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7B - Thunderbird Lake Update 2009 Annual Operations Report Thunderbird Lake Project at Admiral Arleigh Burke Park Prepared for: Kirk W. Kincannon, Director of Parks and Recreation City of Boulder Prepared by: Matt Claussen, Urban Resources Manager Parks and Recreation Department City of Boulder March 10, 2010 01F BID& AGENDA ITEM # P PAGE Introduction The purpose of this report is to provide a year-end assessment for 2009 covering management activities involving Thunderbird Lake, located at Admiral Arleigh Burke Park. This report will review implementation of the Adaptive Management Plan as well as evaluation of the goals described within the management plan. The general components listed below will be described in terms of how they were implemented. At the end of each section, a brief analysis will be presented with a summary at the end of the report. As part of supplemental information, attachments will be used throughout this document as references to some of the activities that took place. Areas of reporting will cover: • Development of Adaptive • Groundwater Monitoring Management Plan • Water Quality • Wetland Mitigation • Project Labor • Water Budget • Project Costs • Water Discharge/Outlet Flow • Water Levels Project Background In 2007, some members of the community contacted the PRAB and City Council requesting that the city increase the water level of the lake and improve aesthetic quality. Department staff held two neighborhood meetings to discuss the changes in the lake and to gather community input on potential management options. Subsequently, staff hired Biohabitats, Inc. to prepare a report that would address the history of the lake, current conditions and to offer four potential management options, These management options were presented to PRAB on September 22, 2008 and the board voted 5-2 to approve Option B, Adaptive Management - No Supplemental Water. The WRAB considered this item at its Jan. 12, 2009 meeting and recommended Option D - Use of Potable Water with multiple fills per year. The recommendations from the PRAB and WRAB were provided to the City Council at the February 19, 2009 public hearing. At this meeting, the Parks and Recreation Department received direction from City Council to pursue Option D (Use of Potable Water - multiple fills per year) for future management actions at Thunderbird Lake. The emphasis would be to periodically use potable water to fill the lake and increase lake surface area. The target size of the lake and its target surface elevation were not determined nor were details of how the lake would be filled. Since then, staff has been working on the next steps for implementing this option. Members of the project team include staff from the Department's of: Parks and Recreation, Community Planning and -Sustainability, Public Works/Water Quality, and Open Space and Mountain Parks Departments in addition to the consulting firm, Biohabitats, Inc. Biohabitats, Inc. developed the management options that were presented to City Council and have developed a lake management AGENDA ITEm pAGE and implementation plan, wetland permit and mitigation plan and groundwater well monitoring protocols. Community members have been and continue to be updated on the work of the consultants and management actions taken at the lake (City of Boulder website location: Parks and Recreation>Parks>Park Updates>Burke Park/Thunderbird Lake). Review of Project Components 1. Development of Adaptive Management Plan Previous reports have documented the assessment of conditions and conceptual model for Thunderbird Lake (Biohabitats, 2008). The management plan summarizes the goals, objectives, and action items along with monitoring and adaptive adjustments that complete a feedback loop to the goals, objectives, and action items. The management plan is intended to be used in conjunction with other guidance pertaining to the City of Boulder Parks and Recreation Department including the priorities and vision set forth in the Parks' Master Plan (2006), annual work plans, funding priorities, and internal Parks maintenance standards. Throughout the discussions of Thunderbird Lake, there have been various opinions and concerns about how best to move forward with management actions to help resolve the issues surrounding the lake. In developing the management plan, it became evident that a vision statement would help build the founding components of a management plan. The overarching vision for the lake is as follows: Parks and Recreation Department maintains the recreational resource of Thunderbird Lake while protecting the natural resources of the property. Thunderbird Lake management helps retain the community passion for the parkas well as promoting education and cooperation with residents. Implementation of management actions responds to changing conditions during the 3 -year period from 2009 - 2011, documents level of efforts, and prepares information necessary for the City Council to re-evaluate the recommended management approach. City Council provided two general goals; a) increase the surface area of the lake, and b) to improve the overall water quality. Staff decided to expand these goals to include ecological factors and opportunities that may present themselves as part of this project. Four primary goals were further defined: 1. Increase the lake surface area to approximately 2.2 acres (water elevation of 5,315 ft); 2. Improve the water quality of Thunderbird Lake; 3. Minimize the changes in wetland function and aquatic habitat; and, 4. Provide opportunities for education and passive recreation. The management plan describes the actions that would help to meet these goals and was written to purposely be flexible. This allows for staff to experiment with activities as new information becomes available or to modify, due to environmental conditions. AGkhllaA ITEM PAGE Some of these management actions included; • Water delivery to the lake via a retrofitted irrigation system, in addition to hydrant delivery as needed; • Wetland mitigation to replace wetland functions that were expected to be lost from inundation of existing wetlands; • Ongoing maintenance practices including treatment for mosquito's and aquatic vegetation; • Weed control around the lake periphery; • Monitoring of lake levels; • Protocols/policy dictating the addition of or discharge of water; • Monthly water quality sampling protocol; and, • Collection of groundwater data. Please see Attachment A for the Adaptive Management Plan. H. Wetland Mitigation The initial steps for implementing Option D required the submittal of a wetland permit (per city code) to review and address any impacts of this option. Part of the mitigation plan was based on a target water level of 5,315 feet in order to reduce the overall impact to existing wetlands (target elevation further described in Section V). The project team submitted the application on April 20, 2009. The following issues were addressed as part of the preparation of the wetland permit application: • Appropriate elevation of water level to accommodate desired outcome; • Amount of wetland mitigation required based on water elevation and site constraints; • Evaluation of the options of water delivery via a hydrant or irrigation system retrofit; and • Evaluation of other project goals as a result of adding water to the lake. Staff developed an approximate timeline for the multiple components of this project including when water may be available and ready to add to Thunderbird Lake. The wetland permit was approved on May 22nd with certain conditions to be met for wetland mitigation success. After a bid process, a contractor was selected and grading construction began on June 24th. AGENDA ITEM #_~Jj PAGI~ rG nit' . 4.0 ~y 111 - -A!" L l L Wetland construction process on west side of lake. During the construction process, staff designed and re-built a section of the existing irrigation system to add a separate water meter to track specific water usage into the lake. - J•.Sti Irrigation retrofit and dechlorination unit installation. A dechlorination unit and underground piping were also added to facilitate the water addition so that issues of supplying water to the new wetland, reducing potential lake sediment disturbance and controlling erosion were addressed. The planting of wetland vegetation for the mitigated area was completed the week of July 13th. AGENDA ITEM PAGE Completed wetland grading and planting. R.r Pik swim, ' i~• l• ._'ML~lw1t'. s.~Xl _ tel.' * Y ~ Adding water into new wetland area via rock sump to control erosion. Water flows were started once the planting was finished to aid in the establishment of the newly planted vegetation as well as to test the new system to ensure dechlorination standards were being met. A supplemental addition of water was added via a hydrant for two days in late July to accommodate the warmer weather and higher evaporation rates. ' July 21, 2009 after a few days of adding water. (%GFNDA ITEM 0 U'f~~~ r PA,faft See Attachment B for wetland permit details. Analysis The initial water flows were irregular due to complications of the dechlorination process and ensuring that inflow to the lake was meeting city and state policy standards regarding release of potable water into natural systems. During this process of normalization and calibration, as well as balancing maintenance needs at other parks, the water levels did not rise as quickly as expected. As a result, some of the wetland mitigation plantings and transplants did not become as established as staff had hoped. In spring of 2010, staff will replant some of this material during a volunteer Earth Day project and coordinate the water additions to supplement water requirements of these plantings. If weather impedes irrigation system startup, the use of a hydrant may be required at this time. It was noted, that when water levels did rise and inundate the mitigation site that surviving plants did respond, and waterfowl used the area quite frequently and aided in bird observations to the park visitors. III. Water Budget Staff worked with city utilities to determine the budgeting for water allocations into Thunderbird Lake. See Attachment C. Using estimated surface area and annual irrigation application rate of 15 gallons per square foot, an annual supplemental water budget of 1,307,000 gallons was established for each pilot project year (2009 - 2011). Seasonal usage terms were applied so that an established amount was designated between March 1 and June 30; and between July 1 and November 30. No supplemental water is to be used during the winter months of December, January or February. Monitoring and tracking of the water usage was performed by the newly installed water meter as part of the retrofitted irrigation system that fed the lake. On left, the dechlorination unit; on right, the new water meter. Any water use that exceeded the allocated water budget, the Parks and Recreation Department would be charged according to the established 2009 Block Rate Structure. ;kGENnA ITEM # VI~ , PAGE-Z- Analysis Late spring and early summer precipitation contributed to beginning lake water levels being higher than expected. Approximate water usage in the Plan was estimated to be approximately 2.8 million gallons. While water flow into the lake did not begin until July 15 due to the wetland mitigation, total potable water usage amounted to 1, 954,380 gallons for the year, in part also due to the higher spring and early summer water level. This did exceed the established water budget by 647,380 gallons and a fee of $12,043.35 were charged to the Parks and Recreation Department IV. Water Discharge/Outlet Flow One of the objectives to meet the goal of increased water quality was to establish a flow-through system to decrease the amount of nutrient buildup within the lake. Simply stated, the amount of water entering the lake would roughly equal the amount of water leaving the lake. The outlet is a pipe that was reconstructed in 2008 that lowered the pipe elevation to better meet the ability to release water (due to the lower water levels). With this effort, the ability to manipulate water levels was improved, Since the primary source of water to the lake currently emanates from the city potable water system, certain regulations dictate how potable water is released into the storm sewer system. The city's existing General Permit from the Colorado Department of Public Health and Environment is not applicable for fill or release of water into or from Thunderbird Lake. In September 2009 a revised state policy was adopted (State of Colorado Low Risk Discharge Policy) defining such water bodies (like that of Thunderbird Lake) will not require permits as a result of adding water to, or discharging water from, such water bodies while adhering to best management practices. w; - 4 J ! 1l ~ y4.- 1 Outlet pipe area on east side of lake. To ensure that best management practices and dechlorination procedures were to be met for water additions and discharges, an internal MOU was developed between the Parks and Recreation and Public Works departments (see Attachment D). This MOU articulates the city and state ordinances that govern incoming water and water discharge from the lake. AGENDA ITEM O , PAGE Analysis bVhile the water levels were increased during the summer and fall months, it was determined that before any release of water would occur, the MOU would need to be completed. The MOUwas signed in late October and park irrigation systems were shut off during that month. In order to maintain the highest water level going into the winter season, no water was released from the lake in 2009. The amount of water exiting the lake in the future will need to be monitored so as not to exceed the capacity of the storm sewer system in heavy rain or similar events. Careful timing and monitoring will be conducted by staff to gauge any potential impacts to water conveyance routes in this area. Dater will not be released until at or near the target water elevation. Appropriate flow rates will be monitored and established by staff'using flow monitoring devices at the outlet pipe. V. Water Levels As indicated in the management plan, water levels were not specifically identified in the City Council directives when the project to add water was approved. Surface water area was evaluated in terms of relative impact to on-site wetlands. Water levels too high would result in greater costs for mitigation and the need to find additional acreage to meet mitigation criteria. Water levels too low would not satisfy community desire and council direction. In coordination with the city Wetlands Coordinator, a target water level of 5,315 feet was determined to meet the goals of city council and have the least detrimental affect to existing wetlands. A wetland mitigation plan was developed based on this target elevation. Staff evaluated the water delivery methods and concluded that changes to the irrigation system to deliver water would require substantially less staff time than monitoring water delivery by hydrant. Initial water additions via the irrigation and dechlorination system began on July 15"'. A water level monitoring stick was read regularly to determine the actual water level progression. 2.10 s, 1.90 ` 1'80., ..f 1.16 i.60 1.5D Aa 'P' 4J Lake water level on June 30, 2009. AGENDA ITEM # v ~ [ PAGE __J_ Analysis Water levels on April 9, 2009 were at an elevation of 5, 312.93 feet. The rain event from April 17 and 18 increased the water level by nearly one foot to 5,313.91 feet on April 22. The ground saturation increased the flow rates in the tile drain to a maximum flow rate of 18.75 gallons per minute. These rates began to slow down as by May 6`h, flow rates decreased to 12.24 gallons per minute and was reduced significantly shortly thereafter. This rain from April and cooler temperatures assisted in keeping the lake levels higher than what was expected. The end result keeping the overall water usage below the estimates given in the management plan; however, the later start of regular water additions also contributed to the lower overall water usage. Flow rates from the retrofitted irrigation system start-up were conducive to maintain appropriate water levels in the lake. This rate fluctuated around 60 gallons per minute in optimum dechlorination conditions. However, during the course bf the dechlorination procedure, staff encountered repetitive issues with poor performance in dechlorination tablet dispersal and eventually required the installation and calibration of new equipment in early fall. This led to irregular water flow and water levels not being as high as expected and not reaching the target water level until October 7rh Any additional water outside the spring rain event came from the city potable water system. Staff coordinated with Public Works for two days to add water via a hydrant to accelerate the water levels. Should future weather conditions result in a drought event and/or if water restrictions are implemented, staff would evaluate the impacts and would review water restrictions as they relate to sustainability and water needs for the city as a whole. VI. Groundwater Monitoring Nine monitoring wells were installed in the vicinity of Thunderbird Lake in spring 2008 with temporary well permits from the State Engineers Office. In April 2009, Biohabitats prepared and submitted applications for permanent well permits which needed to be completed within one year of installation. These permits were awarded in May 2009. As described in the management plan, the purpose of the groundwater elevation data is to help better understand the relationship between lake levels and the surrounding water table. Since the drought conditions in 2003/04, the water table has not rebounded and is likely not to fully recover under existing precipitation conditions. A summary report by Biohabitats, of the ground watering monitoring is provided in Attachment E. .4GEN®A ITEM V PAGE-lb- Analysis Groundwater elevations have continued to be below the historic water table, thus having little positive effect on water levels. It was noted that on April 19, 2009 there was a spike in groundwater levels, most likely resulting from the large rain event that dropped nearly 4" of precipitation in two days. This did generate flow via the the drain, although this flow was short- lived. Groundwater data will continue to be monitored by Biohabitats and information provided upon request of staff. VII. Water Quality Water quality data collected in 2007/2008 indicated the lake has excessive nutrient levels. One of the goals outlined in the management plan is to improve the water quality, which would have benefits iri reducing algae blooms as well as help increase dissolved oxygen levels that may possibly return the lakes' biodiversity of aquatic species. A water quality monitoring plan was assembled with city water quality staff and monthly measurements by city staff began in April and were conducted through October. . -1 • 'if Aquatic vegetative growth on June 9, 2009. Staff also worked with Ottertail Environmental, Inc. to assist with associated issues of algae blooms, vegetation removal and mosquito control. Ottertail staff came bi-weekly beginning in May to check on algae conditions and to add microbes to reduce potential heavy algal growth. Photo logs of the lake were taken to visually assess the vegetative conditions during the summer. Ottertail also monitored mosquito populations (non-vector nuisance species) throughout the season. See Attachment F for the report and graphs indicating sampling data results. ,NGEN®A ITEM #-V , PAGE c. e;AL w;.X =FqW ff View of Thunderbird Lake on August 26; 2009 from shelter (south view corridor looking northeast). Analysis mater quality indicators show that there was minimal improvement overall fbr Thunderbird Lake. The majority of dissolved oxygen levels were below the warm water criteria during June through September. On July 7, very low dissolved oxygen was observed throughout the vertical water column, these low oxygen concentrations were caused by the attempt to remove floating vegetation, The nets had dislodged rooted aquatic plants thus disturbing the sediments and bringing low dissolved oxygen water to the surface. A sulfide smell was present during this maintenance operation. Reduced dissolved manganese was also high in the surface water during this sample event. There was concern that additional algae removal may actually turn the lake into a eutrophic state, have serious odor issues from plant decomposition and using all available dissolved oxygen in the process. Staff decided against the use of an algaecide to control the aquatic vegetation to help counteract the effects of disturbing the sediment, reducing oxygen levels and releasing odors. No further action was taken and stafffocused on water additions to possibly help dilute nutrient levels. Discussions led to the decision to fallow expert recommendations and install an aeration system. This would have a long-term beneficial effect for the lake than relying on the use of chemicals in such situations and replace the non functioning Solar Bee. Vegetation was too dense for the Solar Bee to effectively circulate enough volume of water. VIII. Project Labor 2009 was a difficult year for the department in terms of staffing. The city economy had a strong affect on the hiring ability for both standard and seasonal staff that is normally needed for park operations. In the beginning of the season, the extra effort to get the systems running at Thunderbird, took away from other duties needed at other park sites. AGENDA ITEM # C.tI ~ r PAGE ~ 7i S Y ~l 0 t Nay : S yJ" .~41 ~~1= Park staff working on irrigation retrofit and water supply lines. Most staffing efforts were concentrated in the preparation and installation of the retrofitted irrigation and meter installation and the process for installing and quality checking the dechlorination system. Nearly all the work was performed in-house with the exception of specialty work such as electrical or wetland construction/mitigation. The outsourcing of these areas resulted in the majority of associated labor costs. Outside construction related efforts, staff also performed weed management (IPM) surrounding the lake and in view corridors. Fifty-two hours were spent on IPM associated activities. Thunderbird Lake is normally a lower priority park in terms of IPM issues and staff focused their time on managing species that would have the most impact, both aesthetically and for overall vegetative health (Canada thistle, Russian Olives, Tamarisk). A separate wetland permit was approved in 2007 for removing vegetation in designated view corridors and this work was completed as necessary. Other community desire for vegetation removal outside the view corridors was requested, but fell outside the scope of the permit and could not be completed. This permit expires in 2010 and staff can then evaluate the need for a new permit process that may help address the public comments staff received about visual access and reducing additional vegetation. Ottertail, Inc. has previously spent time removing excess duckweed and algae from Thunderbird Lake. During 2009, Ottertail made ten trips to the lake for microbe applications to help reduce algae issues. In addition, Ottertail staff spent one day (nineteen staff hours) attempting to remove algae before assessing further removal may have detrimental impacts to oxygen levels and increasing odor issues. AGENDA ITEM # V11- , dAGG a~ ~J Algae removal by Ottertail Environmental. Analysis Staff labor was limited to this project as other park priorities and maintenance needs were required in other developed parks. Maintenance and repair of other park irrigation lines, mowing, trash removal were all priorities with reduced staff and pulled away from anticipated efforts towards Thunderbird Lake. In an attempt to meet community demands for other parks and designing a new water delivery and dechlorination system at Thunderbird Lake, managers had to decide on a park-by-park basis how to utilize staff most effectively in park management operations. It was noted in discussions with Ottertail ecologists, that improved water quality via added water, discharge%utflow and the addition of an aeration system, would likely improve the vegetative and water qualityfor the lake. Since water additions can start earlier in 2010, as well as the installation of an aerator and the established MOUfor discharge is in place, there should bean overall positive effect. This combination may result in less staff labor costs to manage vegetation and water level management. Ottertail staff will continue to add microbes and monitor the lake. IV. Project Costs For 2009, project costs have been totaled for all expenditures. The majority of costs resulted from the preparatory work necessary to begin the addition of water. This included; • Permit acquisition for wetland and groundwater wells. • Working with consultants on the development of the management plan; • Irrigation retrofit and metering; • Wetland mitigation and replanting; and, • Equipment and installation to dechlorinate the potable water source. Cost total for the 2009 portion of the Thunderbird Lake project amounted to $93,022. See Attachment G for details. PAGE AGENDA ITEM # VI~ p -u-- 2009 Cost Breakdown Breakdown of costs by category are; • Permitting for wetland and wells $ 3,215 • Consultants Biohabitats, Inc $20,578 • Materials for irrigation retrofit/dechlorination $15,601 • Wetland mitigation $20,132 • Water charges $12,043 • Staff labor towards project (approx.) $14,017 • Ottertail Environmental water treatments $ 4,321 • Water quality monitoring $ 3,115 2010 Projected Costs Overall 2010/2011 costs will be less due to the infrastructure completion done in 2009. Water charges will likely be higher as water additions will begin in concert with the irrigation system startup for parks, thus a full season of water addition (weather permitting). Where possible, staff will continue to evaluate alternatives to reduce costs or gain efficiencies throughout this project. For 2010, estimated projects costs will be approximately $61,421. Some of these costs will be associated with; • $32,386 for estimated water usage; • $7,000 estimated for staff maintenance of view corridors, weed management, etc. • $5,648 for replacement of the Solar Bee with aeration system for oxygenation; • $5,340 for monthly water quality monitoring; • $4,600 for Ottertail Environmental (microbes, mosquito control) • $3,000 for dechlorination materials; • $2,500 for education and outreach materials; • $702 for outlet flow meter; and, • $245 for dechlorination component replacement. Plant Investment Fee In March 2009, a Plant Investment Fee (PIF) ordinance was adopted related to water, wastewater and storm water PIF changes. These changes are to be phased in over the next three years. In brief, these fees are charged when an increase in demand is placed on the city's existing water system. If the use of the retrofitted irrigation system is continued after the completion of this project term in 2011, a PIF fee of $215,186 ($2.47/square foot, for two surface acres) will be charged to the Parks and Recreation department. Evaluation of Goals As part of the Adaptive Management Plan, goals were derived in order to evaluate the performance of management actions at Thunderbird Lake. These goals apply not only to the direction received from city council, but also to the overall enhancement and positive benefit to the lakes' aesthetic and ecological condition. AGENDA ITEM *__Vjj~& PAGE f J Goal 1: Increase the lake surface area to approximately 2.2 acres (water elevation of'5,315 ft.). Goal was met. However, it was much later in the season than staff would have liked. Complications of water delivery dechlorination and staff resources contributed to not meeting this goal earlier and not being sustained during the season. Goal 2: Improve the water quality of Thunderbird Lake. Goal not met. While the algae blooms of past did not develop significant issues this year, algae growth was higher than preferred. The delayed water additions and lack of outlet flow did not significantly reduce the nutrient levels that have contributed to unhealthy vegetative growth. Odor issues seemed to be less, but were still present at various times during the year. Goal'): Minimize the changes in wetland function and aquatic habitat. Goal partially met. The designed wetland construction to facilitate continued ecological function did maintain the functional emergent wetland components for the lake. While new plantings did not take as successfully as preferred, the regular presence of waterfowl during high water times indicated some preference and function for these areas. As ecological function cannot be determined in a single year, the basis for longer term wetland functions are present and will be continued to be enhanced over the next several years. Goal 4: Provide opportunities for education and passive recreation. Goal is in progress. With the project occurring during the course of the summer and fall, staff received numerous comments in regards to the project. New information and details not likely understood before the project were relayed to the community while staff was present on-site. While not a project priority for 2009, an educational working group has been initiated between several agencies, Horizons School and members of the community for interpretive and school based curriculum opportunities as a result of the project. Summary 2009 was a developing year for infrastructure, the management plan, wetland mitigation and staffing support. Since most of these areas are being solidified, the 2010 season should reflect positively upon Thunderbird Lake. Staff's expectation is to be able raise and sustain the water elevation, dramatically increase the water quality using the new aeration system and be able to release water through the outlet in order to better balance out the nutrient-rich water. Once these areas are quality checked and in good form, staff can then focus on education and outreach efforts, improve overall lake aesthetics and caring for the general lake area that will best compliment Admiral Arleigh Burke Park. -,GFM)A ITEM PAGE_~ ATTACHMENT A Thunderbird Lake Adaptive Management Plan June 2009 - June 2011 Prepared Far: City of Boulder Parks & Recreation Department 3198 Blroadway Boulder, CO 80304 303.413.7200 Prepared By: Biohabitats, Inc. 1732 Waxee Street, Suite 209 Denver, CO 80202 303.477.0660 www.biohabitats.com Agaim Biohabitats hrrnr,..rrrrlrA AGENDA ITEM # ___U.,a_, PAGE TABLE OF CONTENTS EXECUTIVE SUMMARY 3 1.0 INTRODUCTION 4 1.1 SIT. DESCRIPTION & PROJIsCT BACKGROUND .............................................................................................4 1.2 ENVIRONMENTAL SETTING b 1.3 MANAGEMENT CONSIDERATIONS 7 2.0 ADAPTIVE MANAGEMENT PLAN 9 2.1 PURPOSE OF THE PLAN .9 2.2 GOALS & OBJECTIVES ..................................................................................................................................9 3.0 IMPLEMENTATION ....................................................................................................11 3.1 LAKE WATER LEVEL MANAGEMENT .........................................................................................................1 1 3.2 WATER QUALITY IMPROVEMENTS .............................................................................................................13 33 WETLAND MITIGATION 13 3.4 ONGOING MAINTENANCE ACTIVITIES ........................................................................................................17 4.0 MONITORING AND EVALUATION .........................................................................18 4.1 OVERVIEW OF MONITORING PLAN 18 4.2 MONITORING PROCEDURES & RECORDKEEPING ........................................................................................18 5.0 SUMMARY 25 LIST OF ATTACHMENTS List of Project Contacts Water Quality Monitoring Procedure Activity Log Interdepartmental MOU for Water Discharge (.pdf) AGENDA ITEM # , PAGE I' EXECUTIVE SUMMARY Boulder City Parks and Recreation Department is conducting a 3-year program to add potable water to Thunderbird Lake as needed to increase the lake size and improve water quality. Because of the number of uncertainties associated with the project, this Adaptive Management Plan has been prepared to outline the goals, management actions, monitoring, and response actions that will occur through June 2012. The primary goals of the proposed activities are as follows: 1. Increase the lake surface area to approximately 2.2 acres (water elevation of 5,315 ft); 2. Improve the water quality of Thunderbird Lake; 3. Minimize the changes in wetland function and aquatic habitat; and, 4. Provide opportunities for education and passive recreation. The management actions described in this plan include: water delivery to the lake through the upgraded irrigation system; wetland mitigation to replace wetland functions that are expected to be lost from inundation of existing wetland shrubs; ongoing maintenance practices including treatment for mosquitoes and aquatic vegetation; and weed control. Monitoring activities will include: lake level measurements (both manual and automatic); monthly water quality sampling; annual observation of the wetland mitigation area; groundwater data collection; and tracking public feedback. In addition, since the Department is committed to being cost effective and efficient, the project will track budget and staffing to assess long-term implications on City resources. This plan is intended to be flexible to allow for staff to experiment with the activities as new information becomes available. Minor shifts in irrigation inflow or outflow drainage will occur throughout the project depending on precipitation, evapotranspiration, and water quality indicators. Ongoing communication of project progress will be provided through monthly community updates and periodic updates to the Parks and Recreation Advisory Board. After June 2012, the results of the project will be summarized and presented to City Council for their consideration about the continuation of the project. AGENDA ITEM # V11. . PAGE I ©Biohabitats, Inc. •RESTORINC THF. EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 2e, 2009 1.0 INTRODUCTION The primary purpose of this Adaptive Management Plan (Plan) is to establish goals, objectives, and actions to address Thunderbird Lake field management including: water management, monitoring for water quality and water levels, vegetation management, and wetland mitigation from June 2009-June 2012. Specifically, the document is intended to establish a framework to capture the dynamic nature of water and wetland monitoring and management at Thunderbird Lake. This section presents background information on the site and the environmental conditions that provide the basis of the decision-making framework. Additional background and assessment information for this project is provided in Potential Future Management Options for Thunderbird Lake, (Biohabitats, February 2008) and a follow-up technical memorandum, dated September 17, 2008, by Biohabitats, Inc. 1.1 Site Description & Project Background Admiral Arleigh Burke Park is located at 490 Mohawk Drive, near the intersection with Pawnee Drive (Figures 1 and 2). The park consists of 6.1 acres and includes Thunderbird Lake, wetland vegetation areas around the periphery of the lake, a concrete walkway around the lake/wetland complex, a gazebo and memorial, trees and irrigated and mowed bluegrass turf. Thunderbird Lake is estimated to have a maximum depth of approximately 5.5 ft when full, have a capacity of 12.5 acre feet (ac-ft) reported in the water right, and historically covered an area of approximately 2-acres'. Based on the city's wetland mapping effort in 2004, the lake (open water portion of the wetland) and adjacent vegetative wetland areas comprised about 2.2 acres which corresponds to a lake surface elevation of approximately 5315.0 ft. The lake has diminished in size over the past several years due to reduced water inflows and severe drought conditions. Currently, the lake elevation varies, and several months during 2008 and early 2009 indicated an elevation of less than 5,313 ft. and a surface area of approximately 1.4 acres. Asa result of lower lake levels, the wetland types have shifted with wetland and riparian woody vegetation becoming established in areas which were formerly covered by water between the current lake's edge and the maintained park landscape. Some community members have recently communicated concern regarding lake levels, odors, and excessive vegetation on the surface of the lake. Over the past several years, the Parks Department has managed the lake by cleaning and inspecting the tile drain that supplies groundwater to the lake, removing vegetation to provide views, installing a solar-powered circulation unit, contracting with local biologists to treat the lake with microbes to improve water quality and to apply larvicide to control Culex species mosquitoes, removal of aquatic vegetation, and researching future management options focusing primarily on water flows and water levels. A study conducted by Biohabitats, Inc. and the Parks Department in 2008 presented various options for lake management including increasing water 1 City calculations based on GIS mapping from aerial photographs showing low and high lake water levels (1984- 2006) indicate the lake's surface area ranges from approximately 1.4-2.6 acres. 013iohabitats, Inc. •RESTORING,niE EARTH AND INSPIRING ECoi.oGJCAI, STEWARDSHIP • March 26, 2009 AGENDA ITEM 9 VII -A . PACE 7-0 Figure 1 Vicinity Map Thunderbird Lake at Admiral Burke Park City of Boulder, Colorado n,uwa C_Nq Or rr7 ~Z 1.''~ Ot i r/ l 4 l . Cay of a8twer J 4y jy~y 111 ~ , a,:,:? ~ v C•t J'? ~+t~~il I'f y7 f(i` .:5 ~iono~4ku•i~e, ` t PvM S.~atian I ; w i -77 K~ Tr,und? ~_eke n Area ~ ' _ ti v ~ rte;r area wa+ - } Park, ~~s ` t... r r- y t,~ 7awrrea OINe q` tl 4 4. v -A N Prepared October 24, 2007 Feet Basemap Source: + p t,ppp wE USGS 7.5 mi W. Topographic Map S! Louisville CO 7994 Nsd Figure 2 Site Plan Thunderbird Lake at Arleigh Burke Park v _ Legend :tl01 .+M4 w ..^r ll~r R1Pm Ca:a1 ~A ~ 1 14 -411 r dr,r~~ .7 <n l lilt Base map: N12005 aerial photograph 0 50 100 150 20QeeI GIS infor,ral from city of Boulder data files ® Prepared by &ohabitats. Inc 5 April 15. 2009 C iohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 AGENDA ITEM # 1111-/3 parr flows to the lake from various sources. The alternatives included no added water options (no action and adaptive management) and added water alternatives (groundwater from a well or retrofitted tile drain, stormwater, ditch water, or potable water). On February 17, 2009, the Parks and Recreation Department presented the various options for managing Thunderbird Lake to the Boulder City Council. On that date, City Council's direction was to proceed with a three-year trial during which the lake would be filled periodically with City tap (potable) water to increase the lake's surface area. The target size of the lake and its target surface elevation were not determined by City Council nor were the details of the manner in which the lake would be filled specified. This management plan will cover a three-year period as directed by City Council. 1.2 Environmental Setting Thunderbird Lake is located in the lowland portion of the city, in an area that is relatively flat and has had a characteristically high water table. The lake was originally constructed in 1918 when the surrounding area was farmland. The lake was originally fed by Frasier Farm Ditch that was replaced by a tile drain in 1952. Frasier family members reported that the tile drain was used to help drain the groundwater from the surrounding property and allow development of the residential community. The 1953 water right for the Frasier Tile Drain states that water is diverted from "seepage and springs" near the center of the NE quarter of Section 5, Township IS, Range 70W2. The State Engineer Office reports that the tile drain line extends 0.51 miles (2,688 ft) to Thunderbird Lake. Other than the reference in the water right to 1.2 cubic feet per second (cfs), there are no historical flow records for the inflow to the lake. Recent observations indicate the inflow to the lake varies (see Figure 3). There are also no records pertaining to the outflow from the lake. There is currently no outflow from the lake. Figure 3 Gallons per Day - flowfram Inlet Pipe 30900 00 2590000 20,000 00 15,00000 - - 10,000.00 - - 5,00000 A At" 0 00 n °°y ~d3~cP@\e,ti~ 2cP \tio°~tic4~, e~e~cP ~e{y°°,~°a, 014 oO d~' gyp' 'k''Sti ,51` a anti 5,', 2 No seeps or springs were observed in this area as part of the previous studies of management options. CBiohabitats, Inc. eRESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • r March 26, 2009 r]Af?C 7-~2- The property is underlain by calcareous clayey colluvium, and the lake is located on a Pierre Shale bedrock outcrop. Outflow from the lake (when flowing) goes into a drain on the east side of the lake that flows to the storm sewer (corner of Pawnee and Thunderbird Drive). A second gated outlet for irrigation on the north side of the lake has not been used for a long time (and reportedly has no connection to the city sewer system). 1.3 Management Considerations A water budget for the lake was conducted as part of the evaluation of water management options, and information on the water budget is provided in Biohabitats' past reports (February and September 2008). The purpose of the water budget is to estimate inputs and outputs and change in lake storage over time. Briefly, inflow factors include precipitation (falling directly on the lake and runoff) and the drain inflows, and output factors are evapotranspiration (ET, combination of lake evaporation and transpiration by wetland plants) and discharge through the outlet on the east side of the lake. For the purposes of this study, it was assumed that direct groundwater discharge into the lake is roughly equal to loss to groundwater leakage. The results of the water budget were used to estimate the water needed to maintain the lake level at a stable elevation under average climate conditions as discussed later in this plan. The wetland zones which have developed at Thunderbird Lake include emergent wetland, shrub- scrub wetland, and open water. The emergent and shrub-scrub wetland occurs in two zones which are determined by the lake elevation (Figure 4). Upland vegetation occurs generally above elevation 5316.0 feet. Emergent wetland is dominated by well-developed native emergent wetland species, mainly bulrush with smaller areas of cattails (occurring at less than 5314 ft). This is the larger of the two wetland vegetation zones and includes a large bulrush patch on the west side of the lake where the bank slope is more gradual. Shrub-scrub wetland is comprised of native vegetation such as sandbar willow and plains cottonwood (extending from 5,314 to 5,316 ft). Some of the woody vegetation in this zone was thinned in 2008. Upland includes non-wetland vegetation located at current elevations of 5,316 and higher, within 25 feet of the edge and acting as a wetland buffer. Vegetation includes plains cottonwood saplings, alfalfa, and Kentucky bluegrass. Functions performed by these wetland and buffer areas include shoreline protection, wildlife habitat, food chain support, water quality improvements, groundwater discharge and recharge, passive recreation, and education. UBiohabitats, Inc. •RESTORINC THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 GENOA ITEM #..~..1 L o PAGE 7-3 Figure 4 Wetland Vegetation Zones (April 2009) Thunderbird Lake at Admiral A leigh B!1rk? Park ° a v L - al X i ,tent, r r. 15 14 1 15 ~ ° e l s li l' 'i Ler~,+nd , 7-_ Open water. 5312.7 ft-orittern, 1.39 ac 14 e !S I Emergent wetland.5314-53131t.O51 ac. 5 h ru bscrub wetland, mostly 5315-5314 ft 0.43 ac - t' ° ~~.rA, t✓r ° Topo points, elevation as 53" ft Contours (1 ft intervals] 2U]e xwt/nnd ir•?a Base map. 2005 aerial photograph D 50 100 150 200eet W E Topographic information from City of Boulder GIB data files Prepared by Biohabitats, Inc S April 15. 2009 OBlohabitats, Inc. •RESTORING THE EARTIi AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 AGENDA ITEM - V_ -I ~V - n PAGE l 2.0 ADAPTIVE MANAGEMENT PLAN 2.1 Purpose of the Plan This management plan is based on an adaptive approach which generally refers to an ongoing process of: 1) Assessing conditions; 2) Designing a model of the system; 3) Implementing a plan; 4) Monitoring the changes; 5) Evaluating the results, and 6)Adjusting actions. "Adaptive management requires an explicitly experimental - or 'scientific'- approach to managing conservation projects. Specifically, it is the integration of design, management, and monitoring to systematically test assumptions in order to adapt and learn"3 Previous reports have documented the assessment of conditions and conceptual model for Thunderbird Lake (Biohabitats, 2008). This Plan summarizes the goals, objectives, and action items along with monitoring and adaptive adjustments that complete a feedback loop to the goals, objectives, and action items. The Plan is intended to be used in conjunction with other guidance pertaining to the City of Boulder Parks and Recreation Department including the priorities and vision set forth in the Parks' Master Plan (2006), annual work plans, funding priorities, and internal Parks maintenance standards. 2.2 Goals & Objectives The overarching vision for the lake is as follows: Parks and Recreation Department maintains the recreational resource of Thunderbird Lake while protecting the natural resources of the property. Thunderbird Lake management helps retain the community passion for the park as well as promoting education and cooperation with residents. Implementation of management actions responds to changing conditions during the 3 -year period from 2009 - 2012, documents level of efforts, and prepares information necessary.for the City Council to re-evaluate the recommended management approach. Specifically, the primary goals of the proposed activities are as follows: 1. Increase the lake surface area to approximately 2.2 acres (water elevation of 5,315 ft); 2. Improve the water quality of Thunderbird Lake; 3. Minimize the changes in wetland function and aquatic habitat; and, 4. Provide opportunities for education and passive recreation. 3 Salafsky, N., R. Margoluis, and K. H. Redford. 2001. Adaptive Management: A Tool.for Conservation Practitioners. Biodiversity Support Program, Washington, DC. ©Biohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 A(;FNDA ITF-M t# V11 -R . PAGF- 2~5' Objectives and actions for each goal are listed below and described in more detail in the following subsections. Table X Summa of Goals, Objectives, and Actions Goal Objective Actions 1. Increase the lake surface area to a roximately 2.2 acres (water elevation of 5,315 feet). Manage water levels so that • Setup a fill system equipped with a de-chlorination lake size is greater than unit. recent low level by initial • Fill to target elevation of 5315 ft. and refill if needed. and on-going replenishment See Table 2 for estimated refill schedule. with potable water as • Measure water elevations monthly (and/or before and needed. after filling) to determine fill volume. • Track fill volumes for future evaluation. 2. Improve the water quality of Thunderbird Lake. a. Lower trophic status of Reduce accumulated nutrients by opening low outlet lake. (at 5313.7 ft) in Summer 2009, and partially flushing b. Reduce the likelihood of out existing water prior to or during filling to target nuisance algal blooms. elevation of 5315 ft c. Attempt to create Monitor water quality parameters in accordance with dissolved oxygen levels protocol described herein. in the lake that can Consider additional treatment such as an aeration support desired aquatic system or fill scenarios if water quality does not species (beneficial larvae, show improved trend toward meeting evaluation zooplankton, fish, and criteria in Table 5. amphibians). Continue past practices for algae treatment, duck weed removal, and mosquito control. Consider additional control measures if insufficient improvements observed. 3. Minimize the changes in wetland function and aquatic habitat. a. Re-create a shrub-scrub • Create new sbrub-scrub wetland at elevations 5315 wetland similar to ft. to 5316 ft. See wetland mitigation discussion for existing shrub wetlands more detail. that will be impacted by . Plant emergents to enhance their establishment & adding water. function in the 5314 to 5315-ft zone. See wetland b. Re-create emergent mitigation plan for more detail. wetland in the area • Establish ground cover and woody plant (trees and currently occupied by shrubs) cover of wetland species (FACW- or wetter) shrub-scrub wetland and document survival rate and percent cover that would be lost due compared to reference area (i.e., existing on-site to adding water. shrub wetlands) after five years. c. Operate within the • Improve open water habitat by increasing surface wetland permit area and depth and water quality as described in conditions. other objectives. Evaluate use of temporary irrigation as needed to enhance establishment of shrubs. CCBiohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP 0 - _ March 26, 2009 np~ AGENDA ITEM # &-I, PAGE 2 • Monitor groundwater in mitigation area to assess hydrology. 4. Provide opportunities for education and assive recreation. a. Maintain view corridors. • Maintain view corridor and mow corridors as needed. b. Improve visitor • Survey and assess user experience. experience. . Remove terrestrial weeds and lake surface vegetation c. Reduce lake surface as needed, vegetation. • Develop possible interpretive opportunities. d. Maintain park at B level. . Track staff and expenses for reporting. 3.0 IMPLEMENTATION This implementation section covers lake water level management, water quality management, and wetland mitigation activities. Management under special circumstances such as drought conditions. Should the City experience a drought, the addition of tap water will need to be reevaluated in light of other park and City-wide priorities. 3.1 Lake Water Level Management In June 2009, the City modified the park's existing irrigation system to supply water to the lake. This system is metered separately from the regular park irrigation system to accurately account for water budgeted towards this project. During the irrigation season, staff will take weekly meter readings to maintain an accurate status for water usage and allocated financial budget for any overuse of water. Any use of water from hydrants will also be charged toward the water budget for Thunderbird Lake for total water amount used. Water charges will be in line with the approved Water Rate Structure for that calendar year. Coordination with other city staff in regards to water budget and allocations (Public Works) will be conducted. Water supplied to the lake will run through a dechlorination chamber equipped with sodium sulfite tablets, and then be channeled through irrigation piping and two gravel sumps before entering the lake. A metering and flow device will regulate the flow of water. Parks staff reports that this system has a capable flow rate of about 80 - 100 gpm (or more if desired) and can operate continuously. The water delivery will be periodically tested to ensure proper dechlorination under the guidance of city water quality staff. Upon completion of the wetland mitigation, the irrigation system will be turned on to allow filling until the target maximum elevation of 5315.0 feet is achieved. Then, the rate of water inflow will be set to allow for continued minimal outflow and a relatively stable water elevation of 5,315 ft. During the growing season, ongoing additions of city tap water to Thunderbird Lake are expected to be necessary in order to counter the anticipated water loss and to improve the water quality of the lake. A preliminary schedule of water additions to the lake is presented in Table 2. As shown in the table, after the initial fill, less than one acre foot per month is expected to be needed during the OBiohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 growing season to account for the average evapotranspiration rate of the water in the lake, wetland vegetation, and minimal outflow. However, high precipitation in Spring 2009 stimulated more significant growth of emergent vegetation along the edge of the pond. As a result, actual ET may be higher than initially estimated, and as a result, actual fill volumes may need to be higher than estimated. The need for and feasibility of water additions in the winter months will be evaluated during the course of the trial period. Initially, water additions will be limited to during the growing season ending in October 2009 and commencing the following year on or about May 1. Should the lake goals be met in future years because of increased inflows from precipitation and/or groundwater from the tile drain, the ongoing addition of water may be suspended: monitoring of lake levels and water quality parameters would continue. Table 2 Estimate of Thunderbird Lake Fill Volumes for First Year Period Fill Volume Fill Duration (days) Outflow ac- ft gallons Irrigation Line 9D gpm 0.40 ac-ftlda Initial Flush and Fill Fill to 5313.7 0.0 0.0 none Flush 5.0 1,629,260.00 12.6 max Fill to 5315 3.0 977,560.00 7.5 none Monthly Fills Aug-09 0.9 282,370.00 2.2 Sep-09 0.9 279,590.00 2.2 Oct-09 0.7 213,520.00 1.6 Nov-09 0.0 0.0 Dec-09 0.0 0.0 outflow will Jan-10 0.0 0.0 average approximately 1 Feb-10 0.0 0.0 gpm Mar-10 0.0 0.0 Apr-10 1.0 325,860.00 2.5 May-10 0.1 22,660.00 0.2 Jun-10 0.3 91,970.00 0.7 Jul-10 0.8 259,710.00 2.0 11. First year total 7 Second year total 4.5 Assumptions: Water elevation at end of June will be approximately at the lower outlet, 5313.7 ft. Target fill elevation is 5315 ft. Initial flush and fill will occur at the end of June 2009, and Lake will be full at beginning of July. Maximum outlet flow will be determined based on field measurements. Average outflow may be adjusted based on water quality measures and in accordance with Adaptive Management Plan. Total lake volume below 5312.7 is roughly 3 ac-ft. Irrigation line is shut off from November through March. Monthly fills are based on average monthly rainfall. COBiohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March ,.~p. AGENDA ITEM 6'ME 4`0 3.2Water Quality Improvements Water quality data for the lake collected during 2008 indicate that it has excessive nutrient levels (See attached data, J. Shelley, COB Water Quality). Adding water which contains virtually no nutrients and removing nutrient-rich water should, over time, reduce the nutrient concentrations of the water in the lake. This should also reduce the likelihood of nuisance algal blooms and should help maintain dissolved oxygen levels in the lake that can support desired aquatic species (beneficial larvae, zooplankton, fish, and amphibians). Creating water flow-through ability could further improve the overall quality of the water in the lake. City staff will follow recently adopted state policies (Colorado Department of Public Health and Environment, Low Risk Discharge Policy), that covers the fill and discharge of water to and from Thunderbird Lake, respectively. Through this policy, no permits are required for the planned additions or release of water at this site. However, the city staff has developed an interdepartmental Memorandum of Understanding that addresses discharges to the storm water utility system. This MOU was approved by the city manager November 9, 2009 and is attached at the end of this document. Parks staff has reconstructed an outlet pipe (elevation of 5313.7 feet) which has been equipped with a control valve. We propose releasing water at a rate of a minimum of 1 gallon per minute at the onset of the trial program. This rate could increase or decrease depending on factors such as precipitation, groundwater inflows, and temperature. Therefore, the adaptive management plan will include a monitoring program which will be used to evaluate inflow and outflow rates. Further, a monitoring device can be placed at this outlet to accurately measure flow, as well as other data that meets the best management practices as defined in the Low Risk Discharge Policy. Water quality could be further improved by installing an oxygenation unit (aerator) on the bottom of the lake. Oxygenation is needed to maintain dissolved oxygen levels that support fish species. Currently, a Solar-Bee unit floating on the lake surface attempts to mix lake water but does not oxygenate the water. The Solar Bee unit will likely be removed if the aerator is installed. Discussions of water quality monitoring parameters and response actions are provided in Section 4. Thunderbird Lake is already a site where bacteria are added to the lake to help reduce algal bloom occurrences. These additions are thought to be responsible for the large reduction in algal blooms during the past few years and in the increased water clarity (E. Fleming, OtterTail Environmental, Inc., pers. comm.). This routine maintenance practice will continue during the management plan period. Should algal blooms persist, the City may explore potential additional treatments, including herbicides, as allowed under City programs. 3.3 Wetland Mitigation A wetland permit application was submitted on April 20, 2009 to address the upcoming water fill c Biohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26 , OU a and management activities including wetland mitigation at Thunderbird Lake. The City of Boulder Planning and Development Department issued the wetland permit for the current project on May 22, 2009. Although the project will not impact the overall wetland size (because the City includes open water in its wetland definition), wetland functions are expected to be impacted by changes in wetland type around the periphery of the lake due to inundation when the water surface rises to 5315 feet. Adding tap water to achieve that elevation was initially expected to inundate approximately 0.51 acres of emergent wetland and 0.43 acres of shrub-scrub wetland, which are located below 5315.0 feet elevation. (Refer to the wetland permit application for a summary of the impacts.) The mitigation plan is intended to replace some wetland functions that may be lost by the conversion of one wetland type to another. The plan covers mitigating for the loss of 0.43 acres of shrub-scrub wetland by creating shrub-scrub wetland next to the northwestern corner of the lake and improving the quality and diversity in the open water section of designated wetland. Because heavy spring precipitation caused a natural rise in the lake level in June 2009, some of the anticipated impacts from added water did not occur and hence mitigation actions were modified. Although 0.21 acres were initially proposed, park space limitations resulted in 0.14 acres actually being created and/or enhanced with supplemental shrub vegetation. Replacement plantings of bulrush were also reduced, because impacts to emergent wetland plants from added water were less than expected. Figure 5 shows the areas planted in June 2009. (013iohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STF.WARDSIIIP • March 26, 2009 ~j AP_CAI~Ie I IZRA It V H4 PACE "D Figure S Final Mitigation Planting Area r ~ 1iDD wq, tt. sot~i . Al +,263 sq!n t-- I D %3or sq. c yg 1,a73,,y.rt• - - I re a;l raocq, n, , ~ y I el, Thunderbird Lake Project1 Wetland Mitigation Area 1 s June 2009 revmwtc Grnanl P.afda ~IJoI leScnlal Ll !Zr»)hrt~,5717' 6)16 c'o.r 1 Ab.Y',. i, ©Biohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 1m(_I0 -n..e. 7,l Grading Plan Grading operations were completed during the week of June 29, 2009 along the west side of the lake to create a depression or wetland basin with smooth gentle slopes. The removed material was transported to Valmont City Park by truck where fill material is needed for other project development. The mitigation was done in conjunction with retrofitting the existing irrigation system to provide water to the lake. As a result, grading accommodated the final layout design of the revised irrigation system and was overseen by a City construction manager. The existing soil material was found to be too poor quality to salvage, so a small amount of topsoil (approximately 40 cubic yards) was provided by Pioneer Co. landscape suppliers prior to planting. The mitigation area was graded to achieve an elevation of approximately 5315.5 feet. This elevation was determined based on groundwater data collected on the west side of the lake (near the mitigation area). Wells in the area have been measured since June 2008. The data show that in the nearest well to the mitigation area (MW3), the water table was above 5313 for MW3 Groundwater Elevations (ft) most of the previous year, and above 5314 5316 for most of Spring 2009. Increasing the lake 5315.5 - level may not raise the water table evenly 5315 - 5314.5 throughout the mitigation area. Instead, 5314 - some increase in groundwater is expected to 5313.5 - - - - occur from the infiltration of fill water and 5313 - - mounding from the lake with a downward 5312.5 5312 - gradient away from the lake. Therefore, the 5311.5 - wetland shrub-scrub species will be planted 5311 along the expected groundwater gradient, 5310.5 5310 • with more tolerant shrubs with deeper-root 8-Jun-08 16-Sep-08 25-Dec-08 4-Apr-09 13-Jul-09 potential placed on the western edge of the - created area. Vegetation Planting Plan The main objective of the mitigation is to create a shrub-scrub wetland that is comparable to existing shrub-scrub wetlands at the site.4 More specifically, the intent is to establish a ground cover and woody plant (trees and shrubs) cover of wetland plant (FACW- or wetter) of species that is similar (e.g., at least 80%) to the existing shrub reference area after five years. To achieve this goal, a variety of container-grown native wetland plants were installed along the edge of the lake (Table 3). 4 Another proposed goal of the mitigation in the original permit application was to recreate emergent wetland in the area currently occupied by shrub-scrub wetland that would be lost due to the addition of water. However, these impacts occurred naturally from heavy precipitation in Spring 2009, not as the result of water additions. Therefore, an modification letter was submitted, and the City agreed to waive the requirement for mitigation of emergent vegetation. (0I3iohabitats, Inc. *RESTORING THE EARTH AND INSPIRING ECOLOGICAL. STEWARDSHIP • March 26, 2009 AGENDA iTFM # V'11-9 aefl.r. 32, Table 3. Container-grown Stock Used to Create Shrub-Scrub Wetland Quanti Plant Description Common Name Size 38 Salix irrorata Bluestem Willow #1 400 Salix exi ua Coyote Willow 7 ci 8 Salix am daloides Peach-leaf Willow #5 115 Carex rae racilis Clustered Field Sedge 10 cl 115 Carex nebrascensis Nebraska Sedge 10 ci 135 Juncus torre i Torre 's Rush 10 d 135 Eleocharis alustris Creeping S ikerush 10 ci 175 Scir us acutus Hardstem Bulrush 10 ci 175 Scir us validus Softstem Bulrush 10 ci 3 Rosa woodsh Wood's Rose #5 6 Prunus americans American Plum #5 6 Prunus vir iniana Chokecherry #5 10 Ribes aureum Golden Currant #5 10 S m horicar os occidentalis Snowber #5 Following installation of container-grown stock, the wetland mitigation area is to be seeded by hand with a mixture of native wetland plant species, fowl bluegrass (Poa palutris) and prairie cordgrass (,4partina peetinata), at rates of 3 and 1 pounds per acre, respectively. Noxious weeds in the mitigation area will be controlled per city IPM best management practices. The eastern shoreline of the lake is relatively steep and is potentially subject to erosion once additional water is added to the lake. During the project period, City staff will monitor condition of the bank and plant rhizomatous wetland plants, such as American three-square, Baltic rush, and clustered field sedge, as needed (e.g., on one-foot centers) to prevent shoreline erosion. 3.4 Ongoing Maintenance Activities Certain activities that are on-going will continue at Thunderbird Lake in accordance with City practices and draft maintenance standards. These include maintenance activities such as mowing and turf care, irrigation, weed control, tree thinning for safety and clearance, removal of aquatic vegetation (duckweed), trash removal, outlet and inlet maintenance, and mosquito control. General maintenance also includes trying to keep signs, park benches, bridges, trails, perimeter fences and other amenities in a proper state of repair. Thunderbird Lake is a part of the city of Boulder's West Nile Virus Mosquito Management Plan (WNV MMP) which is described in more detail at www.bouldercolorado.gov. The WNV MMP was adopted by City Council in March, 2006. The main objective of the WNV MMP is to reduce the risk of human West Nile Virus infection while minimizing environmental impacts. There are many species of mosquitoes in Boulder, but only three - Culex tarsalis, Culex pipiens and Culex erythrothorax- can transmit or vector West Nile Virus. The city monitors potential mosquito breeding sites citywide for vector mosquito larvae throughout the entire WNV season (-May ©Biohabitats, Inc. •RESTORING I'm EARTH AND INSPIRING ECOLOGICAL. STEWARDSHIP • March AGENDA ITEM ~ / 26, 2 o ~ through September). Areas found to have Culex larvae are treated with Bti (Bacillus thuringiensis israelensis) to control the larvae. The larval monitoring/treatment are followed up with adult mosquito trapping. In cases where adult Culex adult mosquitoes are found and are shown to carry WNV, staff and City Council could decide to conduct targeted spraying for adult mosquito management. To the extent possible, the Parks Department will attempt to implement the 3-year trial project using staff time and funding that is in keeping with efforts at the other parks. Although Thunderbird Lake represents less than 1% by acreage (Parks and Recreation Master Plan, 2006) of the City parks network, it is one of only a handful of lakes managed by the department. Therefore, staff time will be devoted to Thunderbird Lake as needed to implement this adaptive management plan. 4.0 MONITORING AND EVALUATION Monitoring and evaluation are conducted in order to determine if management actions are achieving the desired management goals both in the short term and in the 3-year trial period. 4.1 Overview of Monitoring Plan In the short term, monitoring data will allow staff to assess the effectiveness of specific management actions and to adjust priorities in order to best achieve the project goals. In the long term, the monitoring information will provide the basis of the staff report to City Council. To track resource changes and trends over time, monitoring should be tied to project goals, conducted at designated intervals, and be based upon specific protocols. Table 4 summarizes the monitoring plan and response actions by project goal. Specific procedures are provided below. 4.2 Monitoring Procedures & Recordkeeping 4.2.1 Lake Elevation & Flow through Lake elevations will be measured manually by checking a staff gauge located on the west side of the pond in keeping with the city's monitoring practices started in 2008 as well as the water flow meter installed for this project. In addition, an automatic data logger, located next to the staff gauge in a surface water station (constructed of 2"-PVC pipe), will be downloaded periodically. The information on lake level can be used to approximate the amount of time the lake level is above 5,314 ft (two acre area) as well as the relation of the lake level to water additions. Flow meters will be installed at the potable water inflow and in the outflow pipe. These meters will be read via auto data loggers. The tile drain inflow will be estimated manually at the same time as the weekly lake levels are read. ©13iohabitats, Inc. •RFSTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • AGENDA ITEM # AV Table 4 Summary of Monitoring and Response Actions Timeframe Monitoring Response Actions 1. Increase the lake surface area to approximately 2.2 acres (water elevation of 5,315 feet). Monthly from Manually measure If manual monitoring indicates water September- April, and water elevations elevation is below 5,314 ft for more than I- on a weekly basis 2 weeks, adjust inflow and outflows during May-August. accordingly. If manual monitoring indicates water is at or above 5,315 ft, consider reducing fill rate 2x per year Download automatic Incorporate into annual reviews as data logger records of described below. daily lake levels Annually Prepare annual Adjust monitoring program as needed to summary of lake levels provide appropriate level of information for decision-making in years 2 and 3. 2. Improve the water quality of Thunderbird Lake. Monthly sampling Monitor general water If water quality conditions decline or do not quality parameters listed meet desired water quality parameters as in Table 5 and compare outlined in Table 5, consider an increased results to determine rate of fill and/or increased discharge rate. baseline conditions. If water quality is satisfactory and water levels are above 5,314 ft, consider reducing fill rate. Continue BMPs for algae treatment and mosquitoes, and evaluate installation of aeration system. Consider alternative treatments if insufficient improvement observed. If annual summary indicates that water additions and flow through are not improving water quality to be within the desired parameters, or it is proving too difficult to control the level of water and water quality, consider options such as installation of aerator, bottom dredging, and/or a combination of methods to meet QBiohabitats, Inc. *RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • AGENDA ITEM 4 March 1 the goal. 3. Minimize the changes in wetland function by improving aquatic habitat and mitigating changes in wetland types. Annually - Ix Visit site for visual Consider supplemental plantings to replace during growing reconnaissance and utilize lost species if e.g., density and diversity of season photopoints of the native species (including volunteer species) mitigation site indicates it may be difficult to achieve 80% cover after 5 years). Approximately 3 Visit the site during each Control of noxious weeds per City policies. times per year growing season during the Depending on type of weed and extent of life of the project to locate infestation, weed occurrences would be and control any noxious controlled by mechanical methods such as weeds digging or whipping (the preferred method) or by hand application (wicking or backpack spraying) of a herbicide labeled for use in wetlands. 2xs per year Monitor groundwater to Consider using temporary irrigation as assess if wetland hydrology needed to enhance establishment of shrubs. desires are met near mitigation area. At outset and after 5 Collect vegetation point- Assess likelihood of all or a portion of the years cover data in existing shrub mitigation wetlands surviving given future wetland along 2 transects at water management plans and groundwater the outset of the project. data collected during the project period. If And after 5 years, complete survival appears unlikely, consider approximately 4 transects revegetation using upland species or turf in in the mitigation area to keeping with park goals. compare to existing area. 4. Provide opportunities for education and passive recreation. Annually Track amount of staff time If the time and funding contributed to the spent on project. project by Parks is significantly disproportionate to other parks, than the implementation plan will be reviewed to identify possible efficiencies. Annually Track direct expenses Maintain park site at `B' level maintenance invested of the project standards in addition to this project's goals. Periodically Survey neighborhood Share results with Parks and Recreation opinion about lake Advisory Board. condition and visitor experience. (O iohabitats, Inc. *RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 ,r-ce,InA i'T'r-RA 1111-A ©MIC Information on water inputs and outflows and lake water levels will be used to recalculate the water budget on for a year-end check and to plan for the upcoming growing season. Information from the updated water budget will be used to estimate the new fill schedule for the upcoming year. 4.2.2 Groundwater Elevations Groundwater elevation data will be collected two times per year by downloading automatic data loggers installed in the monitoring well network. Detailed descriptions of the groundwater wells and methods are presented in the Groundwater Monitoring Plan dated February, 2009. The depth to groundwater information can be used to understand the relationship between lake levels and the water table as well as to better understand the relationship between precipitation and tile drain inflow to groundwater levels. 4.2.3 Water Quality Water quality monitoring and data management will be performed by city water quality staff per the April 2009 monitoring plan prepared by Jim Shelly, Water Quality Specialist As outlined in the attached City plan, water samples will be collected from the lake at three locations one deep water location, one mid-dam, and one 25 feet out. The monitoring will be done on a monthly basis from April through October (during ice-free periods). At least one time per year, it is recommended that the monitoring occur before and after an addition of potable water to observe changes in the profile as the result of mixing. At each location, general water quality measurements will be measured in the field and by laboratory analysis. The list of parameters will cover nutrients, microbiological, and general chemical/physical characteristics as shown in Table 5. Field screening will include Secchi disk depth as well as other parameters to allow preparation of a vertical profile (i.e., reservoir profile based on pII, specific conductance/Total dissolved solids, and temperature). Laboratory analyses will include phosphorous (as total, ortho phosphorus, and dissolved) and nitrogen (as ammonia and nitrate) for nutrients; chlorophyll and Secchi disk depth (as well as phytoplankton and E coli) for microbiological measurements; and alkalinity, hardness, turbidity, total suspended solids, sulfate, chloride, and total organic carbon. Additional observations will be made for lake color, extent of vegetation cover (algae and duckweed) and wildlife (e.g., presence or absence of macroinvertebrates and vertebrates species and estimated trends in abundance based on general review and anecdotal findings). The purpose of the data collection will be to obtain baseline information and observe trends during the course of the 3-year trial period. This effort will be a continuation and expansion of previous water quality sampling collected at the lake. As discussed in Biohabitats 2008 report, Thunderbird Lake exhibits hypertrophic conditions that are undesirable to residents because of the prevalence of aquatic vegetation (algae blooms and duck weed). Qualitative measures of percent cover for aquatic vegetation will be estimated based on visual observation and used to track project progress toward meeting the goal of improved water quality. A goal for lake surface coverage of duckweed may be 30-40% of the total surface area at any one time. CoBiohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 AGENDA ITEM # VII -A PA(.r- ~7 The State of Colorado and City of Boulder do not have specific water quality criteria for small lakes. According to Jim Saunders at the CO Department of Public Health and Environment, new lake standards will be proposed to the Colorado Water Quality Control Commission (WQCC) in early 2010 and will likely cover total phosphorous and chlorophyll by region and lake size. However, even if the new standards are adopted, they will not apply until 5 years after passage. The US EPA 304a criteria include recommendations for total phosphorous, chlorophyll, nitrate, and Secchi depth; however, they are considered very low, and as such, are not likely to be used as the basis for the State's recommendation to the WQCC. Available criteria and historical data are shown in Table 5 to provide a starting point for future evaluations. However, in the absence of specific water quality standards, the data evaluation will be primarily qualitative to identify improvements in comparison to previous characteristics. As indicated in the table, > 20 ug/L chlorophyll is a rough threshold for algae blooms, and this level often corresponds to about 1/3 of the total phosphorous (J. Saunders, Personal communication). Thus, maintaining less than 60 ug/L of phosphorous in Thunderbird Lake may be an approximate target for desirable water quality. (Note, an initial target of 40-50 ug/L total phosphorous in the lake was suggested in the Biohabitats 2008 report). It is uncertain how much the accumulated nutrient-laden sediments will continue to contribute to the internal nutrient loading in the lake. Therefore, the extent to which lake water management practices alone can help create good water quality at Thunderbird Lake is difficult to say at this time. If monitoring water quality and the percent cover of aquatic vegetation fails to show a positive trend after one or two years of the potable water additions, then other management practices such as dredging may need to be re-evaluated. During the first year of the program, City staff will investigate the cost and utility of including sediment monitoring in the Plan. In addition, if no significant changes are observed for algae growth due to the addition of potable water in 2009, staff will evaluate the installation of an aeration system to facilitate better water circulation, dissolved oxygen levels and increased overall water quality. C013iohabitats, Inc. *RESTORING THE EARTH AND INSPIRING ECOLOGICAL, STIWARDSHIP • March 26, 2009 22 AGFNnA ITr-M it VII-P) CIA-r- ~J~ Table 5 Water Quality Parameters and Available Criteria Parameter Criteria unit Source Physical and Biological Dissolved Oxygen (DO) >5 mg/L CWQS Segment 5 H 6.5-9 CWQS Segment 5 Fecal coliform 200/100 mis CWQS Segment 5 E. Coli. 126/100 mis CWQS Segment 5 Temperature April-December Chronic 26.5 C CWQS Segment 5 Acute 29.3 C Clarity No limit currently established Clarity typically relates to phytoplankton Secchi disk biomass, good to have phytoplankton for TSS oxygen production, however must manage Turbidity levels to avoid odor producing blooms Phytoplankton counts No limit currently established Minimize odor producing phytoplankton species Chlorophyll a 20 ug/L Rough threshold to minimize algal blooms; Carlson tro hie index Inorganic Total alkalinity >20 me/L, J Shelley based on minimum for fish growth. Total Ammonia <2 mg/L (typical chronic USGS NAWQA Circ. Nutrients in Nations exposure for fish) Waters Chlorine 0.011 mg/L (chronic) CWQS Segment 5 0.019 mg/L (acute) Chloride 250 mg/L Aesthetic drinking water level (CWQ suggested Secondary Drinking Water Regulation) Nitrate <10 mg/L 10 is the Colorado Primary Drinking Water Standard; lake levels should be lower, to reduce the potential for odor producing algae blooms Nitrite <1 mg/L .1 is the Colorado Primary Drinking Water Standard Total Phosphorous <60 ug/L Rough threshold to minimize algal blooms; Carlson tro hic index Dissolved phosphorous No limit currently established Form of phosphorous that algae can utilize, As low as possible reduce the potential for odor producing algal blooms Orthophosphorous No limit currently established Form of phosphorous that algae can utilize, Low as possible (component of reduce the potential for odor producing algal dissolved P above) blooms Sulfate 250 mg/L Aesthetic drinking water level (CWQ suggested Secondary Drinking Water Regulation) Est. Total dissolved solids (TDS} 500 mg/L Aesthetic drinking water level (CWQ suggested Secondary Drinking Water Regulation) Total hardness No limit currently established Specific conductance (see TDS) 820 umhos/cm Estimated aesthetic drinking water level Total organic carbon (TOC) No limit currently established V iohabitats, Inc. •RLSTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 AGENDA ITEM # VI f -g , PAGE-3 4.2.4 Wetland Mitigation Monitoring to assess the success of the Thunderbird Lake wetland mitigation project will include reviewing planting success (survival, density); invasive cover and control; as well as well as anecdotal reports of use by birds and other species from water quality reports, public comments, and staff observation. The primary ecological functions of the wetland vegetation that will be reviewed include shoreline protection, wildlife habitat, and food chain support. Other functions of the fringe wetland area include water quality improvements, groundwater discharge and recharge, and recreation and education which may also be qualitatively noted but are more difficult to assess. Wetland Vegetation The onsite shrub-scrub area will serve as the reference area whose vegetation characteristics will serve as a model for the mitigation area. To see if the project is meeting the objective of providing similar shelter and food supply, the mitigation area will be monitored annually with visual reconnaissance and photo-points. The measures of success will include the survival rate and the percent cover or desirable native shrub species. Weeds City parks staff will visit the site approximately three times during each growing season to locate any noxious weeds that may have appeared. The noxious weeds will be controlled per city policies and documented for the project tracking. Weed occurrences would be controlled by mechanical methods such as digging or whipping (the preferred method) or by hand application (wicking or backpack spraying) of a herbicide labeled for use in wetlands. 4.2.5 Overall Project Tracking In addition to the monitoring described above, overall project performance will be tracked by collecting information on public education and passive recreation feedback. Public opinion about recreational opportunities will be monitored in one or more ways that may include: a public opinion box installed at the gazebo, an annual meeting following each season to review the previous year and discuss the upcoming plans, and/or questionnaires (e.g., by email or via the e- letter updates). The purpose of the information gathering will be to gather feedback on perceived progress and assess visitor satisfaction. In addition to public perception, an internal review of the implementation plan will occur annually in order to be accountable for city staff and funding resources. Records of staff time will be recorded in a project log which will be submitted to the Parks Urban Resource Manager. A list of project contacts whose activities may need to be included in the effort and an example recordkeeping log are provided in the attachments. Capital expenses, maintenance and monitoring expenses, and consultant fees will also be documented for the project. At the end of each year and after 3 years, the number of hours contributed will be tabulated and compared to ©Biohabitats, Inc. *RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 AGENDA ITEM #_V`/l J 6 HA(. ite available records, e.g., for past years. This information will be helpful for preparing project accountability information to City Council and for preparing a maintenance budget and annual schedules. 5.0 SUMMARY Boulder City Parks and Recreation Department is conducting a three year program to add potable water to Thunderbird Lake as needed to increase the lake size and improve water quality. Because of the number of uncertainties associated with the project, this adaptive management plan has been prepared to outline the goals, management actions, monitoring, and response actions that will occur through May 2012. The plan is purposely intended to be flexible to allow for staff to experiment with the activities as new information becomes available. The monthly community updates will continue to be provided to interested parties and residents. Periodic project updates will also be provided to the Parks and Recreation Advisory Board. Year-end reports will be compiled assessing the various components of this project (financial, ecological, water quality, staff labor, etc.). After June 2012, the results of the project will be summarized and presented to City Council for their consideration about the continuation of the project. Oc iohabitats, Inc. *RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 / ArrzmnA ITPU tt t /'1(-A . PAGE LIST OF ATTACHMENTS - List of Project Contacts - Water Quality Monitoring Procedure - Activity Log - Memorandum of Understanding Authorizing Discharge from Thunderbird Lake (.pdf) 013iohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 AGENDA ITEM # o SAGE LIST OF PROJECT CONTACTS Contact&/Or Role Department/ Contact information Organization Matt Claussen/ City Parks and Recreation 303 413-7258 Urban Resource Manager Cell: 303-579-7492 claussenm@bouldercolorado.gov Joy Master/ Conservation City Parks and Recreation 303 413-7261 Ecologist masterj@bouldercolorado.gov 303 413-7402 Jim Shelley/ City of Boulder Utilities shelleyj@bouldercolorado.gov Water Quality Specialist 303-519-9394 W. Carey Sager/ City Parks and Recreation sagerc@bouldercolorado.gov Parks Maintenance Don Jenson/ City Parks and Recreation JensenD@bouIdercolorado.gov GIS Lisa Green/ Urban Parks City Parks and Recreation office: 303-441-3407 Manager 5200 Pearl St fax: 303-441-4061 Boulder, CO 80301 greenL@bouldercolorado.gov Katie Knapp/ City Planning and 303 441-3273 Wetland permit Development Services KnappK@bouldercolorado.gov administrator John Cogdill/ City Parks and Recreation 303-818-9818 Construction oversight cogdillj@bouldercolorado.gov Claudia Browne Biohabitats Inc. 303 477-0660 1731 Wazee St, Suite 209 cbrowne@biohabitats.com Denver, CO 80202 Jim Meining Aquatic and Wetland 303-442-4766 ext. 120 Nursery Manager Company Hmm a uaticandwetland.com 9999 CR 25 Fort Lupton, CO 80621 C fliohabitats, Inc. *RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • AGENDA ITEM # March 26, 2 GE -Vl{J1 9 Thunderbird Lake Water Quality Monitoring Procedure Assembled by Jim Shelley - City of Boulder, Water Quality Program This is a practical monitoring plan; its objective is to provide data and information useful in determining best management practices to meet project and community goals. Sampling o One deep water site, mid-dam and twenty five feet out from shoreline. o Sample monthly April through October. o Top sample collected in churn splitter. o Monitor vertical profile (pH, temperature, dissolved oxygen, specific conductance, depth) every 2/10th meter. o Record reservoir elevation and weather conditions at time of sampling. Parameter List Nutrients Total phosphorus Digestion SM4500-P B.5. Ascorbic Acid Method SM4500-P E. Dissolved phosphorus, Filtration Peristaltic pump .45 um. Digestion SM4500-P B.5 Ascorbic Acid Method SM4500-P E. Ortho phosphorus (IC) Nitrate Ion Chromatography (IC) Ammonia Microbiological Chlorophyll a, (Ethanol Extraction Method) Phytoplankton counts E. Coli, Idexx tray method Secchi disk depth ChemicaUphysical Field pH, Electrometric Method SM4500-H+ B Specific conductance, SM2510 B Estimate total dissolved solids (TDS) from specific conductance Dissolved oxygen (DO), Membrane Electrode Method SM4500-0 G Temperature, SM2550 B Reservoir profile with above field parameters Lab Total alkalinity, Titration Method SM2320 B. Total hardness, EDTA Titrimetric Method SM2340 C. CBiohabitats, Inc. eRESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • pp March 26, 200/9 0 `I •~rue~a YTrNG .13 1-/0l "#,-1 thy Turbidity, Nephelometric Method SM2130 B. Total suspended solids (TSS), SM2540 D. Sulfate (Ion Chromatography) Chloride (Ion Chromatography) General organic (Total organic Carbon) TOC, Persulfate-Ultraviolet Oxidation Method SM5310 C. Casts Sample bottle prep and Field sampling. Two people for four hours - one full time and one student work study ($35.00 per hour, total $140.00 per sample) Sample preservation and filtering One staff person for one hour ($25.00) Analysis and clean up One lab analyst for eight hours ($25.00 per hour, total $200.00 per sample) $445.00 Total cost per sample. Lab Analysis Metals ICPMS-5 sites, dissolved and total (x2), 4x per year, 18 metals---(720 analyses/yr) Hach dissolved iron and manganese-5 sites, 12x per year, 2 metals---(120 analyses/yr TOC---5 sites, 12x per year---(60 analyses/yr) Ion Chromatography (IC)---5 sites, 12x per year, 3 parameters---(180 analyses/yr) Chloride Sulfate Potassium TSS---5 sites, 12x per year----(60 analyses/yr) Turbidity---5 sites, 12x per year----(60 analyses/yr) Titrations 5 sites, 12x per year, 3 parameters-----(240 analyses/yr) Total hardness Calcium hardness Alkalinity MPA---1 site, 12x per year------(12 analyses/yr) Crypto/Giardia 1 site 12x per year, 1 site 4x per year-----(16 analyses/yr) Phytoplankton 2 sites, 12x per year----(24 analyses/yr) Chlorophyll a----2 sites, 12x per year----(24 analyses/yr) E coli---- 5 sites, 12x per year----(60 analyses/yr) Ammonia----1 site, 5x per year----(5 analyses/yr) Phosphorous--5 sites, 12x per year, 2 parameters----(120 analyses/yr) Total Dissolved ©Biohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 q5- AGENDA ITEM # Vf (-3 PAGE_. Nitrate---5 sites, 12x per year-----(60 analyses/yr) Total analyses-----1,701 Field Analyses Multiprobe (pH, temperature, specific conductance, dissolved oxygen, depth) with data logger required Field readings 5 sites, 4 parameters, 12x per year--=-(240 analyses/yr) Reservoir Profiles 1 site, 12x per year----(analyses vary depending on reservoir depth) Secchi disk 1site, 12x per year----(12 observations/yr) Thunderbird Lake Activity Loy COBlohabitats, Inc. •RESTORING THS EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 ~l+ AGENDA ITEM # .I 1-g u PAUx "b:,b Date: Person, Title/Organization: Other Persons Onsite: Description of Activity: Information shared with (list names): By (circle one): email phone conversation in person letter/submittal General Condition /Comments: Lake: Elevation is at or within 6 inches of target marker Yes _ No Water surface has <40% cover by duckweed and aquatic veg. Yes No Significant odors detected Yes No Water appears clear: Yes No Wetlands Mitigation Area: Signs of die back (explain) Yes _ No Signs of hydrology (gwater w/in 1 ft) Yes No Wildlife: Birds present include: Aquatic insects visible and include: Amphibians or reptiles visible and include: Public use: Describe uses while on site and any discussions with public: (OBiohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 ) /I r_Yl Ltd Noxious Weeds* / Problem Non-Native Plants Present (monitor during growing season): Bouncing bet Yes No Buckthorn Yes No *Canada thistle Yes _ No Chinese clematis Yes _ No _ *Diffuse knapweed Yes _ No *Leafy spurge Yes _ No *Musk thistle Yes No _ Myrtle spurge Yes No *Purple loosestrife Yes No *Russian knapweed Yes No Russian-olive Yes _ No _ Siberian elm Yes _ No _ *Spotted knapweed Yes _ No Tamarisk (salt cedar) Yes No *Yellow toadflax Yes No Other: Yes _ No If yes, list or describe: Comments: OBiohabitats, Inc. •RESTORING THE EARTH AND INSPIRING ECOLOGICAL STEWARDSHIP • March 26, 2009 AGENDA ITEM # V((~ a PAGE--X-f_ Attachment B f CITY OF BOULDER 7Planning and Development Services 1739 Broadway, Third Floor - P.O. Box 791, Boulder, CO 80306-0791 phone 303.441-1860 • fax 303-441-3241 • wet) boulderplandevelop.nel Wetland Kermit l Date Issued: 5/8!2009 Expiration Date: May 7, 2012 (Pursuant to Subsection 9-3-9(k), B.R.C. 1981) Y! Permit Number: LUR2009-00034 Contact Information CITY OF BOULDER PARKS AND REC 3196 BROADWAY i BOULDER, CO 80302 Project Information Location: 490 MOHAWK DR I Legal Description. LOT 2 EXC SLY 54.76 W BLK 7 FR ASTER MEADOWS MOHAWK a PAWNEE PARK PROPERTY ADDRESS: 000490 MOHAWK DR BOULDER Description of Work: WETLAND PERMIT for addition of potable water to Thunderbird Lake. l Three-year trial period. Conditions of Approval . The proposed projectlactivity is approved on the basis that it satisfies applicable requirements of Chapter 9-3-9, "Wetlands Protection," Boulder Revised Cade 1981. Other wetland requirements as set forth in Chapter 9-3-9 which are not specifically outlined in the conditions of approval below remain applicable to this projectlactivity. . The wetland permit is for a three-year trial management of Thunderbird Lake wllh routine additions of dechlorinated potable water. The permit also includes wetland mitigation and vegetation removal around the edges of the lake. The water shall be released in a manner to prevent erosion and minimize disturbance of sediment at the bottom of the lake. If the water additions will flow through the welland mitigation area prior to the establishment of wetland vegetation, additional soil stabilization measures will be required in order to protect newly seeded and planted areas. Best management practices shall be applied to all phases of the project and shall conform to the requirements of the "City of Boulder Wetlands Protection Program: Best Management Practices" adopted I July, 1995; and "City of Boulder Wetlands Protection Program: Best Management Practices - Revegetation Rules" adopted July, 1998. The welland mitigation site shall be monitored annually during the three-year trial period. Monitoring reports shall be submitted to the city of Boulder Planning and Development Services. If it is determined that the restoration is not successful, then corrective measures will need to be established and implemented to ensure a successful project. The following criteria shall be used to determine success: At least 80% native vegetative cover Invasive species on the Colorado Noxious Weed Inventory list-A shall be 100% eradicated. Invasive species on the Colorado Noxious Weed Inventory list-13 shall encompass no more than 100,6 of the total cover of the restoration area. Tree survival shall be 100%. AGENDA rr FE The water quality shall be monitored in accordance with the Thunderbird Lake Monitoring Plan. At a minimum, the following parameters shall be tested monthly from April through October: dissolved oxygen, water temperature, pH, phosphorus, nitrogen and water clarity (Secchi disk). Lake levels shall be monitored weekly during May through August and monthly from September through April in accordance with the draft Thunderbird Lake Adaptive Management Plan. Water shall be added as needed to maintain the established water surface elevation of 5314.0 - 5315.0 feet. If during the three-year trial period it is determined that a different approach is needed for the management of Thunderbird Lake, the weltand permit will need to be revised. At the end of the three-year trial period, a revised wetland permit application shall be submitted to Planning and Development Services for the long term management of Thunderbird Lake. Prior to installation, details and proposed locations of interpretive signs shall be submitted to Planning and Development Services. The applicant shall obtain a site inspection and approval from the City of Boulder Floodplain and Wetlands Administrator upon completion of the project. Inspections To schedule an inspection, call 303.441-3280 and refer to your permit number (LUR2009-00034). Wetland Mitigation Inspection Wetland Mitigation 2nd Year Wetland Mitigation 3rd Year Final Wetland Mitigation Insp _ fir, ATTACHMENT C TO: Alice Guthrie FROM: Ned Williams DATE: March 20, 2009 RE: Water Budget for Thunderbird Lake In accordance with city council's February 17, 2009 direction for Option D: Potable Water - multiple fills per year for Thunderbird Lake at Burke Park for a three year trial period and that staff return to council with ways to reduce the cost of this option, Utilities staff offers the following proposal to deal with the cost of potable water: I . Based on an estimated water surface area of 2.0 acres and an annual irrigation application rate of 15 gallons per square foot, an annual supplemental water budget of 1,307,000 gallons will be established for Thunderbird Lake for each year of 2009, 2010 and 2011. 2. The potable water for Thunderbird Lake will come from a fire hydrant for this three year trial period. Parks and Recreation will: a. rent a hydrant meter/backflow prevention assembly from Public Works Maintenance b. purchase all necessary hoses, de-chlorination boxes and de-chlorination tablets 3. Parks and Recreation may supply water to Thunderbird Lake from the fire hydrant beginning March 1 and ending November 30 of each year. The annual water budget of 1,307,000 gallons may be used during this 9-month period in the following seasonal manner: 588,000 gallons between March 1 and June 30, and 719,000 gallons between July 1 and November 30. Supplemental, potable water shall not be added to Thunderbird Lake in December, January or February. Other customers are provided a monthly water budget, but I think a seasonal water budget for this three-year trial period is appropriate. 4. Staff will track and monitor water use each month during this three year trial period. Parks and Recreation will not be charged for water use that does not exceed the 588,000 gallons of water budget amount for the period March 1 through June 30, or 719,000 gallons of water budget amount between July 1 and November 30, but will be charged for water use that exceeds this seasonal amount based on the rate structure and rate in effect for each year. For example, in 2009, the rate structure, rate and water budget (719,000 gallons) for Thunderbird Lake for the July 1 through November 30 season will be: Rate Water Budget Block (x 1,000 gallons (x 1,000 gallons 1 $ 2.06 0-431 2 $ 2.75 432 - 719 3 $ 5.50 720 - 1,079 4 $ 825 1,080- 1,438 5 $13.75 greater than 1,438 AGENDA ITEM # VI , PACE In December 2009, if 702,000 gallons of potable water was used for Thunderbird Lake between July 1 and November 30, Parks and Recreation would have no cost associated with the water use. However, if 1,380,000 gallons of potable water was used during this period, Parks and Recreation would have exceeded the seasonal water budget and would need to pay for the amount of water that was used over the annual budget. This amount of water is 661,000 gallons and the cost would be calculated as 360,000 gallons at Block 3 rate ($5.50) plus 301,000 gallons at Block 4 rate ($8.25), for a total cost of $4,463.25. of BO&4 3198 Broadway • Boulder, Colorado 80304-2644 Tel. 303-413-7200 • Fax 303-413-7201 www.bouldercolorado.gov/parks-recreation Parks & Recreation MEMORANDUM TO: Jane Brautigam, City Manager Paul Fetherston, Deputy CityManager FROM: Kirk Kincannon, Director of Parks and Recreation Maureen Rait, Executive Director of Public Works Ned Williams, Director of Public Works for Utilities ` r)l c.) Felix Gallo, Parks and Planning Interim Superintendent Matt Claussen, Urban Resource Manager, Parks and Recreation SUBJECT: Interdepartmental Memorandum of Understanding Authorizing Discharges from Thunderbird Lake to the Storm Water Utility System DATE: October 27, 2009 Attached is a Memorandum of Understanding between the Parks and Recreation Department and the Department of Public Works describing the specifics of discharging water from Thunderbird Lake into the city of Boulder storm water utility system The City Attorney's Office has recommended that the authorization to permit discharge from Thunderbird Lake to Municipal Separate Storm Sewer System (MS4) be documented administratively in the form of a Memorandum of Understanding, ("MOLT") between the City departments and approved by the city manager. In order to provide some background information to assist in the understanding of this memorandum and the project management relating to Thunderbird Lake, several issues that are pertinent to this memorandum are briefly answered below with acknowledgement of existing documentation that provides further detailed information, should it be necessary. City Council Action At the Feb. 17, 2009 City Council meeting, council approved (vote was 6-2 in favor) a motion to adopt Option D: Potable Water - Multiple Fills per year, as described in the agenda memo, with additional conditions that require 1) a check in in three (3) years to determine whether the management plan is working, 2) staff to provide a reduced cost scenario for how to accomplish this management plan, and 3) staff to provide a cost analysis on vegetation management. Wetland Permit A city of Boulder wetland permit was issued on May 22, 2009. The wetland permit addressed the project issues of necessary mitigation, specific permit conditions, impacts resulting from addition of l AGENDA ITEM # ~~I-~ F PAGE 52, Of BOOZ 3198 Broadway • Boulder, Colorado 80304-2644 ON f i Tel. 303-413-7200 • Fax 303-413-7201 www.bouldereolorado.gov/parks-recreation Parks & Recreation water, establishment of wetland vegetation, weed control, best management practices relating to wetland protection and tirnefrarne of the wetland permit. Land Management Activities and Programs An Adaptive Management Plan (Plan) has been written as a guiding document to articulate management and monitoring practices over the next three years (June 2009 - June 2012). This Plan is scheduled for Park and Recreation Advisory Board consideration in November of 2009, but implementations of certain components of the plan have been initiated. The Plan has been written in coordination with the wetland consultants Biohabitats, Inc. and details the management activities of the Thunderbird Lake Project. This includes; - General introduction and background information - Purpose of the plan, goals and objectives - Water level management (includes outflow/discharge of water) - Water qualityimprovement - Wetland mitigation - Ongoing maintenance and activities - Overview of monitoring plan - Monitoring procedures and recordkeeping Briefly, the four primary goals of the project are; 1. Increase the lake surface area to approximately 2.2 acres (water elevation of 5,315 ft); 2. Improve the water quality of Thunderbird Lake; 3. Minimize the changes in wetland function and aquatic habitat; and, 4. Provide opportunities for education and passive recreation. Water Dclivery The Plan addresses the manner in which water will be delivered to the lake. The main venue is via the existing irrigation system, that has been retrofitted to account for a separate water meter, dechlorination process and flow into the lake that eliminates the potential for erosion or excessive disturbance to sediments. An annual water budget of 1,307,000 gallons has been provided for this project and any overuse of this budget will be subject to the block rates in effect at the time for water used in excess of the annual water budget and payment to the Water Utility Fund will be the responsibility of Parks and Recreation. City Ordinances Regulating Storm Water Discharges Water that is released from Thunderbird Lake as part of a flow-through coordination will enter the city storm water system. The specific ordinance regulating this type of activity is described below. Pursuant to section 11-5-5, "Discharges to the Storm Water Utility System," B.Rc 1981, discharges are prohibited unless authorized by the city manager. !AGENDA ITEM # V~ "~j ,DACE 3 oV- B0&l 3198 Broadway - Boulder, Colorado 80304-2644 . Tel. 303-413-7200 - Fax 303-413-7201 ~rl 1-11 ,Ii www.bouldercolorado.gov/parks-recreation Parks & Recreation 11-5-5 Discharges to the Storm Water Utility System. (a) Discharges Prohibited: No user or other person shall discharge any sewage, other polluted waters, or other deleterious substance from any premises within the city into or upon any public highway, street, sidewalk, alley, land, public place, stream, ditch, or other watercourse or into any cesspool, storm or private sewer, or natural water outlet, except where suitable treatment has been provided in accordance with provisions of applicable federal, state, and local laws... . (d) Exemptions: The following discharges are exempt from the discharge permit requirements established by this chapter. (2) Any discharge that is authorized by the city manager. Rcportinje During and at Conclusion of Proi ct Public monthly updates continue to be sent out via electronic and postal mail. Periodic updates to the Parks and Recreation Advisory Board have been occurring and a Weekly Information Packet is being assembled for City Council. Annual reports detailing the maintenance activities, monthly water quality monitoring, staff time and expenditures, etc. will be provided to the Park and Recreation Advisory Board (PRAB). By June 2012, which is the end of the project term, a final report will be provided to PRAB to determine the next steps of this project. If requested, recommendations from staff will be provided to City Council as to the future of Management Plan for Thunderbird Lake, including the use of potable water to aid in filling the Thunderbird Lake and the discharging of water from Thunderbird Lake into the storm water utility system. Additional Information The documents that provide additional background details are available upon request; - Wetland Permit LUR2009-00034 - Thunderbird Lake Adaptive Management Plan June 2009 June 2012 (Draft) - Thunderbird Lake Monitoring Plan - Water Quality - Thunderbird Lake Project Cost Analysis - State of Colorado Low Risk Discharge Policy City staff has contacted the appropriate representative (s) from Dry Creek Number 2 Ditch, which is part of the storm water system conveyance route, for water discharged from Thunderbird Lake. Recognition of this project and approval for any discharge has been received. For the Wellman Ditch along this route, there are no impacts or approval requirements necessary. 3 AGENDA ITEM # Vit-b , PAGl=_2i_ MEMORANDUM OF UNDERSTANDING FOR THUNDERBIRD LAKE AT THE BURKE PARK LOCATION Mohawk Dr. & Pawnee Dr. TO: Jane Brautigam, City Manager Paul Fetherston, Deputy City Manager FROM: Kirk Kincannon, Director ofParks and Recreation Maureen Rait, Executive Director of Public Works Ned Williams, Director of Public Works for Utilities Felix Gallo, Parks and Planning Interim Superintendent Matt Claussen, Urban Resource Manager, Parks and Recreation SUBJECT. Interdepartmental Memorandum of Understanding Authorizing Discharges from Thunderbird Lake to the Storm Water Utility System DATE: October 27, 2009 Pro e : The City of Boulder (the "City") owns the property, commonly referred to as Thunderbird Lake, located in Burke Park at Mohawk Drive and Pawnee Drive, Boulder Colorado. Documentation of the Permit Approval: The Parks and Recreation Department is requesting permission to discharge surface water and dechlorinated potable water from Thunderbird Lake to the City storm sewer system, which is regulated by the state issued Municipal Separate Storm Sewer System (MS4) permit. In order to assure that the discharge of Thunderbird Lake proceeds under the terms of the permit authorization and pursuant to the relevant laws in this area, the Parks and Recreation Department and the Public Works Department agree to the following terms and conditions: 1. Thunderbird Lake shall be filled to desired levels with potable water from Citywater services, according to best management practices and dechlorination procedures. The intent of the City departments is to fill Thunderbird Lake and remove a portion of stagnant water currently in the lake through dilution and routing the lake overflow into the City's storm sewer system through the existing Thunderbird Lake overflow structure. 2. All applicable laws and regulations are followed as described by the Colorado Department of Public Health and Environment (CDPHE) in accordance with the Colorado Department of Public Health and Environment L owRisk Disdba7 Gmdanc Potable Water, May 2009 (see attached). 3. The maximum flow rate capacity shall be determined at the outlets of Thunderbird Lake to the storm system (MS4) and at all times during the filling and daily flow AGENDA ITEM # V(( ^ p PAGE 5 operations of Thunderbird Lake, the flow rate of incoming water (potable hydrant/irrigation water and natural sources) shall not exceed the lake outlet maximum flow rate capacity. 4. All discharges to the City's storm sewer system must comply with section 11-5-5, B.R.C. 1981 (see attached). 5. Removal of any residual chlorine must be done for any direct discharge to state surface waters, or for any discharge to a storm sewer or conveyance where the chlorine will not dissipate prior to reaching a state surface water. Dechlorination, if necessary, may be achieved by allowing water to stand uncovered until no chlorine is detected, or by dechlorination using a portable dechlorinator, or an installed dechlorination chamber. Pay particular attention when handling super-chlorinated waters. A longer time is needed to dissipate chlorine from super-chlorinated waters. 6. The discharge should be conducted to minimize the potential to pick up additional suspended solids. When possible, a best management practice, or combination of practices, for filtering or settling suspended solids and other debris, or a combination of practices, should be used to remove suspended solids or other debris. Examples of suspended solid removal practices include, but are not limited to check dams, filter bags, and inlet protection. These devices should be used and maintained in accordance with the manufacturers specifications. This MOU constitutes approval to discharge the surface water to the City storm sewer system provided the above conditions are met. This permission is granted pursuant to section 11-5-5(d)(2) B.R.C. 1981, and applies to the described discharges beginning June 2009 and ending June 2012, and does not relieve the Parks and Recreation Department of the responsibility to meet any other applicable requirements or conditions of any local, state or federal regulations. Permission to use the City's storm sewer system can be revoked at anytime, for any reason. The City will be subject to enforcement actions, including fines or penalties, if hazardous, toxic or inhibitory conditions occur due to any discharge. It should be noted that the discharge from Thunderbird Lake may enter the Dry Creek Number 2 Ditch, which is the receiving water from the overflow structure. This MOU does not grant permission to use the Dry Creek Number 2 Ditch or any other privately owned waterway unless authorized by the appropriate representatives. Contact with Dry Creek # 2 representatives will be made by city staff before any discharge will occur. Third Party Beneficiaries: This MOU is intended to document an arrangement between City departments and shall not create any third party beneficiaries. I APPROVE THIS ARRANGEMENT on this ~ day of , 200 Jane Brautigam, City Maner ATTEST: APPROVED AS TO FORM: r ~1t C: erk ~orn -)eh~ilf of tli Atcorne Y Y Director of Finance and IC rd AG1r)1ITEM # U I PAGE b Attachment D ~4 Of BO(JZ 3198 Broadway - Boulder, Colorado 80304-2644 , rr(>It- Tel. 303-413-7200 - Fax 303-413-7201 www.bouldereolorado.gov/parks-recreation Parks & Recreation MEMORANDUM TO: Jane Brautigam, City Manager Paul Fetherston, Deputy City Manager FROM: Kirk Kincannon, Director of Parks and Recreation Maureen Rait, Executive Director of Public Works Ned V rdliams, Director of Public Works for Utilities `7' 6A') Felix Gallo, Parks and Planning Interim Superintendent Matt Claussen, Urban Resource Manager, Parks and Recreation SUBJECT: Interdepartmental Memorandum of Understanding Authorizing Discharges from Thunderbird Lake to the Storm Water Utility System DATE: October 27, 2009 Attached is a Memorandum of Understanding between the Parks and Recreation Department and the Department of Public Works describing the specifics of discharging water from Thunderbird Lake into the city of Boulder storm water utility system. The CityAttomey's Office has recommended that the authorization to permit discharge from Thunderbird Lake to Municipal Separate Storm Sewer System (MS4) be documented administratively in the form of a Memorandum of Understanding, ("MOLT') between the City departments and approved by the city manager. In order to provide some background information to assist in the understanding of this memorandum and the project management relating to Thunderbird Lake, several issues that are pertinent to this memorandum are briefly answered below with acknowledgement of existing documentation that provides further detailed information, should it be necessary. City Council Action At the Feb. 17, 2009 City Council meeting, council approved (vote was 6-2 in favor) a motion to adopt Option D: Potable Water - Multiple Fills per year, as described in the agenda memo, with additional conditions that require 1) a check-in in three (3) years to determine whether the management plan is working, 2) staff to provide a reduced cost scenario for how to accomplish this management plan, and 3) staff to provide a cost analysis on vegetation management. Wetland Permit A city of Boulder wetland permit was issued on May 22, 2009. The wetland permit addressed the project issues of necessary mitigation, specific permit conditions, impacts resulting from addition of 1 AGENDA ITEM # Vld~~ ~ pA.GF ~ 1 Of 1300 't r 3198 Broadway • Boulder, Colorado 80304-2644 f , f Tel. 303-413-7200 • Fax 303-413-7201 www.bouldereolorado.gov/parks-recreation Parks & Recreation water, establishment of wetland vegetation, weed control, best management practices relating to wetland protection and timeframe of the wetland permit. Land Management Activities and Programs An Adaptive Management Plan (Plan) has been written as a guiding document to articulate management and monitoring practices over the next three years (June 2009 - June 2012). This Plan is scheduled for Park and Recreation Advisory Board consideration in November of 2009, but implementations of certain components of the plan have been initiated. The Plan has been written in coordination with the wetland consultants Biohabitats, Inc. and details the management activities of the Thunderbird Lake Project. This includes; General introduction and background information Purpose of the plan, goals and objectives Water level management (includes outflow/discharge of water) Water quality improvement Wetland mitigation Ongoing maintenance and activities Overview of monitoring plan - Monitoring procedures and recordkeeping Briefly, the four primary goals of the project are; 1. Increase the lake surface area to approximately 2.2 acres (water elevation of 5,315 ft); 2. Improve the water quality of Thunderbird Lake-, 3. Minimize the changes in wetland function and aquatic habitat; and, 4. Provide opportunities for education and passive recreation. Water Delivery The Plan addresses the manner in which water will be delivered to the lake. The main venue is via the existing irrigation system, that has been retrofitted to account for a separate water meter, dechlorination process and flow into the lake that eliminates the potential for erosion or excessive disturbance to sediments. An annual water budget of 1,307,000 gallons has been provided for this project and any overuse of this budget will be subject to the block rates in effect at the time for water used in excess of the annual water budget and payment to the Water Utility Fund will be the responsibility of Parks and Recreation. City Ordinances Regulating Storm Water Discharges Water that is released from Thunderbird Lake as part of a flow-through coordination will enter the city storm water system. The specific ordinance regulating this type of activity is described below. Pursuant to section 11-5-5, "Discharges to the Storm Water Utility System," B.KC. 1981, discharges are prohibited unless authorizes( by the city manager. -2 .AGENDAlT_FMAV11_0__,PAGE 59 OF BOtft~F 3198 Broadway • Boulder, Colorado 80304-2644 Tel. 303-413-7200 • Fax 303-413-7201 www.bouldercolorado.gov/parks-recreation Parks & Recreation 11-5-5 Discharges to the Storm Water Utility System. (a) Discharges Prohibited: No user or other person shall discharge any sewage, other polluted waters, or other deleterious substance from any premises within the city into or upon any public highway, street, sidewalk, alley, land, public place, stream, ditch, or other watercourse or into any cesspool, storm or private sewer, or natural water outlet, except where suitable treatment has been provided in accordance with provisions of applicable federal, state, and local laws... . (d) Exemptions: The following discharges are exempt from the discharge permit requirements established by this chapter. (2) Any discharge that is authorized by the city manager. Reporting During and at Conclusion of Proiect Public monthly updates continue to be sent out via electronic and postal mail. Periodic updates to the Parks and Recreation Advisory Board have been occurring and a Weekly Information Packet is being assembled for City Council. Annual reports detailing the maintenance activities, monthly water quality monitoring, staff time and expenditures, etc. will be provided to the Park and Recreation Advisory Board (PRAB). By June 2012, which is the end of the project term, a final report will be provided to PRAB to determine the next steps of this project. If requested, recommendations from staff will be provided to City Council as to the future of Management Plan for Thunderbird Lake, including the use of potable water to aid in filling the Thunderbird Lake and the discharging of water from Thunderbird Lake into the storm water utility system. Additional Information The documents that provide additional background details are available upon request; - Wetland Permit LUR2009-00034 - Thunderbird Lake Adaptive Management Plan June 2009 June 2012 (Draft) - Thunderbird Lake Monitoring Plan - Water Quality - Thunderbird Lake Project Cost Analysis - State of Colorado Low Risk Discharge Policy City staff has contacted the appropriate representative (s) from Dry Creek Number 2 Ditch, which is part of the storm water system conveyance route, for water discharged from Thunderbird Lake. Recognition of this project and approval for any discharge has been received. For the Wellman Ditch along this route, there are no impacts or approval requirements necessary. 3 AGENDA ffEM 0 Oj PAGE MEMORANDUM OF UNDERSTANDING FOR THUNDERBIRD LAKE AT THE BURKE PARK LOCATION Mohawk Dr. & Pawnee Dr. TO: Jane Brautigam, City Manager Paul Fetherston, Deputy CityManager FROM: Kirk Kincannon, Director ofParks and Recreation Maureen Rait, Executive Director of Public Works Ned Williams, Director of Public Works for Utilities Felix Gallo, Parks and Planning Interim Superintendent Matt Claussen, Urban Resource Manager, Parks and Recreation SUBJECT: Interdepartmental Memorandum of Understanding Authorizing Discharges from Thunderbird Lake to the Storm Water Utility System DATE: October 27, 2009 Pro e The City of Boulder (the "City") owns the property, commonly referred to as Thunderbird Lake, located in Burke Park at Mohawk Drive and Pawnee Drive, Boulder Colorado. Documentation of the Permit Approval: The Parks and Recreation Department is requesting permission to discharge surface water and dechlorinated potable water from Thunderbird Lake to the City storm sewer system, which is regulated by the state issued Municipal Separate Storm Sewer System (NIS4) permit. In order to assure that the discharge of Thunderbird Lake proceeds under the terms of the pen-nit authorization and pursuant to the relevant laws in this area, the Parks and Recreation Department and the Public Works Department agree to the following terms and conditions: 1. Thunderbird Lake shall be filled to desired levels with potable water from City water services, according to best management practices and dechlorination procedures. The intent of the City departments is to fill Thunderbird Lake and remove a portion of stagnant water currently in the lake through dilution and routing the lake overflow into the City's storm sewer system through the existing Thunderbird Lake overflow structure. 2. All applicable laws and regulations are followed as described by the Colorado Department of Public Health and Environment (CDPHE) in accordance with the Colorado Department of Public health and Environment LawRisk Dis&a7 Gudanc Potable Water, May 2009 (see attached). 3. The maximum flow rate capacity shall be determined at the outlets of Thunderbird Lake to the storm system 04) and at all times during the filling and daily flow AGENDA ITEM # -b , l~'~GE o operations of Thunderbird Lake, the flow rate of incoming water (potable hydrant/irrigation water and natural sources) shall not exceed the lake outlet maximum flow rate capacity. 4. All discharges to the City's storm sewer system must comply with section 11-5-5, B.KC. 1981 (see attached). 5. Removal of any residual chlorine must be done for any direct discharge to state surface waters, or for any discharge to a storm sewer or conveyance where the chlorine will not dissipate prior to reaching a state surface water. Dechlorination, if necessary, may be achieved by allowing water to stand uncovered until no chlorine is detected, or by dechlorination using a portable dechlorinator, or an installed dechlorination chamber. Pay particular attention when handling super-chlorinated waters. A longer time is needed to dissipate chlorine from super-chlorinated waters. 6. The discharge should be conducted to minimize the potential to pickup additional suspended solids. When possible, a best management practice, or combination of practices, for filtering or settling suspended solids and other debris, or a combination of practices, should be used to remove suspended solids or other debris. Examples of suspended solid removal practices include, but are not limited to check dams, filter bags, and inlet protection. These devices should be used and maintained in accordance with the manufacturers specifications. This MOU constitutes approval to discharge the surface water to the City storm sewer system provided the above conditions are met. This permission is granted pursuant to section 11-5-5(d)(2) B.R-C. 1981, and applies to the described discharges beginning June 2009 and ending June 2012, and does not relieve the Parks and Recreation Department of the responsibility to meet any other applicable requirements or conditions of any local, state or federal regulations. Permission to use the City's storm sewer system can be revoked at anytime, for any reason. The City will be subject to enforcement actions, including fines or penalties, if hazardous, toxic or inhibitory conditions occur due to any discharge. It should be noted that the discharge from Thunderbird Lake may enter the Dry Creek Number 2 Ditch, which is the receiving water from the overflow structure. This MOU does not grant permission to use the Dry Creek Number 2 Ditch or any other privately owned waterway unless authorized by the appropriate representatives. Contact with Dry Creek # 2 representatives will be made by city staff before any discharge will occur. Third Party Beneficiaries: This MOU is intended to document an arrangement between City departments and shall not create any third parry beneficiaries. I APPROVE THIS ARRANGEMENT on this M day of , 200 , Jane Brautigam, CityNlan er ATTEST: APPROVED AS TO FORM: City C. crEc on Feh<ill of 111 *AAttomey Director of Finance and 'c rd AGENDA f TIEM 4V11--, WAGE"!-_ Attachment E Biobabitats v.l'i tll Yt tl FlAl VIN ~I..I~ 61•.YI I.II•~ r - nr. . rrrt MEMORANDUM To: Matt Claussen, City of Boulder Parks and Recreation From: Claudia Browne, Biohabitats Inc. Date: February 12, 2010 Re: Thunderbird Lake-Annual Groundwater Monitoring Purpose The purpose of this memorandum is to describe the groundwater related work completed in 2009 and to provide the results of water level monitoring conducted for the Thunderbird Lake adaptive management plan. Per our letter of March 20, 2009, the scope of work focused on collection and maintenance of the data and did not include a detailed groundwater data analysis. Detailed descriptions of the groundwater well constructions and methods are presented in the Groundwater Monitoring Plan dated February, 2009. As described in the Adaptive Management Plan for 2009-2012, the purpose of the groundwater elevation data is to assist in understanding the relationship between lake levels and the water table as well as to better understand the relationship between precipitation and tile drain inflow to groundwater levels. Monitoring Well Permits Nine monitoring wells were installed in the vicinity of Thunderbird Lake in Spring 2008 with temporary well permits from the State Engineers Office. (Map of well locations attached.) In April 2009, Biohabitats prepared and submitted applications for the permanent well permits which needed to be completed within one year of their installation. Copies of the State permits were received by Biohabitats in May 2009. These permits replaced the temporary use permits which were due to expire the first week in April 2009. Hard copies of the permits will be provided to the City for its records (to be delivered at our next meeting), Data Collection & Summary Biohabitats visited the site on two occasions - in July and December- to download data loggers.' Please note that heavy snow cover made it difficult to locate the flush mount well boxes in December (as a result, no data were collected from MW6 or MW9' however, these well locations are represented by nearby wells MW 1 and MW 7). MW5 remained dry through the monitoring period. Following logger downloads, the pressure data were then processed using Hoboware software provided by the manufacturer to obtain elevations. The water elevation data were then exported into Excel spreadsheets. Data were reviewed to identify any equipment errors or anomalous readings indicative of a malfunction. Minor anomalies were corrected as needed, and the results were graphed. The attached hydrographs present the water elevations of the lake, all wells combined, and individual monitoring wells. General observations are provided below: • MW 3 and MW4 -closest to the lake- show the greatest seasonal fluctuation in comparison to wells located at a further distance from the lake. 1 A follow-up visit occurred in January 2010 to extract the surface water logger from the ice in the lake by using hot water to melt it out. AGENDA, ITEM # ~l~'~ ~ PAGF_ 6?, • Well clusters or pairs (MW1 and MW7; and MW9 and MW6) share general hydrograph patterns and trends, as expected given their close proximity. • In 2009, peak elevations occurred in the Spring, and minimum elevations occurred in the Fall. While in 2008, maximum groundwater elevations occurred during the Fall; and minimum groundwater elevations were recorded in the Winter. • Groundwater levels in MW 2- located upgradient of the lake- show that the groundwater level was about a foot higher in the spring of 2009 compared to 2008. Based on our cursory review of the inflow records, groundwater levels were not high enough or for a sustained enough period to significantly increase tile drain inflows. • In all wells, groundwater levels spiked on 4/19/09 in response to a large rain event when nearly 4 inches of precipitation were recorded in two days.2 The water level in the lake also rose significantly following the April storm event. Data Limitations Biohabitats did not collect or review climate data as part of this data collection effort except as needed to understand the April 2009 spikes in the water level readings. Therefore, we have not compared the groundwater and lake information to precipitation records to allow us to provide more detail on trends during the monitoring period. Biohabitats also did not evaluate the water budget or how lake levels responded to the additions of potable water which occurred through the new irrigation system in 2009. Our understanding is that the equipment issues associated with the dechlorination unit limited the amount of inflow, and prevented the City from achieving the desired fill levels in 2009. We did have discussions with the technical support representatives of the Hobo loggers to discuss inconsistencies in the pressure data. According to the manufacturer, the pressure transducer loggers are subject to error if they are not sufficiently vented. To reduce errors in 2010, we suggest 1) moving the barometric logger to another well where it is less likely to get wet should the water table rise significantly, and 2) drilling additional holes in the top in the irrigation boxes to improve venting 2 The barometric logger-- normally suspended in air in MW3-showed erratic readings that suggest that it may have gotten wet during the April storm and affected the accuracy of the readings during that time. AGENDA ITEM # Vf ~ I PAGE _ Groundwater Monitoring Wells Thunderbird Lake at Admiral Burke Park r ;;p ` S r,- - ♦ Y, h^ - - j L• F ya : r.:. L; 191" If ^ _ _ f L S y~•-~ DIY i - - tR~ ti~ ~ ~ R~'- of - i ~~:l: ~ *'t• c,,,c .-r t r . V- 414 lov % i~ f N Basemap Source- Feet USGS 7.5 minute Topographic Map 0 250 500 1,000 w E Louisville, CO, 1994 rvsd s 1 Thunderbird Lake Groundwater Wells (no MW8) June 08 - December 09 5324 p April 17 2.59" April 18 1 1 " MW 1 5322 MW 2 5320 MW 3 5318 MW 4 5316 mws mw7 5314 - " 8 MW rn 9 ® 5312 - Nil I 5310 10-Jun-08 18-Sep-08 27-Dec-08 6-Apr-09 15-Jul-09 23-Oct-09 31-Jan-10 D a7 m Thunderbird Lake Wafer Levels 5316 June 2008-December 2009 i 5315 - - - - - --I 5314 - 5313 ■ - Data Logger 5312 - - Manual asure 5311 ,T.. 00 0o ao 00 00 00 00 0o rn ~ rn ~ ~ rn rn a~ rn rn rn rn O O O O O O O O o 0 0 0 0 0 0 0 0 0 0 0 O O O O O O O O O O O O O O O O O O O O N N N N N N N N N N N N N N N N N N N N W 1~ C~ O O m CO (4 M lf) N O w m m O O w C_~? N N N N N N N N = 1 = O N O O r N 'r- N m t lf3 Co 1- M O r- Note: Erratic peaks and drops-betw een 92-08 and 3-08 likely due to logger error. m z v 74 m x 9- s m MW1 Groundwater Elevations (ft) 5318.4 June 2008-December 2009 5318.2 5318 5317.8 5317.6 A.. L 5317.4 5317.2 5317 5316.8 z 5316.6 D I > 5316.4 8-Jun-08 16-Sep-08 25-Dec-08 4-Apr-09 13-Jul-09 21-Oct-09 29-Jan-10 I~ v MW2 Groundwater Elevations (ft) June 2008-December 2009 5318 5317.5 5317 5316.5 5316 5315.5 5315 z 5314.5 =n 5314 9 Vc. 5313.5 8-Jun-08 16-Sep-08 25-Dec-08 4-Apr-09 13-Jul-09 21-Oct-09 29-Jan-10 MW3 Groundwater Elevations (ft) June 2008-December 2009 5316 - ,i__~_ 5315.5 5315 5314.5 5314 5313.5 5313 5312.5 5312 5311.5 5311 5310.5 8-Jun-08 16-Sep-08 25-Dec-08 4-Apr-09 13-Jul-09 21-Oct-09 29-Jan-10 0 er-, MW4 Groundwater Elevations (ft) 5321.00 June 2008-July 2009 5320.00 5319.00 5318.00 5317.00 5316.00 5315.00 5314.00 5313.00 5312.00 ® 5311.00 D 8-Jun-08 25-Dec-08 13-Jul-09 29-Jan-10 MW 6 Groundwater Elevations (it) June 2008-July 2009 5321.00 - 5320.00 f 5319.00 I 5318.00 5317.00 5316.00 i 5315.00 rjFw%~ 4 I 5314.00 G) a m Q 5313.00 m 5312.00 # 5311.00 8-Jun-08 28-Jul-08 16-Sep-08 5-Nov-08 25-Dec-08 13-Feb-09 4-Apr-09 24-May-09 13-Jul-09 IN r--1 MW7 Groundwater Elevations (ft) June 2008-December 2009 5323.5 - - 5323 5322.5 5322 5321.5 y rn z D 5321 8-Jun-08 25-Dec-08 13-Jul-09 29-Jan-10 MW8 Groundwater Elevations (ft) June 2008-December 2009 5345 - - - 5344 5343 5342 i 5341 m z v 5340 6/8/2008 9/16/2008 12/25/2008 4/4/2009 7/13/2009 10121/2009 1/29/2010 1_ i~ MW9 Groundwater Elevations (ft) June 2008-July 2009 5324 - 5323.5 5323 5322.5 m 5322 8-Jun-08 16-Sep-08 25-Dec-08 4-Apr-09 13-Jul-09 t Attachment F Thunderbird Lake: Water Quality Data Collection Summary 2009 (Brief explanation begins each category. Results from Thunderbird Lake data collections are bulleted.) Dissolved oxygen The oxygen dissolved in lakes, rivers, and oceans is crucial for the organisms and creatures living in it. As the amount of dissolved oxygen drops below normal levels in water bodies, the water quality is harmed and creatures begin to die off. Indeed, a water body can "die", a process called eutrophication. Rapidly moving water, such as in a mountain stream or large river, tends to contain a lot of dissolved oxygen, while stagnant water contains little. Bacteria in water can consume oxygen as organic matter decays. Thus, excess organic material in our lakes and rivers can cause an oxygen-deficient situation to occur. Aquatic life can have a hard time in stagnant water that has a lot of rotting, organic material in it, especially in summer, when dissolved-oxygen levels are at a seasonal low. • The majority of dissolved oxygen profile readings were below the warm water oxygen criteria of 5 mg/L during the June, July, August and September sample dates. • Dissolved oxygen and pH profile curves appear to correlate with each other. This indicates that more photosynthesis was occurring at the depths where peaks occur for both of these field parameters. • On July 7, very low dissolved oxygen was observed throughout the vertical water column, these low oxygen concentrations were caused by the attempt to remove floating vegetation. The nets used dislodged rooted aquatic plants thus disturbing the sediments and bringing low dissolved oxygen water to the surface. A sulfide smell was present during this maintenance operation. Reduced dissolved manganese was also high in the surface water during this sample event. PH pH is a measure of how acidic/basic water is. The range goes from 0 - 14, with 7 being neutral. pHs of less than 7 indicate acidity, whereas a pH of greater than 7 indicates a base. • All pH profile values were within the 6.5 to 9.0 criteria range. • June through September lower pH values near the bottom are due to reduced low oxygen conditions. Specific Conductance Specific conductance is a measure of the ability of water to conduct an electrical current. It is highly dependent on the amount of dissolved solids (such as salt) in the water. Pure water, such as distilled water, will have a very low specific conductance, and sea water will have a high specific conductance. Rainwater often dissolves airborne gasses and AGENDA ITEM ~ ~ll ~ PARt 7 airborne dust while it is in the air, and thus often has a higher specific conductance than distilled water. Specific conductance is an important water-quality measurement because it gives a good idea of the amount of dissolved material in the water. • Specific conductance decreased from 1460 to 568 umhos/cm between April 28 and October 6. This change is primarily due to the addition of low conductance finished distribution system (potable) water throughout the summer. • Specific conductance and estimated total dissolved solids on October 6 dropped below the 500 mg/L and 820 umhos/cm criteria levels. • Sulfate was observed below the 250 mg/L criteria on October 6. • Hardness and Alkalinity decrease from 325 and 150 mg/L to 161 and 114 mg/L respectively. Chloride dropped from 131 to 49 mg/L. Temperature Temperature also can affect the ability of water to hold oxygen as well as the ability of organisms to resist certain pollutants. • Temperature values stayed below the upper chronic criteria of 26.5 °C for warm water lakes. Other Interesting Results: • Total phosphorous decreased below 100 ug/L but still exceeded the 60 ug/L criteria limit • The only time chlorophyll a peaked above the 20 ug/L criteria was on September 9 (20.5 ug/L). • E-coli exceeded the 126/100mis criteria two times on August 13 (326/100mis) and July 7 (261 /1 00mis). • Very low nitrate data between June 1 and October 6 indicate a nitrogen limited situation. Although ortho-phosphorous was low, there's plenty dissolved phosphorous present for phytoplankton to utilize. AGENDA ITEM n PAGE, Thunderbird Lake Dissolved Oxygen Profiles (2009) 0 Sample Dates 0.2 --'V - - - - _ -+41as1 - 514 0.4 611 ; - e-. 717 _ 814 0.6 1 - - i-819 ~i-1016 ~I E 0.8 CL 4) 1 Oxygen Criteria 1.2 - - I I I 1.4 u 1.6 1.8 0 1 2 3 4 5 6 7 $ 9 1D 11 12 13 14 15 Dissolved Oxygen (mg1l-) Thunderbird Lake pH Profiles (2009) 0 Sample Dates Y 0.2 -4--4128 j El S14 0.4 6fl W7 814 - 0.6 I -+--1016 j 1.2 - - - - 1.4 - - - - air/ - - - - - - - - _ 1.6 1.8 6 6.5 7 7.6 8 8.6 9 pH (su) AGENDA ITEM # V11 r _ 0 PAGE- I Thunderbird Lake Specfic Conductance Profiles (2009) a - - - - Sample Dateal 0.2 - - - 4126 -m--614 0.4 - - - Bl1 7r7 814 0.6 - - - - - f-fl19- -.*-10f6 - - - - - - - E 0.8 a k 1.2 1.4 Sao 700 900 1100 1300 1500 1700 Specific Conductance (umhoslcm) Thunderbird Lake Temperature Profiles (2009) 0 - L 0.2 ! 1 0.4 - 1 I / 0.6 - - Sample Dates +4r28 0.8 - - - --W-6f4 _ 011 06 76 ° 814 919 1A r~ 1.8 10 12 14 16 18 20 22 24 Temperature (°C) AGENDA ITEM # Y f ~ , ?AGE ATTACHMENT G orto"zostir:vul ReVleed Coal Figures Eadnide Estlmatod Ffitlmatod OpWn D - Potable 9Vater-- mu$11 rifle per year Look V' ' 2008 Estimate 2009 Actual Able 2010 2011 Project Total Costs associated with Initial set-upfcapkal Investment 777:= 1 Contractual costs for management plan, mitigation plan, groundwater monitoring $20.829 $20,578 $500 S500 520,829 Hydrant (If ParksJRsaeallon had to purchase all necessary equipment). s0 $0 $0,310 5540 1 $0 30 $6.850 Community education d outreach titt,s00 $10,000 $0 $02 $2,500 $2,500 Welland mitigation on site for addition of water to 2 acres In surface area $20.000 $50,000 =25,000 $2.132 $500 50 520,832 Initial IN of potable water (2009 potable water rate - ranges from 2 to 2.3 acres in surface area). $6,500 $15,500 521,722 $12.043 3 Na rVa 512,043 Retro-itt Irrigation $5,000 $10,000 $4,282 $4,089 $0 $0 $4,089 Groundwater well permit $900 $900 m $0 $900 Flow meter/data collector for outlet $1,107 $o $702 SD $702 fees Legal Subtotal $0 so so so s0 $0 Annual or on couts Standard txO---r)d permit for addltion of water 3 years) $5,000 $8,000 $2,315 $2,31 $0 $2,315 $2,315 MINDI/discharoe permit $1,000 $1.000 m 4 $0 SO gp Additional potable water (2009 rate - ranges from 2 to 2.3 acres in surface area - may be more $3 000 $3,500 If water loss Is higher than estimated). For 2010, a monthly water addition Is expected. $1.0.661 $0 50 - P acted 2010 and 2011 Potable water additions based on 2009 rates 532.30e $32,3w $64.772 Do-chlorination materials $4.000 $8,000 $4.988 $11.612 $3,245 $3,000 $17,757 Adaptive rnenagerrrant practices- subtotal of items fisted below $11,000 $",Soo Contract to add mlcr bas (Ottertail contract) $4,000 $5,OD0 $3.653 $3,852 6 $3 531900 $10,852 Duckweed removal (Ottertail corth`act) $1,000 $5,000 $1.839 Slte9 a $1.000 $1.000 $2.669 Water quality sampling (dty staff) $1,000 $2.500 $3,115 $3,115 $5.540 $5,340 $13,795` Solar See 0 solar panel replacements (city staff) $1,000 $1.50 $1,000 $0 $o $0 SO If appropriate. Installation of water aerator (electrical; solar is $8.900 more) $4,425 $0 S5.W $0 $5,848 Tree thinning (city staff) $500 $1,000 SSW $o so so 50 tie-application for simple wetland permit for view corridors (every 3 years) $1,500 $3,000 $0 3o S2.5D0 $2.500 Maintenance of the file drain $2,000 $4,500 $4,500 $0 $0 $0 $0 AnnualVOn-going Subtotal $24,000 $43.000 Staff O/M estimate. For 2009 - 2011, see Note 7 below. $25,000 $301000 $18,571 $13,4777 $7,000 $7,000 $27,477 AnnuallOn In Subtotal with Staff O/M $49 040 $73,000 Total Initial Coati for. PoldMG) Vatar,optlow- multiple fills per y"Wi 559'000 $058;000 $133,794 $Mo. 2 $82,421 j'. "'~,Sf,8b1 $213;084 Nobs, 1 Initial equipment costs to LAtze hydrant idling. (Coordinated with PW In 2009 for 2 days). 2 Education and outreach is being delayed due to budget oonWaints. Will occur as opportunities allow (Intsrpreeve signing, site education, volunteering. etc_) 3 2009 Water Block Rate Structure for over-budgeted wafer allocations. No stalling costs included. Initial fRl only. z 4 In 2009, CDPHE adopted a Low Risk Dlacharge Policy that will serve as the policy that ibis project will fall under. No statWdty permit necessary. 5 2000 Water Block Rale Structure for over-budgeted water allocations. No staffing costs Included. This asdrnate Is for Aug. - Oct. 2009. 6 Conn will cover microbe addtion and duckweed removal along with related site monitoring. M 7 Level of staffing time reduced due to buget and staffing constraints. Includes field activities, irigationdWorant supervW n, general mottoring. M 1