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10.15.2018 WRAB Packet - Agenda 5 Instream Flow ProgramC I T Y OF B O U L D E R WATER RESOURCES ADVISORY BOARD AGENDA ITEM MEETING DATE: October 15, 2018 AGENDA TITLE: Information Item – City of Boulder Instream Flow Program PRESENTERS: Jeff Arthur, Director of Public Works for Utilities Joe Taddeucci, Water Resources Manager Joanna Bloom, Water Resources Project Manager EXECUTIVE SUMMARY “Instream Flows” are water rights protected by the State to ensure water is left in Colorado’s creeks and rivers for environmental benefit. Boulder has supported a successful instream flow program on Boulder and North Boulder Creeks since 1990, and has been in the process of identifying ways to establish a South Boulder Creek instream flow program since the 1970’s. Streamflows and river health are growing areas of public interest, therefore the purpose of this item is to summarize the instream flow program and provide WRAB members an opportunity to ask questions or request additional information. BACKGROUND Boulder Creek – In the late 1800’s, water diversions from creeks and rivers supported Colorado’s settlement. Starting as early as 1859, irrigation ditches delivered water throughout Boulder Valley for residential use, hydropower generation and agriculture. Prior to 1972, Colorado water rights only covered stream diversions for use elsewhere. In the case of Boulder Creek, these water diversions routinely dried up the stream in late summer. In 1973, Colorado established a statewide instream flow program that created a new form of environmental water right. This program exclusively designates the State as the owner of instream flow water rights to maintain minimum environmental stream flows. Boulder Creek was one of the first beneficiaries of a year-round instream flow right. On paper, the right was for 15 cfs year- round, but other more senior water rights had priority during low flows, so the desired enhancements did not occur when needed most. To complement the State’s junior right, Boulder donated some of its most senior water rights, which provided more reliable year-round Boulder- and North-Boulder-Creek flows between 1.5 cfs and 15 cfs. The donated rights, which were valued at $12 million, may still be used in Boulder’s municipal system when not needed for instream flow and in drought years when Boulder implements water restrictions. Boulder Creek typically experiences high flows in spring and low flows in mid-to-late summer as runoff ends and irrigation use continues. During late summer, Boulder’s donated rights generally result in five to 15 cfs available to Boulder Creek through September, although flows briefly drop below five cfs in late summer most years. Beginning October 1, most of the donated irrigation rights go “out of season” and can no longer be used for instream flow protection. Throughout the winter, Boulder either bypasses water that would otherwise go to municipal use or makes 10/15/2018 WRAB Agenda 5 - Instream Flow Program Page 1 reservoir releases to maintain a minimum of 1.5 cfs in Boulder Creek until the donated irrigation rights can be used again. Although not as heavily impacted by diversions, the upper reaches of North Boulder Creek also benefit from State instream flow protection and Boulder’s storage releases and bypassed flows. City staff operates the Boulder Creek Instream Flow Program on behalf of the State as a condition of the donation agreement between the city and the State. Day-to-day operation of the instream flow program entails monitoring streamflow and coordinating with State water administration officials to ensure the legally protectable amount of water stays in Boulder and North Boulder Creeks. City staff also prepares an annual report detailing how the donated rights were used over the course of the year. South Boulder Creek - Land use and water diversions have also heavily impacted South Boulder Creek streamflows. The State has a 1980-era instream flow right that is junior to most other South Boulder Creek rights and therefore has limited ability to protect the creek in late summer and throughout winter. Boulder has looked for ways to improve South Boulder Creek streamflows since 1970’s, and the need for such a program has been identified as a priority in several City Council-accepted planning documents, including OSMP’s 1998 South Boulder Creek Area Management Plan and the 2010 Grassland Ecosystem Management Plan, as well as in Public Works’ 2009 Source Water Master Plan. To reliably address low flows on a regulated stream such as South Boulder Creek, reservoir storage space and water rights are needed so that releases can be made when streamflows fall below levels critical for healthy aquatic habitat. In 2010, Boulder City Council authorized Boulder’s participation in two agreements between Denver Water, Boulder, and Lafayette, detailing the implementation of the Gross Environmental Pool (GEP). Upon construction of the Gross Reservoir enlargement by Denver Water, the GEP will operate as a permanent, 5,000-acre- foot storage unit that will contain water supplied by Boulder and Lafayette and delivered to enhance stream flows in South Boulder Creek downstream from Gross Reservoir. Boulder’s releases from the GEP will be recaptured in a to-be-reconstructed Wittemyer Ponds for reuse by Boulder. ANALYSIS Boulder Creek - The Boulder Creek instream flow program successfully protects the aquatic environment and has resulted in significant improvements to Boulder Creek and North Boulder Creek streamflows year-round. The donated rights reliably provide streamflows in all but the most extreme years, such as 2002. During the 2018 irrigation season, the donated rights sustained Boulder Creek flows at rates between 4 and 15 cfs despite streamflows dropping earlier than average (see Figure 1). Winter North Boulder streamflows can be difficult to measure and can fluctuate with icing but are relatively steady and predictable. Likewise, early season irrigation ditch diversions can lower Boulder Creek winter stream flow levels through town; however, operational experience indicates that the program effectively maintains stream health. 10/15/2018 WRAB Agenda 5 - Instream Flow Program Page 2 South Boulder Creek - Boulder has applied for junior water storage rights in Gross Reservoir and Wittemyer Ponds and is evaluating other water rights for potential South Boulder Creek instream flow use. The goal is to use east slope water that will not result in “buy and dry1” or take away from other city programs. The terms of the GEP IGA’s may result in the City of Lafayette’s water rights portfolio filling the majority or all of the GEP in most years. If this is the case, Boulder’s GEP obligations will be significantly reduced. Regardless of what water is used, targeted flows will range between seven to ten cubic feet per second in the summer and five to seven cubic feet per second in the winter (see Table 1) and will be a significant increase over current flows that are limited due to water availability. Redeveloping Wittemyer Ponds plays a part in supporting a South Boulder Creek instream flow program and preserving municipal use of Boulder’s GEP water through an exchange. An exchange allows a water user to take water upstream and replace it in a different location downstream provided all other water rights in between are satisfied. The Wittemyer Ponds storage space will be a point of downstream storage and release for both GEP and municipal water rights exchanges (see Figure 2). Recapturing water in Wittemyer Ponds after its first use for instream flow or municipal purposes allows Boulder to achieve multiple uses of water, maximize the full range of its water rights and fulfill its GEP storage obligations. Denver Water is currently awaiting final permitting approval for Gross Reservoir enlargement and is facing legal challenges from local environmental groups who question the need for the project. To-date Boulder County and Denver Water have not agreed on whether the project is subject to the County’s Location and Extent Areas and Activities of State Interest (1041) review. It is unclear how these interests may impact the project moving forward. If Gross Reservoir enlargement is unsuccessful, Boulder will continue to explore other avenues to improve South Boulder Creek streamflows. NEXT STEPS Upcoming opportunities to improve Boulder Creek and Middle Boulder Creek instream flow programming include 1) collaborating with local ditch companies to install automated gates on the diversion structure at Broadway to respond more quickly to changes in flow; 2) identifying opportunities to enhance Boulder Creek winter flows during particularly cold low flow periods when icing can pose a threat; and, 3) formalizing a Middle Boulder Creek instream flow program, which currently successfully operates informally due to no competing stream diversions. Next Steps in establishing a South Boulder Creek instream flow program and improving aquatic habitat include 1) Establishing flow measurement at five locations identified in the 2010 IGA; 2) Modifying diversion structures to allow for instream flow bypass; and, 3) Completing two miles of stream channel restoration through OSMP lands aimed at providing winter aquatic habitat. ATTACHMENTS A - Figure 1 – 2018 Streamflow in Boulder Creek at Broadway B - Table 1 – Targeted flows for South Boulder Creek by segment and by season C – Figure 2 – Gross Reservoir and Wittemyer Ponds area map 1 “Buy and Dry” refers to agricultural land permanently taken out of irrigated production so associated water rights can be used elsewhere. 10/15/2018 WRAB Agenda 5 - Instream Flow Program Page 3 Attachment A 0.00 10.00 20.00 30.00 40.00 50.00 60.00 1-Jul 31-Jul 30-Aug 29-SepFlow in cfsStreamflow in Boulder Creek at Broadway Dry Year (2002) 2018 Average (2002-2012; 2014-2017) Approx. Protectable Amount (5 cfs) 10/15/2018 WRAB Agenda 5 - Instream Flow Program Page 4 Attachment B Table 1 - Targeted flows for South Boulder Creek by segment and by season Adapted from Boulder & Lafayette Intergovernmental Agreement dated Feb. 17, 2010 SUMMER SEASON (May- Sept) WINTER SEASON (Oct – Apr) STREAM SEGMENT Average year flow Dry year flow Average year flow Dry year flow Gross Reservoir to South Boulder Road (“Upper Segment”) 10 cfs 7 cfs 7 cfs 5 cfs South Boulder Road to confluence with Boulder Creek (“Lower Segment”) 4 cfs 2 cfs 2.5 cfs 1.5 cfs 10/15/2018 WRAB Agenda 5 - Instream Flow Program Page 5 Attachment C 10/15/2018 WRAB Agenda 5 - Instream Flow Program Page 6