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HomeMy WebLinkAbout6 - Information Item, Status Report on South Boulder Creek Instream FlowWATER RESOURCES ADVISORY BOARD INFORMATION ITEM To: Water Resources Advisory Board From: Ned Williams, Public Works Director for Utilities Carol Ellinghouse, Water Resources Coordinator Date: November 20, 2006 RE: Information Item: Status Report on South Boulder Creek Instream Flow EXECUTIVE SUMMARY Boulder Flycasters (the local chapter of Trout Unlimited) has requested the city's assistance in pursuing alternatives for enhancing instream flows on South Boulder Creek. Several altematives exist, with the most promising altematives using Valmont Reservoir, Wittemyer Ponds, or Baseline Reservoir to provide a source of exchange water to place in the Environmental Pool in Gross Reservoir. The Environmental Pool was developed through an agreement between the city of Boulder and Denver Water in 1998 to store water during late summer to provide winter instream flows in South Boulder Creek. (See Attachment A for map.) The following three alternatives are sufficiently viable to pursue their development: Valmont Reservoir is owned by Xcel Energy. Discussions are continuing with Xcel on the possibility of providing a substitute water supply for Valmont so that Xcel water rights can be stored in the Environmental Pool. An opportunity to deliver Colorado-Big Thompson Project (CBT) water into Valmont Reservoir has recently opened up with plans for construction of a raw water pipeline by the Town of Erie. Erie has been contacted about a possible cooperative effort. Wittemyer Ponds is a gravel pit complex on lower Boulder Creek owned by the city of Boulder through its Water Utility Fund. It was purchased for the purpose of storing fully- consumable effluent from the city's use of its municipal water. The ponds must first be sealed [o isolate them from the alluvial groundwater. Reusable water stored in [he sealed gravei pits could be exchanged for water to store in the Environmental Pool. Sealing the ponds will cost about $1.1 million and, depending on depth to bedrock, will provide about 1,300 acre-feet of storage space. • Water stored in Baseline Reservoir could be released from Baseline back into South Boulder Creek to both provide instream flow below South Boulder Road and as a source of exchange water for the Environmental Pool in Gross Reservoir. Facilities to return water from Baseline Reservoir to the creek do not presently exist. A pipeline to serve this function could be constructed, but might cost about $500,000 since it must pass under Cherryvale Road and through Open Space land. It may be possible to set up a temporary pipeline and pumping alternative that made use of an existing culvert under the road at a cost in the range of $50,000 or less, but with higher operation costs. Page 1 L.ess promising alternatives focus on Barker Reservoir to supplement South Boulder Creek flows. The Barker Reservoir alternatives would involve altering a dam under Federal Energy Regulatory Commission (FERC) jurisdiction, constructing a pipeline on a mountainous route, either diminishing Middle Boulder Creek instream flows or increasing the city's vulnerability to drought, and reducing hydropower production. BACKGROUND The development of an instream flow program for South Boulder Creek began in 1980 with a filing by the Colorado Water Conservation Board (CWCB) far instream flow rights. The Water Court issued a decree in 1983 that adjudicated a water right with priority date of December 2, 1980 for instream flows in South Boulder Creek in the amount of 15 cubic feet per second (cfs) from Gross Reservoir to South Boulder Road for the period from May 1 through September 30 of each year. The amount that was decreed for the winter period from October 1 to Apri] 30 of each year varied by reach and is 6 cfs from Gross Reservoir to Eldorado Springs and 2 cfs from Eldorado Springs to South Boulder Road. The CWCB did not seek a decree for South Boulder Creek from South Boulder Road to the Boulder Creek confluence because of a requirement that CWCB filings be ]imited to actual water available for instream flow purposes. There is very litde water available for instream flow protection below the diversion points far Baseline Reservoir. Under the CWCB decree, protection of instream flows at the decreed levels is subject to all "uses or exchanges of water being made by other water users pursuant to appropriation or practices in existence on December 2, 1980." Given the seniority of most water rights on South Boulder Creek and the over-appropriated status of the stream, the effect of the CWCB right was mostly to prevent instream flow levels from being further depleted. In 1992, Boulder Flycasters developed a plan for habitat improvements on South Boulder Creek. They have warked steadily since that time, in conjunction with City's Open Space and Mountain Parks Department and several ditch companies, to construct structural improvements to the stream channel and to seal leaky headgate structures that drained water out of the creek in the winter. City staff continued efforts to develop instream flows on South Boulder Creek during the 1990's. Because there are so many diverters other than the city's on South Boulder Creek, instream flow . development will take cooperative efforts among many parties and can not proceed based on relatively independent efforts by the city as it has on North Boulder and Middle Boulder Creeks. On South Boulder Creek, the major storage reservoirs, which are needed to supply a winter instream flow, are not operated by the city of Boulder. City staff approached Denver Water in 1992 with a proposal to use Gross Reservoir storage space for purposes of providing South Boulder Creek instream flows. In 1994 and 1995, Denver Water participated in joint studies with the city and Public Service Company of Colorado (now Xcel) to investigate the feasibility of an integrated instream flow program for Middle Boulder Creek below Barker Reservoir and South Boulder Creek below Gross Reservoir. Discussions have continued with Xce] on possible use of Valmont Reservoir and its water rights in an instream flow program for South Boulder Creek in ways that might also enhance Xcel's cooling water needs at Valmon[. In 1996, discussions resumed with Denver Water as they entered into a FERC licensing process for Gross Reservoir. These discussions resulted in an agreement in 1998 to progress toward Page 2 meeting South Boulder Creek instream flow needs through the creation of the Environmental Pool in Gross Reservoir. The Environmental Pool consists of 2,500 acre-feet of water starage space for purposes of providing winter instream flows for South Boulder Creek. The water to be stored has not yet been identified and would need to be provided by Boulder or interested parties such as other surrounding cities, Boulder Flycasters or Xcel. City staff inet with Boulder Flycasters in November 2002 and conferred on plans for further discussions that included other parties interested in South Boulder Creek. In August 2004, Boulder Flycasters issued a study of instream flow opportunities done by Hydrosphere that buil[ on previous work that the city had commissioned from Hydrosphere in 1994. In October 2004, Boulder Flycasters held a South Boulder Creek Symposium with representatives of area cities, Xcel, Denver Water and the State Engineers' Office. The Symposium provided a forum for the parties to discuss the many water trades, exchanges, storage options and water management possibilities that had been conceived over the years for providing winter instream flows in South Boulder Creek. In August 2006, Boulder Flycasters met with the WRAB to provide information on instream flow efforts and to explore interest in fuRhering efforts on South Boulder Creek. ANALYSIS Instream Flow Amounts Needed Flow amounts decreed in the CWCB filing were based on a requirement that any CWCB filing be limited to actual water available for instream flow purposes. Field studies done in the late 1970's by the Colorado Division of Wildlife (DOW) using the R2-Cross method defined South Boulder Creek's physical capacity to provide habitat far fish at given flow levels. The 15 cfs summer level represents a desired low flow condition and the 2 cfs winter level is considered an absolute minimum level for fish survival. Based on the habitat studies, a more desirable winter level for South Boulder Creek, if water could be made available, would be 7 cfs from Gross Reservoir to South Boulder Road and 2.5 cfs from South Boulder Road to the confluence with Boulder Creek. During the winter, the city of Lafayette had historically diverted about 3 cfs of water out of South Boulder Creek at the headgate to the Lafayette Pipeline near Eldorado Canyon. This water was carried to Lafayette's Marshall Water Treatment Plant. About 5 years ago, Lafayette permanently closed the Marshall plant rather than invest in extensive upgrades. Water that had previously been diverted out of South Boulder Creek at Eldorado Canyon in the winter now remains in the creek down to the diversion point into Baseline Reservoir near South Boulder Road. If Lafayette continues this operational mode for its water system as is expected, then the winter instream flow level is at a minimum of 3 cfs and would require an additiona] 4 cfs to bring it up to the desired level of 7 cfs. This equates to about 1,400 acre-feet of water over the six-month winter period. Availabilitv of Gross Reservoir Environmental Pool In most years, Denver Water completely fills Gross Reservoir with spring runoff From the Westem Slope, delivered through Moffat Tunnel. Space in the Environmental Pool is created as Denver Water draws water out for municipal use following the spring fill. The agreement for Gross Reservoir use for instream flow purposes provides that, as soon as reservoir space becomes availabie after May 1 of each year due to Denver Water withdrawals, Boulder can store up to 2,500 acre feet of water in Gross Reservoir on a space-available basis. Space usually starts Page 3 becoming available in mid-July. Between November 1 and April 30, Boulder can call for releases of this water from the reservoir to create flows of up to 7 cfs in South Boulder Creek between Eldorado Springs and the confluence with Boulder Creek. Any water remaining in the Environmental Pool on the next May I becomes available for Denver Water to use for its municipal needs. Under the agreement, once Denver Water resolves water delivery problems within its northern water distribution azea caused by water starage limitations, the full 2,500 acre- feet capacity of the Environmental Pool will be available beginning on July 15 of each year based on increases of 42 acre-feet per day in storage space. Efforts by Boulder to place wa[er in the Environmental Pool can be enhanced by others interested in providing water for instream flow. By entering into the agreement with Denver Water, Boulder secured access to storage capacity on South Boulder Creek necessary to meet the instream flow needs of South Boulder Creek. This agreement is an important part of solving the winter instream flow deficit, but additional actions are needed before enhanced flows are seen in the creek. Boulder and/or others need to secure water rights for the Environmental Pool. There are a range of alternatives for water to place in the Environmental Pool including commitment of water rights now owned or acquired by either city's Open Space and Mountain Parks DepaRment or the Water Utility Fund, dedication of water rights acquired by others, Water Court proceedings to add new storage locations and/or instream flow use for existing water rights (possibly including rights owned by others with their agreement), and other agreements for water management alternatives. Costs for each altemative have not been fully developed. Variations of many of the alternatives include use of Valmont Reservoir, Baseline Reservoir, Wittemyer Ponds, CBT water, Windy Gap water, and/or Boulder Creek instream flow program residual water. Possible Use of Erie Pipeline and Valmont Reservoir One altemative could make use of water rights owned by Xcel for purposes of maintaining cooling water levels at the Valmont Power Plant. If a reliable substitute water supply can be provided for Valmont Reservoir, the senior water rights for the reservoir could be changed in Water Court to allow an alternate point of storage in Gross Reservoir. There is no agreement presenUy in place with Xcel for a water substitution of this nature. One means to provide Xcel with a reliable substitute supply would involve a joint effort with the Town of Erie. Erie is in the process of constructing a raw water pipeline beginning at the Boulder Supply Canal which carries water from Boulder Reservoir to Boulder Creek. The pipeline will run from about 75`h Street and Jay Road to Erie and will deliver the Town's CBT and Windy Gap water to its treatment plant The pipeline route will run close enough to Valmont Reservoir that a tap could be placed on the pipeline to feed a branch of the pipeline dischazging into Valmont Reservoir. This would allow CBT water to be made directly available to Xcel to substitute for use of its water rights to fill the Environmental Pool. The CBT could be leased water that is excess to Boulder's municipa] supply in any year or [hat is obtained from other sources. (Any water leased for this use by the city would decrease the amount of CBT water leased to agricultural users that year.) City staff is pursuing discussions with Erie on this possibility. Use of Wittemver Ponds Wittemyer Ponds is a gravel pit complex owned by the city through the Water Utility Fund and is located north of Boulder Creek at Highway 52 and County Line Road. The city acquired these Page 4 ponds in the late 1980's for the purpose of developing a site to store fully-consumable effluent from the city's future use of its Windy Gap water as a source of water to exchange back into Barker Reservoir. Most of the commercial gravel deposits have been mined out, leaving about 1,300 acre-feet of potential reservoir storage space if the reservoir site is re-graded and bedrock is 20 feet down. The gravel pits are presently connected with the alluvial groundwater table in the area and would need to be sealed to isolate the reservoir storage space from the alluvium before the ponds could be used for storage of reusable water. The estimated cost of placing a full curtain wall using bentonite slurry around Wittemyer Ponds, assuming 20 fee[ depth to bedrock, is about $11 million. This money is not budgeted in the Water Utility Capital Improvement Plan (CIP). The city holds title to the Wittemyer Ponds property and has granted Boulder County a conservation easement. It will likely require a Boulder County review process for the sealing project. A condition of the conservation easement is that the easement will revert to the city if the county does not give approvals that allow the city to develop the property as a water storage complex. The city could then sell the property for development. If the ponds were sealed and filled with reusable water, such as Windy Gap effluent, they could become a source for water to be exchanged into the Gross Reservoir Environmental Pool in addition to the expected uses of exchange into Barker Reservoir for additional municipal water or Iease to agricultural users. If water is released from the Environmental Pool for winter instream flow use on South Boulder Creek, a portion of the water could be recaptured in Wittemyer Ponds for re-exchanging into the Environmental Pool the following year. Wittemyer Ponds could also be used to capture residual water from the Boulder Creek instream flow program that is owned by the city and could be exchanged to Gross Reservoir. Exchanges of water can take place when there is enough water in the stream between the "exchange-from" point and the "exchange-to" point to satisfy diverters that are in priority. An analysis completed by Hydrosphere in 1999 showed that water could be exchanged to Gross Reservoir in July and August of most years. Outside of this window, the usefulness of the exchange is limited because space would not often be available in the Environmental Pool until July and exchange potential drops dramatically by September in most years. Even so, it appeazs that from 900 to 2,500 acre-feet could be exchanged to Gross Reservoir in twathirds of the years. Return oF Water from Baseline Reservoir to South Boulder Creek Water is stored in Baseline Reservoir from South Boulder Creek and from Boulder Creek via the Anderson and Anderson Extension Ditches. The city's Water Utility Fund owns 13 percent of the shares in the Base Line Land and Reservoir Company which owns Baseline Reservoir. In years that this water is not needed for exchanging water into Barker Reservoir for municipal use and is not leased out for agricultural use, it might be a source both for maintaining instream flow below South Boulder Road and for exchange into the Environmental Pool. As an additional benefit, it could also be a substitute water supply for Viele Lake so that water stored out of priority could be kept in the lake. Baseline Reservoir sits east of Cherryvale Road and north of South Boulder Road and is only a short distance from South Boulder Creek on the other side of a small ridge. A pipeline could be constructed from Baseline Reservoir under Cherryvale Road to South Boulder Creek that, if laid deep enough, could carry water back to the creek by gravity. This would require capital Page 5 investment in the pipeline, broadly estimated to be in the range of $SOQ000, which is not included in the Utility CIP. It would also require construction of a pipeline across Open Space land laying to the west of Cherryvale Road. An alternative would be to lay a pipeline of a more temporary nature by threading inexpensive polyvinyl-chloride (PVC) pipe through an existing drainage culvert under Cherryvale Road and across the surface of the Open Space land to a drainage leading to South Boulder Creek. The temporary pipeline would require a pump to draw water out of Baseline Reservoir because it would be at a shallow grade. This option might be accomplished far less than $50,000 in capital expenditures, but would require more time and effort to operate. The on-going operating costs would be greater than with a permanent pipeline. Both of these alternatives would require agreements with Base Line Company and Boulder County. Approval from the Open Space Board and/or City Council could be needed for a pipeline crossing Open Space land. ~ Dse of Barker Svstem to Move Middle Boulder Creek Water to South Boulder Creek An alternative has been proposed that would take water from Barker Reservoir and carry it in the Barker Gravity Pipeline to Kossler Reservoir which sits on the ridgeline between Middle Boulder Creek and South Boulder Creek basins. Then, instead of running the water through the pipelines running to Betasso Water Treatment Plant, it would be released through a new outlet constructed in Kossler Reservoir to Woods Gulch on the South Boulder Creek side of the reservoir. This altemative is not as attractive as others for several reasons. Woods Gulch is a small, steep stream channel with intermittent flows that crosses public and private land. If water were to be released mto Woods Gulch at a high enough flowrate that it would reach South Boulder Creek, it would likely cause some flooding and environmental damage to the stream channel. Therefore, this alternative would likely require the construction of a pipeline from Kossler Reservoir to South Boulder Creek (possibly costing $1,000,000) along with the need to obtain a Special Use Pernvt from the US Forest Service for the pipeline route. In addition, approval from FERC, issuer of the license for the Barker system, would be required to alter the dam at Kossler Reservoir for installation of a new outlet. The water to be diverted from Middle Boulder Creek to South Boulder Creek must be attributed to a particular water right. The water would be taken out of its historic basin, so it would be considered a consumptive use for the originating basin for purposes of protecting other water rights owners from injury due to lost water yield. In order to have any consistent yield, one of the city's municipal water rights would have to be changed through Water Court to allow instream flows in a different basin than the originating basin for the water. This type of change would be expensive (estimated at $100,000 or more) and would open the city's water rights to the possibility of new decree limitations on municipal use. This instream flow alternative would reduce the city's municipal water rights yields, increase vulnerability to drought, decrease the city's ability to commit water for instream flows in Middle, North and Main Boulder Creeks, increase treatment costs for substituting municipal supplies at Boulder Reservoir, and would reduce hydropower production that cuttently takes place with Barker system water deliveries. Page 6 CONCLUSION Although there are several options for enhancing streamflow levels in South Boulder Creek, the most promising alternatives will require some leve] of capital expenditure by the city, most likely to come from Open Space and Mountain Parks Department or the Water Utility Fund. At this time, no money has been budgeted for this purpose. City staff will continue following up on viable alternatives for South Boulder Creek instream flow and on developing agreements with parties in a position to help. Staff would welcome recommendations from the WRAB on actions to pursue and on budget alterations that should be considered. Page 7 H~ L nd. 1, Lafayette Pipeline 10. McGinn DMCh 2 CommuniryDitch 11. HowakDitch 3. ~av~dsan Di~ch 7& EeatBOUIEer~RCh 4 GootlhoaDitch ia. vaimominieudonesaoonneiry 5 SouNBoultlerBearCreek~itch 6 Ory Lreek 1F2 Oittl~ ] Marsnallville ~~ch 8 Shearcr0itch 8 South BaulderCarryon Dktli Be4seoVYTP From,Nokh Boulder Creek Wahrshetl ~ Bouldsr Creak ~ From Barker ReServoll ` Grow Reservoir KosalerLake I ) WoodGUlch Ponds ~ pt ~ L~_~ ~ ~~~ GooaeHavenPOntls i ~ n ~ r^ N VdlfllOtlf RBSBrvOIf V ~ ~ 2 ^ ~ryCreek s ~ F ~ Iatiro~eGOl ~g m Course " Baseline Res ir Basaline WTP Weliman Canal ~p / BaselineRoad ~ A~Merso n Ditch 11 Wanaka Reservoir / S.BoulderROad 'O Gootlhue Diteh B9 ~ ~ ~ /~ ~ soutn eo~ma. creo~~~ a ~ Z Communlty DHch H YUR~ERE Cowdrey Gulch ~ Leqend - Creak or ~itch Marshall Rasarvoir - Road ' -- Pipeline \ ~ WaterT~atrnentPlant • Drversion Heatlgate 0 1 2 N Diversian Canal ~ W~ E miles g General Location Map ATTACHMENT A