Colorado River Storage Project
Fontenelle Working Group
August 24, 2010
This meeting was held at the Wyoming Game and Gish Dept and attended by fourteen participants. See below for a list of participants.
The purpose of working group meetings (held in April, and August) is to inform the public and other interested parties of Reclamation's current and future operational plans and to gather information from the public regarding specific resources associated with Fontenelle Reservoir. In addition, the meetings are used to coordinate activities and exchange information among agencies, water users, and other interested parties concerning the Green River.
Bill Reed of the Colorado Basin River Forecast Center (CBRFC) presented a review of the 2010 water supply forecast for Fontenelle Reservoir. Bill has been the forecaster for the Upper Green for several years now. Bill’s presentation covered how basin conditions changed throughout the season and how this affected his forecast. Snow accumulation was significantly below average this year with a seasonal peak of 58% of average. Cooler than average temperatures from the end of April through mid-May contributed to delayed snowmelt. By June 1st, all measured snow (below 9,400 feet) was gone. Bill noted that there are no SNOTEL stations above 9,400 feet; this lack of data makes it difficult to know how much water content remains at the high elevations. Unexpected above average precipitation occurred in April, May and June, improving overall basin conditions and raising the forecast. Bill described the evolution of the April to July (A-J) runoff season from its first issuance in January through the last issuance in July. Forecasts in January were approximately 25% above the final observed A-J inflow volume. In April the forecasts were approximately 25% below the final observed A-J inflow volume—at that time seasonal basin conditions were dry. Forecasts rose during the runoff period as above average precipitation was received in April, May, and June. The final observed April-July runoff volume into Fontenelle Reservoir was 487 kaf (57% of average). Bill noted that next year Ashley Nielson will be the primary forecaster on the Upper Green. Also, Bill mentioned while his office issues the water supply forecast, the local National Weather Forecast office in Riverton, WY is the primary forecasting office in the case of flash flooding and/or dam break situations. The Riverton office is responsible for issuing a flood watch or warning, as needed.
Some discussion focused on why there no SNOTEL stations at higher elevations and whether there were any plans for placement of stations at higher elevations. The SNOTEL network is maintained by the NRCS, however participants at the meeting discussed that it is likely an accessability issue in the Wind River Mountains that prevents placement at the higher elevations.
The hydrology presentation began with reservoir current conditions. Fontenelle Reservoir is 93% full (322,000 acre-ft). The reservoir elevation is 6503 feet above sea level or 3 feet from top of spillway. Inflow has been decreasing and the five-day average is 600 cfs. 1,100 cfs is the current release, however the plan is to ramp down to baseflows for fall and winter within the next week.
The runoff this spring was below average at 9488,000 acre-feet (57% of average). The basin snow water equivalent (SWE) conditions were significantly below average this year,peaking on April 14th at 65% of average. In the early spring releases were decreased from the winter release rate of 980 cfs to 800 cfs in response to reservoir inflow forecasts predicting inflows would be insufficient to fill Fontenelle Reservoir. Conditions improved throughout the spring and releases were increased in the end of June and early July once it was highly likely that the reservoir would fill. Bypass releases (above powerplant capacity) of up to a total release of 3,050 cfs were sustained for approximately 12 days, including ramping. In the late summer (late July) releases were lowered to 800 cfs for four days to accommodate work at the City of Green River’s Killdeer Wetlands project. The observed spring runoff was greater than was forecasted in April, however, it was below the max probable forecasted inflow. The above average inflows were primarily due to a very wet June. Releases this season were higher the most probable schedule presented in April, but lower than the reasonable maximum that was projected in April. Despite a pessimistic inital outlook in April, the reservoir did fill this season and is still mostly full.
Projected inflows for water year 2011 are below average (85% of average). This forecast is produced by the Colorado Basin River Forecasting Center's (CBRFC) Ensemble Streamflow Prediction (ESP) model which generates a spaghetti plot of potential inflow scenarios over the next water year. It was noted that forecasts generated in August have a high degree of uncertainty and essentially assume close to average inflows coupled with current basin conditions (soil moisture, etc.). Under the most probable and max probable inflow scenarios, Fontenelle Reservoir is expected to fill by August next year. Under the minimum probable inflow scenario, Fontenelle will only reach 6485 ft (approximately 21 feet below top of pool). Than range of potential releases next spring is 700 cfs (minimum probable scenario) to 7,500 cfs (maximum probable scenario). The wide range of potential inflows and releases is indicative of the uncertainty in the forecast at this point in the year. Releases for the fall and winter season are projected to be approximately 1,000 cfs however, this could be slightly adjusted in mid-November if basin conditions significant change.
Questions and general discussion followed the hydrology presentation.
Fontenelle Functional (Emergency Response) Exercise: Reclamation is currently in the late planning stages for a functional exercise at Fontenelle Dam. The functional exercise is an exercise to test Fontenelle’s emergency action plan and involves Reclamation and entities/agencies that would be involved in an emergency response (e.g., weather service, county and city emergency responders, fire department, utilities, etc.) An orientation seminar took place on August 19th at the Green River fire station and interested parties (many are also Fontenelle Work group members) were in attendance. The function exercise will take place at Seedskadee National Wildlife Refuge Visitors Center on September 14, 2010.
Fall Maintenance: The 2010 annual fall maintenance at Fontenelle dam and powerplant is scheduled for September 13th to October 31st. The power plant will be off-line for much of this maintenance, but the scheduled release will be maintained by releasing water through the bypass tubes.
Stilling Basin Inspection: In May 2009 the stilling basin at Fontenelle Dam was dewatered, cleaned and inspected. Bryan Seppie asked if a report on the findings of this inspection has been released. Steve Hulet said that Reclamation is still waiting for the final report on the results of the inspection before we can come to a decision on whether repairs are necessary and, if so, when that work would be accomplished. Steve noted if repairs are to occur, that work is likely several years out. Robb Keith of Wyoming Game and Fish noted that Reclamation and WGFD worked well together during the last dewatering to rescue stranded fish in the stilling basin and requested a similar coordination if dewatering is necessary again. Steve assured him Reclamation would work with WGFD again.
The workgroup’s next meeting is scheduled for Thursday April 21, 2010 at 10am at the visitor's center at Seedskadee National Wildlife Refuge below Fontenelle Dam.
Fontenelle Working Group Meeting Minutes:
|Katrina Grantz||Bureau of Reclamation|
|Bill Reed||Colorado Basin River Forecast Center|
|Mike Meyer||Jim Bridger Power Plant|
|Eddie Baker||Jim Bridger Power Plant|
|Eddy Boe||Wyoming State Engineer's Office|
|Robert Keith||Wyoming Game and Fish Department|
|Bobby Compton||Wyoming Game and Fish Department|
|Walt Bratton||City of Green River Parks and Recreation|
|Allan Wilson||City of Green River Parks and Recreation|
|Bryan Seppie||Joint Powers Water Board|
|Natalie Fath||US Fish and WildlifeService|
|Kristine Blickenstaff||Bureau of Reclamation|
|Kirk Jensen||Bureau of Relcamation|
|Steve Hulet||Bureau of Reclamation|
Email comments/inquires to: ResourceMgr@usbr.gov