Colorado River Storage Project
Fontenelle Working Group
April 27, 2010
This meeting was held at Seedskadee National Wildlife Refuge on the Green River below Fontenelle Dam. Beverley Heffernan, of Reclamation’s Provo office, led the meeting. Meeting participants are listed at the bottom of the page.
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.
The hydrology presentation began with reservoir and basin current conditions. Fontenelle Reservoir is 36% full (125,000 acre-ft), which is typical for this time of year. The reservoir elevation is 6471 feet above sea level or 35 feet from top of pool. Inflow has been increasing and the five-day average is 1700 cfs. 800 cfs is the current release. Basin snow water equivalent (SWE) conditions are currently 51 percent of average, significantly below the conditions this time last year. The basin is classified as being in moderate to severe drought according to the US Drought Monitor. The temperature and precipitation outlook for the next thirty days is slightly above normal precipitation and equal chances for above or below normal temperatures.
The April 1st most probable water supply forecast for the April to July spring runoff season is 360,000 acre-feet, or 42% of the historic average. The minimum probable (90% exceedence) is 205,000 acre-feet and the maximum probable (10% exceedence) is 560,000 acre-feet. Note that there is an 80% chance that reservoir inflows will be between the minimum probable and maximum probable forecast values. There is a 10% chance inflows could be below 205,000 acre-feet and a 10% chance inflows could be above 560,000 acre-feet. The most probable forecast was updated mid-April to 430,000 acre-feet, or 50 percent of average. This reflects the storms experienced in the first few weeks of April. The historical average for the 1971-2000 period is 858,000 acre-feet and for the 1976-2005 period is 759,000 acre-feet. Given this forecast, Fontenelle is expected to receive less inflow this year than in the past two years.
Given the April 1st forecast, the reservoir was expected to come approximately 10 feet short of filling this year. The slight improvement in the forecast issued mid-April makes a significant difference in projected elevations; if the improved conditions hold, the reservoir will likely fill by August. June is expected to be the peak inflow month. Last year the peak release was 8,030 cfs for 21 days. This year releases will likely remain at or near 800 cfs for the entire summer. These projected releases are highly provisional and subject to change based on changing basin and reservoir conditions. The maximum probable peak release (10% exceedence) is 3,050 cfs for a month and the minimum probable (90% exceedence) release is 700 cfs for the summer. Any increase in releases would likely occur in July, once it is clear that there is enough water to increase releases. Any decreases would likely occur in late May or June, depending on how the forecast trends.
Questions and general discussion followed the hydrology presentation.
Mike Meyer of the Jim Bridger Power Plant expressed concern about the dry basin conditions and the risk of river flows potentially falling below adequate levels for the pump station intake. It is estimated that a release of approximately 400 cfs is required to maintain enough head for the power plant intake to divert its 50cfs. Mike questioned whether it would be prudent to proactively decrease releases, say in the next month, to decrease the risk of later not having enough water. Katrina explained that because releases are already at the relatively low 800cfs, the likelihood is very low that releases would later have to be decreased to near 400cfs. This is particularly true because basin conditions are trending wetter, rather than drier and the minimum probable inflow forecast indicated that releases could be maintained at 700cfs for the entire summer, fall and winter seasons. Katrina committed to evaluating the May 1st reasonable minimum inflow forecast. If the May 1st minimum probable indicates that releases would need to be reduced to 500 cfs, Katrina said that Reclamation would consider decreasing releases proactively to mitigate the risk. NOTE: Since the meeting, the May 1st minimum probable forecast has been issued. The minimum probable forecast increased from 205 KAF to 260 KAF and modeling projections indicate that with this improvement releases can be maintained at well above 500cfs for the entire summer and following winter.
Bryan Seppie of the Joint Powers Water Board discussed that sudden increases in river flows (either from increased reservoir releases or from side inflows below the dam) are bad for water quality. Sudden increases in river flow stir up sediment and potentially wash streamside pollutants into the river. The water treatment plant adjusts by using more chemicals and in some instances has to shut down completely until the pulse of sediment and pollutants pass. Sudden increases in river flows are particularly more difficult to manage when the average flow is lower and there is less water in the river to absorb and dilute the pollutants entering the system. Bryan mentioned that there has been good coordination and communication in the past between Reclamation and the water treatment plant, but wanted to reiterate the importance of this communication, particularly in this dry year. Katrina said that she would be sure to coordinate and communicate with the treatment plant if increases occur this year.
Bill Reed of the Colorado Basin River Forecast Center (CBRFC) presented on the Upper Green River forecast, how it is developed, what looks like now, and what we can expect over the rest of the season. Bill described who the CBRFC is and how they have multiple forecasting tools to develop forecasts at multiple points on the river, of which Fontenelle Inflow is one. Forecasts are also coordinated with the Natural Resources Conservation Service (NRCS). Bill described the statistical models and ensemble streamflow prediction model and how these models capture 78% of what is going on in the basin (forecast vs. observed has an R2 of 0.78) but that 22% of the variability is not captured in the forecasting models. Snowpack is the primary driver for inflows and 90% of seasonal snowpack has accumulated by April 1st. Other drivers for the April to July inflow volume (when the bulk of the annual runoff comes) are observed precipitation, observed streamflow and modeled soil moisture conditions. Bill reported that observed headwater streamflow is significantly below average (less than 70% of average) and observed basin snow water equivalent is approximately 7 inches, or approximately 42% of the seasonal average. Upper Green modeled soil moisture states ranged from below average to near average heading into the winter. Observed cumulative seasonal precipitation was less than 50% of average for much of the basin. Bill explained how the April to July inflow volume forecast is first issued in January and is updated monthly through July. He also pointed out that the ensemble streamflow prediction model results are posted weekly to the CBRFC website and that the weekly updates are valuable to detect trends in the forecast (i.e., whether it’s getting wetter or drier.) In addition to the water supply forecasts, Bill mentioned that the CBRFC issues daily and hourly flow forecasts. Bill welcomed any questions.
Fontenelle Functional Exerciese- Tom Ryan:
Tom Ryan of Reclamation’s Hydropower Office spoke about Reclamation’s upcoming functional exercise for Fontenelle. The functional exercise will be an exercise for Reclamation to test Reclamation’s response in the event of an emergency at Fontenelle Dam. The exercise is planned for sometime this summer (2010). In the early months of 2010 Judy Valentine and the Sweetwater County Emergency Management team had started efforts to do a full-scale emergency response exercise for Fontenelle Dam and the surrounding area; however the exercise was cancelled in early April. Tom discussed that the functional exercise that Reclamation is planning is not a continuation of Sweetwater County’s original efforts. Reclamation’s functional exercise will not be a full-scale exercise and will not be as large-scale as that originally planned by Sweetwater County. Tom discussed that while this exercise is designed to evaluate Reclamation’s response, Reclamation welcomes and encourages the involvement of other agencies interested in participating. The exact details of the scenario to be tested in the exercise have not yet been decided. Reclamation still needs a location to conduct the functional exercise. Any parties interested in participating in the exercise should contact Tom Ryan at email@example.com.
Aquatic Invasive Species Program - Robb Keith:
Robb Keith of the Wyoming Game and Fish Department spoke about the Aquatic Invasive Species Program being implemented by the State. The program is aimed at preventing the spread of quagga and zebra mussels to Wyoming water bodies. To date no mussels have been reported in Wyoming waters, however there is great concern that boats previously in other reservoirs with the mussels (such as Lake Mead) could transport the mussels in their ballasts. The mussels are extremely damaging to water transportation infrastructure such as pumps, filters, pipes, canals, as well as recreation equipment such as boats. The cost from damage from the mussels is in the millions of dollars. They are a huge threat to dams and powerplants as well as the native ecosystem. The mussles have no natural predators in the West and there is no known method to effectively remove mussels from a water body once they take hold. The program received $1.5M in state funding and will be supplemented by a user decal system. Any watercraft 10ft or greater must get a decal. The program has hired seven technicians in the Green River Basin area. There will be inspection and decontamination stations at various reservoirs across Wyoming. However, it is recognized that the most effective means of preventing the spread of the species is education.
Stilling Basin Inspection: Bryan Seppie of the Joint Powers Water Board asked about the Fontenelle stilling basin inspection that took place last spring. Steve Hulet stated that the final report is being issued by Reclamation’s Technical Service Center in Denver and has not yet been completed. Steve reported that significant damage was found in the basin during the inspection. The question is what the full extent of the damage is, whether damage is continuing, and whether it is necessary to repair the existing damage and, if so, when do the repairs need to be done? Answers to these types of questions are expected to come out in the final report.
The workgroup’s next meeting is scheduled for Tuesday August 24, 2010 at 10am at the city of Green River City Hall.
Fontenelle Working Group Meeting Minutes:
|Katrina Grantz||Bureau of Reclamation|
|Beverley Heffernan||Bureau of Reclamation|
|Bill Reed||Colorado Basin River Forecast Center|
|Ashley Nielson||Colorado Basin River Forecast Center|
|Mike Meyer||Jim Bridger Power Plant|
|Dan Miller||Jim Bridger Power Plant|
|Eddy Boe||Wyoming State Engineer's Office|
|John Yarbrough||Wyoming State Engineer's Office|
|Robert Keith||Wyoming Game and Fish Department|
|Bobby Compton||Wyoming Game and Fish Department|
|Steve Hulet||Bureau of Reclamation|
|Erek Roosa||City of Green River Parks and Recreation|
|Ben Bracken||Joint Powers Water Board|
|Bryan Seppie||Joint Powers Water Board|
|Heather Patno||Bureau of Reclamatiom|
|Malcolm Wilson||Bureau of Reclamatiom|
|Carl Millegan||US Fish and WildlifeService|
|Kristine Blickenstaff||Bureau of Reclamation|
|Tom Ryan||Bureau of Reclamation|
|Kirk Jensen||Bureau of Relcamation|
|Steve Hulet||Bureau of Reclamation|
Email comments/inquires to: ResourceMgr@usbr.gov