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Fontenelle DamFontenelle Reservoir


Colorado River Storage Project

Fontenelle Working Group
Meeting Minutes
August 25, 2009

Participation

This meeting was held at the City of Green River city hall. Ed Vidmar led the meeting. Meeting participants are listed at the bottom of the page.

Purpose of Meeting

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.

Hydrology Presentation - Katrina Grantz

The hydrology presentation began with reservoir current conditions. Fontenelle Reservoir is 93% full (319,700 acre-ft). The reservoir elevation is 6503 feet above sea level or 3.3 feet from top of spillway. Inflow has been decreasing and the five-day average is 950 cfs. 1,600 cfs is the current release, however the plan is to ramp down to baseflows for fall and winter later in the week.

The runoff this spring was slightly above average at 968,000 acre-feet (113% of average). The basin snow water equivalent (SWE) conditions were about average this year, however it was noted that even though the snotel stations reported no snow near the end of June, significant snow still remained at the higher elevations. In the early spring releases were maintained at baseflows levels (950 cfs) until late May while maintenance work was being performed on the stilling basin at the dam. Bypass releases (above powerplant capacity) of up to a total release of 8,040 were sustained for over three weeks in June and July. In the late summer (late July) releases were lowered to 900 cfs for four days to accomdate work on the kayak park at the City of Green River. 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 than was originally anticipated due to the increased inflows. Releases, were, however, well below the 11,500 cfs safe channel capacity of the City of Green River. The reservoir filled earlier than ususal this year and is still mostly full.

Projected inflows for water year 2010 are slightly below average (94% 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 6491 ft (approximately 15 feet below top of pool). Than range of potential releases next spring is 900 cfs (minimum probable scenario) to 8,000 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 1,150 cfs with a max range of 1,000 cfs to 1,325, however, this will be adjusted to accomodate maintenance work at the dam mid September to late November (see discussion item below.)

Questions and general discussion followed the hydrology presentation.

General Discussion

Fall Maintenance: The 2009 annual fall maintenace at Fontenelle dam and powerplant is scheduled for October 5 to December 1. This year, the generator exciter will be replaced requiring a longer than usual maintenance period. The power plant will need to be shut down for approximately 10 weeks to complete the needed work. During this time water will need to be bypassed around the powerplant. Katrina Grantz of Reclamation explained how decreasing the releases from the dam slightly (from 1,220 cfs to 1,000 cfs) during this work could save a significant amount of water and, hence, power revenues. A "back-of-the-envelope" estimate indicated that decreasing releases during this time to save water for when the powerplant was operational again would save approximately 5 ft of water, 34,000 acre-feet and $85,000 in power revenues. Katrina highlighted that this was a very rough estimate. UPDATE: a more detailed analysis after the meeting estimates a savings of approximately $60,000 in power revenues.

Katrina described a potential fall release pattern and requested feedback from the meeting participants on how this pattern might affect them. The following pattern was discussed: Aug to Sept 15th: 1,200 cfs; Sept 15th to Dec 1st: 1,000 cfs; and Dec 1st to April 1st: 1,325 cfs (perhaps lower, depending on observed inflows). Katrina noted that the plan would keep flows stable at 1,000 throughout the fish spawning seasons and that the increase would occur prior to typical icing of the river. Meeting participants noted that 1,000 cfs is higher than past years baseflows and that increasing flows is not detrimental to the fish like decreasing flows can be. Robb Keith of the Wyoming Game and Fish mentioned that the September through March spawning periods are critical periods for brown trout and kokanee salmon.and that the fish need stable flows through the winter, especially after ice forms over the river. He noted that decreasing flows after the ice forms can cause an ice shelf to fall, trapping eggs and fish in the backwaters without oxygen exchange.

Meeting participants also noted that the river is typically covered in ice around December 15th, however, in some years the river can ice up as early as mid-November. Increasing flows after the ice has set on the river can cause ice jams and the potential for flooding at downstream communities. The question was rasied whether an increase of 300 cfs would cause ice jams. This is currently unknown, but meeting participants indicated that it was unlikely. However, most thought it would be prudent to increase flows before the ice is fully set. Once icing begins, it usually takes about two weeks before it is fully set. Katrina proposed monitoring and adjusting releases on-the-fly when the ice begins to form. Through communication with Robb Keith, Bryan Seppie and others beginning mid-November, Reclamation will be aware when the ice is starting to form and can increase releases gradually as soon as icing begins. Meeting participants requested a press release in addition to the normal email notification to help inform the public about the increase in releases.

Robb Keith noted that duck hunters would not typically expect a increase at this time of year and could lose decoys. After the meeting Robb expressed a safety concern that duck hunters could get accustomed to wading across the river at certain locations, and, depending on the location, an icrease from 1,000 to 1,325 could be a significant increase is velocity and depth. He indicated that communication and notification is the best means to keep the public safe and informed.

Emergency Response Exercise:  Judy Valentine, coordinator for the Sweetwater County Emergency Management Team, communicated with Reclamation that they are planning to do a functional exercise for emergency response for Fontenelle Dam next year. Judy was unable to make the working group meeting, but communicated with Katrina prior to the meeting. Judy noted that they may begin with a tabletop setting and then later expand each element as time and resources permit. Katrina notified the working group of her discussions with Judy and that there may be a functional exercise next year.

Low Flow Impacts: Katrina Grantz described the National Integrated Drought Information System (NIDIS) project to collect data on the impacts of low flows and drought. Katrina passed along information and a request from Melissa Widhalm of the National Drought Mitigation Center (NDMC) regarding the "Low Flow/Stage Related Impacts in the Upper Colorado River Basin" project. The project is sponsored by the National Weather Service and the National Drought Mitigation Center to enhance the current Weather Service river forecasting system to forecast low river level warnings for locales, and to include information on corresponding impacts that may be expected as river levels decline in the future. The NDMC is collecting information from local experts on the potential impacts associated with low river levels near each of ninety selected sites in the Upper Colorado River Basin. The responses will be organized into a database for incorporation into the current Weather Service forecasting system. Katrina requested information from Fontenelle Working Group meeting particiapants regarding low flow/stage impacts at several locations in the Upper Green River Basin including below Fontenelle Dam and at the City of Green River. Mike Meyer of the Jim Bridger Power Plant provided information about the level below which the pump station can no longer pump water (400-450 cfs). Ed Boe of the Wyoming State Engineer's office provided information after the meeting.

Stilling Basin Maintenance: Steve Hulet of Reclamation provided an overview of the stilling basin maintenance work that took place in April and May. A reusable rubber bladder coffer dam was used in the dewatering, cleaning and inspection of the stilling basin. Steve noted that the work took longer than originally anticipated due to issues with the pumps, but that the basin was cleaned of large cobble and Reclamation is still waiting for the final report on the results of the inspection. Chuck Green of Reclamation and Robb Keith of Wyoming Game and Fish worked together during the dewatering to rescue any stranded fish in the stilling basin during this work. No fish were killed during this project. Steve Hulet also mentioned that Chuck Green retired in June and Reclamation is currently working to hire his replacement.

Proposed Regional Watershed Supply Project:  Hank Castillon, mayor of the City of Green River, spoke about the City's concern about the proposed Regional Watershed Supply Project (Aaron Million's proposed pipeline out of Flaming Gorge Reservoir and the Green River below Fontenelle Dam.) Hank noted that the cities of Green River and Rock Springs and Sweetwater County have formed a cooperative agreement to join together and pool their resources in an effort to oppose the proposed pipeline or any other inter-basin water transfer project which seeks to remove water from teh Green River and transfer it to another drainage basin.

Next Meeting

The workgroup’s next meeting is scheduled for April 27, 2010 at 10am at the visitor's center at Seedskadee National Wildlife Refuge below Fontenelle Dam.

Attendees

Name

Organization

Katrina Grantz Bureau of Reclamation
Ed Vidmar Bureau of Reclamation
Steve Hulet Bureau of Reclamation
Allan Wilson City of Green River
Mike Meyer Jim Bridger Power Plant
Robert Keith Wyoming Game and Fish Department
Hank Castillon Mayor of City of Green River
Bill Reed Colorado Basin River Forecast Center
Rusty Dickson Qwest
Jackie Stout Qwest
Ed Boe WY State Engineer's Office
John Beyer US Fish and Wildlife
Ben Bracken Joint Powers Water Board
Bryan Seppie Joint Powers Water Board
W. Russ Findlay Bureau of Reclamation

Email comments/inquires to: ResourceMgr@usbr.gov