Colorado River Storage Project
Fontenelle Working Group
April 22, 2008
This meeting was held at the Seedskadee National Wildlife Refuge on the Green River below Fontenelle Dam. Attendees are listed below.
The purpose of operation 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.
Peter Crookston called the meeting to order at 10: 10 a.m. with 15 present. Peter introduced himself and said that Ed Vidmar was unable to attend. He said that the existing condition and hydrograph analysis and forecast would be presented by Katrina Grantz. Rick Clayton introduced Katrina and said she will be taking over his responsibilities in Fontenelle Dam operations. Following Katrina’s presentation and some discussion, Natalie Muth with the Utah Division of Wildlife Resources gave a presentation on aquatic invasive species. Before starting, all present introduced themselves and their affiliations.
Katrina’s hydrology presentation began with a summary of what occurred in the past, current conditions and then the forecast. She said full reservoir capacity is 345,000 acre feet (af). The present volume is 104,500 af, so there is a lot of room in the reservoir. Maximum elevation is 6506 feet (ft); current elevation is 6466 ft which leaves 40 ft available storage for spring runoff.
Snow pack is at 92% of average for this time of year. Earlier in April it was at 95% of normal. Because the basin is still very dry it is expected that a lot of the runoff will be absorbed in the soil. The 30-day temperature forecast predicts normal temperatures, therefore runoff is expected to occur at normal times. The April-July runoff forecast predicts that the most probable runoff volume this year is 705,000 af, or 82% of average. The 90% exceedance volume is 475,000 af (i.e., there is a 90% chance flows will be above this volume and 10% chance runoff will be below.) The 10% exceedance volume is 980,000 af. So we expect an average year for inflow volume. Last year the forecast was quite accurate and was very close to the observed runoff.
Katrina showed a most probable inflow graph based on the 30 year hydrograph (1976-2005) showing the minimum and maximum, and most probable. She also showed a graph of the projected Fontenelle Dam release scenarios of minimum, maximum, and most probable. Last year the reservoir reached 6490 ft elevation so it did not completely fill. This year the reservoir is expected to fill with a bypass beginning in late May and ending in the middle of July.
Chuck Green said the powerplant capacity is determined by reservoir water elevation. At the current elevation of 6466 the unit gate is 40% opened with an inflow of 1000 cubic feet per second (cfs) to 1100 cfs. Turbine capacity increases to 1700 cfs to 1750 cfs at 6500 to 6506 feet elevation. The gate limit is 80% and probably will not be opened 100%, although theoretically it could be opened to 100% at elevation 6476 ft. The gate has to be closed when the water level falls below 6463 ft.
Robert Keith with the Wyoming Game and Fish Department said the reservoir is small relative to the river inflow so it is managed year to year almost as run-of-the-river with a bypass almost every year.
Chuck Green added that in the past the reservoir would fill and spill every year, but Reclamation does not operate this way any more. Fontenelle does not spill very often because Reclamation now brings the reservoir down every year to accommodate the spring inflow. There is not a lot of flexibility with this small of a reservoir.
Katrina said the minimum release ramping up rate is 200 cfs per day with a ramping rate of 50 cfs stages. Ramping down is kept in check in order to not strand fish. For last year’s operations Reclamation discharged through the powerplant units only (i.e., without bypass). By operating guidelines the reservoir elevation is kept below 6500 ft until July 1 st in order to keep a cushion in case of a high inflow event.
Ben Bracken of Joint Powers Water Board said that at the water treatment plant they are susceptible to turbidity so they appreciate small ramp rates coming out of Fontenelle.
Mike Besson of the Wyoming Water Development Commission (WDC) expressed concern that when the storage level is below 120,000 af, they might not be able to meet an immediate request for water. WDC has a water right of 120,000 af and, ideally, they would like for Fontenelle to always have 120,000 af so they could draw on that right at any time. Katrina said that current storage is 104,500 af and elevation is 6466 ft. Releases will not be increased until the reservoir reaches 6468 ft, thus the reservoir is expected to gradually increase until the bulk of spring runoff starts. Rick Clayton added that the current storage and elevation levels are a result of the constant release rate of 700 cfs that was agreed upon at the last working group meeting in August 2007.
Mike Besson also asked Reclamation to extend rip rap down lower along the dam for protection when the water level is drawn down. At low water levels (below the existing rip rap) the dam can be damaged by water action against the unprotected surface. Dead pool (the level below which water cannot be released) is 540,000 af, or an elevation of 6460 ft .
Chuck Green discussed a maintenance project scheduled for this summer. He said the stilling basin has concrete damage and the dentates have exposed rebar. The rock basin needs to be inspected as well. On July 11 th Reclamation plans to deploy a coffer dam 300 feet from the end of the stilling basin. The coffer dam is made of polypropylene (rubber). The dimensions are 250 feet long, 6 feet tall and 19 feet wide. Reclamation plans to dewater the stilling basin by drawing out about 2 feet per day, 12 to 13 days of pumping are expected. The stranded fish will be salvaged and the surface will be washed down to see the damage and determine what work is required. Reclamation plans to dewater again the following year and do the fix.
Rick Clayton said the reservoir is full in July and a big rain event could force Reclamation to use the spillway. Rick requested that Chuck consider doing the dewatering and project inspection in late summer (August or September) when there is more room in the reservoir to handle a large rain event. At that time there is less of a chance the coffer dam would have to be quickly removed.
Chuck said he would consider doing the inspection later in the summer.
The group reviewed the ramp rate standard again. It is 50 cfs per day at low flows and then up to 100 cfs per day when releases are 900 cfs to 1000 cfs. When releases are at or above 2000 cfs the acceptable ramp rate is 200 cfs per day and even up to 500 cfs per day. These ramp rates are for ramping up. Ramping down rates might be different (smaller).
Peter thanked everyone for their comments. He agreed to allow everyone an opportunity to review the meeting notes by email before they are put on the internet.
Natalie Muth with the Utah Division of Wildlife Resource (UDWR) gave a presentation on aquatic invasive species ( New Zealand mud snail and the Quagga mussel) threatening our waters.
Utah is the second driest state in the Country. Our water ways are critical to our way of life. Quagga mussels, a small clam like bivalve mollusk, came to the West from the Black and Caspian Seas by ship ballast water. They arrived at the Great Lakes 22 years ago and are now up to a foot thick on the bottom of the lakes. They have caused large bird die offs and large fish kills. Quagga mussels are filter feeders and filter huge amounts of water. One female can produce up to one million eggs per breading season. They damage pumps, filters, boats, pipes, canals, and recreation equipment. The cost from damage is in the millions of dollars. They are a huge threat to dams and powerplants as well as the native ecosystem.
They were first found in southern California in 2007 and are now in Lake Mead, Nevada. Natalie showed a cross section of a water pipe at Lake Mead full of mussels. She said they are reproducing like crazy in Lake Mead, can survive in water depths of 400 feet deep, and can live out of water for 30 days. No natural predators that can control them exist here in the West. Their natural predator in the Black and Caspian Seas is a piscivorous (fish eating) fish that could be very harmful if introduced in the West.
Utah is fighting the problem aggressively with a Utah Emergency Action Plan. The objective is to prevent the spread of these species to other waters. Utah purchased 26 portable decontamination units ($12,000 per unit) to wash off boats and facilities. We need everyone, especially water managers, to be aware of the problem.
Peter announced the tentative date for the next Fontenelle Working Group meeting to be on Tuesday, August 19, 2008, at 10 a.m. at the Wyoming Department of Fish and Game in Green River Wyoming.
Fontenelle Working Group Meeting Minutes:
|Ed Boe||WY State Engineers Office|
|Mike Meyer||Jim Bridger Powerplant|
|Mike Besson||WY Water Development Comm.|
|Chuck Green||USBR-Fontenelle Dam|
|Joseph J. Erranbusye||JPWB|
Email comments/inquires to: ResourceMgr@uc.usbr.gov