By Joyce Edlefsen
ASHTON — As the Henry’s Fork continues to drop over the Chester Dam, construction crews are working on both shores of the river on a project that could improve the fishery and produce 3.3 megawatts of power.
Fall River Rural Electrical Cooperative Manager Bryan Case says work on the more than $15 million project has gone relatively smoothly since the project began major excavation work last spring.
Anglers used to seeing mainly waterfowl and other anglers get a completely different view now of the area near Fremont-Madison Irrigation District’s Chester Dam. For decades the dam has served as a diversion structure to get water into the small Last Chance Canal on the south shore of the river and the larger Cross Cut that takes off from the north shore.
Headworks for both of the canals will be improved and fish screens and fish returns installed as part of the project through a settlement agreement signed by the Fall River REC, Fremont-Madison Irrigation, the Idaho Fish and Game, the Henry’s Fork Foundation and many other players interested in an improved fishery resulting from the project.
This week visitors to the dam will see heavy equipment and crews working to repair and improve the headgates of the Last Chance Canal and doing preliminary work on installing concrete for fish screens and returns from the canal on the south side of the river.
In the huge hole excavated on the north side of the river, the intake wall with three large circles is taking shape. Three turbines are expected to arrive at the site in December, and crews will begin to install them in January, Case says.
The turbines could produce as much as 3.6 megawatts of power at maximum output and maximum cubic feet of water. But under an agreement reached with the entities and agencies that signed the Federal Energy Regulatory Commission settlement, the turbines will run at a maximum of 3.3 megawatts with the previously agreed water flow of 3,500 cubic feet per second – at least initially.
Case says the walls for the powerhouse where the water will exit also are under construction in the deep hole. Hammering and other construction noises mix with the geese honking as they fly up and down the river overhead.
While the busy season for outfitters and other boats is over on the river upstream of the dam, a takeout site is still available for float boats. A new bridge and detour around the huge piles of materials from the hole allow anglers access to the river upstream.
Fall River REC hopes to begin generating power at the dam in April 2011, but the project won’t be complete until the fall of 2011 when the rubber dam will be placed across the top of the existing dam, Case says.
“So far, everything has been going mostly according to plan,” he says.
Ashton Dam outflow to be increased Monday
Rocky Mountain Power announced that on Monday, outflow from Ashton Reservoir will be increased by approximately 200 cubic feet per second above inflow to the reservoir. This will cause the reservoir level to decline approximately 1 foot per day to test generating equipment at low reservoir levels.
That rate will be maintained through Friday or until elevation 5,147 is reached. The reservoir is currently at 5,152 elevation.
Starting Nov. 17 outflow will be reduced approximately 200 cubic feet per second below inflow to begin refilling the reservoir approximately 1 foot per day. This will be maintained through Nov. 21.