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Grayrocks Reservoir fully recovers
For the first time in nine years, the Grayrocks Reservoir is full. The man-made lake that supplies water to the Laramie River Station near Wheatland, WY, reached 100-percent capacity on May 28.
Basin Electric Power Cooperative - June 4, 2010
For the first time in nine years, the Grayrocks Reservoir is full. The man-made lake that supplies water to the Laramie River Station near Wheatland, WY, reached 100-percent capacity on May 28. The last time the reservoir was full was in June 2001.Grayrocks reached its low point in January 2008, when it was only 10 percent full, containing 10,400 acre-feet of water. The reservoir’s capacity is 104,000 acre-feet. An acre-foot of water is the amount of water it takes to cover one acre of land one foot deep. One acre-foot of water is equivalent to 325,828 gallons.
Scott Woolsey, Laramie River Station civil engineer III, says the lack of water at Grayrocks forced the power plant to supplement its water supply with water from owned wells and leases from other wells and the Wheatland Irrigation District. Leased water was pumped to the power plant’s raw water pond through a series of overland pipes. Between October 2004 and May 2010, more than 80,000 acre-feet of water was delivered to Laramie River from leased sources.
Woolsey says bringing in water has been a challenge. “One of the major obstacles was figuring out how to get the pumps to operate together as a system and deliver the volume of water the plant was consuming at the time,” he says. “We had to coordinate it this way because our raw water pond doesn’t have a large capacity – 800 acre-feet – compared to Grayrocks.”
Laramie River operations staff also had to closely monitor the flow of water through the overland pipes to prevent freezing in the winter, he says. Also, water treatment plant operations had to be significantly changed to accommodate the less-than-optimum quality of the water being piped to the plant.
Grayrocks has been slowly recovering since 2008, but precipitation over the past three months has boosted the reservoir’s levels quickly. Inflows from tributaries jumped from a few hundred cubic feet per second early in the year to a peak of about 2,300 cubic feet per second on May 21.
Woolsey says despite the challenges of maintaining water supply to Laramie River over the past several years, it has been an interesting project. “We were doing something that hadn’t been done, at least on this scale, in the history of Wyoming. We had to act fast since levels were declining so quickly at the beginning, and we had to get past those who said, ‘It’ll never work.’”
He says it’s also been a good opportunity to examine and improve the operation of the water treatment plant for better performance in the future.
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