The water level in Red Willow Dam is "about where it's going to be for the next couple of years until we get it fixed," an official said Thursday.
Marv Swanda, of the U.S. Bureau of Reclamation, gave an update of the dam at the 2010 Southwest Water Conference Thursday in McCook.
A hole about 18 inches across and 14 inches deep was discovered in October 2009 and water was drained to investigate the problem.
About 150 gallons of water dyed blue was poured in the hole, so the extent of the damage could be determined.
At least three cracks have been found, ranging in size from one millimeter to a half inch.
Swanda said the problem has developed over time and may have started years ago.
The pipe used to drain the lake when it was constructed in the early 1960s was placed on solid bedrock, while the adjacent dam was built on more compressible riverbed material. Through the years, the structure settled at different rates, resulting in the cracks.
Swanda speculated that ways to fix the problem could be a sand/gravel filler blanket on the downside of the dam or to take the cut-off wall down to the foundation and build it back up with a grout curtain.
As for the projected time-line to fix the dam, "We'll compress an 18-month process into a year," Swanda said.
A corrective study done by a team of engineers will continue until the fall, he said, after which alternatives will be evaluated. A preferred method will then be selected and submitted to Congress for funding. Once funding is approved, contracts can be awarded with repair to start by summer 2011.
Because funding will be provided under the Reclamation Dam Safety Act, which covers 85 percent of the cost, Congress has 30 days to act once the project is submitted. If it does not act, funding is automatically approved.
Swanda wouldn't comment how much the repair would cost, but estimates have been in the millions.