Grant County — Boaters were reportedly told to remove their boats from an area of Moses Lake Thursday as crews from the Moses Lake Irrigation and Rehabilitation District worked to construct a temporary fix for the Moses Lake Dam located along Sand Dunes Road.
There is no danger to property owners in the area and there are signs up to stay 500 feet away from the area, according to Curt Carpenter, of the MLIRD.
A Grant County Sheriff's Office marine deputy was positioned near the 85-year-old earth dam Thursday where a temporary cofferdam is being constructed along the north outlet structure on Sand Dunes Road south of Moses Lake following a sinkhole discovered over Labor Day weekend.
Carpenter said the dam is being undermined and material under the dam has been carried away, which created the sinkhole. Carpenter said the process is something that can't be seen on the surface until it's too late.
On Thursday and into Friday morning, crews constructed the 125 feet long temporary cofferdam using sheet piling, a process of interlocking pieces of steel on both sides of the dam, to stop the water flow. An employee from the Bureau of Reclamation was also on scene during the construction.
As of Thursday evening, Carpenter said crews were about 65 percent finished with the process of constructing the cofferdam to "mitigate the hydraulic action" caused by the water. He said he expects the construction to be completed sometime Friday morning.
Carpenter said the cofferdam is temporary and core drilling will need to be done before the next phase is decided.
About three years ago, Carpenter said another sinkhole was created in the area and reported to the MLIRD Board. Design work was started on a new structure but required a five to 10 year plan, and the plans were cut out of the budget for the past two years.
Carpenter said it may take a few days to determine when Sand Dunes Road will be reopened.
In 2010, the MLIRD installed new gates at the dam to hold water in the lake, according to a March 25, 2010 Columbia Basin Herald article.
The rails the gates were running on were corroded.
At the time, the project cost about $250,000.