MOSES LAKE - Moses Lake Irrigation and Rehabilitation District officials may end up moving the Moses Lake North Dam downstream rather than make repairs to the existing structure.

The dam and the road across it have been closed for more than a month after a sinkhole was discovered near the structure over Labor Day weekend, according to a previous Columbia Basin Herald article.

MLIRD crews then installed an emergency cut-off wall (cofferdam) to take the hydraulic pressure off the dam.

At the time, MLIRD General Manager Curt Carpenter said the cofferdam was only a temporary fix and core drilling and testing would have to be done before a next step was decided.

Carpenter recently told board directors that engineers have completed testing and site inspections and concluded the dam was essentially in failure mode. The dam would either need to be repaired or replaced, he said.

The current dam was built around 1929, according to information from the district. While age is a factor in the dam's decline, other factors have played a role over the years, Carpenter said.

He said weight and vibrations from the traffic over the structure have also taken on a toll on the dam because it was never engineered for that kind of activity.

Carpenter told directors it would be more cost effective to build an entirely new dam and tear down the current one than to fix the dam and keep it in the same location.

"Underneath (the dam) is so saturated and compromised, you lost your footing and your base," he said during a MLIRD board meeting earlier this week. "You would have to reconstruct your sub-grade."

The ground beneath the dam is compromised as far down as 40 feet, Carpenter said. And at that depth, it's pure sand, he said.

"We're in the process of looking at what the best route is," said Carpenter. "But the initial educated guess, looking at what they found, is saying that it's going to be a pretty major expense to put out to rebuild that sub-grade."

Carpenter said if the dam were to be moved downstream, the district would build the new structure, get it in place and then take out the current dam. The new dam would need to be installed by the end of March, he said.

Right now, the entire project is estimated to cost about $2.3 million, Carpenter said. He said local legislators, including Reps. Doc Hastings, R-Wash. and Judy Warnick, R-Moses Lake., and other agencies are currently working to secure emergency funding for MLIRD so the financial burden doesn't fall on rate payers.