Foster Lake level rises after initial repairs to dam

Sean C. Morgan

Of The New Era

The U.S. Army Corps of Engineers reported good news Monday: Foster Lake is on the rise.

The lake level will come back up some 10 feet, to 622 feet above sea level, putting both the Sunnyside and Gedney Creek boat ramps in the water. Calkins Park boat ramp will remain above the waterline.

The bottom line is the Corps’ emergency work last week has bought down some of the risk of keeping lake levels up for recreation, said Erik Petersen, operations project manager for the Willamette Valley Project. The Corps is now able to ease some of the limitations on recreational use of the lake.

Lake levels have been rising ever since the Corps finished work on gates two through four Friday afternoon, he said.

The Corps started lowering the lake level on July 15 to make repairs on the gates. By July 28, the level had dropped to about 612 feet.

This allowed Corps workers to climb down and inspect the gates and lubricate the trunion bearings in gates two through four, Petersen said. The Corps had a “hiccup” on July 28 when the contractor’s crane broke down and had to be repaired. It was online by Wednesday.

By late Thursday evening, crews had greased the bearings and exercised the gates to the full range of their motion, he said, and engineers said the gates could handle a pool of 622 feet.

“It certainly provides more accessibility for recreation,” Petersen said. “It puts recreation back on the late while still managing the risk.”

The Corps couldn’t risk having the gates off-line if one or both of the power generating units were to break down, he said. The only way for the dam to move water is through the spillway or the power generators.

With the gates out of action, losing a turbine would mean no water flowing into the stream below, he said. “We need the redundancy, and we have both of those right now.”

In the meantime, Corps engineers are analyzing the structural members of the gates. The structural members are metal beams that stretch from the bearing to the actual gate. The gates swing open and shut on the trunion bearings.

All four of the gates have deformed structural members caused by friction in the trunion bearings, Petersen said. The Corps would like to accelerate the repair or replacement of those before flood control season.

Flood control season begins with the rainy season, sometime between mid-October and December, Petersen said. Initially, the Corps will repair or replace the structural members of gates three and four; and based on receiving funding, Corps officials would like to get right to work on gates one and two, the northernmost gates.

That will make the dam fully functional in all but the most extreme conditions, Petersen said.

When the Corps is ready to finish repairs on gates three and four, the Corps will pull the lake back down to around 613 feet, he said, but that won’t happen before the end of the recreation season in September.

Normally, the lake is taken down slowly, reaching winter pool sometime in November.

The Corps hasn’t decided whether to heat and repair the structural members or replace them, Petersen said, but the most likely solution is replacement.

The gate repairs are estimated to total $7 million.