Workers moved a large crane to the banks of the Spokane River near the Monroe Street Dam to move gravel and cobble that has clogged the dam’s intake structure.
“During high flows, during spring run-off, a lot of gravel and cobbles flow downstream and stack up,” said Speed Fitzhugh, Spokane River license manager for Avista. “When you have a really high-flow water year, like this year, rocks have a tendency to bounce along the riverbed.”
Later this week, Avista will begin its work to move up to 1,000 cubic feet of rock and stone from behind the dam, using a clamshell bucket crane to dump the rock on the downriver side.
Fitzhugh said the work will begin Thursday and will take up to three weeks to complete. The accumulation interferes with power production, but the gravel is also habitat for trout spawning below the dam.
The work is not that complicated. The bucket will grab a load, turn and dump the cobble and gravel on the other side of the dam.
“We take out the garbage,” he said. “The grocery carts and signs.”
The dredging was to begin on Monday, but was postponed due to a mechanical problem with the crane.
Huntington Park will remain during the duration of the project.