MWDA Fish Passage

Fish passage is being achieved at the MWDA diversion with the installation of seven rock weirs. The contractor has been working on these weirs since the beginning of November. Yesterday they were completed and the creek was turned back into it's channel!

This is a significant milestone for the project because most of the remaining work, except for modifications the headgate, are out of the Manastash Creek channel. With the weather and stream flow becoming more unpredictable, it was important to complete the weirs and get out of the creek.

This is the MWDA diversion in full operation in April 2008. This fish passage issue is not only the checkboards in the dam, but also the concrete apron below the dam.

This photo is taken from the left bank looking upstream toward the diversion dam after the channel was dewatered, but before any of the weirs were constructed. The creek bypasses the work site by flowing down the MWDA ditch and then in a dug channel back to the creekbed below where the weirs are being constructed.

The rock weirs include large rocks that are carefully selected to fit together in the weir structure. This photo shows one completed weir and work on the next upstream weir.

This photo is taken from the right bank looking upstream toward the diversion dam. The rock weirs span the full channel and have low flow notches that resemble stair steps. This photo is looking upstream toward the concrete dam (where the excavator is sitting).

This is looking downstream from the diversion dam after the creek was turned back into it's channel yesterday afternoon. The rock weirs blend nicely into the stream channel.

AL

Coleman Creek Project

The Coleman Creek project is nearly complete. The project included removing the existing concrete diversion dam and pump vault and replacing them with rock weirs for fish passage, a headgate above the upper weir, a fish screen, and a new pump vault. Work began the last week of October and is expected to be completed by early December.

This is the diversion structure during the '09 irrigation season. It was a barrier to fish passage and was unscreened.

The reach of the creek where the work occurred was dewatered and then a fish salvage occurred. Above are Ryan and Sara from the District and Jen Scott from WDFW with an electrofisher. They work for quite a while to remove all the fish under the existing diversion dam.

The first order of business was to remove the old diversion dam.

The rock weirs were constructed, beginning with the apex rock.

Below each rock weir, a scour pool was excavated.

The new pump vault was set in two pieces by a large crane.

The water was released back into the creek.

The remaining work includes finishing the gates, the fish screen installation and all the automation for the water measuring.

AL