Council approves realignment project of salmon-bearing Tosh Creek adjacent West Lake Sammamish Parkway

Award of Bid to TriState Construction, Inc. in an amount of $1,207,448.85 for Tosh Creek Realignment and Culvert Replacement

Tosh Creek is a Class 2 (salmon-bearing) stream that flows off a steep hillside and meets

the valley floor at West Lake Sammamish Parkway (WLSP), where it flows through an

arch culvert approximately 67 feet in length. The channel downstream of WLSP has been

ditched and relocated around a field. The lower stream reach has limited in-stream

habitat and the stream bank vegetation is mostly blackberry. During heavy rains, the

culvert occasionally exceeds capacity, flooding WLSP and requiring debris and sediment

removal from the inlet and outlet each year.
 

Small numbers of Coho salmon spawn in the stream regularly, and the stream supports

healthy numbers of rearing juvenile Coho as well as Cutthroat trout. With restoration, the

stream has the potential for some of the best small-stream salmon habitat in the southwest

quadrant of the City.  Read More >>

The project goals include the following:

1. Enhance fish passage and in-stream habitat;

2. Improve stream buffer function and reduce invasive weeds;

3. Reduce City maintenance and increase natural sediment transport terrace stream

channel to reduce flooding potential; and

4. Accommodate future road widening and trail connections and reduce future

mitigation requirements.

Project Description:

The final design services has been completed, permits and property rights have been

secured and the project advertised for bids.
 

The Tosh Creek Realignment and Culvert Replacement project will realign approximately 600 linear feet of stream channel and provide 125 feet of culvert replacement improvement that meets fish passage requirements and accommodates future road widening along with necessary utility adjustments.

Construction activities will begin in early July of this year and extend through fall 2013. The

relatively short construction window is due to the fact that the majority of these

improvements must be constructed when stream levels and fish activity are low.

Reported by Bob Yoder
Source:  Consent Agenda, 6/17/2013