Archive for March, 2015

For the past 5 years, Confluence has been working with the Beaverhead Watershed Committee, Montana Fish, Wildlife and Parks, and the Dillon Canal Company on the Poindexter Slough Fisheries Enhancement Project near Dillon, MT. When completed, this project will improve fish habitat and flows through 4.75 miles of Poindexter Slough, a popular fishing destination due to lengthy, publicly accessible segments of the stream to anglers.

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New screw gates at head of Poindexter Slough

Following several years of planning, permitting, and fundraising, construction of the Poindexter Slough restoration project began in January 2015 with replacement of a headgate on the Beaverhead River to improve the flow of water in the Slough. The new headgate allows flow to be increased up to 200 cubic feet per second (cfs), promoting more sustainable habitat by flushing fine sediments, scouring deep pools, rejuvenating spawning habitat, and increasing aquatic insects. Base flows ranging between 20 and 50 cfs will be diverted into the Slough during most times of the year to provide more consistent year-round flows and generate water velocities and stream depths optimal for spawning, rearing, and angling.

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Pool excavation and fine sediment removal in Upper Poindexter Slough

 

Pool habitat was enhanced in the upper 2.25 miles of the Slough by removing fine sediments that had accumulated in the channel over several decades, and by reconfiguring the spacing, location, and dimensions of pool and riffle features. In addition, a 2,000-foot segment of the Slough just upstream of the fishing access was re-graded and narrowed to eliminate backwatering and sediment deposition caused by an old check dam that diverted water down the Dillon Canal. The check dam and headgate for the Dillon Canal were replaced with new structures placed at a lower elevation to prevent backwatering and fine sediment accumulations upstream in Poindexter Slough, while maintaining the ability to divert water down the Dillon Canal during the irrigation season. This highly acclaimed fishery is expected to rebound over the next five years.

 

A final phase of habitat enhancement in Poindexter Slough is planned for the lower 2.5 miles of channel downstream of the Dillon Canal to the confluence with the Beaverhead River. The Beaverhead Watershed Committee is in the process of securing funding for this phase, which is 100% publicly owned and managed by Montana Fish, Wildlife, and Parks. As warmer weather inspires you to get outdoors, be sure to put Poindexter Slough on your bucket list of places to visit. Contact Katie Tackett, coordinator for the Beaverhead Watershed Committee at beaverheadwatershed@gmail.com, or by visiting BWC’s website if you are interested in learning more about the project or donating to the cause!

Before

Over-wide segment of Poindexter Slough with eroding bank

After

Segment of Poindexter Slough narrowed to improve sediment transport and fish habitat. Photo taken immediately after construction.