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Salmon Creek

Location map for Salmon Creek in the Blackfoot Watershed

Salmon Creek, the outlet stream to Coopers Lake, flows 1.7 miles to its union with Dry Creek and eventually forms Rock Creek a tributary to the North Fork of the Blackfoot River. Salmon Creek contributes the majority of the upper Rock Creek discharge during base flow periods. Coopers Lake is a 300-acre oligotrophic, glacially-formed lake. Due to natural regulation of flow from the surface of the lake, Salmon Creek maintains fairly stable flows, very clean substrate, low turbidity and low levels of nutrients. Immediately downstream of the outlet, Salmon Creek enters a steep, heavily forested canyon where it cascades through confined step/pool series of boulders and cobble. Gradient drops quickly at the mountain-Kleinschmidt Flat interface.  Salmon Creek enters Spawn Lake, a small irrigation reservoir. Downstream of Spawn Lake, Salmon Creek is an impaired low gradient, slightly sinuous, meadow stream with gravel substrate. Base flows average around 11-16 cfs in Salmon Creek.

The fishery in Salmon Creek is impaired due to poor fish passage, losses of fish to irrigation canals, dewatering of the stream channel, channel alterations and past streamside management. The Spawn Lake outlet structure regulates irrigation withdraw from Spawn Lake and prevents the upstream movement of fish. One quarter mile downstream of Spawn Lake, another irrigation canal diverts additional flow from the stream. This diversion structure also inhibits the upstream movement of fish. Both diversions entrain fish.  During the month of June, these diversions take 13-19 cfs from the stream to irrigate approx. 410 acres.

Habitat in lower Salmon Creek has been impacted by alterations to the channel and past land-use practices.  Lack of instream woody debris has reduced habitat complexity. Rock dams exist, creating a widened channel, simplifying habitat, and causing deposition of fine sediment. A corral adjacent to the stream has damaged the streambank and contributed sediment and animal wastes to the stream. A 2,000 foot section of middle Salmon Creek also was channelized, creating a linear, uniform stream lacking habitat features. The channelization also drained a natural 130 acre instream wetland on Salmon Creek. In order to prioritize restoration resources, we developed a fisheries-based restoration priority scorecard, based on biological, social and financial considerations, for 83 impaired tributaries of the Blackfoot River. Salmon Creek is ranked 21 of 83 streams surveyed.

In 1996, restoration efforts began in the Salmon Creek watershed. Restoration activities have included: constructing a fish ladder on the Spawn Lake irrigation diversion; installation of an infiltration gallery (fish screen) on the upper irrigation ditch; removal of the lower irrigation diversion and replacement with a rock weir structure to allow upstream migrations and bedload transport; installation of a self-cleaning paddle wheel fish screen on the lower ditch; instream habitat restoration on one mile of stream; complete channel restoration of the channelized reach to a E4 stream type; restoration of the 130 acre drained wetland; fencing 1.5 miles of Salmon Creek; removal of the livestock corral from Salmon Creek; and a conservation easement protecting the restored wetland and lower Salmon Creek.

Spawn Lake irrigation diversion before restoration
Spawn Lake irrigation diversion
before restoration.
Spawn Lake irrigation diversion after restoration
Spawn Lake irrigation diversion
with Denil fish ladder.
 

Salmon Creek before restoration
Salmon Creek - overwidened and
lacking habitat before restoration.

 

Salmon Creek after restoration photo
Salmon Creek after restoration.

 

Aerial view of the channelized
reach and restored wetland
one year after restoration.
Aerial view of Salmon Creek restoration

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Blackfoot Valley Watershed
Montana Partners for Fish and Wildlife
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Mountain-Prairie Region
U.S. Fish and Wildlife Service