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Dunham Creek

Location of Dunham Creek in the Blackfoot Watershed

Dunham Creek, a second-order tributary flows 13 miles through an alluviated glacial valley, joining Monture Creek at stream mile 11.5. Stream discharge was measured at 32 cfs on July 15, 1996. The channel is composed of laterally moving sand, gravel and cobble substrate, with a riffle/pool habitat sequence in the mid to lower reaches. Portions of the stream are unstable with both aggraded and incised reaches. 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. Dunham Creek ranked 11 of 83 streams surveyed.

Dunham Creek before restoration at stream mile 4.2
Stream mile 4.2 (Photo taken in 1974)
Photo #1
Stream mile 2.2 on Dunham Creek at an irrigation canal
Stream mile 2.2
Photo #2

The poor condition of the Dunham Creek fishery is a result of altered and unstable stream channels caused by poor riparian timber harvest practices and subsequent channelization (Photo #1) which may cause the stream to go sub-surface during base flows; and entrainment of native fish into an irrigation canal (Photo #2). In 1995, the loss of westslope cutthroat trout, juvenile bull trout, and a spawned, radio-tagged bull trout to this canal were documented.

Self-cleaning fish screen located just below head-gate on Dunham Creek
Self-cleaning paddle wheel fish screen.
bar graph showing bull trout and cutthroat trout densities increasing from 1996 to 1998 in Durham Creek
In the fall of 1996, the canal was fitted with 19 cfs self-cleaning paddle wheel fish screen. In 1998, 10 bull trout redds were located in Dunham Creek above the fish screen. The graph above shows densities of bull and cutthroat trout (Fish > 4.0") before and after screening the irrigation ditch.

Stream mile 2.3 is just above the irrigation ditch and just below the bull trout spawning siteThis section of the stream was not logged or channelized and is in excellent condition. Stream mile 4.2 is the logged and channelized reach shown above in Photo #1.

Dunham Creek at stream mile 2.3
Stream mile 2.3
In 2000, we completed the reconstruction of 1.3 miles of Dunham Creek to natural channel dimensions consistent with a stable alluviated (C4-type) channel. Before the project, mean bankfull width in the degraded project reach was 62.2 feet compared to mean stable reference reach bankfull width of 37.1 feet. The width/depth ratio of the reference reach was 22.4 compared to 59.1 in the project reach. Sediment deliveries in the project area were 25 times the natural levels. This influx of unnaturally high levels of sediment entered the channel immediately upstream of the Dunham Creek bull trout spawning area.

The restoration project focused on channel reconstruction with emphasis on natural channel morphology, habitat complexity and included an aggressive revegetation of disturbed banks. The primary objective of the project was to stabilize the stream to allow riparian vegetation to encompass the stream over a 10-15 year period and thus provide long-term stability.

     installing rootwads into the bank   discussing stream restoration with Dave Rosgen

Fish Populations

We resurveyed fish populations at two monitoring sites (mile 2, 3 and 4.2) in Dunham Creek before channel reconstruction. Both sample sites show lower native fish densities in 2001 compared to earlier surveys. These recent population declines likely result from low flows (related to drought) and a large influx of fine sediment (primarily sand) in spawning riffles downstream of the channelized reach. Post-project monitoring will be conducted to assess the effectiveness of this restoration project.

Bull trout spawning in Dunham Creek
Spawning bull trout

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