Elk Creek, a
third-order tributary, flows 14 miles northwest through a mineralized section of the
Garnet Mountains before entering the Blackfoot River at river mile 28. Its base flow
is approx. 4 cfs. Extensive mining, including a century of placer mining in the
upper drainage, has severely altered the channel. This land use, combined with
channelization, road construction and maintenance activities, and poor drainage problems,
continue to contribute large amounts of sediment to the stream.
Sections within the lower
5 miles of Elk Creek riparian corridor have been heavily grazed, creating unstable stream
banks. One mile of channel, from stream mile 1.8 to 2.8, was moved from its original
location for irrigation in the 1940's. The channel was placed in the upland along the
valley wall in glacial lake sediments. The result was vertical channel incision up to
10 feet that produced steep, highly erodible banks. The amount of stream channel
sediment in this section was as much as 900% greater than an upstream control section.
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. Elk Creek ranked 17 of 83 streams surveyed.
Restoration efforts at two locations in
Elk Creek began in 1991. An upstream project directed by the BLM, reconstructed a B4
Channel in an area severely impacted by dredge and placer mining.
In the lower portion of the
Creek, initial efforts focused on restoration of the channelized reach, which involved
reconstructing a 8,581 foot section of E4 channel type. This project involved moving
mature willows from adjacent areas, adding large woody debris, filling in the channelized
reach, implementing a deferred rest-rotational grazing system with cross fences and
Further improvements to the management
of riparian areas are currently being considered on public and private lands through-out
the drainage. Changes in stream profile, temperature, sediment and fisheries
responses are being monitored for both projects.