Twin Creek has a long history of mining, including historic prospecting and placer mining beginning in the early 1900s. There are over 60 closed mining claims on record in the Twin Creek drainage. The mines on Twin Creek have since been abandoned by the operators and left in an unreclaimed condition. Due to this past mining activity, Twin Creek has been heavily altered, especially in the lower reaches near its confluence with Ninemile Creek. Specific problems include excessive erosion, channel dewatering and piles of dredged material (gravel, large cobbles, etc.), which occupy much of the valley bottom and impede the function of the floodplain. Many of the instream and riparian mine tailings remain unvegetated and contribute large sources of sediment to the creek.
Because of these disturbances, Twin Creek lacks a functional connection with mainstem Ninemile Creek. Fish and other aquatic organisms have been prevented from upstream migration for more than 70 years. The creek is also a large sediment producer into Ninemile Creek. Historic mining impacts throughout the Ninemile Creek drainage and the associated plumes of fine sediment and bedload sediment have led to an unstable stream channel, which is moving throughout the floodplain and impacting roads, home sites, pastures and other infrastructure.
The overall goal of the project is to reconnect Twin Creek to Ninemile Creek and the upper reach of Twin Creek, which is currently in good condition. Upper Twin Creek has a stable stream channel, with complex fish habitat, fish populations dominated by native westslope cutthroat trout and favorable water temperatures. TU is working with the Lolo National Forest, Missoula County and private landowners to plan the restoration project. The project will involve large scale earthworks, stream channel reconstruction and revegetation activities.