This project included evaluation of the upper Trail Creek watershed following an approximately 100 year flow event and subsequent failure of an earthen berm, which had impounded a fourteen-acre area encompassing the channel and its floodplain. The dam failure sent a torrent of water and debris downstream. Five years after the flood event approximately 80% of the watershed, upstream of the site, burned in the 2001 Fridley Fire.
Our team evaluated the impacts caused by these natural and artificial events and established restoration alternatives. A priority project was identified within the historic lake basin where the rapid drawdown of the lake resulted in vertical down cutting of the channel into the lake bed sediments. Associated head cuts had migrated through the valley and the stream had begun to laterally erode at the time of the assessment. The result of multiple impacts to the system is an unstable, deeply entrenched and straight channel configuration through the lake basin. Design activities included identification of restoration alternatives, flood frequency and channel hydraulic analysis, characterization of a reference reach, design of channel bank treatments, grade control and floodplain grading. Project team secured through a Montana Fish, Wildlife & Parks (MFWP) Future Fisheries Improvement Program with matching funds from the landowners for construction of the project.
This Priority I restoration established a new channel alignment at the historic floodplain elevation. Channel construction methods included the use of a combination of log / debris jams, fabric encapsulated soil lifts and native sod. The restoration will be part of a native cutthroat trout reintroduction effort. As a result of the dam failure flooding, a natural fish barrier was formed in a bedrock canyon reach downstream of the project site and the fires of 2001 have possibly sterilized the upper drainage of a viable fish population. Therefore the sequence of natural and artificial catastrophic events has provided a rare opportunity to restore a native trout population without direct competition from non-native fish. MFWP will conduct electro-fishing surveys to verify fish population, or the lack thereof, and will reintroduce native Yellowstone cutthroat to the upper watershed. As a condition of the project funding, MFWP will implement a temporary fishing closure until the fishery establishes a healthy Yellowstone cutthroat trout population.
Tom Coleman directed watershed analysis and design activities. DeWitt Dominick provided project construction management and technical support for all design activities.