Services:

Chadbourne Diversion Dam Fish Passage Study

Issue:

The Chadbourne Irrigation Diversion Dam on the Shields River near Clyde Park, Montana was degrading and at risk of failure. Upstream of the diversion, many tributaries to the Shields River have native populations of Yellowstone cutthroat trout. Montana Department of Fish, Wildlife & Parks (MTFWP) was concerned that failure of the structure would allow upstream migration of non-native rainbow trout, which will hybridize with the cutthroat species. MTFWP needed an assessment of structural integrity of the diversion and an evaluation of the structure as a fish passage barrier.

Solution:

OASIS conducted the hydraulic analysis and fish passage assessment of the structure over the range of expected flows in the Shields River. Fish passage assessment included analyzing the conditions and flow rates at which Yellowstone cutthroat, brown, brook and rainbow trout are able to pass from the Yellowstone River across the diversion dam into the Upper Shields River Basin. Tasks included surveying, hydrologic field assessment, flood frequency analysis, hydraulic modeling and compilation of fish passage assessment methods.

Results:

OASIS’ analysis found that the diversion is currently an upstream migration barrier to all species and life stages of trout and concluded that failure of the structure would be potentially harmful to native fish populations upstream of the structure. OASIS produced a report summarizing findings for MTFWP that will be used to secure funding to upgrade the structure.

Case Studies

Montana Department of Fish, Wildlife & Parks

Scientists from OASIS identified an isolated population of genetically pure native westslope cutthroat trout...
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Montana Department of Transportation

OASIS created wetland mitigation sites (banks) for MDT to provide credits that offset the loss of wetlands caused by road construction...
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Private Landowners

The owners of the PMD Ranch and the Nelson Spring Creek Ranch had interest in restoring a small unnamed spring creek...
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Montana Department of Fish, Wildlife & Parks

The Chadbourne Irrigation Diversion Dam on the Shields River near Clyde Park, Montana was degrading...
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