Services:

Woodson Creek Stream and Wetland Mitigation Site Development

Issue:

OASIS created wetland mitigation sites (banks) for the Montana Department of Transportation (MDT) to provide credits that offset the loss of wetlands caused by road construction. The Clean Water Act requires mitigation for any loss of wetlands resulting from construction activities. Due to the scale and varied locations of MDT's planned highway construction, its wetland mitigation needs were substantial.

Solution:

OASIS identified a previously converted wetland on a private property near Ringling, Montana that was ideally suited for wetland restoration. OASIS and MDT entered into a Wetland Credit Agreement to provide MDT with 44.4 acres of wetland mitigation credits. This site was converted to farmable land in the late 1960's by channelizing a highly sinuous reach of Woodson Creek and filling old channel meanders. The associated riparian area was cultivated and seeded to non-native cultivars.

OASIS prepared restoration designs that included developing appropriate planform, profile and cross-section for the creek and developed a floodplain grading and revegetation plan. Work tasks included geomorphic assessments and channel classification, reference reach characterization, flood frequency analysis, bedload characterization and hydraulic modeling. All applicable federal, state and local permits were obtained by the design team. OASIS also provided oversight during construction. A performance standards and crediting ratio proposal was developed and is currently used as a supporting document for the site's 5-year monitoring program. All applicable federal, state and local permits were obtained by the design team.

Results:

The Woodson Creek Wetland Mitigation Site was completed in the spring of 2006 and is currently in its first year of monitoring by MDT. Field evaluations have shown significant increases in the extent of wetland hydrology and numerous shore birds and waterfowl species have been observed using the site. Also, several waterfowl species have successfully raised broods on the site. The reconstructed Woodson Creek channel and floodplain experienced a significant flood in the spring of 2007 with no adverse effects.

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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