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Mitigating for roads, environment

From the District 4 newsletter, Interchange
For ITD, planning the future of roads, leading to land takeovers and expansion, often results in disturbances to the fragile ecosystems of Idaho. More important is finding practical ways to make up for those disturbances.

In District 4, there have been only a handful of road expansion projects recently that required wetland or water mitigation – making up for lost or destroyed wetlands – which is a requirement of both the Army Corps of Engineers and Federal Highway Administration, according to D-4 Environmental Planner Dan Armstrong. The amount of created wetland depends on both the size and quality of wetland being destroyed.

“It depends on the hydrology, plant life and other factors,” Armstrong said. “They (FHWA and the Army Corps) want to build roads too, they have the taxpayers’ interest in mind too, and that’s what we should be doing.”

Four such projects – only one of which is completed – currently need mitigation: the City of Rocks Back Country Byway, Shoshone North (Idaho 75), U.S. 93 from Interstate 84 to Idaho 25, and Gannett Road to Silver Creek (U.S. 20). Three mitigation projects have been used to recover more wetlands than are being affected, including protection of a creek bed from cattle in Castle Rocks State Park near Elba, creation of sediment ponds in Jim Byrne Slough near Richfield, and relocation of a U.S. Forest Service road that ran through Cove Creek near Hailey.

D-4 Project Manager Bob Johnson said these mitigation projects were not only saving valuable lands, they were also practical.

“One of the environmental groups wanted us to buy a lake and protect it. The landowner wanted $500,000. We worked with the (Big Wood) Canal Company and spent $13,000 on Jim Byrne Slough,” Johnson said. “It was a group effort to get it done from the idea to talking to the canal company and FHWA.”

Even an area as small as 45 square feet, as was the case on U.S. 93 from I-84 to Idaho 25, requires mitigation.

“We used an agreement with the Idaho Department of Parks and Recreation (in Castle Rocks) to fence off an area where the cows were getting in,” Johnson added. “We protected 10 acres, and it was enough for two mitigation projects.”

Photo: Project Manager Bob Johnson takes photos of settling ponds on Jim Byrne Slough near Richfield. The ponds will help keep field sediment out of the Little Wood River.