Restoration & Rehabilitation
The enclosed Environmental Assessment (EA) has been prepared for securing the Chadbourne Diversion. This proposed action combines the interests of native fish conservation and irrigated agriculture. By securing the Chadbourne Diversion, water users served by the Lower Shields River Ditch would continue to receive water according to their water rights. The fisheries component would promote the persistence and protect the genetic integrity of Yellowstone cutthroat trout occupying approximately 375 miles of mostly connected stream habitat. The aging Chadbourne diversion suffers from several structural problems that threaten its long-term stability. Moreover, it has features that allow rainbow trout to breach the dam which threatens the genetic status of the Yellowstone cutthroat trout in the watershed above. Consequently, Montana Fish, Wildlife & Parks (FWP) is collaborating with the Lower Shields River Canal Company on a series of proposed repairs and retrofits. The repairs would include addressing erosion and wear on the face and abutments, and elimination of a large scour hole that threatens to undermine the structure. The fish passage elements would include installation of retrofits to prevent passage of fish through an existing notch and elsewhere along the face of the dam. In addition, construction of a selective fish passage channel would allow native Yellowstone cutthroat trout to access the river upstream of the diversion whereas nonnative fishes would be returned to the river below. This document is an environmental assessment (EA) of the potential consequences of the various alternatives. EAs are a requirement of the Montana Environmental Policy Act (MEPA) which requires state agencies to consider the environmental, social, cultural, and economic effects of proposed actions. This EA considers 3 alternatives: 1. repairing the structure and installing retrofits and the selective fish passage channel 2. no action, and 3. repair of the structure without implementing the fisheries components. Montana Fish, Wildlife & Parks invites you to comment on the attached proposal. The public comment period will be accepted until 5:00 p.m. August 10, 2012.