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Often the lake exceeds the full pool owing to lack of coordination between the dams coupled with the complexities of wind and temperature-driven internal circulation events and patterns. Flathead Lake is an extremely large, deep lake and therefore its hydrodynamics are profoundly influenced by Coriolis and density currents and circulation patterns in addition to volume regulation by the dams. The lake has a 30 km wind fetch on the long axis and storms and shoreline erosion rates exceed 2 m per year (lineal cross section) at the north end of the lake where the shoreline is dominated by deltaic sand substratum. Surface and internal seiches are common after storms and may influence the pattern of sediment transport from eroding shorelines. As a consequence of these natural (wind) and human (lake level regulation) disturbances, the 970 ha depositional delta of the Flathead River has entirely eroded into the lake within the last 50 years; littoral and riparian communities of the lakesho?e have also been vastly altered, if not partially uncoupled from processes in the main (pelagic) part of the lake (Bauman 1988, Hauer et al. 1988, Lorang et al. in press). The negative effects of both Kerr and Hungry Horse operations have been carefully documented (see review by Stanford in press) and a mitigation plan for hydropower impacts (e.g., fluctuating flows and lake levels, temperature changes, migration barriers, habitat and production losses, accelerated Lakeshore erosion) on fish and wildlife resources has been proposed to regulatory authorities. In this case two different regulatory authorities exist. The Federal Energy Regulatory Commission is currently considering a plan related to Kerr Dam, since it is operated by private concerns. Owing to its operation by a Federal agency, mitigation of impacts related to Hungry Horse Dam fall under the mandates of the Northwest Power Planning Act of 1984 for the entire Columbia River Basin which involves the Northwest Power Planning Council (planning) and the Bonneville Power Administration (research and implementation). The mitigation plans were jointly developed by the State (Montana Department of Fish, Wildlife and Parks), the Tribes and the entities that operate the dams, with input from university scientists and other agency biologists. Proposed actions include: retrofitting Hungry Horse Dam to allow selective withdrawal to facilitate more natural temperature regime downstream; construction of re-regulation dams or operational changes to moderate flow fluctuations from Hungry Horse and Kerr Dams; reducing the full-pool level of Flathead Lake to reduce shoreline erosion; revetment of some shorelines to curtail erosion and enhance wetland development for waterfowl; habitat restoration in damaged fish and wildlife production areas; and hatchery supplementation of fishes as replacement for losses associated with hydropower 18