The Lake Roosevelt Rainbow Trout Habitat/Passage Improvement Project is a resident fish substitution project intended to mitigate for anadromous fish losses caused by the construction and operations of Chief Joseph and Grand Coulee Dams. The goal of the project is to increase natural production for Tribal subsistence.  This substitution of resident fish for anadromous fish losses is considered in-place and out-of-kind mitigation and is in accordance with the Resident Fish Substitution Policy.
The Project proposes to enhance natural production and survival of resident fish for recreation and Tribal subsistence with the implementation of several management actions designed to address habitat related limiting factors and restore the natural hydrologic function of the systems. EDT and QHA sixth level HUC analysis indicated the greatest limiting factors for most of the Sanpoil and Upper Columbia Subbasin’s tributaries were identified in the Subbasin plans as obstructions, summer temperatures, flows, and sediment load (IMP Subbasin Plan 2004). Additionally nutrient imbalance limits growth and diversity with most streams being both nitrogen and phosphorus limited.
The land uses that have contributed to these limitations include cattle grazing, timber harvest, road construction and density, cut bank roads, irrigation withdrawal, restrictions of the natural channel migration with culverts and bridges, removal of riparian vegetation, agriculture, mining, and the loss of carbon and marine derived nutrients from anadromous carcasses.
Man-made passage barrier have limited the access to spawning and rearing habitat that would have otherwise been used by rainbow trout. Many of these barriers in the Sanpoil Subbasin have been previously revised or removed by this project where protection of remnant native redband populations genetics was not a concern. During 1990-1991 the initial phase of the project focused on the assessment of limiting factors following assessment of 27 streams five streams were selected for improvements. Between 1992 and 1995 project personnel conducted implementation of designed stream, passage, and habitat improvements. Those improvements were monitored from 1996 through 2000. In 2000 Bridge Creek was selected for the next improvements and the work was completed in two phases in 2004. Additional work completed includes the removal of a passage barrier on Roaring Creek in 2003 and Thirty Mile Creek in 2005. The stabilization of 1000 feet of actively eroding bank along the Sanpoil River was also completed in 2005 and damage to existing structures caused by peak flows in the spring of 2006 were completed on South Nanamkin, Bridge Creek, and Thirty Mile Creek. Monitoring of stream temperatures and flows continues and stream surveys have identified the previously unknown spawning grounds for large percentage of the adfluvial rainbow trout population as well as the discovery of genetically pure populations of native redband rainbow trout in several locations across the Colville Reservation's streams.
Several strategies have been developed to achieve the projects goal of enhancing/improving the natural production of adfluvial rainbow (native salmonid stock) trout in tributaries to Lake Roosevelt. Work Elements have been designed to maintain and enhance water retention in the individual watersheds, reduce sediment addition, restore riparian vegetation, restrict the access of cattle to the riparian areas, reduce temperatures, enhance selected areas of habitat, and return marine derived nutrients to the ecosystem. These actions will address the limiting factors determined in the QHA Subbasin Assessments the proposed work elements will reduce factors limiting the production and growth of rainbow trout in the Colville Reservation portions of the Sanpoil and Upper Columbia Subbasins.