Kootenai River White Sturgeon Spawning Habitat With Free Flowing and Backwater Conditions that Meet Depth and Velocity Criteria, 2006-10

The U.S. Geological Survey developed, calibrated, and validated a multidimensional flow model for simulating streamflow in the white sturgeon spawning habitat of the Kootenai River in Idaho. The USGS MultiDimensional Surface-Water Modeling System was used; the model was developed as a tool to aid understanding of the physical factors affecting quality and quantity of spawning and rearing habitat used by the endangered white sturgeon (Acipenser transmontanus) and for assessing the feasibility of various habitat-enhancement scenarios to re-establish recruitment of white sturgeon. Kootenay Lake, British Columbia, Canada, creates backwater conditions that extend upstream into the spawning habit.  The extent of backwater in the spawning reach is a function of river flows upstream of the backwater reach and Kootenay Lake levels and this creates a complex relation between stream discharge and depth and velocity. Model simulations were used to identify reaches that met the minimum depth and velocity criteria during the May and June 2006-10 spawning seasons as stipulated in the U.S. Fish and Wildlife Biological Opinion. The analysis of depth and velocity provides important data to assist in designing habitat improvement actions regarding endangered fish; however, the modeling methods can be applied to a wide range of issues.