Spatial Analysis of Chinook Spawning Habitat: GIS Analysis of Warm Water Intrusion Below Iron Gate Dam; Klamath, California

The Klamath River supports several species of salmon including Steelhead, Coho and Chinook. Historically, Klamath has been the third largest producer of salmon on the West coast and an integral part of the California fishery, supporting commercial, recreational and tribal communities. Within the past decade, however, water quality conditions on the Klamath have declined due to increased temperatures and nutrients, depressed dissolved oxygen and elevated turbidity; prompting the EPA to list the Klamath as an impaired river. The effects and spatial extent of elevated temperature below Iron Gate Dam on Chinook salmon spawning were evaluated using ArcMap 9.2 in conjunction with nine USGS gauging stations. Potential habitat layers were derived from DEM and relative bed stability indices. Through the process of Dynamic Segmentation, habitat and water quality were combined and available spawning habitat were quantified. Dynamic Segmentation converts linearly referenced data stored in a table into features that can be displayed and analyzed on a map. By overlaying and intersecting potential salmon spawning habitat layers with water quality the amount of available habitat can be quantified along a linear feature. Analysis indicates reduction of spawning habitat by 24% due to warm water intrusion. This approach also allows for an assessment of the potential impacts on habitat suitability under different climate change scenarios.