The Klamath River spans California and Oregon and is important habitat for salmon and other fish. The river also is listed as impaired for several criteria including nutrients and organic enrichment/low DO. Therefore, the California State Water Resources Control Board, the North Coast Regional Board, and EPA are working to establish TMDLs and numeric nutrient endpoints for stretches of the Klamath River. Multiple modeling approaches were used in this evaluation of the river.
The BATHTUB model was used as a simple screening tool to predict average nutrient conditions in the Klamath River. The researchers found agreement between BATHTUB predicted values and both observed and CE-QUAL-W2 modeled results. They used those predictions to strengthen criteria recommendations for TP, TN, and chlorophyll a. The researchers also used QUAL2K and a revised QUAL2K modeling method to investigate the relationships between algal density, chlorophyll a, and other nutrient conditions. Information from both the QUAL2K models and BATHTUB modeling was used to inform criteria recommendations for the Klamath River (Tetra Tech 2008).
Reference:
Tetra Tech (Tetra Tech, Inc.). 2008. Nutrient Numeric Endpoint Analysis for the Klamath River, CA. Prepared for U.S. Environmental Protection Agency Region 9 and North Coast Regional Water Quality Control Board. Accessed October 2016. http://www.waterboards.ca.gov/plans_policies/docs/nutrients/nne2_klmth.pdf EXIT.