A Hydrodynamic And Water Quality Model Of The Lower Klamath River, California, For The Management Of Fish Mortality

Ceratonova shasta, a myxosporean parasite, has been responsible for high mortality of salmonid fishes in the Pacific Northwest of North America. Water temperature is an important factor that affects C. shasta related mortality in salmonids. The objective of this study is to develop a comprehensive model for predicting areas in a river channel with unique conditions of flow discharge, velocities, and water temperature that increase the risk of C. shasta related mortality in salmonids. Such a model will be a valuable tool for decision makers to use when identifying management actions that could decrease disease effects in salmonids. A three-dimensional hydrodynamic model of the Lower Klamath River from Iron Gate dam to Seiad Valley was developed using the Environmental Fluid Dynamic Code (EFDC). A Lagrangian particle transport and CE_QUAL_W2 temperature model were integrated into the hydrodynamic model to track dispersion of waterborne parasite spores along the river and predict the water temperature. This paper will demonstrate how model results have been used to not only provide a better understanding of the water quality conditions and parasite spore transport in 2015, but to also test the effects of several scenarios on the water quality and disease risk to salmonids in the river basin.