In order to evaluate impacts to the temperature of the mainstem Columbia and Snake rivers, EPA Region 10 has developed a dynamic, one-dimensional heat budget model (RBM10) of the basin. While EPA continues to apply RBM10 using long-term records (tributary inflows/temperatures, meteorology, etc.) to evaluate temperature variability over time, this report focuses on detailed monitoring information collected by the Columbia River Inter-Tribal Fish Commission (CRITFC) and Fisheries and Aquatic Sciences in the early 1990s at 18 locations in the Snake River. This data is used to evaluate questions about the underlying assumptions and performance of the RBM10 model, including: (1) Does available data support the assumption, inherent in one-dimensional temperature analysis, that cross-sectionally averaged temperatures are uniformly transferred through dams; (2) To what extent do surface temperatures deviate from the cross-sectional average temperature, and are these deviations influenced by flow augmentation from Dworshak reservoir; (3) How do RBM10 model simulations compare to measured cross-sectionally averaged temperature of the Snake River; and (4) How do RBM10 model simulations compare to measured temperatures under the dynamic conditions associated with flow augmentation from Dworshak reservoir.

"September 2002." Includes bibliographical references (p. 9).

"EPA has recently evaluated water temperature regines of the mainstem Snake river using transect measurements and the RBM10 one-dimensional heat budget model (Cope, 2001)... In this report, the two-dimensional CE-QUAL-W2 model framework developed by the U.S. Army Corps of Engineers (Cole and Buchak, 1995) is used to simulate temperature regimes in Lower Granite Pool, from the confluence of the Clearwater and Snake Rivers to Lower Granite Dam. The study period is July through October of 1992 ..."-- Introduction, p. 1. Introd.