CE-Qual-W2 Temperature Modeling USACE, Portland District (OR)
Under four Task Orders, WEST Consultants, Inc. was tasked by the Portland District, U.S. Army Corps of Engineers to investigate impacts to downstream temperatures due to releases from nine reservoirs in the middle reaches of the Willamette River. The Oregon Department of Environmental Quality (DEQ) is currently developing a CE-QUAL-W2 model of the Willamette River and its main tributaries in order to produce temperature Total Maximum Daily Loads (TMDLs).

Under a previous IDIQ contract with the Portland District, WEST Consultants used CE-QUAL-W2 to develop temperature models of Hill Creek Reservoir; Lookout Point/Dexter Reservoirs; and Green Peter/Foster reservoirs. Under our current IDIQ contract, we developed temperature models of Dorena, Cottage Grove, Fall Creek, and Fern Ridge Reservoirs. Each model was calibrated and validated to observations, and then run for 30-35 years to simulate the historic range of flows and atmospheric conditions. The data analysis included the development of regression equations to either estimate inflow temperatures using nearby USGS streamflow temperature data, or using air temperatures to estimate inflow temperatures.

Version 3.7 (beta) of CE-QUAL-W2 was used to blend the withdrawals from a reservoir to meet downstream in-stream temperature targets for fish habitat. The study includes estimating the change is temperatures released from Hills Creek reservoir, and influenced by tributaries, as inflows temperatures to Lookout Point Reservoir. In addition, we are evaluating a number of blending strategies including (1) blending from two existing outlets, (2) release from a single elevation of a multi-port tower, and (3) blending releases from two elevations of a multi-port tower.