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Title:	Water Quality Modeling Report : Simulation of Fort Peck Lake Temperature Releases and Downstream Missouri River Temperatures
Authors:	United States. Army. Corps of Engineers. Omaha District
Keywords:	Water quality--Mathematical models Hydrodynamics--Mathematical models Computer simulation Fort Peck Lake (Mont.) Missouri River Environmental management Environmental protection
Publisher:	United States. Army. Corps of Engineers. Omaha District.
Abstract:	Due to low annual runoff in recent years and low pool levels, the U.S. Army Corps of Engineers was unable to perform a “mini-test” followed by a “full test” of discharge and temperature enhancements to the Missouri River downstream of Fort Peck Lake. In lieu of actual flow and temperature enhancements, the U.S. Army Corps of Engineers, Omaha District performed computer simulations of both Fort Peck Lake and the Missouri River to analyze temperature conditions under flow/temperature enhancement operations. Temperatures in Fort Peck Lake and the Missouri River downstream of Fort Peck Dam were simulated using CE-QUAL-W2, a two-dimensional (longitudinal and vertical) water quality and hydrodynamic model for rivers, estuaries, lakes, reservoirs, and river basin systems. CE-QUAL-W2 was developed by the Environmental Laboratory at the USACE Engineering Research and Development Center (ERDC) in Vicksburg, MS. Baseline temperature conditions in the lake and river were developed through simulations of existing data; and, the sensitivity of parameters that influence lake and river temperature including lake inflow and outflow, pool elevation, and environmental temperature was determined. Simulations of spillway releases and selective tower withdrawals were performed to analyze the effectiveness of releasing warm water downstream to the Missouri River in order to meet the 18°C target temperature at Frazer Rapids, MT, as prescribed by the 2000 U.S. Fish and Wildlife Service Biological Opinion. In the baseline lake simulation 17°C temperatures, sufficient for meeting the 18°C temperature target at Frazer Rapids, MT, arise at the lake surface and spillway crest elevation between June 20 and 22 and persist for 96 days. Lake water near the existing powerhouse intake structure does not reach 17°C during any simulation year. The average simulated Missouri River temperature from June through August was 13.2°C at Frazer Rapids with a peak daily temperature of 17.3°C. In the parameter evaluation, low pool elevations and high environmental temperatures caused higher overall Fort Peck Lake pool and discharge temperatures. Similar sensitivity results were produced in the Missouri River simulations. During spillway “full tests”, the 18°C water temperature was first achieved at Frazer Rapids, MT, on June 24 meeting the target for 37 days at an average temperature of 18.1°C; however, 0.92 million acre-feet (MAF) of additional water was spilled from the lake. In an alternate spillway release the temperature target was first achieved on June 28 meeting the target for 47 days at an average temperature of 18.2°C over the entire release period with only 0.08 MAF of additional water spilled. Tower withdrawals achieved 18°C temperatures for 70 days when all water was passed through the withdrawal tower inlet near the lake surface, and 18oC temperatures were achieved 37 days when water was passed through both the existing and selective withdrawal tower. Tower withdrawals did not require additional water to be spilled from the reservoir because all water was passed through the powerhouse.
Description:	Technical Report
Rights:	Approved for Public Release; Distribution is Unlimited
URI:	https://hdl.handle.net/11681/48274
Appears in Collections:	Technical Reports