Scoping Assessment for Developing a Water Quality Monitoring Plan to Support Application of the CE-QUAL-W2 Hydrodynamic and Water Quality Model to the Lower Missouri River downstream of Gavins Point Dam.

摘要

The Missouri River Mainstem System (Mainstem System) is comprised of six dams and reservoirs constructed by the U.S. Army Corps of Engineers (USACE) on the Missouri River, and where present, the free-flowing Missouri River downstream of the dams. The six reservoirs impounded by the dams contain about 73.3 million acre-feet of storage capacity and, at normal pool, an aggregate water surface area of about 1 million acres. The six dams and reservoirs in an upstream to downstream order are: Fort Peck Dam and Fort Peck Lake (MT), Garrison Dam and Lake Sakakawea (ND), Oahe Dam (SD) and Lake Oahe (ND and SD), Big Bend Dam and Lake Sharpe (SD), Fort Randall Dam and Lake Francis Case (SD), and Gavins Point Dam and Lewis and Clark Lake (SD and NE). The Mainstem System is a hydraulically and electrically integrated system that is regulated to obtain the optimum fulfillment of the multipurpose benefits for which the dams and reservoirs were authorized and constructed. The Congressionally authorized purposes of the Mainstem System are flood control, navigation, hydropower, water supply, water quality, irrigation, recreation, and fish and wildlife (including threatened and endangered species). The Mainstem System is operated under the guidelines described in the Missouri River Mainstem System Master Water Control Manual (Master Manual) (USACE-RCC, 2006). Flow in the lower Missouri River is largely determined by the discharge of Gavins Point Dam, especially so during low-flow periods.