Environmental Management Program: Long Term Resource Monitoring Program, Upper Mississippi River System. Identification of Constraints on Regulation of Upper Mississippi River System, Lock and Dam 18

摘要

The study undertook the identification of constraints on a one foot pool raise at Mississippi River Lock and Dam 18. Pool 18 is approximately 26.5 miles long with a thalweg gradient of 0.28 foot per mile. A pool raise, as measured at the dam, would have variable spatial effect depending on main stem and tributary discharge which creates a sloping water surface at all but extreme low flow conditions. At low or no flow conditions, a one foot pool raise at the dam would flood shoreline vegetation throughout the pool. At the most probable flow the fall migration period, a one foot pool raise could flood approximately 300 acres of low elevation and shoreline vegetation in the lower 16 miles of the pool. Constraints identified for water level manipulation in Pool 18 were limited Federal real estate interests, and the structural capability of Lock and Dam 18 to maintain any pool elevation over the elevation of the overflow spillway.