Submitted to: Arkansas Soil and Water Education Conference
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2001
Publication Date: N/A
Technical Abstract: Grenada Reservoir was commissioned in 1954 as part of a comprehensive plan for flood control in northwestern Mississippi. Two rivers contribute inflow to the reservoir. Total watershed drainage area is approximately 3,419 square kilometers (1,320 square miles). Reservoir life expectancy was originally estimated at 25 years because of high erosion rates. However, the lake continues to function with only slightly reduced storage capability. Reservoir and watershed sediments were sampled in 1998 and 1999. Sediment accumulation within the permanent pool adjacent to the dam was generally less than 1cm/yr. The central area of the permanent pool has experienced sediment accumulation rates averaging less than 1.5 cm/yr. Sites within the two reservoir arms fed by the river inflows showed little or no sedimentation. Sedimentation rates within Grenada Reservoir were higher until the mid 1960's & early 70's but were considerably lower thereafter. These lower sedimentation rates paralleled land use changes and followed discontinuance of major upstream channel alterations for flood control. In spite of long-term historical use of residual pesticides in the watershed and widespread use of currently applied agricultural compounds, concentrations in stream or lake sediments and overlying water were generally low or not detectable. Conversely, several metals (arsenic, lead, copper, iron, aluminum and zinc) were abundant in stream and lake sediments.