Change of target elevation over time:
It is a widely believed misconception that the target elevations were lowered following the flood of 1993. This probably arises from the contrast between the mild weather of the past few years and the frequent excursions of the lake level past the flood stage throughout the early 1990's. However, the original target elevations were 670 feet in the spring for flood control, and 680 feet in the summer for water conservation. Revisions of the target levels were made in 1963, 1982, and 1992, in each case raising the level in response to the gradual siltation of the pool. The 1963 revision also introduced the concept of a higher fall pool to benefit waterfowl. A positive byproduct of the revisions has been a gradual increase in the surface area of the lake available for boating. The reduction of the flood control pool volume due to siltation since the dam was finished in 1958 has been about 10%, and has been only a relatively small contributor to the decreased flood control ability of the dam. In 2000, an additional review was completed and the dates of reduction for the spring melt drawdown have been slightly modified.
Corps of Engineers target outflows (by season):
If you wish to see the exact regulations of outflow for "Normal Flood Control Operation", "Major Flood", and "Drought", click Here.