SEATTLE --The June 1 updated forecast for Koocanusa Reservoir indicates approximately 50 percent of the watershed’s high elevation snow pack remains in the mountains. As a result of this updated forecast, U. S. Army Corps of Engineers water managers may need to begin a limited flood control spill at Libby Dam as early as June 10.

This limited flood control spill is expected to maintain adequate flood control storage in Koocanusa Reservoir to reduce the risk of a larger flood control spill later in June or early July. An objective of the Corps’ planned operation is to avoid exceeding Montana’s water quality standards for total dissolved gas saturation, when possible.

Much of the high elevation snow pack remains even after May’s unusually warm weather and the subsequent low elevation runoff during the past two weeks, which caused near flood-stage high water in the Kootenai River below Libby Dam and flooding on the Yaak and Moyie rivers in Montana and numerous rivers in Idaho.

The Corps’ water management strategy takes into account the need to provide flood protection to the region, the Corps' responsibilities concerning Endangered Species Act listed and resident fish and aquatic life located downstream of Libby Dam, and other important local and regional considerations.