Lake Chelan users this fall may notice that the lake drops slightly faster than in previous years as Chelan County PUD puts into place a new month-by-month plan for lake levels that was approved as part of a new 50-year license.

On Sept. 7 each year, the lake is expected to be about 7 inches below the average of the past 20 years, which has been a surface elevation of 1,099.5 feet above sea level. The highest the lake ever reaches at any time is 1,100 feet.

Lower levels in the fall are designed to help small streams that flow into the lake scour out gravel and sediment barriers at the mouths that sometimes block native fish access to the tributaries for spawning.

Higher levels in the spring (May and June) are expected to boost recreation opportunities by having the lake fill faster for the summer season. The new average elevation for June 1, for example, is expected to be almost 10 inches higher than previously.

Summertime levels (July, August) should remain virtually unchanged.

Under normal circumstances, Lake Chelan will continue to drop faster in the fall after Labor Day. For example, the new average level is expected to be about 11 inches lower on Oct. 1 and to be about 18 inches lower on Nov. 1.

Chelan County PUD had its new 50-year license for operating Lake Chelan approved by the Federal Energy Regulatory Commission in November 2006. The license was developed over eight years of collaborative studies and negotiations by parties including the U.S. Forest Service, the U.S. Fish and Wildlife Service, the National Park Service and groups of Lake Chelan residents and property owners who helped design the new lake level targets.

Several other conditions in the new license can also affect how lake levels are managed. The PUD is required to maintain a minimum flow of 80 cubic feet per second in the Chelan River below the dam, and that requirement has higher priority than minimum/maximum lake levels. The PUD must also try to keep flows in the Chelan River from going above 6,000 cfs to the extent feasible (whenever water must be spilled through the Gorge) because higher flows can cause erosion and damage new fish habitat being created in the lower stretch of the river where it nears the Columbia.