Spencer Lake, located in San Juan County, Washington, is a private hydroelectric reservoir with a dam completed in 1983. The dam, primarily designed for hydroelectric purposes, also serves as a fish and wildlife pond and a recreation area. With a maximum storage capacity of 3,117 acre-feet and a normal storage capacity of 3,038 acre-feet, Spencer Lake covers a surface area of 74 acres and has a drainage area of 2.4 square miles.

Managed by the Federal Energy Regulatory Commission, Spencer Lake's dam stands at a height of 42 feet and spans 120 feet in length. The controlled spillway, with a width of 11 feet, helps regulate water levels and prevent overflow during periods of high discharge. Classified with a low hazard potential and a very high risk assessment rating, the dam has a prescribed inspection frequency of every 3 years to ensure its structural integrity and operational safety.

Surrounded by the natural beauty of Washington state, Spencer Lake offers a serene environment for outdoor enthusiasts and water resource aficionados alike. Its vital role in providing renewable energy through hydroelectric power, supporting local wildlife habitats, and offering recreational opportunities makes it a valuable asset in the region's water resource management efforts.