Upper Klamath Lake

Upper Klamath Lake is a large, shallow freshwater lake east of the Cascade Range in south-central Oregon in the United States. The largest body of fresh water by surface area in Oregon, it is approximately 25 miles long and 8 miles wide and extends northwest from the city of Klamath Falls. It sits at an average elevation of 4,140 feet.

In the early 20th century, most of the wetlands and marshes surrounding the lake were drained for agricultural purposes, damaging the larger habitat. The lake's water has been used to support the federal Klamath Project for irrigation by local farmers for a century. The lake depth fluctuates due to regulation of its water supply, averaging between 8 to 50 feet deep.