Upper Klamath Lake

Nestled in the heart of south-central Oregon, Upper Klamath Lake is a marvel of natural beauty and ecological significance. Known to the Klamath as ?ews, meaning “lake,” this expansive body of water is the largest in Oregon by surface area and plays a crucial role in the region’s ecology and human activity.

Geography and Hydrology

Spanning approximately 25 miles in length and 8 miles in width, Upper Klamath Lake is situated east of the Cascade Range, near Klamath Falls. It lies at an elevation of 4,140 feet and is fed by a 3,768 square mile watershed, including the Williamson and Wood Rivers. The lake’s primary outflow is the Klamath River, flowing south from the lake.

The lake’s surface area covers 61,543 acres, with an average depth of 14 feet, although it fluctuates due to water regulation. This regulation maintains the lake level between 4,137 to 4,143 feet above sea level to protect the fishery and downstream coho salmon habitats.

Ecological and Geological Significance

Upper Klamath Lake is the remnant of the ancient Lake Modoc, a massive pluvial lake from the Pleistocene era. This ancestral lake once covered over 1,000 square miles, joining various lakes and wetlands into a single water body.

The lake’s environment was historically characterized by extensive marshes and wetlands, crucial for supporting a diverse range of fish, birds, and other wildlife. However, significant portions were drained for agriculture in the 20th century, impacting the habitat.

The lake is hypereutrophic, rich in nutrients, leading to frequent blue-green algae blooms, particularly Aphanizomenon flos-aquae. These blooms, exacerbated by agricultural runoff, reduce water clarity and recreational use during summer, posing challenges to the lake’s fish populations and overall ecological health.

Wildlife and Conservation Efforts

Upper Klamath Lake is a critical habitat for several fish species, including the endangered Lost River and shortnose suckers. In response to their dwindling numbers, the U.S. Fish and Wildlife Service has taken significant conservation measures, including listing these species as endangered and monitoring the lake’s water quality.

The lake is also an essential stopover for waterfowl on the Pacific Flyway and is renowned for its rainbow trout fishery, attracting anglers from far and wide.

Human Impact and Ongoing Challenges

Human activities, particularly agriculture, have profoundly impacted Upper Klamath Lake. The lake’s waters are used for irrigation, supporting the Klamath Project, a century-old federal initiative for local farming. The lake level management for agricultural needs has been a point of contention, particularly during drought periods, balancing environmental concerns with agricultural demands.

In 2001, a severe drought brought these issues to the forefront, with water withdrawals for irrigation halted to protect endangered fish species, leading to significant conflict within the farming community.