Lower Lost River TMDL

Lost River Watershed

The Lost River watershed encompasses an areas of approximately 3,000 square miles in Klamath and Lake counties in Oregon, and Modoc and Siskiyou counties in California. The Upper Lost River originates in California at the outlet of Clear Lake, and flows north into Oregon, near the Malone Dame. The Lower Lost River continues downstream of Malone Dame, flowing northwest, where it receives substantial inflow from Gerber Reservoir, and then turns westward toward the Harpold Dam. Beyond the Harpold Dam, the Lower Lost River receives inflow of Klamath River water by way of the A-Canal and Lost River Diversion Channel. The Lost River Diversion Dam can also divert water to the Klamath River.

The Lower Lost River watershed is composed of two hydrologic subareas: the Tule Lake Hydrologic Sub Area and the Mt. Dome Hydrologic Sub Area.

Impairments

Nutrients: Surface waters in the Tule Lake Hydrologic Sub Area and the Mt. Dome Hydrologic Sub Area (i.e., the Lower Lost River and its tributaries) are listed as impaired for nutrients per the 2008-2010 Section 303(d) List.

pH: Tule Lake and the Lower Klamath Lake National Wildlife Refuge, which includes the Lower Klamath Lake National Wildlife Refuge Planning Watershed and the Tule Lake Planning Watershed, are listed as impaired for high levels of pH per the 2008-2010 Section 303(d) List.

Nitrogen & Biochemical Oxygen Demand TMDLs

On December 30, 2008, the U.S. Environmental Protection Agency (EPA) established the Lost River, California, Total Maximum Daily Loads for Nitrogen and Biochemical Oxygen Demand to Address Dissolved Oxygen and pH Impairments.

• Final TMDL for Lost River, California Nutrients (PDF) (110 pp, 3.5M)
• Appendix A - Report on Lost River Model for TMDL Development, August 2005 (PDF) (234 pp, 4.8M)
• Comment Responsiveness Summary (PDF) (106 pp, 454K)

• Lost River Modeling Scenario 1D - Variable Load Reduction TMDL Except for Impoundments, 6/22/05 (PDF) (69 pp, 3M)
• Email from Mustafa Faizullabhoy of TetraTech regarding load calculations, 8/29/06 (PDF) (2 pp, 15K)

TMDL Implementation

The implementation plan for the Lower Lost River watershed is included in the Action Plan for the Klamath River Total Maximum Daily Loads Addressing Temperature, Dissolved Oxygen, Nutrient, and Microcystin Impairments in the Klamath River in California and Lost River Implementation Plan, which was approved by the U.S. EPA on December 28, 2010. The Action Plan and more information is available on the Klamath River TMDL webpage.