Mono Lake Basin
Mono Lake is one of the oldest lakes in North America, located at the base of the Eastern Sierra Nevada in California. Its saline environment supports a unique ecosystem and is home to a diverse collection of migratory birds and wildlife. In the early 1940s, the Los Angeles Department of Water and Power (LADWP) extended the Los Angeles Aqueduct system into the Mono Lake Basin and began diverting water from Mono Lake tributaries for use in the Los Angeles area.
The Board is invested in restoring the lake’s health and protecting its public trust values. Board staff will use this website to provide updates on potential Board actions and opportunities for input from interested parties.
Mono Lake Public Workshop on February 15
State Water Board staff will hold an informational Public Workshop on Wednesday, February 15, 2023, from 1:00-4:00 pm PST to discuss the current status of Mono Lake. The workshop will be open to remote participation only via the Zoom platform. To participate in the workshop, please visit the "Opportunities for Input" section below for details on how to register. For questions regarding the workshop, please email MonoLake@waterboards.ca.gov
Mono Lake Drought Response
The State Water Board granted the City of Los Angeles and the Los Angeles Department of Water and Power (LADWP) permits to divert water from Mono Lake tributaries. These diversions resulted in a 45-foot decline in lake level between 1941 and 1982, resulting in substantial damage to environmental and public trust resources. In 1994, the State Water Board adopted Mono Lake Basin Water Right Decision 1631 (D-1631), amending LADWP’s water rights licenses to establish establish instream flow requirements, water export limitations, and conditions to protect public trust resources in and around Mono Lake. Subsequent Orders WR 98-05 and WR 98-07 required LADWP to implement stream restoration and monitoring activities in the Mono Basin as part of a Stream Restoration and Monitoring Program.
D-1631 set a lake level target of 6,392 feet above sea level to protect the lake’s public trust resources. This target was anticipated to be reached by 2014. The decision established limits to LADWP’s exports that were intended to maintain stable lake levels once lake levels were close to the target. The decision also established interim limits while lake levels were in the process of recovering towards 6,392 feet. Ongoing drought conditions and continued exports have caused the lake to decline to a level below which significant environmental resources could be impacted. Today, exports from the lake continue to be governed by the interim limits.
|Lake Level||Diversion Volume|
|Below 6,377 feet||No Diversion Allowed|
|6,377 to 6,380 feet||4,500 acre-feet per year|
|6,380 to 6,391 feet||16,000 acre-feet per year|
|Lake Level||Diversion Volume|
|Below 6,388 feet||No Diversion Allowed|
|Below 6,391 feet||10,000 acre-feet per year|
|Above 6,391 feet||All available flows in excess of amounts need for fishery protection flows, up to 167,800 acre-feet per year|
- Mono Lake Fact Sheet
- December 16, 2022 – Letter from Mono Lake Committee
- December 22, 2022 - Letter from the California Indian Legal Services
- January 11, 2023 – Letter from the Los Angeles Department of Water and Power
- California Supreme Court Mono Lake Decision (1983)
- Prior Board Actions:
Mono Lake Virtual Public WorkshopFebruary 15, 2023 from 1:00-4:00 pm PST on Zoom
State Water Board staff will hold a virtual public workshop to discuss the current status of Mono Lake. The workshop will provide an opportunity to discuss current conditions and data, and will focus on Mono Lake levels in the context of severe drought and ongoing diversions from the lake's tributaries. Questions and comments will be accepted during the workshop.
Board staff will be accepting written comments on the workshop until 4:00 pm on March 17, 2023. Please submit written comments to MonoLake@waterboards.ca.gov
Mono Lake Stream Monitoring Program
On October 1, 2021, the State Water Resources Control Board (State Water Board) issued Order WR 2021-0086, approving changes and amending Los Angeles Department of Water and Power’s (LADWP) Licenses 10191 and 10192 (Applications 8042 and 8043) in the Mono Lake Basin. The new requirements aim to restore approximately 20 miles of creek and fisheries habitats in streams tributary to Mono Lake and represent a significant step forward in restoring the stream ecosystems in the Mono Basin.
The changes stem from recommendations made in 2010 by independent scientific experts (Stream Monitoring Team) tasked by the State Water Board with evaluating whether prior Board-required stream restoration flows were achieving the restoration goals of “functional and self-sustaining stream systems with healthy riparian ecosystem components” and “trout in good condition” for Rush Creek and Lee Vining Creek. The evaluation followed over a decade of studies in the creeks.
In September of 2013, following disagreement over the recommendations, LADWP, Mono Lake Committee, California Trout, and the California Department of Fish and Wildlife entered a historic settlement agreement regarding the changes recommended by the Stream Monitoring Team.
The amended water right licenses issued by Order WR 2021-0086 incorporate the provisions of the 2013 Mono Lake Basin Restoration Settlement Agreement and combine into a single document all prior terms and conditions imposed by the State Water Board in past orders and Decision 1631. Order WR 2021-0086 approves major changes to the Mono Lake Stream Restoration Program, including a requirement for LADWP to modify Grant Lake Dam by constructing an outlet structure capable of releasing the higher peak flows required in certain year-types to benefit the environment. The new Stream Ecosystem Flow regime is aimed at accelerating ecosystem recovery processes that will benefit the trout fishery and riparian habitats of Rush, Lee Vining, Walker, and Parker creeks.
- May 2009 - Effects of Flow, Reservoir Storage and Water Temperatures on Trout in Lower Rush and Lee Vining Creeks, Mono County, California
- July 2009 - Radio-Telemetry Movement Study of Brown Trout in Rush Creek
- July 31, 2009 - Pool and Habitat Studies on Rush and Lee Vining Creeks
- August 6, 2009 - Instream Flow Study Cover Letter
- August 2009 - Instream Flow Study
- September 1, 2009 - Effects of Flow, Reservoir Storage, and Water Temperatures on Trout in Lower Rush and Lee Vining Creeks, Mono County, California
- October 21, 2009 - SNTEMP Model Review Cover letter
- November 2009 - Calibration of a Water Temperature Model for Predicting Summer Water Temperatures in Rush Creek below Grant Lake Reservoir
- April 30, 2010 - Synthesis of Instream Flow Recommendations - Report | Appendices | Revised and Corrected Tables
- 2021 LADWP Compliance Report
- 2022 LADWP Compliance Report