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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 Comment Period Closed

The public comment period for the Mono Lake workshop has closed, effective March 24, 2023. Board staff received over 2,000 comment letters and appreciate the public's active engagement in this process. Board staff are reviewing the comments submitted and assessing next steps. To receive future notifications, please subscribe to the Mono Lake Information email subscription list, available below. For further questions, please email

  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.

Interim Diversion Limits set by Decision 1631, effective until the lake reaches 6,391 feet
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
Long-Term Diversion Limits set by Decision 1631
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 Virtual Public Workshop

February 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.

Workshop Details:

Workshop Materials:

Board staff will be accepting written comments on the workshop until 4:00 pm on March 17, 2023. Please submit written comments to

  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.

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