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Mono Lake Basin

  Announcements

Notice Requesting New Mono Lake Information
State Water Board staff will hold one or more public workshops and meetings in 2026 to collect information on the condition of Mono Basin's public trust resources and evaluate potential management options. The workshop(s) will focus on new data that have been collected since the Board issued Water Right Decision 1631 (D-1631) in 1994. Workshop details will be posted soon.

  Mono Lake Management Level and Diversion Criteria

State Water Board staff will hold one or more public workshops and meetings in 2026 to collect information on the condition of Mono Basin's public trust resources and evaluate potential management options. The workshop(s) will focus on new data that have been collected since the Board issued Water Right Decision 1631 (D-1631) in 1994.

Notice Requesting New Mono Lake Information
State Water Board staff requested public input on the topics that will be covered at the workshop(s). The request was noticed on March 30, 2026 and suggested topics were due by April 13, 2026.

March 17, 2026 - Mono Lake Modeling Information Item
This item highlighted the water budget model developed by the UCLA Center for Climate Science for the Division of Water Rights, which evaluates how climate change and water diversions may affect Mono Lake water levels. Additional presentations from the Mono Lake Committee, Los Angeles Department of Water and Power, and California Department of Fish and Wildlife provided context on related modeling efforts.

Information Item Materials:

The State Water Board contracted the University of California, Los Angeles (UCLA) Center for Climate Science to develop a water budget model to better understand how climate change and surface water diversions had and will continue to impact Mono Lake. A Board Information Item was held on March 17, 2026 to provide an overview of the UCLA Mono Lake Model (MLM). The video recording of that meeting and all the presentations can be found under the 2026 Public Workshops heading.

For more information, UCLA Center for Climate Science prepared the following reports that document the model development process and key findings.

The UCLA Mono Lake Model is available by request: monolake@waterboards.ca.gov.

Please note that this model is a complex, technical tool designed for scientists, engineers, and water managers with expertise in climate and hydrologic modeling and familiarity with Mono Lake. It is not intended for use by the general public or simplified interpretation.

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 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 long-term management level 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 diversions that were intended to maintain stable lake levels once the long-term management lake level was reached. Recognizing it would take time for the lake to recover, the decision established two sets of diversion criteria. The first applies while the lake transitions to a level of 6,391 ft. The second applies once the lake reaches the transition level and moves into long-term management at a level of 6,392 ft.

Drought conditions, climate change and continued diversions have limited Mono Lake recovery, and the lake level remains below the long-term management level. Today, LADWP diversions continue to be governed by the transition limits.

Transition Diversion Limits set by Decision 1631
(effective until lake level reaches 6,391 ft)

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 Management Diversion Limits set by Decision 1631
(effective once a lake level of 6,391 ft is reached)

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 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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Contact Us

General Inquiries or Comments:

State Water Resources Control Board
monolake@waterboards.ca.gov