Merced River, Yosemite Valley, Oct. 2022 / Dead Lower Merced River Aug. 2022
The Merced River, the iconic wild and scenic river flowing out of Yosemite National Park, died in the summer of 2022 upstream of its confluence with the San Joaquin River. The river was completely dewatered from July 7 to October 7.
It was dead for 3 months over a nearly 5-mile stretch. It could not offer fishing, swimming or any other water-based recreation in the hot summer months. In the early fall, the Chinook salmon were unable to migrate on schedule to the Merced to spawn, and total fish return numbers for the year were dismal. Their migratory route, the river, had been transformed into a dry wash used as a raceway for off-highway vehicles.
This wasn’t the first time the Merced River died, but hopefully it will be the last time. The California State Water Resources Control Board (State Water Board or Board) must do its job and take action now to ensure year-round minimum flows for the river.
On January 8, 2024, CSPA joined Friends of the River in sending a joint letter to the State Water Board urging it to adopt permanent minimum flow regulations on the Merced River to prevent this disaster from ever happening again. Our letter was in support of letters that the National Marine Fisheries Service (NMFS) and the California Department of Fish and Wildlife (CDFW) sent to the Board in the fall of 2022 and spring of 2023.
These letters alerted the Water Board of the severity of the dewatering and included the following key points:
- Requiring flows for only a portion of the year is not adequate. (Note: The approved 2018 Bay-Delta Plan Amendment only has required minimum flows from Feb. – June, none for the hot, dry months of summary/fall. In addition, the Plan has yet to be implemented). Year-round flows are needed to assure base flows over the dry season. NMFS recommended interim base flows in the lower river derived from the California Environmental Flows Framework (CEFF) until future studies can refine necessary flows.
- Permanent minimum flows in the Merced River are needed to provide a migration corridor for federally-listed Central Valley steelhead and for spring-run and fall-run Chinook salmon. The Merced River needs to be connected to the San Joaquin River with enough water depth for fish to pass upstream to the spawning grounds.
- The Board should immediately expand necessary monitoring, evaluation,
and reporting of water diversions to ensure compliance with existing water rights in the Merced River watershed. - The Basin Plan for Sacramento and San Joaquin River Basins identifies the beneficial uses of the Merced River from McSwain Reservoir to the San Joaquin River as: recreation, including fishing, canoeing and rafting; warm and cold freshwater habitat; migration; spawning; and wildlife habitat. All these beneficial uses require flowing water in the stream.
- Flows at the confluence of the Merced River are essential for an overall functioning ecosystem and riparian habitat in this major watershed.
In response to these letters, Board staff met with NMFS and CDFW staff for a discussion in early 2023. So far, the Board has yet to propose any solutions.
On December 5, 2022, Merced Irrigation District (Merced ID) submitted a letter to the Board in response to NMFS’s October 27, 2022 letter. Merced ID outlined its compliance with its regulatory flow requirements at compliance points on the river. It found “flow losses in the lower river downstream” from Shaffer Bridge. Merced ID also wrote it is aware that a number of unauthorized and unpermitted diversions have contributed to reduced flows and drier river conditions downstream of Merced ID’s diversions and in the areas described in NMFS’s letter. Merced ID wrote that it has repeatedly requested that the State Board take action to regulate and limit those unauthorized diversions, including appointing Merced ID as watermaster for the lower river. Merced ID requested that the Board take charge of investigating possible illegal diversions.
Another example of the Board’s failure to take action is illustrated in a 2016 water rights complaint made by the Stevinson Water District (SWD), which is located at and around the confluence of the Merced and San Joaquin Rivers. SWD wrote that the Merced was “a practically dead river,” and that flows were zero at Stevinson according to the CDEC water gauge. The letter requested immediate investigation of unlawful diversions. The Board’s much-delayed response, after a five year wait, was a letter dated July 23, 2021. The Board stated, “During the previous drought the Division’s resources were overwhelmed, and we were unable to process your complaint. It is impractical for staff now to investigate alleged violations from the previous drought… For this reason, the Division [of Water Rights] is exercising discretion and will take no further action on this complaint.”
CSPA agrees that there is a need for more robust monitoring of any and all diversions on the lower Merced River. The issue does not stop at unauthorized diversions. The State Water Board must also prevent authorized diversions from cumulatively drying up the river. It is well-settled law that “no party can acquire a vested right to appropriate water in a manner harmful to public trust interests and the state has ‘an affirmative duty’ to take the public trust into account in regulating water use by protecting public trust uses whenever feasible.” (Light vs. State Water Board). It is also well-settled law that “no one can have a protectible interest in the unreasonable use of water.” Id.
Several mechanisms come to mind. A responsible entity is one: to shut down unauthorized diversions, to curtail diversions in order of priority, and to limit riparian diversions to natural flow and the flows released by Merced ID to meet the adjudicated Cowell Agreement. Another potential mechanism is the water quality certification for the Merced River Project relicensing: requiring enough flow at Shaffer Bridge to keep the river watered to the confluence with the San Joaquin. The flows required by the Federal Energy Regulatory Commission aren’t doing the job now, and as proposed, likely won’t do the job under a new FERC license either.
CSPA urges the State Water Board take action now to prevent future dewatering. It remains an unaddressed, unregulated, and unenforced problem. With no consequences or enforcement during past dewatering events, it was no surprise the dewatering occurred again during California’s latest extended drought. The lower Merced River needs permanent protections requiring year-round base flows as well as enforcement of water rights.
Further Background:
The New York Times published an article on January 18, 2023 about the Merced River dewatering which called into question the State Water Board’s ability to manage water supplies.
For additional photos, maps, flow data, and salmon return information about the Merced River dewatering in 2022, go to the California Department of Fish & Game’s Case Study: Lower Merced River Disconnect:
The California Data Exchange water gage at Stevinson on the Merced River near the confluence with the San Joaquin River provides current and historical flow information.