After two postponements, the State Water Resources Control Board on Wednesday will take up a proposal to set minimum flows in three key tributaries of the lower San Joaquin River to aid imperiled fish.

Adoption of the Bay-Delta Water Quality Control Plan could require an average of 40 percent unimpaired flows in the Merced, Tuolumne and Stanislaus rivers in the winter and early spring, which water board officials have argued would improve species and habitat by increasing the number of juvenile salmon that migrate out of the Sacramento-San Joaquin River Delta in the spring.

A video broadcast of the meeting will be available here.

The board was scheduled to decide on the proposal in August but continued the hearing after representatives from the Natural Resources Agency and the state departments of Water Resources and Fish and Wildlife made presentations on adaptive implementation and voluntary settlement agreements.

The board again delayed adoption in November after Gov. Jerry Brown and Gov.-elect Gavin Newsom asked for additional time to allow for further negotiations on voluntary agreements with affected water users.

Years in the making

State water regulators have been working for several years on an update to their Bay-Delta Plan, a management blueprint for the estuary that includes the San Francisco Bay and Delta. The latest round of public comments lasted for six months and ended in March.

While Phase 1 of the updated Bay-Delta plan would affect the rivers south of the Delta, Phase 2 would involve the Sacramento River.

Currently, flows remaining in the Merced, Tuolumne and Stanislaus rivers can run as low as 10 to 20 percent of unimpaired flow at critical times of the year and range from 21 to 40 percent on average for the three tributaries south of the Delta, water board officials say.

However, farm groups such as the California Farm Bureau Federation and California Citrus Mutual have argued the plan would effectively rescind water rights, and the Almond Board of California has urged state regulators to consider efforts that farmers have already made to save water in their operations.

Mounting opposition

The plan has faced mounting opposition from President Donald Trump's administration and among federal and state lawmakers in both parties. U.S. Bureau of Reclamation commissioner Brenda Burman has threatened to sue the state water board if it devalued the federal government's investment in its water projects.

Burman's threat was backed up in an Aug. 16 letter to the board by 15 members of Congress from California -- Republicans Tom McClintock, Kevin McCarthy, Ken Calvert, Devin Nunes, Doug LaMalfa, Jeff Denham, David Valadao, Paul Cook, Mimi Walters, Duncan Hunter, Dana Rohrabacher, Ed Royce, Darrell Issa and Steve Knight and Democrat Jim Costa.

"The board's proposal clearly subordinates the beneficial human use of the water in favor of fish and wildlife measures of dubious validity, contrary to congressional authorization of the Central Valley Project and the New Melones Dam," the lawmakers wrote.

Opposition has also been building among state legislators. Assemblyman Adam Gray, D-Merced, held a rally on the steps of the state capitol in August to protest the plan.

The issue is slated as the first item to be taken up by the board on Wednesday, the second day of its two-day regular December meeting. Proceedings will begin at 9:30 a.m. in the Byron Sher Auditorium on the second floor of the Joe Serna Jr. California Environmental Protection Agency Building, 1001 I St., Sacramento.