Amid a building bipartisan consensus against the plan, the State Water Resources Control Board will hold off on deciding whether to impose higher flows in three key rivers in the San Joaquin Valley to help fish.

Board chairwoman Felicia Marcus told state Natural Resources Secretary John Laird in a letter last week that the panel will not vote on the proposal to set minimum flows in the Merced, Tuolumne and Stanislaus rivers at the end of a two-day public hearing Aug. 21-22 in Sacramento.

"The agenda item ... will provide the final opportunity for comment on the staff-proposed action, but final board action on the water quality control plan update will be continued to a future board meeting," Marcus stated in the Aug. 15 letter.

Marcus cited a request from the Natural Resources Agency and the state departments of Water Resources and Fish and Wildlife for an opportunity to present during the board meeting on adaptive implementation and voluntary settlement agreements. She notes that the board has emphasized that voluntary settlement agreements would provide a faster, more durable solution to protect beneficial uses of the Lower San Joaquin River and its tributaries.

"The pending board action recognizes the importance of both flow and non-flow actions to enhance the fisheries and provides significant flexibility for adaptive implementation," Marcus writes. "Voluntary settlement agreements present the opportunity to make the non-flow elements more concrete and reduce the potential water supply impact."

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Request echoes farm groups

The agencies' request echoed those of farm groups including California Citrus Mutual and the Almond Board of California, which argued the settlement agreements and growers' water conservation efforts should be taken into consideration when considering the health of the rivers.

However, the delay also comes amid 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 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.

Related:Capitol rally to protest water agency's Bay-Delta Plan

Opposition has also been building among state legislators. Assemblyman Adam Gray, D-Merced, is holding a rally at noon today on the steps of the state capitol to protest the plan, which would require an average of 40 percent unimpaired flows along the Merced, Tuolumne, and Stanislaus rivers. The rivers are key tributaries to the San Joaquin River.

"While we are pleased with the State Board’s postponement decision, this effort is far from over," California Citrus Mutual asserted in a statement on its website. "We must remain engaged and united against this and other harmful water policies the State Board seems committed to impose on the agricultural community."

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 Sacramento-San Joaquin River 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.

Water board officials have argued that more Delta outflow in the winter and spring improves species and habitat, by increasing the number of juvenile salmon that migrate out of the Delta in the spring. Currently, flows remaining in the 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.

"The San Francisco Bay-Delta is an ecosystem in crisis," Marcus said last month in a news release. "The board's challenge is to balance multiple valuable uses of water -- for fish and wildlife, agriculture, urban, recreation and other uses."

However, farm groups have argued the plan would effectively rescind water rights. In their letter, the members of Congress contend that implementation of a 40 percent minimum flow would reduce average storage in the New Melones Reservoir by 315,000 acre-feet per year while decimating deliveries to Central Valley Project contractors.

The Water Board hearing itself will begin at 9:30 a.m. Aug. 21 and 22 in the Coastal Hearing Room of the California Environmental Protection Agency headquarters building, 1001 I St., Sacramento. The hearing will be broadcast online.

For information about the hearing and the proposal, visit https://www.waterboards.ca.gov/