Chris Caskey, The Union Democrat

The Tuolumne County Water Agency released a statement Friday raising concerns about the effects the state's newly completed Bay Delta Conservation Plan will have on Central Sierra Nevada communities.

The agency joined a concert of critics who say the plan is a waste of tax dollars and a potential threat to area watersheds and long-term water supplies.

The agency argues, among other things, that the planned direct diversions of water to Central and Southern California would increase salinity in the Delta, requiring greater fresh-water releases down the American, Cosumnes, Merced, Mokelumne, Stanislaus and Tuolumne rivers.

This amounts to a "de facto" water grab from areas where the water originates - the High Sierra and Sierra Nevada foothill counties - the county argues.

"Draining uphill reservoirs and impacting our rivers, including those designated as Wild and Scenic, would decimate our tourism and recreation industries, seriously undermine the Sierra Ecosystems and severely impact our local consumptive water supplies," the county agency said in its statement.

The $24.7 billion Bay Delta plan was launched to protect the sprawling Sacramento-San Joaquin Delta - the largest West Coast bird estuary, an important route for migratory fish, and one of the nation's most productive farming regions - while improving water supply for millions of Californians who rely on water pumped out of the delta.

At the heart of the 50-year plan, unveiled last summer by Gov. Jerry Brown, are twin tunnels with a 9,000-cubic-feet-per-second capacity. The tunnels would replace the delta's current pumping system which endangers fish and other wildlife.

State water officials argue creating an alternative delivery method from the pumps - and restoring more than 100,000 acres of new habitat above ground - will help the fish rebound and keep the water flowing to cities and San Joaquin Valley farms.

The plan, and its associated environmental impact studies, were released last week by the state after seven years of study, and includes proposals for building the tunnels and completing significant habitat restoration work. The release kicks off a 120-day public comment period.

Tuolumne County isn't the only local agency critical of the plan.

The Tuolumne Utilities District and Calaveras County Water District argue the plan is too costly and will do even more harm to the ecosystem.

They're concerned the Tuolumne and Stanislaus rivers will face greater water diversions to serve downstream interests.

The Associated Press contributed to this report.