A massive plan to build new plumbing in the Sacramento-San Joaquin Delta, California's most important water supply, began trickling out Thursday as state officials released hundreds of pages of draft documents.

Known as the Bay Delta Conservation Plan, the major features of the proposal are two giant tunnels to divert the Sacramento River underneath the estuary, and three new intakes along the river in Sacramento County. In addition, 145,000 acres of habitat would be restored to benefit 57 imperiled wildlife species, including chinook salmon and Delta smelt.

The documents released Thursday are considered preliminary drafts, and offer a preview of a formal draft expected in July that will be subject to scrutiny by state and federal wildlife officials under their respective endangered species acts.

"We're doing this now so the public can begin to digest the plan," said Mark Cowin, director of the California Department of Water Resources, the agency leading the project. "This plan isn't about waging war. It's about resolving some of the most critical resource conflicts in California."

Still, it was an important first look at a major water plan. West San Joaquin Valley farmers who rely on Delta water deliveries see the latest announcement as a good sign. They want changes in delta operations that this year have left them with a water forecast of only 25%.

Dan Nelson, executive director of the San Luis & Delta-Mendota Water Authority, represents farmers working 1.2 million acres, half of which are in Westlands Water District. He has been critical of pumping cutbacks to protect dwindling fish species, such as the delta smelt.

"California's water supply system is broken," he said. "Science has shown us that a comprehensive plan is essential to meet the future needs of our cities, farms, and wetlands."

Water from the Delta serves 25 million Californians and 3 million acres of farmland from San Jose to San Diego. The goal of the twin tunnels, which would cost an estimated $14 billion, is to protect that water supply from floods, earthquakes and sea-level rise. It would be funded largely by higher water rates charged in the communities that receive the water.

In addition, it is hoped that the new diversions would better protect native fish species including the delta smelt currently killed by the millions in decades-old state and federal diversion pumps located in the south Delta near Tracy. Those powerful pumps reduce natural flow patterns in the estuary, confusing fish and disrupting habitat. The new diversions would avoid that problem by drawing directly from the Sacramento River near Clarksburg, and would also have modern fish screens to exclude fish swimming nearby.

Read the first four chapters of the BDCP draft.

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