SACRAMENTO (CBS/AP) — Gov. Jerry Brown is rethinking a major component of the state’s proposed $25 billion twin-tunnel water project.

The San Jose Mercury News reports that the governor is proposing to dropa 50-year guarantee to restore the environment in the Sacramento-San Joaquin Delta as part of the twin-tunnel plan.

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The project is intended to restore salmon and other endangered species to the delta.

The change comes after biologists at the U.S. Fish and Wildlife Service and other federal agenciestold the state they won’t issue permits for the environmental plan because the state cannot prove it will restore salmon, smelt and other wildlife.

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The newspaper says the change could make it harder for Brown to win backing for the project.

The tunnels are designed to send water around the Delta to Central Valley farms and Southern California cities.

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