Switching from groundwater to surface water carried by Amador Water Agency's recently finished Plymouth Pipeline is not going to be a simple matter of turning a valve.

That means a brand-new water source for Plymouth might not be flowing any time soon. Pipeline construction was finished in October.

"The pipeline is ready and able to deliver water," said Gene Mancebo, interim general manager of the water agency. "The city is working to amend its (delivery) permit. It could be a holdup for them."

A permit amendment to reflect Plymouth's switchover from a groundwater source to a surface-water source is required by the state, said consultant Richard Prima.

"Plymouth has been on groundwater for many years," Prima said. "It's fairly heavy with minerals - iron, manganese, total dissolved solids. The mineral content has coated all pipes in the city. It's established a condition in the interior of the pipes.

That means a significant mineral content of a resident's tap water is not guaranteed to disappear immediately as the first glassful is drawn from the water-agency pipeline, Prima said.

"For example, if you put distilled water into a cup (that's been used for high-mineral content water), it can leach minerals out of the container," Prima said.

The permit-amendment work will establish what Plymouth needs to do around the situation, including monitoring requirements established by the U.S. Environmental Protection Agency, according to Prima.

"It's the EPA's 'lead-and-copper rule,'" he said. "The state has to make sure we're not just not worrying about it."

David Clegern, spokesman for the state Regional Water Quality Control Board, said Tuesday the agency hasn't begun processing any Plymouth paperwork toward a permit amendment.