SACRAMENTO (CBS13) — The delta is filling up with abandoned boats and the cleanup is costly.

“Some of them are floating, some of them are sunk, some of them are partially sunk,” said Steve Hampton with California Department of Fish & Wildlife.

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The pristine waters of the Sacramento and San Joaquin Delta are supposed to be an oasis for fish, waterfowl, and recreational boating state officials say there’s now a growing danger.

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“Responding to abandoned and derelict vessels is about 20 percent of our responses,” Hampton said.

“It’s a shock,” said Steve Mayo, a coach with the River City Rowing Club, referring to when their vessels hit debris. “Our boats are low to the water, so when they hit it can be really dangerous for the kids too.”

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People leave their boats behind, many without registration numbers, and are sent to auction where they fetch next to nothing.

“There was another vessel a few years ago, the Spirit of Sacramento, it was auctioned for $1,000 and a month later we needed $3 million to respond to it,” said Hampton.

The larger commercial vessels pose the greatest danger.

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“They can leak oil, they have other hazardous materials on them, they are a threat to navigation,” he added.

It’s causing problems for the ecosystem.

So just how many boats are abandoned?

“Two-hundred-fifty is a lot and that’s just what’s in the Delta,” Hampton said.

And there may be many more underwater.

The Sacramento County Sheriff’s Department is one agency trying to clean up the mess and are having some success. Using a state grant to hire contractors, they’ve hauled off about 100 vessels in the last 10 years.

But that grant won’t pay to dispose of the larger commercial boats.

“There’s very limited funding for authority to remove these vessels, so a lot of them are just around,” Hampton said,

They’ll be around until boaters stop dumping or new laws are anchored.

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State lawmakers are working to pass a bill to address the issue. One idea is to require insurance for boaters and have stricter registration requirements..