BOISE -- Tens of thousands of boat inspections later, Idaho and Washington have come through another boating season without getting invasive quagga or zebra mussels established in either state's waters, but there were plenty of close calls.

Idaho intercepted 24 mussel-contaminated boats entering the state, and Washington decontaminated 20. Most were coming from the heavily infested Great Lakes region; the rest came from federal waters in Arizona and Nevada. That has officials in Washington and Idaho concerned.

"Mussel-fouled boats continue to leave infested waters without proper decontamination," said Idaho Department of Agriculture Director Celia Gould. "The federal government needs to do a better job of containing infestations in their waters and preventing the spread of these species to the Pacific Northwest states."

Lake Mead, Lake Havasu and other federal waters in the lower Colorado River system are contaminated with the tiny, invasive mussels that multiply so quickly they can encrust and ruin beaches, pipes, equipment and more.

Washington, Idaho, Utah, Wyoming and Montana have sent letters for three years to the National Park Service, which runs the Lake Mead National Recreation Area, appealing for help.

The park service at Lake Mead is now sending notifications to invasive species programs when there are boats bound for their states. Idaho invasive species coordinator Amy Ferriter, however, said, "We inspected 65 boats from Lake Mead this season, and we only got a handful of notifications. So we're still working on it, but we could definitely use some help from down south."

John Wullschleger, fisheries program leader for the National Park Service, said he believes Lake Mead is the only contaminated water that's trying to decontaminate boats.

"I'm aware that it's not always successful," he added.

Part of the problem is that "it's not clear what our authority is with boats that are leaving the park area," Wullschleger said. "We do have a lot of authority over boats coming in, but once they go, it's not real clear."

So the parks service has focused on concessionaires who operate marinas, asking them to distribute and collect inspection forms and pass them on to state officials. Working through concessionaires helps avoid privacy restrictions that bar federal officials from distributing such information.