Boaters on their way to local lakes to take advantage of Saturday's nice weather were surprised by mandatory boat inspections in north Spokane County.
Washington Fish and Wildlife officers set up a checking station on Newport Highway, looking for boats carrying Zebra and Quagga Mussels.
Officials are desperate to keep them our of our lakes and streams.
"We're trying to protect it. Its epidemic in the Midwest," said Mike Whorten, with Washington Fish and Wildlife.
The mussels attach to propellers and hulls. Unsuspecting boaters then transfer them From lake to lake, clogging pipes, dams, and ruining the ecosystems.
"They've clogged water treatment plants and sterilized lakes for aquatic life," said Whorten.
Fish and Game officials say Washington lakes are free from the mussels, but there have been some close calls. Just last summer, law enforcement officials stopped and confiscated a boat loaded with the mussels heading for Washington lakes.
"Once they're here they're impossible to stop or reverse," said Whorten.
About 75 boats were checked on Saturday, all free of mussels, something that doesn't disappoint inspectors.
"We don't want to find anything," Whorten said.