The Santa Clara Valley Water District board of directors on Tuesday ordered an immediate halt to boating on South Bay reservoirs.

The four-to-three vote was aimed at keeping the potentially damaging quagga mussel out of the county water system.

The tiny mussel can reproduce in such large numbers that it can clog pipes, valves and pumps.

The creature is known to hitch-hike between bodies of water such as lakes and reservoirs on boat hulls and engines. The ban will run until the start of the Memorial Day weekend on May 23rd; that's when the water district plans to have a boat inspection plan in place.

Santa Clara County spokeswoman Gwendolyn Mitchell says boat owners will have to pay a seven dollar fee for the inspection, in an effort to offset the estimated half-million dollar cost of the inspections.

The quagga mussel is native to Russia and is thought to have arrived in the United States in the ballast water of commercial ships. They have caused millions of dollars of damage in the Great Lakes region.

The mussels arrived in california last year and were spotted in San Benito County in January.