The following are some tips from the Great Lakes Sea Grant Network that can help prevent the spread of zebra mussels:
Always inspect your boat and boat trailer carefully before transporting. Studies have shown that transport via aquatic plant fragments is one of the major contributors to the spread of zebra mussels.
Drain all bilge waters, live wells, bait buckets and engine compartments before entering another lake. Make sure water is not trapped in your trailer. Never transport water from one lake to another.
Flush clean water (tap) through the cooling system of your motor to rinse out any larvae.
Full grown zebra mussels can be easily seen but cling stubbornly to surfaces. Boats that have been in the water for long periods of time should be carefully inspected. Carefully scrape the hull (or trailer), or use a high pressure spray (250 psi) to dislodge them. Or leave your boat out of the water for at least 5 days, preferably up to 2 weeks. The mussels will die and drop off.
In their earlier stages, attached zebra mussels may not be easily seen. Pass your hand across the boat’s bottom - if it feels grainy, it’s probably covered with mussels. Don’t take a chance; clean them off by scraping or blasting.
Dispose of the mussels in a trash barrel or other garbage container. Don’t leave them on the shore where they could be swept back into the lake or foul the area.