1-
make it required to pull plug, drain livewells and dry boat at a designated station at the exit of the launch facility where the kiosk attendant will see it. Dont let any boat leave without doing so. This could be done simply by moving the boat prep area to the exit of parking lots.

2-
Make a dip pool where each boat can back in and sterilize the hull.

3-
Study lakes that have already had this exotic species invade. Learn from them, learn how to adjust.