You have an excellent start on pointed questions. Please continue. Effective contact with local officials, State officials, and DOT officials then becomes a wider effort perhaps aided by a forum such as this. Newspaper contributions aid in contacting the public. Perhaps even the powerboaters could be persuaded that others are negatively affected by their non-public spirited trash disposal (non) methods. If no cooperation, you could threated to get their power-boating privileges reduced because of injured manatee sightings. Schedule a big event then make a big stink that you had to cancel it.
(Wait, I don't mean it- that's talking like a lawyer). Anyway keep up the good work. Tell us how we can help.

Last night I actually got a call from a marina owner on Lake Santa Fe where many beach cats used to play years ago. HE WANTS US BACK! I felt the very earth tremble.