The people who rent boats, at least at Maple and Tampier are independant bussinesses. I recall that the ones runnin the one at Tampier had something to do also with Reed's Canoes or Kankakee River State Park Canoe Rentals. The one at Maple also was another company. Whoever will or might rent boats at both lakes might be someone else. Remember, anyone, that there used to be boat rentals at Saganashskee Slough also? I don't know that there ever was a specific opening date for any boat or canoe rentals, even on the Kankakee. It has lots to do with the water levels and weather. Sorry, that's about all I know about this. There is no exact date they open for renting watercraft.