I've used the launch at Bolles Harbor nearby. (just south of there, maybe the next ramp south?) That was nice and deep. You just have to stay north of the rock wall for a few hundred yards.
When I go to sterling by boat from Toledo, the water is fine, you just can't cut too close to shore in the area of Detroit Edison. You have to go out from the park at a 90 degree angle for a while. But in general, it isn't that scary around sterling.
Hope that helps.