Hi Dave Ott,
I contacted the natl EPA, and the local Michigan Dept. of Environmental Quality. He said that, "its a gray area in the regulations." Using chems to clean a dock over water w/ chems would not be recommend. Cleaning the dock with high water pressure would be recommend he said. And also, using a brush/roller to paint instead of spraying would be better on the dock so as to minimize the paint discharge to water.
thanks for you response,
Ramie