I suppose if the body of water is really full of detergent, you might begin to slow the growth of the Common Water Hyacinth. It's a pretty resistant plant, however. You should try Goggle for more info, limiting your search selections to the sites that appear to be close to your application type -- power-plant cooling lake, with limited other living things, or commercial waterways, which need to have careful dosage, to avoid killing other living things, or ... what? We're a wide group here, pretty smart, with diverse backgrounds, but you're not going to find the solution to a major ecological issue with a forum posting.