How do you kill river weeds with chemicals?

Emulsifiable concentrates, slow-release granules, water-soluble powders, and wettable powders are ways to kill river weeds with chemicals. The chemicals to be applied and the forms to be used depend upon whether the water body involves limited-flow waterways, large impoundments or static water. Professional landscapers often recommend copper chelates or sulfates for controlling algal weeds, diquat or fluridone for controlling such submersed plants as free-floaters and pond weeds, and glyphosate for emergents such as cattails and rooted floaters such as water lilies.