Therefore, lake shoreline property owners and pond owners must obtain a permit to apply chemicals to their lake or pond. Chemicals have been used with varying success. Dosage rates must be carefully calculated and the chemicals must be applied properly. The old adage, if one is good, two is better does not apply. Some lakes and most rivers are poor candidates for herbicide or algicide treatment because of strong currents or outflows that can cause pesticide drift.
Many aquatic pesticides restrict certain water uses such as swimming, fishing or watering lawns.
Aquatic plants also differ considerably in their susceptibility to chemical treatment. No chemical will eliminate all plants no matter how broad-acting it may be. Chemicals only kill plants they contact and usually do not affect next year's plants. For example, 2,4-D will only control a limited number of aquatic plants classified as dicotyledons. Prior to purchasing chemicals or chemical application services, consider other methods that will do the job.