Depending on the herbicide used, it may take several days to weeks or several treatments during a growing season before the herbicide controls or kills treated plants. Rapid-acting herbicides like Aquathol may cause low oxygen conditions to develop as plants decompose. Low oxygen conditions may result in fish kills. Some expertise in using herbicides is necessary in order to be successful and to avoid unwanted impacts. Therefore, permits are required for certain types of herbicides.
Many people have strong feelings against using chemicals in water.
Having the public involved and educated in the treatment process is beneficial. Some local jurisdictions have policies forbidding or discouraging the use of aquatic herbicides. As policies change, control practices must adjust.