Sonar A.S. Liquid 

Sonar Liquid with fluridone is a systemic herbicide for controlling weeds in fresh water ponds, lakes, reservoirs, irrigation canals and drainage ditches. Provides excellent control of many difficult to control weeds. For best results, apply Sonar Liquid in spring and summer during the early stages of growth.More - http://www.killlakeweeds.com/products/sonar-a-s