Tom, we used Navigate for a number of years on our pond to treat eurasian milfoil. It worked quite well on the milfoil in lower doses. One thing that happened was that over time the coontail became the the dominant weed in the pond, the Navigate did not work well on coontail in low doses. Right now we are using Reward/Cutrine Plus/Surfactant that works extremely well on both types of weeds.