I think the bulk of what we are dealing with is the Milfoil, but there could be some other plants there as well.

This stuff is all up in our canal, which is about 50' wide by 3,000'. It does not seem to be all that much of an issue in the big water area. As stated, one treatment of Navigate seems to have helped, but from the appearance of it now, we did not nearly cover all the area that needed to be covered... and apparently it will need more than the one or two treatments. The first go around we mainly hit the edges of the canal, up and down each side, but it is clearly in the deeper areas (5-6' water) too.

With most of this being submerged, it is better to use a granular type weed killer, so that it is sure to get down to the roots of the plant?

Thanks!