[Descant]

Back to the original post and headline.
2, 4-D is not just dumped into the lake. Improper concentration is ineffective. Unfortunately almost any product can be misused, so there is a huge difference between a certified, DES monitored application, and your neighbor buying something and just throwing it off the end of the dock. Yes, people do that.

The time frames, e g. don't swim for three days, are basically the time it takes for a follow up water test to get a "non-detect" reading. I don't know of any instances where water was ingested prematurely causing illness, but there is no reason not to be cautious.

For the misconceptions about Agent Orange, I asked Amy Smagula, DES Limnologist, to clarify:
"In short, Agent Orange was a product that was used as a defoliant in the Vietnam War era. The name came from the fact that the chemical mix was stored in blue barrels with an orange stripe. Agent orange was a mix of two products, 2,4-D and 2,4,5-T. In the making of the 2,4,5-T, a byproduct was formed, which was a dioxin, known to cause cancer and other disorders. That dioxin was strictly associated with 2,4,5-T, NOT 2,4-D. A lot of people don't know the history or the facts associate with Agent Orange, and thus there are a lot of misconceptions about it. Simply put, 2,4-D is not Agent Orange, it was a component of it, and it was not the problem component. 2,4,5-T was the problem component, with its dioxin byproduct, and 2,4,5-T has been banned from production and use for decades."

I have been a member of the NH Exotic Aquatic Weeds and Species Committee since 2003. There have been many controlled studies over the years on various eradication and control methods for invasives like variable milfoil. The best control is prevention, like the lake host program, "Clean, drain and dry"and strong weed watcher groups who can quickly spot new plants and mark them so trained divers can remove them before they spread.