Stop border patrol from killing plant-life & poisoning water supply

The US border patrol will poison plant-life along the US-Mexico border (1.1 mile stretch) along the Rio Grande, so smugglers can't hide as well. For some reason the EPA deems the chemical they will use, imazapyr, safe even though it has a long half-life (a.k.a. it will hang out in the environment for a while with the water, animals, plants). So it will kill all the plants when sprayed instantly, and is likely to be distributed to neighboring areas. There is not much known about the long-term effects of the chemical. The thing is that if it works they will expand the plant murder all along the border. In a time where we are realizing the effects of pollution & chemicals on life, how can we allow this to happen? what about the people & animals that drink water there? The chemical they plan to use is imazapyr if you want to read more about it.