As for chemicals, again, if the chemicals are legal, and legally applied to use in pond A, and they harm pond B. The owner of pond B accepted all risk of what may flow in....
Because a chemical is legal doesn't mean it has really been tested to be safe even when used according to the label. Two experiences I have had.
When coming home and getting out of my car I was overpowered by a strange smell and couldn't get my breath, thinking I was going to suffocate. I went into the house and could breath. I then went outside on my upper deck to see if what I had just experienced was still there and again couldn't breath. I stayed in the house for sometime until the air cleared. I told my farmer about it and he said he experienced the same thing and quite using the chemical. I had no idea it was spray from my farm.
I was a pattern maker as my occupation. About 20 of us in a large building were at work and we started to use a new epoxy for radius's on the patterns. Within an hour our faces and fingers started to go numb and we cleared the building. That's the reason I don't trust legal chemicals as some do. I could site other incidences of legal chemicals gone bad.
What is safe, or isn't, is really a matter of opinion. for any herbicide to be marketed in the USA, it must include an EPA approval/registration number. I'm thinking the EPA only begrudgingly gives those out after trying to find any way to deny approval...
To achieve EPA registration, aquatic herbicides must be effective in controlling target weeds, and also meet the rigid environmental and toxicology criteria required by the EPA. Aquatic herbicides require testing over and above that needed for non-aquatic herbicides, and take many years of research before a new aquatic herbicide can be approved by the EPA. Data from nearly 150 tests must be submitted and evaluated, including toxicity, environmental persistence and other factors.
