Isn't 2,4-D used right in ponds? DO numbers should help. Hot day
Depends on the formulation, some formulations are toxic to fish, if I found the right label the one they sprayed is toxic to fish. A one - two punch, toxicity and a DO sag, and it may volatilize during hot weather.
http://www.cdms.net/LDat/ld2DI004.pdf
