Toxic chemicals have already been found in McClelland Lake, just southeast of the park. Locals stopped taking their drinking water from the lake years ago.
"The death of this ecosystem means nothing to me, fool! Only more beaver lebensraum!" - Berb, the beaver.
Okay, I'm joking with the above. Serious now: AFAIK beavers, corals and humans are the only clades who are able to perform such deep changes in the geography of the environment around them. After doing some maths, "17 acres" (I'm not used to this unit) would be roughly 70 000 m²; that's a fucking lot specially considering how smaller they are in comparison with us.