On the bright side, you're starting to compile accurate information!!

What is the water source for any/all of the ponds? I recall reading that the 1st fed the 2nd, and the 2nd fed the third.

The availability of water to refill any of the ponds should help educate whether or not to fully drain some or all of them.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."