Interesting. Thanks for the insight "chilly". The bit about water pipes rusting out got my attention. Good science refresher too about the need for oxygen.
The water level in the pond fluctuates seasonally. Spring it's quite high. Summer it goes down as is to be expected. Fall is dependent on how much rain we get and winter is a result of what happens in the fall season. It's a fresh water pond, but I have no idea of the water's quality. It's got enough going on to support frogs and turtles, but that doesn't say much about water quality. I've seen some very nasty, algae layered, stagnant, stinky water support all sorts of life.
Unless a serial or model number is recovered from the item, I doubt we'll ever know how old it really is. Can only ballpark it. To me, it is a unique find nevertheless. Irresponsibly discarded survey equipment is a very rare find. I see more TVs and computer monitors tossed roadside than I do survey equipment. Like "Aunt Phil" insinuated, it probably had bad calibration and the owner got ticked-off with it for the umpteenth time and heaved it into the pond.
