Thanks to everyone for the responses so far, this board is really something else!
Bill, I think you hit the nail on the head. I emailed the developer who replied that he didn't think the pond had been surveyed, and that he had found a couple spots 8-10 feet deep but he thought the average depth was closer to 5 feet. I checked up on the cost of Sonar to kill the WM and DW. Wow! Around $2000/4 acres (pond is 7 acres), and from what I've read it sounds like that might be an annual cost. I had no idea that stuff cost so much. Wow.
I think I could swing the other homeowners into a nice aeration system, but I don't think there is a chance in hell of getting everyone to support multiple thousands of dollars each year for chemicals, not to mention the manual labor involved in upkeep. I'm going to see if there are any local "pond experts" around here so I can have someone actually come to the pond and evaluate it before I make a final decision, but I'm getting the feeling that it's going to be way too costly to keep this thing looking nice. Right now I'm leaning towards selling the lot and hopefully not taking too much of a loss, and chalking it up to a "lesson learned".
I discussed all this, along with your replies, with my wife tonight, who is pretty disappointed, but understands that my happiness is important also.
Theo, I couldn't find the threads you mentioned about community controlled lakes and such.
Cary, you sound optimistic, but am I seriously looking at thousands of dollars EACH YEAR in chemicals?
sam