Al,
The deepest part is 7', average is 3'. In an average year, the surface level of the pond will come down from spillway elevation 3 to 4 feet. Of course it's been a long time since we've had an average year.
The pond seemed to respond well to the trash pump aeration, but I was thinking diffuser aeration because running power to the pond will take up most of the $ I can devote to aeration but I'll do surface aeration if it is the most effective method.
Also, can you give me a tip for attaching a photo to a post? I'm not seeing the opportunity on this post page.

Thanks for your help,
fowells