Got a little update from the realtor. the property owner says the riser pipe is 12 feet at the dam with the deepest parts of the pond being between 15-18 feet with the average depth being 8-10 feet.
That sounds better if you have good run-off/water-shed, but like someone said I would verify with a depth finder. Before we bought our property we had
Mike Otto come out for a consultation about the pond. It's definitely worth the money to have a
full-time professional pond building expert give a pre-purchase evaluation. It sounds like it is a unique property in your area and you really like the over-all picture...so hire an expert and use that info to verify and/or possibly negotiate a better deal on the property. Good Luck!