I am a complete novice when it comes to ponds but certainly do my research when it comes to real estate purchases. I can only speak for the California market since that is where I own properties.
In California a pond will definately add value as long it looks good. Even small back yard koi ponds add value here (granted only a small amount but some value is added). The key, in my opinion, is that the pond should look as good as possible (clean & clear), it should look as natural as possible and is a real plus if it can be viewed from the house.
People (at least in the California market) like properties with some unique quality about them. Something to escape the ordinary and set their property apart from the neighbors. A view is always a plus. I have owned golf course homes and beach homes and the problem with those views is that you cannot control the view environment. Neighbors can plant trees that block your view, homes can be built that block the view, etc, etc.
IMHO, the one advantage of having your own pond is that if the property is designed well, the pond can be both a great recreation feature and a great view feature. And can be one that the property owner controls (for better or worse).
How much value does it add, who knows. But if the pond looks good and the overall property is well thought out I think that you will command among the highest price in the market at the time. A think the "other side" to the coin is that if the pond looks bad and/or is poorly designed then it can become a liability when it comes time to sell.
Anyway that's my two cents worth.
Which reminds me of a joke... If someone offers you a penny for your thoughts and you give them your two cents worth, does the IRS get the other penny?
Sorry, just some CPA humor, I'll go back to my cage now.
