Chet,

Ask the current land owner if he's had any problems in the past. Does he have any pictures of what the pond looks like during the peak of the season.

One of our ponds is a 2.5 acre pond that receives 100% of its water from a watershed that drains off a small dairy. That pond suffers from excessive nutrient loading, duckweed, watermeal and anaerobic activity. Not the ideal pond as far as water quality is concerned.

The level of intensity of your upstream "agricultural activity" is going to determine you water quality and the potential problems you might have.

Dig for as much information as you can before you purchase. If it seems that your "dream pond" is likely degredaded due to the upstream acitivity...keep looking for another piece of property to purchase.

My $.02 from first hand experience.