I need to correct myself a bit. Some pine trees do have deeper roots, but most are not as bad as hardwood trees. It's the famous "it depends" per species.
Other thoughts....
It may pay to find out from the proper authorities if you would be allowed to renovate the pond. You may find out that it is now protected or regulated. Your probably ok, but worth looking into if renovation is a deal breaker to buy or not.
A lot of folks here say that renovation costs just as much as building a new pond. That can go one way or another depending on what is needed. However, you can enjoy the pond "as is" till the rest of your life settles down a bit, and then improve it when you can have more time/cash. Find out what that depth is, thats the first concern if it will keep fish and if it needs immediate renovation. The dam would be the next on the renovation list. If its deep enough, you could get by for "x" number of years till that dam needs work.
Knowing the depth of the pond will also tell you if you could siphon-drain it without cutting thru the dam to drain it. Is the pond bottom higher than the backside of the dam where it drains?
How about getting a pond builder out there right now to give you a ballpark idea of what a full renovation may cost? Might use that as a bargaining chip also....
