Justin,

I think the best thing for you to do is talk to your county agent and find out your rainfall and evaportation rates for your area. This will be a good starting point to answering your question.

Since your weather has been unusually dry in the last few years, it may simply be a weather/soil combination issue. Too little rain, too dry soil.

This is such a hard question to answer without more history on the pond or knowing the soil type.