For a 1/8 acre pond and a well, you can fill it with 40 gallons per minute in less than a week. So, you don't necessarily need a watershed. If that's the case, think about raising your pond above the floodplain with a levee...if that makes sense. Then, you are immune from flooding. But, with a 1/8 acre pond, it's not hard to start it over after a flood. The main loss will be time spent to get it where it is before the flood.

To answer your question, yes, start with a water chemistry analysis of the well. We send ours to Texas A&M's soil sciences lab. Plenty of parameters checked, for $25 per sample.

soiltesting.tamu.edu/files/waterweb1.pdf


Teach a man to grow fish...
He can teach to catch fish...