"I guess its just going back to where it came from." NO! Please, please, DON'T pump well water out onto the ground with no purpose! Well water, paleolithic water, has taken a LONG time to get where it is (thousands of years). (paleo="old" lithic="rock"). Additionally, unless you're testing both the ground water (from the stream), and the well water, I would bet money that they're not the same. Here in Central Oklahoma, we have two sources of water in the cities, lake (or reservoir) water and well water. Twice a year, the lake-sources water (and it's *very* obvious where it comes from) tastes really nasty (like muddy fish) because the lakes "turn over" in Spring and Fall due to changing temperature. Well water is no solution either. We sit on top of the Garber-Wellington Aquifer, a bountiful source of water. Except that it's contaminated with arsenic and chromium from natural mineral strata the water runs through. Many of the wells the town of Norman depended on had to be shut down because the levels got too high.
https://pubs.usgs.gov/fs/2005/3111/
https://www.ci.norman.ok.us/utilities/wt/water-treatment-arsenic-study
Water doesn't just fall out of the sky! OK, well, maybe it does, but it had to go through somewhere to get to where you are. Along the way, you have no idea what its picked up (unless you frequently test...). And I'm not even going to get into the legal implications of pumping surface water from a running stream (mainly because it's a big mish-mash of federal/state/local laws).
