First, the disclaimer. I’m an ecosystem researcher and I’ve been working in the Nebraska SandHills for 10 or so years. The SandHills are the major recharge zone for the Ogallala (or High Plains) aquifer. That’s where water goes into the system to (hopefully) replace what we take out via wells.
The SandHills are also the largest “grass stabilized” dune field in the world, and without the grasses, they would be the largest sand dune field in the Western Hemisphere. The soils are very very sandy and porous, allowing quick and efficient infiltration of any fluids that happen to impinge upon them.
My colleague and I have just made the first measurements of the recharge rate (although only at a single point) in the region and I have a pretty good idea of how easily things can work their way down to the water table (i.e. the aquifer).