IMHO, the well water will work fine to make the slurry. The well water running into the pond this summer will probably help with the clarity issues. Number one the well water will itself be clear and number two keeping the water level up should prevent erosion of any shoreline that is not vegetated. The one caveat is the pH of your well water. There are two major aquifers in your area, the Woodbine & Trinity, and both have high pH's..du