The southern valley aquifer is unconfined and geographically restricted to a narrow, strip-like setting, and is relatively shallow (ca. 100 ft average saturated thickness).
At least two-thirds of recharge to the southern aquifer originates in the Bannock Range, most likely from the Mink Creek and Gibson Jack watersheds.
Possibly in excess of 90% of the ground water flowing through the southern valley supplies all of Pocatello's and Chubbuck's municipal wells.
The southern valley aquifer sustains most of the municipal drinking water system and there is little room left in the southern aquifer from which to extract clean drinking water.
The predicted capture zone for new production Well 44 could extend substantially west of the Portneuf River, potentially capable of drawing TCE plume contamination over to the east side of the aquifer, and thereby threatening to spread TCE over a larger area of the aquifer (Appendix 3).
The hydraulic effect of the pumping-and-injection wells proposed at the LDS ballfield would be to offset some of the capture effect of Well 44 (by injecting clean, treated water that would be drawn over to Well 44), but their effectiveness in doing so cannot be accurately predicted without better knowledge of the temporal variability of the plume's width, the spatial variability of aquifer permeability, the areas in which most of the recharge occurs, and the actual hydraulic effect of the river.