The Trinity Aquifer

West of the Edwards outcrop the country drinks from a different aquifer. The Hill Country Trinity is a stack of older Cretaceous sands and limestones, and unlike the Edwards it neither takes water quickly nor gives it back in great springs. It fills slowly, through fractures and thin soil, and a well drilled into it produces modestly and recovers slowly. Almost every house, ranch and small water system between Dripping Springs and Johnson City sits on it. That is why this stretch of road carries so many water-hauling trucks in a dry year, and why the wells beside it keep getting deeper. There is no great spring anywhere along this stretch of road, and that absence is as much the aquifer's signature as any well log. The trend is not good. Water levels across the Hill Country Trinity have fallen roughly one to three feet a year over the past quarter century. In spring 2026 the Hays Trinity Groundwater Conservation District reported every one of its monitored wells sitting below historic lows, the worst reading in the district's twenty-year record. Wells that used to find water at around five hundred feet in western Hays County have been drilling past six hundred and fifty. Some new wells now go deeper still, into the confined Lower Trinity. That one is effectively a closed account. It receives almost no modern recharge, so water pumped out of it is not replaced on any timescale that matters to the people pumping it.