Marble Falls Aquiferinteractive map
- Aquifer type: unconfined
- Area of aquifer: 215 square miles
- Proportion of aquifer with groundwater conservation districts: 78 percent
- Number of counties containing the aquifer: 8
The Marble Falls Aquifer is a minor aquifer that occurs in several separated outcrops along the northern and eastern edges of the Llano Uplift in Central Texas. The subsurface extent of the aquifer is largely unknown. Water occurs in the Marble Falls Limestone in voids and fractures, and the formation is very permeable in some areas. Wells may produce up to 2,000 gallons per minute and the formation measures up to 600 feet thick with an average estimated thickness of 160 feet.
Numerous large springs originate from the Marble Falls Aquifer and provide a significant part of the baseflow to the San Saba River in McCulloch and San Saba counties and to the Colorado River in San Saba and Lampasas counties. Where underlying beds are thin or absent, the Marble Falls Aquifer may be hydraulically connected to the Ellenburger-San Saba Aquifer.
The water quality in the Marble Falls Aquifer is variable, with the total dissolved solids content increasing down-dip to the north, away from the Llano Uplift. Because the limestone beds composing this aquifer are relatively shallow, the aquifer is susceptible to pollution by surface uses and activities. For example, some wells in Blanco County have produced water with high nitrate concentrations. In the subsurface, groundwater becomes highly mineralized; however, the water produced from this aquifer is suitable for most purposes and generally contains less than 1,000 milligrams per liter of total dissolved solids.
Water from the aquifer is used for municipal, agricultural, and industrial uses.