WELGE-LION MOUNTAIN AQUIFER: REVISITING A MINOR AQUIFER OF THE LLANO UPLIFT AQUIFER SYSTEM, CENTRAL TEXAS

The Welge-Lion Mountain (WGLM) aquifer is an important component of the Paleozoic aquifer system in central Texas; however, it is not officially recognized as a minor aquifer by the state. This study aims to highlight its significance, particularly in the context of growing water demands and climate variability.

The WGLM aquifer was originally described in Bluntzer (1992) and comprises the Cambrian Welge and Lion Mountain formations. The Welge is a well-sorted homogeneous quartzarenite, while the Lion Mountain is a fine- to medium-grained, glauconitic green sandstone. Units represent a high-energy near-shore, shallow marine, tidal flat, and possibly locally fluvial depositional environments. The units have a combined thickness of up to 90 feet within the Llano Uplift and radiate away from the uplift into the subsurface, is faulted and segmented, similar to other Paleozoic aquifers. The WGLM is positioned above the Cambrian Hickory Sandstone aquifer, and below the Cambro-Orodovician Ellenburger-San Saba aquifer.

A query of Texas Water Development Board (TWDB) well database, combined with data from the Hill Country Underground Water Conservation District, provided data for 260 wells completed in the WGLM for livestock, domestic, and public water supply. Data show WGLM wells producing across eight counties of the Llano Uplift region, well depths ranging from 105 to 1207 feet, and well yields range from 1.5 to 150 gallons per minute (gpm)--with an average yield of 41 gpm. The WGLM aquifer exhibits excellent water quality, with total dissolved solids (TDS) between 300 and 600 mg/L.

The WLM aquifer satisfies the State’s definition of a minor aquifer because it supplies “relatively small quantities of water in large areas of the State.” Recognizing its importance as a minor aquifer among the Paleozoic Aquifers of the Llano Uplift will facilitate improved water resource planning, conservation, and management strategies.