Abstract: Qualification of the Colorado River Alluvium as a Minor Aquifer in Texas

Geoffrey P. Saunders

The Colorado River Alluvium has characteristics which qualify it for designation as a minor aquifer by the Texas Water Development Board, although the TWDB has not yet made such a designation. Without recognition as a significant water supply in the state, this resource is vulnerable to pollution and diminution.

Major and minor aquifers in Texas were redefined by the TWDB as an update to the Texas Water Plan in 1990. The Brazos River Alluvium was separated from other Quaternary deposits and designated as a minor aquifer "because of its importance as a water supply for irrigation use" (Ashworth and Flores, 1991). No other alluvial aquifers have been recognized as significant water supplies in Texas.

The Colorado River Alluvium stretches for 200 miles from Longhorn Dam in Austin to the City of Wharton. Water-bearing formations farther downstream are grouped into the Gulf Coast Aquifer. Water in the alluvial aquifer is in direct contact with the Colorado River, and has similar water quality characteristics as the river which is now considered exceptional for aquatic life. Since some communities use the alluvial aquifer for municipal water supply, it is important that groundwater is of high quality.

The Brazos River Alluvial Aquifer has been found to be highly vulnerable to pollution. Using the same assessment criteria, the Colorado River Alluvial Aquifer might also be deemed to be vulnerable to pollution.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas