The objective of this study is to identify major sand trends, which, along with subsurface temperatures and pressures, aid in evaluating the potential of producing geothermal energy from the Frio Formation, Upper Texas Gulf Coast.

Geologic map that depicts the surface geology of Loving, Crane, and Ward Counties and parts of Ector, Midland, Upton, Pecos, Reeves, Crockett, and Winkler Counties, Texas. The 5-page booklet indicates geologic formations, abbreviations, and ages.

Geologic map that depicts surface geology of Starr, Hidalgo, Willacy, and Cameron Counties and parts of Zapata, Jim Hogg, Brooks, and Kenedy Counties.

Disposal and temporary surface storage of spent geothermal fluids and surface subsidence and faulting are the major environmental problems that could arise from geopressured geothermal water production. Geopressured geothermal fluids are moderately to highly saline (8,000 to 72,000 parts per million total dissolved solids) and may contain significant amounts of boron (19 to 42 parts per million). Disposal of hot saline geothermal water in subsurface saline aquifers will present the least hazard to the environment.

Historical monitoring along Matagorda Island and San Jose Island records the nature and magnitude of changes in position of the shoreline and vegetation line and provides insight into the factors affecting those changes.