Edwards-Trinity (High Plains) Aquiferinteractive map | cross-section

Summary

The Edwards-Trinity (High Plains) Aquifer is a minor aquifer that underlies about 9,000 square miles of the Ogallala Aquifer in western Texas and eastern New Mexico. Its water-producing units include sandstone of the Antlers Formation (Trinity Group) and limestone of the overlying Comanche Peak and Edwards formations. Regional groundwater flow in the aquifer is to the southeast, but locally flow is determined by the presence of Ogallala-filled paleochannels incised into the Cretaceous limestone. Recharge to the aquifer is primarily due to downward leakage from the younger Ogallala Aquifer. The greatest amount of recharge most likely occurs where low-permeability clay layers of the Duke Creek and Kiamichi formations, which lie between the Edwards-Trinity (High Plains) and Ogallala aquifers, are missing or thin or relatively permeable.

Groundwater typically contains more total dissolved solids than does the overlying Ogallala Aquifer. It generally is slightly saline, with total dissolved solids ranging from 1,000 to 2,000 milligrams per liter, but can range from 400 to more than 3,000 milligrams per liter. Groundwater is poorest in quality, with total dissolved solids in excess of 20,000 milligrams per liter, where the aquifer is overlain by saline lakes or the gypsum-rich Tahoka and Double Lakes formations. Freshwater saturated thickness in the aquifer averages 126 feet.

The aquifer provides water for irrigation, which uses approximately 95 percent of all groundwater that is pumped. Water level declines have occurred in some irrigated areas.

Reports