Hays Caldwell Public Utility Agency The City of San Marcos is a member of the Hays Caldwell Public Utility Agency (HCPUA). The purpose of the Agency is to resolve long-term water needs for it participants.
Edwards Aquifer Authority The City of San Marcos pumps groundwater from the Edwards Aquifer. The Edwards Aquifer Authority (EAA) manages and regulates the Aquifer.
Guadalupe-Blanco River Authority The City of San Marcos pumps surface water from Canyon Lake. These water rights are governed by the Guadalupe-Blanco River Authority (GBRA).