The San Antonio River: Environmental Restoration Through Streamflow Augmentation

The San Antonio Water System owns and operates the nation's largest recycled water distribution system, with a capacity of 35,000 acre-feet per year. In addition to delivering recycled water to commercial and industrial customers for non-potable uses, the system is designed to improve and enhance area aquatic ecosystems through streamflow augmentation. In October 2003 the San Antonio Water System received WEF's prestigious Outstanding Achievement in Water Quality Improvement Award for the significant, lasting, and measurable improvements made in the San Antonio River and Salado Creek. What used to be a 40-mile "dead zone" in the San Antonio River has been transformed into a high quality aquatic habitat, where sensitive fish species are observed to be returning. Salado Creek is no longer listed as dissolved-oxygen impaired on the EPA's 303(d) List of Impaired and Threatened Waterbodies. The paper details the story of how San Antonio accomplished these improvements. Background on the history of recycled water use in San Antonio is provided, including the development of low-flow and low-water quality problems in area streams. An examination of how San Antonio addressed these problems follows, including discussion of infrastructure investments, changes in operational procedures, human resource development, and pretreatment programs. Recycled water system design and construction is discussed, including the modeling, sampling, and monitoring efforts that were conducted. Results of the program are presented, including conservation of potable water supplies and the return of sensitive fish species to area streams. Finally, permitting implications are discussed, along with a discussion of what the next 10 years holds for San Antonio related to continued improvements in aquatic habitats.