The Edwards Aquifer in south-central Texas is the primary source of water for one of the fastest growing cities in the United States, San Antonio, and it also supplies irrigation water to thousands of farmers and livestock operators. It is also is the source water for several springs and rivers, including the two largest freshwater springs in Texas that form the San Marcos and Comal Rivers. The unique habitat afforded by these spring-fed rivers has led to the development of species that are found in no other locations on Earth. Due to the potential for variations in spring flow caused by both human and natural causes, these species are continuously at risk and have been recognized as endangered under the federal Endangered Species Act(ESA). In an effort to manage the river systems and the aquifer that controls them, the Edwards Aquifer Authority and stakeholders have developed a Habitat Conservation Plan (HCP). The HCP seeks to effectively manage the river-aquifer system to ensure the viability of the ESA-listed species in the face of drought, population growth, and other threats to the aquifer. The National Research Council was asked to assist in this process by reviewing the activities around implementing the HCP. Review of the Edwards Aquifer Habitat Conservation Plan: Report 2 reviews the progress in implementing the recommendations from the Committee's first report, seeking to clarify and provide additional support for implementation efforts where appropriate. The current report also reviews selected Applied Research projects and minimization and mitigation measures to help ensure their effectiveness in benefiting the listed species.

Aquifer storage and recovery (ASR) is a process by which water is recharged through wells to an aquifer and extracted for beneficial use at some later time from the same wells. ASR is proposed as a major water storage component in the Comprehensive Everglades Restoration Plan (CERP), developed jointly by the U.S. Army Corps of Engineers (USACE) and the South Florida Water Management District (SFWMD). The plan would use the Upper Floridan aquifer (UFA) to store as much as 1.7 billion gallons per day (gpd) (6.3 million m3/day) of excess surface water and shallow groundwater during wet periods for recovery during seasonal or longer-term dry periods, using about 333 wells. ASR represents about one-fifth of the total estimated cost of the CERP. Aquifer Storage and Recovery in the Comprehensive Everglades Restoration Plan examines pilot project from the perspective of adaptive assessment, i.e., the extent to which the pilot projects will contribute to process understanding that can improve design and implementation of restoration project components. This report is a critique of the pilot projects and related studies.

This study is an investigation of the feasibility of an aquifer storage and recovery project using the existing water supply infrastructure of the city of Millville, Utah. The project involved injecting water from a public water supply spring into a public water supply well. Geochemical analysis indicates that the major ion chemistry of the spring water is very similar to that of the principal aquifer, however, the spring water would likely cause minor geochemical changes in the groundwater due to oxidation. The study also showed that the injection well had elevated nitrate concentration which is likely due to septic systems in the area. Overall, the pilot tests showed that injection of water for storage would not be detrimental to the principal aquifer, which has significant storage abilities beyond the capacity of Millville’s water system; however elevated nitrate in the aquifer is a problem that should be addressed.