NewsDrop-July-August-2026

EDWARDS AQUIFER HABITAT CONSERVATION PLAN (EAHCP)

What is the Edwards Aquifer Refugia Program?

By: Kristina Tolman Senior HCP Coordinator for Threatened and Endangered Species

The Edwards Aquifer Refugia Program (EARP) contract between the Edwards Aquifer Authority (EAA) and USFWS began in January 2017. EARP operates dedicated spaces at two off-site USFWS NFHS facilities: the San Marcos Aquatic Resource Center (SMARC) in San Marcos and the Uvalde National Fish Hatchery (UNFH) in Uvalde. Both facilities use

water sourced from nearby Edwards Aquifer wells. The EAA funded a new EARP building at SMARC, completed in late 2018, and renovations to dedicated space at UNFH. The new EARP facility at SMARC includes enhanced security, a quarantine room, and redundant power and cooling systems to maintain stable conditions for the captive populations.

Refugia is derived from the Latin word refugium, meaning “shelter” or “refuge.” The term refers to places where organisms can persist through periods of unfavorable environmental change. In the Comal and San Marcos springs systems, the natural refugia during extremely low springflow conditions are the Old Channel of the Comal River and Spring Lake—the headwaters of the San Marcos River. Both areas are predicted to retain water even under severe drought. However, contamination or chemical spills could compromise these natural refugia. To guard against such events, Section 5.1.1 of the Edwards Aquifer Habitat

Conservation Plan (EAHCP) requires off-site refugia facilities to maintain back-up populations of covered species, preventing extirpation or extinction during a catastrophic event. The U.S. Fish and Wildlife Service (USFWS), within the Department of the Interior, is responsible for protecting and conserving fish, wildlife, plants, and their habitats. Through its National Fish Hatchery System (NFHS), USFWS oversees 71 NFHS facilities nationwide that raise and maintain aquatic species and plants for research and/or reintroduction of native populations.

USFWS EARP staff collect wild individuals from both spring systems and transport them to either SMARC or UNFH. Upon arrival, individuals enter quarantine, where they are assigned to aquaria by collection location and date. During quarantine, staff monitor and assess health before moving animals to primary holding spaces. In captivity, USFWS tracks feeding, reproduction, and other life-history traits. The first offspring born in captivity are designated F1. To preserve genetic diversity reflective of wild populations, only wild-caught and F1 individuals are candidates for potential reintroduction; later generations are reserved for research. Applied studies address habitat requirements, species biology, life histories, and reintroduction methods. EARP maintains wild and F1 populations of fountain darters (managed separately for the Comal and San Marcos systems), three salamander taxa (Texas blind, San Marcos, and Comal), as well as Comal Springs riffle beetles and Comal Springs dryopid beetles. EARP does not collect San Marcos gambusia because the species is extinct. The program also only maintains Texas troglobitic water slaters and Texas cave diving beetles when they are encountered in the wild, which is rare and infrequent. Texas wild-rice (TWR) plants are hand-collected within designated river reaches. Each collection is documented by location and date, and plants are maintained in raceways. Mature TWR plants are then provided to the Ecological Research Group at The Meadows Center for Water and the Environment for planting in the San Marcos River, primarily downstream of I-35.

To visit SMARC: schedule a free tour by calling 512-353-0011.

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