NewsDrop-September-October-2026

EDWARDS AQUIFER HABITAT CONSERVATION PLAN (EAHCP)

Fountain darter ( Etheostoma fonticola ): the fountain darter fish was listed as endangered on October 13, 1970. They are only found in the Comal River and the upper San Marcos River, where they depend on springflow from the Edwards Aquifer and native aquatic vegetation such as cabomba, ludwigia, sagittaria, potamogeton, hydrocotyle and more.

San Marcos gambusia ( Gambusia georgei ): the San Marcos gambusia (a one-inch-long species of mosquitofish) was previously listed as endangered on July 14, 1980. At the time, the species was already extremely rare and has not been observed in the wild since 1983. Evidence suggests that the species hybridized with the western mosquitofish, resulting in no pure San Marcos gambusia left in the wild. On October 17, 2023, the species was delisted by the USFWS due to extinction. Peck’s cave amphipod ( Stygobromus pecki ): the Peck’s cave amphipod was listed as endangered on December 18, 1997. This crustacean lives within the Edwards Aquifer and in the Comal Springs. They use their five pairs of legs to swim quickly and burrow in sediment. A common misconception is that the Peck’s cave amphipod is named after a cave. In fact, it was named after Stewart B. Peck, who collected the first known specimen. Comal Springs riffle beetle ( Heterelmis comalensis ): the Comal Springs riffle beetle was listed as endangered on December 18, 1997. They live near spring orifices in the surface water of the Comal and San Marcos springs. Although they possess hind wings, they are small and nonfunctional, rendering the beetle incapable of flight. Compared to the dryopid beetle, the riffle beetle is more vulnerable in low springflow conditions.

By: Mikaela Garcia EAHCP Intern for Threatened and Endangered Species

The Covered Species of the EAHCP

The EAHCP covers 11 species, including three salamanders, three insects, two fish, two crustaceans, and one aquatic plant. Since the EAHCP began in 2013, some Covered Species (specific threatened or endangered plant or animal that is explicitly protected under the EAHCP) have undergone changes in listing status or taxonomy; these updates are summarized here, along with a brief overview of each Covered Species.

The Edwards Aquifer Habitat Conservation Plan (EAHCP) is a regional program that protects aquatic habitat for endangered species in the Comal and San Marcos springs systems while ensuring the sustainable, long-term use of the Edwards Aquifer for South Central Texans.

Fountain darters , like all darter fish, lack a swim bladder so they cannot float; instead, they hop and dart along the bottom of the river. Aquatic vegetation is important for this species to protect them from larger, predatory fish, and it also provides habitat for their food source, or smaller organisms. Habitat restoration has focused on native aquatic plants that can also survive as emergent during extreme low-flow conditions. Fountain darters are an indicator species (that is, if their populations begin to significantly decline, it is a direct indicator to water managers that the aquifer’s water levels or quality might be dropping to dangerous levels) for both the Comal and the upper San Marcos rivers since they have a larger range, and we know more about their life cycle and habitat needs than the other Covered Species. Comal Springs dryopid beetle ( Stygoparnus comalensis ): the Comal Springs dryopid beetle was listed as endangered on December 18, 1997. This beetle is fully aquatic, living both within the subterranean caves of the Edwards Aquifer, within and near the Comal Springs orifices, and they have been occasionally detected in the San Marcos Springs system. To breath underwater they use a thin layer of trapped air called a plastron, which allows them to extract dissolved oxygen from the water. Edwards Aquifer diving beetle ( Haideoporus texanus ): the Edwards Aquifer diving beetle was petitioned for USFWS listing as endangered or threatened on June 25, 2007. This insect is found deep within the subterranean caves of the Edwards Aquifer and has been expelled through artesian wells and springs. They lack wings and eyes, but they use their long bodies to navigate pore spaces and gravel beds within the aquifer. On June 17, 2025, the USFWS determined that listing the species was not warranted, largely because their deep aquifer habitat makes them resilient to drought conditions. Texas troglobitic water slater ( Lirceolus smithii) : the Texas troglobitic water slater was petitioned for listing on June 25, 2007. This crustacean is found within the subterranean caves of the Edwards Aquifer. They have been observed at three artesian wells and springs located within just 600 meters of one another, suggesting that the species occupies a relatively small area of the aquifer near the freshwater-saline boundary. On November 29, 2023, the USFWS found that the species is not warranted for listing as endangered or threatened, because of its likely high rate of reproduction and resiliency to drought conditions.

San Marcos salamander ( Eurycea nana ): the San Marcos salamander is the only federally threatened species covered by the EAHCP, listed on July 14, 1980. These salamanders are highly adapted to stable temperatures and springflows found primarily in the San Marcos Springs. Similar to other aquatic salamander species, the San Marcos salamander does not go through metamorphosis and retains its external gills throughout its life. It lives underneath and between the rocky, cobble substrate.

Texas wild-rice ( Zizania texana ) : Texas wild-rice was one of the first plants to be listed as endangered and covered by the federal Endangered Species Act (ESA) on April 26, 1978. It is only found in the upper San Marcos River and depends on steady springflow for growth and survival. In 2012, the upper San Marcos River was designated a State Scientific Area, making it illegal to uproot or intentionally disturb Texas wild-rice and other protected flora and fauna in the river. Under the EAHCP, the areal coverage of Texas wild-rice has increased from 4,561 m 2 in 2013 to 12,586 m² in 2025.

Despite status and/or taxonomy changes, all 11 species will remain as-is on the current Incidental Take Permit until it expires in 2028. This permit acknowledges that while everyday, otherwise lawful activities (like drawing water from the aquifer for human use) might inadvertently harm or disturb (“take”) these species or their habitats, the activities are legally allowed to continue. Moving forward, the next 30-year Incidental Take Permit will not cover current species that have been declared by the U.S. Fish and Wildlife Service (USFWS) as extinct or not warranted for listing, including: San Marcos gambusia, Comal Springs salamander, Texas troglobitic water slater, and Edwards Aquifer diving beetle. Texas blind salamander ( Eurycea rathbuni ): the Texas blind salamander was listed as endangered on March 11, 1967. This species of salamander lives underground in the Edwards Aquifer in the San Marcos area. Adapted to the dark caves of the aquifer, they lack eyes and locate potential prey by using sensitive skin cells called neuromasts that can detect waves created by the prey’s movement through the water. In 2021, the USFWS officially updated the scientific name from Typhlomolge rathbuni t o Eurycea rathbuni. Fun fact: Texas blind salamanders, and other salamanders, can regrow limbs like their tails and fingers if there is a clean cut in the severed or injured area.

Comal Springs salamander ( Eurycea sp. ): the Comal Springs salamander was petitioned for USFWS listing as endangered or threatened on June 18, 2007; however, the petition was withdrawn on April 8, 2020. Classification of this salamander has been debated, and studies have shown that it may be a population of the Blanco Springs salamander ( Eurycea pterophila ), also called Fern Bank salamander, or Texas salamander ( Eurycea neotenes ). Found in the Comal Springs, this salamander relies on stable springflow and constant temperatures. They live in cobble or rocky substrate and prey on small invertebrates.

Scan the QR code to view an interactive map of Texas wild-rice coverage from 2013 to the most recent available coverage, 2025.

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