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THE EDWARDS AQUIFER and its Unique Ecosystem – potential threats from Groundwater Management. Glenn Longley Director Edwards Aquifer Research & Data Center. Outline. Hydrologic Setting of Edwards (BFZ) Aquifer Unique Aquatic Ecosystem History of Management Current work Summary

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the edwards aquifer and its unique ecosystem potential threats from groundwater management

THE EDWARDS AQUIFER and its Unique Ecosystem – potential threats from Groundwater Management

Glenn Longley


Edwards Aquifer Research & Data Center

  • Hydrologic Setting of Edwards (BFZ) Aquifer
  • Unique Aquatic Ecosystem
  • History of Management
  • Current work
  • Summary
  • Contact information
edwards aquifer san antonio portion of fz
Edwards AquiferSan Antonio portion of FZ

Elevation near 575 feet ↘

SM spgs

Comal spgs

Elevation near 1400 feet ↘

SA spgs




Leona spgs

unique how
Unique? How?
  • 40+ species of Invertebrates
  • 4+ species of Vertebrates
discoveries made in the last 20 years
Discoveries made in the last 20 years
  • Diversity of Amphipods, snails & overall
  • Presence of marine relicts
    • Monodella
    • Some amphipod families
    • Foraminiferans
  • New species, deep aquifer system
  • More detailed information about vertebrates
community diversity
Community diversity
  • Greatest in Amphipods (12 species-5 families)
  • Other Arthropods (13 species representing 8 families)
  • Next is Mollusca (10 species of Hydrobiid snail family)
more about diversity
More about diversity
  • Biological diversity is important - Ecological stability
  • The species in this system may hold important genetic information
marine relicts
Marine relicts
  • Amphipods in the families: Hadziidae, Bogidiellidae, & Sebidae
  • These families are primarily marine with few examples of freshwater sp.
  • Hadziids are distributed today around the Caribbean and Mediterranean
  • These areas are important as remnants of the Tethys Sea
marine relicts17
Marine relicts
  • May assist in better understanding of how the aquifer formed and its relationship with paleomarine areas
  • Additional studies of these species will shed light on paleogeography
other marine relicts in the aquifer
Other marine relicts in the Aquifer
  • Monodella texana (Only N.A. Thermosbaenacean)
  • M. texana’s marine ancestors are represented by groups in the W. Indies
  • A Foraminiferan from the Lagenidae (Probably Robulus sp) was found
other marine relicts continued
Other marine relicts continued
  • Foraminiferans have only been found in fresh water from wells (Trans Caspian Province)
  • Cirolanid isopods (predominantly marine) are also found
new species
New species
  • 8 new snails, 2 others renamed
  • 10 new amphipods, 1 new family (Artesiidae)
  • 1 new aquatic beetle - Hadeoporus texanus (larvae & adult described)
  • 1 new vertebrate described - Typhlomolge robusta
texas state university artesian well
Texas State University Artesian Well
  • Drilled in 1895 to furnish water for Federal Fish Hatchery
  • Five foot cavern at 195 feet
  • Source of water is Edwards Aquifer
  • Sampled continuously since early 70’s
invertebrate fauna
Invertebrate Fauna
  • TURBELLARIA: (Flatworms)
  • Kenkiidae
  • Sphalloplana mohri Hyman
  • NEMATODA: (Roundworms)
  • Rhabdochonidae
  • Rhabdochona longleyi Moravec & Huffman
gastropods snails

Phreatodrobia conica Hershler & Longley Hueco cavesnail

P. coronae Hershler & Longley

P. imitata Hershler & Longley mimic cavesnail

P. micra (Pilsbry & Ferris) flattened cavesnail

P. nugax inclinata Hershler & Longley

P. nugax nugax (Pilsbry & Ferris) domed cavesnail

P. plana Hershler & Longley disc cavesnail

P. punctata Hershler & Longley high-hat cavesnail

P. rotunda Hershler & Longley beaked cavesnail

Phreatoceras taylori Hershler & Longley nymph trumpet

Balconorbis uvaldensis Hershler & Longley Balcones ghostsnail

Stygopyrgus bartonensis Hershler & Longley Barton cavesnail

Texapyrgus longleyi Thompson & Hershler striated hydrobe

Gastropods (Snails)
hirudinea leeches


  • Mooreobdella microstoma Pawlowski

Sphaeromicola (Hobbsiella) moria




Caecidotea reddelli (Steeves)

Cirolanides texensis Benedict


Lirceolus pilus (Steeves)

L. smithi (Ulrich) Texas troglobitic Water Slater

Mexistenasellus sp.

  • Hadziidae
  • Allotexiweckelia hirsuta Holsinger
  • Holsingerius samacos (Holsinger)
  • Texiweckelia texensis (Holsinger)
  • Texiweckeliopsis insolita (Holsinger)
amphipods continued
Stygobromus balconis (Hubricht)


S. bifurcatus (Holsinger)

S. flagellatus (Benedict)

S. pecki (Holsinger)

S. russelli (Holsinger)


Seborgia relicta Holsinger


Artesia subterranea Holsinger

Parabogidiella americana Holsinger

Amphipods continued
crustaceans continued


Monodella texana Maguire



Palaemonetes antrorum Benedict

P. holthuisi Strength

coleoptera insect beetles
COLEOPTERA:(Insect – beetles)
  • Dryopidae
  • Stygoparnus comalensis Barr & Spangler
  • Dytiscidae
  • Comaldessus stygius Spangler & Barr
  • Haideoporus texanus Young & Longley Edwards Aquifer water beetle
vertebrates pisces fish
  • Ictaluridae
  • Satan eurystomus Hubbs & Bailey Widemouth blindcat
  • Trogloglanis pattersoni Eigenmann Toothless blindcat
trogloglanis pattersoni
Trogloglanis pattersoni
  • Toothless blindcat
  • Found in same area of Widemouth Blindcat
  • Shallowest collection 1350’ below surface
  • Deepest 2000’
  • Only below San Antonio TX area
caudata tailed amphibians

Eurycea chisholmensis Chippindale, Price & Hillis Salado salamander

E. latitans Smith & Potter

Cascade Caverns salamander

E. naufragia Chippindale, Price & Hillis

E. sp.nov. Comal

E. nana Bishop

San Marcos salamander

E. neotenes Bishop & Wright

Texas salamander

E. pterophila Burger, Smith & Potter

Fernbank salamander

E. rathbuni (Stejneger)

Texas Blind salamander

E. robusta (Longley)

Blanco Blind salamander

E. sosorum Chippindale,Price & Hillis

Barton Springs salamander

E. tonkawae Chippindale, Price & HillisJollyville salamander

E. tridentifera Mitchell & Reddell

Comal blind salamander

E. troglodytes Baker

Valdina Farms salamander

E. sp.

Comal Springs salamander

CAUDATA:Tailed amphibians
history of management
History of Management
  • 1983 - EUWD given authority to regulate transport of water out of district (5 counties)
  • 1987 – EUWD gains legislative approval for a drought management plan (DMP)
  • 1988-90 – DMP requirements set
  • 1989 – Two western Counties withdraw from District
  • May 1991 – SA defeats construction of Applewhite Reservoir (Alternate source)
  • May 1991 – Sierra Club files suit against USFWS
history continued
History Continued
  • Sierra Club suit asks that USFWS be required to insure min. springflow to protect endangered species.
  • EUWD and SARA file suit against Living Waters (Catfish Well owners) for waste and water quality issues.
  • 1992 – TWC declares Edwards Aquifer to be an underground river, therefore regulated by the state
  • Later that year State Court invalidates TWCs determination
history continued53
History continued
  • Nov 16, 1992 Trial begins in U.S. District Court for Sierra Club lawsuit.
  • Jan 30, 1993 – U.S. Dist. Judge Bunton rule for the Sierra Club and orders:
    • Springflow must be maintained
    • TWC must submit plan to court by March 1993 to assure Comal & San Marcos Springs do not drop below Jeopardy levels
    • USFWS must develop springflow thresholds for take & jeopardy
    • Tx Legislature must develop regulations to limit withdrawals by May 31, 1993.
history continued54
History continued
  • May 30, 1993 – Texas Legislature adopts SB 1477 that creates the Edwards Aquifer Authority (EAA) with a 9 member appointed board
  • Aug. 30, 1993 – U. S. Justice Dept. ruled legislation may have violated the Voting Rights Act, in November they determined it did
  • Feb. 1994 – Fed. Court Appointed monitor to gather information for the court.
  • Less storage in aquifer (1ft of head = approx. 35,000 acre feet).
  • Low flows of San Marcos Springs occur sooner during critical dry periods.
  • Greater potential for saline water intrusion during critical periods.
  • Lower flows would possibly jeopardize listed species sooner.
threats to the system
Threats to the system
  • Historic lows vs. recent time (recharge & discharge)
  • Increasing water use
  • Aquifer Storage & recovery
  • Proposed policy to raise pumping caps
  • Proposed policy to limit minimal pumping required during drought
detailed studies past continuing
Detailed studies (Past & Continuing)
  • Texas Blind Salamander - Typhlomolge rathbuni
  • Two blindcatfish from San Antonio area: Satan eurystomus & Trogloglanis pattersoni (Ictaluridae)
  • Distribution of species throughout the aquifer, important in showing hydrologic relationships
studies currently underway
Studies currently underway
  • Water Quality - investigating freshwater/saline water interface
  • Modeling of groundwater hydrology and the effect of pumping
this system is a microcosm of problems in our world
This system is a microcosm of problems in our world
  • Population growth and human demands threaten the system and the surface ecosystems (springs) it supports
  • We should educate the users of water from the aquifer about its dynamics
  • Its importance as the habitat for a community of organisms
additional studies needed
Additional studies needed
  • Biomagnification of contaminants up the aquifer food chain
  • Toxicity studies of specific members of the aquifer community
  • Additional studies of rarer species
  • Energy flow and sources in the deep confined aquifer
  • The work on the aquifer through the years has been supported by USFWS, TPWD, USDA, USEPA and numerous other sources too numerous to mention.
  • Staff of the Research Center, Graduate Students, Collaborators and numerous others have assisted in developing the information about the Aquifer community.
  • Texas State University has been very supportive of this work.
thank you
Thank you!
  • I can be reached at the following:
  • email:
  • EARDC homepage:
  • Phone: 512-245-3581
  • Fax: 512-245-2669
  • Feel free to contact me with questions.