Review of the Edwards Aquifer Habitat Conservation Plan Report 2 (2017) / Chapter Skim
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1 Introduction
1 Introduction
Pages 11-24
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From page 11... ...
The two largest springs emanating from the Edwards Aquifer -- Comal Springs in New Braunfels and San Marcos Springs in San Marcos -- are home to a number of endemic fish, amphibians, insects, and plants found nowhere else in the world. Because of the potential for reduced spring flow during drought, eight of these species are listed as threatened or endangered under the federal Endangered Species Act (ESA)
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From page 12... ...
. the San Marcos salamander, the Comal Springs dryopid beetle, the Comal Springs riffle beetle, the Peck's Cave amphipod, and Texas wild rice.
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From page 13... ...
At least six springs occur within the artesian zone, including the two largest in Texas, the San Marcos and Comal Springs. Comal and San Marcos Springs are located within the San Antonio segment of the Edwards Aquifer, which spans approximately 3,600 square miles and is the focus of the Habitat Conservation Plan and this report.
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From page 14... ...
All species in the system depend on adequate spring flow, such that reduced flow in Comal and San Marcos Springs has periodically resulted in the intermittent loss of habitat and decreased populations. This loss of habitat from reduced flow is the main reason that eight species have been listed for protection under the federal Endangered Species Act (ESA)
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From page 15... ...
* Listed as undefined status by the USFWS HABITAT CONSERVATION PLAN The ESA, which in this case is enforced by the U.S.
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From page 16... ...
. Beyond spring flow protection measures, there are a variety of minimization and mitigation measures designed to maintain and restore the habitat of ESA-listed species at both Comal and San Marcos Springs.
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From page 17... ...
It mentioned several techniques for doing this, including conducting more explicit sensitivity analysis; validating the groundwater model by testing its predictive abilities using data from a time period not included in the model calibration; using additional calibration and validation metrics; using PEST predictive uncertainty analysis; using the ensemble method; and having confidence intervals presented with all modeling results. Unlike the hydrologic modeling, the ecological model was new to the HCP; thus the Committee recommended creation of a conceptual model to help determine the most important processes for a model to encompass and to show the links between flow, species populations, and other important parameters.
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From page 18... ...
It noted that, because none of the sampling locations were selected using randomization procedures, results from the monitoring program are not representative of the entire spring and river systems and cannot provide system-wide estimates of population densities of target species. Enhanced sampling for nutrients and the development of new quantitative sampling methods for the Comal Springs riffle beetle were recommended.
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From page 19... ...
The primary focus in this report is to help develop questions that both the hydrologic and ecological models can be used to answer, and to evaluate implementation of the minimization and mitigation measures that are b eing used to protect and restore habitat and protect flow. The question of BOX 1-1 Review of the Edwards Aquifer Habitat Conservation Program -- Phase 2 Statement of Task A committee of the National Academies of Sciences, Engineering, and Medi cine will: 1.
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From page 20... ...
In particular, the model will be used to determine whether the four spring flow protection measures of the HCP can maintain flows at Comal and San Marcos Springs above levels critical to the listed species for sufficient durations. Ecological Model The ecological modeling described in the HCP has been under development since 2013 and is the subject of a short report from this Committee, released in June 2016 (NASEM, 2016; see Appendix A)
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From page 21... ...
The current program monitors the following components: • Aquatic vegetation mapping, including Texas wild rice • Fountain darter and fish community sampling • San Marcos salamander sampling • Comal Springs riffle beetle monitoring • Comal Springs invertebrate sampling • Comal Springs salamander sampling A final goal of the biomonitoring program is to provide information to effectively determine whether the conservation measures are achieving the biological goals and objectives set forth in the HCP. Water Quality Monitoring Water quality monitoring has been in place in the Comal and San Marcos Spring systems for more than 40 years.
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From page 22... ...
Spring Flow Protection Measures Task 4 in the Statement of Task brings a new topic under the Committee's purview, namely the ability of certain minimization and mitigation measures to provide benefits to the listed species. The four spring flow protection measures that are evaluated include the Voluntary Irrigation Suspension Program Option, the Regional Water Conservation Program, the Aquifer Storage and Recovery program of SAWS, and emergency withdrawal reductions during Stage V Critical Period Management.
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From page 23... ...
Chapter 3 describes the ecological modeling for Comal and San Marcos Springs, focusing on the initial modeling efforts for the fountain darter and SAV. It builds on a short interim report (NASEM, 2016)
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From page 24... ...
2016. Evaluation of the Predictive Ecological Model for the Edwards Aquifer Habitat Conservation Plan: An Interim Report as Part of Phase 2.
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