Review of the Edwards Aquifer Habitat Conservation Plan Report 3 (2018) / Chapter Skim
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4 Will the Minimization and Mitigation Measures Meet the Biological Objectives?
4 Will the Minimization and Mitigation Measures Meet the Biological Objectives?
Pages 97-156
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From page 97... ...
planting of submerged aquatic vegetation (SAV) including Texas wild rice and removal of nonnative vegetation, (4)
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From page 98... ...
Critical Period Management Comal and San Marcos 44% water withdrawal Stage V (5.1.4) reduction for municipal, industrial, and irrigation use based on spring flow and index well water levels FLOW PROTECTION MEASURES The four flow protection measures of the Habitat Conservation Plan (HCP)
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From page 99... ...
In the absence of observations during times of extreme drought, the basis for demonstrating the impacts of the flow protection measures on the flow in both systems is the MODFLOW model of the Edwards Aquifer. Since the original 2004 MODFLOW model was created to serve as the basis for the Bottom-Up program that frames the spring flow protection measures (HDR, Inc., 2011)
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From page 100... ...
. The section ends with a determination of whether the flow protection measures can achieve the flow component of the biological objectives in the HCP (see Chapter 3 for details on the flow objectives for the Comal and San Marcos systems)
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From page 101... ...
facility is the most expensive of the four flow protection measures. Withdrawn groundwater from the Edwards Aquifer is pumped via pipeline and stored underground in the Carrizo Aquifer at the SAWS ASR facility in south Bexar County.
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From page 102... ...
In NASEM (2017) , potential water quality concerns were raised regarding the SAWS ASR.
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From page 103... ...
These conditions are specific to the two main pools in the aquifer, the San Antonio and Uvalde pools. In the San Antonio pool, critical parameters are water levels in index well J-17 and flow rates at San Marcos Springs and Comal Springs (Figure 4-2)
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From page 104... ...
104 REVIEW OF THE EDWARDS AQUIFER HABITAT CONSERVATION PLAN FIGURE 4-2 Critical Management Program triggers for the San Antonio and Uvalde pools. SOURCE: Blanton and Associates (2018)
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From page 105... ...
runs of numerous models reflecting different recharge scenarios are complete, and the Bottom-Up package has been optimized using the updated and recalibrated MODFLOW model. The results of updated Bottom-Up analysis were presented by Jim Winterle in January 2018 and indicate that the minimum flow at Comal Springs for the August 1956 Drought of Record is 10 percent greater than the original MODFLOW Bottom-Up results (using all four flow protection measures; Figure 4-3)
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From page 106... ...
. FIGURE 4-4 Validation of updated MODFLOW model for J-17 water levels.
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From page 107... ...
Uncertainty in model validation against observed water-level elevations and spring flows is expected given the scale, hydrologic dynamics, and hydrogeologic complexities within the model domain. In general, errors were greater at peak flows than low flows during the validation period, and the calibration period shows greater differences at peak flows, with generally better agreement at low flows.
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From page 108... ...
Given the need to estimate minimum flows, it may also be useful to focus on errors during periods of low flow, for example, the magnitude and direction of the RMS and maximum deviations at the minimum flow. TABLE 4-2 Spring Target Calibration Summary Proposed Original 2004 Updated Error Statistic Criterion, cfs Model, cfs Model, cfs Comal Springs RMS error ≤50 37.9 26.2 Comal Springs maximum absolute ≤150 139 79.7 error San Marcos Springs RMS error ≤35 62 28.0 San Marcos Springs maximum ≤150 134 114.3 absolute error SOURCE: Data from Winterle (2018)
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From page 109... ...
. Taking all of this information into account, the Committee concludes that the flow protection measures will be effective in meeting the flow component of the biological objectives for all listed species.
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From page 110... ...
However, for the Comal Springs riffle beetle, this objective ap TABLE 4-3 Water Quality Protection Measures in the Habitat Conservation Plan M&M Measure Target (HCP Section) Spring System Contaminants Purpose Low-impact San Marcos Sediment, flow Prevent contamination development/BMPs from entering rivers (5.7.3)
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From page 111... ...
The discussion below will instead focus on the effectiveness of measures to maintain or improve water quality and recognizes that appropriately measuring success is an important and ongoing challenge. Stormwater Control Measures The City of San Marcos lies in one of the most rapidly developing counties in the country, with a reported 61 percent population increase from 2000 to 2010 (John Gleason LLC, 2017)
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From page 112... ...
Another type of SCM is bank stabilization, which can be used to reduce erosion in areas of high flow by use of rock walls, and other structures along a bank; this bank erosion contributes to sediment loads and habitat loss in streams. Bank stabilization projects are categorized as recreational M&M measures in the HCP and discussed in a subsequent section of this chapter.
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From page 113... ...
The City of New Braunfels Water Quality Protection Plan (WQPP; Alan Plummer Associates, 2017) and the WQPP for San Marcos and Texas State University (John Gleason LLC, 2017)
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From page 114... ...
. San Marcos System TABLE 4-5 Costs of Proposed Stormwater Control Projects near Landa Lake and the Old Channel The SCM plans in the San Marcos system are focused on Sessom Creek.
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From page 115... ...
monitoring for Sessom Creek input to the main stem of the San Marcos River. SOURCE: Pence (2018)
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. Comal System In the Comal Springs system, both bank restoration and other proposed SCMs have been located near the Old Channel and Landa Lake (Alan Plummer Associates, 2017; Figure 4-8)
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From page 117... ...
A number of bank stabilization projects have been implemented on Landa Lake by the City of New Braunfels and the Edwards Aquifer Authority, which are discussed in more detail in the section on Riparian ResSOURCE: John Gleason LLC (2017)
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From page 118... ...
Floating mats shade SAV, impede flowering of Texas wild rice, and degrade fountain darter habitat. Focal areas for vegetation mat management include Comal Springs, Landa Lake, the Old and New Channels of the Comal River, and the stretch of the San Marcos River from Sewell Park to interstate highway I-35.
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From page 119... ...
. Will the Water Quality Protection Measures Meet the Water Quality Objective for Fountain Darters?
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The HCP lays out four M&M measures related to aquatic plants. The first is specific for Texas wild rice (Zizania texana)
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From page 121... ...
At TABLE 4-6 Submerged Aquatic Vegetation Restoration Measures in the Habitat Conservation Plan M&M Measure (HCP Section) Spring System Target Species Texas wild rice enhancement and restoration San Marcos TWR, FD (5.3.1, 5.4.1)
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From page 122... ...
This recovery trend is not only good news for Texas wild rice, but it also aids in reaching the fountain darter biological goals. Expansion of Texas wild rice in the City Park region of the San Marcos River is shown in Figure 4-9.
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From page 123... ...
It seems clear that nonnative plant removal is one important factor in the 2017 resurgence of Texas wild rice in the San Marcos system. The City of San Marcos's efforts to remove nonnative SAV, plant Texas wild rice, and maintain the newly planted species via gardening appears to be highly successful thus far.
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From page 124... ...
As discussed in NASEM (2017) , there can be conflict between the objectives of planting native SAV and removing nonnative SAV when reestablishment of natives does not immediately replace the fountain darter habitat value lost with removal of the nonnative species.
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From page 125... ...
Figure 4-10 demonstrates that from 2013 to 2017 there has been a substantial shift in the SAV species found in the Old Channel, an area that has undergone extensive removal of nonnative SAV and replanting of native SAV. Table 4-8 shows the 2017 seasonal coverage of various native and nonnative SAV types in both the Old Channel LTBG reach and the Upper Spring Run LTBG reach.
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From page 126... ...
As discussed above, the City of San Marcos spends considerable time and resources on the planting of Texas wild rice, which occurs alongside efforts to restore other native SAV that provides superior habitat for the fountain darter in the San Marcos River. In 2017, these measures were focused on certain portions of the river, such as Spring Lake, the Spring Lake Dam LTBG reach, the City Park LTBG reach, the Cypress Island restoration reach, the I-35 LTBG reach, and the expanded I-35 restoration reach.
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From page 127... ...
In total, approximately 3,595 m2 of nonnative SAV were removed from the San Marcos system, and almost 46,000 individuals were planted in 2017 (including Texas wild rice)
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From page 128... ...
Work sites in 2016 had aquatic vegetation efforts (i.e., removal and planting) and included Spring Lake, Sewell Park, City Park, Hopkins Street–Bicentennial Park, Cypress Island, Rio-Vista Dam, and I-35.
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From page 129... ...
. The Texas wild rice ratio was eight plants for every resulting square meter of coverage.
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Will the SAV Restoration Measures Meet the Habitat Objectives for Texas Wild Rice and the Fountain Darter? With their documented success in planting and propagation to date, removal of nonnative SAV, and readjustment of SAV species included as fountain darter habitat, the Committee determines that these combined measures will be effective in meeting the habitat component of the biological goals for Texas wild rice and the fountain darter.
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From page 131... ...
Separately, it seems likely that removal of nonnative SAV is key to further expansion of Texas wild rice. As discussed further in Chapter 5, it would be desirable to have the systems become more self-maintaining.
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From page 132... ...
their habitats State Scientific Areas San Marcos TWR Prevent physical (5.6.1) damage to species and their habitats NOTE: CSRB = Comal Springs riffle beetle, FD= fountain darter; SMS = San Marcos salamander; TWR = Texas wild rice.
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From page 133... ...
Additional key recreation areas targeted in the HCP include Spring Lake and access points along the river on the Texas State University campus. "Recreation control is not meant to curtail recreation for large stretches of the river, but simply within key high quality habitat areas for Texas wild rice to limit unnecessary impacts during low-flow conditions." (EARIP, 2012)
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From page 134... ...
. A specific recreational M&M measure was for the City of San Marcos to establish permanent river-access points at several locations along the San Marcos River: City Park (see the black areas in Figure 4-12)
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. FIGURE 4-14 Lower Ramon Lucio Park access point.
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In collaboration with Texas State University, a Conservation Crew consisting of a team of university students was developed to educate the public about the HCP, with an emphasis on protected species, especially Texas wild rice. The Conservation Crew is active on the river annually from around Memorial Day to Labor Day.
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From page 137... ...
Boating in Spring Lake and Sewell Park Boating activities in Spring Lake and Sewell Park are regulated to minimize impacts to covered species and their habitats in the lake and in the San Marcos River. Boating M&M measures include limiting the number of boats on the water as well as designating access points and the areas where boats are allowed to operate (covered vessels include canoes, kayaks, and glass-bottom boats)
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From page 138... ...
for the purposes of education, scientific research, and preservation of flora and fauna of scientific or educational value. On March 29, 2012, the TPWD created an SSA designed to protect prime Texas wild rice habitat by restricting recreational activities during flows below 120 cfs in a two-mile reach of the San Marcos River from the Spring Lake Dam to the San Marcos wastewater treatment plant.
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From page 139... ...
. FIGURE 4-16 The four State Scientific Area exclusion areas, their size, and the extent of Texas wild rice included.
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From page 140... ...
Will Recreation Management Lead to Achievement of Texas Wild Rice and San Marcos Salamander Biological Objectives? The M&M measures associated with recreation management play an important role in meeting several key biological objectives in the HCP, particularly those pertaining to Texas wild rice and the San Marcos salamander.
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From page 141... ...
, have much less potential to impact this listed species as compared to Texas wild rice. Rather, the recreation-associated M&M measures in the HCP that regulate recreation in Spring Lake are intended to prevent physical disturbance of San Marcos salamanders and their benthic habitats.
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From page 142... ...
. Well-executed and monitored riparian management activities may also have positive effects on other listed species, for example, by mediating sediment loading and transport in the San Marcos system and thereby affecting the survival of Texas wild rice or by controlling the amount of shading or sedimentation, which can affect the growth of native SAV in both systems.
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From page 143... ...
NOTE: CSRB = Comal Springs riffle beetle; FD = fountain darter; SMS = San Marcos salamander; TWR = Texas wild rice. These riparian areas are dominated by rocky soils with limited water capacity, shallow bedrock, and limestone outcrops on 20- to 40-percent grades.
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From page 144... ...
In 2017, all of these riparian restoration activities continued along Spring Run 3 and the western shoreline (Figure 4-17)
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From page 145... ...
and the western shoreline of Landa Lake (bottom)
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From page 146... ...
has no discussion of the monitoring results. Riparian Restoration along the Old Channel Riparian restoration along sections of the Comal River that are not habitat for the CSRB is done primarily for the purposes of improving fountain darter habitat via reduction of erosion and sedimentation that might inhibit the growth of SAV.
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From page 147... ...
. Note that riparian restoration occurring in the vicinity of the San Marcos salamander (Spring Lake and the Spring Lake Dam region)
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From page 148... ...
Similarly, there is no measurement of how much sediment is being lost by these structures and entering the aquatic habitats, and there is no monitoring or measuring of aquatic sedimentation. Monitoring or measuring sedimentation and substrate impaction is necessary to evaluate the success of the riparian restoration activities relevant to the CSRB.
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From page 149... ...
There is no quantitative monitoring of aquatic sedimentation in the areas adjacent to riparian restoration. For these reasons, the Committee is unable to determine whether riparian management measures will achieve the biological objectives of the CSRB.
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From page 150... ...
The limited geographic distribution of these species leaves the populations vulnerable to extirpation throughout all or a significant part of their range. The purpose of the salvage refugia program is to collect and maintain captive stocks of listed Edwards Aquifer species (and genes)
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From page 151... ...
Primary long-term refugia populations are fully established for Texas wild rice, San Marcos salamanders, and fountain darters from the San Marcos River, and target numbers of fountain darters from the Comal River will likely be reached in 2018. Achieving target numbers for the other species will take at least several more years.
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From page 152... ...
The ratings could move to highly effective if there were less reliance on intensive planting efforts and less dependence on bryophytes as fountain darter habitat in the Comal system. The recreational management measures will be effective in meeting the habitat component of the biological objectives for the San Marcos salamander and Texas wild rice.
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From page 153... ...
Actions to support continued success include sustained maintenance of populations in more than one location, exploration of methods for long-term preservation of Texas wild rice propagules, and continued development of a vigorous applied research program. REFERENCES Alan Plummer Associates, Inc.
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From page 154... ...
2015. Edwards Aquifer Habitat Conservation Plan.
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From page 155... ...
2017. Review of the Edwards Aquifer Habitat Conservation Plan: Report 2.
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From page 156... ...
2014. Edwards Aquifer Habitat Conservation Plan, 2013 Annual Report.
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