CWSS Projects
Current Projects
Learn more about current projects at the Center for Water Supply Studies.The Texas A&M University - Corpus Christi Center for Water Supply Studies, supported by the U.S. EPA’s Gulf Division, announces a unique opportunity to foster water quality in Nueces County Colonias and unincorporated communities. Through this initiative, community members are invited to apply for funding aimed at improving water quality in coastal colonias and unincorporated communities.
Through the prism of groundwater pollution: the interplay of extreme wet events, socio-economic well-being, and policy in unincorporated communities.
Texas A&M University–Corpus Christi | Coastal Management Program, Cycle 30
Texas A&M University - Corpus Christi will establish a new laboratory with advanced water quality testing equipment and trained personnel. Subrecipient will purchase equipment that can measure Enterococcus levels, E. coli levels, and complete E. coli source tracking.
Commencement of work on this project is contingent upon approval from the National Oceanic and Atmospheric Administration.
Past Projects
Learn more about past projects at the Center for Water Supply Studies.
All data for completed projects is archived on the Center's servers and is available by request to the CWSS Director.
Some data may be available through open access databases, such as GRIIDC. These databases are linked below.
Texas General Land Office Grants
Texas A&M University–Corpus Christi | Coastal Management Program, Cycle 27, 23-020-003-D597
Northern Padre Island’s dunes are the first—and often only—line of defense against hurricanes and sea-level rise. This two-year project mapped the island from the surface down to 30 m, revealing how hidden paleochannels, stratigraphic layers, clay layers, and a thinning freshwater lens interact and correlate with dunes and surface morphology. By fusing high-resolution LiDAR with >45 km of frequency domain electromagnetic surveys, 100 stations of time domain electromagnetic surveys, 12 well records, and 54 groundwater control points, the team produced the first island-wide breach-susceptibility layer. Findings pinpoint four “pinch-point” corridors where narrow, saline-prone dunes are most likely to fail during future storms. The study not only guides freshwater lens availability and vulnerability, dune-restoration priorities, and zoning decisions but also provides a transferable workflow for barrier islands statewide.
This research was funded in part by a Texas Coastal Management Program grant approved by the Texas Land Commissioner, providing financial assistance under the Coastal Zone Management Act of 1972, as amended, awarded by the National Oceanic and Atmospheric Administration (NOAA), Office for Coastal Management, pursuant to NOAA Award No. NA22NOS4190148. The views expressed herein are those of the author and do not necessarily reflect the views of NOAA, the U.S. Department of Commerce, or any of their subagencies.
Texas A&M University–Corpus Christi | GOMESA, Cycle 26, 21-155-009-C881 | PI: Dorina Murgulet | Co-PI: David Felix, Vikram Kapoor
This study highlights the importance of an interdisciplinary approach to understanding and managing hydrological and ecological challenges along the Texas Gulf Coast. By combining groundwater monitoring, sediment analysis, microbial source tracking, radium isotope tracing, and predictive modeling, we reveal critical links between regional hydrology and local coastal dynamics.
A key finding is that upstream streamflow significantly influences groundwater recharge, creating a direct connection between mainland watersheds and barrier island water tables. Seasonal peaks in streamflow during winter and spring raise water tables, increasing flood risks that threaten both human communities and ecosystems. These dynamics call for integrated management strategies that account for upstream water contributions and their coastal impacts.
Flooding is especially acute in permeable, sandy areas where shallow water tables heighten contamination risks. Failing septic systems and sewage backflow during high water events can introduce fecal indicator bacteria—traced to both human and canine sources—into nearshore waters, posing public health risks and compromising recreational water quality. Elevated bacteria levels may require beach closures or advisories, while nutrient inflows from these systems contribute to eutrophication and harmful algal blooms, further degrading coastal ecosystems. This underscores the need for responsive monitoring systems to track water table fluctuations and microbial threats.
The study also examines the role of nutrients like nitrogen and phosphorus, often linked to sewage overflows during flooding. These nutrients can destabilize coastal habitats, trigger algal blooms, reduce oxygen levels, and disrupt food webs. Shallow water tables can accelerate this process, serving as pathways for contaminant transport. Using radium isotopes, we identified submarine groundwater discharge (SGD) hotspots that align with periods of high water tables, signaling locations of nutrient-rich groundwater entering coastal waters.
Our predictive models provide tools to forecast water table dynamics and identify high-risk periods for flooding and contamination. These models can support early warning systems and timely public advisories. The findings also advocate for improving septic and sewage infrastructure in vulnerable areas and implementing land-use policies that reduce nutrient inputs.
By linking upstream water management with local coastal planning, this research promotes a holistic framework for mitigating health risks, protecting ecosystems, and ensuring sustainable resource management in the face of climate change and development pressures.
Texas A&M University–Corpus Christi | Coastal Management Program, 21-060-017-C677 | PI: Michael S. Wetz | Co-PI's: David Felix, Dorina Murgulet, Hussain Abdulla, Mohamed Ahmed
Baffin Bay is considered the “jewel” of the Texas coast, providing critical habitat for important fish species. However, it currently exhibits symptoms of water quality degradation that threaten the health of the bay and its valuable fishery. Earlier studies showed that the concentration of dissolved organic nitrogen (DON), linked to brown tide algal blooms, is 2-3-fold higher in Baffin Bay than other Texas estuaries, and that Baffin Bay has undergone a long-term increase (since 1970’s) in chlorophyll a (a proxy for algal biomass). These findings argue that nutrient pollution is a major factor in the declining water quality and ecosystem health of Baffin Bay.
In order to improve Baffin Bay ecosystem health, it is clear that large-scale watershed restoration aimed at reducing nutrient loads is needed. To do this, a reasonable accounting of nutrient sources must be in place. Here, a multidisciplinary team of researchers propose to quantify nutrient loadings to Baffin Bay from surficial, groundwater/benthic and atmospheric sources. The project goal is to identify the main source(s) of nutrients to help prioritize watershed restoration activities.
Results from high spatial resolution sampling in watershed creeks showed hot spots of nutrient enrichment, primarily at sites downstream of wastewater treatment plants, but also showed a general pattern of high nutrient levels (e.g., total nitrogen ≥ 100 µM) at nearly all locations sampled. Sampling conducted over wet-dry periods provided further evidence for the role of point sources (i.e., wastewater) in delivering nutrients to San Fernando Creek, while suggesting the possibility of both point- and nonpoint sources for Petronila Creek. In terms of dissolved inorganic nitrogen (DIN) sources, atmospheric deposition contributed roughly 3.7 kg N/(ha*yr) to the bay through rainfall. Stable isotope approaches determined that in the airshed, agriculture and vehicles were the primary NH3 emission sources; vehicle and intermittent sources (i.e., biomass burning and lightning) were the main NOx emission sources; vehicle, fertilizer, and marine sources were the dominant organic nitrogen emission sources. For the watershed creeks, wastewater was found to be a dominant source of DIN. However, DIN was only about 5% of total dissolved nitrogen (TDN) in Baffin Bay, which displayed high mean dissolved organic nitrogen (DON) concentrations year-round. The sum of allochthonous contributions (i.e., wastewater, manure, and wet deposition) to Baffin Bay represented over 60% of DON sources. Likewise, in tributaries, allochthonous sources contributed ~60-80% of DON and autochthonous source contributed ~2040%. Aside from atmospheric and surficial nutrient loadings, input of nutrients from sediment porewater and groundwater were found to be a significant, if not dominant source of nutrients to Baffin Bay. Both contained very high nutrient concentrations; groundwater NO3- averaged ~1064 µM and DON averaged ~64 µM concentrations while porewater NH4+ averaged ~325 µM. A dual isotope mixing model indicated that sewage and agriculture-derived NH4+ were the dominant sources to the NO3- in the groundwater.
Watershed nutrient reduction plans should be tailored according to the features of different regions in the watershed, as they may be subjected to varying nitrogen sources and processing. Based on the results of this study and available literature, nitrogen mitigation in both the watershed (incl. surficial creeks and groundwater) and airshed should focus particular attention on sources such as wastewater and septic sewage, followed by agricultural and animal sources as well as vehicles. A comprehensive list of nutrient reduction plans can be found in a soon-to-be released Watershed Protection Plan, which can be found here: https://baffin.twri.tamu.edu/
Texas A&M University–Corpus Christi | Coastal Management Program, Cycle 24, 20-036-000-B744 | PI: Dorina Murgulet | Co-PI: David Felix
Results of this study indicate that sewage or septic effluent is the dominant DON source to the nearshore Laguna Salada in Baffin Bay, regardless of the proximity to septic system/residential area (Riviera Fishing Peer -RP) or underdeveloped, more agricultural dominated area (Laguna Salada Research Site 55-S site). The high sewage/septic influence can be attributed to septic effluent release to groundwater and/or wastewater discharge to surface water, but high DON concentrations and enriched δ15N-DON in the groundwater strongly support the former. The sewage/septic contribution at RP (46.4 ± 4.7%) and LS 46.5 ± 7.2%) do not show significant differences. Overall, the highest sewage/septic contributions were observed in summer (June, July, and August) and fall (September, October, and November). The high pulse of submarine groundwater discharge (SGD)-related DON (and NH4+) in summer to early fall could be attributed to these observed inputs.
Both surface water locations at LS exhibit the least sewage/septic contribution (37.5 ± 0.1%) but highest fertilizer (18.2 ± 0%), livestock waste (21.7 ± 0.1%) and atmospheric deposition (22.7 ± 0.2%) contribution in spring (March, April, and May). This is potentially the result of higher precipitation (the highest amounts for the duration of the study occurred in May), which is followed by an increase in SGD rates, only slightly shy to the rates following Hurricane Hanna. The least sewage/septic contribution (42.5 ± 3.0%) but highest fertilizer (16.9 ± 0.6%), livestock waste (20.0 ± 1.1%) and atmospheric deposition (20.7 ± 1.5%) contribution at RP was estimated in winter (December, January, and February). This can be explained by SGD-derived inputs that seemed to be elevated by Hurricane Hanna at the end of July and the additional precipitation in September. In winter, when precipitation is much lower, and riverine/surface runoff input is also lower, DON SGD fluxes were among the lowest measured, also reflected by 7 the lower surface water concentrations. In this season, the relative contribution of fertilizer, livestock waste and atmospheric deposition to the surface water DON pool were the highest. A decreased flux of nearshore SGD leads lo lower inputs of septic and in turn decreases the SGDderived DON flux but increase the contribution of fertilizer, livestock waste and atmospheric deposition. This is expected to bring in more inputs of NOx and NH4+, as indicated by the SGDderived fluxes of these solutes, which as opposed to DON, are increasing in fall and winter.
Texas A&M University–Corpus Christi | Coastal Management Program, Cycle 21, 17-182-000-9819 | PI: Dorina Murgulet | Co-PI: Valeriu Murgulet
This study aimed to evaluate the seasonal role of groundwater inflows and nutrient transport to South Texas bay systems to inform environmental flow recommendations and nutrient criteria. Groundwater discharge data and nutrient flux estimates contribute to improving management tools used by agencies such as TCEQ, USEPA, and the Texas Water Development Board (TWDB).
Surface water data showed that dissolved organic nitrogen (DON) generally increases from Aransas Bay to Baffin Bay, while dissolved inorganic nitrogen (DIN) was highest in Oso Bay during winter 2017 and 2018. Ammonium concentrations peaked in Baffin Bay, followed by Oso Bay. Porewater nutrient concentrations followed similar spatial trends and were consistently higher than those in the overlying water column, especially for ammonium, which was 10 to 100 times more concentrated in porewater.
Submarine groundwater discharge (SGD) rates varied by location. The highest seasonal averages were in Nueces Bay and University Beach (109 and 107 cm/day), while Baffin Bay, Laguna Madre, and Aransas Bay had the lowest (15, 19, and 28 cm/day, respectively). Despite some local variability, overall SGD rates remained relatively consistent across seasons: 51 cm/day (winter 2017), 45 cm/day (spring 2017), and 69 cm/day (summer 2017 and winter 2018).
Spatial and temporal variation in nutrient concentrations had a greater influence on solute fluxes than seasonal changes in SGD rates. Nitrate fluxes were highest in Oso Bay and Baffin Bay (seasonal averages of 65.6×10³ and 5.3×10³ μmol/m²/day). Ammonium fluxes were especially elevated in Baffin Bay (227.8×10³ μmol/m²/day), followed by Aransas Bay (96.3×10³ μmol/m²/day), with other bays showing much lower values.
SGD-derived total organic carbon (TOC) fluxes increased from north to south, with Baffin Bay nearly doubling Aransas Bay values (529.1×10³ vs. 290.1×10³ μmol/m²/day). Silica and phosphate fluxes mirrored porewater and surface water concentration patterns. Phosphate fluxes were highest in Oso Bay (10.1×10³ μmol/m²/day) and lowest in Laguna Madre (1.3×10³ μmol/m²/day). Silica fluxes peaked in Baffin Bay (255.3×10³ μmol/m²/day) and were lowest at University Beach (90×10³ μmol/m²/day).
These findings emphasize the significance of SGD as a nutrient source, particularly in nutrient-limited systems like those in South Texas. The results also support the need to include groundwater-derived inputs in nutrient budgets and flow management strategies to better protect estuarine water quality.
Read this project's published work: https://doi.org/10.1016/j.scitotenv.2022.15381
Texas A&M University–Corpus Christi | Coastal Management Program, Cycle 21, 17-180-000-9817 | PI: Xinping Hu | Co-PI: Dorina Murgulet
Copano Bay, part of the Mission-Aransas Estuary, has shown long-term signs of acidification, including declining pH and total alkalinity. This trend has been linked to reduced freshwater inflows, which increase water residence time and allow acidification processes to intensify. Notably, there appears to be an additional alkalinity sink beyond reduced inflow, particularly during droughts. Understanding this sink is critical, as Copano Bay supports the southernmost commercial oyster fishery in Texas, and oysters are highly sensitive to shifts in carbonate chemistry.
This study investigated submarine groundwater discharge (SGD) as a potential driver of this acidification. In other semi-arid estuaries, SGD has been associated with acidity from the oxidation of reduced compounds in sediments. Over two years of monitoring, data showed that total alkalinity in Copano Bay closely tracked river discharge, with the influence of SGD most apparent during low-flow periods. Although hypersaline conditions were expected, they were not observed during the study. However, continuous radon monitoring revealed significant spatial and temporal variability in SGD.
Differences in porewater δ¹⁸O and δD between years suggest that SGD responds to interannual changes in freshwater inflow. In the water column, major ions like calcium, magnesium, potassium, and sulfate correlated well with chloride, reflecting conservative mixing. In contrast, porewater concentrations of these ions exceeded conservative mixing expectations, indicating production through SGD and subsurface geochemical reactions.
Excess sulfate in porewater may result from the oxidation of reduced sulfur species, transported to the bay via SGD or porewater recirculation. This process can contribute to acidification. Benthic flux calculations of alkalinity and dissolved inorganic carbon (DIC) based on SGD rates were an order of magnitude higher than those based on diffusion alone. While diffusion-derived DIC flux was ~28% greater than alkalinity flux, SGD-derived alkalinity flux slightly exceeded DIC flux, suggesting that oxidation of reduced species may offset or reverse alkalinity production, leading to net acidification.
Overall, the findings support the idea that SGD introduces acidity to Copano Bay, particularly under low-flow conditions. This process likely contributes to the estuary’s long-term alkalinity decline and poses a risk to carbonate-sensitive species like oysters. Recognizing and incorporating SGD-driven acidification into estuarine management is essential for sustaining ecosystem health and shellfish productivity in Copano Bay.
Impacts of Temporal and Spatial Variation of Submarine Groundwater Discharge on Nutrient Fluxes to Texas Coastal Embayments, Phase III (Baffin Bay)
Texas A&M University–Corpus Christi | Coastal Management Program, Cycle 20, 16-060-000-9104 | PI: Dorina Murgulet | Co-PI: Valeriu Murgulet
This study aimed to understand the role of submarine groundwater discharge (SGD) and nutrient transport to Baffin Bay to inform environmental flow recommendations and nutrient criteria for Texas estuaries. The analysis focused on mostly dry conditions in January, July, and November 2016.
Groundwater discharge rates varied by location and season, but average bay-wide SGD rates showed little seasonal change. Mobile surveys using radon-222 indicated rates of 35.8 cm·d⁻¹ in July and 22.7 cm·d⁻¹ in November. Estimates from radium-226 showed similarly modest seasonal variation. However, nutrient concentrations in porewater varied significantly, particularly for ammonium, which was much higher than in other South Texas estuaries—reaching 5,531 µmol·L⁻¹ in July and dropping to 38.6 µmol·L⁻¹ in January.
This indicates that SGD-derived nutrient fluxes are driven more by porewater nutrient levels than by seasonal changes in discharge rates. For example, dissolved inorganic nitrogen (DIN) contributions from SGD were estimated at 1,029.4×10¹¹ µmol·d⁻¹ in July—over four times higher than the November value of 235.1×10¹¹ µmol·d⁻¹. Orthophosphate and hydrogen silicate followed similar trends, with significantly higher fluxes in July than in November. Dissolved organic carbon (DOC) from SGD was also higher in July (598.7×10¹¹ µmol·d⁻¹) than November (480.1×10¹¹ µmol·d⁻¹).
In contrast, surface water inflows—assuming consistent solute concentrations—were much lower. DIN from surface sources was 39.4×10⁸ µmol·d⁻¹ in January, decreasing to 7.5×10⁸ in July and 4.7×10⁸ in November. Similar seasonal patterns were observed for orthophosphate, silicate, and DOC. For all nutrients except nitrate, SGD inputs greatly exceeded surface runoff, often by several orders of magnitude.
Overall, SGD delivers far more nitrogen (mostly as ammonium), phosphate, silicate, and DOC to Baffin Bay than surface runoff. Nitrate likely enters through surface flows, while SGD may provide more nitrite. The magnitude and nutrient content of SGD—whether fresh or saline—make it a critical input to this shallow estuarine system.
Persistent winds likely drive saline groundwater recirculation, while episodic rain events may enhance fresher groundwater inflows. Both processes contribute to porewater solute diffusion into the water column, emphasizing SGD’s importance in shaping nutrient dynamics in Baffin Bay.
Texas A&M University–Corpus Christi | Coastal Management Program, Cycle 19, 15-047-000-8392 | PI: Dorina Murgulet | Co-PI: Michael Wetz
This study aims to improve understanding of groundwater inflows and nutrient transport to South Texas bay systems by incorporating submarine groundwater discharge (SGD) into freshwater inflow needs and nutrient budgets. This is critical for refining environmental flow recommendations and nutrient criteria for Texas estuaries.
A key finding is the persistent nitrogen (N) limitation in the Mission-Aransas Estuary across all sampled seasons (winter, summer, fall), even during periods of high river discharge such as the late spring and summer of 2015. This supports earlier studies showing that nitrogen, not phosphorus, is typically the limiting nutrient in Texas estuaries, largely due to limited river inflow in South Texas.
Porewater samples revealed inorganic nutrient concentrations—especially ammonium and orthophosphate—ranging from 1 to over 100 times higher than those in the water column. This suggests porewater is a potentially significant, though intermittent, nutrient source. Organic nutrients, particularly dissolved organic nitrogen (DON), also varied widely, indicating a possible but spatially inconsistent contribution to estuarine nutrient dynamics.
SGD in the Mission-Aransas Estuary was measured during excessively wet (July 2015) and moderately wet (November 2015) conditions. Despite seasonal differences, average bay-wide SGD rates remained relatively constant: 40.4 cm/day in July and 39.1 cm/day in November. However, nutrient fluxes were more influenced by the spatial distribution of porewater nutrient concentrations than by seasonal hydrologic variation.
While SGD-derived total dissolved nitrogen (TDN) fluxes along the mainland shoreline of Copano and Aransas Bays were much lower than riverine inputs, their relative importance changes with hydrologic conditions. During a wet year, shoreline SGD-derived TDN fluxes were nearly four orders of magnitude lower than Mission River inputs. During a dry year, this gap narrowed to about two orders of magnitude, showing SGD's increasing relevance during drought conditions.
Although not directly compared, organic nutrient fluxes via SGD may exceed inorganic fluxes in magnitude and significance. However, due to heterogeneity in groundwater flow and porewater chemistry, SGD estimates cannot be extrapolated across the entire bay without further data. Additionally, sediment benthic fluxes—potentially driven by persistent wind mixing in these shallow bays—may also be a notable nutrient source.
Overall, this study highlights the need to consider groundwater and sediment-derived nutrient sources in setting regulatory nutrient criteria. These insights are especially important for agencies like the Texas Commission on Environmental Quality (TCEQ) and the U.S. Environmental Protection Agency (USEPA) working to protect estuarine health under variable hydrologic conditions.
Texas A&M University–Corpus Christi | Coastal Management Program, Cycle 18, 15-047-000-8392 | PI: Dorina Murgulet | Co-PI: Michael S. Wetz
Submarine groundwater discharge (SGD) is a key component of coastal hydrology and biogeochemistry, linking land-based water and nutrient sources to marine environments. This study focused on understanding nutrient and organic matter inputs from SGD into southeastern Corpus Christi Bay and the Upper Laguna Madre, particularly their roles in fueling phytoplankton growth and contributing to hypoxia.
Data were collected from January to December 2014 at 29 stations across the region. SGD rates were specifically monitored in summer and fall at three selected sites using time-lapse electrical resistivity (ER) and continuous radon-222 measurements. Estimated groundwater fluxes ranged from 1.1 to 5.7 m³/m/day in summer and from 1.5 to 9.7 m³/m/day in fall.
Porewater samples revealed high concentrations of nutrients, especially in fall. Average concentrations in summer included 1,549 µmol/L dissolved organic carbon (DOC), 325 µmol/L total dissolved nitrogen (TDN), 761 µmol/L ammonium, and 335 µmol/L silica. In fall, these values increased to 3,778 µmol/L DOC, 2,345 µmol/L TDN, 1,717 µmol/L ammonium, and 566 µmol/L silica. Levels of ammonium, DOC, and silica were consistently much higher at SGD sites than in surrounding seawater.
Using the measured SGD rates and nutrient concentrations, nutrient fluxes were estimated for the Corpus Christi Bay system. In summer, SGD delivered 1.3 mol/day of dissolved inorganic nitrogen (DIN), 5.5 mol/day of DOC, 1.3 mol/day of TDN, 1.4 mol/day of silicate, and 0.09 mol/day of orthophosphate per meter of shoreline. By fall, these values increased approximately tenfold: 16.2 mol/day of DIN, 32.5 mol/day of DOC, 22.0 mol/day of TDN, 5.0 mol/day of silicate, and 0.3 mol/day of orthophosphate per meter.
Potential SGD hotspots correspond closely with hypoxia-prone areas in Corpus Christi Bay, suggesting that SGD contributes significantly to nutrient enrichment and microbial respiration that drive oxygen depletion. Though spatially patchy, the influence of SGD on water column chemistry is likely substantial under the observed environmental conditions.
The study also revealed high spatial variability in hydrogeology and hydrology across the region, as shown by ER and isotope analyses. These findings underscore the need for further research to better characterize the system and accurately scale nutrient input estimates across the entire bay complex.
Importantly, results suggest that the Upper Laguna Madre is strongly influenced by groundwater inputs, which may play a role in triggering harmful algal blooms such as brown tides. Overall, this study emphasizes the critical role of SGD in coastal nutrient dynamics and the need to integrate groundwater into estuarine management strategies.
National Science Foundation (NSF)
Texas Sea Grant
Texas A&M University–Corpus Christi | Texas Sea Grant
More information coming soon.