USGS - science for a changing world

Pacific Coastal & Marine Science Center

Coastal Aquifer Project

Cartoon depicting an idealized SGD-influenced hydrogeologic cross-section. See also:


Increasing population density and changing agricultural practices in coastal areas have led to releases of nutrients (and other contaminants) into the coastal environment from fertilizer use, industrial practices, and wastewater discharge. These increased nutrient releases have led to eutrophication in many coastal waters, which is a widespread concern. Yet, the role that groundwater-derived nutrients has played in coastal eutrophication is not well understood in many areas. The ecological and economic impacts of eutrophication have been substantial in many coastal regions, which demands a better understanding of the contribution of groundwater-derived nutrient fluxes. Management of wastewater treatment practices in coastal regions critically depends on accurate estimates of the flux and quality of ground water in the coastal zone. In addition, informed resource management requires an improved understanding of the geological framework of coastal aquifers, the pathways by which ground water travels to the coastal zone, the specific locations and dimensions of submarine discharge zones, and the geochemical transformations that take place prior to discharge.

Basic science questions related to how fluid flux across ocean margins and fluid recirculation through ocean margin sediments affects elemental cycling at all scales are also scientific priorities of this research effort. Experiments that address more applied aspects of nutrient delivery can also yield information that is valuable for developing a more general understanding of land-ocean aquifer interactions.

While previously, the focus of the Coastal Aquifer Project was to examine geologic control on coastal aquifers and groundwater discharge, today it is apparent that knowledge of land–sea exchange must also encompass interplay among ecosystems science including ecosystems health and climate change-related processes, as well as natural geohazards.

Start/End Dates

10/1/2004 - 9/30/2018




The ultimate objective for this project is to be able to make accurate generalizations and predictions regarding rates and ecological consequences of SGD under differing hydrogeologic, geographical and climatological regimes. This collective work will thus permit a first-order national assessment of coastal submarine groundwater discharge impact. Current research goals include:

Seepage meter and subsurface temperature data collection.Approach

Our research depends critically upon techniques that have been refined over the years of the Coastal Aquifer Project. These techniques include qualitative mapping tools (e.g., radon-mapping, continuous resistivity profiling, shallow seismic, salinity mapping, etc) as well as quantitative passive and active techniques (e.g., radon times series, radium-quartet isotope models, seepage meters, well transects, and modeling).

The general long-term approach—developing a regional perspective of submarine ground-water discharge—is carried out with local studies at sites that are typologically representative of more general geological conditions and processes. In addition, consideration is given to mission and regional priorities of USGS (including WRD and BRD) and DOI, including management priorities of sister DOI bureaus and other federal agencies. To date, research has benefitted resource managers at Assateague Island, Cape Cod, and Fire Island National Seashores, as well as NSF-funded research partners.

Tasks and SubTasks

Products, Results, and Publications

Please visit the Submarine Groundwater Discharge web site for more information on this research.

Barnard, P.L., Foxgrover, A.C., Elias, E.P.L., Erikson, L.H., Hein, J.R., McGann, M., Mizell, K., Rosenbauer, R.J., Swarzenski, P.W., Takesue, R.K., Wong, F.L., and Woodrow, D.L., 2013, Integration of bed characteristics, geochemical tracers, current measurements, and numerical modeling for assessing the provenance of beach sand in the San Francisco Bay coastal system, in Barnard, P.L., Jaffe, B.E., and Schoellhamer, D.H., eds., A multi-discipline approach for understanding sediment transport and geomorphic evolution in an estuarine-coastal system—San Francisco Bay: Marine Geology, v. 345, p. 181–206, doi: 10.1016/j.margeo.2013.08.007

Baskaran, M. and Swarzenski, P.W., 2007, Short-lived radionuclides as tracers of anthropogenic activity in Tampa Bay, FL Marine Chemistry, 104, 27-42

Baskaran, M., Swarzenski, PW and Biddanda, BS 2008. Constraints on the utility of MnO2 cartridge method for the extraction of radionuclides: A case study using 234Th. Geochem. Geophys. Geosyst., 10, Q04011, doi: 10.1029/2008GC002340

Bowen, J. L., K. D. Kroeger, G. Tomasky, W. J. Pabich, M. L. Cole, R. H. Carmichael, and I. Valiela, 2007, A review of land-sea coupling by groundwater discharge of nitrogen to New England estuaries: Mechanisms and effects, Applied Geochemistry, 22:175-191

Bratton, John F., 2007, The importance of shallow confining units to submarine groundwater flow, in A New Focus on Groundwater-Seawater Interactions: in, Sanford, W., Langevin, C., Polemio, M, and Povinec, P., eds., IAHS Publication 312, p. 28-36

Bratton, John F., 2010, The three scales of submarine groundwater flow and discharge across passive continental margins, Journal of Geology, vol. 118, no. 5

John F. Bratton, John Karl Böhlke, David E. Krantc, Craig R. Tobias, 2009, Flow and geochemistry of groundwater beneath a back-barrier lagoon: The subterranean estuary at Chincoteague Bay, Maryland, USA: Marine Chemistry Volume 113, Issues 1-2, 30 January 2009, Pages 78-92, doi:10.1016/j.marchem.2009.01.004

Bratton, John F., Böhlke, J.K., Manheim, Frank T., Krantz, David E., 2004, Ground water beneath coastal bays of the Delmarva Peninsula: Ages and nutrients: Ground Water, vol. 42, no. 7, p. 1021-1034

Bratton, John; Guntenspergen, Glenn; Taggart, B. E.; Wheeler, Douglas; Bjorklund, Lynn; Bothner, Michael; Kotra, Rama; Lent, Robert; Mecray, E. L.; Neckles, Hilary; Poore, Barbara; Rideout, Stephen; Russell-Robinson, Susan; Weiskel, P. K., 2003, Coastal ecosystems and resources framework for science: USGS Open-File Report 03-405

Cable, J. E., Martin, J. B., Swarzenski, P. W., Lindenberg, M. K. and Steward, J. (2004), Advection Within Shallow Pore Waters of a Coastal Lagoon, Florida. Ground Water, 42: 1011–1020. doi: 10.1111/j.1745-6584.2004.tb02640.x

Chen, Z., Hu, C, Comny, R.N., Muller-Karger, F. and Swarzenski, P.W. (2007) Colored dissolved organic matter in Tampa Bay. Marine Chemistry, v. 104, 98-109

Cole, M. L., K. D. Kroeger, J. W. McClelland, and I. Valiela. 2005. Macrophytes as indicators of land-derived wastewater: Application of a N stable isotopic method in aquatic systems. Water Resources Research. 41, W01014, doi:10.1029/2004WRR003269

Cole, Marci L., Kevin D. Kroeger, J. W. McClelland, and I. Valiela, 2006, Effects of watershed land use on nitrogen concentrations and delta-15 nitrogen in groundwater, Biogeochemistry, 77:199-215.

Conaway, Christopher H., Storlazzi, Curt D., Draut, Amy E., and Swarzenski, Peter W., Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA: Journal of Environmental Radioactivity, Volume 120, June 2013, Pages 94-103, doi: 10.1016/j.jenvrad.2013.02.004

Conaway, Christopher H., Swarzenski, Peter W., and Cohen Andrew S, 2012, Recent paleorecords document rising mercury contamination in Lake Tanganyika: Applied Geochemistry, vol. 27 i. 1 pp. 352-359, doi: 10.1016/j.apgeochem.2011.11.005

Cross, VeeAnn A., John F. Bratton, Emile Bergeron, Jeff K. Meunier, John Crusius, Dirk Koopmans, 2006, Continuous Resistivity Profiling Data from the Upper Neuse River Estuary, North Carolina, 2004-2005: USGS Open-File Report 2005-1306

Crusius J., Berg P., Koopmans D. J., and Erban L. (2008) Eddy correlation measurements of submarine groundwater discharge. Mar. Chem. 109(77-85).

Crusius, J., Bratton, J., and Charette, M., 2004, Putting radon to work; identifying coastal groundwater discharge sites: USGS Open-File Report 2004-1381

Crusius J. and Kenna T. C. (2007) Ensuring confidence in radionuclide-based sediment chronologies and bioturbation rates. Estuarine Coastal And Shelf Science 71(3-4), 537-544.

Crusius J., Koopmans D., Bratton J. F., Charette M. A., Kroeger K. D., Henderson P., Ryckman L., Halloran K., and Colman J. A., 2005, Submarine groundwater discharge to a small estuary estimated from radon and salinity measurements and a box model. Biogeosciences 2, 141-157.

Dimova, NT, Swarzenski, PW, Dulaiova, H, and Glenn, C, 2012, Utilizing multichannel electrical resistivity methods to examine the dynamics of the fresh water–seawater interface in two Hawaiian groundwater systems: Journal Geophysical Research, v. 117, C02012, 12 PP.: doi:10.1029/2011JC007509

Dinicola, Richard S., Peter W. Swarzenski, and Jennifer Dougherty, 2011, Select Inorganic and Organic Loadings to Nearshore Liberty Bay, Puget Sound, Washington; In, Takesue, RK, ed., Hydrography of and biogeochemical inputs to Liberty Bay, a small urban embayment in Puget Sound, Washington: U.S. Geological Survey Scientific Investigations Report 2011–5152, Ch. 3.

Dougherty, J.A., Swarzenski, P.W., Takesue, R.K., Dinicola, R.S., and Reinhard, M., 2010, Occurrence of pharmaceutical and personal care product residues in surface and groundwater impacted by septic systems: Journal of Environmental Quality, 39:1–8. doi: 10.2134/jeq2009.0189

Ganguli, PM, Conaway, CH, Swarzenski, PW, Izbicki, JA, and Flegal, AR, 2012, Mercury speciation and transport in a California coastal lagoon system: The role of submarine groundwater discharge and monomethyl mercury production: Environmental Science and Technology, v.46, i.3, pp.1480−1488, doi:10.1021/es202783u

Garrison, V., Kroeger, K.D., Fenner, D., and Craig, P. 2007. Identifying nutrient sources to three lagoons at Ofu and Olosega, American Samoa using δ15N of benthic macroalgae. Marine Pollution Bulletin 54:1813-1838.

Greenwood, WJ, Kruse, S and Swarzenski, PW (2006) Extending electromagnetic methods to map coastal pore-water salinities. Ground Water, 44, 292-299. doi: 10.1111/j.1745-6584.2005.00137.x

Hu, CM, Chen, ZQ, Clayton, TD, Swarzenski, PW, Brock, JC and Muller-Karger, FE (2004) Assessment of estuarine water quality indicators using MODIS medium-resolution bands: Initial results from Tampa Bay. Remote Sensing of Environment, 93, 423-441. doi: 10.1016/j.rse.2004.08.007

Hu, C, Muller-Karger, F and PW Swarzenski (2006) Hurricanes, submarine ground-water discharge and west Florida's red tides. Geophys. Res. Lett., 33, L11601, doi: 10.1029/2005GL025449

Izbicki, John A.; Swarzenski, Peter W.; Burton, Carmen A.; Van De Werfhorst, Laurie; Holden, Patricia A.; and Dubinsky, Eric A., 2012, Sources of Fecal Indicator Bacteria to Groundwater, Malibu Lagoon and the Near-Shore Ocean, Malibu, California, USA: Annals of Environmental Science Vol. 6, Article 4,

Izbicki, JA, Swarzenski, PW, Reich, C, Rollins, C, and Holden, P. 2009. Sources of fecal indicator bacteria in urban streams and ocean beaches, Santa Barbara, CA. Annals of Environmental Scienc v., 3, 139-178.

Kim, G and Swarzenski, PW (2005) Submarine ground-water discharge (SGD) and associated nutrient fluxes to the coastal ocean. In, Carbon and Nutrient Fluxes in Continental Margins: A Global Synthesis. Eds., K.-K. Liu, L. Atkinson, R. Quinones, and L. Talaue-McManus, Springer-Verlag, New York.

Krantz, David E., Frank T. Manheim, John F. Bratton, Daniel J. Phelan, 2004, Hydrogeologic setting and ground-water flow beneath a section of Indian River Bay, Delaware: Ground Water, , vol. 42, no. 7, p. 1035-1051.

Kroeger, K.D. and Charette, M.A., 2007, Nitrogen biogeochemistry of submarine groundwater discharge. Limnology and Oceanography 53(3), 2008, 10251039

Kroeger, K.D., Cole, M.L., and Valiela, I. 2006. Groundwater-transported dissolved organic nitrogen exports from coastal watersheds. Limnology and Oceanography 51: 2248-2261

Kroeger, K D., Cole, ML, York, JK, and Valiela, I., 2006, Nitrogen loads to estuaries from waste water plumes: Modeling and isotopic approaches, Ground Water 44(2):188-200.

Kroeger, K.D., Swarzenski, P.W., Crusius, J., Bratton, J.F. and Charette, M.A. 2007. Submarine groundwater discharge: Nutrient loading and nitrogen transformations: USGS Fact Sheet 2006-3110

Kroeger, K.D., Swarzenski, P.W., Reich, C. and Greenwood, W.J. (2007) Submarine groundwater discharge to Tampa Bay: Nutrient fluxes and biogeochemistry of the coastal aquifer. Marine Chemistry, 104, 85-97

Manheim, Frank T., David E. Krantz, John F. Bratton, 2004, Studying ground water under Delmarva coastal bays using electrical resistivity: Ground Water, vol. 42, no. 7, p. 1052-1068

Martin, JM, Hartl, KM, Corbett, RD, Swarzenski, PW and Cable, JE (2003) A multi-level pore-water sampler for permeable sediments. J. Sedimentary Research, 73 (1): 128-132. doi: 10.1306/070802730128

Orem, William H.; Swarzenski, Peter W.; McPherson, Benjamin F.; Hedgepath, Marion; Lerch, Harry E.; Reich, Christopher; Torres, Arturo E.; Corum, Margo D.; Roberts, Richard E., 2007, Assessment of Groundwater Input and Water Quality Changes Impacting Natural Vegetation in the Loxahatchee River and Floodplain Ecosystem, Florida: USGS Open-File Report 2007-1304

Porcelli, D and Swarzenski, PW (2003) The behaviour of U- and Th series nuclides in groundwater and the tracing of groundwater. Reviews in Mineralogy and Geochemistry, 52: 317-361.

Roy, M., Martin, J. B., Cherrier, J., Cable, J. E., and Smith, C. G., 2010. Influence of sea level rise on iron diagenesis in an east Florida subterranean estuary. Geochimica et Cosmochimica Acta v. 74 i. 19, p. 5560-5573. doi: 10.1016/j.gca.2010.07.007

Roy, M., Martin, J. B., Smith, C. G., and Cable, J. E., 2011. Reactive-transport modeling of iron diagenesis and associated organic carbon remineralization in a Florida (USA) subterranean estuary. Earth and Planetary Science Letters v.304 i. 1-2 p. 191-201. doi: 10.1016/j.epsl.2011.02.002

Shedlock, R.J., and Bratton, J.F., 2009, Groundwater contributes nutrients to the Coastal Bays, in Shifting Sands: Environmental & Cultural Change in Maryland's Coastal Bays, Dennison, W.C., Thomas, J.E., Cain, C.J., Carruthers, T.J.B., Hall, M.R., Jesien, R.V., Wazniak, C.E., and Wilson, D.E., eds., University of Maryland Center for Environmental Science, Integration and Application Network.

Smith, C.G., Swarzenski, P.W., Dimova, N., Zhang, J. in press, 2012. Natural Radium and Radon Tracers to Quantify Water Exchange and Movement in Reservoirs. In Handbook of Environmental Isotope Geochemistry, Baskaran, M. (Ed.)Springer Berlin Heidelberg v. I Part II p 345-365. doi:10.1007/978-3-642-10637-8_18

Spruill, Timothy B., and John F. Bratton, 2008, Estimation of groundwater and nutrient fluxes to the Neuse River Estuary, North Carolina, Estuaries and Coasts, vol. 31, p. 501-520, doi: 10.1007/s12237-008-9040-0

Swarzenski, P.W. (2007) U/Th series radionuclides as tracers of coastal groundwater. Chemical Reviews, 107(2), 663-674, DOI: 10.1021/cr0503761

Swarzenski, P.W. and Baskaran, M. (2007) Uranium distributions in the coastal waters and pore waters of Tampa Bay, Florida. Marine Chemistry, Special Issue, Biogeochemical Cycles in Tampa Bay, Florida. Eds. P.W. Swarzenski and M Baskaran, 104, 43-57.

Swarzenski, P.W., Bratton, J.F., and Crusius, J., 2004, Submarine ground-water discharge and its role in coastal processes and ecosystems: USGS Open-File Report 2004-1226

Swarzenski, PW, Burnett, B, Reich, C, Dulaiova, H, Martin R and Meunier, J (2004) Novel geophysical and geochemical techniques to study submarine groundwater discharge in Biscayne Bay, Fl. USGS Fact Sheet 2004-3117.

Swarzenski, PW, Charette, M and Langevin, C (2004) An autonomous, electromagnetic seepage meter to study coastal groundwater/surface water exchange. USGS Open-File Report 2004-1369.

Swarzenski, PW and JL Kindinger. (2003) Leaky Coastal Margins: Examples of Enhanced Coastal Groundwater/Surface Water Exchange from Tampa Bay and Crescent Beach Submarine Spring, Florida, USA. In Coastal Aquifer Management, Monitoring and Modeling and Case Studies Eds A. Cheng and D. Ouazar. CRC/Lewis Press, pp 93-112

Swarzenski, P.W., Reich, C., Kroeger, K. and Baskaran, M. (2007) Ra and Rn isotopes as natural tracers of submarine groundwater discharge in Tampa Bay, FL. Marine Chemistry, 104, 69-84,

Swarzenski, PW, Orem, WG, McPherson, BF, Baskaran, M and Wan, Y. (2006) Biogeochemical transport in the Loxahatchee river estuary: The role of submarine groundwater discharge. Mar. Chem. 101, 248-265

Waldrop, WR, PW Swarzenski (2006) A new tool for quantifying flux rates between ground water and surface water. In, Coastal Hydrology and Processes. Eds VP Singh and YJ Xu. Water Resources Publications, pp 1-9



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