Thomas Harter, Ph.D.
Robert M. Hagan Endowed Chair, Water Management and Policy
Professor and Cooperative Extension Specialist for Groundwater Hydrology
Chair, Hydrologic Sciences Graduate Group
Department of Land, Air and Water Resources
University of California, Davis, CA 95616-8628
Telephone: (530) 752-2709 Fax: (530) 752-5262 E-mail: firstname.lastname@example.org Web: Cooperative Extension Program in Groundwater Hydrology
Relevant Scientific and Professional Experience:
Since 1995: Professor and Cooperative Extension Specialist, University of California, Davis
Development of groundwater and vadose zone research program with emphasis on numerical modeling, stochastic analysis, and field characterization of soil and groundwater flow and contaminant transport, application of research efforts to groundwater quality, non-point source pollution, and groundwater resources problems in the State of California, development and administration of a cooperative extension program (shortcourses, presentations, workgroups) focused on issues relating to soil water quality, groundwater quality, and groundwater resources.
1994-1995: Consultant with Errol L. Montgomery and Associates, Tucson, Arizona
Design and implementation of groundwater modeling projects, contaminant transport studies, hydrogeologic assessment and impact review of pit-mining operations.
1990-1994: Research Associate and Postdoctoral Fellow, University of Arizona
Planning and implementation of theoretical and numerical research in stochastic subsurface hydrology concerning flow, transport, and chemical processes in unsaturated porous media.
1987-1989: Research Assistant, Universität Stuttgart, Germany
Investigation of pesticide movement in laboratory soil columns for the validation of existing numerical pesticide transport models. Hydrogeologic field work to establish groundwater study site.
1986-1987: Hydrologist Intern, Pima Association of Governments, Tucson, Arizona
Study on potential pollution hazards in the Tucson metropolitan area.
- PhD, Hydrology, University of Arizona, 1994
- MS(Diplom), Physical Geography/Hydrology, Universität Freiburg & Universität Stuttgart, Germany, 1989
- BS (Vordiplom), Physical Geography/Hydrology, Universität Freiburg, 1985
Honors, Fellowships, Awards:
2007-current, Robert M. Hagan Endowed Chair, Water Management and Policy
2007, Kevin J. Neese Award, Groundwater Resources Association of California
1991/92,Harshbarger Fellow, University of Arizona
1985/86, Fulbright Scholar, University of Arizona
1983/89, Fellow of the Studienstiftung des Deutschen Volkes, Bonn, Germany
American Geophysical Union
European Geophysical Union
International Association of Hydrologic Science
National Ground Water Association
Groundwater Resources Association of California
Professional Committee Memberships (Current)
- Groundwater Resources Association of California, Board of Directors
- Water Education Foundation, Board of Directors
- American Geophysical Union, Hydrology Section, Technical Committee Member
- Scott Valley/Klamath Basin Groundwater Advisory Committee
- State Water Board/Central Valley Regional Water Board: Groundwater Monitoring Advisory Committee, Dairy Representative Monitoring Advisory Committee, CV SALTS Technical Advisory Committee
- California Dairy Quality Assurance Program
- Associate Editor, Journal of Environmental Quality
- Associate Editor, Vadose Zone Journal
- Water Resources Research
- Journal of Hydrology, Journal of Contaminant Hydrology
- Journal of Environmental Quality
- Journal of Environmental Science and Technology
- Transport in Porous Media
- Ground Water
- Vadose Zone Journal
- ASCE Journal of Irrigation and Drainage Engineering
- USDA (proposal reviews)
- NSF (proposal reviews)
Representative Project Experience
Deep Vadose Zone Characterization and Flow/Contaminant Transport Modeling; Principal investigator on several studies to investigate deep groundwater recharge and nitrate/pesticide transport in thick, heterogeneous, alluvial vadose zones; including field characterization, laboratory measurements, and advanced computer modeling.
Groundwater Modeling Research Projects; Principal investigator on projects involving the development of basin groundwater- and surface water models, e.g., for the development of a conjunctive use management strategy in a 1,500 sq. mile watershed, eastern Tulare Lake Basin, California, and for sustainable groundwater management that protects base-flow conditions in the Scott River, Klamath Basin, California; development of a regional stochastic groundwater model for the assessment of deep groundwater contamination from shallow saline water in a 550 square mile watershed in the Western San Joaquin Valley, California; development and application of groundwater transport modeling software with applications to California's Central Valley and Salinas Valley. Modeling projects involve model conceptualization, data compilation, data processing, integration of geostatistical, GIS, database, and groundwater modeling software (GSLIB, ArcGIS, MS Access, MODFLOW, MT3D, RWHET), programming (Fortran, Matlab, Comsol, R), model calibration, application, and research.
Contaminant Emission and SubsurfaceTransport in (Animal) Agriculture; Principal Investigator and Co-Investigator on a suite of research and extension projects dealing with groundwater contamination from dairies and other confined animal facilities, and from other agricultural landuses; long-term pollution; field reconnaissance, monitoring, groundwater modeling (flow, transport, quality); development of monitoring networks and best management practices; environmental fate and transport of salts, nitrate, pathogens (Cryptosporidium, E. Coli H7 O157, Salmonella, Campylobacter), antibiotics and other pharmaceuticals, steroid hormones, groundwater forensics related to animal farming; mathematical/computational methods for fate and transport modeling, upscaling across bench-, plot-, field-, farm-, to regional scale.
Pathogen Transport of C. parvum in Porous Media; Principal Investigator and Co-Investigator on two projects to develop a quantitative model, to estimate transport properties of Cryptosporidium parvum in porous media, and to evaluate the role of subsurface transport in buffer strips near surface waters.
UC Davis Hydrology 144 (undergraduate/graduate course): Groundwater Hydrology
UC Davis Hydrology 274 (graduate course): Practical Groundwater Modeling
University of Freiburg (graduate course): Global Groundwater-Agriculture Nexus
Shortcourse: Introduction to Groundwater and Watersheds
Shortcourse: Introduction to Groundwater Modeling
Shortcourse: Introduction to Vadose Zone Hydrology
Miller, C.M.F., H. Waterhouse, T. Harter, J.G. Fadel, D. Meyer, 2020. Quantifying the uncertainty in nitrogen application and groundwater nitrate leaching in manure based cropping systems. Agricultural Systems (in press).
Wickham, P., S. Sandoval-Solis, P.K.Pandey, 2020. UV light and temperature induced fluridone degradation in water and sediment and portential transport into aquifers, J. Envronm. Poll. (in press)
Escriva-Bou, A., R. Hui, S. Maples, J. Medellin-Azuara, T. Harter, J.R. Lund, 2020. Planning for groundwater sustainability accounting for uncertainty and costs: An application to California's Central Valley, J. Environ. Management, doi:10.1016/j.jenvman.2020.110426
Bastani, M., T.Harter, 2020. Effects of upscaling temporal resolution on groundwater nitrate transport model performance at the regional management scale. Hydrogeology J., doi:10.1007/s10040-020-02133-x (open access)
Henri, C., T. Harter, 2020. On the conceptual complexity of non-point source management: Impact of spatial variability. Hydrol. and Earth Systems Sci, doi:10.5194/hess-24-1189-2020 (open access)
Tolley, D., L. Foglia, T. Harter, 2019. Sensitivity analysis and calibration of an integrated hydrologic model in an irrigated agricultural basin with a groundwater-dependent ecosystem. Water Resour. Res., doi:10.1029/2018WR024209 (open access)
Kourakos, G., H.E. Dahlke, T. Harter, 2019. Increasing groundwater availability and seasonal baseflow through agricultural managed aquifer recharge in an irrigated basin. Water Resour. Res., doi:10.1029/2018WR024019 (open access)
Bastani, M. and T. Harter, 2019. Source area management practices as remediation tool to address groundwater nitrate pollution in drinking supply wells. J.Contam.Hydrol. 226 (103521), 17p., doi:10.1016/j.jconhyd.2019.103521 (open access)
Henri, C. and T. Harter, 2019. Stochastic assessment of nonpoint source contamination: Joint impact of aquifer heterogeneity and well characteristics on management metrics. Water Resour. Res., doi:10.1029/2018WR024230 (open access)
Owen, D., A. Cantor, N. Green Nylen, T. Harter, and M. Kiparsky, 2019. California groundwater management, science-policy interfaces, and the legacies of artificial legal distinctions. Env. Res. Lett. 14(4). doi:10.1088/1748-9326/ab0751
Ghasemizade, M., K.O. Asante, C. Petersen, T. Kocis, H.E. Dahlke, and T. Harter, 2019. An integrated approach toward sustainability via groundwater banking in the southern Central Valley, California. Water Resources Research, 55. doi:10.1029/2018WR024069. (pdf file for personal use only)
Harter, T., T. Moran, and E. Wildman, 2019. Adjudicating Groundwater – A Judge’s Guide to Understanding Groundwater and Modeling. Dividing The Waters. The National Judicial College, Reno, NV 89557. 95 pages.
Hanak, E., A. Escriva-Bou, B. Gray, S. Green, T. Harter, J. Jezdimirovic, J.R. Lund, J. Medellín-Azuara, P. Moyle, N. Seavy. 2019. Water and the Future of the San Joaquin Valley. Final Report, Public Policy Institute of California, San Francisco, California, 100 p. (open access)
Drummond, J.D., F. Boano, E.R. Atwill, X. Li, T. Harter, and A.I. Packman, 2018. Cryptosporidium oocyst persistence in agricultural streams - a mobile-immobile model framework assessment. Nature Scientific Reports Vol 8, Article 4603. doi:10.1038/s41598-018-22784-x
Mount, J., E. Hanak et al., 2018. Managing Drought in a Changing Climate: Four Essential Reforms. Public Policy Institute of California Report, 30 p.
Ransom, K.M., A.M. Bell, Q.E. Barber, G. Kourakos, and T.Harter, 2018. A Bayesian approach to infer nitrogen loading rates from crop and land-use types surrounding private wells in the Central Valley, California. Hydrol. Earth Syst. Sci., 22:2739-2758, 2018, doi:10.5194/hess-22-2739-2018.
Cantor, A., D. Owen, T. Harter, N. G. Nylen, and M. Kiparsky, 2018. Navigating Groundwater-Surface Water Interactions under the Sustainable Groundwater Management Act, Center for Law, Energy & the Environment, UC Berkeley School of Law, Berkeley, CA. 50 pp., https://doi.org/10.15779/J23P87
Foglia, L., J. Neuman, D.G. Tolley, S.B. Orloff, R.L. Snyder, and T. Harter, 2018. Modeling guides groundwater management in a basin with river-aquifer interactions. California Agriculture 72:1, 84-95.
Diamantopoulos, E., J. Simunek, C. Oberdoerster, K. Hammel,B. Jene, T. Schroeder, and T. Harter, 2017. Assessing the potential exposure of groundwater to pesticides: A model comparison. Vadose Zone J. 16(11), 13 pages, doi:10.2136/vzj2017.04.0070.
Harter, T., K. Dzurella, G. Kourakos, A. Hollander, A. Bell, N. Santos, Q. Hart, A.King, J. Quinn, G. Lampinen, D. Liptzin, T. Rosenstock, M. Zhang, G.S. Pettygrove, and T. Tomich, 2017. Nitrogen Fertilizer Loading to Groundwater in the Central Valley. Final Report to the Fertilizer Research Education Program, Projects 11-0301 and 15-0454, California Department of Food and Agriculture and University of California Davis, 325p.
Ransom, K.M., B.T. Nolan, J.A. Traum, C.C. Faunt, A.M. Bell, J.M. Gronberg, D.C. Wheeler, C.Z. Rosecrans, B.Jurgens, G.E. Schwarz, K. Belitz, S.M. Eberts, G. Kourakos, and T. Harter, 2017. A hybrid machine learning model to predict and visualize nitrate concentration throughout the Central Valley aquifer, California, USA, Science of The Total Environment, Volumes 601–602 (1), p. 1160-1172, doi:10.1016/j.scitotenv.2017.05.192 (open access).
Hanak, E., J. Lund, B. Arnold, A. Escriva-Bou, B. Gray, S. Green, T. Harter, R. Howitt, D. MacEwan, J. Medellín-Azuara, P. Moyle, and N. Seavy, 2017. Water Stress and a Changing San Joaquin Valley, Public Policy Institute of California Report, 50p. (open access).
Ludington, W.B., T.D. Seher, O. Applegate, X. Li, J.I. Kliegman, C. Langelier, E.R. Atwill, T. Harter, and J.L. DeRisi, 2017. Assessing biosynthetic potential of agricultural groundwater through metagenomic sequencing: A diverse anammox community dominates nitrate-rich groundwater. PloS one, 12(4), p.e0174930 (open access).
Baram, S., V. Couvreur, T. Harter, M. Read, P.H. Brown, M. Kandelous, D.R. Smart, and J.W. Hopmans, 2016. Estimating Nitrate Leaching to Groundwater from Orchards: Comparing Crop Nitrogen Excess, Deep Vadose Zone Data-Driven Estimates, and HYDRUS Modeling. Vadose Zone J. 15. doi:10.2136/vzj2016.07.0061 (open access).
Ransom, K. M., M. N. Grote, A. Deinhart, G. Eppich, C. Kendall, M. E. Sanborn, A. K. Souders, J. Wimpenny, Q.-Z. Yin, M. Young, and T. Harter, 2016. Bayesian nitrate source apportionment to individual groundwater wells in the Central Valley by use of elemental and isotopic tracers, Water Resour. Res., 52, 5577–5597, doi:10.1002/2015WR018523 (open access).
Diamantopoulos, E., W. Durner, T. Harter, Prediction of capillary air-liquid interfacial area vs. saturation function from relationship between capillary pressure and water saturation, Advances in Water Resources, Volume 97, November 2016, Pages 219-223, ISSN 0309-1708, doi:10.1016/j.advwatres.2016.09.012.
Hafner, S. C., N. Watanabe, . Harter, B. A. Bergamaschi, S. J. Parikh, 2016. Effects of solid-liquid separation and storage on monensin attenuation in dairy waste management systems, Journal of Environmental Management, Volume 190, 1 April 2017, Pages 28-34, ISSN 0301-4797, doi:10.1016/j.jenvman.2016.12.024.
Edwards, E. C., Harter, T., Fogg, G. E., Washburn, B., & Hamad, H. (2016). Assessing the Effectiveness of Drywells as Tools for Stormwater Management and Aquifer Recharge and Their Groundwater Contamination Potential. Journal of Hydrology 539:539-553, doi:10.1016/j.jhydrol.2016.05.059.
Baram S., V. Couvreur, T. Harter, M. Read, P.H. Brown, J.W. Hopmans, D.R. Smart, 2016. Assessment of orchard N losses to groundwater with a vadose zone monitoring network. Agricultural Water Management 172:83-95. doi:10.1016/j.agwat.2016.04.012
Hafner, S.C., T. Harter, and S.J. Parikh, 2016. Evaluation of monensin transport to shallow groundwater after irrigation with dairy lagoon water. J. Env. Qual. 45(2):480-487. doi:10.2134/jeq2015.05.0251
Harter, T., 2015. California's agricultural regions gear up to actively manage groundwater use and protection. California Agriculture 69(3):193-201, doi:10.3733/ca.E.v069n03p193 (open access)
Li, X., E.R. Atwill, E. Antaki, O. Applegate, B. Bergamaschi, R.F. Bond, J. Chase, K.M. Ransom, W. Samuels, N. Watanabe, and T. Harter, 2015. Fecal indicator and pathogenic bacteria and their antibiotic resistance in alluvial groundwater of an irrigated agricultural region with dairies. J. Env. Qual. 44:1435-1447, doi: 10.2134/jeq2015.03.0139 (open access)
Bradford, S.A., J. Schijven, and T. Harter, 2015. Microbial transport and fate in the subsurface environment: Introduction to the special section. J. Env. Qual. 44:1333-1337, doi: 10.2134/jeq2015.07.0375.
Medellin-Azuara, J., D. MacEwan, R.E. Howitt, G. Kourakos, E.C. Dogrul, C.F. Brush, T.N. Kadir, T. Harter, F. Melton, J.R. Lund, 2015. Hydro-economic analysis of groundwater pumping for irrigated agriculture in California's Central Valley, USA. Hydrogeology J., DOI 10.1007/s10040-015-1283-9, 12 p. (published online)
O'Geen, T., M.B.B. Saal, H.E. Dahlke, D.A. Doll, R.B. Elkins, A. Fulton, G.E. Fogg, T. Harter, J.W. Hopmans, C. Ingels, F.J. Niederholzer, S. Sandoval-Solis, P.S. Verdegaal, M. Walkinshaw, 2015. Soil suitability index identifies potential areas for groundwater banking on agricultural lands. California Agriculture 69(2):75-84, doi: 10.3733/ca.v069n02p75 (open access).
Mayzelle, M. M., J. H. Viers, J. Medellin-Azuara, and T. Harter, 2015. Economic feasibility of irrigated agricultural land use buffers to reduce groundwater nitrate in rural drinking water sources. Water 7(1):12-37, doi: 10.3390/w7010012 (open access).
Dzurella, K.N., G. S. Pettygrove, A. Fryjoff-Hung, A. Hollander, and T. Harter, 2015. Potential to assess nitrate leaching vulnerability of irrigated cropland. J. Soil and Water Conservation 70(1):63-72, doi: 10.2489/jswc.70.1.63 (open access).
Ledesma-Ruiz, R., E. Pasten-Zapata, R. Parra, T. Harter, and J. Mahlknecht. Investigation of the geochemical evolution of groundwater under agricultural land: A case study in northeastern Mexico. J. Hydrology, 521: 410-423, doi: 10.1016/j.jhydrol.2014.12.026 (open access).
Pasten-Zapata, E., R. Ledesma-Ruiz, T. Harter, A. I. Ramirez, J. Mahlknecht, 2014. Assessment of sources and fate of nitrate in shallow groundwater of an agricultural area by using a multi-tracer approach. Sci. Tot. Environ. 470-471:855-864, doi:10.1016/j.scitotenv.2013.10.043 (open access).
Harter, T. and H. Dahlke, 2014. Out of sight, but not out of mind: California refocuses on groundwater. California Agriculture 68(3):54-55. doi:10.3733/ca.v068n03p54 (open access).
Kourakos, G., and T. Harter, 2014. Parallel simulation of groundwater non-point source pollution using algebraic multigrid preconditioners. Comput. Geosci. 18(5):851-867, doi:10.1007/s10596-014-9430-2.
Rosenstock, T. S., D. Liptzin, K. Dzurella, A. Fryjoff-Hung, A. Hollander, V. Jensen, A. King, G. Kourakos, A. McNally, G. S. Pettygrove, J. Quinn, J. H. Viers, T. P. Tomich, and T. Harter, 2014. Agriculture's contribution to nitrate contamination of Californian groundwater (1945-2005), J. Env. Qual. 43(3):895-907, doi:10.2134/jeq2013.10.0411 (open access).
Harter, T., N. Watanabe, X. Li, E. R. Atwill, and W. Samuels, 2014. Microbial groundwater sampling protocol for fecal-rich environments, Groundwater, doi:10.1111/gwat12222 (open access).
Liang, X. Q., T. Harter, L. Porta, C. van Kessel, and B. A. Linquist, 2014. Nitrate leaching in Californian rice fields: A field- and regional-scale assessment, J. Env. Qual. 43(3):881-894, doi:10.2134/jeq2013.10.0402.
Kourakos, G. and T. Harter, 2014. Vectorized simulation of groundwater flow and streamline transport. Environmental Modelling & Software 52:207-221, doi:10.1016/j.envsoft.2013.10.029.
Foglia, L., A. McNally, and T. Harter, 2013. Coupling a spatio-temporally distributed soil water budget with stream-depletion functions to inform stakeholder-driven management of groundwater-dependent ecosystems. Water Resour. Res. 49:7292-7310, doi:10.1002/wrcr.20555 (open access).
Li, X., N. Watanabe, C. Xiao, T. Harter, B. McCowan, Y. Liu, E. R. Atwill, 2013. Antibiotic-resistant E. coli in surface water and groundwater in dairy operations in Northern California. Environ. Monit. Assess, doi:10.1007/s10661-013-3454-2 (pdf file for personal use only)
Lockhart, K.M., A. M. King, T. Harter, 2013. Identifying sources of groundwater nitrate contamination in a large alluvial groundwater basin with highly diversified intensive agricultural production. J. Contam. Hydrol. 151:140-154, doi:10.1016/j.jconhyd.2013.05.008 (pdf file for personal use only).
Harter T. and H. Morel-Seytoux, 2013. Peer Review of the IWFM, MODFLOW and HGS Model Codes: Potential for Water Management Applications in California’s Central Valley and Other Irrigated Groundwater Basins. Final Report, California Water and Environmental Modeling Forum, August 2013, Sacramento, 58 pages. http://www.cwemf.org.
Gold, A., D. Parker, R. Waskom, J. Dobrowolski, M. O’Neill, P. Groffman, and K. Addy with contributing authors:M. Barber, S. Batie, B. Benham, M. Bianchi, T. Blewett, C. Evenson, K. Farrell-Poe, C. Gardner, W. Graham, J. Harrison, T. Harter, J. Kushner, R. Lowrance, J. Lund, R. Mahler, M. McClaron, M. McFarland, D. Osmond, J. Pritchett, L. Prokopy, C. Rock, A. Shober, M. Silitonga, D. Swackhamer, J. Thurston, D. Todey, R. Turco, G. Vellidis, and L.Wright Morton, 2013. Advancing water resource management in agricultural, rural, and urbanizing watersheds: Enhancing university involvement, Journal of Soil and Water Conservation 68(4):337-348, doi:10.2489/jswc.68.4.337 (pdf file for personal use only).
Medellin, J., T.S. Rosenstock, R.E. Howitt, T. Harter, K.K. Jessoe, K. Dzurella, G.S. Pettygrove, J.R. Lund, 2013. Agro-economic analysis of nitrate crop source reductions. J. Water Resources Planning and Mgmt. 139(5):501-511, doi:10.1061/(ASCE)WR.1943-5452.0000268. (pdf file for personal use)
Botros, F.E., Y.S. Onsoy, T.R. Ginn, and T. Harter, 2012. Richards equation-based modeling to estimate flow and nitrate transport in a deep alluvial vadose zone, Vadose Zone Journal Vol. 11(4), doi:10.2136/vzj2011.014 (free public access).
Park, Y., E.R. Atwill, L.L. Hou, A.I. Packman, and T. Harter, 2012. Deposition of Cryptosporidium parvum oocysts in porous media: A synthesis of attachment efficiencies measured under varying environmental conditions. Env. Sci. Tech. 46 (17), pp. 9491–9500, doi:10.1021/es300564w (free public access).
Kourakos, G., F. Klein, and T. Harter, 2012. A GIS-linked unit response function approach to stochastic groundwater nonpoint source pollution modeling, Models - Repositories of Knowledge, IAHS Publications (Red Book Series #355), 2013. 8 pages.
Bremer, J. and T. Harter, 2012. Domestic wells have high probability of pumping septic tank leachate, Hydrol. Earth Sys. Sci 16:2453-2467, doi:10.5194/hess-16-2453-2012 (free public access).
Webster, J.P., S.C. Kover, R.J. Bryson, T. Harter, D.S. Mansell, D.L. Sedlak, 2012. Occurrence of Trenbolone acetate metabolites in simulated confined animal feeding operation (CAFO) runoff, Env. Sci. Tech. 46(7):3803-3810, doi:10.1021/es204529v.
Unc, A., M. J. Goss, S. Cook, X. Li, E. R. Atwill, and T. Harter, 2012. Analysis of matrix effects critical to microbial transport in organic waste-affected soils across laboratory and field scales. Water Resour. Res. 48, W00L12, 17p., doi:10.1029/2011WR010775.
Kourakos, G., F. Klein, A. Cortis, and T. Harter, 2012, A groundwater nonpoint source pollution modeling framework to evaluate long-term dynamics of pollutant exceedance probabilities in wells and other discharge locations,Water Resour. Res., 48, W00L13, doi:10.1029/2011WR010813.
Harter, T., J. R. Lund, J. Darby, G. E. Fogg, R. Howitt, K. K. Jessoe, G. S. Pettygrove, J. F. Quinn, J. H. Viers, D. B. Boyle, H. E. Canada, N. DeLaMora, K. N. Dzurella, A. Fryjoff-Hung, A. D. Hollander, K. L. Honeycutt, M. W. Jenkins, V. B. Jensen, A. M. King, G. Kourakos, D. Liptzin, E. M. Lopez, M. M. Mayzelle, A. McNally, J. Medellin-Azuara, and T. S. Rosenstock, 2012. Addressing Nitrate in California's Drinking Water With A Focus on Tulare Lake Basin and Salinas Valley Groundwater, Report for the State Water Resources Control Board Report to the Legislature, Center for Watershed Sciences, University of California, Davis, 87p.
Viers, J.H., Liptzin, D., Rosenstock, T.S., Jensen, V.B., Hollander, A.D., McNally, A., King, A.M., Kourakos, G., Lopez, E.M., De La Mora, N., Fryjoff-Hung, A., Dzurella, K.N., Canada, H.E., Laybourne, S., McKenney, C., Darby, J., Quinn, J.F. & Harter, T., 2012. Nitrogen Sources and Loading to Groundwater. Technical Report 2, 323p., in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis. (free public access).
Dzurella, K.N., Medellin-Azuara, J., Jensen, V.B., King, A.M., De La Mora, N., Fryjoff-Hung, A., Rosenstock, T.S., Harter, T., Howitt, R., Hollander, A.D., Darby, J., Jessoe, K., Lund, J.R., & Pettygrove, G.S., 2012. Nitrogen Source Reduction to Protect Groundwater Quality. Technical Report 3, 174p., in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis, (free public access).
Boyle, D., King, A., Kourakos, G., Lockhart, K., Mayzelle, M., Fogg, G.E. & Harter, T., 2012. Groundwater Nitrate Occurrence. Technical Report 4, 277p., in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake
Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis (free public access).
King, A., Jensen, V., Fogg, G.E. & Harter, T., 2012. Groundwater Remediation and Management for Nitrate. Technical Report 5, 50p., in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis (free public access).
Canada, H.E., Harter T., Honeycutt, K., Jessoe, K., Jenkins, M.W. & Lund, J.R., 2012. Regulatory and Funding Options for Nitrate Groundwater Contamination. Technical Report 8, 91p., in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis (free public access)
Mansell, D. S., R. J. Bryson, T. Harter, J. P. Webster, E. P. Kolodziej, and D. Sedlak, 2011. Fate of endogenous steroid hormones in steer feedlots under simulated rainfall-induced runoff, Env. Sci. and Technol. 45 (20), pp. 8811–8818, doi:10.1021/es202072f.
Strauss, C., T. Harter, M. Radke, 2011. Effects of pH and manure on transport of sulfonamide antibiotics in soil, J. of Env. Quality 40:1652–1660, doi:10.2134/jeq2010.0535.
Corbett, F., T. Schetrit, and T. Harter, 2011. Crop Water Use, Groundwater Flow, and Subsidence at Naval Air Station Lemoore, Fresno and Kings County, California, Final Report, University of California, Davis, 353 p.
Watanabe, N., B. A. Bergamaschi, K. A. Loftin, M. T. Meyer, and T. Harter, 2010. Use and environmental occurrence of antibiotics in freestall dairy farms with manure forage fields, Environ. Sci. Technol., 2010, 44 (17): 6591–6600, doi:10.1021/es100834s. (free public access).
Gutierrez, I. R., N. Watanabe, T. Harter, B. Glaser, and M. Radke, 2010. Effect of sulfonamide antibiotics on microbial diversity and activity in a Californian Mollic Haploxeralf, J. Soils and Sediments 10(3): 537-544, doi: 10.1007/s11368-009-0168-8. (pdf file for personal use only).
Megdal, S. B., R. Hamann, T. Harter, J. W. Jawitz, J. M. Jess, 2009. Water, People, and the Future: Water Availability for Agriculture in the United States, Council for Agricultural Science and Technology, Issue Paper 44 (free public access), 20 p.
VanderSchans, M. L., T. Harter, A. Leijnse, M. C. Mathews, R. D. Meyer, 2009. Characterizing sources of nitrate leaching from an irrigated dairy farm in Merced County, California, J. of Contam. Hydrology 110:9-21, (pdf file for personal use only).
Harter, T., 2009. Agricultural impacts on groundwater nitrate, Southwest Hydrology 8(4):21-23 (Jul/Aug 2009) . (free public access)
Botros, F. E., T. Harter, Y. S. Onsoy, A. Tuli, J. W. Hopmans, 2009. Spatial variability of hydraulic properties and sediment characteristics in a deep alluvial unsaturated zone. Vadose Zone Journal 8:276–289 doi:10.2136/vzj2008.0087 (free public access)
Vereecken, H., T. Kamai, T. Harter, R. Kasteel, J. W. Hopmans, J. A. Huisman, and J. Vanderborght, 2008. Comment on “Field observations of soil moisture variability across scales” by James S. Famiglietti et al., Water Resour. Res., 44, W12601, doi:10.1029/2008WR006911. (pdf file for personal use only)
Watanabe, N., T. Harter, and B. A. Bergamaschi, 2008. Environmental occurrence and shallow groundwater detection of the antibiotic Monensin from dairy farms. J. Environ. Qual. 37:S-78–S-85 (2008). doi:10.2134/jeq2007.0371. (pdf file for personal use only)
Harter, T. and L. Rollins (eds.), 2008. Watersheds, Groundwater, and Drinking Water - A Practical Guide. University of California Agriculture and Natural Resources Publication 3497. 274pp.
Rains, M.C., R. A. Dahlgren, G. E. Fogg, T. Harter, and R. J. Williamson, 2008. Geological control of physical and chemical hydrology in California vernal pools. Wetlands 28(2):347-362. (pdf file for personal use only)
Chomycia, J.C., P.J. Hernes, T. Harter, and B.A. Bergamaschi, 2008. Land management impacts on dairy-derived dissolved organic carbon in ground water. J. Env. Qual. 37(2), 333-343. doi:10.2134/jeq2007.0183.
Harter, T., E.R. Atwill, L.L. Hou, B.M. Karle, and K.W. Tate, 2008. Developing risk models of Cryptosporidium transport in soils from vegetated, tilted soilbox experiments. J. Env. Qual. 37(1), 245-258. doi:10.2134/jeq2006.0281.(pdf file for personal use only)
Young, C., W. Wallender, G. Schoups, G. Fogg, B. Hanson, T. Harter, J. Hopmans, R. Howitt, T. Hsiao, S. Panday, K. Tanji, S. Ustins, K. Ward, 2007. Modeling shallow water table evaporation in irrigated regions. J. Irrigation Drainage Systems, 21(2):119-132. doi:10.1007/s10795-007-9024-4.
Vereecken, H., T. Kamai, T. Harter, R. Kasteel, J. Hopmans, and J. Vanderborght, 2007. Explaining soil moisture variability as a function of mean soil moisture: A stochastic unsaturated flow perspective, Geophys. Res. Lett., 34, L22402, doi:10.1029/2007GL031813.
Harter, T. (ed.), 2007. Groundwater Quality Protection: Managing Dairy Manure in the Central Valley of California. University of California Agriculture and Natural Resources Publication 9004, 178 pp.
Singleton, M. J., B. K. Esser, J. E. Moran, G. B. Hudson, W. W. McNab, and T. Harter, 2007. Saturated zone denitrification: Potential for natural attenuation of nitrate contamination in shallow groundwater under dairy operations. Env. Sci. & Technol. 41 (3), 759-765.
Vereecken, H., R. Kasteel, J. Vanderborght, and T. Harter. 2007. Upscaling hydraulic propertes and soil water flow processes in heterogeneous soils: a review. Vadose Zone Journal 6(1), 1-28. doi:10.2136/vzj2006.0055
Cortis, A., T. Harter, L. L. Hou, E. R. Atwill, A. I. Packman, P. G. Green, 2006. Transport of Cryptosporidium parvum in porous media: Long-term elution experiments and continuous time random walk filtration modeling. Water Resour. Res. 42(12), W12S13, doi:10.1029/2006WR004897.
Marques. G. F., J. R. Lund, M. R. Leu, M. Jenkins, R. Howitt, T. Harter, S. Hatchett, N. Ruud, and S. Burke, 2006. Economically driven simulation of regional water systems: Friant-Kern, California. J. Water Resour. Planning and Mgmt 132(6):468-479. doi:10.1061/(ASCE)0733-9496(2006)132:6(468)
Zhang, H., T. Harter, and B. Sivakumar, 2006. Nonpoint source solute transport normal to aquifer bedding in heterogeneous, Markov chain random fields, Water Resour. Res., Vol. 42, No. 6, W06403, doi 10.1029/2004WR003808 .
Cable-Rains, M., G. E. Fogg, T. Harter, R. A. Dahlgren, and R. J. Williamson, 2006. The role of perched aquifers in hydrological connectivity and biogeochemical processes in vernal pool landscapes, Central Valley, California. Hydrol. Process. 20, 1157–1175. (pdf file for personal use only)
Searcy, K.E., A. I. Packman, E. R. Atwill, and T. Harter, 2006. Deposition of Cryptosporidium oocysts in streambeds. Applied and Environmental Microbiology, 72(3):1810-1816. (pdf file for personal use only)
Chang, A., T. Harter, J. Letey, D. Meyer, R. D. Meyer, M. Campbell-Mathews, F. Mitloehner, S. Pettygrove, P. Robinson, R. Zhang, 2006. Managing Dairy Manure in the Central Valley of California; University of California Committee of Experts on Dairy Manure Management Final Report to the Regional Water Quality Control Board, Region 5, Sacramento, June 2005. 178 pp. (pdf file for personal use only)
Harter, T., 2005, Finite-size scaling analysis of percolation in three-dimensional correlated binary Markov chain random fields, Physical Review E 72(2), 26120 (8 pages), doi: 10.1103/PhysRevE.72.026120. (pdf file for personal use only)
Harter, T., Y. S. Onsoy, K. Heeren, M. Denton, G. Weissmann, J. W. Hopmans, W. R. Horwath, 2005. Deep vadose zone hydrology demonstrates fate of nitrate in eastern San Joaquin Valley, California Agriculture 59(2):124-132. (pdf file for personal use only)
Searcy, K. E., A. Packman, E. R. Atwill, and T. Harter, 2005. Association of Cryptosporidium parvum with Suspended Particles: Impact on Oocyst Sedimentation, Applied and Environmental Microbiology 71(2):1072-1078. (pdf file for personal use only)
Sivakumar, B., T. Harter, and H. Zhang, 2005. Solute transport in a heterogeneous aquifer: A search for nonlinar deterministic dynamics, Nonlinear Processes in Geophysics 12(2):211-218. (pdf file for personal use only)
Sivakumar, B., T. Harter, H. Zhang, 2005. A fractal investigation of solute travel time in a heterogeneous aquifer: Transition probability/Markov chain representation, Ecological Modelling 182:355-370. (pdf file for personal use only)
Onsoy, Y. S., T. Harter, T. R. Ginn, W. R. Horwath, 2005. Spatial variability and transport of nitrate in a deep alluvial vadose zone. Vadose Zone J. 4:41-55. (pdf file for personal use only)
Harter, T. and J. Menke, 2005. Cow numbers and water quality - is there a magic number? A groundwater perspective. (revised from: Harter T., 2004, Proceedings, National Alfalfa Symposium, San Diego, December 13-15, 2004. 13 pages). (pdf file for personal use only)
Harter, T. and S. Talozi, 2004. A simple, inexpensive dialysis sampler for small diameter monitoring wells, Ground Water Monitoring & Remediation, Fall 2004, 97-105. doi:10.1111/j.1745-6592.2004.tb01307.x (pdf file for personal use only)
Harter, T., C. Knudby, 2004. Effective conductivity of periodic media with cuboid inclusions. Advances in Water Resources 27(10):1017-1032. (pdf file for personal use only)
Harter, T. and J. W. Hopmans, 2004. Role of Vadose Zone Flow Processes in Regional Scale Hydrology: Review, Opportunities and Challenges. In: Feddes,R.A., G.H. de Rooij and J.C. van Dam, Unsaturated Zone Modeling: Progress, Applications, and Challenges, (Kluwer, 2004), p. 179-208. (pdf file for personal use only).
Kolodziej, E. P., T. Harter, D. L. Sedlak, 2004. Dairy wastewater, aquaculture, and spawning fish as sources of steroid hormones in the aquatic envionrment, Env. Science and Technol. 38, p. 6377-6384. (pdf file for personal use only)
Ruud, N. C., T. Harter, and A. W. Naugle, 2004. Estimation of groundwater pumping as closure to the water balance of a semi-arid irrigated agricultural basin. J. Hydrology 297:51-73. (pdf file for personal use only)
Nakamura, K., T. Harter, Y. Hirono, H. Horino, and T. Mitsuno, 2004. Assessment of root zone nitrogen leaching as affected by irrigation and nutrient management practices. Vadose Zone J. 3:1353–1366. (pdf file for personal use only)
Vrugt, J. A., G. H. Schoups, J. W. Hopmans, C. Young, W. W. Wallender, T. Harter, W. Bouten. 2004. Inverse modeling of large-scale spatially-distributed vadose zone properties using global optimization, Water Resour. Res. Vol. 40, No. 6, W06503 10.1029/2003WR002706.
Minasny, B., J. W. Hopmans, T. Harter, S. O. Eching, A. Tuli, M. A. Denton, 2004. Neural networks prediction of soil hydraulic functions for alluvial soils using multistep outflow data, Soil Science Soc. Of Am. Journal 68:417-429.
Harter, T., 2004. Aquifers / Specific yield storage equation / Vulnerability mapping of groundwater resources / Animal farming operations: groundwater quality issues. Wiley Encyplopedia of Water, 2005.
Independent Panel on Appropriate Measurement of Agricultural Water Use, Convened by the California Bay-Delta Authority, Final Report, September 2003.
Wang, Z., L. Wu, T. Harter, J. Lu, W. A. Jury, 2003. A field study of unstable preferential flow during soil water redistribution, Water Resour. Res. 39(4), 10.1029/2001WR000903, 01 April 2003.
Ruud, N. C., T. Harter, A. W. Naugle, 2002. A conjunctive use model for the Tule groundwater sub-basin area in the Southern-Eastern San Joaquin Valley, California, Final Report to the U.S. Bureau of Reclamation, November 2002, 196 pages. (pdf file for personal use only)
Atwill, E. R., L. Hou, B. M. Karle, T. Harter, K. W. Tate, R. A. Dahlgren, 2002. Transport of Cryptosporidium parvum oocysts through vegetated buffer strips and estimated filtration efficiency, Applied and Environmental Microbiology 68(11), pp. 5517-5527. (pdf file for personal use only)
Harter, T., H. Davis, M. C. Mathews, R. D. Meyer, 2002. Shallow groundwater quality on dairy farms with irrigated forage crops, Journal of Contaminant Hydrology 55 (3-4), pp. 287-315. (pdf file for personal use only)
Harter T., 2002. Stochastic analysis of reactive transport in heterogeneous porous media, in: Govindaraju, R. S. (ed.), Stochastic Methods in Subsurface Contaminant Hydrology, American Society of Civil Engineers, pp. 89-167.
Wang, Z., J. Lu, L. Wu, T. Harter, W. A. Jury, 2002. Visualizing preferential flow paths using ammonium carbonate and a pH-Indicator, Soil Sci. Soc. Of America J., Vol. 66, pp.347–351.
Ruud, N. C., T. Harter, A. W. Naugle, 2002. A conjunctive use groundwater-surface water flow model for the Tule River groundwater basin in the eastern-central San Joaquin Valley, California; in: Marino, M. A. & S. P. Simonovic, Integrated Water Resources Management, IAHS Publication No. 272, pp. 167-174.
Harter, T., R. D. Meyer, M. C. Mathews, 2002. Nonpoint source pollution from animal farming in semi-arid regions: Spatio-temporal variability and groundwater monitoring strategies; in: Ribeiro, L. (Ed.), 2002, Future Groundwater Resources at Risk, Proceedings of the 3rd International Conference, Lisbon, Portugal, June 2001; pp. 363-372. (pdf file for personal use only)
Harter, T., K. Heeren, and W. R. Horwath. 2002. Nitrate distribution in a deep, alluvial unsaturated zone: Geologic control vs. fertilizer management. Proceedings, 2002 California Plant and Soil Conference, February 5-6, 2002, Fresno, CA, pp. 73-83 (pdf file for personal use only)
Mathews, M. C., E. Swenson, T. Harter, R. D. Meyer, 2001. Matching dairy lagoon nutrient application to crop nitrogen uptake using a flow meter and control valve. ASAE Paper Number 01-2105, 2001 ASAE Annual International Meeting, Sacramento, CA, July 30-August 1, 2001. (pdf file for personal use only)
Harter, T., M. C. Mathews, R. D. Meyer, 2001. Effects of dairy manure nutrient management on shallow groundwater nitrate: a case study. ASAE Meeting Presentation, ASAE Paper Number 01-2192, 2001 ASAE Annual International Meeting, Sacramento, CA, July 30-August 1, 2001; 2001. (pdf file for personal use only)
Tuli, A., M.A. Denton, J.W. Hopmans, T. Harter, and J.L. Mac Intyre. 2001. Multi-step outflow experiment: From soil preparation to parameter estimation . Hydrology program, Dept of Land, Air, and Water Resources, University of California, Davis, CA, Paper number 100037. (pdf file for personal use only)
Harter, T., H. Davis, M. C. Mathews, R. D. Meyer, 2001. Monitoring shallow groundwater nitrogen loading from dairy facilities with irrigated forage crops. ASAE Meeting Presentation, ASAE Paper Number 01-2103, 2001 ASAE Annual International Meeting, Sacramento, CA, July 30-August 1, 2001. (pdf file for personal use only)
Harter, T., S. Wagner, E. R. Atwill, 2000. Colloid transport and filtration of Cryptosporidium parvum in sandy soils and aquifer sediments, Env. Science and Technology, 34(1), pp. 62-70. (pdf file and pdf-supplement for personal use only)
Harter, T., 2000. Application of stochastic theory in groundwater contamination risk analysis: Suggestions for the consulting geologist/engineer, Theory, Modeling and Field Investigation in Hydrogeology: A special volume in honor of S. P. Neuman's 60th Birthday, Special Book Series, Geological Society of America Paper 348, pp. 43-52.
Ruud, N. C., A. W. Naugle, T. Harter, 1999. A GIS-linked conjunctive use groundwater-surface water flow model for the Tule River basin, southeastern San Joaqin Valley, California, Proceedings, International Conference on Calibration and Reliability in Groundwater Modeling, Zuerich, Switzerland, 20-23 Sept. 1999, pp. 739-744.
Brune, D. E., C. M. Drapcho, D. E. Radcliff, T. Harter, R. Zhang, 1999. Electromagnetic survey to rapidly assess water quality in agricultural watersheds, ASAE Paper No. 99-2176 ASAE 1999Annual International Meeting, ASAE, 2950 Niles Rd., St. Joseph, MI 49085-9659.
Ruud, N. C., T. Harter, 2000. Conditional geostatistical model of alluvial hydrofacies for risk analysis of deep groundwater quality deterioration from shallow salinity, Post-Conference Proceedings, International Conference on Calibration and Reliability in Groundwater Modeling, Zuerich, Switzerland, 20-23 Sept. 1999, IAHS Publication No. 265, Oxfordshire, UK.
Harter T., R. D. Meyer, M. Campbell-Mathews, 1999, Shallow groundwater quality under dairies in Merced and Stanislaus County, Proceedings, 1999 California Plant and Soil Conference, California Chapter of American Society of Agronomy, pp. 122-127.
Campbell-Mathews, M., R. D. Meyer, T. Harter, 1999. Using dairy lagoon water to replace commercial fertilizer, Proceedings, 1999 California Plant and Soil Conference, California Chapter of American Society of Agronomy, pp. 133-138.
Harter, T., and D. Zhang, 1999. Water flow and solute spreading in heterogeneous soils with spatially variable water content, Water Resour. Res. 35(2), pp. 415-426.
Harter, T., T.C.J. Yeh, 1998. Flow in unsaturated random porous media, nonlinear numerical analysis, and comparison to analytic stochastic models, Adv. in Water Resour. 22(3), pp. 257-272.
Harter, T., K. Heeren, G. Weissmann, W.R. Horwath, J. Hopmans, 1999. Field Scale Characterization of a Heterogeneous, Moderately Deep Vadose Zone: The Kearney Research Site, Proceedings, Characterization and Measurement of the Hydraulic Properties of Unsaturated Porous Media, United States Salinity Laboratory, Riverside, California, pp. 621-630.
Harter, T., S. Wagner, E.R. Atwill, 1998. Groundwater protection: The fate of Cryptosporidium parvum in porous media, Proceedings, Groundwater Quality: Remediation and Protection 1998, IAHS Publication No. 250, pp. 75-77.
Harter, T., 1998. Uncertainty and risk analysis of contaminant transport, Proceedings, California Biennial Groundwater Conference, Sacramento, September 14-15, 1997, University of California Water Resources Center Report No. 95, pp. 97-107.
Harter T., 1996. On the usefulness of analytical stochastic models for solute transport in heterogeneous, variably saturated soils, 1996 ASAE Annual International Meeting, Phoenix, Arizona, July 1996, ASAE, St. Joseph, Michigan 49085.
Harter T., A.L. Gutjahr, T.-C.J. Yeh, 1996. Linearized co-simulation of hydraulic conductivity, pressure head, and flux in saturated and unsaturated, heterogeneous porous media, J. of Hydrology, 183, pp. 169-190.
Harter, T., T.C.J. Yeh, 1996. Stochastic analysis of solute transport in heterogeneous, variably saturated porous media, Water Resour. Res.,32, pp. 1585-1595.
Harter, T., T.C.J. Yeh, 1996. Conditional stochastic analysis of solute transport in heterogeneous, variably saturated soils, Water Resour. Res., 32, pp. 1597 - 1609.
Harter, T., D. Zhang, 1995. Conditional prediction of transport in unsaturated, heterogeneous porous media: Monte Carlo simulation versus Eulerian-Lagrangian theory, in: Wagner, B.J., T.H. Illangasekare, K.H. Jensen (eds.), Models for assessing and monitoring groundwater quality, IAHS Publication No. 227, pp.193-201.
Harter T.., T.C.J. Yeh. 1993. An Efficient Method for Simulating Steady Unsaturated Flow in Random Porous Media: Using an Analytical Perturbation Solution as Initial Guess to a Numerical Model. Water Resources Research 29(12), pp. 4139-4149.
Yeh T.C.J., R. Srivastava, A. Guzman, Th. Harter. 1993. A Numerical Model for Water Flow and Chemical Transport in Variably Saturated Porous Media. Groundwater 31(4), pp. 634-644. doi:10.1111/j.1745-6584.1993.tb00597.x
Harter T., G. Teutsch. 1990. Pesticide Transport Models: Comparison and Validation with Soil Column Leaching Experiments. in: Weigman D.L.. 1990. "Pesticides in the Next Decade: The Challenge Ahead", Proceedings of the Third National Research Conference on Pesticides, November 8-9, 1990, Virginia Water Resources Research Center. pp.725-750. (pdf file for personal use only)
Shortcourses and Workshops Developed and Taught:
"Groundwater and Watersheds: An Introduction." 2-day short course. Sponsors/Coordinator: CA Groundwater Resources Association, University of California Cooperative Extension.
"Principles of Groundwater Flow and Transport Modeling." 3-day short course. Sponsors/Coordinator: CA Groundwater Resources Association, University of California Cooperative Extension.
"Introduction to Vadose Zone Hydrology." 3-day short course. Sponsor/Coordinator: CA Groundwater Resources Association and Cal/EPA Department of Toxic Substances Control.
"Groundwater, Wells, and Pumps: A Workshop for Growers." 1-day workshop. Sponsor/Coordinator: Local citizens groups, Cooperative Extension, Southern California Edison.
"Groundwater Quality Control and Monitoring on Dairies." 1/2-day workshop. Sponsor/Coordinator: University of California Cooperative Extension, Stanislaus and Tulare County.
"Drinking Water Source Assessment and Protection." 2-day short course. Sponsors/Coordinator: CA Groundwater Resources Association, CA Dept. of Health Services
"The Groundwater Workshop." 1-day workshop. Sponsor/Coordinator: The Water Awareness Committee of Monterey County, Inc.
"Applied Groundwater Hydrology: Principles, Measurements, and Interpretation." 2-day short course. Sponsor/Coordinator: Cal/EPA Department of Toxic Substances Control, CA Groundwater Resources Association and the University of California, Davis.