Sources of Nitrate & Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin Revised Report ACEPD AMEC Project No.: 6063050061 & 6063110206 February 2013 Table of Contents Executive Summary .................................................................................................................... ES-1 1.0 Introduction .............................................................................................................................. 1-1 1.1 Study Area ........................................................................................................................ 1-2 1.1.1 Surface Water Resources ........................................................................................ 1-2 1.1.2 Hydrogeology........................................................................................................... 1-2 1.2 Sources of Nitrate to the Santa Fe River and Springs ...................................................... 1-9 1.3 GIS Application ............................................................................................................... 1-11 1.4 Past and Projected Land Use ......................................................................................... 1-11 1.5 Groundwater Travel Time ............................................................................................... 1-12 2.0 Loading Estimation Methods and Information Sources ....................................................... 2-1 2.1 Land Use-Based Loadings ................................................................................................ 2-1 2.1.1 Inputs to Land Use-Based Loading Estimates ......................................................... 2-2 2.2 Domestic Wastewater ..................................................................................................... 2-10 2.2.1 Permitted Wastewater Facilities............................................................................. 2-10 2.2.2 Septic Systems ...................................................................................................... 2-11 3.0 Estimated Loadings of Nitrate to the Santa Fe Springsheds by Land Use and Source Type ......................................................................................................................................... 3-1 Uncertainty in Estimated Loadings ........................................................................................... 3-1 Source-Specific Uncertainties ........................................................................................... 3-2 Uncertainty in Groundwater Recharge Rates ................................................................... 3-4 4.0 Past and Projected Land Use and Effect on Nitrate Loading ............................................... 4-1 4.1 Past and Projected Land Use ........................................................................................... 4-1 4.2 Effect of Land Use Changes on Nitrate Loading to the Santa Fe Springsheds ................. 4-3 5.0 Groundwater Travel Time ........................................................................................................ 5-1 6.0 Summary ................................................................................................................................... 6-1 7.0 References ................................................................................................................................ 7-1 Attachment A Land Use Key List of Tables Table 1. Representative NO3-N Groundwater Concentrations Assigned by Land Use ................ 2-10 Table 2. Permitted Wastewater Facilities ...................................................................................... 2-11 Table 3. Estimated Nitrate Loadings to the Santa Fe River Springsheds in 2004 ........................... 3-1 Table 4. Land Use Changes from 1995 to 2004 ............................................................................. 4-2 Table 5. Rate of Change Projected from 2004 to 2030 ................................................................... 4-3 Table 6. Summary of Sources for Upper Floridan Aquifer Hydraulic Properties ............................. 5-2 List of Figures Figure 1. Project Locale.................................................................................................................. 1-3 Figure 2. Springsheds of the Santa Fe Basin ................................................................................. 1-7 Figure 3. Study Area ...................................................................................................................... 1-8 Figure 4. Nitrogen Cycle (USEPA, 2006a) .................................................................................... 1-9 Figure 5. 2004 Landuse for Santa Fe Springshed .......................................................................... 2-4 Figure 6. Portion of Springshed by Land Use Category ................................................................. 2-5 Figure 7. Recharge for Santa Fe Springshed ................................................................................. 2-6 Figure 8. Estimated Nitrate Loadings to the Santa Fe River Springsheds in 2004 ......................... 3-5 Figure 9. Projected Change in Land Use within the Santa Fe River Springshed 2004 - 2030 ....... 4-3 i AMEC Sources of Nitrate & Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin Revised Report ACEPD AMEC Project No.: 6063050061 & 6063110206 February 2013 Table of Contents (continued) List of Figures (continued) Figure 10. Estimated Past and Projected Nitrate Loadings ............................................................ 4-5 Figure 11. Area of Conduit Flow to Santa Fe River ........................................................................ 5-4 Figure 12. Horizontal Hydraulic Conductivity of the Upper Floridan Aquifer, Santa Fe Springshed .................................................................................................................... 5-5 Figure 13. Groundwater Travel Time to Santa Fe River Springs .................................................... 5-6 Figure 14. Groundwater Travel Time Less than 100 Years ............................................................ 5-7 List of Acronyms and Abbreviations % percent ACEPD Alachua County Environmental Protection Department AMEC AMEC Environment & Infrastructure, Inc. BMP Best Management Practices CAFOs concentrated animal feeding operations FAS Floridan aquifer system FDEP Florida Department of Environmental Protection FDOH Florida Department of Health FGS Florida Geological Survey FLUCCS Florida Land Use and Cover Classification System ft feet GIS Geographic Information Systems IAS Intermediate Aquifer System ICU Intermediate Confining Unit kg/ha/yr kilograms per hectare per year L liter lb pound MACTEC MACTEC Engineering and Consulting, Inc. mg/L milligrams per Liter MH mobile home MSL mean sea level MT metric ton (a metric ton is 1,000 kilograms or 2,205 pounds) MT/yr metric tons per year N/yr Nitrogen per year N2 Nitrogen gas - NO3 Nitrate NO3-N Nitrate nitrogen SDII SDII Global Corporation SFRS Santa Fe River/Springs SJRWMD St. Johns River Water Management District SRWMD Suwannee River Water Management District SWFWMD Southwest Florida Water Management District TMDL Total Maximum Daily Load TN total nitrogen UF IFAS University of Florida Institute of Food and Agricultural Sciences UFA Upper Floridan aquifer USGS United States Geological Survey WWTPs wastewater treatment plants ii AMEC Sources of Nitrate & Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin Revised Report ACEPD AMEC Project No.: 6063050061 & 6063110206 February 2013 Executive Summary The lower Santa Fe River has been determined by the Florida Department of Environmental Protection (FDEP) to be impaired for nutrients and dissolved oxygen, with a Total Maximum Daily Load (TMDL) target of 0.35 milligrams per liter (mg/L) of nitrate (NO3) to protect aquatic ecosystems. At the request of the Alachua County Environmental Protection Department (ACEPD) and to facilitate prioritization of local initiatives for springs protection for the lower Santa Fe River, MACTEC Engineering and Consulting, Inc. (MACTEC now AMEC), developed an ArcGIS™ tool designed to estimate nitrate loadings to groundwater in the springsheds. MACTEC also conducted an evaluation of the sources of nitrogen based on land use and loading rates and modeled groundwater travel time in the upper Floridan aquifer. Best available data, 2004 water management district land use land cover, were used for the project. The study area boundaries were the springsheds that were developed from those determined by SDII (2011) in their initial 2007-2008 work with modifications that focused on areas of known conduit flow. The Santa Fe River springsheds include parts of seven counties and three water management districts and cover approximately 550,000 acres (860 square miles). Groundwater recharge rates in the springsheds were determined by application of the MegaModel developed by the US Geological Survey to simulate groundwater flow in peninsular Florida. Sources of nitrate loading to the groundwater in the springsheds are introduced from point and non- point sources. Two distinct approaches were used to estimate nitrate loadings to groundwater depending on source type. Point sources include disposal of domestic wastewater by septic systems and permitted wastewater treatment plants, while non-point sources