1. Potentiometric Surface Map - September 2007 Sources of Nitrate and Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin, 2013. AMEC

2. Potentiometric Surface Map - September 2007 Springsheds Boundaries Delineated 2013 AMEC Study Boundary Sources of Nitrate and Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin, 2013. AMEC

3. Estimated Groundwater Recharge Rates Sources of Nitrate and Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin, 2013. AMEC

4. Aquifer Confining Layers in Alachua County

5. Aquafer Vulnerability and Stream-to-Sink Basins

6. Karst Landscapes http://www.nwfwmd.state.fl.us/water-resources/springs/learn-about-springs/

7. Flow pathways connecting surface sources to aquifer Unconfined Semi-Confined Confined “indirect” flowpath Surface runoff and subsurface pathway to aquifer via sinkholes “restricted” flowpath Mostly surface runoff and surficial aquifer with limited connection to aquifer “direct” flowpath Vertical leaching directly to aquifer

8. Nitrate Concentrations in upper Floridan Aquifer September 2012

9. Springsheds Study Area Land Use Sources of Nitrate and Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin, 2013. AMEC

10. Estimated Nitrate-Nitrogen Loading by Land Use

11. http://www.alachuacounty.us/Depts/epd/WaterResources/GroundwaterAndSprings/SFRSBWG%20Presentations/130926_Nitrate%20Study%20in%20the%20Santa%20Fe% 20Springs%20Restoration%20Focus%20Area_Katz.pdf

12. Sources of Nitrate and Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin, 2013. AMEC Groundwater Travel Times

13. (less than 100 years) Sources of Nitrate and Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin, 2013. AMEC

14. Mill Creek Sink Dye Trace Study http://www.alachuacounty.us/Depts/epd/WaterResources/GroundwaterAndSprings/Reports%20and%20Maps%20Documents/Mill%20Creek%20Sink%20Dye%20Trace %202005%20REPORTCmplt.pdf

15. Mill Creek & Lee Sink Dye Trace Study Dye released July 26, 11:34 Dye first detected in Hornsby spring August 8 (13 days later) Distance between Mill Creek sink and Hornsby Spring 6 miles Groundwater flow rate between Mill Creek Sink and Hornsby Springs 2,440 ft/day Lee Sink day trace travel rate 1,382 ft/day http://www.alachuacounty.us/Depts/epd/WaterResources/GroundwaterAndSprings/Reports%20and%20Maps%20Documents/Mill%20Creek%20Sink%20Dye%20Trace %202005%20REPORTCmplt.pdf

17. Cover-subsidence sinkholes -Cover-subsidence sinkholes tend to develop gradually where the covering sediments are permeable and contain sand. In areas where cover material is thicker or sediments contain more clay, cover-subsidence sinkholes are relatively uncommon, are smaller, and may go undetected for long periods. Cover-collapse sinkholes - Cover-collapse sinkholes may develop abruptly (over a period of hours). They occur where the covering sediments contain a significant amount of clay. Two Types of Sinkhole Formation US Geological Service

18. Stormwater Basins in Karst Landscapes - prone to sinkhole formation - Alternative - Dispersed Treatment Train: Provides treatment near source thereby reducing volume and contaminant loads in attenuation pond. Shallower pond depths lower hydraulic head pressure and allow for greater soil thickness between bottom of pond and underlying limestone. Increases treatment surface area for soil, plant, and microbial interaction to improve water quality. Distributes risk among multiple treatment cells each of which has lower potential for solution/sink formation.

19. Can We Achieve 0.35 mg/L Nitrate-Nitrogen? Loadings to Lower Santa Fe Springsheds Sources of Nitrate and Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin, 2013. AMEC

20. Back of Envelope Calculation 1: How much N Fertilizer can you lose per hectare and stay below nitrate standards? Loss of 30 kg/ha in one years worth of recharge (assume 12 in ~0.3 m 3 /m 2 )= 10 mg/l (Class I drinking water standard) Loss of 1 kg/ha in one years worth of recharge (assume 12 in ~0.3 m 3 /m 2 )= 0.35 mg/l (Class III springs nitrate standard)

21. Land useAssumed Average Leaching concentration Hectares of Native Vegetation per hectare of land use (assuming no denitrification) Hectares of Native Vegetation per hectare of land use (assuming 30% denitrification) Forage 1 0.85 mg/l1.4 ha0.7 ha Planted Pine 3 1.0 mg/l1.9 ha1 ha Residential 4 2.0 mg/l5 ha3 ha Citrus 2 7.5 mg/l20 ha14 ha Poultry 1 10 mg/l28 ha19 ha Row Crop 1 25 mg/l70 ha47 ha Dairy 1 42.5 mg/l120 ha84 ha For every hectare of intensive land use within a springshed how much native area (leaching at 0 mg/l) do you need to achieve 0.35 mg/l ? Back of Envelope Calculation 2: 1 Graetz et al, 2008; 2 Graham et al, 2000 3 Harper et al.,2007 4 Tucker et al, 2013 fertilizer, no septic tanks

22. Past and Projected Nitrate Loads Sources of Nitrate and Estimated Groundwater Travel Times to Springs of the Santa Fe River Basin, 2013. AMEC

23. Gronberg, J.M., and Spahr, N.E., 2012, County-level estimates of nitrogen and phosphorus from commercial fertilizer for the Conterminous United States, 1987–2006: U.S. Geological Survey Scientific Investigations Report 2012-5207, 20 p. Nitrogen Fertilizer Use in Alachua County 1987-2006