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

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, AMEC

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

Aquifer Confining Layers in Alachua County

Aquafer Vulnerability and Stream-to-Sink Basins

Karst Landscapes

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

Nitrate Concentrations in upper Floridan Aquifer September 2012

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

Estimated Nitrate-Nitrogen Loading by Land Use

20Springs%20Restoration%20Focus%20Area_Katz.pdf

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

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

Mill Creek Sink Dye Trace Study %202005%20REPORTCmplt.pdf

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 %202005%20REPORTCmplt.pdf

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

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.

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, AMEC

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)

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 mg/l1.4 ha0.7 ha Planted Pine mg/l1.9 ha1 ha Residential mg/l5 ha3 ha Citrus mg/l20 ha14 ha Poultry 1 10 mg/l28 ha19 ha Row Crop 1 25 mg/l70 ha47 ha Dairy 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, Harper et al., Tucker et al, 2013 fertilizer, no septic tanks

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

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 , 20 p. Nitrogen Fertilizer Use in Alachua County