Coastal Watershed Assessment of Timucuan Ecological and Historic Preserve

COASTAL WATERSHED ASSESSMENT OF TIMUCUAN ECOLOGICAL AND HISTORIC PRESERVE: FOCUS ON WATER QUALITY AND LAND USE By SARAH M. ANDERSON A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING UNIVERSITY OF FLORIDA 2005 Copyright 2005 by Sarah M. Anderson This document is dedicated to my parents and sisters who have provided unwavering support and unconditional love throughout my life. iv ACKNOWLEDGMENTS I would like to acknowledge my committee chair, Dr. William Wise, for his support, guidance, and help in shaping my research objectives and goals. In addition, I would like to thank Dr. Andrew James and Dr. Joseph Delfino for serving on my committee and sharing their expertise. Special thanks go to Armin Feldman and Christine Katin who were instrumental in the completion of the National Park Service reports. Christine edited both reports and provided much constructive feedback. I would like to thank a number of individuals for their help and guidance in the preparation of Chapter 2 of this document. Special thanks go to Richard Bryant, Chief of Resources Stewardship for Timucuan Preserve, and Shauna Ray Allen, formerly the Natural Resource Program Manager for Timucuan Preserve, for answering numerous questions and providing valuable information during site visits. In addition, Richard Bryant critically reviewed a first draft of the chapter. Dana Morton of the City of Jacksonville Ambient Water Quality Section provided the water quality data specific to the preserve, fielded questions regarding the data collection and analysis, and allowed me to accompany him during his routine sampling. There are numerous other individuals requiring acknowledgement, specifically employees of the St. Johns River Water Management District, U.S. Geological Survey, and the Florida Department of Environmental Protection. The contributions of these individuals were greatly appreciated. v I would also like to thank the Nassau County Property Appraiser’s Office, specifically Tammy Stiles, for supplying the parcel data used for the land use analyses discussed in Chapter 3. Thanks to Dr. Bhramar Mukherjee for assistance with statistical analysis of the water quality data. I would also like to thank the National Park Service, Water Resources Division, for funding the project. In addition, I would like to thank CDM for providing financial support during my first year of graduate education. I cannot express the gratitude and appreciation which are reserved for my family and friends. They have provided constant encouragement and support throughout this experience. I would especially like to thank all the students in the Environmental Engineering Sciences and Soil and Water Science Departments, especially Shannon Curtis and Julie Padowski, for making the past few years entertaining and unique. Special thanks are also reserved for Jeff Smith who continues to inspire and challenge me each day. To my parents and sisters, I can never thank them enough. I greatly appreciate all of their encouragement and love. vi TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iv LIST OF TABLES............................................................................................................. ix LIST OF FIGURES .......................................................................................................... xii ABSTRACT................................................................................................................... xviii CHAPTER 1 INTRODUCTION ........................................................................................................1 Nutrients and Land Use ................................................................................................3 Site Description: Timucuan Ecological and Historic Preserve.....................................5 2 ASSESSMENT OF COASTAL WATER RESOURCES AND WATERSHED CONDITIONS AT TIMUCUAN ECOLOGICAL AND HISTORIC PRESERVE ..13 Executive Summary....................................................................................................13 Park Description .........................................................................................................22 Background..........................................................................................................22 Environmental setting ..................................................................................22 Land use .......................................................................................................27 Coastal management issues..........................................................................33 Hydrologic Information.......................................................................................43 St. Johns River..............................................................................................43 Nassau River ................................................................................................45 Sisters Creek (Intracoastal Waterway).........................................................46 Nassau Sound ...............................................................................................46 Freshwater ponds..........................................................................................49 Groundwater resources.................................................................................50 Water Resources Assessment .....................................................................................55 Water Quality ......................................................................................................55 Data sources .................................................................................................55 Water quality in TIMU and surrounding estuarine areas.............................57 Water Quality Impairments ...............................................................................108 Nearfield impairments in TIMU and surrounding estuarine areas.............109 Farfield impairments in TIMU and surrounding estuarine areas ...............114 vii Groundwater quality...................................................................................117 Conclusions and Recommendations.........................................................................121 Current Level of Knowledge .............................................................................121 Data management.......................................................................................121 St. Johns and Nassau Rivers.......................................................................124 Tidal creeks ................................................................................................124 Wells (groundwater)...................................................................................125 Spanish Pond (freshwater resources) .........................................................126 Atlantic coast..............................................................................................126 Identification of Data Gaps and Monitoring Recommendations.......................127 Data management.......................................................................................128 St. Johns and Nassau Rivers.......................................................................128 Tidal creeks ................................................................................................129 Wells (groundwater)...................................................................................131 Spanish Pond (freshwater resources) .........................................................132 Atlantic coast..............................................................................................133 3 INVESTIGATION OF WATER QUALITY CONDITIONS AND LAND USE IN NASSAU RIVER BASIN ........................................................................................134 Introduction...............................................................................................................134 Methods ....................................................................................................................142 Site Description .................................................................................................142 Water Quality Conditions..................................................................................142 Available water quality data.......................................................................142 Database structure and management ..........................................................145 Data considerations ....................................................................................146 Data analysis ..............................................................................................152 Land Use Analysis.............................................................................................153 Data sources ...............................................................................................153 Data analysis ..............................................................................................155 Results and Discussion .............................................................................................164 Water Quality Conditions..................................................................................164 Water quality characteristics ......................................................................164 Temporal trends..........................................................................................170 Spatial analysis...........................................................................................184 Relationships between water quality parameters .......................................187 Land Use Analysis.............................................................................................188 Pollution Load Screening Model (PLSM) .................................................188 Buffer zone approach .................................................................................194 Conclusions...............................................................................................................203 Water Quality Conditions..................................................................................203 Land Use Analysis.............................................................................................203 4 SYNTHESIS AND RECOMMENDATIONS .........................................................206 viii APPENDIX A LIST OF ACRONYMS ............................................................................................212 B DATA LAYER SOURCES......................................................................................214 C REGRESSION DIAGNOSTICS..............................................................................216 D CORRELATION ANALYSIS .................................................................................233 LIST OF REFERENCES.................................................................................................249 BIOGRAPHICAL SKETCH ...........................................................................................266 ix LIST OF TABLES Table page 2-1 Potential for impairment of Timucuan Ecological and Historic Preserve water resources...................................................................................................................19 2-2 Recommendations for Timucuan Ecological and Historic Preserve........................21 2-3 Land use distribution for Timucuan Ecological and Historic Preserve. ..................31 2-4 Descriptions of U.S. Fish and Wildlife National Inventory major systems and area of each system type located in Timucuan Ecological and Historic Preserve. ..33 2-5 Shoreline changes along the northeast Florida coast in the vicinity of the Fort George Inlet..............................................................................................................36 2-6 Dredging location and placement of dredged material for three sediment management alternatives considered in Fort George Inlet vicinity..........................37 2-7 Results from 2004 sampling of Spanish Pond. ........................................................51 2-8 Approximate correlation of hydrologic units and geologic formations with associated hydrologic properties. .............................................................................52 2-9 Water quality criteria used for assessment of Timucuan Ecological and Historic Preserve. ...................................................................................................................58 2-10 Total nitrogen and total phosphorus means (± standard deviation) at Timucuan Preserve Program sampling stations, February 1997 to April 2004. .......................67 2-11 Comparison of nutrient levels in selected Timucuan Ecological and Historic Preserve stations to South Carolina Estuarine Coastal Assessment Program..........68 2-12 Stations, date range, and parameters of interest with more than one record in modernized STORET sampled by the FDEP...........................................................76 2-13 Stations, date range, and parameters of interest within Timucuan Preserve study area from St. Johns River Water Management District database.............................78 2-14 Shellfish propagation or harvesting waters in Duval and Nassau Counties.............88 x 2-15 Metals of concern at stations sampled within study area surrounding Timucuan Ecological and Historic Preserve. ............................................................................95 2-16 Impaired waters within Timucuan Ecological and Historic Preserve study area based on Lower St. Johns River Basin verified list................................................111 2-17 Impaired waters within Timucuan Ecological and Historic Preserve study area based on Nassau/St. Marys Basin draft verified list...............................................113 2-18 Secondary drinking water standards utilized for assessment of Timucuan Ecological and Historic Preserve. ..........................................................................118 2-19 Potential for impairment of Timucuan Ecological and Historic Preserve water resources.................................................................................................................122 3-1 Land use in Nassau River Basin for 1970, 1990, and 2000. ..................................135 3-2 Data qualifier codes used for Timucuan Preserve Program data. ..........................146 3-3 Method detection and practical quantitation limits associated with Timucuan Preserve Program data............................................................................................147 3-4 Slope and intercept values for linear regressions of TP (mg/L) data for three substitution scenarios (n=42) at station TIM8........................................................149 3-5 Land use categories for spatial analysis. ................................................................156 3-6 Runoff coefficients for land use/soil combinations................................................160 3-7 Stormwater concentrations (mg/L) by land use. ....................................................161 3-8 Nutrient concentrations (mg/L) and Secchi depth measurements (m) as mean and range for eight Timucuan Preserve Program stations......................................167 3-9 Slope and intercept values for linear regressions of TP data for eight Timucuan Preserve Program stations ......................................................................................171 3-10 Slope and intercept values for linear regressions of TN data for eight Timucuan Preserve Program stations ......................................................................................171 3-11 Slope and intercept values for linear regressions of Secchi depth data for eight Timucuan Preserve Program stations.....................................................................172 3-12 Summary of significant relationships (p<0.10) between water quality parameters at Timucuan Preserve stations................................................................................188 3-13 Forecasted annual stormwater pollutant loads in metric tons (MT) for existing land use (2004) scenario.........................................................................................191 xi B-1 Contact information for retrieval of spatial data layers..........................................214 D-1 Pearson’s product moment-correlation coefficients and Kendall’s Tau between water quality and physical parameters for station TIM1........................................234 D-2 Pearson’s product moment-correlation coefficients and Kendall’s Tau between water quality and physical parameters for station TIM2........................................236 D-3 Pearson’s product moment-correlation coefficients and Kendall’s Tau between water quality and physical parameters for station TIM3........................................238 D-4 Pearson’s product moment-correlation coefficients and Kendall’s Tau between water quality and physical parameters for station TIM4........................................240 D-5 Pearson’s product moment-correlation coefficients and Kendall’s Tau between water quality and physical parameters for station TIM5........................................242 D-6 Pearson’s product moment-correlation coefficients and Kendall’s Tau between water quality and physical parameters for station TIM6........................................244 D-7 Pearson’s product moment-correlation coefficients and Kendall’s Tau between water quality and physical parameters for station TIM7........................................246 D-8 Pearson’s product moment-correlation coefficients and Kendall’s Tau between water quality and physical parameters for station TIM8........................................248 xii LIST OF FIGURES Figure page 1-1 Location of Timucuan Ecological and Historic Preserve in northeast Florida ..........6 1-2 Three salinity zones of Lower St. Johns River...........................................................8 1-3 Three salinity zones of Nassau River.........................................................................9 1-4 Process for assessment of coastal water resources and watershed conditions .........11 2-1 Location of Timucuan Ecological and Historic Preserve in northeast Florida ........22 2-2 Hydrologic unit codes (HUCs) in northeast Florida ................................................28 2-3 Jacksonville, Florida, area population, 1960-2000 ..................................................29 2-4 Land use within Timucuan Ecological and Historic Preserve .................................30 2-5 U.S. Fish and Wildlife Service National Wetland Inventory data for Timucuan Ecological and Historic Preserve .............................................................................32 2-6 Locations of proposed borrow sites for three sediment management alternatives in Fort George Inlet vicinity.....................................................................................38 2-7 Points of interest near Mile Point.............................................................................40 2-8 Landforms and hydrologic features of the southern portion of Timucuan Ecological and Historic Preserve .............................................................................47 2-9 Landforms and hydrologic features of the northern portion of Timucuan Ecological and Historic Preserve .............................................................................48 2-10 Locations of Timucuan Preserve Program stations (City of Jacksonville monitoring program) ................................................................................................66 2-11 Total nitrogen (mg/L) concentrations at selected stations, 1997-2004 ....................70 2-12 Total phosphorus concentrations (mg/L) at selected TIMU stations, 1997-2004....72 2-13 Total phosphorus concentrations (mg/L) at selected stations, 1997-2004 ...............73 xiii 2-14 Locations of FDEP stations within Timucuan Preserve study area .........................75 2-15 Locations of St. Johns River Water Management District stations within Timucuan Preserve study area..................................................................................77 2-16 Chlorophyll a measurements (µg/L) at station JAXSJR01, December 1999 – December 2003 ........................................................................................................79 2-17 Chlorophyll a measurements (µg/L) at station JAXSJR04, January 1999 – December 2003 ........................................................................................................79 2-18 Chlorophyll a measurements (µg/L) at station JAXSJR09, October 1999 – September 2003........................................................................................................80 2-19 Average monthly dissolved oxygen (±standard deviation) concentrations (mg/L) at Timucuan Preserve Program stations, February 1997-April 2004.......................82 2-20 Surface dissolved oxygen (mg/L) measurements at station TIM8, 1997-2004 .......82 2-21 Surface dissolved oxygen (mg/L) measurements at station TIM12, 1997-2004 .....83 2-22 Location of station 3537...........................................................................................83 2-23 Surface dissolved oxygen (mg/L) measurements at station 3537, October 1998- March 2003 ..............................................................................................................84 2-24 Florida Healthy Beaches Program stations located within Timucuan Ecological and Historic Preserve study area ..............................................................................90 2-25 Number of samples and enterococcus poor ratings for Florida Healthy Beaches stations (n =7) located within Timucuan Ecological and Historic Preserve study area, August 2000 to January 2004 ..........................................................................90 2-26 Locations of stations 20030653, SC1, and SC3 near Timucuan Ecological and Historic Preserve ......................................................................................................91 2-27 Interpretation of enrichment factor using lead/aluminum relationship..................101 2-28 Environmental Monitoring and Assessment Program (EMAP) and National Coastal Assessment (NCA) sampling stations, 1993-1995....................................106 2-29 Verified (or draft verified list) impaired waterbodies located within Timucuan Preserve study area.................................................................................................110 2-30 Planning units in the Lower St. Johns River Basin ................................................116 3-1 Drainage features of the Nassau River Basin.........................................................134 xiv 3-2 Location of Timucuan Ecological and Historic Preserve in relation to surface water basins ............................................................................................................136 3-3 Locations of selected Timucuan Preserve Program stations and corresponding hydrologic features.................................................................................................137 3-4 Three salinity zones of Nassau River.....................................................................143 3-5 Time series plots using different substitution values for measurements below detection for TP at station TIM8, 1997-2004.........................................................148 3-6 Procedure used for processing of Timucuan Preserve Program data.....................150 3-7 SJRWMD 1995 land use and parcels developed between 1997 and 2004 for Lofton Creek watershed .........................................................................................154 3-8 Diagram of Pollution Load Screening Model framework......................................156 3-9 Annual precipitation at Jacksonville International Airport, 1997-2004.................159 3-10 Box and whisker plots for TP (mg/L) for eight Timucuan Preserve Program stations, 1997-2004. ...............................................................................................165 3-11 Box and whisker plots for TN (mg/L) for eight Timucuan Preserve Program stations, 1997-2004 ................................................................................................165 3-12 Box and whisker plots for TKN (mg/L) for eight Timucuan Preserve Program stations, 1997-2004. ...............................................................................................166 3-13 Box and whisker plots for Secchi depth (m) for eight Timucuan Preserve Program stations, 1997-2004..................................................................................166 3-14 Time series plots of TP (mg/L) for selected Timucuan Preserve Program stations, 1997-2004 ................................................................................................173 3-15 Time series plots of TN (mg/L) for selected Timucuan Preserve Program stations, 1997-2004 ................................................................................................175 3-16 Time series plots of Secchi depth (m) for selected Timucuan Preserve Program stations, 1997-2004 ................................................................................................177 3-17 Time series plot of TP (mg/L) at U.S. Highway 17 in the Nassau River, 1997- 2004 (n=82)............................................................................................................178 3-18 Time series plot of TN (mg/L) at U.S. Highway 17 in the Nassau River, 1997- 2004 (n=67)............................................................................................................179 3-19 Time series plot of TP (mg/L) at U.S. Highway 17 in the Nassau River, 1976- 2004 (n=158)..........................................................................................................179 xv 3-20 Time series plot of TN (mg/L) at U.S. Highway 17 in the Nassau River, 1976- 2004 (n=128)..........................................................................................................180 3-21 Percent of nitrate and ammonia measurements below detection at eight Timucuan Program sampling stations, 1997-2004.................................................181 3-22 Comparisons of median TP concentrations (mg/L) from Timucuan Preserve Program to USGS study (Coffin et al., 1992) ........................................................182 3-23 Comparisons of median TN concentrations (mg/L) from Timucuan Preserve Program to USGS study (Coffin et al., 1992) ........................................................183 3-24 Comparisons of median Secchi depths (m) from Timucuan Preserve Program to USGS study (Coffin et al., 1992) ...........................................................................183 3-25 Mean TP (mg/L) concentrations along Nassau River for eight Timucuan Preserve stations, 1997-2004..................................................................................184 3-26 Mean TN (mg/L) concentrations along Nassau River for eight Timucuan Preserve Program stations, 1997-2004...................................................................185 3-27 Mean TKN (mg-N/L) levels along Nassau River for eight Timucuan Preserve stations, 1997-2004 ................................................................................................185 3-28 Mean Secchi depth (m) along Nassau River for eight Timucuan Program stations, 1997-2004 ................................................................................................185 3-29 Mean salinity measurements (ppt) along Nassau River for eight Timucuan Program stations, 1997-2004..................................................................................186 3-30 Mean specific conductance (µS/cm) along Nassau River for eight Timucuan Program stations, 1997-2004..................................................................................186 3-31 Land use for Lofton Creek watershed derived from parcel data............................189 3-32 Parcels with stormwater treatment efficiencies applied.........................................190 3-33 Parcels converted to urban land use in the future land use scenario ......................192 3-34 Parcels built on between 1997 and 2004 in the southern portion of the Lofton Creek watershed .....................................................................................................194 3-35 Land use distribution for 500-m (1,640-ft) buffer around Lofton Creek ...............195 3-36 Land use within 500-m (1,640-ft) buffer around Lofton Creek.............................196 3-37 Number of parcels converted to low density and single family residential land use in 500-m (1,640-ft) buffer zone, 1997-2004....................................................197 xvi 3-38 Relationships between buffer land use parameters and annual maximum (▲), median (‹), and minimum (■) TP concentrations (mg/L)....................................199 3-39 Relationships between buffer land use parameters and annual maximum (▲), median (‹), and minimum (■) TN concentrations (mg/L) ...................................200 3-40 Aerial verification of land use within 100- and 500-m (328- and 1,640-ft) buffers of the southern portion of Lofton Creek ....................................................202 C-1 Regression diagnostics for linear regression of Secchi depth (m) at station TIM1.216 C-2 Regression diagnostics for linear regression of Secchi depth (m) at station TIM2.217 C-3 Regression diagnostics for linear regression of Secchi depth (m) at station TIM3.218 C-4 Regression diagnostics for linear regression of TN (mg/L) at station TIM1 .........219 C-5 Regression diagnostics for linear regression of TN (mg/L) at station TIM2 .........220 C-6 Regression diagnostics for linear regression of TN (mg/L) at station TIM3 .........221 C-7 Regression diagnostics for linear regression of TN (mg/L) at station TIM4 .........222 C-8 Regression diagnostics for linear regression of TN (mg/L) at U.S. Highway 17 in the Nassau River (1997-2004) ...........................................................................223 C-9 Regression diagnostics for linear regression of TN (mg/L) at U.S. Highway 17 in the Nassau River (1981-2004) ...........................................................................224 C-10 Regression diagnostics for linear regression of TP (mg/L) at station TIM3..........225 C-11 Regression diagnostics for linear regression of TP (mg/L) at station TIM4..........226 C-12 Regression diagnostics for linear regression of TP (mg/L) at station TIM5..........227 C-13 Regression diagnostics for linear regression of TP (mg/L) at station TIM6..........228 C-14 Regression diagnostics for linear regression of TP (mg/L) at station TIM7..........229 C-15 Regression diagnostics for linear regression of TP (mg/L) at station TIM8..........230 C-16 Regression diagnostics for linear regression of TP (mg/L) at U.S. Highway 17 in the Nassau River (1997-2004)................................................................................231 C-17 Regression diagnostics for linear regression of TP (mg/L) at U.S. Highway 17 in the Nassau River (1976-2004)................................................................................232 D-1 Standard pair-wise correlation matrix for water quality and physical variables for station TIM1 .....................................................................................................233 xvii D-2 Standard pair-wise correlation matrix for water quality and physical variables for station TIM2 .....................................................................................................235 D-3 Standard pair-wise correlation matrix for water quality and physical variables for station TIM3 .....................................................................................................237 D-4 Standard pair-wise correlation matrix for water quality and physical variables for station TIM4 .....................................................................................................239 D-5 Standard pair-wise correlation matrix for water quality and physical variables for station TIM5 .....................................................................................................241 D-6 Standard pair-wise correlation matrix for water quality and physical variables for station TIM6 .....................................................................................................243 D-7 Standard pair-wise correlation matrix for water quality and physical variables for station TIM7 .....................................................................................................245 D-8 Standard pair-wise correlation matrix for water quality and physical variables for station TIM8 .....................................................................................................247 xviii Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Engineering COASTAL WATERSHED ASSESSMENT OF TIMUCUAN ECOLOGICAL AND HISTORIC PRESERVE: FOCUS ON WATER QUALITY AND LAND USE By Sarah M. Anderson December 2005 Chair: William R. Wise Major Department: Environmental Engineering Sciences Non-point source pollution generated from anthropogenic activities is a significant source of nutrients to receiving waters. Estuaries are particularly vulnerable due to high rates of urban and residential growth near coastal waters. In recognition of the varied threats to coastal resources, the National Park Service plans to complete scientific assessments of 52 ocean and Great Lake parks. The report concerning Timucuan Ecological and Historic Preserve (TIMU), located in northeast Florida, was completed in 2005. This research includes the water resources portion of the assessment and supplementary analysis of water quality data and land use conditions in the Nassau River Basin. Water quality data from the City of Jacksonville’s Timucuan Preserve Program were reviewed for spatial and temporal trends (1997 to 2004). As part of this program, eight stations in the main stem of Nassau River and its contributing tidal creeks are sampled bimonthly. Spatially, nutrient concentrations typically decreased with xix increasing salinity, most likely due to dilution with ocean water. Temporally, increasing total phosphorus levels were observed at six of the eight stations and increasing total nitrogen levels at four stations. Also, decreasing trends in Secchi depth, a measure of water clarity, were observed at three stations. The frequency of nitrate values above the detection limit also increased over the same period. Despite the observed trends, median values of these parameters were similar to those reported in a characterization study of the basin conducted from 1982 to 1989. The potential water quality effects of future land use changes in the Lofton Creek watershed were estimated using a stormwater load screening model developed by the St. Johns River Water Management District. When approximately 10 percent of the watershed was converted to residential land uses, the model forecasted increases of approximately 8.5 and 0.8 metric tons in the annual total nitrogen and phosphorus loads. Inspection of aerial photographs provided an initial evaluation of land use in varying size buffer zones around Lofton Creek. Most of the land within 100 m (328 ft) of the creek consists of forests and wetlands; however, significant residential development and part of a golf course are located within 500 m (1,064 ft) of the creek. Nutrient levels should continue to be closely monitored, given the increasing trends observed at multiple stations and anticipated residential development in the area. Currently, the environmental effects of urban land uses may be mitigated by the tidal flushing of the estuarine system. In this study, integration of recent monitoring data and land use analyses provided valuable information to direct future monitoring, planning, and land acquisition efforts. 1 CHAPTER 1 INTRODUCTION Non-point source pollution from urban and agricultural activities is a substantial source of phosphorus (P) and nitrogen (N) to waterbodies in the United States (Carpenter et al., 1998). Non-point sources of pollution include septic tank leachate, groundwater intrusion, atmospheric deposition, runoff from roadways, and agricultural stormwater runoff from row crops, pasture, and forest lands (Maher, 1997). Point sources introduce water at identifiable locations such as wastewater treatment plants (domestic and industrial) and agricultural canals. Historically, point sources have been effectively managed due to the ease of monitoring and implementation of control measures (Carpenter et al., 1998). Delivery of excess nutrients to coastal waters can lead to numerous problems such as widespread fish kills, harmful algal blooms, loss of habitat and diversity, and increased frequency and duration of hypoxic or anoxic events (Carpenter, 1998; National Research Council [NRC], 2000). Eutrophication has been defined as an increase in the rate that organic matter is supplied to an aquatic system (Nixon, 1995). Eutrophication is considered a natural process, whereas, the term “nutrient over-enrichment” has been used to designate excessive nutrient loading from anthropogenic activities that adversely affects waterbodies (United States Environmental Protection Agency [USEPA], 2001). Nutrient over-enrichment is a widespread problem in estuaries and coastal waters around the world. In an assessment of the eutrophic conditions in United States estuaries, Bricker et al. (1999) concluded that about 60 percent of the 138 estuaries studied 2 exhibited moderate to serious eutrophic conditions. In the 2004 Integrated Water Quality Assessment for Florida (Florida Department of Environmental Protection [FDEP], 2004c), nutrients (based on chlorophyll data) were listed as one of the parameters causing estuarine impairment. Examples of eutrophic ecosytems are the Baltic Sea, Caspian Sea, Chesapeake Bay (Maryland and Virginia), and the Neuse River Estuary (North Carolina). A number of factors influence the susceptibility of estuaries to nutrient loading (NRC, 2000; USEPA, 2001). These considerations include water residence time or flushing rate, vertical mixing or degree of stratification, algal biomass, ratio of nutrient load per unit area of estuary, depth distribution, and wave exposure (USEPA, 2001). This list is expected to expand as scientists, engineers, and resource managers learn more about nutrient cycling in specific estuaries. Management of coastal resources is complicated by the absence of numeric criteria for comparison of nutrient water quality data. Florida’s nutrient criterion is narrative, stating that nutrient concentrations shall not be altered as to cause as imbalance in natural populations of aquatic flora or fauna (Subsection 62-303.350, Florida Administrative Code [FAC]). Estuarine segments are placed on the planning list of impaired waters if the mean annual chlorophyll a concentration is greater than 11 µg/L or if mean annual values have increased by more than 50 percent over historical values for at least two consecutive years (Subsection 62-303.353, FAC). In addition, other indicators of nutrient enrichment, such as algal blooms, decreases in extent and/or density of submerged aquatic vegetation, and excessive macrophyte growth, are also considered when determining if a waterbody is impaired. The numeric nutrient criteria established for 3 coastal waters are expected to be variable and specific to each waterbody, unlike freshwater bodies, which are more likely to be grouped into classes (USEPA, 2001). The natural and anthropogenic factors that influence water quality operate at a variety of spatial and temporal scales. Natural factors include precipitation, surficial geology, topography, vegetation, and watershed and flow characteristics, while anthropogenic effects are associated with land use/land cover (Soranno et al., 1996; Baker, 2003). Researchers have developed relationships between landscape characteristics and water quality as non-point source pollution has become of increasing importance in watershed management. Nutrients and Land Use Numerous studies have discussed the relationships between nutrients and land use (Beaulac and Reckhow, 1982; Osborne and Wiley, 1988; Sorrano et al., 1996; Johnson et al., 1997; Tong and Chen, 2002; Holland et al., 2004). In South Carolina tidal creeks, total phosphorus (TP) was positively correlated with urban development, population density, and percent imperviousness (Van Dolah et al., 2004a). Urban development was the major factor controlling elevated levels of soluble reactive P during low flow periods in a Midwestern watershed (Osborne and Wiley, 1988). Nitrate concentrations were linked to agricultural fertilizer applications in late winter and early spring and urban runoff in the summer and autumn (Osborne and Wiley, 1988). Urban land use was the best predictive measure of water quality variability in a study of three watersheds in Ontario, Canada (Sliva and Williams, 2001). The effects of land use on additional water quality parameters, such as Secchi depth, have proven more difficult to ascertain (Bruhn and Soranno, 2005). Much of this work has focused on freshwater streams, studies 4 addressing the impacts of urban development on tidal rivers and estuarine waters are not as prevalent (Van Dolah et al., 2004a). A number of comparative studies have examined whether land use in the riparian zone or a portion of the watershed is more closely related to water quality than the entire catchment (Griffith, 2002). These studies have produced inconsistent results. Sliva and Williams (2001) found that water quality was slightly better correlated with landscape variables at the catchment level compared to a 100-m (328-ft) buffer. Hunsaker and Levine (1995) reported that land use in the entire watershed explained more variability in water quality parameters than 200- and 400-m (656- and 1312-ft) buffer strips. In contrast, Johnson et al. (1997) reported that buffer characteristics explained slightly more of the seasonal variation for several constituents than the entire catchment. However, the two measures had similar predictive ability, possibly because land use in the buffer zones was representative of the entire watershed (Johnson et al., 1997). Soranno et al. (1996) concluded that the area contributing most strongly to nutrient loading was much less the entire watershed and strongly related to precipitation. As much as one half of the study watershed did not contribute significantly to the annual P loading (Soranno et al., 1996), indicating that inclusion of the entire watershed in loading calculations may overestimate results. The buffer width required to accurately characterize land use effects is an additional consideration. Several studies have utilized 100-m buffers to incorporate land use effects on receiving waters (Johnson et al., 1997; Sliva and Williams, 2001; Brown and Vivas, 2005). Osborne and Wiley (1988) found that the effects of proposed development on nutrient concentrations were greatly reduced at distances of 305 m (1000 5 ft) from the river channel. Conversely, some studies have demonstrated that remote land uses in a watershed, which would favor the entire catchment approach, can significantly impact water quality. Houlahan and Findlay (2004) found that land use, particularly forest cover, was correlated with N and P concentrations over 2 km (1.2 miles) from the edge of wetlands. The size of buffers required to adequately characterize land use may vary geographically. Due to the relatively flat terrain of Florida, a 100-m buffer accurately characterized human disturbance to the landscape surrounding waterbodies (Brown and Vivas, 2005). For a future development scenario along an urban-rural gradient, Wear et al. (1998) projected that water quality would be disproportionately influenced by the most remote portion of the landscape and that at the edge of urban expansion. In both of these areas, the greatest amount of total land cover change and reduction in forest cover occurred (Wear et al., 1998). Relationships between land use and water quality are often region- or site-specific (Baker, 2003), emphasizing the need for additional research into the mechanisms responsible for the observed water quality changes to determine if broadscale application is possible. Site Description: Timucuan Ecological and Historic Preserve Timucuan Ecological and Historic Preserve (TIMU) located in northeast Florida, covers approximately 18,600 hectares (46,000 acres) and contains the seaward confluences of the Nassau and St. Johns Rivers (Figure 1-1). The estuarine system is characterized by extensive salt marsh and coastal hammock habitat in addition to brackish and open waters. The economical, social, and environmental benefits of the system are immeasurable. Several rare and vulnerable natural communities: coastal strand, maritime hammock, scrub, and shell mound, are located within TIMU. Species of 6 interest in the area include the Florida manatee (Trichechus manatus latirostrus), diamondback terrapin (Malaclemys terrapin Tequesta), loggerhead sea turtle (Caretta caretta), and wood stork (Mycteria americana). Figure 1-1. Location of Timucuan Ecological and Historic Preserve in northeast Florida. (Sources: Park Boundary – National Park Serve [NPS], 1999; State – FDEP, 1997; Georgia shoreline – Federal Emergency Management Agency [FEMA], 1999) Water resources and wetlands comprise approximately 75 percent of TIMU’s area (NPS, 1996). TIMU occupies a region of the Atlantic Coast known as the Sea Islands. Sea Islands are barrier islands separated from the mainland by numerous tidal creeks. Sedimentation occurs behind the barrier islands that provide protection by absorbing much of the wave and tidal energy. Salt marshes located in the sedimentation areas have 7 been recognized for their high primary productivity and importance as a food supply for consumers (Durako et al., 1988; NPS, 1996). These consumers are often commercially important species, such as finfish and shellfish. The significance of these systems from ecological and economic standpoints has not been reflected in the amount of study or integration of available information. The two predominant drainage features located within the TIMU boundary are the Nassau and St. Johns Rivers. Additional hydrologic features in TIMU are numerous meandering tidal creeks, Sister’s Creek/Intracoastal Waterway (ICWW), the Ft. George River, and freshwater resources. Spanish Pond is the largest freshwater resource under NPS ownership within TIMU. The St. Johns River (SJR) is the longest river in Florida and one of the longest blackwater rivers in the southeastern United States (Hendrickson et al., 2003). The lower St. Johns River (LSJR) Estuary is the northern 163 km (101 mi) of the river that extends from the mouth of the Oklawaha River in Putnam County to the inlet at the Atlantic Ocean. The LSJR is separated into three ecological zones based on salinity (Figure 1-2). The freshwater tidal lacustrine zone in the southern region extends from the city Palatka north to the city of Orange Park with a mean salinity of 0.5 parts per thousand (ppt). The riverbed then broadens and becomes shallow and slow-moving through the predominantly oligohaline lacustrine zone extending from Orange Park north to the Fuller Warren Bridge (I-95) in Jacksonville with a mean salinity of 2.9 ppt. The northern zone from the Fuller Warren Bridge to the river mouth is described as meso-polyhaline riverine with an average salinity of 14.5 ppt (Maher, 1997; Hendrickson and Konwinski, 1998). The LSJR has been recognized as an impaired waterbody due to point and non- 8 point pollution sources (Hendrickson and Konwinski, 1998; FDEP, 2004b), which include residential, commercial, and industrial development; agricultural activities; and domestic wastewater and industrial discharges. Figure 1-2. Three salinity zones of Lower St. Johns River. (Sources: Basin – FDEP, 1997; Salinity zones – SJRWMD, 2005) The Nassau River drains an area of approximately 1,110 km2 (430 miles2 ) of land consisting predominantly of wetlands, salt marshes, and forests (Coffin et al., 1992). The Nassau River Estuary has been recognized for its relatively pristine condition compared to other estuarine systems on the east coast of the United States (Coffin et al., 1992). Similar to the LSJR, three salinity zones can be distinguished in the Nassau River (Figure 1-3). The western portion of the basin is predominantly freshwater, including Alligator, 9 Mills, and Thomas Creeks. The transitional zone from predominantly freshwater to saltwater extends from the confluence of Thomas Creek and Nassau River to a point about 3.2 km (two miles) downstream of U.S. Highway 17. The predominantly saline region extends from this point to Nassau Sound (Coffin et al., 1992). Figure 1-3. Three salinity zones of Nassau River. Red lines indicate division between predominantly freshwater, transition, and predominantly saltwater zones. (Sources: Park Boundary – NPS, 1999; County – FDEP, 1997; Roads – Florida Department of Transportation [FDOT], 2001) In freshwater systems, phytoplankton growth is considered to be P-limited, while N is the limiting macronutrient in marine and estuarine waters (Banks, 1997). The N limitation of marine waters has been attributed to the sulfate content of sea salts (Blomqvist et al., 2005). P is more available in anoxic marine environments because sulfides sequester iron, limiting the precipitation of phosphate (Blomqvist et al., 2005). The marine reaches of LSJR and Nassau River are considered to be primarily Nlimited (Banks, 1997; J. Hendrickson, personal communication, 15 June 2005). 10 However, DeMort and Bowman (1985) previously concluded that N was not the limiting nutrient in the LSJR due high N inputs from the surrounding swamps and wastewater discharges. These conflicting results may arise from the calculation of N to P (N:P) ratios, which do not reflect that much of the N in blackwater streams is present in refractory compounds and therefore, unavailable to phytoplankton (J. Hendrickson, personal communication, 15 June 2005). Management strategies cannot focus solely on N or P control. Although primary production in salt marshes tends to be N-limited, other organisms, such as bacteria, have demonstrated P limitation (Sundareshwar et al., 2003). In addition, the sensitivity of estuarine response to nutrient inputs can vary along a salinity gradient, with phosphorus inputs becoming more important as salinity decreases (Doering et al., 1995). Human development stresses in coastal zones have increased tremendously in recent years, particularly in Florida. In an overview of the status of the southeastern Unites States estuaries, Florida’s high population density and growth rate were considered one of the “most pressing environmental problems” facing the region (Dame et al., 2000, p. 793). In the Southeast, urban area is anticipated to increase from approximately 8 million hectares (20 million acres) in 1992 to 22 million hectares (55 million acres) in 2020 and 33 million hectares (81 million acres) in 2040 (Wear, 2002). In recognition of the increasing pressures and threats to the nation’s coastal resources, the NPS initiated scientific assessments of coastal parks, including TIMU. These reports, termed Coastal Watershed/Water Condition Reports, are the first phase in a two-phase process. They will be used to direct future efforts to further clarify known resource issues, identify supplementary resource stressors, and develop restoration and 11 cooperative management plans (NPS, 2005). Plans are underway to complete 52 reports for ocean and Great Lakes parks. The reports determine the status of each park’s resources, including water quality, habitat condition, invasive species, and additional issues, through review and synthesis of multiple information types (Figure 1-4). These sources include land use patterns and trends, water quality data, biological inventories, resource utilization issues, and impaired waters lists. This information was used to assess the condition of the park’s water resources, to identify knowledge gaps, and provide recommendations for further study. Each report contains a threat matrix which summarizes the potential for impairment of water quality indicators (water quality, habitat, coastal management issues, etc.). These charts will facilitate comparison between geographic units and parks. In addition, these tables will be used to prioritize future monitoring and management efforts. Figure 1-4. Process for assessment of coastal water resources and watershed conditions. (Adapted from NPS, 2005) Chapter 2 of this document contains excerpts of the portions of the watershed condition report focusing on water quality and coastal utilization issues for TIMU. Chapter 3 addresses the relationships between land use and water quality in the Nassau Land use patterns & trends Describe coastal water resources Determine state of knowledge Identify information gaps Draw conclusion regarding condition Identify resource threats Recommend further studies Information Types Water quality data & assessments Impaired waters lists Invasive species issues Resource utilization issues Goals Biological inventories & studies 12 River Basin. Chapter 4 discusses the results of the preceding chapters and implications for future monitoring and management efforts. 13 CHAPTER 2 ASSESSMENT OF COASTAL WATER RESOURCES AND WATERSHED CONDITIONS AT TIMUCUAN ECOLOGICAL AND HISTORIC PRESERVE Executive Summary Timucuan Ecological and Historic Preserve (TIMU) encompasses 18,600 hectares (46,000 acres) of salt marsh and coastal hammock habitat in addition to marine and brackish open waters. TIMU contains the seaward confluence of the Nassau and St. Johns Rivers (SJR). It is located along the northeastern coast of Florida (Duval County) entirely within the city limits of Jacksonville. TIMU includes several rare and vulnerable natural communities: coastal strand, maritime hammock, scrub, and shell mound. National Park Service (NPS) facilities within TIMU include Fort Caroline (FOCA) visitor center and maintenance area, the Theodore Roosevelt area with park headquarters, the Kingsley Plantation, the Ribault Column, and the newly-acquired historic Broward house. Other state and city parks in the area are Big and Little Talbot Island State Parks, Fort George Island Cultural State Park, Little Jetties Park, Huguenot Memorial Park, and the Sisters Creek Park and boat ramp. Water resources are an integral part of TIMU because approximately 75 percent of the area included within its boundaries is wetlands and open water. These resources include numerous tidal creeks, portions of the Nassau and SJR Rivers, Sisters Creek/Intracoastal Waterway (ICWW), Fort George River, and freshwater resources (Spanish Pond). TIMU’s estuarine setting serves as a vital ecological link between freshwater habitats and the ocean. 14 The waters of TIMU are impacted by land use in the surrounding watersheds. Examples of water quality issues applicable to TIMU include non-point source pollution from urban and agricultural areas, elevated metal concentrations in the sediments of the SJR, impacts of several Superfund sites and landfills, and water pollution from malfunctioning septic systems within and adjacent to TIMU. Available water quality information was utilized to determine the current condition and possible impairments of TIMU’s water resources, and to identify any information gaps that limit determination of whether or not TIMU’s waters are degraded or impaired. Generally, TIMU’s water quality is considered good compared to other Florida surface waters. Tidal flushing is considered to be an important contributing factor because upstream areas of the Nassau and St. Johns River are degraded. However, recent continuous monitoring data collected in the Fort George River indicates that some of the tidal creeks are not well flushed (DiDonato et al., 2005). Residence times were on the order of months, indicating that pollution to these areas could have prolonged effects. In addition, there is a lack of descriptive information detailing the hydrodynamics and currents of the system. Circulation of water within the tidal creeks east of Blount Island are considered especially complex. The Baseline Water Quality Data and Inventory Report (NPS, 2002) retrieved all water quality data entered into the U.S. Environmental Protection Agency (USEPA) STOrage and RETrieval (STORET) database for TIMU and the surrounding area (lands and waters within three miles upstream and one mile downstream) through 1998. The search yielded 493,316 observations for 532 separate parameters collected by various agencies. About 81 percent (400,249) of the observations were entered by the NPS from 15 data collected between 1972 and 1998. Of these observations, 97 percent were recorded at two stations (TIMU 0178 – Cedar Point Creek and TIMU 0213 – Clapboard Creek) within TIMU’s boundary. Forty-two stations within the study area did not contain any data and many of the stations represented one-time or intensive single-year sampling efforts. For this assessment, data were downloaded from the USEPA modernized STORET database, which includes all measurements after 1999, and a limited amount of earlier data that have been transferred from Legacy STORET. These data were contributed by the City of Jacksonville (COJ), the Florida Department of Environmental Protection (FDEP), Division of Environmental Health (Bureau of Water), Florida Fish and Wildlife Conservation Commission (FWCC) Marine Research Institute, NPS, and Florida LAKEWATCH. Additional sources of data were the TIMU Preserve Program (conducted by the City of Jacksonville), the St. Johns River Water Management District (SJRWMD), and the U.S. Geological Survey (USGS) National Water Information System (NWIS) database. Water quality impairments for the Lower St. Johns River Basin (LSJRB) and the Nassau/St. Marys Basin provide a starting point for determination of water quality conditions in TIMU. According to the verified list for the LSJRB, there are eight impaired segments in the water basins within the study area established around TIMU. Three of the segments are portions of the SJR including the mouth, the ICWW, and Dames Point. The three segments are all impaired due to iron, copper, and nickel with an additional listing for lead in the ICWW segment. The other segments, with the exception of the Atlantic Coast entry, are urban creeks that are listed as impaired due to dissolved 16 oxygen (DO) levels and fecal coliforms. There are 18 segments on the draft list of impaired waters in the Nassau/St. Marys Basin within the study area. The impaired parameters are DO, coliforms, iron, chlorophyll, mercury, and biology. Seven of the listings are for coliforms, resulting from downgrades in shellfish harvesting classifications. Much of the recent water quality information comes from the monitoring efforts of the COJ Ambient Water Quality Section, which samples twelve stations within and adjacent to TIMU. These sites are sampled on a bimonthly basis for numerous parameters such as nutrients (various forms of nitrogen [N] and phosphorus [P]) and DO. The nutrient levels at these stations were generally consistent with the typical values for Florida estuarine and stream stations as presented in Friedemann and Hand (1989). However, the total phosphorus (TP) levels at some of the stations exceeded the typical value >50 percent of the time. These stations should continue to be monitored as residential development pressure will likely increase in the future, which may impact P levels. DO measurements recorded at the COJ’s monitoring stations displayed seasonal cycling consisting of summer minima and winter maxima. Continuous monitoring has been conducted at several locations, Clapboard Creek and the Fort George River, to obtain hydrologic and water quality information. At one of these locations (in the Fort George River), measurements were recorded below 4.0 and 5.0 mg/L, which are the respective saltwater and freshwater state criteria. These instances may not be a cause for alarm, as short hypoxic events often occur during the summer in tidal creeks in this region (DiDonato et al., 2005). Overall, hypoxic events were rare, occurring during 6 17 percent of the deployment period, and short, none of the events lasted longer than 12 hours (DiDonato et al., 2005). Although most of the sediments within TIMU have showed little to no metal or organic contamination, some areas of contamination have been identified. The sediments of Spanish Pond were categorized as “moderately contaminated” with lead and zinc, probably due to stormwater road runoff (Morton and Marchman, as cited in NPS, 1996). Samples from Chicopit Bay exhibited elevated concentrations of arsenic, chromium, lead, and zinc; organic contaminants were detected in the SJR. Multiple years of high levels of selenium and butyltin compounds have also been documented in Chicopit Bay (O’Connor and Beliaeff, 1996). Additional data regarding contaminants, such as hydrocarbons, organic pollutants, pesticides, and metals, are available from the Environmental Monitoring and Assessment Program (EMAP). Stations in the South Amelia River and Nassau Sound did not demonstrate any evidence of water or sediment quality degradation; however, a station in the SJR displayed elevated levels of total polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT). The site was classified as degraded based on the mean infaunal diversity and abundance as well as the mean demersal richness, diversity, and abundance. In addition to water quality concerns, there are several other coastal management issues that should be mentioned. These matters include the possible closure of the Fort George inlet, which would affect the water quality of TIMU’s salt marshes. A larger portion (or all) of the water supplied to the marshes would originate from Nassau Sound and the SJR, which is most likely of lower quality than that from the Atlantic Ocean. Gosselin et al. (2000) investigated the impacts of three proposed alternatives on the wave 18 climate, tidal circulation, and potential sediment transport near the Fort George inlet to prevent this closure. The U.S. Army Corps of Engineers (USACOE) is investigating options to limit the navigational risks associated with the dangerous cross-currents at Mile Point. In addition to the dangerous currents, homeowners on the north bank of the SJR at Mile Point have experienced severe erosion of their property. The erosion of South Amelia Island led to the construction of a 460-m (1500-ft) terminal groin and a 90- m (300-ft) detached rock breakwater. Sea level rise may significantly affect coastal marshes. Predicting shoreline retreat and land loss rates has direct impacts on coastal zone management and biological resources. Altere