Evaluation of Impairment in Silver Springs. Robert A. Mattson, CEP, CSE Environmental Scientist V St. Johns River Water Management District

Transcription

1 Evaluation of Impairment in Silver Springs Robert A. Mattson, CEP, CSE Environmental Scientist V St. Johns River Water Management District

2 Values of Silver Springs/River Fish and wildlife habitat Baseflow to lower Ocklawaha River Original Florida tourist attraction Centerpiece of an attraction and a state park High recreational value Generates economic activity for local economies

3 Silver Springs Springshed Source: Phelps USGS Scientific Investigations Report

4 Silver Springs Springshed Source: Phelps USGS Scientific Investigations Report

5 Sources of Water and Potential Contamination in Silver Springs

6 Groundwater Source Studies Silver Springs basin - nitrate in ground water primarily indicates inorganic (fertilizer) source, with some organic contribution (wastewater, manure). Some emerging contaminants were identified in groundwater. (Phelps 2004 USGS Scientific Investigations Report ) Different Silver Springs vents/vent groups are fed by different source areas (deeper vs. shallow; different areas of springshed/flowpaths; etc.). (SJRWMD Special Publication SJ2008-SP6) Land use in the springshed nearest the spring has changed from predominantly natural to urban/agricultural over the past 50 yr; these land uses are the main sources of pollutant loading to groundwater and the springs. (SJRWMD Special Publication SJ2007-SP4)

7 Nitrate hotspots in Silver Springs Basin Groundwater Insightful Corp SJRWMD Special Publication SJ2008-SP20

8 Impaired Waters Rule Chapt , F.A.C. Impaired water shall mean a water body or water body segment that does not meet its applicable water quality standards.... due in whole or in part to discharges of pollutants from point or nonpoint sources. Ch (7), F.A.C.

9 Declining Spring Flows Two recent studies: Copeland et al (FGS) Wetland Solutions, Inc. 2010

10 Declining Spring Flows (Wetland Solutions, Inc. 2010)

11 Declining Spring Flow in Silver Springs From Fay Baird s talk in Nov 2010

12 Declining Water Quality Increased dissolved ions/salts Copeland et al. FGS Bulletin No. 69 Increased Nitrate-Nitrite Nitrogen (NOx-N or nitrate for short) Numerous studies throughout Fla.

13 Silver Springs Trends

14 NOx-N (mg/l or ppm) Nitrate levels in selected SJRWMD springs Volusia Blue Spring Silver Springs Juniper Spring 1.4 Silver Springs Date

15 Silver Springs 50-Year Retrospective Study Summer submerged aquatic vegetation biomass similar; winter biomass lower Epiphyte biomass increased ~3x Increase in algal mat biomass Species richness for birds, fish and reptiles similar Decline in fish biomass Decline in ecosystem Gross & Net Primary Productivity

16 Silver Springs 1950 s (Photo by Bruce Mozert) Odum 1957 notes large mats of macroalgae in Silver Springs, but these were... not large enough to figure in the overall community estimates. (of primary productivity)

17 Biomass (g DW/m 2 ) Silver Springs 50 Year Comparison Epiphyte biomass Nitrate concentration Year Source: Munch and others NOx-N (mg/l)

18 Silver Springs 2010

19 Silver Springs Projections N Loads and Nitrate concentrations Source: Munch and others 2007

20 Silver Springs Other Considerations Increased growth of algae and/or changes in algal communities may be impacting fauna of springs Nitrate may be exhibiting toxicity to species of aquatic fauna at levels seen in a number of springs throughout the state Proliferation of nuisance and toxic species of algae has been implicated in outbreaks of rashes and allergic reactions in folks swimming in springs

21 EPT Score Pollution-sensitive EPT invertebrate taxa may be lost with increasing amounts of nuisance algae EPT Score vs. % Cyanobacteria & Chlorophyta % Cyanobacteria + Chlorophyta Source: FDEP Bioassessment Program data SJRWMD Professional Paper SJ2009-PP1

22 Silver Springs Other Considerations Increased growth of algae and/or changes in algal communities may be impacting fauna of springs Nitrate may be exhibiting toxicity to species of aquatic fauna at levels seen in a number of springs throughout the state Proliferation of nuisance and toxic species of algae has been implicated in outbreaks of rashes and allergic reactions in folks swimming in springs

23 NOx-N (mg/l) Nitrate levels in selected Florida Springs & toxicity thresholds from the literature 6 Spring Shrimp protozoea Caddisfly early instar Lake trout development Gambusia embryo Frog 8 wk LOEC Statewide median Blue (Volusia) Weeki Wachee Silver Wekiwa Rainbow Manatee Blue (Lafayette) Troy Blue (Jackson) Fanning SJRWMD Professional Paper SJ2007-PP1

24 Silver Springs Other Considerations Increased growth of algae and/or changes in algal communities may be impacting fauna of springs Nitrate may be exhibiting toxicity to species of aquatic fauna at levels seen in a number of springs throughout the state Proliferation of nuisance and toxic species of algae has been implicated in outbreaks of rashes and allergic reactions in folks swimming in springs

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26 FDEP 2009 Report Silver Springs & River designated as impaired water Chapt FAC Elevated NOx Algal mats/smothering

27 NOx-N Concentration Targets Wekiva TMDL mg/l Wekiva PLRG 0.22 mg/l Suwannee basin springs TMDL 0.35 mg/l Wakulla Springs TMDL 0.35 mg/l EPA numeric criterion for springs 0.35 mg/l Silver Springs c 1950s - ~0.4 mg/l Preponderance of evidence indicates a NOx concentration of mg/l would be protective

28 Summary Silver Springs is important ecologically, historically and economically to the region The spring group has exhibited declines in flows over the past 50 years (most pronounced past 20 years). We need to assess trends in dissolved ions/salts to see if they are increasing. MFL work is re-analyzing all discharge data from Silver Springs group Many springs in the group exhibit elevated NOx-N concentrations and as a whole NOx levels have increased 20-fold over the past 100 years

29 Summary Changes in NOx levels (interacting with phosphorus and spring discharge) are linked to changes in spring ecology, including increased algal growth, reduced SAV cover/biomass, and potential impacts on aquatic fauna (habitat changes, toxicity,?) Various land uses and sources have been identified as contributors of N loading to ground water and springs; N comes from fertilizer, wastewater, and manure FDEP has placed Silver Springs group and the upper Silver River on the Verified Impaired Waters List