Contents

Cover
Title Page
Suggested Citation
List of Figures
List of Tables
Conversion Factors
Abbreviations
Abstract
Introduction
Purpose and Scope
Previous Studies
Acknowledgments
Site-Numbering System
Environmental Setting
Methods
Hydrologic and Water-Chemistry Data
Aquatic Community Data
Characterization of Springs
Silver Springs
Hydrology and Water Chemistry
Aquatic Communities
De Leon Spring
Hydrology and Water Chemistry
Aquatic Communities
Gemini Springs
Hydrology and Water Chemistry
Aquatic Communities
Green Spring
Hydrology and Water Chemistry
Aquatic Communities
Comparisons among Springs
Hydrology and Water Chemistry
Aquatic Communities
Summary
Selected References
Appendix A. Water-Chemistry Data, 2004
Appendix B. Compounds Commonly Detected in Wastewater
Appendix C. Pesticides Analyzed
Appendix D. Macroinvertebrate Taxa Reported in this Study
Appendix E. Scientific Names, Authorities and Dates of Original Descriptions, and Common Names of Fishes Reported in this Study

Figures

1. Map showing locations of Upper Floridan aquifer springs
2. Graph showing monthly rainfall at DeLand and Sanford, Florida, 1940-2004
3. Graph showing monthly rainfall at Ocala, Florida, 1940-2004
4. Photograph showing Silver Springs group
5. Graph showing discharge from the Silver Springs group, 1940-2004
6. Graph showing nitrate-nitrogen concentrations for Silver Springs, De Leon Spring, and Gemini Springs
7. Map showing location of De Leon Spring
8. Photograph showing De Leon Spring pool
9. Photograph showing De Leon Spring dam
10. Photograph showing view downstream from De Leon Spring to Spring Garden Lake
11. Graph showing discharge from De Leon Spring, 1965-2004
12.  Graph showing delta ¹⁸O of nitrate as a function of delta¹⁵N of nitrate for samples collected in 2004
13. Photograph showing periphyton sampler at De Leon Spring, August 11, 2004
14. Map showing locations of Gemini Springs and Green Spring
15. Map showing Gemini Springs
16. Photograph showing view from Gemini Springs to the dam and Lake Monroe
17. Graph showing total combined discharge from Gemini Springs, 1995-2004
18. Photograph showing Gemini Springs south vent
19. Photograph showing view toward old springhead at Gemini Springs
20. Photograph showing view toward Gemini Springs south vent
21. Photograph showing periphyton sampler at Gemini Springs near the dam, August 11, 2004
22. Map showing Green Spring
23. Photograph showing view from culvert to Green Spring pool
24. Photograph showing view from steps at Green Spring toward culvert
25. Graph showing Green Spring discharge, 2000-2004
26. Photograph showing Green Spring (water is murky)
27. Photograph showing Green Spring (water is clear)
28. Photograph showing sulfur-reducing bacteria form light gray plumes around the edges of Green Spring pool
29. Charts showing relative proportions of benthic invertebrates per order collected in De Leon Spring, Gemini Springs, and Green Spring, 2004
30. Diagram showing relative proportions of cations and anions in spring-water samples, 2004
31. Chart showing total number of all amphipods collected by season in De Leon Spring, Gemini Springs, and Green Spring, 2004
32. Chart showing total number of Gammarus sp. and Hyallela azteca by season at De Leon Spring, 2004

Tables

1. Wastewater compounds, pesticides, and number of detections, 2004
2. Dissolved gas and sulfur hexafluoride data
3. Fishes collected or observed in Silver Springs State Park, deposited in the Florida Museum of Natural History, and reported by Hubbs and Allen
4. Mussels collected in Silver River State Park and the Ocklawaha River at the mouth of the Silver River, 2002
5. Percent composition of total number of benthic macroinvertebrates collected in De Leon, Gemini, and Green Springs, 2004
6. Richness and community measures for De Leon Spring
7. Fishes observed or collected in De Leon Springs State Park, and deposited in the Florida Museum of Natural History
8. Richness and community measures for Gemini Springs
9. Richness and community measures for Green Spring

Conversion Factors

Temperature in degrees Celsius (^oC) may be converted to degrees Fahrenheit (^oF) as follows:

^oF=(1.8^oC)+32.

Temperature in degrees Fahrenheit (F) may be converted to degrees Celsius (^oC) as follows:

^oC=(^oF-32)/1.8.

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29).

Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).

Altitude, as used in this report, refers to distance above the vertical datum.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25^oC).

Concentrations of chemical constituents in water are given either in milligrams per liter (µmg/L) or micrograms per liter (µg/L).