## U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 

# Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida

Prepared in cooperation with the City of Jacksonville 

## 03–4299 By Shaun M. Wicklein

Tallahassee, Florida 2004

### For additional information Copies of this report can be purchased from: U.S. Geological Survey Branch of Information Services Box 25286 Denver, CO 80225-0286 888-ASK-USGS Use of trade, product, or firm names in this publicatio n is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey.

Additional information about water resources in Florida is available on the World Wide Web at **http://fl.water.usgs.gov** 

### write to: U.S. Geological Survey 2010 Levy Avenue Tallahassee, FL 32301 

## U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY Charles G. Groat, Director**Contents III** 

# CONTENTS

Abstract



### ............................................................................................................................... ..................... 1 Introduction



### ............................................................................................................................... ................ 2 Purpose and Scope.............................................................................................................. ......................................... 2 Description of Study Area ...................................................................................................... ..................................... 2 Data Collection and Analysis ................................................................................................... ................................... 4 Basin Characteristics .......................................................................................................... ................................................... 9 Fishing Creek.................................................................................................................. ............................................. 9 Big Fishweir Creek............................................................................................................. ......................................... 10 Streamflow..................................................................................................................... ........................................................ 10 Evaluation of Water Quality and Potential Effects of Sep tic Tank Effluent...................................................... .................... 13 Major Ions..................................................................................................................... ............................................... 14 Nutrients ...................................................................................................................... ................................................ 16 Wastewater Constituents........................................................................................................ ...................................... 18 Bacteria....................................................................................................................... ................................................. 19 Summary........................................................................................................................ ........................................................ 22 References ..................................................................................................................... ........................................................ 23 Appendixes Appendix 1: Constituents analyzed as part of major ion and nutrient sampling



### ....................................................... 25 Appendix 2: Constituents analyzed as part of the U.S. Geological Survey National Water-Quality Laboratory organic wastewater sample series............................................................................................... ....................................... 26 Appendix 3: Fecal coliform bacteria counts for su rface-water samples.....

.............. .............. .............. ............ ..................... 27 Appendix 4: Discriminant analysis of antibiotic resistance patterns used to classify fecal coliform bacteria from known sources into source categ ories for surface-water samples .........

.............. .............. ............ ........... ................ 28

FIGURES 1-3. Maps showing: 1. Location of study areas and selected monitoring sites in Jacksonville, Duval County, Florida ........

........... ..... 3 2. Streamflow and water-quality data collection sites for Fishing Creek basin, Jacksonville, Florida.................. 5 3. Streamflow and water-quality data collection s ites for South Branch Big Fishweir Creek basin, Jacksonville, Florida .......................................................................................................... ................................ 6 4-10. Plots showing: 4. Measured streamflow at data coll ection sites, Jacksonville, Florida, 200 0-2002.............................................. 12 5. Comparison of daily mean streamflow for OrtegaRiver near Jacksonville for the period of record, January 1, 1965, to September 30, 2002; January 1, 2000, to September 30, 2002; and daily mean streamflows for days on which measuremen ts were made at Fishing Creek at 110 thStreet and South Branch Big Fishweir Creek at Blanding Boulevard ................

.......................................................... ...... 12 6. Concentrations of dissolved sodium at data collection sites, Jacksonville, Florida.......................................... . 15 7. Concentrations of nitrogen species at data collection sites, Jacksonville, Florida.......................................... ... 16 8. Concentrations of total nitrogen at data collection si tes, Jacksonville, Florida............................................ ..... 17 9. Concentrations of total phosphorus at data collection sites, Jacksonville, Florida

.............. .............. .............. .. 18 10. Concentrations of fecal co liform bacteria at data collection sites, J acksonville, Florida .................................. 21

TABLES 1. Data collection and compilation sites, Jacksonville, Florida ................................................................ .................. 5 2. Subdivision and study basin characteristics, Jacksonville, Florida, 2000



### .................................................... 9 3. Residential water use, Duval County, Florida, 2002...

.............. .............. ........... ............ ........... .......... .................... 10**IV Contents** 4. Measured streamflow summary for datacollection sites, Jacksonville, Florida



### ............................................ 11 5. Rainfall summary for selectedsites in Jacksonville, Florida



### ..................................................................... 13 6. Summary of major ion constituent s from surface-water samples for Fishing Creek and South Branch Big Fishweir Creek, Duval County, Florida, 2000-02; the surficial aquifer system in Duval County, 1970-89; and selected surficial aqui fer wells in areas serviced by se ptic tanks, Dade County, Florida, 1970-73........................................................................................................................ ........................................... 14 7. Summary of nitrogen and phosphorus concentrations for surface-water samples, Jacksonville, Florida .... .......... 17 8. Concentrations of organic wastewater compound s above the minimum laboratory-reporting level, Jacksonville, Florida



### ........................................................................................................................ 19 9. Fecal coliform bacteria summary for surface-water samples, Jacksonville, Fl orida...........

........... ........... ........... .. 20 10. Summary of discriminant analysis of antibiotic resistance patte rns used to classify fecal coliform bacteria from known sour ces into source categories for surface-wa ter samples, Jacksonville, Florida



### ............... 21

CONVERSION FACTORS AND VERTICAL DATUM

Temperature in degrees Fahrenheit ( ° F) may be converted to degrees Celsius ( ° C) as follows: ° C=( ° F-32)/1.8.

Horizontal coordinate information (latitude-longitude) is re ferenced to the North American Datum of 1983 (NAD83).
Acronyms and abbreviations: JEA Jacksonville El ectric Authority μ

g/L micrograms per liter mg/L milligrams per liter mpn/100mL most probable number per 100 milliliters NPDES National Pollutant Discharge Elimination System NURP Nationwide Urban Runoff Project USGS U.S. Geological Survey **Multiply By To obtain**
Length inch (in.) 2.54 centimeter

foot (ft) 0.3048 meter mile (mi) 1.609 kilometer

Area acres (ac) 0.4047 hectare square mile (mi 2 ) 2.590 square kilometer

Flow Rate cubic foot per second (ft 3 /s) 0.02832 cubic meter per second million gallons per day (Mgal/d) 0.04381 cubic meter per second inch per year (in/yr) 25.4 millimeter per year**Abstract 1** 

# Evaluation of Water Qualit y for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida

By Shaun M. Wicklein

**ABSTRACT** Tributary streamflow to the St. Johns Riverin Duval County is thought to be affected by septic tank leachate from resi dential areas adjacent to these tributaries. Water managers and the city of Jacksonville have committed to infrastructure improvements as part of a management plan to address the impairment of tributary water quality. In order to provide data to evaluate the effects of future remedial activities in selected tributaries, major ion and nutrient concentrations, fecal coliform concentrations, de tection of wastewater compounds, and tracking of bacterial sources were used to document septic tank influences on the water quality of selected tributaries. The tributaries Fishing Creek and South Big Fishweir Creek were selected because they drain subdivisions identified as high priority locations for septic tank phase-out projects: the Pernecia and Murray Hill B subdivisions, respectively. Population, housing (number of residences), andseptic tank densities for the Murray Hill B subdivision are greater than those for the Pernecia subdivision. Water-quality samples collected in the study basins indicate influences from ground water and septic tanks. Estimated concentrations of total nitrogen ranged from 0.33 to 2.86 milligrams per liter (mg/L), and ranged from less than laboratory reporting limit (0.02 mg/L) to0.64 mg/L for total phosphorus. Major ion concentrations met the State of Florida Class III surface-water standards; total nitroge n and total phosphorus concentrations exceeded the U.S. Environmental Protection Agency Ecoregion XII nutrient criteria for rivers and streams 49 and 96 percent of the time, respectively. Organic wastewater compounds detected at study sites were categorized as detergents, antioxidants and fl ame retardants, manufactured polycarbonate resins, industrial solvents, and mosquito repellent. The most commonly detected compound was para-nonylphenol, a breakdownproduct of detergent. Results of wastewater sampling give evidence that stream water in the study basins is affected by septic tank effluent. Fecal coliform bacteriaconcentrations were measured on a monthly basis; of 115 samples, 63 percent exceeded the State of Florida fecal coliform bacteria standard for Class III surface waters of 800 colonies pe r 100 milliliters of wateron any 1 day. Fecal coliform bacteria concentrations ranged from less than 20 colonies per 100 milliliters of sample to greater than or equal to 160,000 colonies per 100 milliliters of sample. Antibiotic resistance patt erns of fecal coliform bacteria were used to identify the sources of fecal coliform bacteria. Significant sources of fecal coliform bacteria included wild animals, dogs, and humans. A majority of the fecal coliform bacteria were classified to be from human sources. Because the primary source of fecal coliform bacteria is from human sources, and most likely septic tank effluent, manage ment of human sources may substantially improvemicrobiological water quality in both the Fishing Creek and South Branch Big Fishweir Creek basins.**2 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** 

### INTRODUCTION
Water managers in the lower St. Johns River basin and the city of Jack sonville are committed to improve the quality of waterways that contribute flow to the St. Johns River, an American Heritage River. The quality of tributary streamflow to the St. Johns River in Jacksonville is thou ght to be affected by septic tank leachate from reside ntial areas adjacent to thetributaries (Dana Morton, city of Jacksonville, Division of Air and Water Quality, oral commun., 1999). Shallow ground water in thes e areas likely is the vehicle that transports fecal coliforms and nutrients fromseptic tank leachate to the surface water. The installation of sanitary sewer system s in the city of Jacksonville for areas presently on septic tank systems is one step being taken to cleanup waterways (City of Jacksonville, 2000).Although research has been done on the efficiency of septic tank systems to treat wastes, and the deterioration of these system s over time has been studied, the effect of the removal of septic tank systems on the receiving ground and surface waters has not been widely studied. Documentation of water-quality conditions prior to and after re placement of septic tank systems by a centralized syst em is needed to evaluate the effects of remedial activities. The associated hydrologic conditions under which the water quality is evaluated should be documented to isolate the impact of the septic tank removal from other factors that can affect water quality. The study of environmental effects of septic tank removal will help to further the understanding of human imp acts on water quality in river systems.The U.S. Geological Survey (USGS), in cooperation with the city of Jacksonville Air and Water-Quality Division, began a 4-1/2-year study to evaluate the effects of septic tank removal on two tributaries to the St. Johns River in April 1999. The tributaries Fishing Creek and Big Fishweir Creek were selected because they drain neighborhoods identified by JacksonvilleElectric Authority (JEA) as priority locations for septic tank phase-out projects (fig. 1). The neighborhoods are the Pernecia and Murray Hill B subdivisions, which coincide with Fishing Creek and Big Fishweir, respectively.Major ion and nutrient concentrations, detections of organic wastewater compounds, and fecal coliform concentrations were documented in order to evaluate the effects of septic tank removal projects on stream water quality. Bacterial source tracking, as described by Harwood and others (2000), was included in sampling efforts to further define septic tank influence on the water quality of the tributaries.



### Purpose and Scope
The objective of this study was to evaluate the effects on water quality in two tributaries to the St. Johns River resulting from the replacement of residential septic tank systems by a centralized sewer system. The study, as planned, was divided into two phases. The first phase was to document baseline water-quality conditions prior to connection of targeted areas (fig. 1) to a centralized sewer system.The second phase was to document changes in waterquality constituent concentrations that may result from installation of sanitary sewer systems and removal of septic tank systems in targeted areas. Unforeseen delays, however, in the inst allation of sanitary sewer systems affected evaluatio n of hydrologic and waterquality conditions following planned sanitary sewer system installation. This report, therefore, documents baseline hydrologic and water-qualityconditions occurring in 2000-2002 prior to removal ofseptic tanks and installation of a sanitary sewer system. Basin characteristics are documented to facilitatetransferability of results to other locations. The resu lts of sampling for major ions (semi-annually), nutrients (quarterly), organic wastewater compounds (annually) and fecal coliform bacteria (monthly) at two sites in each basin are summarized along with streamflow measurements(quarterly). Bacterial source tracking, used to determine the source of fecal coliform bacteria, is described.



### Description of Study Area
The geologic deposits important to this study include the sediments from land surface to a depth of about 100 feet (ft). The sediments consist mostly of unconsolidated fine to medium grained quartz sand with some clay, shell, and limestone. These unconsolidated sedi ments form the surficial aquifer system. Throughout most of Duval County, the water table in the surficial aquifer system is within 5 ft of land surface (Causey, 1975). Locally, the depth to water is about 10-12 ft. The surficial aquifer system is rechar ged primarily by rainfall.**Introduction 3 MAYPORT**  **FORT GEORGE ISLAND** 

**MANDARIN ATLANTIC**  **BEACH**

**JACKSONVILLE BEACH**  **JACKSONVILLE**

**NEPTUNE BEACH**  S

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Intra-coastal

waterway

C e d a r R i v e r 

### DUVAL COUNTY

**CLAY COUNTY BAKER COUNTY** 

**ST. JOHNS COUNTY NASSAU COUNTY**  95

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Base modified from U.S. Geological Survey digital data, 1:100,000, 1985 Albers Equal-Area Conic projection DUVAL COUNTY

STUDY AREA

FISHING CREEK BASIN SOUTH BRANCH BIG FISHWEIR CREEK BASIN ¤

¤ 1

2 p

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2 EXPLANATION

RAINFALL MONITORING SITE AND NUMBER

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MONITORING SITE AND NUMBER

**Figure 1.** Location of study areas and selected monitoring sites in Jacksonville, Duval County, Florida (site numbers refer to table 1).**4 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** 

### Discharge from the surficial aquifer system occurs by evaporation, transpiratio n by plants, seepage into surface-water bodies, leakage into the underlying rocks, and from discharging wells. Underlying the surficial aquifer system are about 400 ft of mostly fine-grained, clay sediments that also include some shell, sand, or limestone. These sediments make up the intermediate confining unit. Underlying the intermediate confining unit is a thic k sequence (greater than 1,600 ft) of carbonate rock s that form the artesian aquifer system (Phelps, 1994). The topography of Duval County is controlled by a series of ancient marine terraces (Cooke, 1945) that were formed due to glacial activity during thePleistocene Epoch when the sea was relatively stationary at various levels higher than present-day sea level. Six marine terraces are recognized in Duval County: the Coharie, Sunderland, and Wicomico terraces that range in altitude from 215 to 70 ft in the western part of the county; the Penholoway and Talbot terraces that form a coastal ridge at altitudes from 70 to 25 ft; and the Pamlico terrace at a ltitudes below 25 ft, which forms the low coastal plain throughout most of the eastern and central parts of the County (Anderson, 1972). The study areas occur at elevations associated with the Talbot and Pamlico terraces. Much of thestudy areas likely were barrier islands during deposition of the Talbot Formation (Cooke, 1945). Soils in the study areas generally are somewhat to very poorly drained. Sandy and loamy sediments are present on rises, knolls, an d flats. Creek bottoms are made up of very poorly and poorly drained Surrency soil types that are present in nearly level depressions and on flood plains (U.S. Department of Agriculture, 1998). The upland soil types generally are fine sands of Pelham, Mascotte, and Sapelo, which are poorly drained and present on nearly level flats and flatwoods. About 75 square miles (mi 2 

### ) of surface water covers parts of Duval County (the County has a total area of about 840 mi 2 

### ). Two major rivers and their tributaries drain the County: the St. Johns River and the Nassau River. Numerous smaller streams drain to the Intra-coastal waterway or the Atlantic Ocean. Because parts of the County are relatively flat, some drainage divides in low areas are indistinct. During high-flow conditions, water can discharge into another drainage basin. The average runoff for streams in the County is about 50 percent greater than that of the State for Florida, as a whol e (Anderson, 1972). This likely is a result of imperm eability of sediments underlying the surficial aquifer system in Duval County. The climate of Duval County is humid subtropical and is characterized by long, warm, humid summers and mild winters. Freezing temperatures may occur during the winter months, but are rare because Duval County borders the Atlantic Ocean and is close to theGulf Stream, which produces moderate winter temperatures. In an average year, about 65 percent of the total annual precipitation occurs fro m June to October, with the remaining precipitation mo re or less evenly distributed throughout the remainder of the year. Typical weather patterns for Duval County include frontal activity during the winter months, causing widespread rainfall and short periods of cooler temperature, and scattered thunderstorm activity during the summer months. The 100-year, 1868-1967, average rainfall recorded at Jacksonville wa s 51.52 inches (Anderson, 1972).Rainfall represents the largest input of water tothe study areas, and is the main climatic factor affecting the variation in surface-water flows for Duval County. Water supplied by rainfall is depleted by runoff, evapotranspiration, an d seepage to the aquifers. In most parts of Duval County, 10-16 inches of rainfall enters the surficial aquifer sy stem in a year (Anderson, 1972). The amount of water that passes through the surficial aquifer to the Floridan aquifer probably is insignificant because artesianflow conditions exist in the eastern two-thirds of the County, and because numerous swampy areas indicate poor subsurfacedrainage. Thus, in most parts of the County, the majority of the water that enters the surficial aquifer system leaves the aquifer as seepage to streams, and by evapotranspiration. Therefore, the amount of runoff generally is the difference between rainfall and evapotranspiration.



### Data Collection and Analysis
Two basins were selected for this study: Fishing Creek (fig. 2) and South Branch Big Fishweir Creek (fig. 3). Surface-water-quality sampling sites were selected at two locations ineach of the study basins: one upstream and one downstream from the area in which a sanitary sewer system will be installed and septic tanks will be remove d (table 1). Water-quality data were collected monthl y to document conditions prior to the installation of a sanitary sewer system (and subsequent discontinuation of septic tank use). Streamflow measurements were made at the time of sampling events (quarterly).**Introduction 5 Table 1.**  Data collection and compilation sites, Jacksonville, Florida [NOAA, National Oceanic and Atmospheric Administration; NLMOF, Naval Atlantic Meteorology and Oceanography Facility Jacksonvill e, Florida; USGS, U.S. Geological Survey. Data type: R, rainfall; D, discharge; P, periodic water-quality; --, not available; NA, not applicable. Map number shown in figures 1, 2, and 3]

**Map number**  **Site name and**  **identification number Latitude Longitude**  **Drainage**
**area a**  **(square miles)** 

aDrainage area from U.S.Geological Survey, 2003, Water re sources data, Florida, water year 2002, volume 1A. **Data type**  **Source of data** 

1 Jacksonville International Airport (084358) 30° 30' --" 81° 42' --" NA R NOAA

2 Naval Air Station Jacksonville (722065) 30° 14' --" 81° 40' --" NA R NLMOF

3 Ortega River at Jacksonville (02246300) 30° 14' 50" 81° 47' 49" 30.9 D USGS

4 Fishing Creek at Wesconnet Boulevard (02246435) 30° 14' 10" 81° 44' 22" .76 D, P USGS
5 Fishing Creek at 110 thStreet (0226437) 30° 14' 27" 81° 43' 57" 1.27 D, P USGS

6 South Branch Big Fishweir Creek at Casssat Avenue (02246465) 30° 17' 35" 81° 43' 51" .43 D, P USGS

7 South Branch Big Fishweir Creek at Blanding Boulevard (02246467) 30° 17' 35" 81° 43' 27" .67 D, P USGS BASIN BOUNDARY 295

Astrid Dr. Penny La.

Coffey La. Jonnie Cir. W. Jonnie Cir. E. Elemgrove Ave..

Viola La. Seaboard Ave..

111th St. Goodman Rd.

Anderson Rd. Nancy Dr. Joy Dr. S. Joy Dr. W. Pernecia St. Hilda St. Karen St. Judy Dr. Oaklane Dr. Nora Rd.

Aline Rd. Blanding Blvd. Gaskins Rd.

Kohn St .

118th St.

Turnett Rd. Jammes Rd. Erma St. Flowers Ave.

120th St. 118th St.

Ortega Park Blvd. Vista Verde St.

Morse A ve.

Ovella Rd.

Hurdia Rd. 105th St.

110th St. Wesconnet Blvd.
Fishing Creek SAND PIT 

### p p

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0 .25 .5 KILOMETER

Base modified from U.S. Geological Survey digital data, 1:100,000, 1985 Albers Equal-Area Conic projection STUDY AREA DRAINAGE

BASIN DUVAL COUNTY PERNECIA SUBDIVISION EXPLANATION

HYDROLOGY WETLANDS

p

4 DISCHARGE AND WATER-QUALITY MONITORING SITE AND NUMBER STREAMFLOW DIRECTION

**Figure 2.** Streamflow and water-quality data collection sites for Fishing Creek basin, Jacksonville, Florida (site numbers refer to table 1).**6 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** BASIN BOUNDARY Cd

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.5 MILE .25 0

0 .25 .5 KILOMETER Base modified from U.S. Geological Survey digital data, 1:100,000, 1985 Albers Equal-Area Conic projection Mikael A ve. Garth Ave.

Astral St. Normandy Blvd.

Attleboro St. Truman A ve. Lois A ve.

Pangola Dr . Comanche St. Moha wk St. Denaud St. Alta Vista St. Labelle St. Seba St. Velma St.

Redr ac St. Orton St. Bagnal Rd.

Carder St. Hollycrest Dr

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Woodcrest Rd.
Poppy Dr.
Royce A ve.

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Coronet Dr

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Glenw ood A ve. Mull St. Pangola Dr . Neva St. Orton St. Ellis Rd. S. Weeks Rd.

Lasota A ve. Radio Ln.

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. Park St. Wyn St.

Camille A ve.

Janice Cr . S.

Marelene A ve. Golfvie w St. Indberg Dr . Iniblick Dr .

Hyde Gro ve

Ave. Vista A ve. Hyde Park Cr.

Lexington A ve. Shirley Ave. Irvington A ve. Beverly Cr

. Apap

Apap Cardinal Blvd.

Sefa Cr . N. Shelb y Ave. Merr imac A ve.

St. Johns A ve.

Roose velt Blvd. Fair St. Blanding Blvd. Wheeler Ave. Fishweir Ave. Stimson St. Dakar St.

Yerkes St. Amherst St. Tunis St. Jersey St. Ellis Rd. S. Post St. Polaris St. French St. Kerle St. Lawnview St. Sappho Ave. Ingleside Ave. Whole St. Dancy St. Antisdale St.

Lark St. Scotten Rd. Woodr uff Ave. Randolph St. Kingsbury St. Hercules Ave. Alpha Ave. Delta Ave. Woolman Ave. Plymouth St. Woycoff A

ve.

Ather ine Te.
Lizabeth Te.
Louisa Te. Eadle y Te.
Prunty A ve. Hamilton St.

Lamboll A ve. Cassat A ve. Weeks Rd. Plymouth Pl. Lake Shore Blvd.

DRAINAGE

BASIN DUVAL COUNTY STUDY AREA 

### p p 6
7 EXPLANATION HYDROLOGY

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6 DISCHARGE AND WATER-QUALITY MONITORING SITE AND NUMBER STREAMFLOW DIRECTION

MURRAY HILL B SUBDIVISION

**Figure 3.** Streamflow and water-quality data collection sites for South Branch Big Fishweir Creek basin, Jacksonville, Florida (site numbers refer to table 1).**Introduction 7**

### In order to describe basin characteristics, information on the size of drainage areas, soil characteristics (soil type and drainage characteristics), land use, septic tank and housing de nsity, and water use in the area (from utility records) were compiled. These basincharacteristics aided in the interpretation of waterquality data, and also will help with the transferability of the results to other areas where sanitary sewer systems are to replace septic tanks. Water samples were collected at four sites (figs. 2 and 3) during 2000 -2002. Samples for majorions were collected semi-annually during wet (JuneOctober) and dry (November-May) seasons. Nutrient samples were collected quarterly at times when two of the quarterly sampling even ts corresponded to the semi-annual sampling events. Large nutrient loads can be transported during storm events, and it is possible that nutrients from septic tank drain fields might be flushed out of the ground-water system at these times. For this reason, major ion and nutrient samples also were collected for three storm events during the study period. Four water samples were collected at each site and analyzed for organic compounds commonly foundin wastewater. Three of the four samples were collected during low-flow and one during a storm event. Fecal coliform bacteria samples were collected monthly. Water samples also were collected four times during the study and analyzed for antibiotic resistance patterns used to classify fecal coliform bacteria sources. All samples werecollected according to methods presented in the USGS National Field Manual for the Collection of Water-Quality Data (Wilde and others, 1998). Streamflow was measured at each site when collecting quarterly water-quality samples and duringstorm events. Measurements were made using conventional current meter methods described by Rantz and others (1982). Field properties, consisting of water temperature, specific conductance, dissolved oxygenconcentration, and pH, were measured using a multiparameter water-quality mete r calibrated according to the meter’s operational manu al and methods described by Wilde and others (1998) . Field measurements were made whenever water samples were collected. Water samples collected during the study were sent to several laboratories for analysis. Major ions and nutrients were analyzed at the USGS Ocala Water Quality and Research Laboratory in Ocala, Florida,according to methods presented in Fishman and Friedman (1989) and the U.S. Environmental Protection Agency (2003). Constituents analyzed as part of the major ion and nutrient sampling are listed inappendix 1. Samples for analyses of organic wastewater compounds were proces sed at the USGS National Water-Quality Laboratory in Denver, Colorado, according to methods presented in Zaugg and others (2002). Compounds analyzed included alkylphenol ethoxylate nonionic surfactants and their degradates, food additives, fragrances, antioxidants, flame retardants, plasticizers, industri al solvents, disinfectants, fecal sterols, polycyclicaromatic hydrocarbons, and high-use pesticides (app. 2). Samples collected for fecal coliform bacteria anal yses, using the most-probable-number method, were analyzed at the Florida Department of Health laboratory in Jacksonville, Florida, according to method s presented in Clesceri and others (1998, p. 9-48). Antibiotic resistance patterns of fecal coliform bacteria from water samples were analyzed by the Department of Biology, University of South Florida,Tampa, Florida, using materials, methods, and statistical analysis described by Harwood and others (2000). Water samples were collected at sites, chilled to 4 degrees Celsius, and shipped to the University of South Florida. Fecal coliform bacteria were isolatedfrom water samples within 8 hours of sample collection by membrane filtration using mFC agar. Aknown-source library of fecal coliform bacteria isolates was used for classification of fecal coliform bacteria isolated from water samples (Harwood and others, 2000). The library was developed in the Jacksonville area from appr oximately 1998-2000 and contains 1,777 human-origin fecal coliform bacteria isolates and 4,367 animal-o rigin fecal coliform bacteria isolates. Wiggins and others (2003) concluded that a multi-watershed library of at least 2,300 samples isneeded for reliable classification of fecal coliform bacteria within the region of co llection. The library used for this study contains 6,144 fecal coliform bacteria isolates, which were collectedin the Jacksonville area. The library is not representative of all wildlife, but contains 337 fecal coliform bacteria isolates from a limited number of species: rabbits, racoons, ducks, wood storks, night heron, and egrets. This library was considered acceptable to use for this study. The antibiotic resistance patterns of fecal coliforms isolated from stream-water samples were determined using eight antibiotics: amoxicillin, gentamicin, cephalothin, ofloxacin, erythromycin,**8 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** 

### tetracycline, moxalactam, and chlortetracycline (Dr. Valerie Harwood, Department of Biology, University of South Florida, written commun., 2002). Discriminant analysis was used to classify individual sample isolates into groups on the basis of the valuesof several classification variables (Harwood and others, 2000). Fecal coliform bacteria isolates were categorized into one of five potential sources: chicken, cow, dog, human, and wild animal. Results from the analysis of antibiotic re sistance patterns of fecal coliform bacteria are assessed for accuracy of fecal coliform bacteria isolates classification by comparing to known sources. The rate of correct classification of fecal coliform bacteria isolates from known sources gives an indication of how accurately sample results represent the actual source of fecal coliform bacteria.Isolates of fecal coliform bacteria were correctly classified from known sources for a two-way split at a rateof 69 percent for human sources and an average correct classification rate of 78 percent for combined animal sources and for a six-way split at a rate of 54 percent for human, 57 percent for chicken, 54 percent for cow, 95 percent for dog, 72 percent for swine, and 51 percent for wild animal sources (Harwood and others, 2000). Water samples for this study were split into five classification catagories (chicken, cow, dog, human, and wild animal) that likely would produce a correct classification rate less than that of a two-way split and similar to a six-way split. Given the type of bacteria isolated (fecal coliform) and the database used for discriminant analysis of fecal coliform bacteria isolates, the probability of fecal coliform bacteria isolates being assigned to any one of the classification categories by chance alone is 20 percent. The probability of chance classification (20 percent) of fecal coliform bacteria isolates was considered the lower limit for considering any one source category to be a significant contributor of fecal coliform bacteria to the water. Quality-assurance procedur es were followed for collection and processing of water-quality samples. These procedures included checking and calibrating equipment daily as well as collecting additional samples for quality control. An alysis of quality-assurance samples provided information on the potential for sample contamination during collection, processing, and laboratory analysis. Quality-assurance sample s consisted of one field blank and three duplicate samples for major ions, one field blank and six duplicate samples for nutrients (nitrogen and phosphorus species), one field blank andtwo duplicate samples for analyses of organic wastewater compounds, and six field blanks for bacteria. Water samples for quality co ntrol were collected on randomly selected days at randomly selected sites during the study period. Field blanks provide information on possible contamination introduced to the sample during collection and processing (handlin g) of the sample in the field. Field blank samples were prepared by pouring water certified to be free of the analytes of interest through all sampling equipmen t as if an environmental sample was being processe d. Constituent concentrations for field blank samp les were less than the method-reporting limits for all samples. Duplicate quality-assurance samples were collected simultaneously with scheduled water samples, and were processed using the same equipment for both samples. Collection of duplicate samp les provided information on the uniformity of samplehandling in the field and sample processing by the laboratory. The small nature of the duplicate data set, six or less sample sets per constituent family, did not allow for an acceptable statistical comparison of quality-assurance and environmental water sample s. Constituent concentrations for duplicate quality-assurance samples and environmental water samp les were compared. The comparison indicated no contamination due to collection, handling, or processing.Data were graphically compared and statistically tested to evaluate whether any differences in constituent concentrations were observed between sites and basins. Data wereanalyzed for similarities and differences between up stream and downstream sites. Basin characteris tics were evaluated along with the water-quality datato determine possible relations between observed water-quality constituent concentrations.Summary statistics are presented and a nonparametric rank sum test (Helsel and Hirsch, 1992) was used to determine whether differences between sites in the study areas werestatistically significant. The rank sum test makes noassumption about the data distribution and was used because the data were not normally distributed. The rank sum test uses a statistic called a p-value. When the p-value is less than the chosen confidence level (in this study, 0.05), sample populations are considered st atistically different. The lower the p-value, the more significant the difference.**Basin Characteristics 9** 

### BASIN CHARACTERISTICS
Duval County originally was comprised of many small towns and uninco rporated areas, each with its own public services and infrastructure. In the 1970’s the small towns and unincorporated areas in Duval County were combined into the unified city of Jacksonville. As a result, the city of Jacksonville contained many areas that had little or no centralized public water or sanitary sewer systems. The two neighborhoods of interest to this study, the Pernecia and Murray Hill B subdivisions, consist of residences serviced by individual septic tank systems. As part of infrastructure improvements addressed by the Better Jacksonville Plan (City of Jacksonville, 2000), thesesubdivisions were scheduled for installation of sanitary sewer systems and removal of septic tank systems. The Pernecia and Murray Hill B subdivisions are suburban residential ne ighborhoods that are intersected by the study basins, Fishing Creek and South Branch Big Fishweir Creek, respectively (figs. 2 and 3). Both subdivisions contain single-family homes, duplexes, and some small-business development along the major four-lane roadways . Greater than 90 percent of the land use in each basin is single- or multi-family residences located along tw o-lane streets with swale drainage ditches (Amy McGr ath, Jacksonville Electric Authority, written commun., 2002). The Pernecia subdivision covers an area of about 193 acres, of which 156 acres drain to Fishing Creek. The Murray Hill B subdivision is about 465 acres, of which 154 acres drain to South Branch Big Fishweir Creek. The population and number of residences and septic tanks in the Pernecia and Murray Hill B subdivisions are provided in table 2. Exact totals for residential water and sewer usage for the Pernecia and Murray Hill B subdivisions are difficult to obtain because residences are serviced by individual water supply wells and septic tank systems. Study area reconnaissance indicated that no National Pollutant Discharge Elimination System (NPDES) permitted discharges exist within or upstream from the study basins and no point-source discharges were observed in the study basins (Dana Morton, city of Jacksonville, Division of Air and Water Quality, oral commun., 2002). Records of the JEA (2002) indicate that the average annual water and sewer usage per residence was about 10,700 and 8,860 cubic feet, respectively, between October 1, 2001, and September 30, 2002 (table 3). These numbers are based on the Duval County average and likely represent the average usage for any one residence during the year sampled. Given the diversity of residences accounted for in the JEA (2002) report, it is likely that the average water and sewer usages presented in table 3 are representative of the Pernecia and Murray Hill B subdivisions.



### Fishing Creek
The Fishing Creek basin (figs. 1 and 2) is located west of the St. Johns River and joins the Ortega River south (upstream) of its confluence with the Cedar River. Land areas in the basin generally arelow lying with little topographic relief. The downstream end of the study area is located approximately 2 miles upstream from the co nfluence with the Ortega River. The Fishing Creek study basin has a drainage area of 812.8 acres and contains 156 acres of the Pernecia subdivision.

**Table 2.** Subdivision and study basin characteristics, Jacksonville, Florida, 2000 [Source of data: Amy McGrath, Jacksonville Electric Authority, written commun., 2002]

**Subdivision Associated**  **study basin**  **Study basin drainage area**  **(acres) Subdivision**  **Intersecting**
**area a**  **(acres) Area**  **(acres) Population**  **(count) Residences**  **(count) Septic tanks**  **(count)**

Pernecia Fishing Creek 812.8 193.2 522 246 251 156

Murray Hill B South Branch Big Fishweir Creek 428.8 464.8 2,766 1,077 1,245 154

a Area within the subd ivision that drains to the study basin.**10 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** 

### Upland areas in the Fi shing Creek basin that drain to the stream channel tend to be relatively low and flat. The creek generally is narrow, 25 ft or less inwidth, with definitive banks that are 3-6 ft high, especially in the lower reaches of the basin. During highflow conditions, the stream has overflowed its banks and spread into the adjacen t neighborhood; conversely, during extended droughts, the stream has become intermittent for extended periods. Two distinct areas can be characterized in the Fishing Creek study basin: the western part of the basin upstream from Blanding Boulevard, and the northeastern part of the basin downstream from Blanding Boulevard. In theupstream part of the basin, west of Blanding Boulevard, the stream channel flows through densely wooded areas and becomes poorly defined, expanding into low-lying swampy areas. The upstream part of the basin is less populated, espe cially in the far westernpart. East of Blanding Boulevard, the channel is welldefined and meanders through a wooded riparian zone in a moderately populated suburban residential area (the Pernecia subdivision). Based on 2000 data (table 2), population, housing (number of residences), and septic tank densities fo r the Pernecia subdivision were 2.7 people per acre, 1.3 houses per acre, and1.3 septic tanks per acre, respectively. Due to the nonuniformity of housing distribution in the basin, densities likely are larger for areas in the northeastern part of the basin where the Pernecia subdivision is located.



### Big Fishweir Creek
The Big Fishweir Creek basin (figs. 1 and 3) is located west of the St. Johns River and joins the Ortega River at its confluen ce with the St. Johns River. The North and South Branches of Big Fishweir Creek come together approximately 0.75 miles (mi) upstream from the mouth. The study basin is located on the South Branch of Big Fishweir Creek less than 0.25 mi upstream from the confluence of the North **Table 3.** Residential water use, Duval County, Florida, 2002

**Usage type**  **Average usage for individual accounts a** 

aBased on Jacksonville Electric Authority 2002 Annual Report. **Annual (cubic feet)**  **Daily (cubic feet)**  **Daily (gallons)** 

Water 10,700 29.3 219
Sewer 8,860 24.3 182 

### and South Branches. Land areas within the basin generally are low-lying with moderate topographic relief. The South Branch Big Fishweir Creek study basin has a drainage area of 428.8 acres and contains 154 acres of the Murray Hill B subdivision. The South Branch Big Fishweir Creek is narrow, 20 ft or less, with banks approximately 3-5 ft high. The stream channel is modified throughout the basin and has sections of man-made channel armoring in the upper and middle reaches between Lakeshore Boulevard and Park Street. The channel in the upper reaches of the basin has been straightened and is deeply incised for drainage purposes. The basin divide in the upper basin is poorly defined because in this area the creek is connected to the Cedar River basin to the west. The riparian zone of the creek generally is lightly wooded and characterized by grassy areas common in suburban back yards. The South Branch Big Fishweir Creek is not known to be intermittent; a small amount of base flow generally is present even during extended dry periods. High flows usually are contained within the banks except during extreme events. Upland areas draining to the stream channel in the South Branch Big Fishweir Creek basin have greater slope than those in the Fishing Creek basin, especially in the lower part s of the basin. Based on 2000 data (table 2), population, housing (number of residences), and septic ta nk densities for the Murray Hill B subdivision were 6.0 people per acre, 2.3 houses per acre, and 2.7 septic tanks per acre, respectively.



### STREAMFLOW

Measurements of streamflow were made approximately quarterly when water-quality samples were collected and during storm events. The measured flows ranged from 107 cubic feet per second (ft 3 

### /s) at Fishing Creek at 110th Street to 0.02 ft 3 

### /s at the South Branch Big Fishweir Creek at Cassat Avenue (table 4). Three of the four measurement sites had two or more observations of no flow. The only site where no-flow conditions were not observ ed was the South Branch Big Fishweir at Cassat Avenue site. The downstream site on the South Branch of Big Fishweir Creek (at Blanding Boulevard) had two observations of no flow, but these observations were noted as being caused by backwater from debris. It is likely that a small amount of flow occurred at the observation times at the South Branch of Big Fishweir Creek at Blanding Boulevard site.**Streamflow 11**

### Measured streamflows for Fishing Creek generally were greater than th ose for South Branch Big Fishweir Creek, and in both basins streamflow increases from upstream to downstream (fig. 4). Based on calculations from period ic streamflow measurements, the runoff per unit area is greater in the FishingCreek basin. However, the South Branch of Big Fishweir basin has a higher housing density, which generally would result in increase d runoff per unit area, so it is possible that soil types and inflow from the surficial aquifer are the causes of increased runoff per unit area in the Fishing Creek basin. Streamflow measurements were somewhat evenly distributed throughout the range of flows measured (fig. 4). The relatively small (14 or less per site) number of streamflow measurements made during the study period can easily be skewed from the normal distribution of measurements by outliers. Skew in the measured streamflows is indicated at the FishingCreek at Wesconnet Boulevard site where 11 measurements were made, 2 of which were during storm events. This tended to bias percentiles of the sample set above the median streamflow, although a majority of flows were measured at less than 0.50 ft 3 

### /s. Streamflow was not measured continuously at sites, and it was unknown whether periodically measured streamflows were representative of the range of hydrologic conditions that may occur at study sites. Comparisons were made at a continuous-monitoring streamflow site at the Ortega River at 103rd Street near Jacksonville (map number 3, fig. 1) to determine whether periodically measured streamflows were representative of the rang e of hydrologic conditions during the study. Both of the study basins lie east of the drainage area included at the Ortega River at 103rd Street site, but the site is close enough to the study basins that the observed hydrologic conditions are considered representative of those at the study sites. A comparison of daily mean streamflows provides an indication of the range of hydrologic conditions observed at study sites (fig. 5). Daily streamflows observed during the study period (January 1, 2000, to September 30, 2002) tend to be less then those observedover the period of record (January 1, 1965, to September 30, 2002) at the Ortega River at 103rd Street site. Th is is consistent with the below-average rainfall observed during the study period (table 5). The medi an for days when samples were taken at Fishing Creek and South Branch Big Fishweir Creek closely represents the study period and long-term medians. The range of conditions for sampled days is slightly less than that for the study period and long-term period of record. Given the small number of streamflow observations at sampling sites,the observed hydrologic conditions represent the longterm hydrologic cond itions fairly well. **Table 4.** Measured streamflow summary for data co llection sites, Ja cksonville, Florida [USGS, U.S. Geological Survey; discharge va lues are in cubic feet per second; e, esti mated. Map number shown in figures 1, 2, and 3]

**Map number**  **Site name and**  **USGS identification number Number**  **of**
**measure**

**ments Maximum**  **measured discharge**  **Date Minimum**  **measured discharge**  **Date Observations**  **of no-flow** 

4 Fishing Creek at Wesconnet Boulevard (02246435) 11 75.4 9/15/2001 .07 9/5/2000 7

5 Fishing Creek at 110 thStreet (0226437) 13 107 9/15/2001 .07 7/11/2000 4

6 South Branch Big Fishweir Creek at Casssat Avenue (02246465) 14 9.87 9/15/2001 .02 7/11/2000 0

7 South Branch Big Fishweir Creek at Blanding Boulevard (02246467) 13 15.9 9/15/2001 .10e 6/12/2000 7/11/2000 2 a

aNo observable or measurable flow due to backwater from downstream debris causing ponded conditions.**12 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** SITES Wesconnet Blvd. 110th St. Cassat Ave. Blanding Blvd. 1,000

100

10

1.0

.10

0.01 MEASURED STREAMFLO W, IN CUBIC FEET PER SECOND 11 13

14 13 x x o

x x o x x FISHING CREEK SOUTH BRANCH BIG FISHWEIR CREEK

11 number of values EXPLANATION SCHEMATIC BOXPLOT

x x x

x x x o o o

o o o 75th percentile

median 25th percentile

lower outside lower detached upper detached upper outside

Note: Boxes with same colors are not significantly different.

**Figure 4.** Measured streamflow at data collection sites, Jac ksonville, Florida, 2000-2002 (site numbers refer to table 1).

13 number of values EXPLANATION SCHEMATIC BOXPLOT

x x x

x x x o o o

o o o 75th percentile

median 25th percentile

lower outside lower detached upper detached upper outside

SUBSET OF STREAMFLOW VALUES 13,580 1,004 13 13

x x x x x x x x x x x x x x x x x x x x

x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x o o o o

x x x x x x x x x x x x x x x x x x x x x x x x o o x o

x x

ORTEGA

RIVER 1965 - 2002 (PERIOD OF

RECORD) ORTEGA RIVER 2000 - 2002

(STUDY PERIOD) ORTEGA RIVER

(1) ORTEGA RIVER

(2) 10,000

1,000

100

10

1

0.01

0.1 DAILY MEAN STREAMFLO W, IN CUBIC FEET PER SECOND

(1) DAYS WHEN FISHING CREEK WAS MEASURED (2) DAYS WHEN SOUTH BRANCH FISHWEIR CREEK WAS MEASURED

**Figure 5.** Comparison of daily mean streamfl ow for Ortega River near Jacksonville for the period of record, January 1, 1965, to September 30, 2002; January 1, 2000, to September 30, 2002; and daily mean streamflows for days on which measurements were made at Fishing Creek at 110 th Street and South Branch Big Fishweir Creek at Blanding Boulevard.**Evaluation of Water Quality and Potential Effects of Septic Tank Effluent 13** 

### EVALUATION OF WATER QUALITY AND **POTENTIAL EFFECTS OF SEPTIC TANK EFFLUENT** 
The State of Florida developed a surface-water quality standards system, wh ich includes classification, criteria, anti-degradation policy, and special protection of certain waters (Florida Department of Environmental Protection, 2002). According to the State of Florida, the streams in this study are classified as Class III surface waters : used for recreation andpropagation and maintenance of a healthy, well-balanced population of fish and wildlife. Although the water-qualitydata generally represent the full range of hydrologic conditions previously described, a majority of the samples were taken at sites during periods of low flow, less than 2.5 ft 3 

### /s. Samples collected during low-flow periods represent surface water-quality conditions re sulting from ground-waterseepage (primarily septic effluent and upward movement of ground water from the surficial aquifer system). Samples collected duri ng storm events represent water-quality conditions asso ciated with surface runoff and shallow sub-surface flow of water to the stream. The surface runoff componen t of streamflow introduces variability in water- quality constituent concentrations observed and may dilute constituent concentrations due to the vo lume of water discharging to the stream. Constituent concentrations contributed to the stream water during storm events may overwhelm contributions from septic tanks, even though shallow sub-surface flow could “wash” constituents associated with septic tank effluent from the soil matrix. The Nationwide Urban Runoff Project (NURP) investigated variability in constituent concentrations for urbanized basins (Novotny and Olem, 1994, p. 491-493). The investigation involved collecting intensive storm-runoff water-quality samples from 28 cities across the United States. Analysis of the data from that study indicated that land-use effects areeclipsed by the storm-to-storm variability, and therefore, land use is of little use to predict urban runoff quality or to explain site-to-site differences. Because the sample sets collected fo r this study are relativelysmall and contain samples collected during storm-runoff events, it is reasonable to assume that differences in water quality between basins will be difficult to detect given the results of the NURP. If more samples had been collected and analyzed for low-flow eventsonly, then the results likely could determine differences in water quality of stream water between study basins based on land-use type (suburban high density versus suburban low density ). There were not enough samples collected for this study, however, to perform individual comparisons and analysis for sample sets representing the ground-water and storm-flow components of the streamflow. The water-quality standards system for Class III surface waters state that nut rients (total nitrogen and total phosphorus) shall be limited as needed to prevent violations of other standard s, that man-induced nutrient enrichment shall be considered degradation, and that nutrient concentrations of a water body shall not bealtered so as to cause an imbalance in the natural populations of aquatic flora and fauna (Florida Department of Environmental Protection, 2002). The U.S. Environmental Protection Agency (2000) lists nutrient criteria for rivers and streams in Ecoregion XII, which encompasses the study areas, as 0.90 millig rams per liter (mg/L) for total nitrogen and 0.04 mg/L for total phosphorus. Waste from warm blooded animals contributes a variety of intestinal bacteria that can be pathogenic to humans; body contact with water that contains pathogens can result in seve ral types of diseases in humans. The State of Florida fecal coliform bacteria standard for Class III surfacewaters is 800 colonies **Table 5.** Rainfall summary for selected sites in Jacksonville, Florida [Map number shown in figure 1]

**Map number**  **Site name and identification number**  **Annual rainfall total, inches**  **Average annual rainfall,**  **inches (period of record)**  **2000 2001 2002**
1 Jacksonville International Airport (084358) 39.77 49.14 54.74 52.9 (1931-2000)

2 Naval Air Station Jacksonville (722065) 40.64 51.57 46.96 47.5 (1945-1998)**14 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** 

### per 100 milliliters of water on any 1 day (Florida Department of Environmental Protection, 2002). Sources of bacteria can be from municipal wastewater discharges, leachate from domestic septic tanksystems, runoff or ground-water seepage from livestock producing areas (pasture and feedlots), areas where manure is applied as fertilizer, or from wildlife populations. Septic tanks are designed to reduce or eliminate most human healthor environmental threatsposed by pollutants in wastewater. Properly functioning septic tank systems result in retention and die-off of most pathogenic bacteria (U.S. Environmental Protection Agency, 2002b). Therefore, the presence ofthese organisms in surface water indicates fecal contamination and may also indicate the presence of pathogenic organisms. The most widely used indicator bacteria are total coliform, fecal coliform, enterococci and fecal streptococci groups, and Escherichia coli(U.S. Environmental Protection Agency, 2002a). The city of Jacksonville maintains a mo nitoring network throughout Duval County, and colle cts samples that are analyzed for fecal coliform bacteria (Deuerling and Cooner, 1995). To maintain uniformity in data collection practices throughout the County and to evaluate the water-quality conditions of the stream water, fecal coliform bacteria were sampled and analyzed as part of this study. Antibiotic use by animals and humans results in patterns of antibiotic resi stance in fecal coliform bacteria that reflect to some extent the exposure of fecal coliform bacteria to antibiotics (Harwood and others, 2000). The analysis used for this study is based on the assumption that fecal coliform bacteria from human sources will have a different resistance to selected antibiotics than th ose from different animal sources (Simpson and others, 2002). The antibiotic resistance patterns of fecal coliform bacteria were used to identify the sources of fecal coliform bacteria. Determination of the source of fecal material would indicate whether human waste (septic tank effluent) is impacting the quality of the stream water.



### Major Ions
Major ion concentrations can be used to compare surface-water and shallow ground-water characteristics and some can also be used as indicators of the effects of septic tank effluent. Pitt and others (1975) classified certain constituents as naturally occurring in ground water or associated with septic tank effluent,and summarized the chemical characteristics of shallow ground water in areas infl uenced by septic tanks in Dade County, Florida. Phelps (1994) summarized chemical characteristics of water from the surficial aquifer system in Duval Coun ty. A comparison of data from this study and those summarized by Pitt and others (1975) and Phelps (1994) is given in table 6.

**Table 6.** Summary of major ion constituents from surface-water sa mples for Fishing Creek and South Branch Big Fishweir Creek, Duval County, Florida, 2000-02; t he surficial aquifer system in Duval Count y,1970-89; and selected surficial aquifer wells in areas serviced by septic ta nks, Dade County, Florida, 1970-73 [All concentrations are dissolved and given in milligrams per liter, except where noted. μ S/cm, microsiemens per centimeter at 25 degrees Celsius; μ

g/L, micrograms per liter]

**Constituent Study basins**  **a ,**  **2000-02**

a Samples collected for this study. **Duval County b** 
**, 1970-89** 

b Phelps, 1994, table 3. **Septic tank influenced c**  **, 1970-73** 

c Pitt, 1975, tables 5 and 6. **Mean Range of values Mean Range of values Mean Range of values**
calcium 54 16

. - 84 120 51

. - 180 89 30

. - 120 chloride 28 5.4 - 72 16 3

. - 100 28 2.0 - 50 iron, μ g/L 231 24

. - 811 1,510 10

. - 12,000 1,910 .7 - 36,000 magnesium 7.3 2.1 - 12 4.2 1.6 - 13 3.2 .9 - 8.0 pH, standard units 7.1 6.2 - 7.7 5.8 3.8 - 8.1 7.7 d 6.8 - 8.5 potassium 3.3 1.7 - 5.1 .8 .4 - 1.0 3.1 .2 - 5.7 sodium 19 4.2 - 50 9.5 6.4 - 14 19 2.6 - 35 specific conductance, μ S/cm 409 63

. - 902 218 31

. - 960 541 182

. - 694 sulfate 40 3.9 - 83 12 .2 - 87 26 0.0 - 42

dMedian pH value.**Evaluation of Water Quality and Potential Effects of Septic Tank Effluent 15** 

### The specific conductance of water is a simple, useful measure of the pr esence of dissolved ions. Specific conductance values observed at study sites generally are comparable to specific conductance values observed in shallow ground water throughoutDuval County (table 6). Dissolved calcium and magnesium, dissolution products of native rock, also indicate the influence of shallow ground water on the water chemistry of stream water. Sodium, potassium, chloride, and sulfate are natu rally present in water, but also can be useful indicators of septic tank effluent(Pitt and others, 1975). The maximum dissolved potassium and sodium concentr ations exceed background data for Duval County and are similar to those observed in Dade County at sites influenced by septic tank effluent. Sodium is a conservative constituent that tends to remain in solution, and is introduced to septic tanksfrom grey and black water sources. Given the conservative nature of sodium, effluent from septic tanks likely will discharge elevated levels of sodium. Water samples for the Fishing Creek basin indicated sodiumconcentrations increased from upstream to downstream, and concentrations of sodium were greater in South Branch Big Fishweir Creek than in Fishing Creek (fig. 6). Increases insodium concentrations from upstream to downstre am in the Fishing Creek basin likely are due to the accumulation of septic tank effluent containing sodium as stream water moves downstream. The greater conc entration of sodium in the South Branch Big Fishweir Creek basin likely is the result of higher sep tic tank densities and leaky infrastructure or improperly functioning septic tank systems upstream from the study area. The fact that sodium concentrations did not increase from upstream to downstream in the South Branch Big Fishweir Creekbasin indicate that the stream may be at carrying capacity for constituents upstream from the South Branch Big Fishweir Creek at Cassat Avenue. Therefore, further addition of constituents within the study area will not affect constituent concentrations. Based on analysis of major ion samples, water-quality characteristics of the stream water in the study basins indicate influence from ground-water sources and septic tank activity. Trace constituent data generally were not useful in evaluating effects of septic tank effluent. Watersamples analyzed for boron and manganese had concentrations ranging from 20 to 99 micrograms per liter ( μ

g/L) and 2.1 to 12 μ g/L, respectively. Fifteen water samples from the Upper Floridan aquifer (Phelps, 2001) had boron concentrations ranging from 19 to 49 μ g/L and manganese concentrations ranging from 0.3 to 10 μg/L. The higher range of boron concentrations observed in the present study might be indicative of the influence of septic tanks in the study basins, because boron is a constituen t in household products.

x x

5787 FISHING CREEK SOUTH BRANCH BIG FISHWEIR CREEK

Note: Boxes with same colors are not significantly different. 30 number of values

EXPLANATION SCHEMATIC BOXPLOT

x x x

x x x o o o

o o o 75th percentile

median 25th percentile

lower outside lower detached upper detached upper outside

DISSOL VED SODIUM CONCENTRA TION, IN MILLIGRAMS PER LITER 60

50

40

30

20

10

0 Wesconnet Blvd. 110th St. Cassat Ave. Blanding Blvd. **Figure 6.** Concentrations of dissolved sodium at data collection sites, Jacksonville, Florida (site numbers refer to table 1).**16 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** 

### Nutrients
The basic forms of nitrogen in water are nitrite, nitrate, ammonia, and organic nitrogen. Greater than 50 percent of samples anal yzed for nitrite nitrogen had concentrations less than the laboratory reporting limit (0.01 mg/L); values ra nged from less than the laboratory reporting limit to 0.07 mg/L. Concentrations for nitrate nitrogen and ammonia nitrogen ranged from less than laboratory reporting limit (0.02 and0.01 mg/L, respectively) to 1.1 and 1.7 mg/L, respectively. Organic nitrogen concentrations were calculated by subtracting ammoni a nitrogen concentrations from the ammonia-plus-organ ic nitrogen concentrations. Stream-water samp les generally containedgreater amounts of organic nitrogen than other nitrogen species (fig. 7). Organic nitrogen concentrations ranged from 0.07 to 1.56 mg/L at study sites. Dissolved nitrite-plus-nitrate nitrogen were combined with total ammonia- plus-organic nitrogen to obtain an estimate of the total nitrogen concentration observed at study sites; total phosphorus was reported by the laboratory (table 7) . Total nitrogen concentrations given in this report are considered an underestimate of total nitrogen b ecause inorganic nitrogen sorbed to suspended sediment is not accounted for in the analysis of dissolved n itrite-plus-nitrate nitrogen. Water samples collected had estimated total nitrogen concentrations ranging from 0.33 to 2.86 mg/L and total phosphorus concentrations ranging from less than laboratory reporting limit (0.02 mg/L) to 0.64 mg/L. Concentrations of total nitrogen and total phosphorus in water sampled at study sites (Ecoregion XII) exceeded the U.S. Enviro nmental Protection Agency (2000) nutrient criteria for rivers and streams 49 and 96 percent of the time, respectively. The number of samples collected at sites was relatively small (less than 15), which makes statistical comparisons between sites of relatively limited use. Plots of total nitrogen (fig . 8) and total phosphorus (fig. 9) indicate that samples were not normally distributed at sites and had varied distributions. Visual comparison of the sample populations shows a difference from upstream to downstream and between Fishing Creek and South Branch Big Fishweir Creek basins. A comparison test was performed to determine whether sample sets of total nitrogen and total phosphorus have the same mean value. The statistical comparison indicated an upstream to downstream difference for total nitrogenin the South Branch Big Fishweir Creek basin (fig. 8) and a difference in mean concentration between the Fishing Creek and South Branch Big Fishweir Creek basins for total phosphorus (fig. 9).

ORGANIC NITRITE NITRATE AMMONIA NITROGEN CONCENTRA TION, IN MILLIGRAMS PER LITER

51 51 51

x o o x x x x o o 51

x o 2

1.5

1

0.5

0 13 number of values EXPLANATION SCHEMATIC BOXPLOT

x x x

x x x o o o

o o o 75th percentile

median 25th percentile

lower outside lower detached upper detached upper outside

**Figure 7.** Concentrations of nitrogen species at datacollection sites, Jacksonville, Florida.**Evaluation of Water Quality and Potential Effects of Septic Tank Effluent 17 Table 7.**  Summary of nitrogen and phosphorus concentrations for surfac e-water samples, Jacksonville, Florida [USGS, U.S. Geological Survey; constituent concentration values are in milligrams per liter; <, less than. Map numbers shown in figures 2 and 3]

**Map number**  **Site name and**  **USGS identification number Number**  **of samples**  **Total nitrogen Total phosphorus**

**Mean Median Range**  **of values**  **Mean Median Range**  **of values** 

4 Fishing Creek at Wesconnet Boulevard (02246435) 11 1.00 .82 .55 - 1.64 .08 .07 .04 - .19

5 Fishing Creek at 110 thStreet (0226437) 13 1.00 1.05 .53 - 1.73 .07 .06 <.02 - .18

6 South Branch Big Fishweir Creek at Casssat Avenue (02246465) 14 .86 .69 .33 - 2.86 .11 .08 .07 - .64

7 South Branch Big Fishweir Creek at Blanding Boulevard (02246467) 13 1.26 1.30 .45 - 2.00 .13 .12 .08 - .53

11 13 14 o

13 FISHING CREEK SOUTH BRANCH BIG FISHWEIR CREEK
TOTAL NITR OGEN CONCENTRA TION, IN MILLIGRAMS PER LITER 3.5

3.0

2.0

1.5

0.5

0.0 1.0 2.5

SITES Wesconnet Blvd. 110th St. Cassat Ave. Blanding Blvd. 11 number of values EXPLANATION SCHEMATIC BOXPLOT

x x x

x x x o o o

o o o 75th percentile

median 25th percentile

lower outside lower detached upper detached upper outside

Note: Boxes with same colors are not significantly different.

**Figure 8.** Concentrations of total nitrogen at data collection sites, Jacksonville, Florida (site names refer to table 1).**18 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** 

### The potential effects of septic tanks on streamwater quality can be evaluated by comparing constituent contributions to septic tanks, removal efficiencies, and constituent concentratio ns observed in streamwater samples. Wastewater di scharges to septic tanks were studied by the U.S. Environmental Protection Agency (U.S. Environmental Protection Agency, 2002b) and the State of Florida (Florida Executive Office of the Governor, 1999). These studies reported characterizations of septic tank effluent, and gave the average daily constituent co ncentrations contributed directly to septic tanks fo r total nitrogen and total phosphorus as ranging from 26 to 75 and 6 to 12 mg/L, respectively (U.S. Environmental Protection Agency, 2002b). Sikora and Corey (1976) list the potential removal efficiency of sep tic tank systems for total nitrogen and total phosphorus as 10 to 40 percent and 85 to 95 percent, respectively. These removal efficiencies are based on observations of ground water exiting the septic tank drain field. Based on constituent contributions to septictanks, removal efficiencies, and constituent concentrations observed in stream-water samples, removal efficiency for both total nitrogenand total phosphorus are greater than 90 percent. Water samples collected for x

x x o

11 13 14

13 11 number of values EXPLANATION SCHEMATIC BOXPLOT

x x x

x x x o o o

o o o 75th percentile

median 25th percentile

lower outside lower detached upper detached upper outside

Note: Boxes with same colors are not significantly different. TOTAL PHOSPHOR US CONCENTRA TION, IN MILLIGRAMS PER LITER 0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0 FISHING CREEK SOUTH BRANCH BIG FISHWEIR CREEK

SITES Wesconnet Blvd. 110th St. Cassat Ave. Blanding Blvd.

**Figure 9.** Concentrations of total phosphorus at data collection sites, Jacksonville, Florida (site names refer to table 1).



### this study were taken at a great distance (hundreds of feet) from individual septic tanks. These samples reflect potential input from other sources, such as fertilizer application, and changes in nitrogen and phosphorus as a result of adsorption and microbially mediated transformation. Based on calculations of removal efficiency, septic tank systems in the study basins were functioning properly at times and for hydrologic conditions when samples were collected. However, the hydrology of the study areas (shallow surficial aquifer system, fine -grained upland soils, and little topographic relief) and construction methods of individual septic systems affect the operation and efficiency of septic tank systems in the study areas, and therefore, affect stream-water quality.



### Wastewater Constituents
Chemical analysis of stream-water samples for compounds commonly found in wastewater was used to evaluate the impact of sanitary sewer or septic tank outflow on the water quality of study streams. Organic wastewater compounds detected above the minimum laboratory-reporting level are listed in table 8.**Evaluation of Water Quality and Potential Effects of Septic Tank Effluent 19** 

### Compounds detected were detergents, antioxidantsand flame retardants, manufactured polycarbonate resins, industrial solvents, an d mosquito repellent. The most commonly detected compound was para-nonylphenol, which is a detergent metabolite; it was detected in both the Fish ing Creek and South BranchBig Fishweir Creek basins. The likely source of paranonylphenol is wastewater from washing machines and dishwashing detergents di scharged to septic tanks.Another compound detected in both basins was N,Ndiethyl-meta-toluamide (Deet). The source of this compound likely is wastewater produced by residentsbathing or washing clothing after using personal insecticides containing Deet or runoff of overspray. Another compound detected in the Fishing Creek basin was bisphenol-A; this compound is used primarily to make polycarbonate plastic and epoxy resins. Samples for the South Branch Big Fishweir Creek basin had a greater number of compounds (table 8) detected than did samples from the Fishing Creek basin. The South Branch Big Fishweir Creek basin contains some small business development, which likely contributed to detections of compounds such as isophorone, an industrial solvent. Most of the compounds detected are commonly associated with grey water discharges to septic tanks in the study areas; therefore, their presence indicates that the Fishing Creek and South Branch Big Fishweir Creek basins are influenced by wastewater from septic tanks.



### Bacteria

Fecal coliform bacteria concentrations were measured on a monthly basis; of 115 samples, 63 percent exceeded the State of Florida fecal coliform bacteria standard for Class III surface waters of 800 colonies per 100 milliliters of water on any 1 day. The results of individual water samples collected for fecal coliform bacteria analysis are given in appendix 3. Fecal coliform b acteria in water samples were reported as most prob able number per 100 milliliters (mpn/100mL) of sample and ranged from less than 20 mpn/100mL at Fishing Creek at Wesconnet Boulevard to equal to or greater than 160,000 mpn/100mL at South Branch Big Fishweir Creek at Blanding Boulevard (table 9). The median and geometric mean indicate that colony concentrations increase from upstream to downstre am for the Fishing Creek basin, and that the South Branch Big Fishweir Creek basin has higher colony concentrations than those for the Fishing Creek basin. **Table 8.** Concentrations of organic wastewatercompounds above the minimum laborat ory-reporting level, Jacksonville, Florida [d, nonionic detergent metabolite; a, manuf actured polycarbonate resins, antioxidant, flame retardant; i, insecticide, urban us es, mosquito repellent; p, plasticizer, flame retardant; c, beverages, diuretic; s, solven t for lacquer, plastic, oil, silicon, resin; m, cigarettes, co ugh drops, liniment, mouthwash; e, compound was detected but concentrations with low recovery, high variable recovery, unstable instrument response, or from tec hnical mixture are not quantified; μ g/L, micrograms per liter. Map numbers shown in figures 2 and 3 ]

**Map number**  **Site name Sample**  **date Constituent name**  **Possible compound** 

**uses or sources**  **a Concen**  **tration (**  μ

**g/L)**
4 Fishing Creek at Wesconnett Boulevard 8/21/2001 para-Nonylphenol (total) d e 4 Fishing Creek at Wesconnett Bo ulevard 2/26/2002 Bisphenol A a 1.1 4 Fishing Creek at Wesconnett Boulevard 2/26/2002 para-Nonylphenol (total) d e 5 Fishing Creek at 110th Street 7/11/2000 N,N -diethyl-meta-toluamide (Deet) i 1.32 5 Fishing Creek at 110th Stre et 2/26/2002 Bisphenol A a 2.7 6 South Branch Big Fishweir Creek at CassatAvenue 7/11/2000 tri(2-chloroethyl)phosphate p .88 6 South Branch Big Fishweir Creek at Cassat Avenue 8/21/2001 Caffeine c 2 6 South Branch Big Fishweir Creek at Cassat Avenue 8/21/2001 Isophorone s 12 6 South Branch Big Fishweir Creek at Cassat Avenue 8/21/2001 Menthol m .85 6 South Branch Big Fishweir Creek at Cassat Av enue 8/21/2001 N,N-diethyl-m eta-toluamide (Deet) i .81 6 South Branch Big Fishweir Creek at Cass at Avenue 8/21/2001 para-Nonylphenol (total) d e 7 South Branch Big Fishweir Creek at Blanding Boulevard 8/22/2001 Isophorone s 3.1 7 South Branch Big Fishweir Creek at Blandi ng Boulevard 8/22/2001 para-Nonylphenol (total) d e 7 South Branch Big Fishweir Creek at Blandi ng Boulevard 2/26/2002 para-Nonylphenol (total) d e

aZaugg, 2002, table 1.**20 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** 

### Fecal coliform bacteria concentrations were significantly higher in the South Branch Big Fishweir Creek basin than in the Fishing Creek basin (fig. 10). This likely is the result of the higher density of septic tanks per acre in the South Branch Big Fishweir Creek basin. Fecal coliform bacteria concentrations also were significantly greater at the downstream site on Fishing Creek compared to the upstream site. Increases in bacteria concentrations from upstream to downstream in the Fishing Creek basin likely are due to the accumulation of septic tank effluent as stream water moves downstream. There was no significant difference in the fecal coliform bacteria concentrations between the two South Bran ch Big Fishweir Creek sites. This likely is due to the varaiation in housing and septic tank density in th e Fishing Creek basin and higher colony concentrati ons observed in the South Branch Big Fishweir Creek basin, which make it more difficult to observe significant differences in the sample population mean give n a similar increase in colony concentrations from upstream to downstream. The lack of significant difference between upstream and downstream bacteria concentrations may also be an indication that the South Branch Big Fishweir Creek basin is at carrying capacity and addition ofseptic tank effluent to the stream will not affect bacteria populations. Overall, fecal coliform bacteria concentrations exceeded the State of Florida Class III surface-water standards and reflect the impact of septic tank effluent on the quality of stream water. Water samples analyzed for antibiotic resistancepatterns of fecal coliform bacteria were used to evaluate the potential impact of human activity on the quality of stream water. A total of 16 samples was collected, and fecal coliform bacteria isolates were classified into five source catagories for each sample; chicken, cow, dog, human, and wildlife. Fecal coliform bacteria were detected and classified at significant levels (greater than 20 percent) for 23 of the 80 potential classificatio ns (1 chicken, 3 dog, 14 human, and 5 wildlife). Individual sample results (app. 4) were combined for each of the study sites to obtain an average likelihood of potential sources for the entire study period (table 10). Significant sources of fecal coliform bacteria isolates over the study period as determined by the antibiotic resistance analysis were wild animals and humans. A majority of the fecal coliform bacteria were classified to be from human sources; these were detected at a significant level for all study sites in both the Fishing Creek and South Branch Big Fishweir Creek basins. Fecal coliform bacteria classified as from wild animals were detected at significant levels at Fishing Creek at 110 th 

### Street. Detections of fecal coliform bacteria isolates from wild animal sources for Fishing Creek at 110 th 

### Street occurred during and following installation of the sanitary sewer system in frastructure in the basin. Samples collected at this site indicated a change in known source classification from human to a mix of human and wild animal and later dog and wild animal over the study period (app. 4). The change in classification of known sources likely occurred due to drainage changes made in the stream and other parts of the basin during construction and connection of residences to the sanitary sewer system following its completion in November 2002 (Dana Morton, city of Jacksonville, Division of Air and Water Quality, oral commun., 2003). Results of the fecal coliform bacteria antibiotic resistance analysis indicate that movement of septic tank effluent through the soil matrix and discharged to the stream contributes to fecal coliform bacteria popul ations observed in the stream water. Because the primary source of fecal coliform bacteria is from hum an sources, most likely septic tank effluent, management of human sources may substationally improve microbiological water quality in both the Fishin g Creek and South Branch Big Fishweir Creek basins. **Table 9.** Fecal coliform bacteria summary for surfac e-water samples, Ja cksonville, Florida [USGS, U.S. Geological Survey; <, less than; fecal coliform bact eria values are reported as mo st probable numb er per 100 millil iters. Map numbers shown in figures 2 and 3]
**Map number**  **Site name and USGS identification number**  **Number of**  **samples Maximum Minimum Median**  **Geometric**
**mean**
4 Fishing Creek at Wesconnet Boulevard (02246435) 25 50,000 <20 70 138

5 Fishing Creek at 110 thStreet (0226437) 28 50,000 20 900 926

6 South Branch Big FishweirCreek at Casssat Avenue (02246465) 31 160,000 40 5,000 3,720

7 South Branch Big Fishweir Creek at Blanding Boulevard (02246467) 31 ≥ 160,000 800 6,000 7,040**Evaluation of Water Quality and Potential Effects of Septic Tank Effluent 21** 24 27 30 30

x x

x FECAL COLIFORM BA CTERIA, MOST PR OBABLE NUMBER PER 100 MILLILITERS 1
, 000
, 000

100,000

10,000

1,000

100

10 FISHING CREEK SOUTH BRANCH BIG FISHWEIR CREEK

SITES Wesconnet Blvd. 110th St. Cassat Ave. Blanding Blvd. Note: Boxes with same colors are not significantly different. 30 number of values

EXPLANATION SCHEMATIC BOXPLOT

x x x

x x x o o o

o o o 75th percentile

median 25th percentile

lower outside lower detached upper detached upper outside

**Figure 10.** Concentrations of fecal coliform bacteria at data collection sites, Jacksonville, Florida (site names refer to table 1).

**Table 10.** Summary of discriminant analysis of antibiotic resistanc e patterns used to classify fecal coliform bacteria from known sources into source categories fo r surface-water samples, Jacksonville, Florida [USGS, U.S. Geological Survey; map numbers shown in figures 2 and 3. Percentages may not equal 100 percent due to rounding]

**Map number**  **Site name and USGS identification number**  **Classifications of fecal coliform bacteria isolates Total**  **count (percent)**  **Chicken**

**count (percent)**  **Cow count**  **(percent) Dog**  **count (percent)**  **Human count**  **(percent) Wild**  **count (percent)** 
4 Fishing Creek at Wesconnet Boulevard (02246435) 6 (3.2) 1 (.5) 17 (9.1) 126 (67.4) 37 (19.8) 187 (100)

5 Fishing Creek at 110 thStreet (0226437) 3 (2.3) 4 (3.1) 18 (13.7) 62 (47.3) 44 (33.6) 131 (100)

6 South Branch Big Fishweir Creek at Casssat Avenue (02246465) 12 (6.7) 1 (.6) 10 (5.6) 145 (80.6) 12 (6.7) 180 (100)

7 South Branch Big Fishweir Creek at Blanding Boulevard (02246467) 11 (5.7) 0 (.0) 34 (17.6) 131 (67.9) 17 (8.8) 193 (100)**22 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** 

### SUMMARY

Tributary streamflow to the St. Johns River in Duval County is thought to beaffected by septic tank leachate from residential ar eas adjacent to these tributaries. Water managers and the city of Jacksonville have committed to infrastructure improvements as part of a management plan to address the impairment of tributary water quality. Major ion, nutrient, and fecalcoliform concentrations, detection of wastewater compounds, and tracking of bacterial sources were used to document septic tank influe nces on the water qualityof selected tributaries in order to provide data to evaluate the effects of future remedial activities in selected tributaries. The tributaries of Fishing Creek and South Big Fishweir Creek were selected because they coincide with subdivisions identified as high-priority locations for septic tank phase-out projects: the Pernecia and Murray Hill B subdivisions, re spectively. The data collection networks consisted of two sites in each study basin located at points upstream and downstream fromareas where septic tanks are to be replaced by a sanitary sewer system. These s ites provided information on the hydrologic and water-quality characteristics of the study basins over the study period, April 1999 to September 2002. The Fishing Creek basin is west of the St. Johns River and joins the Ortega River south (upstream) of its confluence withthe Cedar River. The Big Fishweir Creek basin is west of the St. Johns River and joins the Ortega River at its confluen ce with the St. Johns River. Both creeks are relatively narrow, 25 feet or less in width, with definitive banks that are 3-6 feet high, especially in the lower reaches of the basin. The Pernecia subdivision covers an area of about 193 acres, of which 156 acres drain to Fishing Creek; the Murray Hill B subdivisio n is about 465 acres, of which 154 acres drain to South Branch Big Fishweir Creek. Population, housing (number of residences), and septic tank densities for the Fishing Creek and South Branch Big Fishweir Creek basins are 2.7 and 6.0 people per acre, 1.3 and 2.3 houses per acre, and 1.3 and 2.7 septic tanks per acre, respectively. Measured streamflows ranged from 107 cubic feet per second (ft 3 

### /s) at Fishing Creek at 110th Street to 0.02 ft 3 

### /s at the South Branch Big Fishweir Creek at Cassat Avenue. Streamflows for Fishing Creek tend to be greater than those for South Branch Big Fishweir Creek, and streamflow increases from upstream to downstream in both basins. Based on calculations from periodic measurements of streamflow, the runoff per unit area is greater in the Fishing Creek basin than in the South Branch Big Fishweir Creek basin. Water samples analyzed for major ions and nutrients were collected in conjunction with discharge measurements. A majority of the samples collected were during periods of low flow, less than 2.5 ft 3 

### /s, and generally represent base-flow conditions. Analysisof major ion samples indicates influence from groundwater sources and septic tank activity. The maximum levels for dissolved potassium and sodium exceed those elsewhere in Duval Co unty and are similar to those in Dade County at site s influenced by septic tank effluent. Stream-water samples generally containedgreater amounts of organic nitrogen than other nitrogen species, and concentrations ranged from 0.07 to 1.56 milligrams per liter (m g/l). Concentrations of total nitrogen ranged from 0. 33 to 2.86 mg/L, and concentrations for total phosphorus ranged from less than laboratory reporting limit (0.02 mg/l) to 0.64 mg/l. Concentrations of total nitrogen and total phosphorussampled at study sites exceeded the U.S. Environmental Protection Agency Ecoregion XII nutrient criteria for rivers and streams 49 and 96 percent of the time, respectively. Wastewater compounds detected at study sites were categorized as detergents, antioxidants and flameretardants, manufactured polycarbonate resins, industrial solvents, and mosquito repellent. The SouthBranch Big Fishweir Creek basin had a greater number of compounds detected than the Fishing Creek basin. The most common compound detected was para-nonylphenol, which is a breakdown product of detergent. It was detected in both the Fishing Creek and South Branch Big Fishweir Creek study basins. Results of wastewater sampling indicate the presence of septic tank leachate in stream water. Fecal coliform bacteria concentrations were measured on a monthly basis; of 115 samples, 63 percent exceeded the State of Florida fecal coliform bacteria standard for Class III surface waters of 800 colonies per 100 milliliters of water on any 1 day. Fecal coliform bacteria concentrations ranged from less than than 20 most pr obable number per 100 milliliters (mpn/100mL) of sampleat Fishing Creek at Wesconnet Boulevard to equal to or greater than**References 23** 

### 160,000 mpn/100mL at South Branch Big Fishweir Creek at Blanding Boulevard. Fecal coliform bacteria concentrations were significantly higher in the South Branch Big Fishweir Creek basin than in the Fishing Creek basin during the stud y. Antibiotic resistance patterns of fecal coliform bacteria were used to identify the sources of fecal coliform bacteria. Significant sources of fecal coliform bacteria included wild animals, dogs, and hu mans. A majority of the fecal coliform bacteria were classified to be from human sources. Because the primary source of fecal coliform bacteria is from human sources, most likely septic tank effluent, management of human sources may substationally improve microbiological water quality in both the Fishing Creek and South Branch Big Fishweir Creek basins.



### REFERENCES

Anderson, Warren, 1972, Surface water in Duval and Nassua Counties, Florida: U. S. Geological Survey Open-File Report 72-007, 65 p. Causey, L.V., 1975, Depth to water table, recharge areas, drainage basins, and relief of Duval County, Florida: U. S. Geological Survey Wate r-Resources Investigations Open-File Report 52-75, 4 sheets. City of Jacksonville, 2000, Be tter Jacksonville plan, project and funding, septic tank remediation [cited October 9, 2002] http://betterjax.com, and http:// groundworks.jea.com/projects/schedule_table.asp. Clesceri, Lenore S., Greenberg, Arnold E., and Eaton, Andrew D., eds., 1998, Standard methods for the examination of water and wastewater (20th ed.): American Public Health A ssociation, American Water Works Association, and Water Environment Federation, 1,220 p. Cooke, C.W., 1945, Geology of Florida: Florida Geological Survey Bulletin 29, 339 p. Deuerling, Betsy, and Cooner, Al, 1995, Water quality report 1990-1991, tributaries to the Saint Johns River, Duval County, Florida: Water Quality Division Regulatory and Environmental Services Department, City of Jacksonville, Florida, 178 p. Fishman, M.J., and Friedman, L.C., eds., 1989, Methods for determination of inorganic substances in water and fluvial sediments: U.S. Geological Survey Techniques of Water-Resources Investigations, book 5, chap. A1, 545 p. Florida Department of Environmental Protection, 2002, Florida administrative code chapter 62-302: surface water quality standards, p. 418-450 [cited February 3, 2002] http://election.dos.state.fl.us/fac/index.shtml. Florida Executive Office of the Governor, 1999, Onsite sewage treatment and disposal in Florida: Draft background paper for the Governor’s study of onsite sewage treatment and disposal systems, prepared by Department of Community Affairs, Department of Environmental Protection, Department of Health [cited March 7, 2003] http://consensus.fsu.edu/OSTDS/ ostds_background.html. Harwood, Valerie J., Whitlock, John, and Withington, Victoria, 2000, Classificati on of antibiotic resistance patterns of indicator bacteria by discriminant analysis—Use in predicting the source of fecal contamination in subtropical waters: Applied and Environmental Microbiology, v. 66, no. 9, p. 3698- 3704. Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods in water resources: Studies in Environmental Science 49, New York, Elsevier Science Publishers, 529 p. Jacksonville Electric Authority, 2002, JEA 2002 Annual report, fiscal year highlights [cited March 3, 2003] http://www.jea.com/about/news/bond_investor.asp. Novotny, V. and Olem, H., 1994, Water quality—Prevention, identification, and management of diffuse pollution: Van Nostrand Reinhold, New York, 1054 p. Phelps, G.G., 1994, Water resources of Duval County, Florida: U.S. Geological Survey Water-Resources Investigations Report 93-4130, 78 p. ———2001, Geochemistry and origins of mineralized waters in the Floridan aquifer system, northeastern Florida: U.S. Geological Survey Water-Resources Investigations Report 01-4112, 64 p. Pitt, W.A.J., Jr., Mattraw, H.C., Jr., and Klein, Howard, 1975, Ground-water quality in selected areas serviced by septic tanks, Dade County, Florida: U.S. Geological Survey Open-File Report 75-607, 82 p. Rantz, S.E., and others, 1982, Measurements and computation of streamflow: Volume 1. Measurement of stage and discharge; and Volume 2. Computation of discharge, U.S. Geological Survey Water-Supply Paper 2175, 631 p. Sikora, L.J., and Corey, R.B., 1976, Fate of nitrogen and phosphorus in soils under septic tank waste disposal fields: Transactions of American Society of Agricultural Engineers, v. 19, p. 866. Simpson, J.M., Santo Domingo, J.W., Reasoner, D.J., 2002, Microbial source tracking: State of the science—Environ-mental Science and Technology, v. 36, no. 24, p. 5279-5288. U.S. Department of Agri culture, Natural Resource Conservation Service, 1998, Soil survey of City of Jacksonville, Duval County, Florida, 218 p.**24 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida** U.S. Environmental Protection Agency, 2000, Office of Water, ambient water quality criteria recommendations, information supporting the development of state and tribal nutrient criteria: Rivers and streams in nutrient Ecoregion XII: U.S. Environmental Protection Agency EPA 822-B-00-021 December 2000 [cited Oc tober 18, 2002] http:// www.epa.gov/waterscience/criteria/nutrient/ ecoregions/rivers/rivers_12.pdf. ———2002a, Office of Water, Implementation guidance for ambient water quality criteria for bacteria: U.S. Environmental Protection Agency EPA-823-B-02-003 June 2002 [cited September 2, 2003] http:// www.epa.gov/ost/standard s/bacteria/bacteria.pdf. ———2002b, Office of Water, Office of Research and Development, Onsite wast ewater treatment systems manual: U.S. Environmental Protection Agency EPA/ 625/R-00/008 February 2002 [cited February 2, 2003] http://www.epa.gov/ORD/NRMRL/Pubs/625R00008/ 625R00008.htm.———2003, Inductively coupled plasma—Atomic emission spectrometric method for trace element analysisof water and waste method 200.7: U.S. Code of Federal Regulations, Title 40, Part 136, Appendix C [cited April 25, 2003] http://www .access.gpo.gov/nara/cfr/ cfrhtml_00/Title_40/40cfr136_00.html. U.S. Geological Survey, 2003, Water resources data, Florida, water year 2002, v. 1A, northeast Florida surface water: U.S. Geological Survey Water-Data Report, FL-02-1A, 401 p. Wiggins, Bruce A., Andrews, R.W., Conway, R.A., Corr, C.L., Dobratz, E.J., Dougherty, D.P., Eppard, J.R., Knupp, S.R., Limjoco, M.C., Mettenburg, J.M., Rinehardt, J.M., Sonsino, J., Torrijos, R.L., and Zimmerman, M.E., 2003, Use of antibiotic resistance analysis for representativeness testing of multiwatershed libraries: Applied and Environmental Microbiology, v. 69, no. 6, p. 3399-3405. Wilde, F.D., and others, eds., 1998, National field manual for the collection of water-quality data: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9 [variously paged]. Zaugg, S.D., Smith, S.G., Schoeder, M.P., Barber, L.B., and Burkhardt, M.R., 2002, Met hods of analysis by the U.S. Geological Survey National Water Quality Laboratory—Determination of wastewater compounds by polystyrene-divinylbenzene solid-phase extraction and capillary-column gas chromatography/massspectrometry: U.S. Geological Survey WaterResources Investigations Report 01-4186, 37 p.**Appendix 1 25 Appendix 1.**  Constituents analyzed as part of major ion and nutrient sampling [mg/L; milligrams per liter]

**Constituent name Method**  **reporting limit (mg/L)** 

acid neutrali zing capacity 1

boron .002

calcium .02

chloride .1

fluoride .1

iron .002
magnesium .03
manganese .001
nitrogen, ammonia, dissolved .01
nitrogen, ammonia plus organic nitrogen,

total .2

nitrogen, nitrite, dissolved .01
nitrogen, nitrite plus nitrate, dissolved .02
pH .1 a

a standard units phosphorus, dissolved .02
phosphorus, total .02
phosphorus, phosphate, ortho, dissolved .018
potassium .1

silica .01

sodium .1
specific conductance 1. b

b microSiemens per centimeter at 25 degrees Celsius sulfate .2**26 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida Appendix 2.**  Constituents analyzed as part of the U.S. Geologic al Survey National Water-Quality Laboratory organic wastewater sample series [mg/L, micrograms per liter]

**Constituent name Method**  **reporting limit (**  μ

**g/L) Constituent name**  **Method reporting limit**  **(** μ

**g/L)**
1-Methylnaphthalene .5 Fluoranthene .5 1,4-Dichlorobenzene .5 Hex adydrohexamethylcyclopentabenzopyran (HHCB) .5

2,6-Dimethylnaphthalene .5 Indole .5 2-Methylnaphthalene .5 Isoborneol .5 3-beta-Coprostanol 2 Isophorone .5 3-Methyl-1(H)-indole (Skatole) 1 Isopropylbenzene .5 3-tert-Butyl-4-hydroxy anisole

(BHA) 5 Isoquinoline .5

4-Cumylphenol 1 Menthol .5 4-n-Octylphenol 1 Metalaxyl .5 4-tert-Octylphenol 1 Methyl salicylate .5 5-Methyl-1H-benzotri azole 2 Metolachlor .5 Acetophenone .5 N,N-diethyl-meta-toluamide (DEET) .5

Acetyl hexamethyl tetrahydronaphthalene (AHTN) .5 Naphthalene .5

Anthracene .5 Nonylphenol, diethoxy- (total) 5 Anthraquinone .5 Octylphenol, diethoxy- 1 Benzo[a]pyrene .5 Octy lphenol, monoethoxy- 1 Benzophenone .5 p-Cresol 1 beta-Sitosterol 2 para-Nonylphenol (total) 5 beta-Stigmastanol 2 Pentachlorophenol 2 Bisphenol A 1 Phenanthrene .5
Bromacil .5 Phenol .5
Bromoform .5 Prometon .5 Caffeine .5 Pyrene .5 Camphor .5 Tetrachloroethylene .5 Carbaryl 1 Tri(2-chloroethyl)phosphate .5 Carbazole .5 Tris(dichlo risopropyl)phosphate .5 Cholesterol 2 Tributyl phosphate .5 Chlorpyrifos .5 Triclosan 1 Cotinine 1 Triethyl citrate (ethyl citrate) .5
d-Limonene .5 Tri phenyl phosphate .5 Diazinon .5 Tri(2-butoxyethyl)phosphate .5
Dichlorvos 1**Appendix 3 27 Appendix 3.**  Fecal coliform bacteria counts for surface-water samples
[Fecal coliform bacteria values are reportedas most probable number per 100 milliliters ; <, less than; >, greater than or equa l]

**Fishing Creek at Wesconnet Boulevard**  **(02246435) Fishing Creek at**  **110th Street (02246437)**  **South Branch Big Fishweir Creek at** 

**Cassat Avenue**

**(02246465) South Branch Big**  **Fishweir Creek at Blanding Boulevard**  **(02246467)**

**Date Bacteria**  **estimate Date**  **Bacteria estimate**  **Date Bacteria**  **estimate Date**  **Bacteria estimate** 
2/7/2000 270 2/7/2000 1,700 2/8/2000 3,000 2/8/2000 17,000 3/8/2000 70 3/8/2000 800 3/8/2000 1,700 3/8/2000 7,000
4/18/2000 20 4/18/2000 110 4/ 18/2000 5,000 4/18/2000 5,000 5/23/2000 <20 5/23/2000 3,000 5/23/2000 5,000 5/23/2000 1,700
8/8/2000 20 7/11/2000 800 6/12/2000 160,000 6/12/2000 160,000 9/5/2000 70 8/8/2000 20 7/11/2000 11,000 7/11/2000 30,000 9/18/2000 700 9/5/2000 1,400 8/8/2000 11,000 8/8/2000 16,000 10/10/2000 20 9/18/2000 140 9/6/2000 50,000 9/6/2000 90,000
11/28/2000 500 10/10/2000 330 10/ 10/2000 5,000 10/10/2000 50,000 12/12/2000 40 11/28/2000 270 11/28/2000 5,000 11/28/2000 > 16,000
1/16/2001 500 12/12/2000 170 12/ 13/2000 9,000 12/13/2000 9,000 2/6/2001 300 1/16/2001 1,300 1/ 16/2001 5,000 1/16/2001 3,000 3/13/2001 500 2/6/2001 330 2/7/2001 3,000 2/7/2001 1,700 4/10/2001 40 3/13/2001 3,000 3/ 13/2001 1,100 3/13/2001 2,800 7/9/2001 500 4/10/2001 300 4/10/2001 1,300 4/10/2001 800 9/10/2001 110 6/6/2001 1,100 5/15/2001 40 5/15/2001 800 10/15/2001 220 7/9/2001 700 6/6/2001 1,300 6/6/2001 1,700 11/6/2001 40 9/10/2001 1,300 7/9/2001 3,500 7/9/2001 > 16,000 12/10/2001 50,000 10/15/2001 2,200 9/10/2001 2,200 8/22/2001 2,400 1/15/2002 9,000 11/6/2001 5, 000 10/15/2001 700 9/10/2001 9,000 2/26/2002 40 12/10/2001 50,000 11/7/2001 1,100 10/15/2001 2,200 3/26/2002 20 1/15/2002 17,000 12/ 10/2001 30,000 11/7/2001 1,700 4/9/2002 40 2/26/2002 1,700 1/ 15/2002 17,000 12/10/2001 90,000
7/9/2002 40 3/26/2002 700 2/26/2002 800 1/15/2002 22,000 9/25/2002 1,400 4/9/2002 3,000 3/26/2002 7,000 2/26/2002 800 7/9/2002 900 4/9/2002 500 3/26/2002 2,200 8/12/2002 500 5/7/2002 5,000 4/9/2002 2,400 9/25/2002 2,800 6/18/2002 16,000 5/7/2002 2,200 7/9/2002 1,300 6/18/2002 9,000 8/12/2002 5,000 7/9/2002 > 160,000 9/25/2002 2,200 9/25/2002 50,000**28 Evaluation of Water Quality for Two St. Johns River Tributaries Receiving Septic Tank Effluent, Duval County, Florida Appendix 4.**  Discriminant analysis of antibiotic resistance patterns used to classify fecal coliform bacteria from known sources into source categories for surface-water samples [USGS, U.S. Geological Survey]

**Site name and USGS identification number**  **Categories Total**  **count (percent)**  **Chicken count (percent)**  **Cow count (percent)**  **Dog count (percent)**  **Human count (percent)**  **Wild count (percent)**  September 2001 sampling Fishing Creek at Wesconnet Boulevard

(02246435) 3 (6) 1 (2) 5 (10) 40 (80) 1 (2) 50 (100)

Fishing Creek at 110 thStreet

(0226437) 1 (16.7) 0 (0) 0 (0) 5 (83.3) 0 (0) 6 (100)

South Branch Big Fishweir Creek

at Casssat Avenue (02246465) 0 (0) 1 (2.7) 1 (2.7) 35 (94.6) 0 (0) 37 (100)

South Branch Big Fishweir Creek

at Blanding Boulevard (02246467) 0 (0) 0 (0) 0 (0) 51 (100) 0 (0) 51 (100)

Total 7 (3.7) 2 (1) 14 (7.3) 167 (87) 2 (1.04) 192 (100) December 2001 sampling Fishing Creek at Wesconnet Boulevard

(02246435) 1 (2.1) 0 (0) 1 (2.1) 46 (95.8) 0 (0) 48 (100)

Fishing Creek at 110 thStreet

(0226437) 2 (4.2) 4 (8.3) 2 (4.2) 40 (83.3) 0 (0) 48 (100)

South Branch Big Fishweir Creek

at Casssat Avenue (02246465) 4 (8.3) 0 (0) 6 (12.5) 38 (79.2) 0 (0) 48 (100)

South Branch Big Fishweir Creek

at Blanding Boulevard (02246467) 1 (2.1) 0 (0) 6 (12.5) 41 (85.4) 0 (0) 48 (100)

Total 8 (4.2) 4 (2.1) 15 (7.8) 165 (85.9) 0 (0) 192 (100) September 2002 sampling Fishing Creek at Wesconnet Boulevard

(02246435) 1 (2.1) 0 (0) 0 (0) 37 (78.7) 9 (19.2) 47 (100)

Fishing Creek at 110 thStreet

(0226437) 0 (0) 0 (0) 2 (6.7) 15 (50) 13 (43.3) 30 (100)

South Branch Big Fishweir Creek

at Casssat Avenue (02246465) 8 (17) 0 (0) 0 (0) 38 (80.8) 1 (2.1) 47 (100)

South Branch Big Fishweir Creek

at Blanding Boulevard (02246467) 10 (21.3) 0 (0) 21 (44.7) 12 (25.5) 4 (8.5) 47 (100)

Total 19 (11.1) 0 (0) 23 (13.4) 102 (59.6) 27 (15.8) 171 (100) February 2003 sampling Fishing Creek at Wesconnet Boulevard

(02246435) 1 (2.4) 0 (0) 11 (26.2) 3 (7.1) 27 (64.3) 42 (100)

Fishing Creek at 110 thStreet

(0226437) 0 (0) 0 (0) 14 (29.8) 2 (4.3) 31 (66) 47 (100)

South Branch Big Fishweir Creek

at Casssat Avenue (02246465) 0 (0) 0 (0) 3 (6.2) 34 (70.8) 11 (22.9) 48 (100)

South Branch Big Fishweir Creek

at Blanding Boulevard (02246467) 0 (0) 0 (0) 7 (14.9) 27 (57.4) 13 (27.7) 47 (100)

Total 1 (0.5) 0 (0) 35 (19) 66 (35.9) 82 (44.6) 184 (100)