DISSOLVED OXYGEN CONCENTRATIONS, 1999 - 2000

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River

LEON CO.

WAKULLA CO.

WAKULLA CO.

LEON CO.

FRANKLIN CO.

Panacea

Woodville

Crawfordville

Jackson

Ochlockonee

St. Marks

River

Lake

Lafayette

Lake

GADSDEN CO.

Apalachicola

National

Forest

Marks

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0.1 0.2

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7.3

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6.2

0.1

1.2

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2.8

6.3

1.8

8.5

5.6

1.3

0.3

0.1

0.7

0.4

0.6 0.1

0.1 0.1

0.3

0.1

3.5

0.1

8.3

0.1

1.1

1.5

2.2

0.1

7.2

4.0

9.3

3.7

9.2

11.9

10.6

Lake Talquin

L.

Miccosukee

Lake

Munson

Wakulla 

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St. Marks

Rise

Y Spring

 Creek

0 510

Miles

N

(Concentration mg-O/L)

$T SW Sampling Location

#S GW Sampling Location

Y Springs

District Boundary

County Boundary

U.S. Highways

Rivers

Conduit System

State/County Roads

Lakes

Incorporated Areas

Public Lands

01-06-018

FIGURE 39
pH, 1999 - 2000

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River

LEON CO.

WAKULLA CO.

WAKULLA CO.

LEON CO.

FRANKLIN CO.

Panacea

Woodville

Crawfordville

Jackson

Ochlockonee

St. Marks

River

Lake

Lafayette

Lake

GADSDEN CO.

Apalachicola

National

Forest

Marks

St.

Midway

Sopchoppy

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Newport

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Tallahassee

River

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JEFFERSON CO.

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7.8

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7.7

7.4

7.2

7.3

7.5

7.6 7.2

8.1

7.3

7.6

7.4

7.7

7.8

7.8

7.5

7.4

7.5

7.5

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7.7

6.7

5.3

6.4

3.5

Lake Talquin

St. Marks

Rise

Lake

Munson

L.

Miccosukee

Y Spring

 Creek

0 510

Miles

N

$T SW Sampling Location

#S GW Sampling Location

Y Springs

District Boundary Lakes

Incorporated Areas

Public Lands

County Boundary

U.S. Highways

Rivers

Conduit System

State/County Roads

01-06-019

FIGURE 40
 61

All remaining ground water sites had pH values between 6.8 to 8.5 su. pH was generally higher 

with increasing well depth. 

Specific Conductance 

Specific conductance levels were measured in the field coincident with sampling. Levels ranged 

from 41 to 130 μmhos/cm in surface water inflows (Lost Creek, Fisher Creek, Ames Sink, Figure 

41). Levels in surface water outflows (Middle River Sink, Wakulla Springs, Sally Ward Spring 

and McBride Slough) range from 211 to 337 μmhos/cm. Ground water levels ranged from 60 to 

1,180 μmhos/cm. The ground water median specific conductance was 291 μmhos/cm. 

Orthophosphate 

Samples were analyzed for orthophosphate (PO4-P) in the laboratory. Levels ranged from 0.01 

to 0.64 mg/L with a median value of 0.03 mg/L (Figure 42). The median value for ground water 

(0.02 mg/L) is lower than the median value for surface water (0.04 mg/L), but the highest values 

were in some wells near the coast. 

Nitrate Concentrations as a Function of Time

City of Tallahassee Public Supply Wells 

The City of Tallahassee provided NO2+NO3-N data for 29 Floridan Aquifer public supply wells in 

their system (Appendix A, Table A5, Figure 43). Due to their relatively long open-hole intervals, 

regular pumping, long periods of record, large zones of contribution and high discharge 

volumes, these wells are of particular interest. Specifically, the data represent the best 

available insight into the spatial distribution of NO2+NO3-N in the Floridan Aquifer beneath the 

semi-confined portion of the study area. Data collection for some wells began in the early 

1980s. Others began at various times since. Data given in Figure 44 for Woodville #1 and #2 

were supplemented by three data points (Woodville #1 on 7/14/1980 and Woodville #2 on 

1/19/1978 and 7/14/1980) obtained from FDEP (Cliff McKeown, personal communication, 

2001). 

NO2+NO3-N concentrations in individual wells are relatively invariant as a function of time 

(Figure 44). Statistical analyses of these time series were performed using Spearman and 

Kendall tau correlation statistics (Katz, personal communication, 2001). Seventeen of the 29 

wells showed no statistically significant trend. Seven wells (#10, #12, #17, #20, #21, #22, and 

#27) showed a slight increasing trend (p<0.05) in NO2+NO3-N levels over time. Five wells (#7, 

#13, #15, #19, and #23) showed a slight decreasing trend (p<0.05). Wells #12, #17 and #27 

are located in the southeast quadrant of the city, within the city limits. Wells #20, #21 and #22 

are located near the intersection of Highway 90E and I-10 and lie within about one mile of each 

other. There is a high concentration of septic tanks in the immediate vicinity of these wells. The 

declining wells lie in the northwest quadrant of the city, south and east of Lake Jackson. 

Data from the 29 City of Tallahassee wells were then aggregated in several subsets based on 

location. The semi-confined well data set (716 values from 27 wells, excluding the two 

Woodville wells) showed no significant trend in NO2+NO3-N concentration over time. The 

median concentration from this set of wells is 0.33 mg-N/L (n=716, mean=0.35, stdev=0.17). 

For the 20 City of Tallahassee wells south of I-10, the median concentration was 0.36 mg-N/L 

(n=556, mean=0.38, stdev=0.16). Lastly, the six southernmost wells (south of Tram 

Road/Orange Avenue and adjacent to the Cody Scarp) had a median concentration of 0.48 mgN/L (n=208, mean=0.48, stdev=0.16). These results show an increasing trend in NO2+NO3-N 

from north to south in Leon County under the semi-confining unit. 
SPECIFIC CONDUCTIVITY, 1999 - 2000

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LEON CO.

WAKULLA CO.

WAKULLA CO.

LEON CO.

FRANKLIN CO.

Panacea

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Crawfordville

Jackson

Ochlockonee

St. Marks

River

Lake

Lafayette

Lake

GADSDEN CO.

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(Specific Conductance umhos/cm)

$T SW Sampling Location

#S GW Sampling Location

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District Boundary

County Boundary

U.S. Highways

Rivers

Conduit System

State/County Roads

Lakes

Incorporated Areas

Public Lands

01-06-020

FIGURE 41
ORTHOPHOSPHATE CONCENTRATION, 1999 - 2000

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LEON CO.

WAKULLA CO.

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LEON CO.

FRANKLIN CO.

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Crawfordville

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Ochlockonee

St. Marks

River

Lake

Lafayette

Lake

GADSDEN CO.

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0.03

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Lake

Munson

St. Marks Wakulla Rise Springs

Y Spring

 Creek

0 510

Miles

N

(Concentration mg-P/L)

$T SW Sampling Location

#S GW Sampling Location

Y Springs

District Boundary

Lakes

Incorporated Areas

Public Lands

County Boundary

U.S. Highways

Rivers

Conduit System

State/County Roads

01-06-021

FIGURE 42
Y

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GEORGIA

A P A L A C H E E

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1007

2043 2106

2196 2333 2375 2377 2621 2573 2692 27072708 2706

2782 2863 2957

2990

3013

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LOCATION OF CITY OF TALLAHASSEE PUBLIC SUPPLY WELLS

Well Locations

Major Lakes

Incorporated Areas 

Public lands

Rivers

U. S. Highways

County/State Roads

(X

0 5

Miles

01-06-022

FIGURE 43
 65

Figure 44. City of Tallahassee Public Supply Well NO2+NO3-N Concentrations (mg/L). 

Tallahassee Well #30 (3940) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19921992199319931994199419951995199619961997199719981998

Tallahassee Well #25 (3691) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1990199119921993199419951996199719981999

Tallahassee Well #29 (3522) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

199119921993199419951996199719981999

Tallahassee Well #18 (3379) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

198219841986198819901992199419961998

Tallahassee Well #16 (3181) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

198219841986198819901992199419961998

Tallahassee Well #20 (3028) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1986198719881989199019911992199319941995199619971998

Tallahassee Well #21 (3013) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1990199119921993199419951996199719981999

Tallahassee Well #22 (2990) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

198719881989199019911992199319941995199619971998
 66

Figure 44. City of Tallahassee Public Supply Well NO2+NO3-N Concentrations (mg/L) [cont.] 

Tallahassee Well #11 (3108) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

198319851987198919911993199519971999

Tallahassee Well #19 (3021) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

198219841986198819901992199419961998

Tallahassee Well #23 (2957) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19841986198819901992199419961998

Tallahassee Well #26 (5851) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

199119921993199419951996199719981999

Tallahassee Well #13 (2742) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

198219841986198819901992199419961998

Tallahassee Well #8 (2863) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19831985198719891991199319951997

Tallahassee Well #6 (2708) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19831985198719891991199319951997

Tallahassee Well #7 (2707) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19831985198719891991199319951997
 67

Figure 44. City of Tallahassee Public Supply Well NO2+NO3-N Concentrations (mg/L) [cont.] 

Tallahassee Well #10 (2782) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

198319851987198919911993199519971999

Tallahassee Well #4 (2706) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19831985198719891991199319951997

Tallahassee Well #2 (2692) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19831985198719891991199319951997

Tallahassee Well #5 (2621) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19831985198719891991199319951997

Tallahassee Well #9 (2573) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19831985198719891991199319951997

Tallahassee Well #1 (2377) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19831985198719891991199319951997

Tallahassee Well #3 (2333) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19831985198719891991199319951997
 68

Figure 44. City of Tallahassee Public Supply Well NO2+NO3-N Concentrations (mg/L) [cont.] 

Tallahassee Well #15 (2375) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

198219841986198819901992199419961998

Tallahassee Well #17 (2196) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

198219841986198819901992199419961998

Tallahassee Well #12 (2106) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

198319851987198919911993199519971999

Tallahassee Well #27 (2043) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

199019911992199319941995199619971998

Woodville Well #1 (998) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1980198219841986198819901992199419961998

Woodville Well #2 (1007) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

19781980198219841986198819901992199419961998
 69

NITROGEN SOURCE INVENTORY 

One of the primary objectives of this study was to quantify the various inputs of nitrogen to the 

landscape of Leon and Wakulla counties. Six principal nitrogen inputs to the hydrosphere were 

investigated: atmospheric deposition, wastewater treatment facilities (WWTF), on-site domestic 

disposal systems (OSDS), commercial fertilizer application, livestock and sinking streams. 

Nitrogen derivative of atmospheric deposition is predominantly inorganic (IN) and has both a 

dissolved and a particulate aspect. Commercial fertilizers are also predominantly inorganic. 

They are typically applied to the landscape in particulate form. However, to be bio-available, the 

N they contain is water-soluble. Solubility makes this source of inorganic N available for 

dispersal in the environment via surface water runoff and rainfall infiltration to ground water. 

WWTFs and OSDS take what is predominantly particulate organic N (ON) suspended in water 

and treat it by (1) providing partial denitrification, (2) converting organic N to inorganic forms 

(predominately NO3), and (3) sequestering some N in particulate form. WWTF are more 

efficient at providing denitrification than are OSDS. N-containing wastewater from these 

systems is applied either to or beneath the land surface for disposal. In the case of a WWTF, 

land application provides opportunities for vegetative N uptake, microbial transformation and 

other forms of N removal. Eventually, the disposed water reaches the water table, carrying 

some fraction of its original N load. Livestock apply organic N directly to the landscape. Sinking 

streams carry nitrogen in predominantly organic form. Further, this load is partitioned between 

dissolved and particulate forms. 

For each source the total nitrogen load (as N) was estimated and is presented here. As 

applicable to the particular source, these estimates represent the summation of constituent 

forms (DIN, PIN, DON, and PON). For each source, most of the N is presumed to be present in 

one or two of these forms. However, the exact partitioning among DIN, DON, PIN and PON is 

poorly understood. Annual loads were estimated during the period 1970 through 1999 (Figure 

45). Conditions as of 1999 are summarized below. 

A number of different data sources were used to prepare the nitrogen load estimates given 

below. Consequently, the quality of data underlying the estimates is quite variable. Some data 

(WWTFs) are generally complete, accurate and reliable. Other data are either incomplete 

(primarily) or of poor quality. This necessitated estimation and/or interpolation strategies in 

order to prepare load estimates. Estimation and interpolation techniques are described in the 

relevant text sections. Such approaches were unavoidable. Future nitrogen inventory efforts 

will benefit from accurate record keeping pertaining to all sources, not just WWTF. 

The sources characterized through this investigation represent a continuum of “intensities” that 

range from relatively low, when expressed on a mass per unit area basis, to direct introductions 

into the Floridan Aquifer. At the scale of the study area, atmospheric deposition provides the 

largest total N load but probably the lowest mass per unit area (M/L2

) application, ~5 kg-N/ha-yr. 

Relatively low M/L2

 application rates provide the greatest opportunity for denitrification via 

vegetative uptake, microbial transformations, etc. This is particularly true when the N is applied 

to the soil surface. Given the lack of concentrated livestock feeding operations in the study area 

and the direct application of the existing application to the top of the soil profile, livestock N 

loading also represents (on a M/L2

 basis) a relatively low intensity application. 

WWTF represent a relatively intense N application. Based on effluent N loading estimates at 

the City of Tallahassee SESF and an estimated application area of 600 ha (1,500 acres), 

effluent spraying delivers N at a rate of about 550 kg-N/ha-yr. This does not account for the 

additional load derivative of IN application to support crop production at the SESF. 
 70

5. Summary of Nitrogen Loading to the Semi-confined and Unconfined Areas as a Function of Time 

1975 1980 1985 1990 1995

Date

WWTF (Mkg)Com Fert (Mkg)Atm dep (Mkg)OSDS (Mkg)Livestock (Mkg)Residuals (Mkg)
 71

OSDS represent an intense N application. Based on estimated OSDS annual N loads between 

2 and 6 kg-N/year per capita and a drain field area of 625 ft2

, ODSD application rates equate to 

between 800 and 2,400 kg-N/ha-yr. OSDS are know to be effective at both nitrifying and at 

delivering NO3 to ground water. Release of wastewater beneath the most biologically active 

portion of the soil profile facilitates NO3 delivery to ground water. 

Commercial fertilizer applications also represent a significant step up in application intensity. In 

farming operations, application rates are in the 100s of kg-N/ha-yr. Residential application rates 

are similar. This N source is available for leaching into the soil profile where it is subject to 

vegetative uptake, microbial transformation, etc. and/or transport to the underlying ground 

water, or off-site removal via surface water runoff. Given the large number of closed lake basins 

in Leon County, some (unknown) fraction of N from this source is being sequestered in lakes 

and lake-bottom sediments. Historically, the majority of the IN fertilizer load applied in the study 

area was on semi-confined Leon County. Presumably, the fraction of this load that reached the 

Floridan Aquifer is reflected in the 0.2 to 0.4 mg/L NO2+NO3 presently seen in Floridan Aquifer 

water beneath semi-confined Leon County. 

It is important to recognize that application of nitrogen to the landscape is not the same as its 

introduction into the Floridan Aquifer. Nitrogen is a highly reactive element. Further, depending 

on the source, the pathways N travels to reach Floridan Aquifer ground water are quite variable. 

Various natural processes act on anthropogenic N to provide denitrification. Numerous 

transformations, reaction pathways and uptakes can either temporarily sequester nitrogen in 

vegetation, lake-bottom sediments or the subsurface, or return it to the atmosphere. Only part 

of the nitrogen introduced to the landscape eventually reaches the Floridan Aquifer. Given the 

current state of knowledge, little is known about source-specific or pathway-specific nitrogen 

removal efficiencies in this environment. Based on data presented here, it appears that much of 

the total nitrogen load applied to these two counties is either being sequestered or returned to 

the atmosphere. 

Atmospheric Deposition

The Earth’s atmosphere is approximately 78.93 percent nitrogen. The amount of atmospheric 

nitrogen is affected by human activities—primarily the burning of fossil fuels (e.g. automobiles, 

power production, etc.). Nitrogen from the atmosphere is deposited on the land surface both 

dissolved in rain and as dry deposition.

To monitor nitrogen deposition rates, the National Atmospheric Deposition Program (NADP) 

was established in the late 1970s. An NADP wet-deposition site has been operated in Quincy 

since 1984, with chemical analyses being performed by the USGS. Annual (1984 to 1999) wet 

deposition loading rates for inorganic nitrogen (NO3-N and NH4-N, dissolved) ranged between 

2.03 kg/ha and 3.92 kg/ha. These rates equate to annual average dissolved inorganic nitrogen 

(DIN) concentrations in rainfall between 0.15 mg/L and 0.28 mg/L. The observed 1999 DIN load 

was 2.36 kg/ha. The period of record average load was 2.87 kg-N/ha-yr. 

Dry deposition is not measured at the NADP site. Rather, for the purposes of this study it was 

estimated as 96 percent of wet deposition (Baker, 1991). 1.96 times the observed 1999 wet 

load was used as the annual total inorganic N (TIN) load for 1999, 4.63 kg-N/ha-yr. 1.96 times 

the period-of-record average annual wet load was used as the period-of-record TIN load, or 

5.63 kg-N/ha-yr. This average was used to estimate annual loads prior to 1984, during which 

no observations were available. 
 72

Rainfall, together with its DIN load, falls on the landscape and is subject to evaporation, 

transpiration, runoff and infiltration. Inorganic nitrogen being transported through the soil as a 

component of recharge is subject to uptake by plants, microbial transformations and other 

processes that remove nitrogen from the infiltrating water. Some sense of the efficiency of the 

soil at removing nitrogen from recharge can be obtained by comparing rainfall DIN 

concentrations with concentrations in ground water lying immediately beneath the land surface 

and otherwise unaffected by anthropogenic nitrogen inputs. The processes controlling the fate 

of dry deposition N are somewhat different. This N must be re-mobilized by infiltrating rainfall 

before it becomes available for uptake or transformation in the soil, or recharge to ground water. 

NO2+NO3-N (dissolved) and NH4-N (dissolved) data from surficial aquifer wells in Leon and 

Wakulla counties were examined to gain insight into the fate of N applied to the landscape via 

atmospheric deposition. Data from 9 wells, having depths ranging between 15 and 58 ft, were 

evaluated. Six wells are completed in undifferentiated sands overlying the confined Floridan 

Aquifer in western Leon and Wakulla counties. Land use in this area is predominantly 

silvaculture and, presumably, these wells should be little affected by septic tanks or other 

sources of anthropogenic nitrogen. The remaining three are completed in sandy intervals within 

the Miccosukee formation in semi-confined Leon County. 

A total of 48 NO2+NO3-N (dissolved) and analyses were available. Sample collection dates 

ranged between 07/89 and 07/99. 16 of 48 NO2+NO3-N analyses were below their respective 

method detection limits. Of the 32 above MDL analyses, three samples (from one well located 

in semi-confined Leon County) seemed to reflect the impact of a local source of NO2+NO3-N on 

ground water. These data ranged between 1.7 mg/L-N and 2.1 mg/L-N and were excluded from 

further analysis. The remaining 29 values had a median concentration of 0.02 mg/L-N 

(mean=0.038, stdev=0.052). 

From the same set of wells and for the period 06/93 to 07/99, 26 NH4-N (dissolved) analyses 

were available. Of these, 10 were below the minimum detection limit. Three analyses (all from 

the same well and ranging between 0.8 and 1.3 mg/L) appeared to be outliers and were 

excluded from further analysis. This well was also located in semi-confined Leon County. The 

remaining 12 values had a median of 0.019 mg/L (mean=0.028, stdev=0.024). 

Annual average rainfall DIN concentrations ranged between 0.15 and 0.28 mg/L at the Quincy 

NADP site (1984 to 1999). During the same period ground waters from the surficial aquifer had 

NO2+NO3 and NH4 concentrations generally below or slightly above their respective method 

detection limits. Comparing medians for these parameters to DIN concentrations in rainfall 

suggests that the soil profile is capable of removing about 80 percent of the DIN in rainfall. If 

the impact of re-mobilized N from dry deposition is included, the soil’s N removal efficiency is 

even greater. 

Approximately 103,491 hectares (ha) lie in the semi-confined part of Leon County and 112,903 

ha in the unconfined part of Leon and Wakulla counties (Figure 1). Using these areas, the 

observed annual wet deposition loading rate, and the assumed constant ratio of wet to dry 

deposition, annual total loads were calculated for 1984 through 1999. For years prior to 1984, 

the period-of-record average annual total load was used. For 1999 the total loading rate is 4.63 

kg-N/ha-yr, resulting in a total load to the semi-confined area of 479,000 kg-N/yr. The total load 

to the unconfined area is 523,000 kg-N/yr. 
 73

Table 5. Estimated 1999 Nitrogen Loading from Atmospheric Deposition. 

Area Area (ha) kg-N/ha-yr kg-N/yr 

Semi-confined 103,491 4.63 479,000 

Unconfined 112,903 4.63 523,000 
 74

Wastewater Treatment Facilities

According to FDEP records, there are 69 wastewater treatment facilities (WWTFs) in Leon and 

Wakulla counties (Appendix A, Table A6, Figure 46). Of the 59 within the semi-confined and 

unconfined areas, 21 are domestic WWTF and 38 are industrial WWTFs. The total design 

capacity of the WWTFs, domestic and industrial, is 38.05 Mgal/d. The majority of this capacity 

(32.06 Mgal/d) is for domestic plants operated by the City of Tallahassee. The remaining 

facilities have a combined capacity of slightly less than six Mgal/d. 

Industrial WWTF Effluent 

The industrial WWTFs discharge from systems used for vehicle washing, ground water 

remediation or for non-contact heating/cooling purposes. These facilities are not monitored for 

nitrogen because elevated concentrations are not anticipated as a result of their operations. 

Most water quality concerns at the industrial WWTFs center around volatile organic compounds 

(VOCs) rather than nutrients. With the exception of one industrial facility, no estimates were 

made of nitrogen contributions from these facilities. 

The one industrial WWTF that is an exception is Primex, a large black-powder production facility 

located in southern Wakulla County. Presently, Primex discharges effluent with elevated 

nitrogen levels to surface waters in Wakulla County. Primex is located near St. Marks and is 

adjacent to the lower Wakulla River. Effluent is held in a polishing pond prior to being sprayed 

onto an eight-acre sprayfield. Overland flow from the sprayfield passes through a swampy area 

and enters a ditch leading to Big Boggy Branch and, eventually, into the Wakulla River just north 

of its confluence with the St. Marks River. 

FDEP provided monthly averages of total nitrogen concentration (as N) and effluent flows at the 

point where it discharges into Big Boggy Branch. From 1992 to 2000 monthly average nitrogen 

concentrations varied from 1.5 to 56.9 mg/L. Estimated annual loads for this period ranging 

between 4,819 and 31,096 kg-N/yr entered Big Boggy Branch, with recent loads being highest. 

Mitigation of this source will occur when Primex begins diverting its effluent to the City of 

Tallahassee Purdom Generating Station for use in the power station’s cooling system. This 

action is anticipated during 2001. Any effluent remaining after this diversion will go to an 

evaporation unit at the power plant where the nitrogen will be volatilized. This will effectively 

remove from surface waters of the basin any direct nitrogen discharge from the Primex 

industrial WWTF. 

Domestic WWTF Effluent 

Domestic facilities receive wastewater, treat it using any of several methods and then discharge 

the treated effluent largely to percolation ponds or sprayfields for disposal (Figure 46). 

Domestic WWTFs have much more (and better) nitrogen discharge data available than do 

industrial WWTFs. The City of Tallahassee provided average annual TN concentrations and 

annual facility flows back to 1970. Data from other facilities were much less complete. Data for 

facilities other than City of Tallahassee were not readily available prior to 1992. Sufficient data 

were not available to make estimates for all facilities for all years between 1992 and 1999. For 

the domestic facilities other than City of Tallahassee and Winco Utilities, Inc. the most complete 

data set was for 1993. Winco Utilities is located south of Woodville in Wakulla County and 

provides water for prison and the industrial park. 
WASTEWATER TREATMENT FACILITY LOCATIONS WITH

MAJOR EFFLUENT AND RESIDUAL DISPOSAL AREAS

%U

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Y

St. Marks

Tallahassee

A P A L A C H E E

B A Y

Crawfordville

Sopchoppy

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#

##

Wa

#

kulla

River

Midway

#

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# Petty 2 #

Young

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# #

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LEON CO.

WAKULLA CO.

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JEFFERSON CO.

TAYLOR

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GADSDEN CO.

FRANKLIN CO.

Woodville

Wakulla 

 Springs

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N

Effluent Disposal Areas

Residual Disposal Areas

Public Lands

Incorporated Areas

Domestic Waste Facility

Locations U%

Industrial Waste Facility

Locations U% District Boundary

County Boundary

State/County Roads

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U.S. Highways

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01-06-023

FIGURE 46
 76

Using available FDEP compliance data and data provided by the City of Tallahassee, annual TN 

loads were estimated (Appendix A, Table A7) for 21 domestic WWTF for 1992 through 1999. 

When estimating annual loads, average monthly values of flow and TN concentration were used 

where possible. In some cases, maximum monthly concentrations were used, as they were the 

only data available. Six of 21 facilities had sufficient monthly flow and concentration data from 

which to calculate monthly N loads. For these cases monthly N loads were then aggregated 

into the annual loads given in Appendix A, Table A7. Six facilities had monthly flow data but no 

monthly total N concentration data. For these cases monthly TN data from another facility were 

used as an estimate of the unavailable data. Eight facilities had neither flow nor concentration 

data. For these cases, total monthly N load from similar facilities was scaled up or down 

according to the ratio of design flow capacities of the two respective facilities. City of 

Tallahassee annual load estimates (1970 to 1999) were the product of average annual TN and 

annual flow. 

TN and flow data were most complete for the small WWTFs in 1993. In this year the small 

WWTFs contributed about 4 percent of the total TN load with the City of Tallahassee 

contributing the remainder. Annual TN load estimates from WWTF effluent (Figure 45) consist 

of calculated City of Tallahassee loads from 1970 to 1999, calculated loads from small WWTF 

from 1992 to 1999 and estimated small WWTF loads prior to 1992. Between 1970 and 1992 

the annual TN load for both the City of Tallahassee and the small WWTFs was estimated as 

104 percent of the City of Tallahassee annual load. 

1999 TN loads by semi-confined and unconfined areas are summarized in Table 6. Small 

WWTF loads from 1993 were used to estimate 1999 conditions. For City of Tallahassee and 

Winco Utilities, Inc. 1999 data were available and are used in the totals below. 

Table 6. Estimated 1999 Nitrogen Loading from WWTF Effluent 

Area Industrial (kg-N/yr) Domestic (kg-N/yr) Total (kg-N/yr) 

Leon Semi-confined -- 8,700 8,700 

Leon Unconfined -- 326,000 326,000 

Wakulla Unconfined 31,000 4,800 35,800 

City of Tallahassee WWTF Development History 

The largest WWTF total N load originates from facilities operated by the City of Tallahassee. 

This is not surprising given the scale of total flow through City of Tallahassee facilities as 

compared to other, smaller facilities. City of Tallahassee facilities serve a significant percentage 

of the population in Leon County. Their facilities represent about 80 percent of the total design 

flow capacity for domestic and industrial WWTFs in Leon and Wakulla counties and 96 percent 

of the estimated domestic WWTF total N load. Given the relative scale of the City of 

Tallahassee discharge, the significance of this discharge to the total nitrogen budget of the 

study area, and the high quality of available data characterizing the discharge, it was possible to 

assemble a more complete picture of the history of N discharges from City of Tallahassee 

facilities. 

A number of environmental laws passed in the late 1960s and early 1970s were aimed at 

improving and protecting surface water quality. A significant component of this effort involved 

the removal of point source discharges from surface waters. In Leon County, Federal regulators 

assigned Lake Munson a Waste Load Allocation of “zero” pollutants. The Water Pollution 

Control Act Amendments of 1972 (P.L. 92-500) mandated “no discharge of pollutants to 
 77

navigable water by 1985”. Also in this time period, USEPA implemented the NPDES program. 

Federal grant funds were made available to local communities to convert surface water effluent 

discharges to land application. These programs and environmental concerns associated with 

discharge of domestic waste to Munson Slough prompted the City of Tallahassee to move 

forward with the spray irrigation facility that could eventually handle all the City’s effluent (Keith 

Turner, City of Tallahassee, personal communication, 2001; Pruitt et. al, 1988). 

The first central sewers in Tallahassee were installed in 1904 to serve the downtown 

commercial district and the Florida State College for Women (now Florida State University). 

These sewers discharged to two septic tanks for treatment. The first WWTF (1.0 Mgal/d) was 

constructed on Lake Bradford Road in 1933 and discharged to a tributary of Lake Munson. The 

Federal Correctional Institution constructed their own WWTF at Capital Circle and Park Avenue 

which discharged into Lake Lafayette until 1967, when the facility connected to the City of 

Tallahassee sewer. Effluent discharge in the Lake Munson Basin increased in 1941 with the 

U.S. Army’s construction of a WWTF (1 Mgal/d) to serve Dale Mabry Field. After deactivation of 

the military post, the City took over the WWTF and continued to operate it through 1982. Lake 

Munson was impounded in 1950 to alleviate downstream flooding problems (Bocz and Hand, 

1985) and a new, higher capacity plant (4.5 Mgal/d) was constructed on Lake Bradford road in 

1951. In 1961, a 0.06 Mgal/d capacity high-rate trickling filter system was constructed at the 

municipal airport to process effluent, which was discharged to rapid infiltration basins (Keith 

Turner, City of Tallahassee, personal communication, 2001). 

Lake Munson showed the effects of the increasing amounts of stormwater and effluent it 

received from the City of Tallahassee with massive algal blooms reported as early as 1956 and 

1963 (Beck, 1963). In 1964 the City completed a land exchange with the US Forest Service 

that gave them the area at Capital Circle and Springhill Road for a WWTF site. Construction of 

the Southwest Plant (2.5 Mgal/d) was completed in 1966 with effluent discharge to Munson 

Slough. A 6.5 ha (16 acre) experimental irrigation system was also provided for effluent 

disposal at the site and research began into the effects and benefits of spray application. This 

sprayfield represented the beginning of what is now the Southwest Sprayfield (SWSF) and all 

flow through the plant was disposed of through spray application. The sprayfield area was 

expanded in 1972 to 15.6 ha (38.5 acres) and again in 1977 to 48 ha (118.5 acres) (Keith 

Turner, City of Tallahassee, personal communication, 2001). Spray effluent disposal to uplands 

provided the opportunity to mitigate adverse impacts experienced by Lake Munson as a result of 

surface water discharge. Since the diversion of effluent out of the lake occurred, it has 

experienced a significant improvement in water quality. 

Spray application of treated wastewater effluent at the Southwest plant averaged 0.25 Mgal/d in 

1966. By 1969 the average flow through the plant had risen to one Mgal/d and by 1974 the 

average flow had increased to 3.5 Mgal/d—exceeding the plant capacity. As a result, plant 

capacity was increased to 10 Mgal/d in 1974 and the WWTF was officially named Thomas P. 

Smith Plant. This new plant used an activated sludge method of treatment, which resulted in 

immediate changes in effluent water quality. Total nitrogen in the effluent did not change but 

NO3-N increased to approximately four times levels in the high-rate trickling filter process. This 

conversion of ammonia and Kjeldahl nitrogen to NO3-N prior to land application ensures that the 

nitrogen is in a form to be utilized by vegetation and prevents potentially more harmful ammonia 

from entering ground water (Overman, 1979). 
 78

Southeast Sprayfield 

In 1981, the Southeast Sprayfield (SESF) was put into operation on Tram Road approximately 

1.6 miles east of Capital Circle SE. The site is located just south of the Cody Scarp on the Gulf 

Coastal Lowlands. It originally consisted of 405 ha (1,000 acres). In 1982, 202 ha (500 acres) 

were added. 160 ha (396 acres) were added in 1986. With the 1986 expansion, all treated 

effluent discharge to the Lake Munson Drainage basin ceased. In 1999, another 106 ha (266 

acres) were added to the SESF, bringing the total acreage to 873 ha (2,159 acres). The latest 

addition is referred to as the SESF extension. Since its inception, the SESF has been actively 

farmed. Over the years and as a part of farming operations, inorganic fertilizers have been 

applied to promote crop growth. 

There are records of 69 monitor wells having been constructed at the SESF (Appendix A, Table 

A8, Figure 47). All are Floridan Aquifer wells except SE28 through SE36 (nine surficial aquifer 

wells) and SE54 through SE70 (17 surficial aquifer wells). 

Given the scope of activities conducted at the SESF, a number of wells are presently being 

sampled, as required by permit or at the discretion of the City of Tallahassee. As required by 

permit, eleven wells (eight Floridan Aquifer, SE2, SE15, SE16, SE17, SE19, SE22A, SE52, 

SE53, and three surficial aquifer wells, SE30, SE31 and SE34) are currently being sampled. 

The City is also required, by permit, to sample 10 Floridan Aquifer wells (SE75 through SE84) at 

the SESF extension. SE85 and SE86 are presently sampled at the discretion of the City of 

Tallahassee. 

Sampling results from eight SESF monitor wells are given in Figure 48. All data were obtained 

from USGS and City of Tallahassee databases and represent analyses for NO2+NO3-N, total. 

Data from these wells are quite variable, as would be expected given the wide variability in N 

application rates over short spatial and temporal scales. SE16 and SE17 are consistently below 

0.6 mg/L. SE15 shows a slight increasing trend with time; concentrations are typically less that 

1 mg/L. SE02 shows a strongly increasing trend with time, going from about 0.5 mg/L in the 

early 1980s to between 4 and 5 mg/L now. SE22A is clearly under the influence of effluent 

disposal and/or IN fertilizer application. SE19, SE52 and SE53 are of interest, in that they show 

a rapid concentration run-up from the mid-1980s to 1990. Around 1990 concentrations peaked 

in the range of 6 to 8 mg/L. Since 1990, they have declined slightly and are now in the 4 to 6 

mg/L range, where they have been since about 1994. 

Results from six SESF extension monitor wells (SE77, SE78, SE79, SE80, SE81 and SE86) are 

also given in Figure 48. Data from these wells are variable, with no concentration exceeding 2 

mg/L-N. SE75, SE76, and SE82 through SE85 are not presented, as they are largely below 

detection limits. Among SE75, SE76 and SE82 through SE85 there were only 8 detections in 

42 samples. Excluding the initial samples, which appear to be anomalous, the highest 

NO2+NO3-N result obtained from these wells was 0.052 mg/L. 

Sampling of City of Tallahassee public supply well CW-12 is required for background purposes. 

“SES”, the Floridan Aquifer potable supply well for the facility, is presently sampled quarterly. 

The City has recently begun to sample the “SE Farmers Well” as well. Two off-site privately 

owned domestic wells are also being sampled. The “Messer” well has been sampled since 

1975. Sampling of the “Barker” well began in 1999. Both wells are up-gradient of the SESF 

and show NO3-N levels ranging from below detection limits to 0.44 mg/L. 
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SE23 (1149)

SE50 (1150)

SE17 (1165)

SE16 (1166)

SE02 (1156)

SE22 (1164)

SE10 (1172)

SE20 (1163)

SE46 (1183)

SE47 (1184)

SE43 (1208)

SE44 (1209)

SE37 (1223)

SE38 (1224)

SE03 (1232) SE39 (1225) SE01 (1233)

SE19 (1240)

SE18 (1288)

SE14 (1289)

SE15 (1209)

SE68 (1291) SE49 (1307)

SE40 (1311) SE41 (1312)

SE42 (1313)

SE06 (1333)

SE07 (1334)

SE48 (1344)

SE53 (7223)

SE28 (7279)

SE30 (7281)

SE31 (7282)

SE33 (7283)

SE52 (7285)

SE54 (7290)

SE55 (7291)

SE58 (7293)

SE59 (7294)

SE60 (7295)

SE61 (7296)

SE62 (7297)

SE63 (7298)

SE64 (7299)

SE65 (7300)

SE67 (7302)

SE69 (7303)

SE70 (7304)

SE57 (1185)

SE05 (1348)

SE11N (7268)

SE11S (7269)

SE24 (1153)

SE09 (1171)

SE45 (1210)

SE29 (7280)

SE34 (7284)

SE56 (7292)

SE66 (7301)

SE22A (7270)

Tram Rd

SE FARMERS WELL

SE77 (7866)

SE78 (7867)

SE82 (7871)

SE81 (7870)

SE83 (7872) SE84 (7873)

MESSER WELL

SE75 (7864)

SE76 (7865)

SE79 (7868)

SE80 (7869)

SE85 (7874)

SE86(7875)

#

BARKER WELL

SE12 (1352)

#S Southeast Monitor Well Sites

SOUTHEAST SPRAYFIELD MONITOR WELL LOCATIONS

N

Miles

0 0.5 1

1999 Imagery (DOQQ's)

01-06-024

FIGURE 47
 80

Figure 48. Southeast Sprayfield Monitor Well NO2+NO3-N Concentrations (mg/L) 

SE02 (1156)

0

1

2

3

4

5

6

19801982198419861988199019921994199619982000

SE15 (1209)

0

2

4

6

8

10

1980198219841986198819901992199419961998

SE17 (1165)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

1980198219841986198819901992199419961998

SE22A (7270)

0

1

2

3

4

5

6

7

8

9

199219931994199519961997199819992000

SE52 (7285)

0

2

4

6

8

10

12

14

19861988199019921994199619982000

SE53 (7223)

0

1

2

3

4

5

6

7

8

9

19861988199019921994199619982000

SE19 (1240)

0

2

4

6

8

10

12

1980198219841986198819901992199419961998

SE16 (1166)

0

0.1

0.2

0.3

0.4

0.5

1981198319851987198919911993199519971999
 81

Figure 48. Southeast Sprayfield Monitor Well NO2+NO3-N Concentrations (mg/L) [cont.] 

SE77 (7866)

0

0.2

0.4

0.6

0.8

1

19991999199919991999200020002000

SE78 (7867)

0

0.2

0.4

0.6

0.8

1

1999199919992000200020002000200020002000

SE79 (7868)

0

0.2

0.4

0.6

0.8

1

19991999199919991999200020002000

SE80 (7869)

0

0.2

0.4

0.6

0.8

1

19991999199919991999200020002000

SE81 (7870)

0

0.5

1

1.5

2

19991999199919991999200020002000

SE86 (7875)

0

0.2

0.4

0.6

0.8

1

19991999199919991999200020002000
 82

Southwest Sprayfield 

SWSF has shrunk in the years since 1977 and its spray application area is currently 36 ha (89 

acres). There are 43 monitor wells on record as having been constructed at or near the site 

(Appendix A, Table A9, Figure 49). The City is presently required to sample three Floridan 

Aquifer wells at the SWSF (LS21, LS25, BOG 6-5 [also called LS32]). Analytical results from 

these wells have been presented in Figure 50. The data were gleaned from USGS and City of 

Tallahassee databases and represent analyses for NO3-N (total), NO2+NO3-N (total) and 

NO2+NO3-N (dissolved). These analyses were considered as yielding relatively equivalent 

results for the purpose of reporting this data. Historically there has been no measurable NO2 in 

the ground water of the study area and, presumptively, all detectable NO3 in ground water is 

dissolved. LS21 shows a decreasing trend with time; presently concentrations are below 1 

mg/L. LS25 and LS32 both show a rapid concentration run-up during the 1980s. 

Concentrations peaked in excess of 10 mg/L and have since declined to the 6 to 8 mg/L range. 

WWTF Residual Disposal 

In addition to effluent disposal, the City of Tallahassee also disposes of solidified wastewater 

residuals, which remain following treatment. The City of Tallahassee provided annual residual 

TN loads applied to city disposal sites (in pounds) and the area (in acres) where residuals were 

spread at each site. TN load data and disposal site acreage were provided for the period 1977 

through 2000. The annual total N load from all the City of Tallahassee’s residual facilities 

ranged from a low of 70,252 kg-N/yr in 1979 to a high of 185,851 kg-N/yr in 2000. 

In the mid-1960s, when the City of Tallahassee beginning began experimental spray application 

of wastewater effluent, spreading of wastewater residuals was also begun at the Tallahassee 

Municipal Airport. Currently, using a belt-press or screw press method, water content of the 

residuals is reduced to 18-20 percent. The solids are then spread with a manure spreader or a 

pressurized spray truck. The spreading areas (198 ha or 490 ac) at the airport are mostly 

planted in Bermuda grass, which takes up nitrogen in its growth and is subsequently harvested 

as hay. A smaller portion of the total spreading area is in planted pines (81.7 ha or 202 ac). 

The City of Tallahassee monitors five wells adjacent to the residual disposal sites at the airport. 

NO2+NO3-N concentration data from these wells are given in Figure 51, well construction details 

are summarized in Appendix A, Table A10. Concentrations in SF01, presently around 15 mg/L, 

are highest and show the greatest variability over time. SF01 is immediately adjacent to and 

south of the airport. SF05, located about 0.6 miles south of the airport shows a modest 

increasing trend, going from 0.9 mg/L in 1992 to 1.3 mg/L in 2000. SF04 also shows an 

increasing trend, 0.3 mg/L in 1993 to 0.5 mg/L in 2000. Concentrations in SF06 peaked in 1997 

and have declined since. 

In 1996, the City of Tallahassee began spreading residuals on three farms in Wakulla County as 

well (Figure 46). Recent ground water sampling at those sites yielded NO2+NO3-N 

concentrations ranging from 0.5 mg/L-N to 8.26 mg/L-N. Having no pre-spreading water quality 

data from these sites, however, it is difficult to determine how much of this N is the result of 

residual disposal and how much is the result of previous farming practices. As of 2001, the 

spreading of residuals in Wakulla County by the City of Tallahassee has been discontinued. 

According to FDEP records, the majority of the small WWTFs within the study area dispose of 

their residuals outside Leon and Wakulla counties. Their residuals go to farms near 

Wewahitchka in Gulf County. Because of a general lack of data for most of the other WWTF, 

the diversion of some of their residuals to outside the study area, and the relatively small