Numeric Nutrient Criteria 

Development for the 

Tolomato-Matanzas Estuary

Florida Department of Environmental Protection

Division of Environmental Assessment and Restoration

Joy Jackson

August 31, 2010 
Tolomato-Matanzas Estuary

Geographical and Physical Description 

 Located in St Johns and Flagler Counties. 

 Much is in the GTMNERR. Other natural areas: Guana

River Wildlife MA, Guana River, Twelve Mile Swamp 

CA, Anastasia St Park, Moses Creek CA, Matanzas St 

Forest, Faver St. Park, Pellicer Creek CA, Princess 

Place Preserve

 Land uses in the watershed are primarily upland 

forest, and wetlands; major urban area is the City of 

St. Augustine, St Augustine Beach.

 Two major inlets – St Augustine and Matanzas.
Tolomato-Matanzas Estuary

Geographical and Physical Description 

cont.

 Mean depth ~2 m

 Tidal range 1.25 m 

 Freshwater residence times 5 – 22 days

 Watershed area = 1,024 km2

 Estuary area is~44km2. 

 Ratio of watershed to estuary is 23:1.
Tolomato-Matanzas Estuary

Sources of Nutrients 

 ~80% of overall watershed is forests, wetlands, and surface 

water; ~15 % urban

 Urban stormwater, septic tanks, silviculture, agriculture, 

shoreline erosion, groundwater, and atmospheric deposition. 

 St Johns is the second fastest county in State (2000 census)

 Point source discharges (7 NPDES domestic wastewater facilities) 

Watershed Land Use
Tolomato-Matanzas Estuary

Biological Summary 

 The principle habitat types in the TME are salt marshes , 

and mollusk/oyster reefs.

 Vast stretches of nearly contiguous marsh, oyster habitat, 

and minimally developed upland strand in the TME, much 

of it publicly owned and under conservation management, 

is one reason why NOAA and the State of Florida 

established the GTMNERR. 

 The estuary supports a wide diversity of species: 358 bird, 

41 reptiles, 21 amphibian, 303 fish, and 580 plants.

 There have been minor losses to due to dredge and fill 

activities in areas around St. Augustine.
Tolomato-Matanzas Estuary

Checklist of Eutrophication Symptoms 

Response variable Observed 

historically?

Observed 

currently?

Explanation Source

Low DO (hypoxia/anoxia) Yes Yes Caused by natural factors, especially the high oxygen demand by decomposing bacteria 

in the highly organic saltmarsh systems.

Steward and Miller, pers. 

comm. 2010

Reduced clarity Yes Yes Naturally high turbidities and high tidal scouring contribute to sporadic reductions in 

clarity. The naturally low clarity (from tripton) contributes to the lack of seagrass in this 

region of Florida.

Steward et al. 2010a

Increased chlorophyll a 

concentrations

Yes No Slightly increasing temporal trend from 1986-2009 but annual averages well below the 

threshold for impairment in the IWR of 11 μg/l.

Steward et al 2010a

Phytoplankton bloom No No Short residence times, High tripton levels may help control phytoplankton densities.

Vertical mixing by tidal stirring may control phytoplankton blooms in some estuaries. 

Steward et al 2010a

Cloern 1991

Problematic epiphyte growth N/A N/A - -

Problematic macroalgal growth No No - -

SAV community changes or loss N/A N/A Large tidal amplitude and naturally high turbidity have prevented SAV establishment. Steward et al 2010a

Emergent or shoreline 

vegetation community changes 

or loss 

Yes Yes Impacts to shoreline habitats, associated with maintenance of inlets and navigation 

channels, mosquito control, and recreational boating activities, have historically 

occurred, but are spatially limited.

Haydt and Frazel 2003

Oyster reef community changes 

or loss 

Yes Yes Oyster reef communities have been negatively impacted by erosion, primarily due to 

wind and boat wakes and sediment loads due to runoff and tidal scouring.

It should be noted that denser oyster populations, with larger, meatier individuals, were 

found in areas with higher nutrient concentrations.

Haydt and Frazel 2003

Dix and Phlips 2009

Impacts to benthic community Unknown Unknown - -

Fish kills Yes Yes Fish kills reported January 2010 due to cold stress

Fish kill (red and black drum) reported August 2010 in San Sebastian Creek (St. 

Augustine, Matanzas basin); cause unknown 

FFWCC 2010
Tolomato-Matanzas Estuary

Water Quality

 Water quality in the Tolomato-Matanzas Estuary is generally good.

 Shorter residence times and greater flushing around inlets (Upper 

and Lower Matanzas River) tends to improve water quality.

Analytes Data Yrs n Data Min Median Max Range

TOLOMATO RIVER - - - - - -

total nitrogen (mg/L as N) 16 140 0.13 0.59 1.82 mid-lo

total phosphorus (mg/L as P) 16 139 0.02 0.09 1.24 mid

trichromatic uncorrected chlorophyll-a (ug/L) 16 135 0.01 5.12 27.32 mid-lo

trophic state index 16 138 -2.39 44.74 60.76 mid-lo

UPPER MATANZAS RIVER - - - - - -

total nitrogen (mg/L as N) 15 126 0.01 0.47 1.46 low

total phosphorus (mg/L as P) 15 124 0.02 0.07 0.61 mid

trichromatic uncorrected chlorophyll-a (ug/L) 15 119 0.01 4.67 23.79 mid-lo

trophic state index 15 124 -2.96 40.84 57.14 low

LOWER MATANZAS RIVER - - - - - -

total nitrogen (mg/L as N) 16 134 -0.02 0.5 1.16 low

total phosphorus (mg/L as P) 16 134 0.02 0.07 0.27 mid

trichromatic uncorrected chlorophyll-a (ug/L) 16 127 0.01 5.06 22.01 mid-lo

trophic state index 16 133 -0.85 41.8 61.71 mid-lo

Source: http://sjrwmd.com/watershedfacts/factsindex.html
Tolomato-Matanzas Estuary

Approach to criteria development

 Nutrient criteria were developed to maintain the existing conditions that 

are supportive of healthy, well-balanced populations of flora and fauna. 

 Relatively low nutrient and chlorophyll a levels, 

 Lack of long-term increasing trends in nutrient and chlorophyll a

concentrations, 

 Lack of widespread biological impacts associated with nutrients, 

 Due to this natural spatial variation, the first step in the derivation of 

appropriate nutrient criteria was to divide area into more homogeneous 

sub-regions. 
Tolomato-Matanzas Estuary

Estuary Segmentation

 Segmentation based on spatial 

analysis of TN, TP, Chla, 

salinity, turbidity, and TSI.

 Tolomato River: Palm Valley 

Bridge south to St Augustine 

Inlet

 N. Matanzas River: St. 

Augustine Inlet south to Ft 

Matanzas Inlet

 S. Matanzas River: Ft Matanzas 

Inlet south to High Bridge
0

5

10

15

20

25

30

35

40

Salinity (ppt)

Site

Salinity 

Dry Wet High Bridge Matanzas Inlet St. Augustine Inlet

Tolomato

median: 31.9 ppt

1986 – 2009 period of record

N. Matanzas

median: 33.5 ppt

S. Matanzas

median: 31.5 ppt

0

2

4

6

8

10

12

14

16

18

Turbidity (ntu)

Site

Turbidity Dry Wet

High 

Bridge

Matanzas

Inlet

St. Augustine 

Inlet

Palm Valley 

Bridge

S. Matanzas

median: 7.8 ntu

N. Matanzas

median: 7.5 ntu

Tolomato

median: 9.4 ntu

Tidal 

node 

point

Tolomato-Matanzas Estuary
Spatial distribution of TN, TP, and Chl-a (μg/L) means and medians 

1986-2009 

0

2

4

6

8

10

12

14

16

CHLAC μg/l)

Site

Chlorophyll a (corrected) Dry Wet

0

0.05

0.1

0.15

0.2

0.25

0.3

TP (mg/l)

Site

Total Phosphorus Dry Wet

High Bridge

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

TN (mg/l)

Site

Total Nitrogen DRY Wet

Palm Valley

Bridge

Matanzas Inlet St. Augustine 

Inlet High Bridge

S. Matanzas

median: 0.49 mg/L

mean: 0.50 mg/L

N. Matanzas

median: 0.41 mg/L

mean: 0.43 mg/L

Tolomato

median: 0.53 mg/L

mean: 0.58 mg/L

S. Matanzas

median: 0.083 mg/L

mean: 0.10 mg/L

N. Matanzas

median: 0.072 mg/L

mean: 0.087 mg/L

Tolomato

median: 0.084 mg/L

mean: 0.098 mg/L

S. Matanzas

median: 3.9 mg/L

mean: 4.6 mg/L

N. Matanzas

median: 3.1 mg/L

mean: 3.4 mg/L

Tolomato

median: 4.3 mg/L

mean: 5.0 mg/L

Mean ± s.d.

Mean ± s.d.

Mean ± s.d.

Tidal 

node 

point
Tolomato-Matanzas Estuary

Approach to criteria development 

cont. - Multiple Lines of Evidence

 Reference Period

 Chl a – TN & TP Regression Models

 General Models 

 Geometric Means
Tolomato-Matanzas Estuary

Reference Period

 Good spatial and temporal coverage; supports 

good trophic state (<50 TSI), healthy aquatic life, 

fully supports designated use.

 At least 5 consecutive years or longer to avoid bias 

from extreme events (e.g., drought, hurricanes).

 Data from 2000-2009 was considered most 

temporally and spatially complete and subject to 

less bias from episodic events.

Segment Chla (μg/L) TN (mg/L) TP (mg/L)

Tolomato 4.5 (5.3) 0.52 (0.56) 0.085 (0.096)

N. Matanzas 3.1 (3.5) 0.37 (0.41) 0.073 (0.083)

S. Matanzas 4.3 (5.0) 0.45 (0.49) 0.089 (0.103)

Tolomato-Matanzas Estuary, reference period results–1st line of evidence: Annual median (mean),
Tolomato-Matanzas Estuary

Chla-TN, TP Regressions

 All data from full period is organized into annual 

averages, monthly averages, and avg. wet season 

monthly data sets.

 If model had strong correlation and significance, it was 

used to predict median concentrations based on 

reference period Chla medians.

Segment Target Chla 

(μg/L)

TN 

(mg/L)

r p TP 

(mg/L)

r p

Tolomato 6.4 0.62 0.63 .028 0.110 0.68 .014

N. Matanzas 4.0 0.46 0.72 .008 0.095 0.81 .002

S. Matanzas 6.3 0.61 0.87 .0002 0.120 0.82 .001

Tolomato-Matanzas Estuary, linear regression results–2nd line of evidence: Maximum wetseason median (1986–2009; all months). 
Tolomato-Matanzas Estuary

General Models

 Steward and Lowe 2010

 Uses relationship between 

hydraulic loading (mean 

depth/water residence 

times) and nutrient loading 

limits for mesotrophic

Florida systems.

 Dettmann 2001

 Predicts TN based on 

trophically desirable TN 

loading limit.

S. Matanzas

Tolomato

-0.5

0.5

1

1.5

2

2.5

-0.5 0 0.5 1 1.5 2 2.5 3

log qs (z/τw; m/yr)

log TN load limit (g/m2/yr)

95% upper CI

LML

N. Matanzas

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

-0.5 0.0 0.5 1.0 2.0 2.5 3.0

log qs (z/τw; m/yr)

log TP load limit (g/m2/yr)

N. Matanzas

S. Matanzas

Tolomato

2.0

95% upper CI

LML

TN 

TP
Tolomato-Matanzas Estuary

Numeric Nutrient and Chlorophyll Recommendations: 

Concentrations and Loads 

Segment Chla (μg/L) TN (mg/L) TP (mg/L)

Tolomato segment 4.5 (5.3) 0.52 (0.56) 0.085 (0.096)

N. Matanzas segment 3.1 (3.5) 0.37 (0.41) 0.073 (0.083)

S. Matanzas segment 4.3 (5.0) 0.45 (0.49) 0.089 (0.103)

Tolomato-Matanzas Estuary, concentration limits: Annual median (mean), 2000–09. 

Segment TN: kg/yr TP: kg/yr 

Tolomato segment 76,727 11,264 

N. Matanzas segment 237,074 43,792 

S. Matanzas segment 208,025 37,142 

Tolomato-Matanzas Estuary loading limits (ca. 2004 loadings) for TN and TP.
Segment TN: kg/yr TP: kg/yr 

Tolomato segment 76,727 11,264 

N. Matanzas segment 237,074 43,792 

S. Matanzas segment 208,025 37,142 

Tolomato-Matanzas Estuary loading limits (ca. 2004 loadings) for TN and TP

Tolomato-Matanzas Estuary

Numeric Nutrient and Chlorophyll Recommendations: Loads 
FDEP Total Phosphorus (μg/L)

Segment

Existing Long 

Term 

Geometric 

Mean 

Maximum Allowed 

Long term 

Geometric Mean

Annual Geometric Mean for a 

Network of Stations (2 of 5 

year exceedance rate)

Annual Geometric Mean for 

a Single Site (2 of 5 year 

exceedance rate)

N. Matanzas 0.074 0.082 0.102 0.109

S. Matanzas 0.092 0.101 0.119 0.120

Tolomato 0.087 0.096 0.116 0.119

FDEP Total Nitrogen (mg/L)

Segment

Existing Long 

Term 

Geometric 

Mean 

Maximum 

Allowed Long 

term Geometric 

Mean

Annual Geometric Mean 

for a Network of Stations 

(2 of 5 year exceedance 

rate)

Annual Geometric Mean 

for a Single Site (2 of 5 

year exceedance rate)

N. Matanzas 0.382 0.420 0.493 0.501

S. Matanzas 0.445 0.489 0.540 0.556

Tolomato 0.528 0.581 0.662 0.681

FDEP Chlorophyl a (mg/L)

Segment

Existing Long 

Term 

Geometric 

Mean 

Maximum 

Allowed Long 

term Geometric 

Mean

Annual Geometric Mean 

for a Network of Stations 

(2 of 5 year exceedance

rate)

Annual Geometric Mean 

for a Single Site (2 of 5 

year exceedance rate)

N. Matanzas 2.95 3.24 4.03 4.18

S. Matanzas 3.96 4.35 5.87 6.06

Tolomato 4.19 4.60 6.05 6.15

Tolomato-MatanzasEstuary

Numeric Nutrient and Chlorophyll Recommendations: 

Annual Geometric Means 
Tolomato-Matanzas Estuary

SUMMARY 

 There is considerable evidence to demonstrate that the 

nutrient regime in the Tolomato-Matanzas Estuary is not 

adversely affecting the biological communities. A reduction in 

nutrients would not lead to recovery of oysters or tidal 

marshes, or improve the condition of other biological 

resources in the bay. 

 FDEP therefore proposes nutrient concentration targets that 

reflect the current conditions as reported from 2000 to 2009 

water quality monitoring data.
Tolomato-Matanzas Estuary

Next Steps

• Provide additional comments on estuary report to: 

Joy Jackson

• Phone 850-245-8074

• Email: Joy.Jackson@dep.state.fl.us

• Finalize estuary reports.

• Information concerning nutrient criteria development posted to 

DEP website: http://www.dep.state.fl.us/water/wqssp/nutrients/estuarine.htm