Site-Specific Information 

in Support of Establishing 

Numeric Nutrient Criteria in 

St. Joseph Sound and 

Clearwater Harbor

Division of Environmental Assessment and Restoration

Standards and Assessment Section

Florida Department of Environmental Protection

Tallahassee, FL 32399

August 25, 2010 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft ii August 2010

Table of Contents

Executive Summary ............................................................................................................... 1

Geographic and Physical Description ..................................................................................... 3

Sources of Nutrients.............................................................................................................. 7

Biological Summary............................................................................................................. 10

Submersed Aquatic Vegetation ................................................................................................. 10

Epiphyte Loads on Seagrass ......................................................................................................16

Phytoplankton Species Composition and Chlorophyll a...............................................................16

Macroalgal Species Composition and Biomass...........................................................................17

Depth to Seagrass Targets ........................................................................................................18

Presence and Frequency of Harmful Algal Blooms......................................................................18

Coral or Hard Bottom Community Structure and Areal Extent ....................................................18

Shellfish Production and Frequency/Duration of Bed Closures....................................................18

Quantification of Landings from Commercial/Recreational Fisheries..........................................19

Existing Local Biological Indices................................................................................................. 23

HABs, Fish Kills..........................................................................................................................23

Hypoxia....................................................................................................................................23

Other Biological Resources........................................................................................................23

Water Quality Studies ......................................................................................................... 23

Existing Regional Nutrient Loading Models................................................................................29

Estuary Segments on 303(d) Impaired Waters List .....................................................................29

Numeric Nutrient Criteria Recommendations ...................................................................... 38

References .......................................................................................................................... 39
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft iii August 2010

List of Tables

Table 1a. Checklist of nutrient enrichment symptoms.................................................................................. 2

Table 1b. Checklist of additional factors...................................................................................................... 3

Table 2a. Geographic and land use information for St. Joseph Sound (SJS), Clearwater Harbor 

(CWH), and Boca Ciega Bay (BCB)................................................................................................. 5

Table 2b. Detailed land use breakdown for St. Joseph Sound (SJS). ............................................................ 6

Table 2c. Detailed land use breakdown for Clearwater Harbor (CWH). ...................................................... 6

Table 3. Median/mean values for sampling strata in western Pinellas County from 2004-2008. 

Strata as in Figure 1 (from Levy et al. 2009, Appendix A). ..........................................................24

Table 4. Maximum/minimum values for sampling strata in Western Pinellas County from 2004-

2008. Strata as in Figure 1 (from Levy et al. 2009, Appendix A). ................................................24

Table 5. Verified impaired waterbodies that empty into St. Joseph Sound, Clearwater Harbor, or 

Northern Boca Ciega Bay. ...........................................................................................................34

List of Figures

Figure 1. Open water assessment segments within Pinellas County. Strata W1-W8 are discussed 

in this report. (Figure 5 from Levy et al. 2009)............................................................................. 4

Figure 2. Location of major watersheds contributing to Clearwater Harbor North and South and 

St. Joseph Sound within Pinellas County, Florida (from Levy 2010). ............................................. 8

Figure 3. Annual freshwater flow into Clearwater Harbor and St. Joseph Sound (from Levy 2010)............ 9

Figure 4. Annual loading of total phosphorus from tributaries to Clearwater Harbor and St. 

Joseph Sound, 2003-2008 (from Levy 2010).................................................................................. 9

Figure 5. Annual loading of total nitrogen from tributaries to Clearwater Harbor and St. Joseph 

Sound, 2003-2008 (from Levy 2010). ..........................................................................................10

Figure 6. Mapped submersed aquatic vegetation (SAV) coverage in St. Joseph Sound for 2008 

(data provided by SWFMWD)......................................................................................................12

Figure 7. Mapped SAV coverage in Clearwater Harbor for 2008 (data provided by SWFMWD)...............13

Figure 8. Mapped SAV coverage in Boca Ciega Bay for 2008 (data provided by SWFMWD)....................14

Figure 9. Spatial representation of the SAV species mean abundance per transect from two years 

of stratified random sampling in St. Joseph Sound and Clearwater Harbor (Figure 10 

from Meyer and Levy 2008). .......................................................................................................15

Figure 10. Spatial representation of SAV health, epibiont density, sediment type, and depth for 

seagrass transects from two years of stratified random sampling in St. Joseph Sound 

and Clearwater Harbor (Figure 14 from Meyer and Levy 2008). ................................................16

Figure 11. Mean abundance of marine algae and the presence of scallops per transect from two 

years of stratified random sampling in St. Joseph Sound and Clearwater Harbor (Figure 

11 from Meyer and Levy 2008)....................................................................................................17

Figure 12. Average charter angler pressure per day for St. Joseph Sound and Clearwater Harbor. 

Data from angler survey by FWCC, and maps made by Janicki Environmental, Inc. ..................20
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft iv August 2010

Figure 13. Average private boat angler pressure per day for St. Joseph Sound and Clearwater 

Harbor. Data from angler survey by FWCC, and maps made by Janicki Environmental, 

Inc. ...............................................................................................................................................21

Figure 14. Average shore angler pressure per day for St. Joseph Sound and Clearwater Harbor. 

Data from angler survey by FWCC, and maps made by Janicki Environmental, Inc. ..................22

Figure 15. Pinellas County bottom dissolved oxygen (mg/L) interpolation map applying kriging 

using 2004-2008 data (Figure 10c in Levy et al. 2009)...............................................................25

Figure 16. Pinellas County chlorophyll-a (μg/L) interpolation map applying inverse distance 

weighting using 2004-2008 data (Figure 9c in Levy et al. 2009).................................................26

Figure 17. Pinellas County transmissivity % (at 660 nm) interpolation map applying kriging using 

2004-2008 data (Figure 8c in Levy et al. 2009). ..........................................................................27

Figure 18. Mean chlorophyll a and TN/TP ratios for St. Joseph Sound from 2003-2008 (from Levy 

2010). ..........................................................................................................................................28

Figure 19. Mean chlorophyll a and TN/TP ratios for North Clearwater Harbor from 1992-2008 

(from Levy 2010)..........................................................................................................................28

Figure 20. Mean chlorophyll a and TN/TP ratios for South Clearwater Harbor from 1992-2008 

(from Levy 2010)..........................................................................................................................29

Figure 21. Pinellas County waters impaired for chlorophyll a and Trophic State Index (lakes) 

based on FDEP 2009 verified lists and the 1998 303(d) list for Group 1 and Group 5 

basins (Figure 3 in Levy et al. 2009). ...........................................................................................31

Figure 22. Pinellas County waters impaired for DO based on FDEP 2009 verified lists and the 

1998 303(d) list for Group 1 and Group 5 basins (Figure 2 in Levy et al. 2009). .........................32

Figure 23. Pinellas County waters impaired for bacteria based on FDEP 2009 Verified Lists and 

the 1998 303(d) list for Group 1 and Group 5 basins (Figure 4 in Levy et al. 2009)....................33
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 1 August 2010

Executive Summary

This report was prepared by the Florida Department of Environmental Protection (FDEP), in cooperation 

with the Pinellas County Department of Environmental Management,

1

Submersed aquatic vegetation (SAV), including seagrass and macroalgae, is the most nutrient sensitive 

biological endpoint in St. Joseph Sound, Clearwater Harbor, and Boca Ciega Bay, and extensive water 

quality and seagrass data exist for the system since 1992 (since 1950 for seagrass in Boca Ciega Bay). 

The portion of Pinellas County that borders these estuaries is heavily urbanized, and there were historic 

impacts on water quality and SAV. Impacts from urbanization have been mitigated in recent decades, 

and water clarity is generally good and SAV coverage is extensive in these areas. St. Joseph Sound has 

lower chlorophyll a and a greater percentage of SAV coverage than Clearwater Harbor or Boca Ciega 

Bay, portions of which are on the 303(d) list for chlorophyll a. The impaired portions of Clearwater 

Harbor and Boca Ciega Bay have longer residence times and less contact with the Gulf of Mexico than 

the other portions of this region, which would contribute to higher chlorophyll a in those areas, even in 

the absence of urban influence. Chlorophyll a concentrations have declined in the past two decades in 

the entire region, and SAV coverage has increased during that time, likely due to nutrient control 

measures employed by county and city government in this region. Based on the information gathered 

here, aquatic life use is being fully supported in St. Joseph Sound, northern Clearwater Harbor, and 

southern Boca Ciega Bay, and efforts are underway to attain fully supported aquatic life use in southern 

Clearwater Harbor and northern Boca Ciega Bay. 

to support the development of 

site specific numeric nutrient criteria for St. Joseph Sound, Clearwater Harbor, and Boca Ciega Bay. The 

primary purpose of the proposed numeric nutrient criteria is to protect healthy well-balanced natural 

populations of flora and fauna from the effects of excess nutrient enrichment. 

Pinellas County has hired Janicki Environmental consulting firm to develop nutrient and transparency 

targets for St. Joseph Sound and Clearwater Harbor. That work is being overseen by the Clearwater 

Harbor/St. Joseph Sound Comprehensive Conservation Management Plan (CCMP) Working Group. The 

anticipated completion date for the nutrient and transparency targets is late 2010. FDEP does not plan 

to propose numeric nutrient criteria for these regions until their work is complete. Nutrient loading 

targets have been set for southern Boca Ciega Bay as part of the Tampa Bay Nitrogen Management 

Consortium, and FDEP supports those recommendations. FDEP proposes that the chlorophyll a target 

for Lower Tampa Bay (5.1 μg/L) be adopted for lower Boca Ciega Bay. Once Janicki Environmental, Inc., 

has completed work on southern Clearwater Harbor, FDEP will consider if the proposed criteria for that 

segment would also be appropriate for northern Boca Ciega Bay. FDEP will continue to work with the 

Pinellas County Department of Environmental Management and the Tampa Bay Estuary Program to 

develop numeric nutrient criteria for this region. 

 

1 Contributors to this report include Kelli Levy (Pinellas County Department of Environmental Management) and Kris Kaufman (Southwest 

Florida Water Management District (SWFWMD).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 2 August 2010

Table 1a. Checklist of nutrient enrichment symptoms. - = Empty cell/no data

Response variable Observed 

historically?

Observed 

currently?

Explanation Source

Low DO 

(hypoxia/anoxia)

Yes Yes Some tidal creeks are on the 303(d) list for 

DO. In open waters, some areas have 

bottom DO below 4 mg/L during warm 

months.

303(d) list, Levy 

2010

Reduced clarity Yes No SAV loss from 1950 to 1982 likely due to 

reduced clarity, but acreage has been 

increasing for past 20 years.

SWFWMD 

Increased 

chlorophyll a

concentrations

Yes No Historical loss of SAV likely related to 

chlorophyll a; however concentrations have 

decreased or remained constant since 

1992.

Levy 2010

Phytoplankton 

blooms (nuisance 

or toxic)

Yes Yes Red tide (Karenia brevis blooms) is 

common in this part of the coast.

- 

Problematic 

epiphyte growth 

No No Epiphyte loads vary throughout the region, 

but have not been related to nutrient levels 

or considered problematic

Meyer and Levy 

2008

Problematic 

macroalgal growth

No No Macroalgae are a major component of the 

submersed aquatic community, but not 

considered problematic.

Meyer and Levy 

2008

SAV community 

changes or loss

Yes No Over 50% of SAV was lost in BCB from 1950 

to 1982, and some loss likely occurred in 

CLW. SAV coverage in BCB rebounded to 

80% former coverage in 2008. SAV 

coverage increased 16% between 1999 and 

2008 in SJS and CLW. Loss occurred on all 

areas due to dredging and filling as part of 

the development of Pinellas County, and 

that loss is considered permanent and not 

related to nutrients or water clarity. 

Kelli Levy, Pinellas 

County Dept. 

Environmental 

Management, 

personal 

communication; 

SWFWMD SAV 

data

Emergent or 

shoreline 

vegetation 

community 

changes or loss 

Yes - Much of the mainland shoreline has been 

developed, so there are many seawalls and 

little intact shoreline vegetation. Analysis 

ongoing by Janicki Environmental, Inc.

- 

Coral/hardbottom 

community 

changes or loss 

Unknown? - There is some hardbottom community in 

this area, but it has not been studied. 

- 

Impacts to benthic 

community

Unknown? - - - 

Fish kills Yes, limited 

in space and 

time

- Periodic fish kills have occurred as a result 

of red tide blooms and cold-water induced 

shock; however, no significant kills have 

been reported as a direct result of nutrient 

inputs into the estuary.

- 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 3 August 2010

Table 1b. Checklist of additional factors. - = Empty cell/no dat

Nutrient Factors Observed? Explanation Source

Increased nutrient loading 

or concentrations

No Historic increases, but nutrient loading 

from humans has decreased in the past 

ten years 

Levy 2010

Difference between 

nearshore and offshore 

levels 

Unknown No data available for coastal area outside 

barrier islands.

- 

Mitigating factors that 

could prevent nutrient 

expression

No - - 

Other significant stressors 

to biological communities

No - - 

Natural high nutrient 

episodes (e.g., seasonal or 

event driven)

No - - 

 

Geographic and Physical Description

St. Joseph Sound, Clearwater Harbor, and Boca Ciega Bay are in western Pinellas County along the Gulf 

side of the cities of St. Petersburg, Largo, Clearwater, Dunedin, and Tarpon Springs. All three areas are 

constricted to varying degrees by barrier islands (Figure 1). St. Joseph Sound is well mixed with the Gulf 

of Mexico, Clearwater Harbor is fairly well flushed in the northern end, but less so in the southern 

portion, and Boca Ciega Bay has limited contact with the Gulf. In Clearwater Harbor, water exchanges 

with the Gulf of Mexico through Clearwater Pass (north end of Southern half) and Hurricane Pass (north 

end of Northern half); Dunedin Pass (middle of Northern half) has been closed. Boca Ciega Bay 

exchanges with the Gulf of Mexico through several limited passes. These estuarine areas are part of the 

Pinellas County Aquatic Preserve, and much of the barrier island area bordering St. Joseph Sound is 

preserved as state parks (Anclote Key Preserve State Park, Honeymoon Island State Park, and Caladesi 

Island State Park). Physical information about these estuarine areas is provided in Table 2a. 

Pinellas County is 96% developed, with more natural areas in the northern portion of the county than 

the southern (Table 2). Barrier islands along the western boundary of Clearwater Harbor and Boca Ciega 

Bay have been physically modified for development by dredging and filling to create finger canals and 

extend the land for development. The Pinellas County Department of Environmental Management 

(PCDEM) conducted a forum in March 2007, in which various stakeholders presented information about 

the region’s history and resources, and there is a wealth of information from that meeting posted on the 

PCDEM website (available: 

http://www.pinellascounty.org/Environment/pagesHTML/watershedMngmt/wm8000.html).

Janicki Environmental, Inc. submitted a proposal to Pinellas County for the development of a 

comprehensive conservation management plan (CCMP) for Clearwater Harbor and St. Joseph Sound 

(Janicki 2009). That proposal was funded, contains a rich description of the study area, and is available 

on the Pinellas County Water Atlas website. That project is ongoing and will produce nutrient and 

chlorophyll a targets for this region (see: 

http://www.pinellas.wateratlas.usf.edu/news/committees.asp?GROUPID=10050&ACTIVE=1).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 1. Open water assessment segments within Pinellas County. Strata W1-W8 are discussed in 

this report. (Figure 5 from Levy et al. 2009)
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Table 2a. Geographic and land use information for St. Joseph Sound (SJS), Clearwater Harbor (CWH), 

and Boca Ciega Bay (BCB). 

Note: Most information is not yet complete for Boca Ciega Bay.

- = Empty cell/no data

Information Category Available Data Values Source

Estuarine surface area 

(km2

) 

- SJS- 18,000 acres

CWH- 10,000 acres

Janicki 2009

Watershed area (km2) Pinellas County 

Basin Shapefile

SJS- 19,000 acres

CWH- 27,000 acres

Janicki 2009

Land use SWFWMD 

Land Use 

Shapefile

SJS-(see Table 2b for a detailed breakdown of land uses)

CWH-(see Table 2c for a detailed breakdown of land uses)

Southwest 

Florida Water 

Management 

District

Mean depth (m) NGDC Center 

Coastal Relief 

Model Clip 

Shapefile 

SJS-1.49 m 

CWH-1.20 m

Florida Shelf 

Habitat 

(FLASH map 

Project , USGS 

2007) 

Volume (m3) NGDC Center 

Coastal Relief 

Model

Mean High water volume:

SJS- 79,803,504 m3

CWH- 44,389,219 m3

Mean Low Water volume:

SJS-43,388,254 m3

CWH- 23,103,029 m3

Florida Shelf 

Habitat 

(FLASH map 

Project , USGS 

2007) 

Tidal range (m) Pinellas County 

Tidal Ranges

SJS- 0.369m Above Sea Level (ASL) to 0.210m Below Sea 

Level (BSL)

CWH- 0.357 ASL to 0.192 BSL

Tidal freshwater inflow 

(1000 m3

d-1) 

2004-2008 

Flow Data 

SJS- 2090.765 (in 1000 m3d-1) (includes Smith Bayou and 

Klosterman Bayou)

CWH- 22963.81 (in 1000 m3d-1) (includes Cedar Creek, 

Curlew Creek, Spring Branch, Coastal Zones 1 and 4, and 

McKay Creek)

Levy et al. 

2008

Mean water residence 

time (days)

No information currently exists. This should be developed in 

the CCMP for St. Joseph Sound and Clearwater Harbor.

- 

Salinity and salinity 

zones

Salinity 2004-

2008

SJS- Mean: 32.37 PPT; Range: 22.9-38.4 PPT

CWH- Mean: 33.73 PPT; Range 25.1-38.4 PPT

Levy et al. 

2008

Transparency/optical 

data

TSS, Turbidity, 

Transmissivity 

2004-2008

data in STORET and Water Atlas, summarized in Appendix A 

of Levy et al. 2009 

Levy et al. 

2009 

Nutrient data Chl a, 2004-

2008

data in STORET and Water Atlas, summarized in Appendix A 

of Levy et al. 2009 

Levy et al. 

2009 

Meter data (DO, 

temperature, salinity, 

pH)

Surface and 

Bottom 

readings for all 

sampling 

stations 2004-

2008

data in STORET and Water Atlas, summarized in Appendix A 

of Levy et al. 2009 

Levy et al. 

2009 

Annual and Seasonal 

Loading of TN and TP

Load estimates 

for 2004-2008 

for each 

subwatershed

SJS- Annual Loads: TN: 5.43 Tons/Year; TP: 1.59 Tons/Year 

(includes Smith Bayou and Klosterman Bayou)

CWH- Annual Loads: TN: 39.62 Tons/Year; TP: 5.88 

Tons/Year (includes Cedar Creek, Curlew Creek, Spring 

Levy et al. 

2009 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Information Category Available Data Values Source

Branch, Coastal Zones 1 and 4, and McKay Creek)

GIS interpolation maps Salinity, 

Bottom DO, 

Chlorophyll-a, 

Transmissivity 

2004-2008

data in STORET, summarized in Appendix A of Levy et al. 

2009 

Levy et al. 

2009 

Drainage system GIS files Asset management databases of contributing drainage 

systems

Pinellas 

County, 

Tarpon 

Springs, 

Clearwater, 

Dunedin, 

Largo

Table 2b. Detailed land use breakdown for St. Joseph Sound (SJS). - = Empty cell/no data

Land Use Type Acreage Percent

Agriculture 11645481 11.82%

Commercial 6234270 6.33%

Natural 19875244 20.18%

Open/Disturbed Lands 4290692 4.36%

Recreational 5175804 5.25%

Reservoirs 1435166 1.46%

Residential 44794485 45.47%

Transportation 4301079 4.37%

Utilities 757463 0.77%

Table 2c. Detailed land use breakdown for Clearwater Harbor (CWH). - = Empty cell/no data

Land Use Type Acreage Percent

Agriculture 436497 0.28%

Commercial 16532290 10.70%

Natural 4785361 3.10%

Open Land 1200600 0.78%

Recreational 7875260 5.10%

Reservoirs 2177998 1.41%

Residential 103587061 67.02%

Transportation 16845320 10.90%

Utilities 1121041 0.73%
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Sources of Nutrients 

Pinellas County forms the landward border of these estuary areas. It is a densely populated urban area 

in which environmental resource managers have made efforts to reduce loading of nutrients to these 

estuaries as well as to Tampa Bay to the east. There are eight watersheds that contribute fresh water to 

St. Joseph Sound and Clearwater Harbor (Figure 2), and freshwater flow varies by year and by watershed 

(Figure 3). All wastewater treatment plants use advanced treatment (AWT) in Pinellas County, and 

much of the wastewater is converted into reuse water for watering lands. The whole county is hooked 

up to sanitary sewer systems, so there are minimal inputs from septic tanks. The conversion to AWT has 

reduced nutrient loading in the past ten years. A new county fertilizer ordinance should reduce inputs 

of nutrients from urban stormwater sources. Pet waste is considered a large source of fecal coliform 

bacteria in some sub-watersheds (Albright 2008, Kurisko 2008), so that may be a source of nutrients as 

well. Pinellas County and municipalities within the county have conducted numerous stormwater 

retrofit projects within the county. Loadings of total nitrogen (TN) and total phosphorus (TP) to St. 

Joseph Sound and Clearwater Harbor declined from 2003 to 2008 in most contributing basins (Figures 4 

and 5; Levy 2010). 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 2. Location of major watersheds contributing to Clearwater Harbor North and South and St. 

Joseph Sound within Pinellas County, Florida (from Levy 2010). 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 3. Annual freshwater flow into Clearwater Harbor and St. Joseph Sound (from Levy 2010). 

Figure 4. Annual loading of total phosphorus from tributaries to Clearwater Harbor and St. Joseph 

Sound, 2003-2008 (from Levy 2010).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 10 August 2010

Figure 5. Annual loading of total nitrogen from tributaries to Clearwater Harbor and St. Joseph Sound, 

2003-2008 (from Levy 2010).

Biological Summary

Submersed Aquatic Vegetation

Submersed Aquatic Vegetation (SAV), which consists of seagrass and macroalgae, is abundant in these 

bays and is the most sensitive ecological endpoint. Halodule wrightii is abundant and distributed 

throughout the region. Thalassia testudinum is abundant in St. Joseph Sound and Clearwater Harbor, 

but not as abundant in Boca Ciega Bay. Syringodium filiforme is abundant in St. Joseph Sound, but 

present in lower numbers in Clearwater Harbor and Boca Ciega Bay. St. Joseph Sound (SJS) contains the 

greatest coverage of SAV, followed by Clearwater Harbor (CLW) and Boca Ciega Bay (BCB). Clearwater 

Harbor and Boca Ciega Bay contains significant areas which can no longer be colonized by SAV due to 

dredge and fill operations (Kelli Levy, PCDEM, personal communication). 

The Southwest Florida Water Management District (SWFWMD) performed aerial mapping of Clearwater 

Harbor and St. Joseph Sound in 1999, 2002, 2004, 2006, and 2008 (resolution of 0.5 acres and 80% 

ground-truthing accuracy, map is of SAV which includes macroalgae). Surveys were first conducted for 

Boca Ciega Bay in 1988, and were done for nearly every two years since then. The first SAV estimate 

(1999) was 13,994 acres, and 17,422 acres seagrass was estimated for 2008, for a 16% increase

(PCDEM). In 2008, there were 12,639 acres of SAV in St. Joseph Sound (Figure 6), 3,784 acres in 

Clearwater Harbor North (Figure 7), and 1,000 acres in Clearwater Harbor South (Figure 7; data from 

SWFWMD). 

Estimates of SAV acreage are available for Boca Ciega Bay (BCB) from 1950, 1982, and then nearly every 

two years from 1988 to 2008. There were 10,800 acres of SAV in BCB in 1950. The area of SAV then 

declined to 5,770 acres in 1982, but has been steadily increasing ever since, and totaled 8,457 acres in 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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2008 (Figure 8; data from SWFWMD). That expansion was evident in data collected along fixed 

transects by the Tampa Bay Estuary Program in BCB from 1998-2009 (Avery et al. 2010 Appendix B).

Meyer and Levy (2008) summarized results from PCDEM seagrass monitoring from 1998-2007, and 

reported that seagrasses are stable. The PCDEM sampled fixed transects in SJS, CLW, and BCB from 

1998-2005, and have employed a stratified random sampling design in SJS and CWH from 2006-present. 

During fixed transect sampling, the following information was collected: Braun-Blanquet seagrass % 

cover, water depth, sediment composition, seagrass condition and algae occurrence. The sediment 

composition is qualitatively categorized as sand, sandy mud, mud, shelly mud, shelly sand, or hard 

bottom. The seagrass condition is qualitatively categorized as very good, good, fair, poor, or necrotic. 

Epibiont density on the seagrass blade was assessed using a numerical rating scale: 1= clean, 2= light 

coverage, 3= moderate, 4= heavy. At the transect’s mid-bed and edge of bed, staff recorded shoot 

density and canopy height. Three density counts were made using either a 10x10cm or 25x25cm square 

frame. Also, five shoot lengths were recorded to the nearest centimeter. Samplers assess each species 

independently. Chlorophyll-a, turbidity, Hydrolab®, and LICOR® readings were taken at mid-bed, edge of 

bed, and the 2m depth contour. 

In their report of fixed transect SAV monitoring from 1998-2005, Meyer and Levy (2008) reported that 

seagrass abundance and density remained relatively stable in all areas during the study period, although 

there were some localized changes in bed length or shoot density. Most changes were increases in bed 

length or seagrass abundance, but there were some decreases in 2004-2005 that they attributed to 

hurricanes (Meyer and Levy 2008). 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 6. Mapped submersed aquatic vegetation (SAV) coverage in St. Joseph Sound for 2008 (data 

provided by SWFMWD). 

SAV data from the first two years of stratified random sampling were compared among strata (CLW = 

Clearwater Harbor North and South, SJS = St. Joseph Sound) and depth categories (A = 0-0.6m, B = 0.6-

1.2m, and C = >1.2m) in Meyer and Levy (2008). SAV covered most of the study area, but mean 

abundance was greatest in STJS and least in CLWS. Mean abundance in depth zone A was 77%, 

significantly higher than the mean for zone C, 37% (Meyer and Levy 2008). The three main species of 

seagrass were distributed throughout the study area, but Syringodium was significantly less abundant in 

CLWS and CLWN than in STJS (Figure 9). Syringodium also had significantly greater abundance in depth 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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zone B (19%), than in zone A (7%), which probably explains its greater abundance in deeper STJS. 

Thalassia abundance was significantly greater in zone A (35%) than in B (14%) or C (6%). Halodule was 

distributed throughout the region, mainly in depth zones A and B, with highest abundance in CLWN and 

least in STJS (Figure 9; Meyer and Levy 2008). Seagrass health was typically good or fair throughout the 

study area, with no clear pattern between strata (Figure 10). Epibiont density was greatest in STJS and 

in depth zone B (Meyer and Levy 2008). Upon visual inspection of the data, CLWS had more transects 

with mud substrate (Figure 10). 

Figure 7. Mapped SAV coverage in Clearwater Harbor for 2008 (data provided by SWFMWD). 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 8. Mapped SAV coverage in Boca Ciega Bay for 2008 (data provided by SWFMWD). 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 9. Spatial representation of the SAV species mean abundance per transect from two years of 

stratified random sampling in St. Joseph Sound and Clearwater Harbor (Figure 10 from Meyer and 

Levy 2008).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 10. Spatial representation of SAV health, epibiont density, sediment type, and depth for 

seagrass transects from two years of stratified random sampling in St. Joseph Sound and Clearwater 

Harbor (Figure 14 from Meyer and Levy 2008).

Epiphyte Loads on Seagrass

Epiphyte ranks (measured as epibiont with other attached organisms) varied widely from light to heavy 

coverage in SJS and CLW in the PCDEM SAV sampling, with most rated as light or moderate, and there 

was no distinct regional distribution of epiphytes (Figure 10; Meyer and Levy 2008). They appear to 

have greater densities on Halodule but still no geographic trend, based on 2007 to 2009 seagrass data 

trends (PCDEM unpublished data).

Phytoplankton Species Composition and Chlorophyll a 

The mean (and range) chlorophyll a concentrations from 2004-2007 for Clearwater Harbor South, 

Clearwater Harbor North, and St. Joseph Sound were 5.0 μg/L (0.3-17.2), 3.9 μg/L ( 0.3-13.3), and 2.3 

μg/L (0.3-18.9), respectively. Two studies of the Anclote Anchorage (area offshore from the Anclote 

River) from 1975 showed that diatoms were the major component of the marine phytoplankton, with 

occasional occurrence of dinoflagellates (Johansson 1975, Hamm 1975). 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Macroalgal Species Composition and Biomass 

Data collected during 2008 and 2009 seagrass surveys performed in SJS and CLW by PCDEM show that 

macroalgae species were present in 61% (48 out of 78) of the sample sites in St. Joseph Sound, while in 

Clearwater Harbor macroalgae species were found in 37% (20 out of 54) of the sample sites (PCDEM 

unpublished data). Various species of marine algae were found, including a minimum of ten attached 

algae and four species of Caulerpa (Levy et al. 2008). Rhizophytic algae, including Caulerpa prolifera, 

were generally restricted to St. Joseph Sound in 2006-2007 (Figure 11; Meyer and Levy 2008).

Figure 11. Mean abundance of marine algae and the presence of scallops per transect from two years 

of stratified random sampling in St. Joseph Sound and Clearwater Harbor (Figure 11 from Meyer and 

Levy 2008).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Depth to Seagrass Targets

No depth targets have yet been established, but random sampling data shows that Halodule and 

Syringodium colonize depths greater than 2m in SJS and CLW (Figures 9 and 10; Meyer and Levy 2008).

Presence and Frequency of Harmful Algal Blooms

Red Tide (Karenia brevis) occurs frequently in this area. Since 2004 it has been found in JanuaryFebruary 2004, February-March 2005, June-October 2005, September-October 2006, and October 2008. 

Densities have varied from 1,000 to >1,000,000 cells/L during these blooms (PCDEM). Anecdotal 

accounts of Red Tide in this area date back to 1844. (FWRI historical data available: 

http://research.myfwc.com/features/category_main.asp?id=2037) 

The causes of red tide bloom and proliferation are still somewhat unknown, but the prevailing through is 

that the blooms begin offshore and can be supported closer to shore under certain conditions. Controls 

of bloom dynamics include physical parameters such as temperature and salinity, and nutrient form and 

availability. Evaluating the significance of a single factor is difficult (Vargo et al. 2008). Vargo (2009) 

reviewed the historic and current theories for K. brevis initiation and maintenance, and identifies 24 

hypotheses, falling into several main categories: 1) rainfall and/or riverine flux, 2) benthos or benthic 

flux, 3) water column hydrodynamics, and 4) chemical/allelopathy related. 

Vargo et al. (2004, 2008) evaluated many nutrient sources for their contributions to bloom initiation and 

maintenance: atmospheric deposition, estuarine flux, N-fixation by the cyanobacteria Trichodesmium, 

zooplankton excretion, benthic flux, and the decay of dead fish. Atmospheric deposition and benthic 

flux were found to be minor sources to N and P fluxes, while zooplankton and dead fish were possibly 

significant contributors. The combined estuarine flux from Tampa Bay, Charlotte Harbor, and the 

Caloosahatchee River was found to supply varying, but sometimes adequate levels of N and P to support 

K. brevis populations at moderate, but not high biomass levels. Hu et al. (2006) studied riverine nutrient 

inputs for major estuaries on the central west Florida Coast (Peace, Caloosahatchee, Alafia, and 

Suwannee Rivers) and determined that estuarine nutrient flux, even in a high discharge period following 

hurricanes (when nutrient concentrations also were elevated), could not support significant blooms. 

They suggested that submarine groundwater discharge accounts for the necessary missing nutrients and 

can initiate and sustain major bloom events off the coast of central west Florida. In the recent studies 

examining the role of various nutrient sources in supporting K. brevis blooms, a combination of sources 

is required to maintain a high biomass blooms (>106 cells/L). 

Coral or Hard Bottom Community Structure and Areal Extent

This information has yet to be quantified to date, although the habitat exists in the study area. Some 

information may be available based on observations taken during water quality sampling, and analysis 

will be performed to the degree allowable based on empirical data as part of the CCMP (Janicki 

Environmental 2009). 

Shellfish Production and Frequency/Duration of Bed Closures

St. Joseph Sound and Clearwater Harbor are not regulated shellfishing areas. Oyster bars present, and 

scallop occurrence has been monitored for the past several years. Scallops occur predominately in St. 

Joseph Sound (85%) (36 out of 42 occurrences from 2007-2009), but were also found in the Northern 

part of Clearwater Harbor (6 out of 42 occurrences; PCDEM unpublished data). Scallops were not 

surveyed in Boca Ciega Bay.
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Quantification of Landings from Commercial/Recreational Fisheries

The Florida Fish and Wildlife Conservation Commission (FWCC) measured angler pressure at 20 sites in 

St. Joseph Sound and Clearwater Harbor. Their angler survey distinguished between charter vessels, 

recreational vessels, and shore fishing. Results of angler surveys show that fishing is very much a part of 

the use of these estuaries (Figures 12-14).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 12. Average charter angler pressure per day for St. Joseph Sound and Clearwater Harbor. Data 

from angler survey by FWCC, and maps made by Janicki Environmental, Inc.
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 21 August 2010

Figure 13. Average private boat angler pressure per day for St. Joseph Sound and Clearwater Harbor. 

Data from angler survey by FWCC, and maps made by Janicki Environmental, Inc.
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 22 August 2010

Figure 14. Average shore angler pressure per day for St. Joseph Sound and Clearwater Harbor. Data 

from angler survey by FWCC, and maps made by Janicki Environmental, Inc.
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Existing Local Biological Indices

The Tampa Bay Benthic Index of macroinvertebrates has been applied in Boca Ciega Bay and perhaps 

elsewhere in the study area, but available data and studies were not mined before the publication of 

this report. No other biological indices have been developed for this area.

HABs, Fish Kills

Fish kills have been consistently reported for this region. Most are related to red tide and extreme cold 

events (see: http://research.myfwc.com/gallery/view_category.asp?catid=1357&subcatid=3227).

Hypoxia

Preliminary information suggests that hypoxia does not appear to be a significant issue in the study

area.

Other Biological Resources

Mangrove islands, oyster bars, and mudflats comprise important habitat for > 7,000 breeding pairs of 

birds in Clearwater Harbor (Audubon of Florida 2009), supported by the resident fishery.

Water Quality Studies

The Pinellas County Department of Environmental Management (PCDEM) monitors water quality 

throughout Pinellas County. The PCDEM report of water quality results from 2004 to 2008 (Levy et al.

2009) describes the monitoring program and summary results from that time period, and those results 

are reported in this section. The PCDEM sampling program during this period was a probabilistic design 

in which 32-36 sites in each unit (as shown in Figure 1) were sampled. Four samples were collected 

during each of the 8-9 sampling events. Water samples were collected and analyzed per DEP SOPs, with 

analysis done at a NELAC-certified lab. Data were loaded into Florida STORET. The County maintains 14 

stream flow gauges through the USGS and HDI, Inc. The sampling also included flow measurements at 

the remaining tributary sites that are not equipped with in-situ gauges. The data from this effort is used 

to develop system-wide loading estimates. The PCDEM has water quality data for Pinellas County 

waters from 1999-2003 from a fixed station monitoring program (see: 

http://www.pinellas.wateratlas.usf.edu/). 

Spatial interpolation analysis of PCDEM data from 2004-2008 shows the spatial distribution of dissolved 

oxygen (DO), chlorophyll a, and transmissivity in open waters of Pinellas County (Figures 15-17). 

Southern Clearwater Harbor, the Narrows, and North and Central Boca Ciega Bay (W3-W7) do not have 

as much direct contact with the Gulf of Mexico as the far northern and southern areas, resulting in 

higher salinities, lower DO, and higher chlorophyll a during either the wet or dry season (Levy et al. 

2009). Chlorophyll a concentrations are low (< 8 μg/L) in all areas during the dry/cool season (October -

May; Figure 16). During the wet/hot season (June-September), chlorophyll a concentrations are low (< 4 

μg/L) in St. Joseph Sound and moderate in Clearwater Harbor (4- 11 μg/L) and Boca Ciega Bay (6-15 

μg/L) (Figure 16). Mean chlorophyll a concentrations have declined over the period of record for St. 

Joseph Sound, Clearwater Harbor North, and Clearwater Harbor South, concomitant with changes in the 

ratio of total nitrogen to total phosphorus (Figures 18-20). Long term chlorophyll a data are still being 

evaluated for Boca Ciega Bay, and for TN and TP in all areas. 

The lower dissolved oxygen and higher chlorophyll a in the middle part of western Pinellas County (W3, 

W4, W5, W6) is likely due to larger watersheds feeding into those estuary areas and greater restriction 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 24 August 2010

of flow between those areas and the Gulf of Mexico (Levy et al. 2009). These areas correspond to the 

lowest SAV coverage and the highest density of development and dredge and fill operations.

Table 3. Median/mean values for sampling strata in western Pinellas County from 2004-2008. Strata 

as in Figure 1 (from Levy et al. 2009, Appendix A). 

Site Bottom DO 

(mg/L)

Chlorophyll 

a (μg/L)

TSS (mg/L) Turbidity 

(NTU)

Transmittance 

(%)

W1 6.65 / 6.70 2.3 / 1.4 14 / 12 1.6 / 1.2 88.36 / 91.53

W2 6.24 / 6.35 3.9 / 3.0 13 / 13 2.7 / 2.3 81.48 / 82.30

W3 5.96 / 5.98 5.0 / 4.1 15 / 14 3.6 / 2.6 75.67 / 78.78

W4 5.80 / 5.74 7.5 / 6.4 18 / 17 5.4 / 4.4 63.88 / 62.61

W5 4.88 / 4.54 13.1 / 7.5 13 / 12 4.3 / 3.6 64.91 / 69.25

W6 6.31 / 6.16 6.2 / 5.6 15 / 14 3.8 / 3.1 73.17 / 73.65

W7 6.04 / 6.27 6.5 / 6.0 16 / 15 3.6 / 2.6 73.19 / 74.58

W8 6.64 / 6.45 4.7 / 4.0 14 / 14 2.4 / 1.8 81.43 / 83.18

Table 4. Maximum/minimum values for sampling strata in Western Pinellas County from 2004-2008. 

Strata as in Figure 1 (from Levy et al. 2009, Appendix A). 

Site Bottom DO 

(mg/L)

Chlorophyll 

a (μg/L)

TSS (mg/L) Turbidity 

(NTU)

Transmittance 

(%)

W1 13.28 / 2.67 18.9 / 0.3 106 / 1 5.9 / 0.3 99.46 / 47.72

W2 13.03 / 1.54 13.3 / 0.3 41 / 2 15.0 / 0.7 97.02 / 55.98

W3 8.79 / 0.81 17.2 / 0.3 66 / 3 54.0 / 0.6 97.19 / 14.31

W4 11.97 / 0.19 31.8 / 0.5 43 / 1 23.0 / 1.0 91.52 / 20.70

W5 12.10 / 1.01 105.0 / 0.8 58 / 2 26.0 / 0.1 93.07 / 3.21

W6 12.76 / 0.29 31.9 / 0.3 40 / 3 19.0 / 0.2 94.77 / 33.00

W7 12.40 / 0.12 36.9 / 0.3 39 / 2 15.0 / 0.4 97.16 / 32.37

W8 13.87 / 1.58 35.5 / 0.3 34 / 1 18.0 / 0.4 97.47 / 43.48
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 15. Pinellas County bottom dissolved oxygen (mg/L) interpolation map applying kriging using 

2004-2008 data (Figure 10c in Levy et al. 2009). 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 26 August 2010

Figure 16. Pinellas County chlorophyll-a (μg/L) interpolation map applying inverse distance weighting 

using 2004-2008 data (Figure 9c in Levy et al. 2009). 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 27 August 2010

Figure 17. Pinellas County transmissivity % (at 660 nm) interpolation map applying kriging using

2004-2008 data (Figure 8c in Levy et al. 2009). 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 18. Mean chlorophyll a and TN/TP ratios for St. Joseph Sound from 2003-2008 (from Levy 

2010).

Figure 19. Mean chlorophyll a and TN/TP ratios for North Clearwater Harbor from 1992-2008 (from 

Levy 2010).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 20. Mean chlorophyll a and TN/TP ratios for South Clearwater Harbor from 1992-2008 (from 

Levy 2010).

Existing Regional Nutrient Loading Models 

Janicki Environmental, Inc. (2008) developed loading models for the Tampa Bay Estuary, and they are 

developing loading models for this region under the Comprehensive Conservation Management Plan 

(CCMP, Janicki 2009). 

Estuary Segments on 303(d) Impaired Waters List

Several estuarine waterbodies are on the 303(d) list for impairments of chlorophyll a, dissolved oxygen, 

or fecal coliform bacteria (Figure 21-23). Table 5 lists the WBIDs classified as “Estuary” that are impaired 

for some analyte on the 303(d) list. All of the listed impairments are for stream WBIDs that are within 

the urban areas; none of the open estuary areas have been deemed impaired. Three WBIDs are listed 

for fecal coliform exceedances, and five are listed for dissolved oxygen and nutrients (chlorophyll a; 

Table 5). 

TMDLs have been established for fecal coliforms in tidal portions of Klosterman Bayou, which empties to 

St. Joseph Sound (Albright 2008), and St. Joe Creek, which empties into Boca Ciega Bay (Kurisko 2008). 

Potential coliform sources include reclaimed water and municipal stormwater. The watershed is almost 

exclusively urban residential, so domestic animals likely contribute to high fecal coliform values. All 

residents in the watershed are on the sanitary sewer system.

The use of fecal coliforms as indicators of the presence of human pathogens has been under scrutiny in 

Florida for the past decade. One of the priorities of the Gulf of Mexico Alliance (GOMA) is the need to 

improve microbial source tracking and pathogen-detection methods for use under Gulf of Mexico 

conditions (GOMA 2009). The GOMA Pathogens Workgroup recently submitted comments regarding 

the status of EPA recreational water quality criteria (GOMA 2009). They expressed concern that the EPA 

recreational criteria were derived in places that do not represent Gulf of Mexico conditions, and that the 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 30 August 2010

use of fecal indicators was not appropriate for waters primarily influenced by animal sources. Areas in 

the Gulf of Mexico for which they thought the EPA criteria may not be appropriate included low 

population density coastal areas, areas of heavy rainfall, subtropical latitudes, and areas where waters 

contain a large amount of organic detritus material and/or colored dissolved organic matter (CDOM; 

GOMA 2009). Boehm et al. (2009) express similar concern about the current and proposed recreational 

criteria, and specifically call attention to the need for further research and revision in tropical waters 

and waters adversely impacted by urban runoff and animal feces. This is not to say that fecal coliform 

and Enterococci bacteria cannot indicate human sources or cannot co-occur with nutrient inputs; this 

suggests that there is ample evidence to caution against making the assumption that the presence of 

these bacteria automatically indicates the presence of anthropogenic nutrients.
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 21. Pinellas County waters impaired for chlorophyll a and Trophic State Index (lakes) based on 

FDEP 2009 verified lists and the 1998 303(d) list for Group 1 and Group 5 basins (Figure 3 in Levy et al.

2009).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 22. Pinellas County waters impaired for DO based on FDEP 2009 verified lists and the 1998 

303(d) list for Group 1 and Group 5 basins (Figure 2 in Levy et al. 2009).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Figure 23. Pinellas County waters impaired for bacteria based on FDEP 2009 Verified Lists and the 

1998 303(d) list for Group 1 and Group 5 basins (Figure 4 in Levy et al. 2009).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Table 5. Verified impaired waterbodies that empty into St. Joseph Sound, Clearwater Harbor, or Northern Boca Ciega Bay.

Waterbody 

ID (WBID)

Water 

Segment 

Name 

Parameters 

Assessed Using 

the 2001 

Impaired 

Surface Waters 

Rule (IWR)

Concentration 

Causing 

Impairment

Priority for TMDL 

Development

Comments 

(# Exceedances/# Samples) 

pp = Planning Period vp = Verified Period4

1508 KLOSTERMAN 

BAYOU

Coliform (Fecal 

Coliform)

> 400 

colonies/100 

ml

High pp = 6/57; vp = 7/37

1508 KLOSTERMAN 

BAYOU

Dissolved 

Oxygen

< 4.0 mg/L High pp = 71/350; vp = 49/231 Verified impaired. Nutrients were 

identified as the causative pollutant based on Chl-a 

data/nutrient impairment verification.

1508 KLOSTERMAN 

BAYOU

Nutrients (chla 

and Historic 

chla) 

Median TN = 

1.665 mg/L

High pp = Potentially impaired; vp = Verified impaired. Annual 

average Chl-a values exceeded 11 ug/l in 1999 - 2005, and 

values were 27.9, 32.44, 30.02, 22.67, 49.07, 38.14 and 45.29 

ug/l, respectively. For the historical listing, annual average Chla values in the verified period exceeded the minimum historical 

annual average value of 21.12 ug/l for 1990-1994 by more than 

50% in 2004 (38.14 ug/l), and 2005 (45.28 ug/l). Nitrogen is the 

limiting nutrient based on a median TN/TP ratio of 3.16 (133 

values). The verified period total nitrogen median = 1.665 (134 

values), total phosphorus median = 0.59 mg/l (150 values), and 

the BOD median = 3.25 mg/l (106 values). 

1538 CURLEW 

CREEK TIDAL

Dissolved 

Oxygen

< 4.0 mg/L High pp = 56/350; vp = 28/71 Verified impaired. Nutrients were 

identified as a causative pollutant based on Chl-a data/nutrient 

impairment verification.

1538 CURLEW 

CREEK TIDAL

Nutrients (chla) Median TN = 

1.65 mg/L

High pp = No data; vp = 33 / 62 Verified impaired. Annual average 

Chl-a values exceeded 11 ug/l in all years from 1999-2004, and 

the values were 27.29, 32.09, 35.35, 15.15, and 24.51 ug/l, 

respectively. Nitrogen is the limiting nutrient based on a 

median TN/TP ratio of 7.9 (67 values). The verified period total 

nitrogen median = 1.65 mg/l (68 values), total phosphorus 

median = 0.22 mg/l (67 values), and the BOD median = 2.6 

mg/l (47 values). 

1556 CEDAR CREEK 

(TIDAL)

Dissolved 

Oxygen

< 4.0 mg/L High pp = 64/221; vp = 42/82 Verified impaired. Nutrients were 

identified as a causative pollutant based on Chl-a data/nutrient 
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Waterbody 

ID (WBID)

Water 

Segment 

Name 

Parameters 

Assessed Using 

the 2001 

Impaired 

Surface Waters 

Rule (IWR)

Concentration 

Causing 

Impairment

Priority for TMDL 

Development

Comments 

(# Exceedances/# Samples) 

pp = Planning Period vp = Verified Period4

impairment verification.

1556 CEDAR CREEK 

(TIDAL)

Nutrients (chla) Median TN = 

1.05 mg/L

High pp = Potentially impaired; vp = Verified impaired. Annual 

average Chl-a values exceeded 11 ug/l in 1999 - 2005, and 

values were 13.91, 31.74, 12.85, 23.44, 3.363, 11.26 and 5.108 

ug/l, respectively. Nitrogen is the limiting nutrient based on a 

median TN/TP ratio of 6.89 (69 values). The verified period 

total nitrogen median = 1.05 mg/l (69 values), total phosphorus 

median = 0.15 mg/l (77 values), and the BOD median = 3 mg/l 

(47 values). 

1567 STEVENSON 

CREEK (TIDAL 

SEGMENT)

Dissolved 

Oxygen

< 4.0 mg/L High pp = 141/408; vp = 77/212 Verified impaired. Nutrients were 

identified as a causative pollutant based on Chl-a data/nutrient 

impairment verification.

1567 STEVENSON 

CREEK (TIDAL 

SEGMENT)

Nutrients (chla) Median TN = 

1.29 mg/L

High pp = Potentially impaired; vp = Verified impaired. Annual 

average Chl-a values exceeded 11 ug/l in 1999 - 2002 and 2004, 

and values were 16.08, 32.74, 59.37, 24.75 and 42.81 ug/l, 

respectively. Nitrogen is the limiting nutrient based on a 

median TN/TP ratio of 5.79 (116 values). The verified period 

total nitrogen median = 1.29 mg/l (117 values), total 

phosphorus median = 0.22 mg/l (121 values), and BOD median 

= 2 mg/l (92 values).

1633 MCKAY CREEK 

(TIDAL)

Coliform (Fecal 

Coliform)

> 400 

colonies/100 

ml

High pp = 34/36; vp = 1/11; Sufficient PP/VP data to assess. PP & 

most recent 20 samps (9/20) trigger VL; Assessment based on 

Period of Record data.

1633 MCKAY CREEK 

(TIDAL)

Dissolved 

Oxygen

< 4.0 mg/L High pp = 119/572; vp = 39/60 Verified impaired. Nutrients were 

identified as a causative pollutant based on Chl-a data/nutrient 

impairment verification. 

1633 MCKAY CREEK 

(TIDAL)

Nutrients (chla) Median TN = 

1.04 mg/L

High pp = No data; vp = 23 / 58 Verified impaired. Annual average 

Chl-a values exceeded 11 ug/l in 1999-2000, 2002, and 2004, 

and values were 12.22, 13.85, 11.48 and 21.52 ug/l, 

respectively. Nitrogen is the limiting nutrient based on a 

TN/TP ratio of 5.05 (56 values). Verified period total nitrogen 
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Waterbody 

ID (WBID)

Water 

Segment 

Name 

Parameters 

Assessed Using 

the 2001 

Impaired 

Surface Waters 

Rule (IWR)

Concentration 

Causing 

Impairment

Priority for TMDL 

Development

Comments 

(# Exceedances/# Samples) 

pp = Planning Period vp = Verified Period4

median = 1.04 mg/L (56 values), total phosphorus median = 0.2 

(61 values), and BOD = 2 mg/l (48).

1641 CROSS CANAL 

(SOUTH)

Coliform (Fecal 

Coliform)

> 400 

colonies/100 

ml

Low pp = 16/36; vp = 16/40.

1641 CROSS CANAL 

(SOUTH)

Dissolved 

Oxygen

< 4.0 mg/L Medium pp = 75/398; vp = 73/315 Verified Impaired. Nutrients were 

identified as a causative pollutant based on Chl-a data/nutrient 

impairment verification.

1641 CROSS CANAL 

(SOUTH)

Nutrients (chla) Median TN = 

1.11 mg/L

Medium pp = Potentially impaired; vp = Verified impaired. Annual 

average Chl-a values exceeded 11 ug/l in 1999 and 2001 - 2005, 

and values were 17.75, 14.84, 12.34, 18.95, 14.17 and 17.38 

ug/l, respectively. Nitrogen is the limiting nutrient based on a 

median TN/TP ratio of 6.98 (150 values). Verified period total 

nitrogen median = 1.11 mg/l (152 values), total phosphorus 

median = 0.16 mg/l (159 values), and BOD = 2 mg/l (123 

values).

1662 PINELLAS 

PARK DITCH 

NO 1 (TIDAL 

SEGMENT)

Coliform (Fecal 

Coliform)

> 400 

colonies/100 

ml

High pp = 8/12; vp = 2/10; Sufficient PP/VP data to assess. PP & 

"PP+VP" samp exceedance rates trigger VL (PP+VP = 10/22), & 

POR data shows multiple post-VP exceedances in 2006. Area is 

highly developed. Assessment based on Period of Record data.

1662 PINELLAS 

PARK DITCH 

NO 1 (TIDAL 

SEGMENT)

Dissolved 

Oxygen

< 4.0 mg/L High pp = 6 / 23; vp = 3 / 11; PP+VP provide sufficient data to assess. 

Combined PP+VP dataset yields 9/22, and results for most 

recent 20 samps = 8/20. Both exceed threshold for verification. 

Area is highly developed. Assessment based on Period of 

Record data.

1701 BEAR CREEK Coliform (Fecal 

Coliform)

> 400 

colonies/100 

ml

Low pp = 31/37; vp = No data; Sufficient PP data (all 1994-96) to 

assess. Area has been largely built out for many years. 

Assessment based on Period of Record data.

1701 BEAR CREEK Dissolved 

Oxygen

< 5.0 mg/L Medium pp = 102/346; vp = 58/171 Verified impaired. There are a 

sufficient number of DO violations to place DO on the verified 

list. However, unable to link low DO to a causative pollutant 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Waterbody 

ID (WBID)

Water 

Segment 

Name 

Parameters 

Assessed Using 

the 2001 

Impaired 

Surface Waters 

Rule (IWR)

Concentration 

Causing 

Impairment

Priority for TMDL 

Development

Comments 

(# Exceedances/# Samples) 

pp = Planning Period vp = Verified Period4

(BOD or nutrients).

1716 CLAM BAYOU 

DRAIN (TIDAL)

Dissolved 

Oxygen

< 4.0 mg/L High pp = 2/4; vp = 5/8 Verified impaired. Nutrients were identified 

as a causative pollutant. Verified period total nitrogen median 

= 1.26 mg/L (5 values), total phosphorus = 0.14 (5 values), and 

BOD median = 5 mg/l (7 values). 

1618C LONG 

BAYOU/CROSS 

BAYOU

Dissolved

Oxygen

< 4.0 mg/L Medium pp = 17/67; vp = 43/210 Verified impaired. Nutrients were 

identified as a causative pollutant based on Chl-a data/nutrient 

impairment verification.

1618C LONG 

BAYOU/CROSS 

BAYOU

Nutrients (chla) Median TN = 

0.96 mg/L

Medium pp = Potentially impaired; vp = Verified impaired. Annual 

average Chl-a values exceeded 11 ug/l in 2003 - 2005, and 

values were 19.92, 11.25, and 16.73 ug/l, respectively. 

Nitrogen is the limiting nutrient based on a median TN/TP ratio 

of 6.26 (118 values). The verified period total nitrogen median 

= 0.96 mg/l (119 values), total phosphorus median = 0.17 mg/l 

(114 values), BOD = no data.

1668E ST JOE CREEK 

(TIDAL 

SEGMENT)

Dissolved 

Oxygen

< 4.0 mg/L Medium pp = 45/197; vp = 33/122 Verified Impaired. Nutrients and 

BOD were identified as a causative pollutant based on Chl-a 

data/nutrient impairment verification. 

1668E ST JOE CREEK 

(TIDAL 

SEGMENT)

Nutrients (chla 

and Historic 

chla)

Median TN = 

1.14 mg/L

Medium pp = Potentially impaired; vp = Verified impaired. Annual 

average Chl-a values exceeded 11 ug/l in 1999 - 2002 and 2004, 

and values were 40.48, 26.65, 21.1, 23.06, and 23.87 ug/l, 

respectively. For the historical listing, annual average Chl-a) 

values in the verified period exceeded the minimum historical 

annual average value of 16.31 ug/l for 1990 -1994 by more 

than 50% in two consecutive years in 1999 (40.48 ug/L) and 

2000 (26.65 ug/l). Nitrogen is the limiting nutrient based on a 

median TN/TP ratio of 6 (62 values). The verified period total 

nitrogen median = 1.14 mg/l (63 values), total phosphorus 

median = 0.18 mg/l (66 values), and BOD median = 3.05 mg/l 

(52 BOD values).
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

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Numeric Nutrient Criteria Recommendations 

Water quality targets for SAV protection are being established for St. Joseph Sound and Clearwater 

Harbor by Janicki Environmental. Their work is incorporating water quality data, loading estimates, 

protection of SAV, fish, birds, and other uses. FDEP does not plan to propose numeric nutrient criteria 

for these regions until their work is complete. 

Nutrient loading targets have been set for southern Boca Ciega Bay as part of the Tampa Bay Nitrogen 

Management Consortium (TBNMC), and FDEP supports those recommendations. Northern Boca Ciega 

Bay is similar to Southern Clearwater Harbor in physical and chemical characteristics, and it may be 

appropriate to adopt the same criteria for both areas. The TBNMC has proposed a chlorophyll a target 

of 5.1 μg/L for Lower Tampa Bay, which is adjacent to Southern Boca Ciega Bay. FDEP will evaluate 

whether that target would be an appropriate criterion for Southern Boca Ciega Bay. FDEP welcomes 

comments from stakeholders on these ideas, and will continue to work with the Pinellas County 

Department of Environmental Management and the Tampa Bay Estuary Program to develop numeric 

nutrient criteria for this region. 
Nutrient Criteria Technical Support Document St. Joseph Sound and Clearwater Harbor

Draft 39 August 2010

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