# PROPOSED

NUMERIC NUTRIENT CRITERIA

FOR CLEARWATER HARBOR

AND SAINT JOSEPH SOUND

Prepared for:

Pinellas County Watershed Management Section

Department of Environment and Infrastructure

300 South Garden Avenue

Clearwater, Florida 33756

Prepared by:

Janicki Environmental, Inc.

1155 Eden Isle Drive NE

Saint Petersburg, Florida 33704

September, 20112 

## 1.0 Introduction

The Florida Department of Environmental Protec tion (FDEP) is currently developing a rule to

establish numeric nutrient criteria for a number of water body types. The following summarizes

FDEP’s view on the development of numeric nut rient criteria in Florida (FDEP website, 2011).

The overarching FDEP goal is to “manage nutrien ts in surface (and groundwater) at loadings or

concentrations that result in protection and maintenance of healthy, well-balanced aquatic

communities”. Absent site-specific analyses, cr iteria should be based on a quantifiable linkage

between anthropogenic nutrient enrichment and a biological response (such as seagrass growth)

that can be used to numerically interpret the narrative nutrient criteri a. There is value in knowing

whether nutrient concentrations are potentially eleva ted to environmentally harmful levels, but it is

important to identify adverse biological effects an d determine if they are linked to nutrients before

deciding that nutrient reductions should be pursued.

The Department recognizes the role of site-spe cific factors that affect numeric responses and

proposes to base new standards on establishing a systematic numeric interpretation of the existing

narrative criteria. This concept is intended to implement Rule 62-302.530 (47)(b), FAC, which

states, “in no case shall nutrient concentrations of a body of water be altered so as to cause an

imbalance in natural populations of aquatic flora or fauna.”

As envisioned by FDEP, the narrative nutrient crite ria would continue to apply to all waterbodies,

and numeric interpretations would be applied when adequate scientific information is available.

The narrative criteria would be implemented using a sy stematic structure that numerically interprets

the narrative nutrient criteria for each waterbody in a hierarchical manner.

This document provides background information conc erning the estuarine systems of Clearwater

Harbor and Saint Joseph Sound, including a brie f physical characterization of the system and a

summary of work completed to assess the state of the estuarine natural resources and develop

management targets and thresholds that can be used to evaluate changes in the estuary over time

compared to an identified reference period that re presents full support of aquatic life uses in

accordance with FDEP and EPA standards. The info rmation provided in this document is the result

of an agreement by a consortium of municipa l governments, Pinellas County and the Southwest

Florida Water Management District to develop a Comprehensive Conservation and Management

Plan (CCMP) for Clearwater Harbor and Saint Jo seph Sound (CHSJS). This effort is ongoing with

completion scheduled for December, 2011. As pa rt of this CCMP, management goals have been

developed to serve as guidance for evaluating the condition of the estuarine systems of the CHSJS.

These goals as they relate to the establishment of numeric nutrient criteria for these waterbodies are

explained in further detail below.



### The CHSJS Study Area

The CHSJS study area encompasses much of we stern Pinellas County, includes both estuarine

segments and their associated watersheds, a nd borders the management boundary of the Tampa

Bay Estuary Program. The segments are Saint Jo seph Sound (SJS); Clearwater Harbor North (CHN),

and Clearwater Harbor South (CHS) (Figure 1-1). The jurisdictions within the CCMP are provided

in Figure 1-2.3 Figure 1-1. The CHSJS CCMP area in relati on to the Tampa Bay Estuary Program boundaries.4 Figure 1-2. Jurisdictions within the CHSJS and its watershed.5 The Saint Joseph Sound estuary occupies approximately 18,000 acres within Pinellas County and is

bounded to the north by the Anclote Anchorage at the mouth of the Anclote River and to the south

by Dunedin Causeway. Several barrier islands including Anclote Key, Three Rooker Bar, and

Honeymoon Island mark the western boundary of SJ S. Large passes between these barrier islands

provide significant tidal interaction with the Gulf of Mexico. Much of the eastern shoreline of the

estuary has been hardened by seawall and rip-rap, su ch as can be seen along Klosterman Bayou. In

contrast, the western shorelines along the barrier is lands have remained largely in a natural state.

The natural areas on the barrier islands provid e major public recreation features including

Honeymoon Island State Recreation Area and Ancl ote Key Preserve State Park, with the latter

accessible only by boat.

Clearwater Harbor North occupies approximatel y 5,876 acres and is substantially narrower and

somewhat less connected to the Gulf of Mexico than Saint Joseph Sound. Hurricane Pass, in the

northern region of Clearwater Harbor North provides the only direct tidal interaction with the Gulf

of Mexico within the segment; however much of the water in CHN also exchanges with the Gulf

via Clearwater Pass to the south. Clearwater Ha rbor North is bounded to the west by Caladesi

Island and Clearwater Beach Island and to the east by mainland Florida and the cities of Dunedin

and Clearwater. The great majority of the estuary’ s shoreline is hardened by seawall and rip-rap to

accommodate coastal development and to prevent erosion of the shor eline, including much of the

barrier islands. Large areas of the bay bottom have been dredged and filled to create residential

canal developments that extend into the estuary. Major public recreation features in Clearwater

Harbor North include Caladesi Isla nd State Park and Clearwater Beach.

Clearwater Harbor South is the smallest estuarin e segment (3,831 acres) and least tidally connected

of the three bay segments with tidal exchange occu rring principally through Clearwater Pass in the

northern portion. The construction of the Cl earwater Memorial Causeway, much of which

involved filling the bay bottom to allow road construction, has restricted the connection between

Clearwater Harbor North and Clearwater Harbor South with north/south tidal exchange limited on

the eastern and western sides of the causeway. From Clearwater Pass at the north end of this

segment, the segment quickly narrows from approximat ely 2 km across to less than 0.2 km in width

at The Narrows where it adjoins to Boca Ciega Ba y via a dredged channel that serves as the

Intracoastal Waterway. Much of the southern exte nt of Clearwater Harbor South from Belleair to

Indian Rocks Beach has been filled to create reside ntial canal developments that form its western

boundary along Sand Key.

Pinellas County, in cooperation with local scientists and FDEP, has developed a list of symptoms of

nutrient enrichment in the CHSJS, along with poten tial explanations of these expressions, to aid in

development of numeric nutrient crite ria for this area. This listing is provided in Tables 1-1 and 1-2

below and the entire summary is provided as Appendix A. The tables below provide a summary of

potential responses to nutrients, and whether these re sponses are currently or historically observed.6 Table 1-1. Checklist of nutrient enrichment symptoms.

‐ = Empty cell/no data

Response Variable Observed

Historically? Observed

Currently? Explanation Source

Low dissolved

oxygen (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 summer. 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 chl a

concentrations Yes No Historical loss of SAV likely related to chl a ;

however, concentrations have decreased

or remained constant since 1992. Levy 2010

Phytoplankton

blooms (nuisance

or toxic) Yes No 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 Boca Ciega Bay

from 1950 to 1982, and some loss likely

occurred in Clearwater Harbor. SAV

coverage in Boca Ciega Bay rebounded to

80% former coverage in 2008. SAV

coverage increased 16% between 1999 and

2008. Losses occurred in all areas due to

dredging and filling, and that loss is

considered permanent and not related to

nutrients or water clarity. K. Levy, PCDEM,

personal

communication;

SWFWMD SAV

data

Emergent/

shoreline

vegetation changes Yes

‐ Much of the mainland shoreline has been

developed, so there are many seawalls and

little intact shoreline vegetation. ‐

Coral/hard

‐ bottom

community

changes or loss Unknown

‐ There is some hard

‐ bottom community in

this area, but it has not been studied. ‐

Impacts to benthic

community Unknown

‐  ‐ ‐

Fish kills Yes, limited

in space and

time ‐ Fish kills have periodically 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. ‐7 Table 1-2. Checklist of additional factors.

‐ = Empty cell/no data

Nutrient Factors Observed? Explanation Source

Increased nutrient loading or

concentrations No Historical increases, but nutrient loading from

humans has decreased in the past 10 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

‐ ‐

The CHSJS watershed receives approximately 50 inch es of rainfall annually with nearly half of the

total occurring over four months between June a nd September (Figure 1-3). The largest source of

freshwater inflow into the CHSJS estuary is the An clote River. The remaining freshwater sources

are smaller creeks and small magnitude coastal sp rings including Klosterman Creek, Curlew Creek,

Cedar Creek, Spring Branch, Stevenson Creek, Sm ith Creek, McKay Creek and Wall Spring. While

these tributaries deliver a much lower volume of freshwater than the Anclote River, they remain

ecologically import and contribute significant amounts of freshwater, nutrients and sediments to the

estuary. Direct runoff from coastal lands, direct precipitation to the estuary as well as direct

discharge from stormwater outfalls also contribute fr eshwater and nutrients to the estuarine waters.

Figure 1-3. Distribution of monthly rainfall at City of Tarpon Springs rain gage over a 75 year period of

record.8 

## 2.0 Objective

The objective of this document is to propose estuar ine numeric nutrient criteria specific to the three

open estuarine segments of the CHSJS: Saint Joseph Sound, Clearwater Harbor North, and

Clearwater Harbor South. These concentration- based criteria were developed using a “Reference

Period” approach.



## 3.0 Development of S eagrass and Chlorophyll a Targets

This section describes the data and analytical appr oaches to establishing seagrass and chlorophyll a targets for the CHSJS.



### 3.1 Background and Rationale

The CCMP for Clearwater Harbor and Saint Joseph Sound is modeled on similar work conducted

by the EPA’s three National Estuary Programs of southwest Florida. The identification of water

quality response endpoints is a critical step in identifying management level criteria for these

waterbodies and substantial efforts have been made to identify response indicators that can be used

to evaluate the health of the estuaries. An outcome of this work has been the realization that each

estuary has unique attributes that govern sp ecific cause and effect relationships between

anthropogenic stressors and water quality respons es. Further, in some cases scientifically

defensible cause and effect relationships betwee n nutrients and water quality responses have not

been apparent. Factors including estuarine reside nce times and nutrient loadings play an important

role in the assimilation of nutrients within the estuary and their expression. In this way, each

estuary is different and therefore site-specific criteria are beneficial to ensure the appropriate

management actions are taken. In the CHSJS, seagra sses are a critical indicator of estuarine health

and provide a critical endpoint in the development of numeric nutrient criteria.



### 3.2 Development of Seagrass Targets

Seagrasses are keystone communities in the CHSJS, as well as the majority of the estuaries in

southwest Florida. Seagrass health and success de pends on good water quality and water clarity,

making seagrasses useful indicators of ecosystem hea lth. As part of the CHSJS State of the Resource

Report (Janicki Environmental, 2011), historical phot ography was used to estimate seagrass acreage

in the estuary. National Archive’s ca. 1942 were used and supplemented by photographs taken in

1957 in the western portion of Saint Joseph Sound. These estimates were then compared to recent

surveys conducted by the SWFWMD after adjusting for non-restorable areas, such as dredging of

the Intracoastal Waterway and other dredge and fill projects.

Current seagrass areal extents are 81%, 73% and 67% of historic estimates for Saint Joseph Sound,

Clearwater Harbor North and Clearwater Harbor S outh, respectively (Figure 3-1). While Clearwater

Harbor South has lost the largest proportion of seagra sses relative to its historic estimate, St Joseph

Sound lost more acreage than the other segments.9 Figure 3-1. Comparison of historic seagrass esti mates circa 1940’s (adjusted for non-restorable areas) and

most recent estimates from the SWFWMD (2010).

Despite these historical losses, seagrass acreage has been trending upward since 1999 throughout

Clearwater Harbor and there have been substantial recent gains in Saint Joseph Sound. The most

recent seagrass mapping efforts, completed in 2010, indicate that in Saint Joseph Sound, seagrass

cover in 2010 was 15% higher than in 1999, an in crease of 1,680 acres (Figure 3-2). In Clearwater

Harbor North, seagrass acreage increased 56%, from 2,416 acres in 1999 to 3,758 acres in 2010.

Seagrass cover in Clearwater Harbor South incr eased 66%, from 545 acres to 902 acres between

1999 and 2010 indicating that limiting factors for seagrass have improved over recent history

Historical seagrass estimates were used to deve lop seagrass areal extent targets in CHN and CHS.

Given the recent trajectory in seagrass acreage in these segments, the historical acres (adjusted for

non-restorable areas) were thought to be reasona ble estimates of the potential gains. However, in

Saint Joseph Sound large areas of historic seagrass loss appear to be due to physical disturbances

such as barrier island migration, the dredging of the ICW and its associated impacts on current

velocities, and depth and wave energy, as well as the potential effects of episodic biological

perturbations and grazing events as described in the State of the Resource Report (Janicki

Environmental, 2011). Given these considerations , it was deemed unrealistic to develop a target

for Saint Joseph sound that is based on historical conditions. Consequently, the seagrass areal target

acreage for Saint Joseph Sound is an average of the two most recent surveys. Therefore, the

segment-specific seagrass targets proposed for the CHSJS are:

 St, Joseph Sound 12,539 acres

 Clearwater Harbor North 5,142 acres

 Clearwater Harbor South 1,595 acres10 Figure 3-2. Change in seagrass areal extent betw een 1999 and 2010 for each CHSJS estuarine segment.



### 3.3 Development of Chlorophyll a Targets and Thresholds

Pinellas County’s ambient water quality monito ring program uses both a fixed station and

probabilistic sampling routine. The estuarine, open bay water quality sampling program was

historically based on fixed stations until 2003 when a probabilistic sampling design was initiated

(Janicki Environmental, 2003). The probabilistic rou tine was designed to generalize water quality

information collected at particular locations to the entire study area with statistical confidence

specifically to fulfill the Pinellas County needs while also being applicable to the FDEP for use in

their Impaired Waters assessments. The historic fixed stations locations and a the distribution of

samples collected under the probabilistic design between 2003 and 2009 in Saint Joseph Sound,

Clearwater Harbor North, and Clearwater Harbor South is provided in Figures 3-3 through 3-5,

respectively. The historic fixed stations in the estuary are highlighted with a purple triangle.11 Figure 3-3. Location of water quality sampling stations in Saint Joseph Sound. Historical fixed stations

(purple triangles); probabilistic samples collected between 2003 and 2009 (green circles).12 Figure 3-4. Location of water quality sampling stati ons in Clearwater Harbor North. Historical fixed

stations (purple triangles); probabilistic samples collected between 2003 and 2009 (green circles).13 Figure3-5. Location of water quality sampling stations in Clearwater Harbor South. Historical fixed

stations (purple triangles); probabilistic samples co llected between 2003 and 2009 (green circles).14 In the past, a single fixed station within each estuarine segment was sampled monthly as a primary

site. The other fixed stations were sampled bi-m onthly as secondary sites. The location of these

sites was based on professional judgment and sometimes located to monitor known or suspected

pollutant sources. When the probabilistic de sign was implemented in 2003, the sampling

frequency was divided into nine equivalently distributed “sampling periods” and the exact

sampling date within each samp ling period was also assigned randomly from a list frame of

potential sampling dates (Janicki Environmental, 200 3). From 2003-2007, nine sampling periods

were used within a year and a total of 36 samples we re collected from each of three sampling strata

in a year. In 2008, due to budget constraints, the County reduced the number of sampling periods

from 9 to 8. Each annual sampling allocation was divided into eight periods and a total of 32

samples were collected in each stratum.

The average chlorophyll a concentration from data collected between 2003 and 2009 was 2.7 μg/L,

4.0 μg/L, and 5.7 μg/L for Saint Joseph Sound, Cl earwater Harbor North, and Clearwater Harbor

South, respectively. A brief comparison of recent data collected using the probabilistic design

(2003-2009) and historical fixed station data colle cted from 1992-2002 is provided below to give

descriptive context to changes in water quality over time. For the purposes of understanding past

and present conditions of these segments it was im portant to understand if and how these disparate

datasets may be used in the target-setting process.

A descriptive assessment comparing recent and hi storical water quality suggests that water quality

conditions with respect to chlorophyll a concentrations have improved over time. Average

chlorophyll a concentrations based on the historical fixed station data were 6.2 μg/L, 7.2 μg/L, and

8.3 μg/L for Saint Joseph Sound, Clearwater Ha rbor North, and Clearwater Harbor South,

respectively. The distribution of chlorophyll a concentrations in historical and recent datasets is

provided in Figure 3-6. Note th at the distribution of chlorophyll a concentrations is higher in the

historical fixed station data than in the recent data and that the same latitudinal (north-south)

gradient exists in both datasets suggesting a pe rsistent latitudinal gradient in chlorophyll a concentrations throughout the study area. A ll within-segment differences were statistically

significant using the Wilcoxon Rank Sum test (Sokal and Rohlf, 1984).

Further supporting evidence of improving chlorophyll a concentrations comes from an examination

of timeseries trends in chlorophyll a. Annual averages for chlorophyll a , TN and TP were calculated

for each historical station within a segment. The probabilistic data were assigned a station name

corresponding to the strata name for the segm ent (i.e., W1 for Saint Joseph Sound, W2 for

Clearwater Harbor North, and W3 for Clearwater Harbor South) (Figure 3-7). Annual averages

were calculated for all of the “random” samples w ithin the segment for each year. The annual

averages for each timeseries were then plotted with each trend depicted as a single line (Figures 3-8

– 3-10). There are several elements of note in these figures.

 First, there is substantial correlation in the timeseries trend among fixed stations over time in

each segment.

 Second, the fixed station trend appears to conti nue with the timeseries of probabilistic data.

 Lastly, all annual average chlorophyll a values were well below the FDEP state threshold of

11 μg/L other than two stations in Clearwat er Harbor South in 1997 and 1998 (even in

these years the overall segment average was below the threshold value).15 Figure 3-6. Distribution of chlorophyll a concentrations in historical fixed station “Fixed” and recent

probabilistic “Random” data in all three CHSJS segments.

Figure 3-7. The geographic extent of the CHSJS segmen ts for which numeric nutrien t criteria are proposed.16 Figure 3-8. Annual average chlorophyll a concentrations in Saint Joseph Sound. Individual fixed stations

sampled between 1992 and 2002 and the probabilistic data sampled since 2003 (designated as “Station

W1”). The broken vertical line indicates the b eginning of the probabilistic data collection.

Figure 3-9. Annual average chlorophyll a concentrations in Clearwater Harbor North. Individual fixed

stations sampled between 1992 and 2002 and the pr obabilistic data sampled since 2003 (designated as

“Station W2”). The broken vertical line indicates th e beginning of the probabilistic data collection.17 Figure 3-10. Annual average chlorophyll a concentrations in Clearwater Harbor South. Individual fixed

stations sampled between 1992 and 2002 and the pr obabilistic data sampled since 2003 (designated as

“Station W3”). The broken vertical line indicates th e beginning of the probabilistic data collection.

This information suggests that, while there is a difference in the average water quality among

stations within a segment, water quality at these stations appears to respond similarly to common

drivers of water quality within the segment on an annual time scale. Further, individual station

averages tended to co-vary over time during the hi storic fixed station sampling period despite the

different sampling frequencies between stations w ithin a segment. This information is supporting

evidence that the fixed station in formation may be generally representative of trends in water

quality over time on an annual time scale and that variability within a segment is a significant

attribute lending credence to the implementation of the probabilistic design which is more likely to

represent the true average condition of the segment.

The evidence provided by these descriptive plots suggests that all segments are currently meeting

their designated use with respect to maintaining healthy chlorophyll a concentrations and thereby

seagrass extent. Chlorophyll a concentrations have been declining in both Saint Joseph Sound and

Clearwater Harbor North over time at the fixed st ation sites suggesting conditions have improved in

these segments since the early 1990s while remainin g stable in Clearwater Harbor South.

For the purposes of the CHSJS CCMP, the estuary wa ter quality goal was estab lished to ensure that

water quality conditions in the estuary are protec tive of seagrasses. Given that seagrasses are

currently improving throughout the CHSJS estuar y, it was concluded that recent water quality

conditions are sufficient to maintain full aquatic life uses in the estuary. Therefore, a reference

period approach was used to establish management targets and thresholds used to monitor water

quality in the estuarine open bay waters of the CCMP. The reference period was defined as the

2003-2009 time period. The Reference Period approach was used to establish the chlorophyll a

targets and thresholds for the CHSJS segments. The Reference Period was defined as the population

of data collected between 2003 and 2009 in Pinellas County’s monitoring strata “W1”,

“W2”,”W3”, representing Saint Joseph Sound, Clea rwater Harbor North, and Clearwater Harbor18 South, respectively (Figure 3-7). The chlorophyll a targets for each segment (i.e., the annual

geometric means for the reference period) as reported in Janicki Environmental (2011) are:

 St, Joseph Sound 1.9 μ g/L,

 Clearwater Harbor North 3.5 μ g/L, and

 Clearwater Harbor South 4.8 μ g/L.

A distinction is made between a target , i.e., a desired chlorophyll a concentration and a threshold

, i.e., a chlorophyll a concentration above which undesirable chlorophyll a concentrations exist.

The threshold value for these constituents was defin ed as a value that would indicate that water

quality was significantly higher than that observed over the reference period. The threshold value

was calculated based on statistical theory that if chlorophyll a concentrations in any year were not

different from reference period conditions, its geo metric average value would be lower than the

reference period mean +1.96 times the standard de viation of the annual geometric averages with

known confidence. The proposed chlorophyll a thresholds, expressed as annual geometric means,

for each segment

 St, Joseph Sound 3.1 μ g/L,

 Clearwater Harbor North 5.4 μ g/L, and

 Clearwater Harbor South 7.6 μ g/L.



## 4.0 Proposed Numeric Nutrient Criteria

Quantitative statistical analyses suggested that neith er nutrient concentrations nor nutrient loadings

alone were confident pred ictors of the chlorophyll a concentrations used as an indicator of

estuarine health (Janicki Environmental, 2011). While within-segment analysis did not reveal a

direct link between nutrients and phytoplankton concentrations, descriptive plots suggested a

north/south gradient in chlorophyll a concentrations that appeared to be principally a function of

residence times. The direct influence of tidal exc hange with the Gulf of Mexico is most pronounced

in Saint Joseph Sound and least pronounced in Clea rwater Harbor South. The increased residence

time of water in the Clearwater Harbor South segm ent seemingly allows for a higher concentration

of phytoplankton as shown in Figure 4-1. In this plot the chlorophyll a and TN concentrations are

standardized so that they are on the same scale (i.e., units of standard deviation from their longterm average). Therefore, blue dots represent lo wer than average concentrations and red dots

indicate higher than average concentrations. This suggests that other factors are likely influencing

the theoretical stressor-response rela tionship between TN and chlorophyll a responses.

A comparison of TN concentrations (Figure 4-2) su ggests that TN concentrations were more similar

between historical and recent data than observed in the chlorophyll a concentrations (Figure 3-6),

especially in Clearwater Harbor North and Clearw ater Harbor South. A Wilcoxon Rank Sum test

suggests that statistically different distributions between the fixed and probabilistic data were only

found in Saint Joseph Sound. This difference was likely due to the biased location of the fixed

stations towards the southern end of the segment.

Therefore, for the purposes of the CHSJS CCMP, th e estuary water quality goal was established to

ensure that water quality conditions in the estuary ar e protective of seagrasses. Given the results of19 analysis described above, and the fact that seagra sses are currently improving throughout the CHSJS

estuary, it was concluded that recent TN concentr ations are sufficient to maintain full aquatic life

uses in the estuary. Therefore, a reference pe riod approach was used to establish management

targets and thresholds used to monitor water quality in the estuarine open bay waters of the CCMP.

The reference period was defined as the 2003-2009 time period.

Figure 4-1. Spatial distribution of chlorophyll a (left) and TN (right ). Red dots indicate significant clustering

of higher than average values and blue dots i ndicate statistically lower than average values.

Figure 4-2. Distribution of TN concentrations (m g/L) in historical fixed station “Fixed” and recent

probabilistic “Random” data in all three CHSJS segments.20 Both DEP and EPA have expressed a preference for criteria proposed as annual geometric averages.

The geometric average is calculated by first usin g the natural log transformation of the raw data,

calculating an average and then exponentiating that average to derive the geometric average.

Target TN concentrations (mg/L) for each CHSJ S estuarine segment were defined by the overall

average of the annual geometric averages during the reference period.

As discussed above, a distinction is made between a target , i.e., a desired TN concentration and a

threshold , i.e., a TN concentration above which undesirable TN concentrations exist A threshold

value for these constituents was defined as a va lue that would indicate that water quality was

significantly higher than that observed over th e reference period. The threshold value was

calculated based on statistical theory that if TN c oncentrations in any year were not different from

reference period conditions, its geometric average value would be lower th an the reference period

mean +1.96 times the standard deviation of the annual geometric averages with known

confidence. The proposed segment-specific TN thresholds for each segment are:

 St, Joseph Sound 0.66 mg/L,

 Clearwater Harbor North 0.61 mg/L, and

 Clearwater Harbor South 0.58 mg/L.

The annual geometric means for chlorophyll a and TN should be derived strictly from water quality

sampling according to Pinellas County’s probabilistic water quality sampling design for estuaries in

their designated strata “W1”, “W2” , and “W3” co rresponding to Saint Joseph Sound, Clearwater

Harbor North and Clearwater Harbor South, respecti vely. These thresholds are not to be considered

as end of pipe criteria for regulatory purposes.

The proposed TN criteria will be used to evaluate water quality with respect to not allowing for

degradation of water quality from that observed over recent time period (i.e., 2003-2009) when the

open bay estuarine segments were fully meeting th eir designated uses. Within this context, an

excursion is defined as when an annual geometric average for a particular constituent has exceeded

the threshold value. However, a single excursion of the threshold value does not necessarily mean

that there has been significant degradation of wa ter quality as described in the next section on

implementation.



## 5.0 Implementation

As described in the State of the Resource Repo rt (Janicki Environmental, 2011), there have been

times when estuarine water qua lity values for chlorophyll a and TN have historically exceeded the

proposed threshold values while the estuarine wate rs were meeting full aquatic life uses. While it

is known that there is a limit for nutrient inputs above which any estuary would become

compromised in meeting its full aquatic support, without a defensible quantitative stressor-response

relationship, this limit cannot be predicted. The reference period approach was used to provide

potential numeric criteria for TN in keeping with EPA’s policies on anti-degradation given that these

areas are of special significance with regard to their designation as aquatic preserves.

The proposed compliance assessmen t strategy involves two steps. The initial step is the

comparison of the annual geometric average chlorophyll a concentrations of each segment to the

established chlorophyll a thresholds. Compliance is achieved if the geometric average is less than

or equal to the chlorophyll a threshold value. The threshold TN concentrations can be used to test21 a sample geometric mean for any given year fo r compliance with the established targets and

thresholds. Any sample geometric mean higher th an these values would then be considered an

excursion. If the chlorophyll a threshold and TN threshold have been exceeded in more than two

years during any five-year period, an assessment of the seagrass areal extent in that segment should

be conducted. The justification for this “2-in-5 year” compliance assessment is summarized in

Appendix B.

Lastly, it is critical that the data collected to assess compliance with both chlorophyll a thresholds

and TN criteria must be defensibly comparable, i.e., collected in a similar temporal and spatial

manner to the data used to establish the threshol ds and criteria. The annual geometric means for

chlorophyll a and TN should be derived strictly from water quality sampling according to Pinellas

County’s probabilistic water quality sampling design fo r estuaries in their designated strata “W1”,

“W2” , and “W3” corresponding to Saint Joseph Sound, Clearwater Harbor North and Clearwater

Harbor South, respectively. Again, these thresholds are not to be considered as end of pipe criteria

for regulatory purposes.22 

## 6.0 References

Florida Department of Environmenta l Protection (FDEP) website. 2011.

http://www.dep.state.fl.us/water/wqssp/nutrients/index.htm

Janicki Environmental, Inc. 2003. A design of a surface water quality monitoring program for

Pinellas County. Prepared for Pinellas County En vironmental Resource Management division.

Clearwater, FL.

Janicki Environmental, Inc. 2011. State of the Res ource Report for Clearwater Harbor and Saint

Joseph Sound. Prepared for Pinellas County Depa rtment of Environment and Infrastructure.

Clearwater, Florida..

Sokal, R. R. and F. J. Rohlf. 1981. Biomet ry. W.H Freeman and Company. New York.

# Appendix A.

Site-Specific Information

in Support of Establishing

Numeric Nutrient Criteria in

St. Joseph Sound,

Clearwater Harbor, and

Boca Ciega Bay

# Site-Specific Information

in Support of Establishing

Numeric Nutrient Criteria in

St. Joseph Sound,

Clearwater Harbor, and

Boca Ciega Bay

Division of Environmental Assessment and Restoration

Standards and Assessment Section

Florida Department of Environmental Protection

Tallahassee, FL 32399

October 6, 2010Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft ii October 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

.................................................................................................. 19

Harmful Algal Blooms and Fish Kills

............................................................................................ 19

Hypoxia

............................................................................................................................... ....... 19

Other Biological Resources

......................................................................................................... 19



### Water Quality Studies

........................................................................................................... 24

Existing Regional Nutrient Loading Models

................................................................................. 30

Estuary Segments on the 303(d) Impaired Waters List

................................................................ 30



### Numeric Nutrient Criteria Recommendations

........................................................................ 39

References.....................................................................................................................

........ 40Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft iii October 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, Clearwater Harbor, and

Boca Ciega Bay.

............................................................................................................................. 5

Table 2b. Detailed land use breakdown for St. Joseph Sound.

..................................................................... 6

Table 2c. Detailed land use breakdown for Clearwater Harbor.

.................................................................. 6

Table 3. Median/mean values for sampling strata in western Pinellas County, 2004–08. 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, 2004–08.

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

.......................................................... 25

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

Northern Boca Ciega Bay.

........................................................................................................... 35



### List of Figures

Figure 1. Open water assessment segments within Pinellas County. This report discusses Strata

W1–W8 (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 (from Levy 2010).

.......................................................... 8

Figure 3. Annual freshwater flow (millions of gallons per year) from tributaries into Clearwater

Harbor and St. Joseph Sound, 2003–08 (from Levy 2010)............................................................. 9

Figure 4. Annual loading of TP (tons per year) from tributaries to Clearwater Harbor and St.

Joseph Sound, 2003–08 (from Levy 2010).

.................................................................................... 9

Figure 5. Annual loading of TN (tons per year) from tributaries to Clearwater Harbor and St.

Joseph Sound, 2003–08 (from Levy 2010).

.................................................................................. 10

Figure 6. Mapped SAV coverage in St. Joseph Sound, 2008 (data provided by SWFMWD).

...................... 11

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

.................. 12

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

........................ 13

Figure 9. Spatial representation of 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 FWC; maps by Janicki Environmental).

.......................................... 20

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

Harbor (data from angler survey by FWC; maps by Janicki Environmental).

............................. 21Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft iv October 2010 Figure 14. Average shore angler pressure per day for St. Joseph Sound and Clearwater Harbor

(data from angler survey by FWC; maps by Janicki Environmental).

.......................................... 22

Figure 15. Pinellas County bottom DO (mg/L) interpolation map applying kriging using 2004–08

data (Figure 10c in Levy et al. 2009).

.......................................................................................... 26

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

using 2004–08 data (Figure 9c in Levy et al. 2009).

.................................................................... 27

Figure 17. Pinellas County transmissivity percent (at 660 nanometers [nm]) interpolation map

applying kriging using 2004–08 data (Figure 8c in Levy et al. 2009).

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

Figure 18. Mean chla and TN/TP ratios for St. Joseph Sound, 2003–08 (from Levy 2010).

....................... 29

Figure 19. Mean chla and TN/TP ratios for Clearwater Harbor North, 1992–2008 (from Levy

2010).

............................................................................................................................... ........... 29

Figure 20. Mean chla and TN/TP ratios for Clearwater Harbor South, 1992–2008 (from Levy

2010).

............................................................................................................................... ........... 30

Figure 21. Pinellas County waters impaired for chla and Trophic State Index (TSI) (lakes) based

on FDEP 2009 Verified Lists and the 1998 303(d) list for the Group 1 and Group 5 basins

(Figure 3 in Levy et al. 2009).

...................................................................................................... 32

Figure 22. Pinellas County waters impaired for DO based on FDEP 2009 Verified Lists and the

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

................... 33

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

the 1998 303(d) list for the Group 1 and Group 5 basins (Figure 4 in Levy et al. 2009).

............. 34Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 1 October 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 (PCDEM), 1 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.

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 have been collected 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 historical impacts on water quality and SAV.

Impacts from urbanization have been mitigated in recent decades; water clarity is generally good, and

SAV coverage is extensive in these areas. St. Joseph Sound has lower chlorophyll a (chl 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 chl a

. The impaired segments of Clearwater Harbor and Boca Ciega Bay have longer

residence times and less contact with the Gulf of Mexico than the other estuaries in the area,

contributing to higher chl a in those areas, even in the absence of urban influence. Chl 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 governments in the region.

Based on the information in this report, aquatic life use is being fully supported in St. Joseph Sound,

northern Clearwater Harbor, and southern Boca Ciega Bay, and efforts are under way to attain fully

supported aquatic life use in southern Clearwater Harbor and northern Boca Ciega Bay. Tables 1a and

1b provide a checklist of nutrient enrichment symptoms and additional factors, respectively.

Pinellas County has hired Janicki Environmental Inc., a 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 the Working Group completes

its work. 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 chl a target for Lower Tampa Bay (5.1 micrograms per liter [μg/L]) be adopted for southern Boca

Ciega Bay. Once Janicki Environmental 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 PCDEM and the Tampa Bay Estuary Program (TBEP) to develop

numeric nutrient criteria for this region.

1 Contributors to this report include Kelli Levy (PCDEM) and Kris Kaufman (Southwest Florida Water Management District [SWFWMD]).Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 2 October 2010 Table 1a. Checklist of nutrient enrichment symptoms.

‐ = Empty cell/no data

Response Variable Observed

Historically? Observed

Currently? Explanation Source

Low dissolved

oxygen (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 milligrams per liter

(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 chl a

concentrations Yes No Historical loss of SAV likely related to chl 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 Boca Ciega Bay

from 1950 to 1982, and some loss likely

occurred in Clearwater Harbor. SAV

coverage in Boca Ciega Bay rebounded to

80% former coverage in 2008. SAV

coverage increased 16% between 1999 and

2008 in St. Joseph Sound and Clearwater

Harbor. Losses occurred in 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. K. Levy, PCDEM,

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

by Janicki Environmental is ongoing. ‐

Coral/hard

‐ bottom

community

changes or loss Unknown

‐ There is some hard

‐ bottom community in

this area, but it has not been studied. ‐

Impacts to benthic

community Unknown

‐  ‐ ‐

Fish kills Yes, limited

in space and

time ‐ Fish kills have periodically 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, Clearwater Harbor, Boca Ciega Bay

Draft 3 October 2010 Table 1b. Checklist of additional factors.

‐ = Empty cell/no dat

Nutrient Factors Observed? Explanation Source

Increased nutrient loading

or concentrations No Historical increases, but nutrient loading

from humans has decreased in the past

10 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). Table 2a provides physical information about these estuarine areas.

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

the southern (Tables 2b and 2c). 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. PCDEM conducted a forum in March 2007 in which various

stakeholders presented information about the region’s history and resources, and a wealth of

information from that meeting is posted on the PCDEM website (available: http://www.

pinellascounty.org/Environment/pa gesHTML/watershedMngmt/wm8000.html ).

Janicki Environmental submitted a proposal to Pinellas County for the development of a CCMP for

Clearwater Harbor and St. Joseph Sound (Janicki 2009). That proposal was funded, contains a rich

description of the area, and is available on the Pinellas County Water Atlas website. That project is

ongoing and will produce nutrient and chl a targets for this region (available: http://www.

pinellas.wateratlas.usf.edu/news/co mmittees.asp?GROUPID=10050&ACTIVE=1 ).Nutrient C

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1–Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 5 October 2010 Table 2a. Geographic and land use information for St. Joseph Sound, Clearwater Harbor, and Boca

Ciega Bay.

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

SJS = St. Joseph Sound; CWH = Clearwater Harbor

‐ = Empty cell/no data

Information Category Available Data Values Source

Estuarine surface area

(square kilometers

[km 2 ]) ‐ SJS

– 18,000 acres

CWH–10,000 acres Janicki 2009

Watershed area

(km 2 ) 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) SWFWMD

Mean depth

(meters [m]) National

Geophysical

Data Center

(NGDC) Coastal

Relief Model

Clip Shapefile SJS

– 1.49 m

CWH–1.20 m Florida Shelf

Habitat (FLASH)

Map Project, U.S.

Geological Survey

[USGS] 2007)

Volume

(cubic meters [m 3 ]) NGDC Coastal

Relief Model Mean high water volume:

SJS–79,803,504 m 3

CWH–44,389,219 m 3

Mean low water volume:

SJS–43,388,254 m 3

CWH–23,103,029 m 3 FLASH Map Project,

USGS 2007)

Tidal range

(m) Pinellas County

tidal ranges SJS

– 0.369 m above sea level (ASL) to 0.210 m below sea

level (BSL)

CWH–0.357 ASL to 0.192 BSL

Tidal freshwater inflow

(1,000 cubic meters

per day [m 3 d ‐ 1 ]) 2004

– 08 flow

data SJS

– 2,090.765 (in 1,000 m 3 d ‐ 1 ) (includes Smith Bayou

and Klosterman Bayou)

CWH–22,963.81 (in 1,000 m 3 d ‐ 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

(parts per thousand

[ppt]) Salinity 2004

–

08 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 Total

suspended

solids (TSS),

turbidity,

transmissivity,

2004–08 Data in STORET and Water Atlas, summarized in Levy et

al. 2009, Appendix A. Levy et al. 2009

Nutrient data Chl a

, 2004

– 08 Data in STORET and Water Atlas, summarized in Levy et

al. 2009, Appendix A. Levy et al. 2009

Meter data Surface and Data in STORET and Water Atlas, summarized in Levy et Levy et al. 2009Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 6 October 2010 Information Category Available Data Values Source

(DO, temperature,

salinity, pH) bottom

readings for all

sampling

stations, 2004–

08 al. 2009, Appendix A.

Annual and seasonal

loading of total

nitrogen (TN) and total

phosphorus (TP) Load estimates

for 2004–08

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

Branch, Coastal Zones 1 and 4, and McKay Creek) Levy et al. 2009

Geographic

Information System

(GIS) interpolation

maps Salinity,

bottom DO,

chl a

, transmissivity,

2004–08 Data in STORET and Water Atlas, summarized in Levy et

al. 2009, Appendix A. 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.

Land Use Type Acreage %

Agriculture 11,645,481 11.82%

Commercial 6,234,270 6.33%

Natural 19,875,244 20.18%

Open/Disturbed Lands 4,290,692 4.36%

Recreational 5,175,804 5.25%

Reservoirs 1,435,166 1.46%

Residential 44,794,485 45.47%

Transportation 4,301,079 4.37%

Utilities 757,463 0.77%

Table 2c. Detailed land use breakdown for Clearwater Harbor.

Land Use Type Acreage %

Agriculture 436,497 0.28%

Commercial 16,532,290 10.70%

Natural 4,785,361 3.10%

Open Land 1,200,600 0.78%

Recreational 7,875,260 5.10%

Reservoirs 2,177,998 1.41%

Residential 103,587,061 67.02%

Transportation 16,845,320 10.90%

Utilities 1,121,041 0.73%Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 7 October 2010 

### Sources of Nutrients

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

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

estuaries, as well as to Tampa Bay to the east. Eight watersheds 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 land application. 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 10 years.

A new county fertilizer ordinance should reduce nutrient inputs from urban stormwater sources. Pet

waste is considered a large source of fecal coliform bacteria in some 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 TN and TP to St.

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

and 5; Levy 2010).Nutrient C

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Draft 10 October 2010 Figure 5. Annual loading of TN (tons per year) from tributaries to Clearwater Harbor and St. Joseph

Sound, 2003–08 (from Levy 2010).



### Biological Summary

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 contains the greatest coverage of SAV, followed by

Clearwater Harbor and Boca Ciega Bay. Clearwater Harbor and Boca Ciega Bay contain significant areas

that can no longer be colonized by SAV due to dredge

‐ and

‐ fill operations (K. Levy, PCDEM, personal

communication).

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 nearly every 2 years

since. The first SAV estimate (1999) was 13,994 acres, and 17,422 acres of seagrass were 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 in 1950, 1982, and then nearly every 2 years

from 1988 to 2008. There were 10,800 acres of SAV in Boca Ciega Bay 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

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

transects by TBEP in Boca Ciega Bay from 1998 to 2009 (Avery et al. 2010; Appendix B).Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 11 October 2010 Figure 6. Mapped SAV coverage in St. Joseph Sound, 2008 (data provided by SWFMWD).Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 12 October 2010 Figure 7. Mapped SAV coverage in Clearwater Harbor, 2008 (data provided by SWFMWD).Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 13 October 2010 Figure 8. Mapped SAV coverage in Boca Ciega Bay, 2008 (data provided by SWFMWD).Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 14 October 2010 Meyer and Levy (2008) summarized results from PCDEM seagrass monitoring from 1998 to 2007, and

reported that seagrasses are stable. PCDEM sampled fixed transects in St. Joseph Sound, Clearwater

Harbor, and Boca Ciega Bay from 1998 to 2005, and has employed a stratified random sampling design

in St. Joseph Sound and Clearwater Harbor from 2006 to the present. During fixed transect sampling,

the following information was collected: Braun

‐ Blanquet seagrass percent cover, water depth, sediment

composition, seagrass condition, and algae occurrence. Sediment composition was qualitatively

categorized as sand, sandy mud, mud, shelly mud, shelly sand, or hard

‐ bottom. Seagrass condition was

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 midbed and edge of bed, staff recorded shoot density and canopy height. Three

density counts were made using either a 10x10 centimeter (cm) or 25x25 cm square frame. Also, 5

shoot lengths were recorded to the nearest centimeter. Samplers assessed each species independently.

Chl a

, turbidity, Hydrolab®, and LICOR® readings were taken at midbed, edge of bed, and the 2 m depth

contour.

In their report of fixed transect SAV monitoring from 1998 to 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 to 2005 that they attributed to

hurricanes (Meyer and Levy 2008).

SAV data from the first 2 years of stratified random sampling were compared among strata for

Clearwater Harbor North and South and St. Joseph Sound) and depth categories (A

= 0–0.6 m,

B = 0.6–1.2 m, and C = >1.2 m) in Meyer and Levy (2008). SAV covered most of the study area, but mean

abundance was greatest in St. Joseph Sound and least in Clearwater Harbor South. Mean abundance in

Depth Zone A was 77%, significantly higher than the mean for Zone C, 37% (Meyer and Levy 2008). The

3 main species of seagrass were distributed throughout the study area, but Syringodium was

significantly less abundant in Clearwater Harbor North and South than in St. Joseph Sound (Figure 9).

Syringodium also had significantly greater abundance in Depth Zone B (19%) than in Zone A (7%), which

probably explains its greater abundance in deeper St. Joseph Sound. Thalassia abundance was

significantly greater in Zone A (35%) than in B (14%) or C (6%). Halodule was distributed throughout the

region, mainly in Zones A and B, with highest abundance in Clearwater Harbor North and the lowest in

St. Joseph Sound (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 St.

Joseph Sound and in Zone B (Meyer and Levy 2008). Upon visual inspection of the data, Clearwater

Harbor South had more transects with mud substrate (Figure 10).Nutrient C

Draft Figure 9.

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a ndNutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 18 October 2010 Depth to Seagrass Targets

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

Syringodium colonize depths greater than 2 m in St. Joseph Sound and Clearwater Harbor (Figures 9 and

10; Meyer and Levy 2008).

Presence and Frequency of Harmful Algal Blooms

Red tide ( K. brevis ) occurs frequently in this area. Since 2004 it has been found in January–February

2004, February–March 2005, June–October 2005, September–October 2006, and October 2008.

Densities have varied from 1,000 to greater than 1,000,000 cells per liter during these blooms (PCDEM).

Anecdotal accounts of red tide in this area date back to 1844 (Fish and Wildlife Research Institute

[FWRI] historical data, available: http://research.myfwc.com/feat ures/category_main.asp?id=2037 ).

The causes of red tide bloom and proliferation are still somewhat unknown, but the prevailing thought 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 historical and current theories for K. brevis initiation and maintenance, and identified 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 west

‐ central 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 ground water discharge accounts

for the necessary missing nutrients and can initiate and sustain major bloom events off the coast of

west

‐ central 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 (>10 6 cells/L).

Coral or Hard

‐ Bottom Community Structure and Areal Extent

This information has yet to be quantified to date, although the habitat is found in the region. 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 are 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 to 2009), but were also found in theNutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 19 October 2010 northern part of Clearwater Harbor (6 out of 42 occurrences; PCDEM unpublished data). Scallops were

not surveyed in Boca Ciega Bay.

Quantification of Landings from Commercial/Recreational Fisheries

The Florida Fish and Wildlife Conservation Commission (FWC) 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. The results show that fishing is very much a part of the use of

these estuaries (Figures 12 through 14).

Existing Local Biological Indices

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

elsewhere in the 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.

Harmful Algal Blooms and Fish Kills

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

events (available: http://research.myfwc.com/gallery/vie w_category.asp?catid=1357&subcatid=3227 ).

Hypoxia

Preliminary information suggests that hypoxia does not appear to be a significant issue in this area.

Other Biological Resources

Mangrove islands, oyster bars, and mudflats comprise important habitat for more than 7,000 breeding

pairs of birds in Clearwater Harbor (Audubon of Florida 2009), supported by the resident fishery.Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 20 October 2010 Figure 12. Average charter angler pressure per day for St. Joseph Sound and Clearwater Harbor (data

from angler survey by FWC; maps by Janicki Environmental).Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 21 October 2010 Figure 13. Average private boat angler pressure per day for St. Joseph Sound and Clearwater Harbor

(data from angler survey by FWC; maps by Janicki Environmental).Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 22 October 2010 Figure 14. Average shore angler pressure per day for St. Joseph Sound and Clearwater Harbor (data

from angler survey by FWC; maps by Janicki Environmental).Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 23 October 2010Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 24 October 2010 

### Water Quality Studies

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

period, and those results are reported in this section. The PCDEM sampling program during this period

was a probabilistic design in which 32 to 36 sites in each unit (as shown in Figure 1) were sampled. Four

samples were collected during each of the 8 to 9 sampling events. Water samples were collected and

analyzed per FDEP Standard Operating Procedures (SOPs), with analysis done at a National

Environmental Laboratory Accreditation Conference (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 are used to develop systemwide loading estimates. PCDEM has

water quality data for Pinellas County waters from 1999 to 2003 from a fixed station monitoring

program (available: http://www.pinellas.wateratlas.usf.edu/ ).

Spatial interpolation analysis of PCDEM data from 2004 to 2008 shows the spatial distribution of DO,

chl a

, and transmissivity in open waters of Pinellas County (Figures 15 through 17). Southern Clearwater

Harbor, the Narrows, and North and Central Boca Ciega Bay (W3 through 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 chl a during either the wet or dry season (Levy et al. 2009). Chl 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), chl a concentrations are low (< 4 μg/L) in St. Joseph Sound

and moderate in Clearwater Harbor (4 to 11 μg/L) and Boca Ciega Bay (6 to 15 μg/L) (Figure 16). Mean

chl 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 TN to TP (Figures 18

through 20). Long

‐ term chl a data are still being evaluated for Boca Ciega Bay, and for TN and TP in all

areas. Tables 3 and 4 list the median/mean and maximum/minimum values, respectively, for sampling

strata in western Pinellas County from 2004 to 2008.

The lower DO and higher chl a in the middle part of western Pinellas County (W3, W4, W5, W6) are likely

due to larger watersheds feeding into those estuarine areas and the greater restriction 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, 2004–08. Strata as in

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

NTU = Nephelometric turbidity unit

Site Bottom DO

(mg/L) Chl 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 / 83.18Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 25 October 2010 Table 4. Maximum/minimum values for sampling strata in western Pinellas County, 2004–08. Strata

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

Site Bottom DO

(mg/L) Chl 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 / 43.48Nutrient C

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2 010Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 29 October 2010 Figure 18. Mean chla and TN/TP ratios for St. Joseph Sound, 2003–08 (from Levy 2010).

Figure 19. Mean chla and TN/TP ratios for Clearwater Harbor North, 1992–2008 (from Levy 2010).Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 30 October 2010 Figure 20. Mean chla and TN/TP ratios for Clearwater Harbor South, 1992–2008 (from Levy 2010).

Existing Regional Nutrient Loading Models

Janicki Environmental (2008) developed loading models for the Tampa Bay Estuary and is developing

loading models for this region under the CCMP (Janicki 2009).

Estuary Segments on the 303(d) Impaired Waters List

Several estuarine waterbodies are on the 303(d) list for chl a

, DO, or fecal coliform bacteria (Figures 21

through 23). Table 5 lists the segments with waterbody identification (WBID) numbers 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 urban areas; none of the open estuary areas are impaired. Three WBIDs

are listed for fecal coliform exceedances, and five are listed for DO and nutrients (chl a ) (Table 5).

Total Maximum Daily Loads (TMDLs) have been established for fecal coliforms in tidal portions of

Klosterman Bayou, which empties to St. Joseph Sound (Albright 2008), and in 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 (MST) and pathogen

‐ detection methods for use under Gulf of Mexico

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

the status of U.S. Environmental Protection Agency (EPA) recreational water quality criteria (GOMA

2009). The workgroup expressed concern that the EPA recreational criteria were derived in places that

do not represent Gulf of Mexico conditions, and that the use of fecal indicators was not appropriate for

waters primarily influenced by animal sources. Areas in the Gulf of Mexico for which they thought theNutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 31 October 2010 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 assuming that the presence of these bacteria automatically indicates the presence of

anthropogenic nutrients.Nutrient C

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2 010 eNutrientCriteriaTechnicalSupportDocumentSt.JosephSound,ClearwaterHarbor,BocaCiegaBayDraft35October2010Table5.VerifiedimpairedwaterbodiesthatemptyintoSt.JosephSound,ClearwaterHarbor,orNorthernBocaCiegaBay.WaterbodyID(WBID)WaterbodySegmentParametersAssessedUsingthe2001ImpairedSurfaceWatersRule(IWR)ConcentrationCausingImpairmentPriorityforTMDLDevelopmentComments(#Exceedances/#Samples)PP=PlanningPeriodVP=VerifiedPeriod41508KLOSTERMANBAYOUColiform(FecalColiform)>400coloniesper100milliliters(colonies/100mL)HighPP=6/57;VP=7/371508KLOSTERMANBAYOUDO<4.0mg/LHighPP=71/350;VP=49/231Verifiedimpaired.Nutrientswereidentifiedascausativepollutantbasedonchladata/nutrientimpairmentverification.1508KLOSTERMANBAYOUNutrients(chlaandHistoricchla[histchla])MedianTN=1.665mg/LHighPP=Potentiallyimpaired;VP=Verifiedimpaired.Annualaveragechlavaluesexceeded11g/Lin1999–2005,andvalueswere27.9,32.44,30.02,22.67,49.07,38.14and45.29g/L,respectively.Forhistoricallisting,annualaveragechlavaluesinverifiedperiodexceededminimumhistoricalannualaveragevalueof21.12g/Lfor1990–94bymorethan50%in2004(38.14g/L)and2005(45.28g/L).NislimitingnutrientbasedonmedianTN/TPratioof3.16(133values).VerifiedperiodTNmedian=1.665(134values),TPmedian=0.59mg/L(150values),andbiochemicaloxygendemand(BOD)median=3.25mg/L(106values).1538CURLEWCREEKTIDALDO<4.0mg/LHighPP=56/350;VP=28/71Verifiedimpaired.Nutrientswereidentifiedascausativepollutantbasedonchladata/nutrientimpairmentverification.1538CURLEWCREEKTIDALNutrients(chla)MedianTN=1.65mg/LHighPP=Nodata;VP=33/62Verifiedimpaired.AnnualaverageChlavaluesexceeded11g/Linallyearsfrom1999–2004,andvalueswere27.29,32.09,35.35,15.15,and24.51g/L,respectively.NislimitingnutrientbasedonmedianTN/TPratioof7.9(67values).VerifiedperiodTNmedian=1.65mg/L(68values),TPmedian=0.22mg/L(67values),andBODmedian=2.6mg/L(47values).1556CEDARCREEKDO<4.0mg/LHighPP=64/221;VP=42/82Verifiedimpaired.NutrientswereNutrientCriteriaTechnicalSupportDocumentSt.JosephSound,ClearwaterHarbor,BocaCiegaBayDraft36October2010WaterbodyID(WBID)WaterbodySegmentParametersAssessedUsingthe2001ImpairedSurfaceWatersRule(IWR)ConcentrationCausingImpairmentPriorityforTMDLDevelopmentComments(#Exceedances/#Samples)PP=PlanningPeriodVP=VerifiedPeriod4(TIDAL)identifiedascausativepollutantbasedonchladata/nutrientimpairmentverification.1556CEDARCREEK(TIDAL)Nutrients(chla)MedianTN=1.05mg/LHighPP=Potentiallyimpaired;VP=Verifiedimpaired.Annualaveragechlavaluesexceeded11g/Lin1999–2005,andvalueswere13.91,31.74,12.85,23.44,3.363,11.26and5.108g/L,respectively.NislimitingnutrientbasedonmedianTN/TPratioof6.89(69values).VerifiedperiodTNmedian=1.05mg/L(69values),TPmedian=0.15mg/L(77values),andBODmedian=3mg/L(47values).1567STEVENSONCREEK(TIDALSEGMENT)DO<4.0mg/LHighPP=141/408;VP=77/212Verifiedimpaired.Nutrientswereidentifiedascausativepollutantbasedonchladata/nutrientimpairmentverification.1567STEVENSONCREEK(TIDALSEGMENT)Nutrients(chla)MedianTN=1.29mg/LHighPP=Potentiallyimpaired;VP=Verifiedimpaired.Annualaveragechlavaluesexceeded11g/Lin1999–2002and2004,andvalueswere16.08,32.74,59.37,24.75and42.81g/L,respectively.NislimitingnutrientbasedonmedianTN/TPratioof5.79(116values).VerifiedperiodTNmedian=1.29mg/L(117values),TPmedian=0.22mg/L(121values),andBODmedian=2mg/L(92values).1633MCKAYCREEK(TIDAL)Coliform(FecalColiform)>400colonies/100mLHighPP=34/36;VP=1/11;SufficientPP/VPdatatoassess.PPandmostrecent20samples(9/20)triggerVerifiedList;assessmentbasedonperiodofrecorddata.1633MCKAYCREEK(TIDAL)DO<4.0mg/LHighPP=119/572;VP=39/60Verifiedimpaired.Nutrientswereidentifiedascausativepollutantbasedonchladata/nutrientimpairmentverification.1633MCKAYCREEK(TIDAL)Nutrients(chla)MedianTN=1.04mg/LHighPP=Nodata;VP=23/58Verifiedimpaired.Annualaveragechlavaluesexceeded11g/Lin1999–2000,2002,and2004,andvalueswere12.22,13.85,11.48and21.52g/L,respectively.NislimitingnutrientbasedonTN/TPratioof5.05(56values).VerifiedperiodTNmedian=1.04mg/L(56values),TPmedian=0.2(61values),andBODmedian=2mg/L(48).NutrientCriteriaTechnicalSupportDocumentSt.JosephSound,ClearwaterHarbor,BocaCiegaBayDraft37October2010WaterbodyID(WBID)WaterbodySegmentParametersAssessedUsingthe2001ImpairedSurfaceWatersRule(IWR)ConcentrationCausingImpairmentPriorityforTMDLDevelopmentComments(#Exceedances/#Samples)PP=PlanningPeriodVP=VerifiedPeriod41641CROSSCANAL(SOUTH)Coliform(FecalColiform)>400colonies/100mLLowPP=16/36;VP=16/40.1641CROSSCANAL(SOUTH)DO<4.0mg/LMediumPP=75/398;VP=73/315VerifiedImpaired.Nutrientswereidentifiedascausativepollutantbasedonchladata/nutrientimpairmentverification.1641CROSSCANAL(SOUTH)Nutrients(chla)MedianTN=1.11mg/LMediumPP=Potentiallyimpaired;VP=Verifiedimpaired.Annualaveragechlavaluesexceeded11g/Lin1999and2001–2005,andvalueswere17.75,14.84,12.34,18.95,14.17and17.38g/L,respectively.NislimitingnutrientbasedonmedianTN/TPratioof6.98(150values).VerifiedperiodTNmedian=1.11mg/L(152values),TPmedian=0.16mg/L(159values),andBODmedian=2mg/L(123values).1662PINELLASPARKDITCHNO1(TIDALSEGMENT)Coliform(FecalColiform)>400colonies/100mLHighPP=8/12;VP=2/10;SufficientPP/VPdatatoassess.PPand"PP+VP"sampleexceedanceratestriggerVerifiedList(PP+VP=10/22),andperiodofrecorddatashowshowsmultiplepost‐VPexceedancesin2006.Areaishighlydeveloped.Assessmentbasedonperiodofrecorddata.1662PINELLASPARKDITCHNO1(TIDALSEGMENT)DO<4.0mg/LHighPP=6/23;VP=3/11;PP+VPprovidesufficientdatatoassess.CombinedPP+VPdatasetyields9/22,andresultsformostrecent20samples=8/20.Bothexceedthresholdforverification.Areaishighlydeveloped.Assessmentbasedonperiodofrecorddata.1701BEARCREEKColiform(FecalColiform)>400colonies/100mLLowPP=31/37;VP=Nodata;SufficientPPdata(all1994–96)toassess.Areahasbeenlargelybuiltoutformanyyears.Assessmentbasedonperiodofrecorddata.1701BEARCREEKDO<5.0mg/LMediumPP=102/346;VP=58/171Verifiedimpaired.ThereissufficientnumberofDOviolationstoplaceWBIDonVerifiedListforDO.However,unabletolinklowDOtocausativepollutant(BODornutrients).1716CLAMBAYOUDO<4.0mg/LHighPP=2/4;VP=5/8Verifiedimpaired.NutrientswereidentifiedNutrientCriteriaTechnicalSupportDocumentSt.JosephSound,ClearwaterHarbor,BocaCiegaBayDraft38October2010WaterbodyID(WBID)WaterbodySegmentParametersAssessedUsingthe2001ImpairedSurfaceWatersRule(IWR)ConcentrationCausingImpairmentPriorityforTMDLDevelopmentComments(#Exceedances/#Samples)PP=PlanningPeriodVP=VerifiedPeriod4DRAIN(TIDAL)ascausativepollutant.VerifiedperiodTNmedian=1.26mg/L(5values),TPmedian=0.14(5values),andBODmedian=5mg/L(7values).1618CLONGBAYOU/CROSSBAYOUDO<4.0mg/LMediumPP=17/67;VP=43/210Verifiedimpaired.Nutrientswereidentifiedascausativepollutantbasedonchladata/nutrientimpairmentverification.1618CLONGBAYOU/CROSSBAYOUNutrients(chla)MedianTN=0.96mg/LMediumPP=Potentiallyimpaired;VP=Verifiedimpaired.Annualaveragechlavaluesexceeded11g/Lin2003–05,andvalueswere19.92,11.25,and16.73g/L,respectively.NislimitingnutrientbasedonmedianTN/TPratioof6.26(118values).VerifiedperiodTNmedian=0.96mg/L(119values),TPmedian=0.17mg/L(114values),BODmedian=nodata.1668ESTJOECREEK(TIDALSEGMENT)DO<4.0mg/LMediumPP=45/197;VP=33/122VerifiedImpaired.NutrientsandBODwereidentifiedascausativepollutantbasedonchladata/nutrientimpairmentverification.1668ESTJOECREEK(TIDALSEGMENT)Nutrients(chlaandhistchla)MedianTN=1.14mg/LMediumPP=Potentiallyimpaired;VP=Verifiedimpaired.Annualaveragechlavaluesexceeded11g/Lin1999–2002and2004,andvalueswere40.48,26.65,21.1,23.06,and23.87g/L,respectively.Forhistoricallisting,annualaveragechlavaluesinverifiedperiodexceededminimumhistoricalannualaveragevalueof16.31g/Lfor1990–94bymorethan50%in2consecutiveyearsin1999(40.48g/L)and2000(26.65g/L).NislimitingnutrientbasedonmedianTN/TPratioof6(62values).VerifiedperiodTNmedian=1.14mg/L(63values),TPmedian=0.18mg/L(66values),andBODmedian=3.05mg/L(52BODvalues).Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 39 October 2010 

### 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, and

the 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. TBNMC has proposed a chl 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 PCDEM and TBEP to

develop numeric nutrient criteria for this region.Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 40 October 2010 

### References

Albright, J. 2008. Fecal coliform TMDL for the Klosterman Bayou tidal segment, WBID 1508. Tallahassee,

FL: Florida Department of Environmental Protection. Available: http://www.dep.state.fl.us/

water/tmdl/docs/tmdls/final/gp5/klosterman

‐ bayou

‐ tidal

‐ fc_tmdl.pdf

.

Audubon of Florida. 2009. Birds and Birding: Florida’s imperiled birds. Available:

http://fl.audubon.org/birds_imperiled_colonial.html

.

Avery, W.M, K.B. Hennenfent, J.O.R. Johansson, and J.J. Pacowta. 2010. Draft Tampa Bay Interagency

Seagrass Monitoring Program training and field manual. Submitted to the Tampa Bay Estuary

Program, July 1, 2010. Bay Study Group, City of Tampa. Available: http://www.tbeptech.org/

DATA/GIS/Seagrass/COT_Draft_Seagrass_Transect_Training_Document.pdf

.

Boehm, A.B., N.J. Ashbold, J.M. Colford, Jr., L.E. Dunbar, L.E. Fleming, and M.A. Gold et al. 2009. A sea

change ahead for recreational water quality criteria. Journal of Water and Health 07.1: 9

‐ 20.

Gulf of Mexico Alliance (GOMA). 2009. Comments regarding pending EPA Clean Water Act,

Recreational Water Quality Criteria. Prepared for the U.S. Environmental Protection Agency

Stakeholders Workshop, October 6

‐ 7, 2009, Chicago, IL.

Hamm, D.C. 1975. Benthic algae of the Anclote River Estuary. Masters thesis, University of South

Florida.

Hu, C., F. Muller

‐ Karger, and P.W. Swarzenski. 2006. Hurricanes, submarine groundwater discharge and

west Florida's red tides. Geophys. Res. Lett. 33.

Janicki Environmental, Inc. 2008. Estimates of total nitrogen, total phosphorus, total suspended solids,

and biochemical oxygen demand Loadings to Tampa Bay, Florida: 2004–2007. Prepared for the

Florida Department of Environmental Protection, Tallahassee, FL.

———. 2009. Development of a Comprehensive Conservation Management Plan for Clearwater Harbor

and St. Joseph Sound. Submitted to Pinellas County, March 31, 2009. Available: http://www.

pinellas.wateratlas.usf.edu/news/co mmittees.asp?GROUPID=10050&ACTIVE=1

.

Johansson, J.O.R. 1975. Phytoplankton standing crop in the Anclote River estuary. Masters thesis,

University of South Florida.

Kurisko, P.C. 2008. Fecal coliform TMDL for Saint Joes Creek, WBID 1668A. Tallahassee, FL: Florida

Department of Environmental Protection. Available: http://www.dep.state. fl.us/water/tmdl/

docs/tmdls/final/gp5/st

‐ joes

‐ crk

‐ fc_tmdl.pdf

.

Levy, K.H. 2010. Presentation at numeric nutrient criteria development public meeting in St. Petersburg,

February 4, 2010. Pinellas County Department of Environmental Management.

Levy, K.H., M. Flock, and R. Burnes. 2009. Ambient Monitoring Program annual report 2004–2008.

Pinellas County Environmental Management Water Resources, Watershed Management

Division. Available: http://www.pinellascounty.org/Environment/pagesHTML/

waterResources/wr1000.html

.

Meyer, C.A. and K.H. Levy. 2008. Pinellas County Seagrass Resource Assessment and Monitoring

Program status report 1998

‐ 2007. Pinellas County Environmental Management Water

Resources. Available: http://www.pinellascounty.or g/Environment/pagesHTML/

waterResources/wr6000.html

.Nutrient Criteria Technical Support Document St. Joseph Sound, Clearwater Harbor, Boca Ciega Bay

Draft 41 October 2010 Vargo, G.A. 2009. A brief summary of the physiology and ecology of Karenia brevis Davis (G. Hansen

and Moestrup comb. nov.) red tides on the West Florida Shelf and of hypotheses posed for their

initiation, growth, maintenance, and termination. Harmful Algae 8, 573

‐ 584.

Vargo G.A., C.A. Heil, D.N. Ault, and M.B. Neely. 2004. Four Karenia brevis blooms: A comparative

analysis. In: K.A. Steidinger, J.H. Landsberg, C.R. Tomas, and G.A. Vargo (Eds.), Harmful algae

2002 (St. Petersburg, FL: Florida Fish and Wildlife Conservation Commission, Florida Institute of

Oceanography and Intergovernmental Oceanographic Commission of the United Nations

Educational, Scientific and Cultural Organization [UNESCO], pp. 14–16).

Vargo, G.A., C.A. Heil, K.A. Fanning, L.K. Dixon, M.B. Neely, and K.A. Lester et al. 2008. Nutrient

availability in support of Karenia brevis blooms on the central West Florida Shelf: What keeps

Karenia blooming? Cont. Shelf Res. 28, 73–98.

## APPENDIX B

. Implementation Issues:

Targets, Thresholds, Type I Error and

Compliance Assessment for Nu meric Nutrient Criteria

Using the Reference Period A pproach

Background

Site specific numeric nutrient criteria for indivi dual estuarine water bodies in southwest Florida

from Saint Joseph Sound in Clearwater, Florida th rough Estero Bay, Florida are being proposed as

alternatives to the application of regional or stat e wide model based standards. These site specific

criteria rely on the identification of a respons e endpoint and the endpoi nt defined for these

estuaries has been defined as a threshold chlorophyll a concentration in all cases. The temporal

scale has been defined as yearly; therefore, the a ssessment statistic is an annual average chlorophyll

a concentration. Generally, the geometric annual average is used; however, in cases where the data

are first averaged monthly, a simple arithmetic average is used. These threshold chlorophyll a

concentrations for all estuaries have been identifie d using a reference peri od approach. Subsequent

numeric nutrient criteria have been developed either by applying a stressor response relationship

between nutrients and chlorophyll a concentrations, or by simply calculating an average of the

annual averages of the reference period.

The reference period approach re lies on the identification of a period in time when these estuarine

water bodies were sufficient to support full aquatic life uses. The overarching logic is that, provided

a reliable stressor response model cannot be developed to accurately predict that point at which a

system would no longer meet its full aquatic life use, water quality conditions during of a period in

time when that waterbody was meeting its designat ed use would be protecti ve of full aquatic life

uses. For example, the estuarine open water segmen t of Saint Joseph Sound has been meeting full

aquatic life uses according to FDEP water quality standards and the Impaired Waters Rule since

2003. This means that chlorophyll a concentrations (Chla) have been below an annual average of

11 μg/L and dissolved oxygen concen trations (DO) have been above 4 mg/L in at least 90% of the

samples. These “endpoints” (i.e., Chla and DO) are typical indicators used to assess the health of

estuarine waters. The period of time between 2003 and 2009 was therefore chosen as the reference

period for Saint Joseph Sound.

To establish numeric nutrient criteria using the re ference period approach, a period of time would

be identified when the waterbody was meeting its designated use, parameters would be defined to

characterize the population of wate r quality values for chlorophyll a , total nitrogen (TN) and total

phosphorus (TP) during that time, and then threshold values would be defined to represent a

deviation from the expected condition of the reference period. The following paragraphs provide

an example of how targets, thresholds and the type I error, and compliance assessment procedures

have been established using the reference period approach.

Reference Period Example

To begin this example, a hypothetical reference pe riod distribution of chlorophyll a concentrations

was generated. Chlorophyll a concentrations in estuaries typica lly exhibit “lognormal” distributioncharacte r

becomes

lognorm a

and a st a

in Figur e

correspo n

Protectio

geometri c chloroph

hypothet

Given th

product o

from the

obtain t h

selecting

close to t

know th a

annual a v

of annua

expected r istics. This

normally d

a l distributio

ndard devia t

e 1. Once t

n ding to the

n (FDEP) a n

c means as yll a, we n o

i cal evaluati o

e theoretica

o f a typical

distribution

h e geometri c

12 samples

t he overall a

a t variability

v erages fro m l averages i s

.

F i implies that

d istributed w

n of chloro p

t ion of 4.49

he data are

normal dist r

n d the Envir o regulatory

o w consider

o n and back

l distributio n

monitoring p

of log valu e

c mean. F

and calcula

a verage of th

will exist d u

m the referen c

s centered o

i gure 1. Sim u when a nat u

w hich confo r

p hyll a con c μg/L. This d

natural lo g

r ibution (Fig u

o nmental P r

statistics f o the log tra n

transform t h

n of Figure

p rogram. F o

e s, and cal c

u rther, we c ting the ave r

e re f erence

u e to sampli n

c e period di s

n a value v e

u lated distrib u u ral log tran s

r ms to most

c entrations w

istribution c o

g transforme d

u re 2). Since

r otection A g

o r paramete r

n sformed val

h e averages t o

2, we can g

o r example,

c ulate an av e

c an repeat

r age of the l

period sinc e

n g. For exa m

s tribution. A

e ry close to

u tion of chlor o s formation i s

t parametric

w as simulate

o mposed of

d , the distri

the Florida

g ency (EPA)

r s with log n

ues to repr e

o obtain the

g enerate an n

we can ran d

e rage and b a this experi m og values. W

e it is a rand o

m ple, in Fig u

s can be se e

the overall

o phyll a con c s applied to t

statistical t e d using a m

10000 obs e

bution bec o

Department

have propo

n ormal dist r

e sent the da t

geometric m

n ual averag e domly selec

a ck transfor m

m ent many

W e expect e a

om sub-sam

u re 3, we h a

e n in Figure 3

average in F

c entrations. t he distribut i

e sts. Theref o

m ean of 6.7 5

e rvations is s h

o mes bell s h

of Environ m sed using a n

r ibutions su c

t a underlyin g

m eans.

e s to simula t

c t 12 observ a

m that aver a

times, each

a ch average

ple, howev e

a ve generate d

3 , the distri b

F igure 2 wh i on, it

o re, a

5 μg/L

h own

h aped

m ental

nnual

c h as

g this

t e the

a tions

a ge to

time

to be

e r, we

d 100

b ution

ich isFig u

Figure 3

. re 2. Distrib u

Distributio n tion of the n a

of 100 annu a tural log tra n

l averages o f sformed val u

f the log tran s

per year. u es of the si m

s formed chlo r ulated distri b

ophyll value s ution above.

using 12 sa m plesTo deriv e

3. This d i

Targets a

Once th e

targets a n

The refe r

geometri c

to the r e

Howeve r populati o

can be c

averages

value to

was fro m Using th e

standard

deviatio n

distributi o

exceed t o

distributi o e the geome t

i stribution is

Figure 4. Ge o

a nd Threshol

e geometric m

n d threshol d

r ence perio d

c means. Th a

e ference per i

r , it can be

o n ranges b e

c onsidered a

of the refer e

represent a n

m the same

e z table of

deviation o f

n of the pop u

o n that defi n

o reject the

o n that thre s t ric annual a

shown in Fi g

o metric mea n

ds

m eans have

d s for this th e

d target for

a t is, 5.947 μ

i od conditi o

seen from F

e tween 3.9 μ

a populatio n

e nce period.

n annual av e population a

standard st a

f the distrib u

u lation of ge o

n es with 95 %

hypothesis

s hold value e a verages, w e

g ure 4.

n s taken from

been calcul a

e oretical refe

this distribu t

μ g/L is our g o

o n we ident i

F igure 4 tha t

μ g/L and 8.3

n of values

Based on n

e rage above

a s the refer e

a tistical tests

,

u tion in Fig u

o metric mea

% confidenc e

that it bel o

e quals 7.59 μ e simply bac k

the simulate d

a ted we hav e

rence perio d

t ion can be

o al for the w

fied as bei n

t the distrib u μg/L. Ther e that repres e

n ormal distri

which we w

e nce period

, only 5% o

u re 4 woul d

ns. Therefo r

e what valu e

o nged to th e

μ g/L. k transform t

d chlorophyll

e all the inf o

d distributio n

defined as t

w ater body t o

n g indicativ e

u tion of ann

e fore, the di s

e nt the ex p

bution theo r

w ould reject

distribution

o f a normal d

d lie above t

r e, a thresh o

e a given ge

e reference t he annual a

concentratio n

o rmation ne c

n

.

t he overall a

o ensure that

e of full aq u

ual geomet r

s tribution of

p ected distri b

r y, we can a the hypoth e

of annual g

d istribution

t he mean+ 1

o ld can be c o

e ometric me a

period distr i a verages of F

n s above.

c essary to de v

a verage of a

it remains s i

u atic life su p

r ic means f o

geometric m

b ution of a n

a ssign a thre

e sis that the

g eometric m

with a mea n

1 .65*the sta n

o nstructed f o

a n would n e

i bution. Fo F igure

v elop

a ll the

i milar

p port.

o r this

m eans

n nual

e shold

value

m eans.

n and

n dard

o r this

e ed to

r thisThe threshold value provides a level of certainty that a future single geometric mean value (i.e. a

sample) is not declared to exceed the reference distribution simply due to sampling. As was

demonstrated above, we know that some portion of the reference distribution values will be above

the target value. In fact, nearly 50% of the annual geometric means will be higher than the target

. However, only 5% of the values will be higher than the threshold value of 7.59 μg/L due to

chance. This construct defines what is known as the Type I error rate or False Positive rate

. That

is, we are willing to accept that 1 in 20 times we ma y get a value that is higher than 7.59 μg/L that

still belongs to the reference period distribution. As was seen in Figure 4, 5% of the values did

exceed 7.59 μg/L even though we know the entire population of values.

Therefore, the type I error rate is a value that is selected base d on judgment and while 5% is

typically used, there is no definitive rationale fo r 5% versus 1% or 10%. If we wish to be more

conservative, we would select a lower type I erro r rate by choosing a larger value (e.g., 1.96) to

multiple against the standard deviation to minimize the potential for falsely declaring that a value

was different from the reference distribution. If we have reason to believe that the water body may

not fully meet its designated use at values at the higher end of the reference distribution, one could

select a higher type I error rate which in turn wo uld equate to a smaller z score to multiply by the

standard deviation (e.g., 1). For example, selectin g 1 standard deviation equates to a type 1 error

rate of 16%. However, the type 1 error rate doe s have implications on the compliance assessment.

Compliance Assessment

Now that the definition of targets, thresholds, and type 1 error has been identified, there is another

consideration that must be taken into acc ount when evaluating criteria exceedances. The

exceedance frequency for an exceedance due to chance is defined by the type 1 error rate as

described above. However, the exceedance frequency and duration component also must be

established to allow for some anomalous condition unrelated to anthropogeni c activity such as an

El Niño, or La Niña cycles. There is substantial evidence that these meteorological anomalies can

result in higher chlorophyll a concentrations (e.g., Morrison et al. 2006, Sherwood 2010).

Therefore, this type of exceedance is different from the type I error described above. Since we have

previously defined the type I error rate, we have already made the choice as to the false positive

rate we are willing to accept. The implementati on question is now posed to ask “what is the

frequency of exceedances and assessment cycle that allows for occurrences unrelated to local

anthropogenic activities but remain s sensitive to capturing population deviations from the reference

period due indicative of human adverse effects?”

To address this question the Multivariate ENSO I ndex calculated by Klaus Wolter of the National

Oceanic and Atmospheric Administration (see Wolter and Timlin 1993) was used as described in

several implementation documents produced by Janicki Environmental regarding implementation

of numeric nutrient criteria (Janicki Environmental, In c. 2011a-c). It is easy to see in Figure 5 that

when El Niño or La Niña events occur they tend to last more than a single year. In fact, it’s quite

possible for many of the single events to cr oss a calendar year. Further information on the

frequency and duration of ENSO events can be found at: http://www.esrl.noaa.gov/psd/enso/mei/Figur e

Based o n

result in

one yea r

allowan c

2 exceed

It is poss

such tha t

exceeda n

one mig h

to a nat u pursued

threshol d

criteria a r

of the 2 i e 5. Classific a

n this analys

higher annu

r in a 5 ye a

e as an exc e

ances in a 5

i ble that the

t both the p r

n ce occurs d

h t calculate t

u ral anomal y as the impl

d values wit h

r e inextrica b

n 5 implem e a tion of El Ni ñ

is, it makes

al geometri c

a r cycle as

e edance freq

year assess m

type I error

r obability o f

ue to anom a he union pr o

y . This was

ementation

h known ty p

b ly linked an d

e ntation rule ñ o and La Ni ñ

sense to al l

c average th a

is currentl y uency in a f i

m ent cycle.

rate and th e

f an exceed a

a lous condit

o bability of a

beyond the

process is r

p e 1 error r a

d should no t

is provided ñ a events as d e

l ow for the

a n the refer e

y proposed b

ve year ass e

e probability

a nce occurri n

ions could b

a n exceedan

scope of t h

r efined. Bec a

a tes, the crit

t be separat e

in Janicki En e scribed in J a

potential th a

e nce period

by FDEP.

e ssment cycl e

of an anom a

n g by chan c

b e integrate d

ce due to c h

h is memora n

a use the pr o

eria and th e

e d. Further i n

n vironmental a nicki Enviro n

a t an anom a

threshold v a

Therefore t h

e is to allow

a lous event

c e and the p

d . That is, o v

h ance and a n

n dum but o

o posed crit e

e 2 in 5 ye a

n formation s

(2011). n mental 2011 a

a lous event c

a lue in mor e

h e recomm e

for no mor e

can be calc u

p robability t h

v er a 5 yea r

n exceedanc e ne that mig

e ria are bas e

a r implemen t

upporting t h a

.

c ould

e than

e nded

e than

u lated

h at an

cycle

e due

ht be

e d on

t ation

h e use

### References

Janicki Environmental, Inc. 2011a. Sarasota Bay Numeric Nutrient Criteria: Task 4 -

Implementation Issues. Letter Memorandum Prepared for Sarasota Bay Estuary Program. Sarasota,

Florida

Janicki Environmental, Inc. 2011b. Charlotte Ha rbor Numeric Nutrient Criteria: Implementation

Issues. Letter Memorandum Prepared for Charlott e Harbor Estuary Program. Ft. Myers, Florida

Janicki Environmental, Inc. 2011c. Tampa Bay Numeric Nutrient Criteria: Task 4 –

Implementation Issues. Letter Memorandum. Prepared for: Tampa Bay Estuary Program.

Morrison, G., E.T. Sherwood, R. Boler, and J. Barron. 2006. Variations in water clarity and

chlorophyll a in Tampa Bay, Florida, in response to annual rainfall, 1985-2004. Estuaries and

Coasts. 29:926-931.

Sherwood, E.T. 2010. 2009 Tamp a Bay Water Quality Assessment. 2010. Technical Report #02-10

of the Tampa Bay Estuary Program. Prepared by the Tampa Bay Estuary Program.

Wolter, K., and M.S. Timlin, 1993: Monitoring ENSO in COADS with a seasonally adjusted

principal component index. Proc. of the 17th Climate Diagnostics Workshop , Norman, OK,

NOAA/NMC/CAC, NSSL, Oklahoma Clim. Survey, CIMMS and the School of Meteor., Univ.

of Oklahoma, 52-57.

Download PDF

. http://www.esrl.noaa.gov/psd/pe ople/klaus.wolter/MEI/#ref_wt1