# NUMERIC NUTRIENT CRITERIA FOR SARASOTA BAY

Prepared for: Sarasota Bay Estuary Program

Pre p ared b y : Janicki Environmental, Inc.

August 2010

# ACKNOWLEDGMENTS This report benefited from critical input from the Sarasota Bay Estuary Program staff and the Technical Advisory Committee. Particular suppo rt was provided by Mark Alderson and Dr. Jay Leverone. The water quality subcommittee also pr ovided continued input during this project including: Lizanne Garcia, Kris Kaufman, Veronica Cr aw – Southwest Florida Water Management District Charles Kovach, Pete Wenner – Florida Department of Environmental Protection Rob Brown, Greg Blanchard – Manatee County Jack Merriam, John Ryan, Jon Perry – Sarasota County Gary Serviss – VHB, Inc. Amber Whittle – Florida Fish and Wildlife Conservation Commission David Tomasko – PBS&J Kellie Dixon – Mote Marine Laboratory We would also like to acknowledge the very important input provided by Jones Edmunds & Associates, Inc. for their contributions to the SIMP LE model application with critical work provided by Brett Cunningham, Jason Icerman, Suzi Kaufmann, and Lisa Foster.

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# EXECUTIVE SUMMARY One of the major objectives of the Clean Water Act (CWA) is to restore and maintain the chemical, physical and biological integrity of the Nation’s wa ters to provide “water quality which provides for the protection and propagati on of fish, shellfish, and wildlife and provides for recreation in and on the water”. On January 14, 2009 the U.S. Envi ronmental Protection Agency (USEPA) determined under the CWA section 303(4)(B) that new or revi sed water quality standards expressed as numeric nutrient criteria (NNC) are necessary to meet the re quirements of the CWA in the State of Florida. These criteria are numeric limits on the amount of phosphorus and nitrogen that would be allowed in Florida’s waters. NNC will provide baselines against which to measure environmental progress, to facilitate the writing of protective NPDES permits, and to develop defensible TMDLs. The original USEPA schedule for proposed estuarine and coastal water criteria was January 2011. This schedule has been recently modified a nd now requires USEPA to propose estuarine and coastal waters nutrient criteria and downstream protective values in Florida by November 14, 2011. This revised schedule will allow more time for peer review by the Science Advisory Board (SAB) as well as an extended public comment period. In October 2009, the Sarasota Bay Estuary Progra m (SBEP) Policy and Management boards directed the Technical Advisory Committee (TAC) to deve lop numeric nutrient criteria for the estuarine waters of the Sarasota Bay system. The primary objectives of this project were to:

 develop a data base of water quality and nutrien t loads for each of the major bay segments;

 define the chlorophyll a thresholds that meet light atte nuation and seagrass targets in each bay segment;

 define the quantitative relationships between nutrient concentrations or loading and chlorophyll a concentrations in each bay segment; and

 estimate the numeric nutrient criteria, i.e., the nut rient concentrations or loading consistent with the chlorophyll a thresholds, for each bay segment. This effort would fulfill the need for establishing NNC based on the best available data for the following SBEP estuarine segments:

 Palma Sola Bay

 Sarasota Bay

 Roberts Bay

 Little Sarasota Bay

 Blackburn Bay A water quality subcommittee of the TAC bega n the NNC development process by reviewing existing seagrass and chlorophyll a data and proposing a set of chlorophyll a targets to support the development of the NNC. This review confirmed th at the recent extents of seagrasses are meeting the established targets; the subcommittee thus determined that th e recent chlorophyll a concentrations and resultant water clarity must be protective of the seagrasses in each of the segments. Upon review of the chlorophyll a concentration data, it wa s deemed appropriate to include not only the data from th e 2004-2005 time frame but also data from several antecedent

# iii years (2001-2003). The resultant mean chlorophyll a concentrations from this overall period (2001-2005) were established as the targets for each segment. These targets are:

 Palma Sola Bay – 8.5 μg/L

 Sarasota Bay – 5.2 μg/L

 Roberts Bay – 8.2 μg/L

 Little Sarasota Bay – 8.2 μg/L

 Blackburn Bay – 6.0 μg/L The subcommittee further recogniz ed that there may be years in which these targets may be exceeded without causing significant reductions in se agrass cover. This means that there is some allowable, or acceptable, amount of variation th at should not elicit a significant degradation in water quality and therefore seagrass coverage. The subcommittee defined this level of variation as “the standard deviation around the mean annual chlorophyll a concentrations in each segment for the entire period of record”. Therefore, 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 and should not be exceeded. The chlorophyll a threshold for each segment is “the sum of the ta rget and the standard deviation around the mean annual chlorophyll a concentrations for that segment”. Therefore, the sum of the mean chlorophyll a concentrations for 2001-2005 and the standard deviation around the mean annual chlorophyll a concentrations for that segment are the thresholds that were used in the development of the numeric nutrient criteria in the SBEP estuarine waters. They are:

 Palma Sola Bay – 11.8 μg/L

 Sarasota Bay – 6.1 μg/L

 Roberts Bay – 11.0 μg/L

 Little Sarasota Bay – 10.4 μg/L

 Blackburn Bay – 8.2 μg/L The water quality data used in these analyses we re provided by Sarasota and Manatee counties. These data included monthly chlorophyll a , TN, TP, salinity, color, turb idity, and other variables. The nutrient and hydrologic loading estimates were developed by applying the Spatially Integrated Model for Pollutant Loading Estimates (SIMPLE) which was designed and calibrated by Jones Edmunds & Associates, Inc. for Sarasota County. In addition to the water quality and nutrient loading data, estimates of residence times for ea ch segment were derived based on the physical features and hydrologic loads for each segment. A linear regression model approach was used to develop statistically defensible relationships between potential stressors and water quality res ponses. The independent variables used in the model building process included nutrient loadings , nutrient concentrations, and estimates of residence time. The loadings data included m onthly hydrologic, TN, and TP loads as well as cumulative total loads extending fr om two to six months (e.g., 2-month cumulative TN load = TN load current month + TN load one- month prior) . The water quality constituents included TN and TP concentrations along with numerous other constituents. The stressor-response relationships for Roberts Bay, Little Sarasota Bay, and Blackburn Bay indicated very similar responses in chlorophyll a concentrations to changes in nutrient concentrations. Specifically, two terms, TN concen tration and season, explained more than 60% of

# iv the variation in the chlorophyll a data. These results indicate that there are significant relationships between chlorophyll a and TN concentrations in each of these segments and that these relationships vary between the wet and dry seasons. The relationship between chlorophyll a and TN concentrations in Sarasota Bay is more co mplex. This relationship depends upon location within the segment (north vs. south) and the ambient water color. Based on the quantitative relationships between chlorophyll a and TN concentrations in each of these segments and the chlorophyll a thresholds, the NNC expressed as mean annual TN concentrations were determined for each segment. These criteria are:

 Roberts Bay – 0.54 mg/L,

 Little Sarasota Bay – 0.60 mg/L,

 Blackburn Bay – 0.43 mg/L, and

 Sarasota Bay – 0.28-1.34 mg/L (based on ambient water color for the period 1998-2009). No significant relationship was found between chloro phyll a concentrations and either nutrient (TN or TP) concentrations or loadings in Palma Sola Bay. Given this result, an alternative method for proposing NNC for Palma Sola Bay was necessary. The SBEP water quality subcommittee of the TAC c onsidered three potential candidate methods for estimating the TN criterion for Palma Sola Bay. These methods included a logistic regression approach, a changepoint analysis approach, and an approach similar to that used to define the chlorophyll a thresholds. All three potential candida te methods give relatively similar results . The subcommittee recommended the third option – i.e., that based on the 2001-2005 ambient TN data. The proposed NNC for Palma Sola Bay is:

 a mean annual TN concentration of 0.93 mg/L. The full TAC concurred with the subcommittee’s recommendation on 23 July 2010.

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# I. Introduction The Sarasota Bay Estuary Program (SBEP) began in June 1989 when Sarasota Bay was designated an "estuary of national significance" by the U.S. Congress as part of the Water Quality Act of 1987. SBEP is one of 28 National Estuary Programs ( www.epa.gov/nep/ ) in the United States. The Sarasota Bay Estuary Program is a member of the Association of National Estuary Programs ( www.nationalestuaries.org/ ). The SBEP partners include:

 Sarasota County,

 Manatee County,

 City of Sarasota,

 City of Bradenton,

 Town of Longboat Key,

 Florida Department of Environmental Protection,

 Southwest Florida Water Management District, and

 U.S. Environmental Protection Agency.
SBEP was initially tasked with characterizing th e environmental conditions of Sarasota Bay and formulating a comprehensive restoration and pr otection plan based upon this analysis. The resulting plan was the Comprehensive Conservation and Management Plan (CCMP). The CCMP recommends specific actions to be taken by local governments as well as state and federal agencies to restore and protect Sarasota Bay. The CCMP was formally approved by the Governor of Florida and the Administrator of the U.S. Environmental Protection Agency in 1995. SBEP has been a focal point for the local governmen t agencies and assists them in their efforts to protect water quality in the estuarine waters of the area. To this end, SBEP has provided a forum for the establishment of critical environmental endp oints to assure increasingly difficult funding opportunities are being effectively applied. 

# II. Objectives The primary objectives of this project are:

 To develop a data base of water quality and nutrient loads for each of the major bay segments;

 To define the chlorophyll a thresholds that meet light attenuation and seagrass targets in each bay segment;

 To define the quantitative relationships betwee n nutrient concentrations or loading and chlorophyll a concentrations in each bay segment; and



#  To estimate the numeric nutrient criteria, i.e., the nutrient concentrations or loading consistent with the chlorophyll a thresholds, for each bay segment.

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# III. SBEP Goals and Targets Sarasota Bay is a coastal lagoonal system formed by a necklace of barrier islands to the west and the mainland of Manatee and Sarasota Counties to the east (Figure III-1). This coastal lagoon, with its unique ecological character of small embayments, tidal tributaries and small creeks, coves, inlets and passes, is bounded by Anna Maria Sound to the north and stretches all the way to just north of the Venice Inlet, which serves as its southern boundary. The overall watershed is approximately 455 square miles. The bay itself is approximatel y 56 miles long and has an average depth of 6.5 feet. Sarasota Bay is made of a series of smaller bays or segments. Each of these segments are unique from one another. They differ in overall size, sh ape and water depth, shoreline features, habitat and sediment characteristics. These unique characte ristics lead to differences in water circulation, freshwater inputs, nutrient loads, as well as other consequences for health and vitality. Because of these differences, each embayment must be anal yzed and managed independently from the others at the same time recognizing their connectivity. The Sarasota Bay Estuary Program recognizes the following segments as having their own unique set of conditions and influences: Palma Sola Bay, Sarasota Bay proper, Roberts Bay, Little Sarasota Bay, and Blackburn Bay.

Figure III-1. - Sarasota Bay Estuary Pr ogram segments and their watersheds.

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# Sarasota Bay was named an estuary of “national si gnificance” in 1987 which led to its designation as a National Estuary Program by the EPA two year s later. The Sarasota Bay Estuary Program is dedicated to improving and protecting the area’s greatest and most important natural asset - Sarasota Bay. The SBEP strives to improve wate r quality, increase habitat and enhance the natural resources of the area for use and enjoyment by the public. A Management Conference was formed comprising federal, state, regional and local officials who oversaw the development and implementation of a Comprehensive Conservation and Management Plan (CCMP) for Sarasota Bay. The Policy Comm ittee established the goals, objectives, budgets and work plans for the conference. Several priority concerns were identified:

 Declines in water and sediment quality

 Loss of wetlands and other coastal habitats

 Loss of seagrasses

 Declines in finfish and shellfish populations

 Overuse The Management Conference also developed plans of action to address these concerns through technical studies and citizen action plans which resulte d in the development of the CCMP in 1995. Progress in the implementation of the CCMP has b een documented. A State of the Bay report (SBEP, 2010) has been recently completed and a summary of these accomplishments is given in Appendix 1. In addition to other goals, the SBEP has estab lished quantitative targets for the restoration and protection of seagrasses (Janicki et al., 2009) and for water quality, specifically chlorophyll a concentrations (Janicki Environmental, 2010a). 

# III-1. Seagrass Targets One of the primary SBEP goals is to maintain and/ or restore seagrass coverage to its historic extent. The seagrass target project provided technical ly-defensible quantitative seagrass targets for the Sarasota Bay ecosystem. Establishment of se agrass targets provides a necessary basis for management decisions regarding water quality and ot her issues that can influence the distribution and persistence of this resource. Targets were de fined through an analysis of historic and recent aerial surveys of the study area. The historic aerial photos used to establish the ba seline extent of seagrass in the study area were dated circa 1950. Recent trends in and pers istence of seagrass throughout the SBEP were determined through analysis of GIS shapefiles ba sed on aerial surveys executed biannually by the Southwest Florida Water Management District since 1988. Due to anthropogenic modifications in the estuary such as shoreline build-out and the dr edging of the Intracoastal Waterway (ICW), certain areas have been altered to the extent that they have no reasonable potential for restoration; these so-called non-restorable areas have been identified and removed from the analyses. The trend analyses show that Sarasota Bay proper is currently at its highest seagrass level since 1950 and exceeds the baseline exten t (Figures III-2 – III-65). The seagrass coverage in Roberts Bay

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# and Blackburn bays also increased since the baseline period. In Palma Sola Bay, the seagrass coverage has remained very similar over the entire pe riod of record. In contrast, Little Sarasota Bay has shown a decline in seagrasses since 1950. The definition of the most appropriate seagrass targets was reached with input from the Technical Advisory Committee (TAC). The TAC recommended that the greater of either the historic or recent (2004-2006) seagrass coverages be established as the target in each segment. The sole exception to this rule was Little Sarasota Bay. Since 1984, th e direct connection to the Gulf of Mexico (Midnight Pass) has been closed. This physical alteration ma y have contributed to the difference in seagrass coverage between the historic and current coverag es. However, a recent FDEP decision precludes re-opening of this pass. Therefore, the recent co verage in Little Sarasota Bay has been established as the target. Table III-1 presents the seagrass ta rgets that were adopted by the SBEP Management and Policy boards.

Figure III-2. Annual seagrass acreages in Palma Sola Bay. Horizontal line = seagrass target. 

# 0 200 400 600 800 1000 1200

1950 1988 1994 1999 2001 2004 2006

# 5 Figure III-3. Annual seagrass acreages in Sarasot a Bay. Horizontal line = seagrass target.

Figure III-4. Annual seagrass acreages in Robe rts Bay. Horizontal line = seagrass target. 

# 0 1000 2000 3000 4000 5000 6000 7000 8000

1950 1988 1994 1999 2001 2004 2006

0 50 100 150 200 250 300 350 400

1950 1988 1994 1999 2001 2004 2006

# 6 Figure III-5. Annual seagrass acreages in Little Sar asota Bay. Horizontal line = seagrass target.

Figure III-6. Annual seagrass acreages in Blackburn Bay. Horizontal line = seagrass target. 

# 0 100 200 300 400 500 600 700 800 900 1000

1950 1988 1994 1999 2001 2004 2006

0 50 100 150 200 250 300 350 400 450 500

1950 1988 1994 1999 2001 2004 2006

# 7 Table III-1. SBEP seagrass coverage and targets. Unit of
measure=acres.

Bay Segment Historical (1950) Current 2004-2006

Average Seagrass Target Palma Sola 1,031 1,015 1,031 Sarasota 7,269 7,041 7,269 Roberts 283 348 348 Little Sarasota 883 702 702 Blackburn 273 447 447 Total 9,739 9,552 9,997 

# III-2. Chlorophyll a Targets and Thresholds In October 2009, the SBEP Policy and Management boards directed the TAC to develop numeric nutrient criteria for the estuarine waters of the ar ea. A subcommittee of the TAC began the process by reviewing the existing seagrass and chlorophyll a data and proposing a set of chlorophyll a targets to support the development of the numeric nutrient criteria (Janicki Environmental, 2010). Given that the recent extents of seagrasses are meeting the established targets, the subcommittee determined that the recent chlorophyll a concentrations and resultant water clarity are protective of the seagrasses in each of the SBEP segm ents. Upon review of the chlorophyll a concentration data, it was deemed appropriate to include not only the data from the 2004-2005 period but also from several antecedent years (2001-20 03). The resultant mean chlorophyll a concentrations from this overall period (2001-2005) were established as th e targets for each segment (Table III-2). The subcommittee further recognized that there may be years in which these targets may be exceeded without causing significant reductions in seagrass cover. This means that there is some allowable amount of variation that should not elicit a sign ificant degradation in water quality and therefore seagrass coverage. The subcommittee defined this level of variation as the standard deviation around the mean annual chlorophyll a concentrations in each segment for the entire period of record. Therefore, 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 chlorophyll a threshold for each segment is the sum of the target and the standard deviation around the mean annual chlorophyll a concentrations in each segment. The thresholds shown in Table III-1 are us ed in later sections of this report in the development of the numeric nutrient crite ria in the SBEP estuarine waters.
Table III-2. Recommended chlorophyll a targets and thresholds ( μ g/L). Bay Segment Target Chlorophyll a ( μ g/L) Inter-annual Variability (1 SD of Annual Means) Threshold Chlorophyll a ( μ g/L) Palma Sola 8.5 3.3 11.8 Sarasota 5.2 0.9 6.1 Roberts 8.2 2.8 11.0 Little Sarasota 8.2 2.2 10.4 Blackburn 6.0 2.2 8.2

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# IV. Recent Water Quality Assessments
This section provides an examination of water quality data for total nitrogen (TN), total phosphorus (TP), chlorophyll a , and salinity within the SBEP estuarine ar ea to identify any spatial and temporal trends. Bay segments in the SBEP area include Pa lma Sola Bay, Sarasota Bay, Roberts Bay, Little Sarasota Bay, and Blackburn Bay (Figure IV-1). This summary will be used to assist in setting locally-appropriate numeric nutrient criteri a for estuaries in the SBEP system.

Figure IV-1. - Sarasota Bay Estuary Program segments and their watersheds.

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# IV-1.0 Ambient Water Quality Sampling Programs in the SBEP Area
Both Sarasota County and Manat ee County collect water quality data within the SBEP area. The two monitoring programs are briefly described below. Maps showing the sampling sites from both programs are presented in Appendix 2.
The Sarasota County ambient water quality monitori ng program was initiated in 1998. Sarasota Bay was divided into 12 segments, each with mult iple randomly chosen sampling sites. Samples are collected on a monthly basis from each segment. All sample locations are sampled once every year. Each sampling location is also re-sampled every year in the same month as the preceding years. This stratified random monitoring progra m characterizes overall estuarine health by describing entire bay segments rather than isolated locations in each water body.
The Manatee County Environmental Managemen t Department (EMD) ambient water quality monitoring program for Manatee County's estuarin e waters is the Regional Ambient Monitoring Program (RAMP). The Manatee County RAMP prog ram divides the County's estuarine area into two segments of 24,356 km 2 

# hexagonal sampling areas each. The south segment includes Palma Sola Bay and Sarasota Bay north of the county line, both of which are within the SBEP area.
Sampling points were randomly located within e ach hexagon at the start of the program. A hexagonal sampling area was included in the pr ogram if the randomly generated sampling point was at least 4ft deep by the nautical chart and verified during program reconnaissance. One-third of the sampling points in each segment, eight point s, are sampled monthly. All sampling points in a segment are visited within each calendar quarter. In bay segments where both Sarasota and Manatee counties collected data, these data were averaged.
Times series of monthly mean values for each bay segment were produced to allow visual inspection of trends over time and to allow a comparison between bay segments. Trends in chlorophyll a , TN, or TP concentrations were assesse d using graphical plots and the seasonal Kendall Tau trend test (Hirsch et al., 1982; Hirs ch and Slack, 1984; Reckhow, 1993). The seasonal Kendall Tau is a nonparametric test that estimates the median slope from all pair-wise comparisons in a timeseries of data. The statistical test acc ounts for seasonality and serial autocorrelation prior to evaluating the statistical significance of the trend in the time series. Therefore, the seasonal Kendall Tau is a sophisticated and robust method to evaluate trends in water quality data that often do not fit the assumptions necessary for the use of parametric statistics (e.g. linear regression).

In addition to the examination of inter-annual vari ability, box and whisker plots were generated to examine within-year variability in water quality in each of the bay segments.
Besides tidal action, rainfall provides a driver fo r changes to surface water quality. Both direct rainfall on a water body and stormwater runoff from the watershed cause nonpoint source loadings to be a major factor in most receiving waters ’ quality. Annual rainfall for the 1998 though 2009

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# period is summarized in Table IV-1. The rainfall da ta are described in Chapter V below. It may be expected that years with high rainfall would cause changes to water quality, such as lower salinity, in segments with larger watersheds, while segmen ts with smaller watersheds that contribute runoff would show less of an effect.

Table IV-1. Annual rainfall in the SBEP area sorted by rainfall. Year Rainfall (inches) 2000 32.8 2007 34.2 2009 43.4 2008 44.2 2006 45.3 2001 46.9 1999 49.7 2004 51.9 2002 53.4 1998 57.3 2003 60.3 2005 61.2


# IV-2.0 Ambient Water Quality Assessment
The following summarizes annual and seasonal trends in salinity, TN, TP, and chlorophyll a for each SBEP bay segment. Results are based on a review of data for the period January 1998 through December 2009, except Palma Sola Bay that had data available only through December 2008.
IV-2.1 Palma Sola Bay
IV-2.1.1 Salinity
Mean annual salinity for the 1998 through 2008 period in Palma Sola Bay averaged 29.8 parts per thousand (ppt) (Figure IV-2). The lowest annual value, 22.3 ppt occurred in 2008 and the highest annual value, 34.8 ppt, occurred in 2000, a very dry year (Table IV-1). There was no significant trend in salinity in Palma Sola Bay over this time period (p>0.05; Appendix 2).
The box-and-whisker plots for salinity show values lower in the summer wet season than in the dry season, as would be expected (Figure IV-3). Monthly means range from 32.1ppt (May) to 25.0 ppt (October).

# 11 Figure IV-2. Mean monthly salinity (ppt) observed in Palma Sola Bay. The line is a least squares fit to the data.

Figure IV-3. Box-and-whisker plots of the mean monthly salinity (ppt) obser ved in Palma Sola Bay.


# IV-2.1.2 Chlorophyll a Mean annual chlorophyll a concentrations for the 1998-2008 period in Palma Sola Bay averaged 8.25 μg/L (Figure IV-4). The lowest annual value of 4.89 μg/L occurred in 2005, a significantly wet year (Table IV-1). Lower chlo rophyll concentrations may be expected if higher volumes of freshwater are reducing residence time on an annua l basis. The highest annual value, 11.3 μg/L, occurred in 1998, also a wet year. A si gnificant decreasing trend in chlorophyll a concentrations was observed during the 1998-2008 period (p<0.0001, Appendix 3).

# 12 Figure IV-4. Mean monthly chlorophyll a concentrations (μg/L) obs erved in Palma Sola Bay.



# Chlorophyll a monthly box-and-whisker plots show a defin ite seasonal signal (Figure IV-5). During the warmer summer months when nutrient loading is typically greatest and day length increases, the mean monthly chlorophyll a concentrations are much higher than those observed in the dry, cooler period of the year. Monthly means range from 12.4 μg/L (July) to 5.26 μg/L (November).

Figure IV-5. Box-and-whisker plots of the mean monthly chlorophyll a concentrations (μg/L) observed in Palma Sola Bay.

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# IV-2.1.3 Total Nitrogen
The mean annual TN concentrations for the 1998-2008 period in Palma Sola Bay averaged 0.77 mg/L (Figure IV-6). The lowest annual concentr ation (0.59 mg/L) occurred in 2004; the highest annual value of 1.09 mg/L occurred in the drought year of 2001. There was no significant trend in TN concentrations in Palma Sola Bay over this time period (p>0.05; Appendix 3).
The box-and-whisker plot for TN suggests some intr a-annual trend in TN concentrations (Figure IV7). Values are somewhat higher in the late summer months. Monthly means range from 1.03 mg/L (September) to 0.59 mg/L (April). Higher monthl y values during the summer are likely the result of increased TN loading during the wetter summer months.

Figure IV-6. Mean monthly TN concentrat ions (mg/L) observed in Palma Sola Bay.

Figure IV-7. Box-and-whisker plots of the mean monthly TN concentrati ons (mg/L) observed in Palma Sola Bay.

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# IV-2.1.4 Total Phosphorus
Mean annual TP for the 1998-2008 period in Palma Sola Bay averaged 0.16 mg/L. The lowest annual value (0.07 mg/L) occurred in 2004, a modera tely wet year (Table IV-1). The highest annual value (0.33 mg/L) occurred in 20 08. A statistically significant, but slight increasing trend in TP concentrations was observed during the 1998-2008 period (p<0.0001, Appendix 3).

Figure IV-8. Mean monthly TP concentrat ions (mg/L) observed in Palma Sola Bay.


# Unlike TN, there was very little within-year variability in TP concentrations (Figure IV-9). Monthly means for March, April, and May are as high as summer month values. Mo nthly means range from 0.22 mg/L (May) to 0.10 mg/L (November).

Figure IV-9. Box-and-whisker plots of the mean monthly TP concentrati ons (mg/L) observed in Palma Sola Bay.

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# IV-2.2 

# Sarasota Bay
IV-2.2.1 Salinity
Mean annual salinity for the 1998 through 2009 pe riod in Sarasota Bay averaged 34.5 ppt (Figure IV-10). The lowest annual value, 31.9 ppt, occurr ed in 1998, a wet year as shown in Table IV-1. The highest mean annual salinity, 36.3 ppt, occurre d in 2008, a dry year. There was a significant increasing trend in salinity in Sarasota Bay over this time period (p<0.01; Appendix 3).

Figure IV-10. Mean monthly salin ity (ppt) observed in Sarasota Bay.


# The salinity box-and-whisker plots show values so mewhat lower in the su mmer wet season than in the dry season, as would be expected, but the w ithin-year variation is not great with monthly means varying less than 3 ppt. Monthly means ra nge from 35.3 ppt (June) to 32.8 ppt (January).

Figure IV-11. Box-and-whisker plots of the mean monthly salinity (ppt) observed in Sarasota Bay.

# 16 

# IV-2.2.2 Chlorophyll a Mean annual chlorophyll a for the 1998 through 2009 period in Sarasota Bay averaged 5.0 μg/L (Figure IV-12). The lowest annual value of 3.3 μg /L occurred in 2006, a year of moderate rainfall (Table IV-1). The highest annual value, 6.0 μg/L, occurred in 2009, a dry year. There was a statistically significant but slight decreasing tren d in chlorophyll a concentrations in Sarasota Bay during this period (p<0.03, Appendix 3).

Figure IV-12. Mean monthly chlorophyll a concentrations (μg/L) observed in Sarasota Bay.


# Box-and-whisker plots of the mean monthly chlorophyll a concentrations show a definite seasonal signal (Figure IV-13). During the warmer summer months the mean monthly chlorophyll a concentrations were approximately 3X higher th an those observed in the dry period. Monthly means range from 9.3 μg/L (Septe mber) to 2.8 μg/L (February)."

Figure IV-13. Box-and-whisker plots of the mean monthly chlorophyll a concentrations (μg/L) observed in Sarasota Bay.

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# IV-2.2.3 Total Nitrogen
The mean annual TN concentrations for the 1998 through 2009 period in Sarasota Bay averaged 0.35 mg/L (Figure IV-14). The lowest annual valu e of 0.28 mg/L occurred in 2006, a moderately dry year (Table IV-1). The highest mean annual c oncentration of 0.41 mg/L occurred in 2004, a somewhat wetter year. There was no statistically si gnificant trend in TN concentrations in Sarasota Bay during this period (p>0.05, Appendix 3).
The box-and-whisker plot for mean monthly TN conc entrations suggests some within-year variation with somewhat higher concentrations in the la te summer months (Figure IV-15). Monthly means range from 0.49 mg/L (September) to 0.29 mg/L (February).

Figure IV-14. Mean monthly TN concentr ations (mg/L) observed in Sarasota Bay.

Figure IV-15. Box-and-whisker plots of the mean monthly TN concentrations (mg/L) observed in Sarasota Bay.

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# IV-2.2.4 Total Phosphorus

Mean annual TP concentrations for the 1998-2009 period in Sarasota Bay averaged 0.13 mg/L (Figure IV-16). The lowest mean annual concentr ation of 0.06 mg/L occurred in 2009, while the highest annual value, 0.22 mg/L, occurred in 2002 . There was a statistically significant but slight decreasing trend in Sarasota Bay TP concentra tions during this period (p<0.03, Appendix 3).

Figure IV-16. Mean monthly TP concentr ations (mg/L) observed in Sarasota Bay.


# The box-and-whisker plot of mean monthly TP conc entrations shows higher concentrations more likely during the summer months (Figure IV-17). Monthly means range from 0.18 mg/L (July) to 0.09 mg/L (November), a two-fold difference.

Figure IV-17. Box-and-whisker plots of the mean monthly TP concentrati ons (mg/L) observed in Sarasota Bay.

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# IV-2.3 Roberts 

# Bay
IV-2.3.1 Salinity
Mean annual salinity for the 1998-2009 period in Roberts Bay averaged 31.3 pp (Figure IV-18). The lowest annual value, 28.6 ppt, occurred in 2003, a wet year (Table IV-1). The highest annual value, 33.6 ppt, occurred in the 20 00 drought year. There was no statistically significant trend in salinity in Roberts Bay during this period (p>0.05, Appendix 2).

Figure IV-18. Mean monthly salinity (ppt) observed in Roberts Bay.


# The salinity box-and-whisker plots for salinity show the most distinct seasonal pattern among the SBEP segments, with summer wet season salinities mu ch lower than in the dry season as would be expected (Figure IV-19). Roberts Bay exhibits this wide within-year variation due to the significant freshwater inputs delivered by Phillippi Creek. M onthly means range from 34.9 ppt to 27.2 ppt.

Figure IV-19. Box-and-whisker plots of the mean monthly salinity (ppt) observed in Roberts Bay.

# 20 

# IV-2.3.2 Chlorophyll a Mean annual chlorophyll a concentrations for the 1998-2009 period in Roberts Bay averaged 7.3 μg/L (Figure IV-20). The lowest mean annual concentration of 3.6 μg/L occurred in 2007, a dry year (Table IV-1). The highest mean annual concen tration, 11.6 μg/L, occurred in the drought year of 2001. There was no statistically significant trend in chlorophyll a concentrations in Roberts Bay during this period (p>0.05, Appendix 3).
The box-and-whisker plot of mean monthly chlorophyll a concentrations shows significant withinyear variation (Figure IV-21), with values during the hotter summer months over five times as high as the cooler period of the year. Monthly me ans range from 16.8 μg/L to 2.97 μg/L.

Figure IV-20. Mean monthly chlorophyll a concentrations (μg/L) observed in Roberts Bay.

Figure IV-21. Box-and-whisker plots of the mean monthly chlorophyll a concentrations (μg/L) observed in Roberts Bay.

# 21 

# IV-2.3.3 Total Nitrogen
The mean annual TN concentrations for the 1998 through 2009 period in Roberts Bay North averaged 0.43 mg/L (Figure IV-22). There was very little inter-annual variation in TN concentrations. The lowest annual value of 0.36 mg/L occurred in 2007 with the highest mean annual TN concentration of 0.48 mg/L observed in 2002. There was no statistically significant trend in TN concentrations in Roberts Bay during this period (p>0.05, Appendix 3).

Figure IV-22. Mean monthly TN concentr ations (mg/L) observed in Roberts Bay.


# The box-and-whisker plot for TN presents a distinct seasonal trend in TN concentrations (Figure IV23). The highest TN concentrations were observe d in the late summer months (July, August, and September) and lowest during the winter mont hs. Monthly means range from 0.59 mg/L (September) to 0.34 mg/L (April).

Figure IV-23. Box-and-whisker plots of th e mean monthly TN concentrations (mg/L) observed in Roberts Bay.

# 22 

# IV-2.3.4 Total Phosphorus

Mean annual TP concentrations for the 1998 thr ough 2009 period in Roberts Bay averaged 0.17 mg/L (Figure IV-24). The lowest mean annual TP concentration (0.09 mg/L) occurred in 2009 and the highest annual mean annual (0.22 mg/L) wa s observed in 2001. There was a significant decreasing trend in Roberts Bay TP concentrati ons during this period (p<0.0001, Appendix 3).

Figure IV-24. Mean monthly TP concentr ations (mg/L) observed in Roberts Bay.


# There was an appreciable within-year variation in Roberts Bay TP concentrations (Figure IV-25). Mean monthly TN concentrations ranged from 0.21 mg/L (August) to 0.14 mg/L (January).

Figure IV-25. Box-and-whisker plots of the mean monthly TP concentrati ons (mg/L) observed in Roberts Bay.

# 23 

# IV-2.4 Little Sarasota Bay
IV-2.4.1 Salinity
Mean annual salinity for the 1998-2009 period in Little Saraso ta Bay averaged 30.8 ppt (Figure IV26). The lowest annual value, 27.3 ppt, occurred in 2005, a wet year (Table IV-1). The highest mean annual salinity, 33.6 ppt, was ob served 2007. There was no st atistically significant trend in salinity in Little Sarasota Bay during this period (p>0.05, Appendix 3).

Figure IV-26. Mean monthly salinity (ppt) observed in Little Sarasota Bay.


# The box-and-whisker plots for the mean monthly salinity in Little Sarasota Bay show a clear seasonal pattern, with summer wet season salinities much lower than those observed in the dry season (Figure IV-27). Monthly mean salinity ran ged from 34.6 ppt (June) to 25.8 ppt (September).

Figure IV-27. Box-and-whisker plots of the mean monthly salinity (ppt) observed in Little Sarasota Bay.

# 24 

# IV-2.4.2 Chlorophyll a Mean annual chlorophyll a concentrations averaged 7.3 μg/L in Little Sarasota Bay during the 1998- 2009 period (Figure IV-28). The lowest mean annual chlorophyll a concentration of 4.9 μg/L occurred in 2007 and the highest mean annual chlorophyll a concentration, 11.2 μg/L, occurred in 2007. There was a statistically significant but slight decreasing tr end in chlorophyll a concentrations in Little Sarasota Bay dur ing this period (p<0.05, Appendix 3).

Figure IV-28. Mean monthly chlorophyll a concentrations (μg/L) obser ved in Little Sarasota Bay.


# The mean monthly chlorophyll a concentrations exhibited a distinct seasonal signal (Figure IV-29). Monthly means ranged from 15.3 μg/L (September) to 3.4 μg/L (January).

Figure IV-29. Box-and-whisker plots of the mean monthly chlorophyll a concentrations (μg/L) observed in Little Sarasota Bay.

# 25 

# IV-2.4.3 Total Nitrogen

The mean annual TN concentrations in Little Sarasota Bay for the 1998 through 2009 period averaged 0.49 mg/L (Figure IV-30). The lowest mean annual TN concentration of 0.43 mg/L was observed in 1998 while the highest mean annual TN concentration was 0.56 mg/L found in 2001. There was no statistically significant trend in Little Sarasota Bay TN concentrations during this period (p>0.05, Appendix 3).

Figure IV-30. Mean monthly TN concentrat ions (mg/L) observed in Little Sarasota Bay.


# The TN concentrations in Little Sarasota Bay were higher in the late summer months (Figure IV-31). Monthly mean TN concentrations ranged from 0. 64 mg/L (September) to 0.39 mg/L (January).

Figure IV-31. Box-and-whisker plots of the mean monthly TN concentrations (mg/L) observed in Little Sarasota Bay.

# 26 

# IV-2.4.4 Total Phosphorus

Mean annual TP concentrations in Little Sarasota Bay averaged 0.17 mg/L during the 1998-2009 period (Figure IV-32). The lowest mean annual TP concentration was 0.09 mg /L in 2009; while the highest mean annual concentration was 0.22 mg/L in 1999. There was a statistically significant decreasing trend in Little Sarasota Bay TP concentr ations during this period (p<0.02, Appendix 3).

Figure IV-32. Mean monthly TP concentrat ions (mg/L) observed in Little Sarasota Bay.


# There was little within-year variation in TP concentr ations in Little Sarasota Bay during this period (Figure IV-33).

Figure IV-33. Box-and-whisker plots of the mean monthly TP concentrati ons (mg/L) observed in Little Sarasota Bay.

# 27 

# IV-2.5 Blackburn Bay
IV-2.5.1 Salinity
Mean annual salinity in Blackburn Bay in the 19 98-2009 period averaged 33. 5 ppt (Figure IV-34). The lowest mean annual salinity was 30.3 ppt whic h occurred in 2005, a relatively wet year (Table IV-1). The highest annual mean salinity was 35.7 ppt and occurred in 2000. There was no statistically significant trend in Blackburn Bay sa linity during this period (p>0.05, Appendix 3).

Figure IV-34. Mean monthly salinity (ppt) observed in Blackburn Bay.

Figure IV-35. Box-and-whisker plots of the mean monthly salinity (ppt) observed in Blackburn Bay.

# 28 

# IV-2.5.2 Chlorophyll a Mean annual chlorophyll a concentrations for the 1998-2009 pe riod in Blackburn Bay averaged 5.3 μg/L (Figure IV-36). The lowest annual mean chlorophyll a concentration was 3.0 μg/L and occurred in 2007. The highest annual mean chlorophyll a concentration was 9.3 μg/L and was observed in 2001. There was a significant decreasi ng trend in chlorophyll a concentrations in Blackburn Bay during this period (p<0.0001, Appendix 3).

Figure IV-36. Mean monthly chlorophyll a concentrations (μg/L) observed in Blackburn Bay. 

# The mean monthly chlorophyll a concentrations show a definite seasonal signal, with the highest concentrations observed during the summer months (Figure IV-37). Monthly mean concentrations ranged from 11.9 μg/L (September) to 1.9 μg/L (January).

Figure IV-37. Box-and-whisker plots of the mean monthly chlorophyll a concentrations (μg/L) observed in Blackburn Bay.

# 29 

# IV-2.5.3 Total Nitrogen
The mean annual TN concentrations during the 1998-2009 period in averaged 0.34 mg/L (Figure IV-38). The lowest annual mean TN concentrati on of 0.26 mg/L occurred in 1998. The highest annual mean concentration of 0.41 mg/L was observed in 2005. There was a statistically significant increasing trend in TN concentrations in Black burn Bay during this period (p<0.05, Appendix 3).

Figure IV-38. Mean monthly TN concentr ations (mg/L) observed in Blackburn Bay.


# The box-and-whisker plot for mean monthly TN c oncentrations show a distinct pattern with the highest TN concentrations observed from July th rough October (Figure IV-39). The monthly mean TN concentrations ranged from 0.49 mg /L (September) to 0.23 mg/L (May).

Figure IV-39. Box-and-whisker plots of the mean monthly TN concentrations (mg/L) observed in Blackburn Bay.

# 30 

# IV-2.5.4 Total Phosphorus
The annual mean TP concentrations in Blackburn Bay averaged 0.15 mg/L during the 1998-2009 period (Figure IV-40). The lowest annual mean of 0.06 mg/L occurred in 2009. The highest annual mean TP concentration was 0.21 mg/L and was obs erved in 2001. There was no statistically significant trend in Blackburn Bay TP concentratio ns during this period (p>0.05, Appendix 3).

Figure IV-40. Mean monthly TP concentr ations (mg/L) observed in Blackburn Bay.


# There was a slight seasonal trend in TP concentrati ons with slightly higher concentrations observed during the summer months (Figure IV-41). Monthly mean TP concentrations ranged from 0.17 mg/L (October) to 0.12 mg/L (November).

Figure IV-41. Box-and-whisker plots of the mean monthly TP concentrati ons (mg/L) observed in Blackburn Bay.

# 31 

# IV-3 Summary
The five SBEP bay segments exhibit a range of water quality characteristics based on watershed size, tributaries, estuary shape and size, and flush ing rate and circulation. Because of the limited size and similar land use of most of the watershe ds, flushing and tidal exchange appears to be a critical factor in water quality in the bay segments.
Sarasota Bay and Blackburn Bay have the best tidal exchange with the Gulf of Mexico. These two segments have the highest average annual sali nity and lowest average annual TN, TP, and chlorophyll a concentrations of the SBEP segments.
Palma Sola Bay and Little Sarasota Bay have the mo st restricted tidal exchange, and have the lowest salinity and highest TN, TP, and chlorophyll a concentrations of the segments. Roberts Bay receives significant nonpoint source loading from Phillippi Creek but has tidal exchange with the Gulf of Mexico via Big Sarasota Pass.
Temporal trends in the four parameters varied sign ificantly. Salinity showed an increasing trend in all segments except Palma Sola which had a slight downward trend. Trends in TN varied from slightly increasing (Palma Sola Bay) to strongly decreasing (Sarasota Bay). TP trends were strongly decreasing except for Palma Sola Bay which had a s lightly increasing trend, and Sarasota Bay which had a very slight decreasing trend. Chloroph yll a trends decreased in all five segments.
Seasonality also varied by parameter. Salinity seasonal variation was largest in Roberts and Little Sarasota Bays, moderate in Sarasota and Blackbu rn Bays, and lowest in Palma Sola Bay. TN showed a strong to moderate seasonal variation in all segments. TP seasonality was evident but much more muted that TN. Chlorophyll a seasonality was the most distinct, with large differences in wet/summer and dry/winter concentrations in all segments. Palma Sola Bay showed the least difference.

# 32 

# V. Characterization of Nutrient Loadings to the Sarasota Bay Estuary Segments This section provides a brief summary of the m odel used to develop hydrologic and nutrient loading estimates for each segment within the SBEP area and a discu ssion of the temporal trends in these loadings.


# V-1. Nutrient Loading Esti mates for Sarasota Bay Nutrient and hydrologic loads were estimated for the period 1988-2008 for five bay segments within the greater Sarasota Bay watershed (from nor th to south): Palma Sola Bay, Sarasota Bay, Roberts Bay, Little Sarasota Bay and Blackburn Ba y (Figure III-1). Drainage basins for each bay segment were delineated based on drainage boun daries provided by Manatee and Sarasota counties and are the same basins used to develo p loading estimates for Roberts Bay for the time period 1994-2008 (2009 RBay WMP). Nutrient loading estimates were derived for each of the 114 drainage basins using the Spatially Integrated Mode l for Pollutant Loading Estimates (SIMPLE) which was designed and calibrated by Jones Edmunds & Associates, Inc (JEA 2009 SIMPLE design report).
The SIMPLE model consists of six modules that produce pollutant loading estimates for the primary point and non-point sources within a watershed: 1) Direct Runoff, 2) Baseflo w, 3) Irrigation, 4) Point Source, 5) Septic Tanks, and 6) Atmosphe ric Deposition. We used the SIMPLE model to estimate nutrient loads for the first five sources, but calculated atmospheric deposition externally (see below for more detail). Nutrient loads from the SIMPLE model were combined with loads from atmospheric deposition to estimate Total Nutrient Loads to each bay segment. Rainwater runoff and groundwater flow, both tigh tly coupled to precipitation, are the primary mechanisms by which nutrients are transported from the watershed to Sarasota Bay. In order to estimate nonpoint source nutrient loads related to these hydrologic processes, the Direct Runoff and Baseflow modules reference an externally genera ted table of monthly hydrologic values that estimate rainfall, runoff and baseflow for all combina tions of land use and soil type in the Sarasota Bay watershed. Below, we describe the external hy drologic engine that estimates these hydrologic values. Then, we briefly outline the modules that estimate nutrient loads from runoff and baseflow. Finally, we outline the modules that estimate non-poi nt source contributions from irrigation and point source contributions from wastewater treatment facilities and septic tanks. 

# V-1.1 Estimation of Hydrologic Values The hydrologic engine used to estimate rainfa ll, runoff and baseflow was provided by Jones Edmunds and Associates, Inc. (JEA) as a conti nuous simulation spreadsheet model and was recoded to run using the Statistical Analysis Software package (SAS version 9.2). Parameter estimates derived from the original spreadsheet model, which was run by JEA for Sarasota County (1994- 2008), were compared with estimates derived from the recoded SAS engine to ensure identical model outputs prior to estimating hydrologic pa rameters for the pre-NEXRAD time period and for the Manatee County portion of the Sarasota Bay watershed. Precipitation and evapotranspiration data were the in puts required to run the hydrologic engine. Monthly rainfall estimates were made using NEXRAD rainfall data for 1994-2008 and data from SWFWMD and National Weather Service rain gauges for the pre-NEXRAD period from 1989-1993. Rainfall for the pre-NEXRAD period was estimated for each 2km x 2km NEXRAD pixel using the inverse-distance squared method to interpolate ra infall between gauges. Losses of water to

# 33 

# evapotranspiration were modeled as a function of water table level, soil moisture, and land use with potential evapotranspiration data prov ided by the U.S. Geological Survey. Runoff and baseflow were estimated on a daily ti me-step for each combination of NEXRAD pixel, land use and soil type and were then summed to obtain monthly values. Runoff estimates were based on those of the Natural Resource Conser vation Service (NRCS, 1986) and accounted for antecedent moisture conditions as well as diff erences in runoff volume from pervious and impervious surfaces, and as a result of changes in soil saturation as a function of rainfall. Baseflow was calculated using the Dupuit-Forcheimer equati on which is a function of the horizontal and vertical distances travelled by groundwater a nd hydraulic conductivity for each soil type. Estimates of monthly rainfall, runoff and groundwater were produced by the hydrologic engine and exported to a geodatabase table that was refere nced by the Direct Runoff and Baseflow modules during execution of the SIMPLE model.
V-1.2 Direct Runoff Monthly nutrient loads (lbs/month) and hydrologic loads (ft 3 

# /month) from runoff were estimated for each drainage basin. Runoff volumes and nutrien t concentrations were a function of the relative proportions of each land use and hydrologic soil type within each basin and were adjusted for land use changes over time using a time-stamped land use coverage for Sarasota county provided by JEA. The time-stamped land use coverage for Manatee county was created following the same procedure used to create the Sarasota coverage. Briefly, each land use polygon was time-stamped by intersecting historic (1990) and current (20 04 for Sarasota county, 2007 for Manatee county) land use coverages obtained from the Southwes t Florida Water Management District and then intersecting the resulting coverage with the parcel database retrieved from Manatee and Sarasota county Property Appraisers to create a land use co verage that described historic and current land uses and the year in which land uses changed over time. The soil coverage was retrieved from the USDA’s Natural Resources Conservation Service. The spatial coverage for lands treated by best management practices (BMPs) was created for Manatee County by subsetting from the land use coverage all polygons classified as reservoirs, go lf courses, open lands, and medium/high-density residential lands and lands permitted by SWFWMD ’s Environmental Resource Permit. SWFWMD aerial photography from 2008 was used to identify and digitize any additional BMPs. All BMPs were considered to be wet detention for the purpose s of estimating pollutant removal efficiencies.
V-1.3 Baseflow As with runoff, nutrient loads (lbs/month) and hydrologic loads (ft 3 

# /month) from baseflow were estimated for each drainage basin as a function of land use and soil type within the basin. Event mean concentrations for baseflow were held constant across land uses and soil types and were derived from literature values and used previ ously in other southwest Florida estuaries. V-1.4 Irrigation The spatial coverage for irrigated lands in Manate e County consisted of residential, commercial and agricultural lands, and golf courses. The source of irrigated water was assumed to be groundwater unless otherwise indicated by the coverage of areas with access to reuse water as provided by the Counties. Irrigation rate was assigned for lands in both Sarasota and Manatee Counties using a relationship between average parcel age and ma rket value and was calibrated through field observations of lawn health by Jones-Edmunds. Healthier lawns on golf courses and residential

# 34 

# lands were assumed to receive a higher rate of irrigation than less healthy lawns. Medium irrigation rates were assumed for agricultural lands. Nutrient loads from irrigation were corrected for irrigation of impervious areas and infiltration to groundwater so as not to overestimate irrigation loadings.
V-1.5 Point Sources Daily water quality data including nutrient concen trations and flows were obtained from Florida Department of Environmental Protection, Saraso ta County and Manatee County for the major point sources (> 0.1 MGD) for the model period, including 1989-1993 and 2008 to expand the existing water quality dataset for Sarasota County provided by Jones-Edmunds. Smaller non-delegated facilities treating <0.05 MGD were included in Sarasota County da taset but were not obtained for Manatee County. When data were not available for a given time period, monthly averages were calculated using existing data for that point sour ce. Improvements to the existing dataset were made by replacing previously averaged values with newly acquired data for the major point sources and by correcting total effluent volu mes for the City of Sarasota plant to account for surface water discharge as well as reuse. The only major point source in Manat ee County, the Southwest Wastewater Treatment Plant, was converted to adva nced wastewater treatment prior to 1989 with effluent being disposed via deep injection well and into the reuse system rather than being discharged directly to surface wate rs. Therefore, flows for this point source were considered to be 0 MGD. Non-compliant effluent (i.e., sewage spills, reuse spills) was accounted for in the point source module by referencing tables containing informati on on the location, volume and concentrations of non-compliant spills. Spill data were obtaine d from Manatee and Sarasota Counties. V-1.6 Septic Tanks The spatial coverage for septic tanks throughout th e bayshed was estimated by first assigning points representing septic tanks to each developed parcel and then by removing points from parcels that intersected the central sewer coverage provided by the Counties. A concentration of low, medium or high corresponding to literature values was th en assigned to each septic tank based on the hydrologic soil group, presence or absence of BMPs and distance from each tank to the nearest surface water as estimated using GIS. Failure rate was assigned as a percentage of tanks based on hydrologic soil group and tank age. V-1.7 Atmospheric Deposition Total atmospheric deposition is defined as the sum of wet depos ition (rainfall) and dry deposition (gaseous constituent interaction and dust fallout) dire ctly to the surface of the bay. Deposition of pollutants to the watershed of the bay is incor porated into nonpoint s ource loading estimates. Three types of data were used to estimate total atmospheric deposition:

 an estimate of the hydrologic load directly to the surface of the bay via precipitation;

 an estimate of the pollutant concentr ation in that precipitation; and

 an estimate of dry deposition, either from empirical data or model-based estimates.

# 35 

# Precipitation-derived hydrologic loads to the ba y surface were estimated as the total monthly rainfall using the rainfall dataset used to generate hydrologic loads to the watershed (described above). Mean monthly pollutant concentrations for total n itrogen (TN) in rainfall were obtained from the National Atmospheric Deposition Program (NADP) Vern a Wellfield site in Sarasota County. This site represents the nearest long-term site measur ing precipitation concentration data. TN loadings from precipitation were estimated by multiplyin g the monthly precipitation-weighted mean TN concentrations from the Verna site and the mo nthly bay surface hydrologic loads to estimate monthly wet TN loads to the bay. Estimates of wet deposition for nitrogen were calculated as follows :
Nwet m 

# =[N] m 

# * H m 

# , Nwet m 

# = wet deposition of nitrogen (kg/month) for each month m , [N] m 

# = mean precipitation-weighted nitrogen concentration (g/m 3 

# ) in the rainfall measured at the Verna Wellfield for each month m , and

H m 

# = estimated hydrologic load (m 3 

# /month) from rainfall for each month m to the bay surface. Concentrations for total phosphorus (TP) in rainfall were unavailabl e from the Verna site and had to be estimated from a relationship between rainfall concentrations of nitrogen and phosphorus which were based on data collected by the Tampa Bay Atmospheric Deposition Study (TBADS) were utilized (Poor, 2000). This program, running fr om 1996 to 2006, included sampling elements for both wet and dry deposition at an intensive monitoring site located on the Gandy Bridge Causeway. The data available from TBADS incl ude concentrations for nitrogen and phosphorus, wet and dry deposition rates, and an estimate of the ratio of dry:wet deposition, and have been used to estimate atmospheric deposition to Tampa Bay (Pribble et al., 2001). Estimates of dry deposition for both nitrogen and phosphorus were based on data collected at the TBADS site. Dry deposition was estimated usin g the TBADS-derived seasonal dry:wet deposition ratio, which was 1.05 for the dry season (months 1-6 and 11-12) and 0.66 for the wet season (months 7-10), as follows: Ndry m 

# = Seasonal Deposition Ratio * Nwet m 

# , Ndry m 

# = dry deposition of nitrogen (kg/month) for each month m , and

Nwet m 

# = wet deposition of nitrogen (kg/month) for each month m
. Total atmospheric deposition to a surface of the bay was given as the sum of the wet and dry deposition, as follows:

Ntot m 

# = Nwet m 

# + Ndry m 

# , Ntot m 

# = total atmospheric deposition of nitrogen (kg/month) for each month m to the surface of the bay.

# 36 

# V-2. Temporal Trends in Hydrologic and Nutrient Loadings by Bay Segment Hydrologic and nutrient loads were estimated fo r the period 1989-2008 for five bay segments within the SBEP area (from north to south): Palm a Sola Bay, Sarasota Bay, Roberts Bay, Little Sarasota Bay, and Blackburn Bay (Figure V-1).

Figure V-1. - Sarasota Bay Estuary Program segments and their watersheds.



# The total annual hydrologic, TN, and TP loads to each bay segment are presented in Figure V-2 through V-4 and are discussed in the following sections

# 37 Figure V-2. – Annual hydrologic loads by bay segment. BB=Blackburn Bay, LS=Little Sarasota Bay, PS=Palma Sola B ay, RB=Roberts Bay, SB=Sarasota Bay.

Figure V-3. – Annual TN loadings by bay segm ent. BB=Blackburn Bay, LS=Little Sarasota Bay, PS=Palma Sola Bay, RB=Roberts Bay, SB=Sarasota Bay



# .

# 38 Figure V-4. – Annual TP loadings by bay segmen t. BB=Blackburn Bay, LS=Little Sarasota Bay, PS=Palma Sola Bay, RB=Roberts Bay, SB=Sarasota Bay



# . Table V-1 presents the relative contribution to the recent (2008) loads to each bay segment. The contributions from direct runoff and base flow exceed 50% for each segment. Atmospheric deposition is relatively more important in Sarasota and Palma Sola bays, i.e., those segments with the greatest surface area.

Table V-1. Relative contribution (%) for each load type to the 2008 loads to each bay segment. Load Type BB LSB PSB RB SB Atmospheric Deposition 4.0 15.6 20.4 2.3 31.7 Base Flow 21.9 25.0 19.4 27.6 15.3 Direct Runoff 59.8 56.0 49.5 59.2 42.5 Irrigation 1.7 2.3 2.3 2.5 1.3 Septic 12.6 1.1 8.4 4.1 4.3 Point Source 0.0 0.0 0.0 4.3 4.8 

# V-2.1 Palma Sola Bay The highest annual hydrologic loads to Palma Sola Bay were observed during wetter years (generally >55 inches) of 1992, 1995, and 2003 (Figur e V-2). Drier years, in terms of total rainfall (<40 inches), occurred in 1990, 1999, 2000, and 2007 and corresponded to the lowest observed hydrologic loads during those years. As expected, the highest annual nutrient loadings for TN and TP were observed during years of peak hydrolog ic loads in 1988, 1992, 1995, 2003, and 2005 (Figures V-3 and V-4). Box-and-whisker plots of the hydr ologic and nutrient loadings for Palma Sola Bay are presented in Figures V-5-V-7. The bars represent the range of observations, while the upper and lower margins of the box indicate the 25th and 75 th 

# percentiles. The solid line is the median value and the dot is

# 39 

# the mean value. Mean hydrologic loads for Pa lma Sola Bay were highest during the wet season between June and October when average monthly loads ranged from 2.6 – 4.6 million cubic meters (Figure V-5). September had the highest a verage hydrologic loads in all bay segments, with October dropping sharply. During the dry se ason from November to May, average hydrologic loads to Palma Sola Bay ranged from 1.0 – 1. 8 million cubic meters pe r month. For all bay segments, May had the lowest hydrologic loads. Interestingly, March consistently had the highest hydrologic loads observed during the dry season. As a rule, the average monthly hydrologic load to each of the bay segments during the wet seas on was 2.5 times greater than that during the dry
season.

Figure V-5. – Average monthly hydrologic loads to Palma Sola Bay (1989-2008). 

# Average monthly loads for TN and TP were highest during the wet season (June-October) as expected from trends in rainfall and hydrologic lo adings, and peaked in September (Figures V-6 and V-7). TN loads to Palma Sola ranged from 8.00 2 to 10,089 lbs/month be tween June-September and declined to 2,494 to 43,982 lbs/month during th e dry season. TP loads displayed the same seasonal trends with the highest loads at 1,736 lb s in September at the end of the wet season and 485 lbs in May at the end of the dry season. As with hydrologic loads, wet- season nutrient loads were consistently greater than dry-season loads for TN (2.5 X greater) and TP (2 X greater).

Figure V-6. – Average monthly TN loads to Palma Sola Bay (1989-2008).

# 40 Figure V-7. – Average monthly TP loads to Palma Sola Bay (1989-2008). 

# V-2.2 Sarasota Bay As with Palma Sola Bay, higher-than-average a nnual hydrologic loads to Sarasota Bay were observed during wetter years of 1992, 1995, and 2003, as well as 2005 (Figure V-2). Drier years occurred in 1990, 1999, 2000, and 2007 and corresponded to the lowest observed hydrologic loads during those years. The highest annual nutrient loadings for TN and TP were observed during years of peak hydrologic loads in 1992, 1995, 2003, and 2005 (Figures V-3 and V-4). Sarasota Bay also had noticeably higher than average TN in 198 9 despite an average hydrologic load that year. Monthly hydrologic loads to Sarasota Bay were highest during the wet season between June and October when average loads ranged from 17.2 – 28.5 million cubic meters (Figure V-8). The highest hydrologic loads were observed in Septemb er. Average hydrologic loads were lowest to Sarasota Bay from November to May, with May cons istently having the lowest monthly loads. Dry season loads ranged from 7.8 – 11.8 million cubic me ters per month. Average monthly hydrologic loads during the wet season were 2.5 times gr eater than those during the dry season.

Figure V-8. – Average monthly hydrolog ic loads to Sarasota Bay (1989-2008). 

# Peak nutrient loads were observed between June-October with the highest monthly loads observed in September (Figures V-9 and V-10). Sarasota Bay received between 30,465 and 54,704 lbs TN/month between June-October but only one-thir d those amounts during the dry season, 14,180 to 25,437 lbs/month. Sarasota Bay also received higher TP loads during the wet season peaking at

# 41 

# 8,187 lbs/month, but only one-fourth the TP load during the dry season at 2,256 lbs/month in May. As with hydrologic loads, wet- season nutrient load s were consistently greater than dry-season loads for TN (2 times greater) and TP (2 times greater).

Figure V-9. – Average monthly TN loads to Sarasota Bay (1989-2008).

Figure V-10. – Average monthly TP loads to Sarasota Bay (1989-2008). 

# V-2.3 Roberts Bay The highest annual hydrologic loads to Roberts Bay were observed during wetter years of 1992, 1995, 2003, and 2005 (Figure V-2). Drier years occurred in 1990, 1999, 2000, and 2007 and corresponded to the lowest observed hydrologic loads during those years. The highest annual nutrient loadings for TN and TP were observed in 1992, 1995, 2003, and 2005 during years of peak hydrologic loads (Figures V-3 and V-4). High er than average annual nutrient loads were also observed during 1997 for Roberts Bay. Mean hydrologic loads for Roberts Bay were highest between June and October when average monthly loads ranged between 12.3 – 19.7 million cu bic meters (Figure V-11). September had the highest average hydrologic loads. The lowest hydrologic loads were observed between November and May when average loads to Roberts Bay ranged from 5.1 – 7.4 million cubic meters per month. As a rule, the average monthly hydrologic load to Roberts Bay during the wet season was 2.5 times greater than that during the dry season.

# 42 Figure V-11. – Average monthly hydrologic loads to Roberts Bay (1989-2008).



# TN and TP loads were also highest from June-Oct ober, peaking in September (Figures V-12 and V13). Roberts Bay received between 41,177 a nd 57,156 lbs TN/month between June-September while only one-third those amounts during the dry season, 15,622 to 21,585 lbs/month. Higher TP loads were observed for Roberts Bay during the wet season at 11,955 lbs/month compared to 4,620 lbs/month during the dry season. As with hydrologic loads, wet- season nutrient loads were consistently 3X greater than dry-season loads for TN and TP.

Figure V-12. – Average monthly TN loads to Roberts Bay (1989-2008).

# 43 Figure V-13. – Average monthly TP loads to Roberts Bay (1989-2008).



# V-2.4 Little Sarasota Bay Little Sarasota Bay received the highest annual hydrologic loads during 1992, 1995, 2003, and 2005 (Figure V-2). The highest TN and TP loads were observed during the same years (Figures V-3 and V-4). Lowest hydrologic loads occurred in 1990, 1999, 2000, and 2007. Mean hydrologic loads for Little Sarasota Bay were highest between J une and October when average monthly loads ranged from 3.0 – 5.0 milli on cubic meters (Figure V-14). The highest loads occurred in September and dropped off in Oct ober at the end of the wet season. Between November and May, average hydrologic loads to Little Sarasota Bays ranged from 1.3 – 1.9 million cubic meters per month, with May having the lo west hydrologic loads. The average monthly hydrologic load to Little Sarasota Bay was 2.5 tim es greater during the wet season than during the dry season.

Figure V-14. – Average monthly hydrologic loads to Little Sarasota Bay (1989-2008).

# 44 

# Average monthly loads for TN and TP (Figure V- 15 and V-16) were highest during the wet season (June-October) as expected from trends in rain fall and hydrologic loadings, and peaked in September and TN loads to Little Sarasota Bay ranged from 6,253 to 11, 380 lbs/month between June-September and dropped to 3,013 to 4,408 lbs/month during the dry season. Monthly TP averages during the wet season were between 1,2 60 and 1,948 lbs/month, but dropped to between 561 and 805 lbs/month during the dry season. Average wet- season nutrient loads were consistently greater than dry-season loads for TN (2.5 times greater) and TP (2 times greater).

Figure V-15. – Average monthly TN loads to Little Sarasota Bay (1989-2008).

Figure V-16. – Average monthly TP loads to Little Sarasota Bay (1989-2008).



# V-2.5 Blackburn Bay Blackburn Bay received the highest annual hydrol ogic loads during 1992, 1995, 2003, and 2005 (Figure V-2). As was the case throughout the greate r Sarasota Bay watershed, the lowest hydrologic loads to Blackburn Bay were observed in 1990, 1999, 2000, and 2007. The highest annual loadings for TN and TP were observed in 1992, 1995, 2003, and 2005 (Figures V-3 and V-4). Higher than average annual nutrient loads we re also observed during 1997 for Blackburn Bay. As was true for all bay segments within the Sara sota Bay watershed, Blackburn Bay experienced the highest monthly hydrologic loads during the wet season between June and October when loads

# 45 

# were between 3.1 – 5.1 million cubic meters (Fig ure V-17). Hydrologic loads were highest in September averaging 5.1 million cubic meters. The lowest monthly hydrologic loads were observed in May during the end of the dry season (November to May) when average hydrologic loads to Blackburn Bay ranged from 1.1 – 1.9 milli on cubic meters per month. Average hydrologic loads to Blackburn Bay during the wet season were 2.5 times greater than that during the dry
season.

Figure V-17. – Average monthly hydrologic loads to Blackburn Bay (1989-2008).



# The highest average monthly nutrient loads we re observed during the wet season from JuneOctober, with a peak loading in September, co rresponding to higher than average hydrologic loadings during those months (Figures V-18 and V-19). TN loads to Blackburn Bay ranged from 11,699 to 15,048 lbs/month between June-Septe mber and dropped to between 2,782 to 5,008 lbs/month during the dry season. TP loads were also highest in September at 2,406 lbs/month and lowest in May at 592 lbs/month. As with hy drologic loads, wet- season nutrient loads were consistently greater than dry-season loads for TN (2.5 times greater) and TP (2 times greater).

Figure V-18. – Average monthly TN loads to Blackburn Bay (1989-2008).

# 46 Figure V-19. – Average monthly TP loads to Blackburn Bay (1989-2008).



# V-3. Temporal Trends in Re sidence Times by Bay Segment A box model was developed to estimate the hydraulic residence times within the SBEP segments. The box model was based on observed salinity di stributions within the system and estimated freshwater inflows from the SIMPLE model to the sy stem. Methods were similar to those described by Hagy et al. (2000), with the exception that the SBEP system was assumed to be well mixed vertically, so that all transport was horizontal. Hydraulic residence time is also named the pulse residence time (PRT), as residence times are dependent upon introducing a pulse of tracer into a selected segment at the beginning of the box mo del simulation and tracking the time necessary for the concentration of this tracer to decrease to a certain level. The specific method used to estimate the pulse residence times for each segment is given in Appendix 4. The box model iterations resulted in segment- and monthly-specific estimates of PRT. For each segment, the median PRT for each year was calcu lated, and then the median PRT of the annual values for each segment were calculated. These segment-specific PRTs are provided in Table V-2, and represent the median hydraulic residence time within each segment given the observed conditions of 1994-2007.

Table V-2. Median annual pulse residence time for each segment based on 1994-2007 conditions. Segment Pulse Residence Time (days) Palma Sola Bay 35.8 Sarasota Bay 28.8 Roberts Bay 2.8 Little Sarasota Bay 19.2 Blackburn Bay 3.0



# A time series plot of the annual PRTs for each segment for the 1994-2007 period is provided in Figure V-20. As show in Table V-2, the PRTs are in units of days, so that a shorter PRT indicates more rapid exchange between the segment and the Gulf, and a longer PRT indicates slower

# 47 

# exchange. Not surprisingly, the smaller segments with large freshwater inflows relative to the segment size (Roberts Bay, Blackburn Bay) have mu ch shorter residence times (on the order of 10 times shorter) than do those with smaller inflows and relatively larger segment volumes (Sarasota Bay, Little Sarasota Bay). As can be seen from Figure V-20, the interannual variability in PRT is small for all segments, with only about 10% variab ility in PRT in those segments with longer residence times, and almost no variability in PRT in those segments with shorter residence times.

Figure V-20. Median annual PRTs (days) for each segment, based on monthly PRTs for each years.

# 48 

# VI. Relationships between Chlorophyll an d Nutrient Loads a nd Concentrations The objective of this section is to present the methods and results obtained in the development of quantifiable relationships between chlorophyll a and nutrient loadings and/or concentrations for each bay segment in the SBEP area. A summary of the potential empirical approaches to establish NNC was recently completed for the three Nati onal Estuary Programs on the Florida Gulf Coast (Janicki Environmental, 2010b). In most estuarine ecosystems N is the most limitin g nutrient (a nutrient whose concentration in the environment of an organism dete rmines the growth and productivity of that organism) (Boynton et., 1982; Howarth, 1988; Chapra, 1997; National Research Council, 2000; Pennock et al., 2000). Aquatic ecosystems are commonly characterized by their N:P ratios. Receiv ing waters with ratios less than 10:1 are considered nitrogen limited, while ratios higher than 10:1 are assumed to be phosphorus limited (FDEP, 2000). In Sarasota Bay, ratios between total nitrogen (TN) and total phosphorus (TP) are typically well below 10 (Lowr ey, 1992), which is consistent with presumed nitrogen limitation. In Roberts Bay, FDEP (2005) calculated a median TN:TP ratio of 2.4, indicating strong nitrogen limitation of phytoplankton growth. In addition, empirically derived relationships also point to the primary role of nitrogen in the eutrophication processes in Sarasota Bay (i.e., Tomasko et al. 1992 and 1996), as was found in the earliest studies in Tampa Bay (i.e., Johansson 1991). More recent assessments also support th e finding of nitrogen-limitation of macroalgae in Sarasota Bay (Dillon and Chanton, 2008).


# VI-1 Data Sources The water quality data used in these analyses are described in Section IV. The estimates of hydrologic, TN, and TP loadings used are described in Section V. Residence times used in these analyses are also described in Section V. 

# VI-2 Analytical Approach A linear regression approach was used to develop st atistically defensible relationships. Linear regression is a parametric statistical technique that is used to explore the relationship between two or more variables. In ordinary least-squares regression, the relationship between the dependent variable (y-axis) and independent variable (x-axi s) is developed. This is done by fitting a straight line through the set of points such that the sum of squared residuals of the model is as small as possible. That is to say, the vertical distance s between the individual points and the fitted line are minimized. In linear regression, it is assumed that the data ar e independent samples from the population that is being sampled. For example, the data should come from samples that are representative of the spatial and temporal variability of the system. An other important assumption of linear regression is that the error term of the model is normally distribu ted, with constant variance. Often times, one or more of the variables exhibits a non-linear relati onship with the other variables. While there are non-linear regression techniques that can be empl oyed, one should attempt to transform the data before resorting to nonlinear methods. Often, linear relationships can be developed using transformed data and these models will satisfy the assumptions of linear regression.

# 49 

# The stepwise regression procedure (SAS 9.2, 2010) was used to id entify the independent variables that have a significant relationship with chlorophyll a . In the stepwise procedure, the independent variables are added to the model one at a time and th e F statistic for the variable must be significant in order for the variable to be included in th e model. Unlike the forward procedure which only adds additional variables to the model, the step wise procedure examines the F statistic for all variables already included in the model after each step. Variables that are no longer significant based on the F statistic are removed. The resu lt is a ranked list of significantly contributing variables. Diagnostic statistics and plots are commonly used to determine if the regression model meets the assumptions of linear regression. The most commonl y used statistics are the statistical significance of the model parameters and the coefficient of determination (R 2 

# ). The statistical significance of the model parameters tests whether the slope and interc ept of the model are significantly different from zero. The coefficient of determination is a measure of the variance in the de pendent variable that is explained by the model. A plot of the residuals versus the independent variable can be used to judge if the assumption of constant variance is met. Additional plots of residuals versus other variables can also be instructive. For example, a time-series plot of the residuals can be used to assess whether or not the residuals vary seasonall y. Additional diagnostics can be run to identify outliers and test for leverage or influential points. Data points that are identified by these additional diagnostics should be further investigated to determin e if they are the result of a data entry error or other problems that merit removing them from the analysis. The independent variables used in the model bu ilding process included lo adings, concentrations, and estimates of residence time. The loadings da ta included monthly hydrologic, TN, and TP loads as well as cumulative total loads extending from two to six months (e.g., 2-month cumulative TN load = TN load current month + TN load one- month prior). The water quality constituents included TN and TP concentrations along with num erous other constituents. The results of the analyses for each segment are presented below. 

# VI-3 Roberts Bay A series of bivariate plots were examined to investigate relationships between chlorophyll a and other potential explanatory variables. TN concen tration was identified as the variable that makes that greatest contribution to explai ning the variability in chlorophyll a concentrations in Roberts Bay. As can be seen in Figure VI-1, th ere is a pattern of increasing chlorophyll a concentrations with increasing TN concentrations.

# 50 Figure VI-1. Relationship between monthly average chlorophyll a and TN concentrations in Roberts Bay. 

# A regression model between chlorophyll a and TN concentrations was developed and the residuals from this model were examined to identify any othe r explanatory variables that might contribute to the overall variance accounted for by the model. The residual analysis revealed a seasonal difference in residuals. Specifically, given the same TN concentrations, higher chlorophyll a concentrations can be expected during the wette r, warmer summer months (July-October) than during the remainder of the year. Therefore, a se asonal term was added to the regression equation. The season term is a dummy variable which equals one during July-October and zero other months of the year. The final regression equation is: [Chlorophyll a ] = -5.73 + (27.07 * [TN]) + (3.41 * season)
The model was fit with 133 observations and resulted in an R 2 

# value of 0.62. The regression was highly significant with a probability of a greater |F| value of < 0.0001. The slope and parameter coefficients were also highly significant. A plot of predic ted versus observed chlorophyll a concentrations is presented in Fi gure VI-2. The fit is generally go od with some overestimation at low concentrations and underestimation at hoghe r levels. Residual plots for the Roberts Bay chlorophyll a regression model are presented in Appendix 5. 

# VI-4 Little Sarasota Bay A series of bivariate plots were examined to investigate relationships between chlorophyll a and other potential explanatory variables in Little Sara sota Bay. TN concentration was identified as the variable that makes that greatest contributi on to explaining the variability in chlorophyll a concentration. As can be seen in Figure VI-3 there is a pattern of increasing chlorophyll a concentrations with increasing TN concentrations.

# 51 Figure VI-2. Predicted versus observed chlorophyll a concentrations for Roberts Bay (R 2 

# =0.62). 

# A regression model between chlorophyll a and TN concentrations was developed and the residuals from this model were examined to identify any othe r explanatory variables that might contribute to the overall variance accounted for by the mode l. As was found in Roberts Bay, the residual analysis revealed a seasonal difference in residuals. Specifically, given the same TN concentrations, chlorophyll a concentrations can be expected to be higher in Little Sarasota Bay during the wetter, warmer summer months (July-Octobe r) than during the remainder of the year. Therefore, a seasonal term was added to the regression equation. The season term is a dummy variable which equals one during July-October and zero other months of the year. The final regression equation is: [Chlorophyll a ] = -4.48 + (21.59 * [TN]) + (2.97 * season)

Figure VI-3. Relationship between monthly average chlorophyll a and TN concentrations in Little Sarasota Bay.

# 52 

# The model was fit with 133 observations and resulted in an R 2 

# value of 0.57. The regression was highly significant with a probability of a greater |F| value of < 0.0001. The slope and parameter coefficients were also highly significant. A plot of predic ted versus observed chlorophyll a concentrations is presented in Figure VI-4. Re sidual plots for the Little Sarasota Bay chlorophyll a regression model are presented in Appendix 5.

Figure VI-4. Predicted versus observed chlorophyll a concentrations in Little Sarasota Bay (R 2 

# =0.57).



# VI-5 Blackburn Bay A series of bivariate plots were examined to investigate relationships between chlorophyll a and other potential explanatory variables. TN concen tration was identified as the variable that makes that greatest contribution to expla ining the variability in chlorophyll a concentration. As can be seen in Figure VI-5, there is a pattern of increasing chlorophyll a concentrations with increasing TN concentrations. A regression model between chlorophyll a and TN concentrations was developed and the residuals from this model were examined to identify any othe r explanatory variables that might contribute to the overall variance accounted for by the model. Similar to both Roberts Bay and Little Sarasota Bay, this analysis revealed a seasonal difference in residuals. Specifically, given the same TN concentrations, chlorophyll a concentrations can be expected to be higher in Blackburn Bay during the wetter, warmer summer months (July-October) than during the remainder of the year. Therefore, a seasonal term was added to the regression equation. The season term is a dummy variable which equals one during July-October and zero other months of the year. The final regression equation is: [Chlorophyll a ] = -3.55 + (23.72 * [TN]) + (1.73 * season)

# 53 Figure VI-5. Relationship between monthly average chlorophyll a and TN concentrations in Blackburn Bay.


# The model was fit with 133 observations and resulted in an R 2 

# value of 0.73. The regression was highly significant with a probability of a greater |F| value of < 0.0001. The slope and parameter coefficients were also highly significant. A plot of predic ted versus observed chlorophyll a concentrations is presented in Figure VI-6. Residual plots for the Blackburn Bay chlorophyll a regression model are presented in Appendix 5.

Figure VI-6. Predicted versus observed chlorophyll a concentrations in Blackburn Bay (R 2 

# =0.73). 

# VI-6 Sarasota Bay In order to investigate potential relationships between chlorophyll a and explanatory variables in Sarasota Bay, a series of bivariate plots were examined. TN concentration was identified as the

# 54 

# variable that makes the greatest contributi on to explaining the variability in chlorophyll a concentrations in Sarasota Bay. As expected, there is a pattern of increasing chlorophyll a concentrations with increasing TN concentrations (Figure VI-7). As in the regressions developed for Roberts Bay, Little Sarasota Bay, and Blackburn Ba y, initial efforts revealed a seasonal difference in residuals. This indicates that given the same TN concentration, higher chlorophyll a concentrations are expected during the summer months. Therefore , a seasonal term was added to the regressionequation. The season term is a dummy variable which equals one during the wet season (JuneOctober) and zero other months of the year. Unlike Roberts Bay, Little Sarasota Bay, and Black burn Bay, Sarasota Bay is a substantially larger system with greater spatial variability in TN concen trations. Specifically, TN concentrations in the northern portion of the bay (Figure VI-8) are greater than those in the southern portion (Table VI-1). In contrast, there is less spatial variability in the chlorophyll a concentrations. As a result, given the same TN concentrations, higher chlorophyll a concentrations are found in the southern portion of the bay. Therefore, a region term was added to the regression equation to account for the spatial differences in TN and chlorophyll a concentrations in Sarasota Bay. 

# Further analysis of the residuals from th e regression model revealed that color also contributed to explaining the variation in chlorophyll a and was added to the regression equation. The final regression equation obtained is: [Chlorophyll a ] = -1.06 + (3.58 * [TN]) + (0.32 * color) + (2.03 * season) – (4.84 * region)

Figure VI-7. Relationship between monthly average chlorophyll a and TN concentrations in Sarasota Bay.

# 55 Figure VI-8. Northern and southern portions of the Sarasota Bay segment.

Table VI-1. Comparison of water quality within Northern and Southern Sarasota Bay. Values represent medians for the period 1998-2009. Variable Northern Sarasota Bay Southern Sarasota Bay Chlorophyll a (μg/l) 5.2 3.4 TN (mg/l) 0.56 0.28 Color (PtCo units) 20 10



# The model was fit with 156 observations and resulted in an R 2 

# value of 0.67. The regression was highly significant with a probability of a greater |F| value of < 0.0001. The slope and parameter coefficients were also significant. A plot of predicted versus observed chlorophyll a concentrations is presented in Figure VI-8. Residual plots for the Sarasota Bay chlorophyll a regression model are presented in Appendix 5. Northern Region

# 56 Figure VI-8. Predicted versus observed chlorophyll a concentrations in Sarasota Bay (R 2 

# =0.67).



# VI-7 Palma Sola Bay A series of bivariate plots were examined to investigate relationships between chlorophyll a and other potential explanatory variables in Palm a Sola Bay. Specifically, examination of the relationship between chlorophyll a concentrations and both TN concentrations and loads were examined. As can be seen in Figures VI-9 and VI-10, there is no apparent relationship between chlorophyll a concentrations and either TN concentrations or loads. A similar lack of relationships was found for TP concentrations and loads, as well as a series of cumulative loading.

Figure VI-9. Relationship between monthly average chlorophyll a and TN concentrations in Palma Sola Bay.

# 57 Figure VI-10. Relationship between monthly average chlorophyll a and TN loading in Palma Sola Bay. 

# Several other analytical tools were applied to discern if a quantitative relationship between chlorophyll a concentrations and either TN concentrati ons or loads could be found. Specifically, various applications of both logistic regressi on techniques and changepoint analyses were investigated. Logistic regression was used to predict the probability of a chlorophyll a concentration greater than the threshold value of 11.8 μg/l for Palma Sola Ba y as a function of TN concentration. A season term was incorporated to account for the differen tial effects of TN concentration on phytoplankton production depending on water temperature and photoperiod. One hundred and seventy-one observations were used in th e regression and 49 chlorophy ll exceedances (i.e., chlorophyll a > 11.8 μg/l) occurred in the dataset. The resu lting logistic regression equation was:

( 1| )

( 1| ) 

# ( ) 2.1521 2.0486* 0.74*1( )

1 y x

y x 

# p LOG TN Wet p 

 

#   


The model R 2 

# was 0.24 and suggested that the odds of a value exceeding the threshold during the wet season was more than twice [i.e., e (0.74) 

# ] that of the dry season (Figure V-11). In order to use logistic regression for prediction, one must assign a probability cutpoint from which to define an exceedance. The SAS program (S AS, 2010) uses a jackknife routine to estimate the probability cutpoint that results in the highest predictive accu racy of the model and therefore confidence in “making the right call”. Applying this jackknife proce dure to the TN and chlorophyll a concentration data for Palma Sola Bay identified a probability cutpoint of 0.45 which resulted in 76% classification success (sensitivity=47% and specificity=87%). Based on these results, a TN concentration that is predicted to result in a chlorophyll a concentration exceedance in the wet season is 0.57 mg/l and in the dry season 1.31 mg/l. Using these va lues and calculating a weighted mean TN concentration results in an annual average annual TN concentration of 1.06 mg/l. It is important to

# 58 

# note that these estimates do not include uncerta inty in the model estimates which may be substantial, therefore the results should be applied with a degree of caution.

Figure V-11. Predicted probabilities of a chlorophyll a value greater than 11.8 in wet and dry season in Palma Sola Bay. Horiz ontal line indicates cutpoint probability for assigning a predicted value as an exceedance. 

# Changepoint analysis was performed to identify a potential threshold TN value that was associated with a non-linear increase in chlorophyll a concen trations. Changepoint analysis performs an iterative search through the data so rted in increasing order of TN values to identify a “changepoint” in the relationship that maximizes the difference in chlorophyll concentrations between two groups of data. In this way a threshold value for TN is identified. No a priori threshold is specified. The decision tree approach defines the breakpoint as that which maximizes the difference by minimizing the p value associated with the F test. The poi nt in the covariate (TN concentration) at which the p value is minimized, after adjustment for multiple comparisons, is assigned as the breakpoint defining the split of the chlorophyll data into 2 groups. Once the first split is made the process continues to test for subsequent splits th at are conditional on the fir st split. This is called “conditional inference” or “conditional probability analysis” which has been popularized recently by the USEPA as a potential approach for establishing numeric nutrient criteria. For this analysis, the state threshold for chloroph yll-a in marine waters (11 μg/l) was used as a criterion value for evaluating the potential of the id entified changepoint value of TN to serve as a potential numeric nutrient criterion. That is, if the identified changepoint resulted in a group of chlorophyll data with an average value above 11 μg/l then the TN changepoint was deemed as a potential value for numeric nutrient criterion development. The results of changepoint analysis for Palma Sola Bay is provided in Figure V-12. A statistically significant TN changepoint value of 0.756 mg/l was identified as the value that maximized the difference in the distribution of chlorophyll a concentrations between two groups. The average

# 59 

# chlorophyll a concentration when TN concentrations were below 0.756 mg/l was 7.69 μg/l and the average chlorophyll a concentration when TN concentrations were above 0.756 g/l was 11.6 μg/l. Since the average chlorophyll a concentration in the high TN group was above the state threshold, we consider this TN value to be poten tially meaningful in allowing Palma Sola Bay to continue to meet its designated uses.

Figure V-12. Results of changepoint analysis in Palma Sola Bay with distribution of chlorophyll a values displayed in boxplots and the TN changepoint identified as 0.75. Mean Chlorophyll a 7.7 μg/l Mean Chlorophyll a 11.6 μg/l 

# Palma Sola Bay

Decision Tree

# 60 

# VII. Recommended SBEP Numeric Nutrient Criteria We have applied the stressor-response relationships described in Section VI to estimate draft numeric nutrient criteria for each SBEP segment. The strategy for developing the numeric nutrient criteria is based on the chlorophyll a thresholds identified in Section III and the quantitative relationships between chlorophyll a and nutrients derived in Section VI. The following describes the approach used. 

# VII-1 Roberts, Little Sar asota, and Blackburn Bays The stressor-response relationships for Roberts Bay, Little Sarasota Bay, and Blackburn Bay that were identified in Section VI indicated very similar responses in chlorophyll a concentrations to changes in nutrients. Specifically, two terms, TN concentration and season, explained more than 60% of the variation in the chlorophyll a data. For each of these segments, the regression was used to estimate the TN concentrations that correspond to the chlorophyll a thresholds identified in Section III. This resulted in an estimated TN concentration for each season. The annual me an of the seasonally-specific TN concentrations was calculated by weighting for the number of months in each season. This weighted annual mean TN concentration is that TN concentra tion that corresponds to the chlorophyll a threshold concentration, and therefore is the proposed numeric nutrient criterion for each segment. Figures VII-1 – VII-3 present comparisons of the proposed numeric criteria for Roberts Bay, Little Sarasota Bay, and Blackburn Bay, expressed as an annual geometric mean TN concentration, to the recent ambient geometric mean TN concentratio ns measured in each segment. The geometric means are used to achieve consistency with the appr oach used by EPA in the proposed freshwater numeric nutrient criteria.

Figure VII-1. Comparison of the proposed TN criterion to observed TN concentrations (expressed as geometric means) in Roberts Bay. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009[TN](mg/l)



### Ambient [TN] (mg/l) [TN] Criterion (mg/l) 

# ROBERTS BAY

# 61 Figure VII-2. Comparison of the proposed TN criterion to observed TN concentrations (expressed as geometric means) in Little Sarasota Bay.

Figure VII-3. Comparison of the proposed TN criterion to observed TN concentrations (expressed as geometric means) in Blackburn Bay.



# VII-2 Sarasota Bay As shown in Section VI, the relationship between chlorophyll a concentrations and nutrients in Sarasota were more complex than those observed in Roberts Bay, Little Sarasota Bay, or Blackburn Bay. This resulted from the spatial variability with in Sarasota Bay and the influence of color on the relationship between chlorophyll a concentrations and TN concentrations in that segment. Therefore, application of the regression derived fo r Sarasota Bay to estimate the proposed numeric 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009[TN](mg/l)



### Ambient [TN] (mg/l) [TN] Criterion (mg/l) 

# LITTLE SARASOTA BAY

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009[TN](mg/l)



### Ambient [TN] (mg/l) [TN] Criterion (mg/l) 

# BLACKBURN BAY

# 62 

# nutrient criterion is more complex. Since color influences the relationship between chlorophyll a concentrations and TN concentrations, the TN concentration that corresponds to the threshold chlorophyll a concentrations for Sarasota Bay will vary from year-to-year depending upon the ambient color observed in a year. To estimate the TN concentration that corresponds to the threshold chlorophyll a concentrations for Sarasota Bay, the mean color for each region and season was calculated for a given year. This mean color was used to calculate the TN concen tration for each region and season. The annual mean of these TN concentrations was calculated by weighting for the number of months in each season, as was done for Roberts Bay, Little Sarasota Bay, or Blackburn Bay. This weighted annual mean TN concentration is that TN concentr ation that corresponds to the chlorophyll a threshold concentration for a given year. These mean annu al TN concentrations are the proposed numeric nutrient criterion for Sarasota Bay. Figures VII-4 presents a comparison of the proposed numeric criteria for Sarasota Bay expressed as an annual mean TN concentration, to the rece nt ambient geometric mean TN concentrations measured in Sarasota Bay.

Figure VII-4. Comparison of the proposed TN criterion to observed TN concentrations (expressed as geometric means) in Sarasota Bay.



# VII-3 Palma Sola Bay No significant quantitative relationship was found be tween chlorophyll a conc entrations and either the TN or TP concentrations or loadings in Palm a Sola Bay. Therefore, the approach to derive a numeric nutrient criterion for Palma Sola Bay will necessarily differ from that used for the other SBEP segments. 0 0.2 0.4 0.6 0.8

1 1.2 1.4 1.6

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009[TN](mg/l)



### Ambient [TN] (mg/l) [TN] Criterion (mg/l) 

# SARASOTA BAY

# 63 

# The SBEP water quality subcommittee of the TAC c onsidered three potential candidate methods for estimating the TN criterion for Palma Sola Bay:

 The logistic regression results suggested wet a nd dry season TN concentrations of 0.57 mg/l and 1.31 mg/l, respectively. The annual mean, weighting for season, gives a result of 1.06 mg/l as a candidate TN criterion. Note th at the logistic model fit was weak – r 2 

# =0.25.

 The changepoint analysis identified a breakpoint in the TN concentrati ons of approximately 0.76 mg/l.

 Following the logic used by the subcommittee to establish chlorophyll a concentrations for the SBEP segments

- the mean TN concentration for the 2001-2005 period was 0.74 mg/l

- the standard deviation of the annual mean TN concentrations for the period of record was 0.19 mg/l

- therefore, this method results in a candidate TN criterion of 0.93 mg/l. All three potential candidate methods give relatively similar results. The subcommittee recommended the third option – i.e., that based on the 2001-2005 ambient TN data. The full TAC concurred with the subcommittee’s recommendation on 23 July 2010. Figures VII-5 presents a comparison of the propos ed numeric criteria for Palma Sola Bay expressed as an annual mean TN concentration, to the re cent ambient geometric mean TN concentrations measured in Palma Sola Bay.

Figure VII-5. Comparison of the proposed TN criterion to observed TN concentrations (expressed as geometric means) in Palma Sola Bay. 0 0.2 0.4 0.6 0.8

1 1.2

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008[TN](mg/l)



### Ambient [TN] (mg/l) [TN] Criterion (mg/l)

# 64 

# References Boynton, W.R., W.M. Kemp, and C.W. Keefe. 1982. A comparative analysis of nutrients and other factors influencing estuarine phytoplankton, p. 69-90. In: V.S. Kennedy (ed.), Estuarine Comparisons. Academic Press, New York. Chapra, S. C. 1997. Surface Water-Qua lity Modeling. WCB McGraw-Hill, Boston Massachusetts. 843p. Dillon, K.S. and J.P. Chanton. 2008. Nitrogen stable isotopes of macrophytes assess stormwater nitrogen inputs to an urbanized estuary. Estuaries and Coasts . 31: 360-370. Florida Department of Environmental Protection (FDEP). 2005. Nutrient TMDL for Roberts Bay (WBID 1968D) . Florida Department of Environmenta l Protection, Tallahassee, FL. 55 pp. Florida Department of Environmental Protecti on (FDEP). 2000. Memorandum: Updated Guidance on Implementation of the Gri zzle-Figg Legislation (Section 40 3.086,Florida Statutes). 5p. Hagy, James D., Lawrence P. Sanford, and Walter R. Boynton. 2000. Estimation of Net Physical Transport and Hydraulic Residence Times for a Coasta l Plain Estuary Using Box Models. Estuaries. 23:328-340. Hirsch, R.M., J.R. Slack, and R.A. Smith. 1982. Techniques of trend analysis for onthly water quality data. Water Resources Research. 18:107-121. Hirsch, R.M. and J.R. Slack. 1984. A nonparametr ic trend test for seasonal data with serial dependence. Water Resources Research. 20:727-732. Howarth, R.W. 1988. Nutrient Limitation of Ne t Primary Productivity in Marine Ecosystems. Annual Review of Ecology and Systematics . 19:89-110. 

# Janicki, A., M. Dema, R. Nijbroek. 2009. Seagrass Targets for the Sarasota Bay Estuary Program. Prepared for the Sarasota Bay Estuary Program. Prepared by Janicki Environmental, Inc. Janicki Environmental, Inc. 2010a. Chlorophyll E ndpoints to Support the Development of Numeric Nutrient Criteria for the Sarasota Bay Estuary Pr ogram. Prepared for the Sarasota Bay Estuary Program. Janicki Environmental, Inc. 2010b. Empirical Appro aches to Establishing Numeric Nutrient Criteria for Southwest Florida Estuaries. Prepared for th e Tampa Bay Estuary Program, Sarasota Bay Estuary Program, and Charlotte Harbor National Estuary Program. Jones Edmunds & Associates. 2009. Sarasota County Pollutant Loading Model Development (W552) SIMPLE-Monthly Design Report. Prepared for Sarasota County and Southwest Florida Water Management District. 49pp.

# 65 

# Lowrey, S. 1992. Physical and chemical proper ties – Bay water and sediment quality. pp. 4.1 – 4.20, In: (P.Roat, C. Ciccolella, H. Smith, and D. Tomasko, eds.). Sarasota Bay: Framework for Action . Sarasota Bay National Estuary Program, Sarasota, FL.
Natural Resources Conservation Service. 1986. Tec hnical Release 55: Urban Hydrology for Small Watersheds. U.S. Department of Agriculture. National Research Council, 2000. Clean Coastal Wate rs: Underdstanding and Reducing the Effects of Nutrient Pollution. National Academy Press, Washington, DC. Pennock, J.R., J.N. Boyer, J.A. Herrera-Silveira, R.I. Iverson, T.E. Whitledge, B. Mortazavi, F.A. Comin. 1999. Nutrient behavior and phytoplan kton production in Gulf of Mexico estuaries. In: Biogeochemistry of Gulf of Mexico Estuaries. Eds. T.S Bianchi, J.R. Pennock, and R.R. Twilley. John Wiley & Sons. Poor, N. 2000. Tampa Bay Atmospheric Depositi on Study (TBADS) Final Interim Report: June 2000. Tampa Bay Estuary Program Technical Publication #06-00. Pribble, J.R. , D.L. Wade, A.J. Janicki, A.P. Squi res, H. Zarbock, R. Montgomery and G. Morrison. 1997. Empirical and mechanistic approaches to es tablishing pollutant load reduction goals in the tidal Peace and Myakka rivers. Final report to the Southwest Florida Water Management District. Pribble, R., A. Janicki, H. Zarbock, S. Janick i, and M. Winowitch. 2001. Estimates of Total Nitrogen, Total Phosphorus, Total Suspended Solid s, and Biochemical Oxygen Demand Loadings to Tampa Bay, Florida: 1995-1998. Prepared by Janicki Environmental. Prepared for Tampa Bay Estuary Program. Tampa Bay Estuary Program Technical Publication #05-01. Sarasota Bay Estuary Program (SBEP). 2010. State of the Bay. Prepared by Sarasota Bay Estuary Program. SAS 9.2 (TS2M3). 2010. SAS Institute, Inc. Cary, North Carolina. Tomasko, D., Alderson, M. Clark, P. Culter, J., Dixon, K., Edwards, R., Estevez, E., Heyl, M., Lowrey, S., Sheng, P., and J. Stevely. 1992. Technical synthesis of Sarasota Bay. Pp. 14.1-14.16. In: (P.Roat, C. Ciccolella, H. Smith, and D. Tomasko , eds.). Sarasota Bay: Framework for Action

. Sarasota Bay National Estuary Program, Sarasota, FL. Tomasko, D.A., Dawes, C.J., and M.O. Hall. 1996. The effects of anthropogenic nutrient enrichment on turtle grass ( Thalassia testudinum ) in Sarasota Bay, Florida. Estuaries 19: 448-456. Tomasko, D.A., Corbett, C.A., Greening, H.S., a nd G.E. Raulerson. 2005. Spatial and temporal variation in seagrass coverage in Southwest Florida: assessing the relative effects of anthropogenic nutrient load reductions and rainfall in four contiguous estuaries. Marine Pollution Bulletin . 50: 797-805.

# Appendix 1. Sarasota Bay Estuary Program Comments on EPA Proposed Freshwater Numeric Nutrient Criteria

# Sarasota Bay Estuary Program (SBEP) response to the EPA’s Proposed Water Quality Standards for the State of Florida’s Lake s and Flowing Waters and Methodology for Deriving Downstream Protection Values for Sarasota Bay, FL

These comments are provided for EPA’s review a nd use in developing the Sarasota Bay Estuary Program’s (SBEP) numeric nutr ient criteria for Sarasota Bay. Additional comments and recommendations will be provided through the Flor ida Department of En vironmental Protection (FDEP) in June 2010. Background Sarasota Bay is a fifty mile long coastal lagoon on the southwest coast of Florida (Figure 1). It is comprised of one large bay segment (Big Sara sota Bay) and several smaller embayments including Palma Sola Bay in the north and a se ries of three contiguous embayments (Roberts Bay, Little Sarasota Bay, and Blackburn Bay) to the south. The Bay has four inlets or passes (Venice Inlet, Big Sarasota Pass, New Pass a nd Longboat Pass). The SBEP area is bounded to the north by Anna Maria Sound, whic h opens into Tampa Bay and to the south by Venice Inlet. There are numerous, small tidal creeks that ente r the bay along the eastern shoreline, ranging in size from the largest (Phillippi Creek: drainage area of 36,417 acres) to the smallest (Palma Sola Creek: drainage area of 900 acres). The wate rshed is highly devel oped and consists of agricultural, residential, commerci al and light indu strial land uses. Circulation is primarily driven by tidal exchange with the Gulf of Mexico. Big Sarasota Bay circulation is forced by the tides at Anna Maria Sound, Longboat Pass, New Pass and Big Pass. Tidal circulation in Little Sarasota Bay is forced by tides at Venice Inlet and the Intracoastal Waterway running through the middle of the bay. The closing of Midnight Pass in Little Sarasota Bay in 1983 permanently altered the ci rculation in the three lower embayments. History of Nutrient Management in Sarasota Bay Sarasota Bay was named an “Estuary of Nationa l Significance” in the Wa ter Quality Act of 1987 and was formally designated as a National Es tuary Program (NEP) in 1989. The Program’s Comprehensive Conservation and Ma nagement Plan (CCMP), which provides specific actions to be implemented by the community to reduce poll utants (including nutrien ts) and restore lost habitat, was signed in 1995. In 2004, the SBEP became an independent State Agency with authority to oversee water qual ity management and protection. Sarasota Bay is a nitrogen limited system (Lowrey, 1992; FDEP, 2005). Ratios between total nitrogen (TN) and total phosphorus (TP) in Sa rasota Bay are typically well below 10 (i.e., Lowrey, 1992), which is consistent with presumed nitrogen limitation. Roberts Bay (a segment of Sarasota Bay- see Figure 1) had a median TN:TP ratio of 2.4, which also indicates strong nitrogen limitation of phytopl ankton growth (FDEP, 2005). From its inception, the SBEP recognized that wa stewater and stormwat er were the primary sources of anthropogenic nitrogen input (the othe r source being atmospheri c deposition) entering

# the bay. As such, wastewater treatment a nd reclamation and stormwater treatment and prevention became the two most important action items in the CCMP with the goal of reducing nitrogen inputs to the bay by 48%. Each of these action items contained a number of specific elements designed to reach this nu trient reduction goal (CCMP, 1995).

Figure 1. Map of Sarasota Bay, its watershed and tributaries.

# Through the cooperation of SBEP partners - lo cal municipal and county governments, the Southwest Florida Water Management Distri ct (SWFWMD), the Florida Department of Environmental Protection (DEP) and the Envi ronmental Protection Agency (EPA) - in implementing these action items, we have documen ted significant improvements in water quality and the resultant recovery of seagrass throughout the estuary over the past twenty years. The highlights of these improvem ents and recovery are:

1. Nitrogen loads- using the EPA approved Watershed Management Model- to Sarasota Bay have been reduced by 46% since 1988 (Tomasko et al ., 2005). Author’s note: recent estimates of TN load reduction using WMM approximate 64% (Tomasko et al, 2009, Estuarine Research and Coastal Federati on Conference, Portland Oregon) - this information has not been published.

2. As of 2008, seagrass acreage is 24% hi gher than 1950 acreage. (Figure 2).
3. Total seagrass acreage (2008) has in creased 46% since 1988 (Figure 2).

4. Continuous seagrass beds have in creased 180% since 1988 (Figure 2).
5. Sarasota Bay is meeting designated uses with respect to nutrients. Bay scallops returned to Sarasota Bay seagrass beds in 2008. Fish eries data show high a bundances of juvenile fish within seagrass beds in all bay segments (Serviss and Sauers, 2003). These findings support the attainment of full aquatic life support and use.

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000

1950 1988 1994 1999 2001 2004 2006 2008 YearSeagrass (Acres)



## Continuous Patchy 

# Figure 2. Total seagrass cover (in acre s) for Sarasota Bay. (SWFWMD, 2008).

# Nitrogen Reduction Measures Declines in total nitrogen (TN) concentrations and loads are a result of extensive capital improvement projects undertaken by our partne rs ($375 million). Pollution reduction efforts have focused on three major tributaries and co astal areas: Phillippi Creek; Whitaker Bayou, and Manatee County (coastal wastewater seepage from agriculture reuse and Bowlees Creek). Phillippi Creek- South Bay Phillippi Creek drains 38% of the Sarasota Bay watershed. Annual TN c oncentrations averaged 3.12 mg/l from 1970 through 1988 (Figure 3). Nitr ogen loading from Phillippi Creek has decreased approximately 60% since that time. Thes e nitrogen load reducti ons are the result of three major infrastructure programs: 1) the construction of a major watershed stormwater treatment facility, 2) constr uction of an AWWTP, allowing for the removal of nineteen ineffective WWTPs, and 3) a major septic ta nk replacement program within the watershed.

Figure 3. Nitrogen concentrations in Phillippi Creek, the main tributary to Sarasota Bay. (PBSJ, 2009). Whitaker Bayou- Central Bay Whitaker Bayou, a tributary which was once the larg est anthropogenic contribu tor of nitrogen to Sarasota Bay (Figure 4), has seen a ten-fold reduction in nitrogen loads due to the following improvements: 1) upgrading the City of Sarasota wastewater treatment plant to AWT standards, 2) expansion of the City’s reclaimed water sy stem, 3) converting rema ining areas of Whitaker Bayou from septic systems to central sewer, and 4) consolidation of the remaning WWTPs in the watershed. In 2016, the City is expected to ceas e discharging wastewater into Whitaker Bayou.

# Figure 4. Nitrogen loads to Whitaker Bayou. (Tomasko et al ., 2005).

Manatee County- North Bay Manatee County’s southwest regional WWTP (1 5 mgd) in north Sarasota Bay no longer discharges to the surface waters of the state. This was accomplished through 1) construction of a tail water recovery system in 1980, 2) permitting deep well injection of wastewater in 1991, and 3) wastewater reuse. No septic tanks or packag e plants remain in service in the Sarasota Bay watershed portion of Manatee County and there is no direct discharge of wastewater in the northern Bay. The Bowlees Creek watershed has seen significant water quality improvements as a result of several wastewater and stormwater treatment proj ects. First, Lake Brennan was expanded into a regional stormwater treatment system. Sec ond, the stormwater drainage system at the Sarasota/Bradenton Airport was reconstructed utilizing mode rn water quality treatment technologies. Finally, sewer syst ems were replaced or upgraded in the lower portions of the watershed. Educational Programs The SBEP and partners have developed broad sc ale adult and in-school educational programs to promote pollution prevention and stewardshi p including: Florida Friendly Landscaping, Neighborhood Environmental Stewardship Teams a nd Water Wise initiatives. Local water use has been reduced to 80 gallons/per person/day.

# Florida Yards are required in all new developm ent in approximately 80% of the watershed. Substantial public relations initiatives have been aimed at reducing water consumption and pollution abatement. Adoption of Local Fertilizer Ordinances Finally, Sarasota County and the Cities of Sara sota and Longboat Key rece ntly adopted fertilizer ordinances which prohibit, among other things, fertilizer application dur ing the summer (wet) months. This ordinance covers 80% of the Sarasota Bay watershed.
Numeric Nutrient Criteria Setti ng in Sarasota Bay: Role of the Sarasota Bay Estuary Program For the past several years, the SBEP has been wo rking with its partners to establish local water quality targets for the maintenance and restoratio n of seagrasses. To date, we have held a number of technical advisory committee meetings specifically to address th is issue not only as a response to the impending criteria being develope d by the EPA, but also for our partners and stakeholders as a framework to better understand the local response of seagrasses to nutrient loads so that we may better manage our estuary a nd its watershed. The specific role of the SBEP is to facilitate information exchange, modeling and technical data in support of EPA’s rule making process. The SBEP s upports third party review. We recognize the timeliness for completing this ta sk as it relates to th e ongoing development of numeric nutrient criteria for estuar ine and coastal waters in Flor ida by the EPA and FDEP. Their schedule calls for draft criteria to be established by January 2011. We have set an aggressive timetable in order to provide preliminary re sults by early June, 2010, fo r consideration by the EPA as site-specific criteria based on the best local data and knowledge. The basic strategy for establishing water quality and loading criteria follows that utilized over the past 13 years by the Tampa Bay Estuary Progr am (TBEP) and the Nitrogen Management Consortium. The paradigm depends upon knowledge of the quantitative relationships between light attenuation and ambient wa ter quality (e.g., chlorophyll a ) and between chlorophyll concentrations and nutrient load ing. Empirical modeling technique s are being used to identify these quantitative relationships. The objectives of the project for setting nutrient criteria are:

 To develop a database of nutrient loads a nd concentrations for each major bay segment for the period 1989-2008 and for a future scenario and updating load estimates based on a new watershed loading model.

 To define the quantitative re lationships between chlorophyll a concentrations and light attenuation for each bay segment;

 To estimate the chlorophyll thresholds to m eet the light attenuati on and seagrass targets for each bay segment;

 To define the quantitative relationships between nutrient lo ading and chlorophyll a concentrations for each bay segment; and

#  To estimate the numeric nutrient criteria, i.e ., the nutrient loading consistent with the chlorophyll a thresholds, for each bay segment. These estimates will incorporate additional hydrological factor s, including circulation and residence time, and water clarity parameters.
Our initial efforts have resulted in establis hing seagrass targets for each of the main bay segments (Table 1). Seagrass targets were base d on either historical ( 1950) coverage or the average of the two most recent surveys (2004 - 2006) . These targets will be re-evaluated every five years. This process was vetted at the technical and manage ment levels of the program; in May 2009, the SBEP policy board formally appr oved and adopted the seagrass acreages as restoration goals.
The SBEP has also established and approved interim chlorophyll a targets (also Table 1). The period 2001 – 2005 was selected as the performa nce window to include multiyear conditions antecedent to the most recent seagrass surveys. This time period also included years that had a wide range in annual rainfall. Since the averag e seagrass coverage from 2004 – 2006 for all bay segments are at or above 1950 coverage, water quality conditions from our performance window must be sufficient for seagrass to me et the designated target acreages. Historic chlorophyll thresholds (FAC 62-303) we re established in 2004 by FDEP to evaluate nutrient impairment by major bay segment as identified in the EPA 1998 303d report. FDEP evaluated impairment in 2005, 2007 and 2009 using these historic chlo rophyll thresholds. All Sarasota Bay segments have been de-listed by the FDEP for nutrients (chlorophyll a ).

Table 1. Sarasota Bay Seagrass and Chlorophyll a Targets by Bay Segment. Chlorophyll a Values Represent the Average of th e Annual Means for the Period 2001 – 2005.

Sarasota Bay Segment Seagrass Target (Acres) Chlorophyll a Target (μg/L) Palma Sola 1,031 8.3 Sarasota Bay 7,269 5.0 Roberts Bay 348 7.6 Little Sarasota Bay 702 7.2 Blackburn Bay 447 5.6 TOTAL 9,997

SBEP Concerns with the Proposed Rule The SBEP has concerns regardi ng the draft rule for numeric nut rient criteria for lakes and streams within the Sarasota Bay watershed. This rule is based on the initial premise that

# Sarasota Bay loads are above its assimilative capacity. However, Sarasota Bay is below the chlorophyll thresholds in each of its bay segmen ts and no segment has been deemed “impaired” for nutrients by the FDEP. Additionally, seagra ss acreages are at or above their targets. The SBEP approach to establishing the approved lo ading targets is similar to the approach used in Tampa Bay (Greening and Janicki, 2006; Janicki and Wade, 1996) and follows EPA’s technical guidance which states th at quantifying stressor-response relationships is the preferred approach in establishing numeric nutrient criteria. Specifically, the SBEP will be defining these quantitative relationships between nutrient loads and chlorophyll levels in all Sarasota Bay segments. There is considerable evidence to dem onstrate that existing loads to Sarasota Bay are providing for the full aquatic lif e protection and support for all designated uses related to nutrients in the estuary. There are other concerns that deal specifically with the application of the USGS Spatially Referenced Regression on Watershed Attributes (SPARROW) model for the southeastern US. This model was used to calculate both existing and baseline loads for Sarasota Bay that were used to estimate protective loads for Sarasota Bay. While the SPARROWmodel may work well for its expressed purpose, i.e., to examine landscap e characteristics that influence delivery of nitrogen from sources within the watersheds in the southeastern US, its application to the Sarasota Bay watershed is questionable. The Sarasota Bay load estimates that are being developed are driven by local data sources (particularly pointsources, atmospheric deposition, and fertilizer shipping), while the SPARROW co efficients are based on regional (southeastern US) data. Thus, the scaling of SPARROW to such a small basin as Sarasota Bay needs to be validated. Estimates using SPARROW do not fully reflect th e time-varying loads to an estuary and its resulting response to those loads. Rather, the downstream load is based on a load normalized to the hydrologic conditions experienced in 2002. The proposed DPV for TN (.54 mg/l) is less than the natural concentrations cited in the Lemon Bay model by EPA. Finally, the SBEP has concerns with the met hodology for proposed downstream protection value (DPV) for estuarine protection for Sarasota Ba y. The proposed DPV is inappropriate based on the fact that current nutri ent loadings to the bay are not above their assimilative capacity based on recent trends and current acr eages of seagrass, the primary response variable. The proposed TN concentration- 0.54 mg/L- for downstream prot ection is less than th e concentration from natural areas derived by the EPA using the Le mon Bay Watershed Model. The SBEP will propose an alternative quantitati ve methodology based on scientifica lly defensible approaches, to derive and quantify the protective load to Sarasota Bay and its tributary streams.

# SBEP Recommendations In conclusion, we have summarized the site-speci fic work that has been completed for Sarasota Bay, including the establishmen t of seagrass and chlorophyll a targets, the ongoing development of quantitative relationships among seagrasses , light, chlorophyll and nutrients, and the development of a new locally based nutrient lo ading model. This process has given us a comprehensive understanding of the relationships between nutrient loading and water quality responses in the Bay. Specifically, we recommend that the EPA consider adopting the downstream protective loads that will be established by the SBEP for the estuarine and coastal waters rule. The SBEP will present draft criteria to the FDEP and EPA by June, 2010. Thank you for your advanced consideration of this information rega rding numeric nutrient criteria developed by the SBEP in the wate r quality standards rule making process.

References
FDEP. 2005. Nutrient TMDL for Roberts Ba y (WBID 1968D). Florid a Department of Environmental Protection, Tallahassee, FL. 55 pp Greening, H. and A. Janicki. 2006. Toward revers al of eutrophic conditio ns in a subtropical estuary: water quality and seagrass response to nitrogen loading reductions in Tampa Bay, Florida, USA. Environmental Management Vol. 38, No. 2, pp. 163-178. Janicki, A.J. and D.L. Wade. 1996. Estimating Critical Nitrogen Loads for the Tampa Bay Estuary: An Empirically Based Approach to Setting Management Targets. Technical Publication #06-96 of the Tampa Bay Nationa l Estuary Program. Prepared by Coastal Environmental, Inc. Lowrey, S. 1992. Physical and chemical proper ties – Bay water and sediment quality. Pp. 4.1 – 4.20, In: (P.Roat, C. Ciccolella, H. Smith, and D. Tomasko, eds.). Sarasota Bay: Framework for Action. Sarasota Bay Nati onal Estuary Program, Sarasota, FL. PBS&J. 2009. Status and trends in pollutant load s and natural resource responses in Sarasota Bay. Final Report SBEP to the City of Sarasota. 15p. CCMP. 1995. Sarasota Bay: The Voyage to Paradise Reclaimed. The Comprehensive Conservation Management Plan for Sarasota Bay. Sarasota Bay National Estuary Program.
Serviss, G.M. and S. Sauers. 2003. Sarasota Ba y Juvenile Fisheries Habitat Assessment. Final Report to the Sarasota Ba y National Estuary Program. 212 p. SWFWMD. 2008. Seagrass distributi on from Tarpon Springs to Boca Grande. Final Report.

# Tomasko, D.A., C.A. Corbett, H.S. Greeni ng, G.E. Raulerson. 2005. Spatial and temporal variation in seagrass coverage in Southwest Florida: assessing the relative effects of anthropogenic nutrient load reductio ns and rainfall in four con tiguous estuaries. Mar. Poll. Bull . 50: 797-805.
Tomasko, D.A., M. Alderson and J. Leverone. 2009. Response of water quality and seagrass coverage to large-scale reductions in nitrogen lo ads to Sarasota Bay. Oral Presentation to the 20 th 

# Biennial Conference of the Coastal and Estuarine Research Fe deration. November 1-5, 2009. Portland, OR.

Other Relevant Literature Reviewed Dillon, K.S. and J.P. Chanton. 2008. Nitroge n stable isotopes of macrophytes assess stormwater nitrogen inputs to an urbanized estuary. Estuaries and Coasts . 31: 360-370. Johansson, J.O.R. 1991. Long-term trends of nitrogen loading, water quality and biological indicators in Hillsborough Bay, Florida. Pp. 157- 176. In: (Treat, S.F., and P.A. Clark, eds.). Proceedings, Tampa Bay Area Scien tific Information Symposium 2 . Southwest Florida Regional Planning Council, St. Petersburg, FL. 528 pp. National Research Council, 1993. Managing Wastewater in Coastal Urban Areas . National Academy Press, Washington, DC.
Tomasko, D.A., Dawes, C.J., and M.O. Hall. 1996. The effects of anthropogenic nutrient enrichment on turtle grass ( Thalassia testudinum ) in Sarasota Bay, Florida. Estuaries 19: 448-456.

# Appendix 2. Water Quality Sampling Programs

# Ambient Water Quality Sampling Programs in the SBEP Area Both Sarasota County and Manatee County collect water quality data within the SBEP area. The two monitoring programs are briefly described below. This Sarasota County ambient water quality monitoring prog ram was initiated in 1995. Sarasota Bay was divided into 12 segments, each with multiple randomly chosen sampling sites. The Sarasota County Ambient Wate r Quality Monitoring Network segmentation scheme is shown in Figure 1. All program sample locations are sampled once every year. Each site is re-sampled every year in the same month as the preceding years. This randomized, stratified monitori ng program characterizes o verall estuarine health by describing entire bay segments rather than isolated locations in each water body.

Figure 1. Sarasota County Ambient Water Quality Segments.



# Aqueous samples are taken from mid-depth fr om the entire coastal estuarine system in Sarasota County, including Sarasota Bay, Ro berts Bay (Sarasota), Little Sarasota Bay, Blackburn Bay, Lyons Bay, Dona Bay, Roberts Bay (Venice), Lemon Bay and the estuarine portion of the Myakka River.

# Dataloggers are deployed at the same stations defined by the sampling program. Datalogger site selection produces a balanced distribution of data from throughout the study area. Two dataloggers are deployed m onthly to measure temperature, salinity, dissolved oxygen concentra tion, percent oxygen concen tration, pH, and specific conductance at 15 minute intervals for at le ast one complete 24-hour period. Field meter readings are taken at top, middle and bottom depths.
The Manatee County Environmental Management Department (EMD) ambient water quality monitoring program for Manatee County's estuarine waters is the R egional A mbient M onitoring P rogram. RAMP began in November, 1995 and is the successor to EMD's old AWP station network that had operated since 1988. RAMP evolved from a series of Tampa Bay Estuary Program sponsored workshops on the methods, vari ables and field techniques of estuarine water quality monitoring to improve data compatib ility among the water quality monitoring programs of the different jurisdictions. All RAMP implementations use the same sampling design and include the sa me set of core measurements. The RAMP concept has been endorsed by the Tampa Ba y, Sarasota Bay, and Charlotte Harbor National Estuary Programs. The Manatee County RAMP program divides the Co unty's estuarine area into two segments of 24, 3.56km 2 

# hexagonal sampling areas each. The south segment includes Palma Sola Bay, and Sarasota Bay north of the county line, both of which are within the SBEP area. Sampling points were randomly located within e ach hexagon at the start of the program. A hexagonal sampling area was included in th e program if the randomly generated sampling point was at least 4ft deep by the na utical chart and verified during program reconnaissance. The statistical basis of the RAMP design allows for the addition of preselected stations if there was no overriding physical reason for th e station's geographic placement at a particular poin t. One-third of the sampling points in each segment, eight points, are sampled monthly. All sampling poi nts in a segment are visited within each calendar quarter. In bay segments where both Sarasota and Manatee counties sample, averaged data from both programs are presented. Also, based on discussions with representatives of the sampling programs, it was decided to exclude data from segment 12 from the analysis. Segment 12 is in Big Sarasota Pass and li kely reflects Gulf of Mexico water quality characteristics as much or more so than ba y water characteristics, especially during flood tide sampling events. Maps of the sampling locations in Sarasota Ba y are provided below in Figure 2. It should be noted that the rotating sa mpling schedule for Sarasota County’s sites are regular (monthly), and are shown for each month. Manatee County’s sampling rotation is not as regular so symbols representing each sampling grid cell are illustrated.

# Figure 2a. Sarasota Bay Sampling Sites - January

Figure 2b. Sarasota Bay Sampling Sites - February Figure 2c. Sarasota Bay Sampling Sites – March.

Figure 2d. Sarasota Bay Sampling Sites – April.

# Figure 2e. Sarasota Bay Sampling Sites - May

Figure 2f. Sarasota Bay Sampling Sites - June Figure 2g. Sarasota Bay Sampling Sites – July.

Figure 2h. Sarasota Bay Sampling Sites - August

# Figure 2i. Sarasota Bay sampling sites – September.

Figure 2j. Sarasota Bay sampling sites – October. Figure 2k. Sarasota Bay sampling sites - November

Figure 2l. Sarasota Bay sampling sites – December.

# Appendix 3. Water Quality Trend TestsChlorophyll a (ug/l) Palma Sola Bay Trends Appendix - Display 1 X Monthly Data Time Series X Chlorophyll a X Not Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Chlorophyll a

(ug/l) Palma Sola Bay Trends Appendix - Display 2 X Monthly Data Time Series X Chlorophyll a X Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40

98 99 00 01 02 03 04 05 06 07 08 09 10

Chlorophyll a (ug/l) Palma Sola Bay Trends Appendix - Display 3 X X Seasonal Univariate Statistics X Chlorophyll a X X X

0 5 10 15 20 25 30 35 40

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Palma Sola Bay Trends Appendix - Display 4

X Autocorrelation Statistics for Chlorophyll a

X Unadjusted for Seasonal Medians

X Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.063 0.126 -0.126 1 0.463 0.109 0.218 -0.218 2 0.296 0.117 0.233 -0.233 3 0.180 0.120 0.239 -0.239 4 0.008 0.121 0.241 -0.241 5 -0.012 0.121 0.241 -0.241 6 0.005 0.121 0.241 -0.241 7 -0.165 0.121 0.241 -0.241 8 -0.062 0.122 0.243 -0.243 9 -0.029 0.122 0.243 -0.243 10 0.104 0.122 0.243 -0.243 11 0.165 0.122 0.244 -0.244 12 0.278 0.123 0.246 -0.246 13 0.141 0.125 0.251 -0.251 14 -0.002 0.126 0.252 -0.252 15 -0.007 0.126 0.252 -0.252

Correlation Palma Sola Bay Trends Appendix - Display 5

X Correlogram for Chlorophyll a

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Chlorophyll a 01234 5 6 7 8 9 10 11 12 13 14 15 Palma Sola Bay Trends Appendix - Display 6 X Seasonal Kendall Tau Trend Test Statistics Chlorophyll a X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.207 .004 0.079 -0.3Palma Sola Bay Trends Appendix - Display 7 X Seasonal Kendall Tau Trend Test Statistics Chlorophyll a X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.20671 .00430537 0.079404 -0.3 Adjusted (ug/l) Palma Sola Bay Trends Appendix - Display 8 X Time Series Plot of Data Adjusted for Season and Detrended Chlorophyll a X

Zero Reference Line Shown -10

0 10 20 30

98 99 00 01 02 03 04 05 06 07 08 09 10

Palma Sola Bay Trends Appendix - Display 9 X Autocorrelation Statistics for Chlorophyll a

X Adjusted for Seasonal Median and Detrended Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.063 0.126 -0.126 1 0.302 0.109 0.218 -0.218 2 0.185 0.112 0.225 -0.225 3 0.195 0.114 0.227 -0.227 4 0.100 0.115 0.230 -0.230 5 0.177 0.115 0.231 -0.231 6 0.148 0.116 0.233 -0.233 7 -0.016 0.117 0.234 -0.234 8 0.088 0.117 0.234 -0.234 9 -0.046 0.117 0.235 -0.235 10 -0.036 0.117 0.235 -0.235 11 0.004 0.117 0.235 -0.235 12 -0.029 0.117 0.235 -0.235 13 -0.064 0.117 0.235 -0.235 Palma Sola Bay Trends Appendix - Display 9 X Autocorrelation Statistics for Chlorophyll a X Adjusted for Seasonal Median and Detrended Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 14 -0.089 0.118 0.235 -0.235 15 -0.120 0.118 0.236 -0.236

Correlation Palma Sola Bay Trends Appendix - Display 10 X Correlogram for Chlorophyll a

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Chlorophyll a 01234 5 6 7 8 9 10 11 12 13 14 15Salinity (ppt) Palma Sola Bay Trends Appendix - Display 11 X Monthly Data Time Series X Salinity

X Not Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40 45

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Salinity (ppt) Palma Sola Bay Trends Appendix - Display 12 X Monthly Data Time Series X Salinity

X Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40 45

98 99 00 01 02 03 04 05 06 07 08 09 10

Salinity (ppt) Palma Sola Bay Trends Appendix - Display 13 X X Seasonal Univariate Statistics X Salinity

X X X

0 5 10 15 20 25 30 35 40 45

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Palma Sola Bay Trends Appendix - Display 14

X Autocorrelation Statistics for Salinity

X Unadjusted for Seasonal Medians

X Lagged Salinity Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.063 0.126 -0.126 1 0.633 0.109 0.218 -0.218 2 0.500 0.123 0.246 -0.246 3 0.453 0.131 0.261 -0.261 4 0.212 0.137 0.273 -0.273 5 0.093 0.138 0.276 -0.276 6 0.249 0.138 0.277 -0.277 7 0.169 0.140 0.280 -0.280 8 0.299 0.141 0.282 -0.282 9 0.396 0.143 0.287 -0.287 10 0.334 0.148 0.295 -0.295 11 0.359 0.151 0.301 -0.301 12 0.365 0.154 0.308 -0.308 13 0.193 0.157 0.315 -0.315 14 0.170 0.158 0.317 -0.317 15 0.064 0.159 0.318 -0.318

Correlation Palma Sola Bay Trends Appendix - Display 15

X Correlogram for Salinity

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Salinity 01234 5 6 7 8 9 10 11 12 13 14 15 Palma Sola Bay Trends Appendix - Display 16 X Seasonal Kendall Tau Trend Test Statistics Salinity

X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.276 0 0.052 0.267Palma Sola Bay Trends Appendix - Display 17 X Seasonal Kendall Tau Trend Test Statistics Salinity

X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.27563 .000101447 0.051933 0.26667 Adjusted (ppt) Palma Sola Bay Trends Appendix - Display 18 X Time Series Plot of Data Adjusted for Season and Detrended Salinity

X

Zero Reference Line Shown -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7

98 99 00 01 02 03 04 05 06 07 08 09 10

Palma Sola Bay Trends Appendix - Display 19 X Autocorrelation Statistics for Salinity

X Adjusted for Seasonal Median and Detrended Lagged Salinity Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.063 0.126 -0.126 1 0.549 0.109 0.218 -0.218 2 0.410 0.120 0.239 -0.239 3 0.361 0.125 0.250 -0.250 4 0.173 0.129 0.258 -0.258 5 0.050 0.130 0.260 -0.260 6 0.171 0.130 0.260 -0.260 7 0.181 0.131 0.262 -0.262 8 0.296 0.132 0.264 -0.264 9 0.360 0.135 0.269 -0.269 10 0.250 0.138 0.277 -0.277 11 0.244 0.140 0.280 -0.280 12 0.227 0.142 0.284 -0.284 13 0.103 0.143 0.286 -0.286 14 0.041 0.144 0.287 -0.287 15 -0.055 0.144 0.287 -0.287 Correlation Palma Sola Bay Trends Appendix - Display 20 X Correlogram for Salinity

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Salinity 01234 5 6 7 8 9 10 11 12 13 14 15Total Nitrogen (mg/L) Palma Sola Bay Trends Appendix - Display 21 X Monthly Data Time Series X Total Nitrogen X Not Adjusted for Seasonal Medians X

0.0 0.5 1.0 1.5 2.0 2.5 3.0

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Total Nitrogen (mg/L) Palma Sola Bay Trends Appendix - Display 22 X Monthly Data Time Series X Total Nitrogen X Adjusted for Seasonal Medians X

0.0 0.5 1.0 1.5 2.0 2.5 3.0

98 99 00 01 02 03 04 05 06 07 08 09 10

Total Nitrogen (mg/L) Palma Sola Bay Trends Appendix - Display 23 X X Seasonal Univariate Statistics X Total Nitrogen X X X

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Palma Sola Bay Trends Appendix - Display 24

X Autocorrelation Statistics for Total Nitrogen

X Unadjusted for Seasonal Medians

X Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.063 0.126 -0.126 1 0.430 0.109 0.218 -0.218 2 0.213 0.116 0.231 -0.231 3 0.161 0.117 0.234 -0.234 4 -0.064 0.118 0.236 -0.236 5 -0.047 0.118 0.236 -0.236 6 0.094 0.118 0.237 -0.237 7 0.166 0.119 0.237 -0.237 8 0.020 0.119 0.239 -0.239 9 0.081 0.119 0.239 -0.239 10 0.173 0.120 0.239 -0.239 11 0.011 0.121 0.241 -0.241 12 -0.022 0.121 0.241 -0.241 13 0.051 0.121 0.241 -0.241 14 -0.044 0.121 0.242 -0.242 15 -0.024 0.121 0.242 -0.242

Correlation Palma Sola Bay Trends Appendix - Display 25

X Correlogram for Total Nitrogen

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Nitrogen 01234 5 6 7 8 9 10 11 12 13 14 15 Palma Sola Bay Trends Appendix - Display 26 X Seasonal Kendall Tau Trend Test Statistics Total Nitrogen X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.083 0.303 0.415 -.009Palma Sola Bay Trends Appendix - Display 27 X Seasonal Kendall Tau Trend Test Statistics Total Nitrogen X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.083141 0.30273 0.41546 -.00875 Adjusted (mg/L) Palma Sola Bay Trends Appendix - Display 28 X Time Series Plot of Data Adjusted for Season and Detrended Total Nitrogen X

Zero Reference Line Shown -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2

98 99 00 01 02 03 04 05 06 07 08 09 10

Palma Sola Bay Trends Appendix - Display 29 X Autocorrelation Statistics for Total Nitrogen

X Adjusted for Seasonal Median and Detrended Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.063 0.126 -0.126 1 0.387 0.109 0.218 -0.218 2 0.195 0.114 0.229 -0.229 3 0.197 0.116 0.231 -0.231 4 -0.065 0.117 0.234 -0.234 5 -0.042 0.117 0.234 -0.234 6 0.114 0.117 0.235 -0.235 7 0.167 0.118 0.235 -0.235 8 0.088 0.119 0.237 -0.237 9 0.068 0.119 0.238 -0.238 10 0.135 0.119 0.238 -0.238 11 -0.128 0.120 0.239 -0.239 12 -0.096 0.120 0.240 -0.240 13 -0.096 0.121 0.241 -0.241 Palma Sola Bay Trends Appendix - Display 29 X Autocorrelation Statistics for Total Nitrogen

X Adjusted for Seasonal Median and Detrended Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 14 -0.093 0.121 0.242 -0.242 15 -0.078 0.121 0.242 -0.242

Correlation Palma Sola Bay Trends Appendix - Display 30 X Correlogram for Total Nitrogen

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Nitrogen 01234 5 6 7 8 9 10 11 12 13 14 15Total Phosphorous (mg/L) Palma Sola Bay Trends Appendix - Display 31 X Monthly Data Time Series X Total Phosphorous X Not Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Total Phosphorous (mg/L) Palma Sola Bay Trends Appendix - Display 32 X Monthly Data Time Series X Total Phosphorous X Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

98 99 00 01 02 03 04 05 06 07 08 09 10

Total Phosphorous (mg/L) Palma Sola Bay Trends Appendix - Display 33 X X Seasonal Univariate Statistics X Total Phosphorous X X X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Palma Sola Bay Trends Appendix - Display 34

X Autocorrelation Statistics for Total Phosphorous

X Unadjusted for Seasonal Medians

X Lagged Total Phosphorous Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.063 0.126 -0.126 1 0.379 0.109 0.218 -0.218 2 0.320 0.114 0.228 -0.228 3 0.272 0.118 0.235 -0.235 4 -0.036 0.120 0.240 -0.240 5 -0.066 0.120 0.240 -0.240 6 0.029 0.120 0.241 -0.241 7 0.016 0.120 0.241 -0.241 8 -0.099 0.120 0.241 -0.241 9 -0.069 0.121 0.241 -0.241 10 0.056 0.121 0.242 -0.242 11 -0.103 0.121 0.242 -0.242 12 -0.096 0.121 0.243 -0.243 13 0.043 0.122 0.243 -0.243 14 0.121 0.122 0.243 -0.243 15 -0.055 0.122 0.244 -0.244

Correlation Palma Sola Bay Trends Appendix - Display 35

X Correlogram for Total Phosphorous

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Phosphorous 01234 5 6 7 8 9 10 11 12 13 14 15 Palma Sola Bay Trends Appendix - Display 36 X Seasonal Kendall Tau Trend Test Statistics Total Phosphorous X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.097 0.182 0.268 -.001Palma Sola Bay Trends Appendix - Display 37 X Seasonal Kendall Tau Trend Test Statistics Total Phosphorous X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.097196 0.18177 0.26846 -.00125 Adjusted (mg/L) Palma Sola Bay Trends Appendix - Display 38 X Time Series Plot of Data Adjusted for Season and Detrended Total Phosphorous X

Zero Reference Line Shown -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2

98 99 00 01 02 03 04 05 06 07 08 09 10

Palma Sola Bay Trends Appendix - Display 39 X Autocorrelation Statistics for Total Phosphorous

X Adjusted for Seasonal Median and Detrended Lagged Total Phosphorous Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.063 0.126 -0.126 1 0.417 0.109 0.218 -0.218 2 0.323 0.115 0.231 -0.231 3 0.261 0.119 0.238 -0.238 4 -0.025 0.121 0.242 -0.242 5 -0.096 0.121 0.242 -0.242 6 0.040 0.121 0.243 -0.243 7 -0.039 0.121 0.243 -0.243 8 -0.075 0.121 0.243 -0.243 9 -0.064 0.122 0.243 -0.243 10 0.050 0.122 0.244 -0.244 11 -0.084 0.122 0.244 -0.244 12 -0.148 0.122 0.244 -0.244 13 0.094 0.123 0.246 -0.246 14 0.123 0.123 0.246 -0.246 15 -0.042 0.124 0.247 -0.247 Correlation Palma Sola Bay Trends Appendix - Display 40 X Correlogram for Total Phosphorous

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Phosphorous 01234 5 6 7 8 9 10 11 12 13 14 15Chlorophyll a (ug/l) Sarasota Bay Trends Appendix - Display 1 X Monthly Data Time Series X Chlorophyll a X Not Adjusted for Seasonal Medians X

0 2 4 6 8 10 12 14 16

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Chlorophyll a

(ug/l) Sarasota Bay Trends Appendix - Display 2 X Monthly Data Time Series X Chlorophyll a X Adjusted for Seasonal Medians X

0 2 4 6 8 10 12 14 16

98 99 00 01 02 03 04 05 06 07 08 09 10

Chlorophyll a (ug/l) Sarasota Bay Trends Appendix - Display 3 X X Seasonal Univariate Statistics X Chlorophyll a X X X

0 2 4 6 8 10 12 14 16

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Sarasota Bay Trends Appendix - Display 4

X Autocorrelation Statistics for Chlorophyll a

X Unadjusted for Seasonal Medians

X Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.431 0.107 0.213 -0.213 2 0.226 0.113 0.226 -0.226 3 0.011 0.115 0.229 -0.229 4 -0.204 0.115 0.229 -0.229 5 -0.336 0.116 0.232 -0.232 6 -0.338 0.120 0.239 -0.239 7 -0.268 0.123 0.247 -0.247 8 -0.215 0.125 0.251 -0.251 9 -0.018 0.127 0.254 -0.254 10 0.174 0.127 0.254 -0.254 11 0.320 0.128 0.256 -0.256 12 0.414 0.131 0.262 -0.262 13 0.384 0.136 0.271 -0.271 14 0.215 0.140 0.279 -0.279 15 0.062 0.141 0.282 -0.282

Correlation Sarasota Bay Trends Appendix - Display 5

X Correlogram for Chlorophyll a

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Chlorophyll a 01234 5 6 7 8 9 10 11 12 13 14 15 Sarasota Bay Trends Appendix - Display 6 X Seasonal Kendall Tau Trend Test Statistics Chlorophyll a X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.127 0.03 0.152 -0.077Sarasota Bay Trends Appendix - Display 7 X Seasonal Kendall Tau Trend Test Statistics Chlorophyll a X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.12685 0.030380 0.15161 -0.07675 Adjusted (ug/l) Sarasota Bay Trends Appendix - Display 8 X Time Series Plot of Data Adjusted for Season and Detrended Chlorophyll a X

Zero Reference Line Shown -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11

98 99 00 01 02 03 04 05 06 07 08 09 10

Sarasota Bay Trends Appendix - Display 9 X Autocorrelation Statistics for Chlorophyll a

X Adjusted for Seasonal Median and Detrended Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.135 0.107 0.213 -0.213 2 0.034 0.107 0.214 -0.214 3 0.030 0.107 0.215 -0.215 4 0.004 0.107 0.215 -0.215 5 -0.030 0.107 0.215 -0.215 6 0.035 0.107 0.215 -0.215 7 0.090 0.107 0.215 -0.215 8 0.005 0.108 0.215 -0.215 9 0.043 0.108 0.215 -0.215 10 0.011 0.108 0.215 -0.215 11 -0.050 0.108 0.216 -0.216 12 -0.075 0.108 0.216 -0.216 13 0.002 0.108 0.216 -0.216 Sarasota Bay Trends Appendix - Display 9 X Autocorrelation Statistics for Chlorophyll a X Adjusted for Seasonal Median and Detrended Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 14 -0.030 0.108 0.216 -0.216 15 0.064 0.108 0.216 -0.216

Correlation Sarasota Bay Trends Appendix - Display 10 X Correlogram for Chlorophyll a

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Chlorophyll a 01234 5 6 7 8 9 10 11 12 13 14 15Salinity (ppt) Sarasota Bay Trends Appendix - Display 11 X Monthly Data Time Series X Salinity

X Not Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40 45

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Salinity (ppt) Sarasota Bay Trends Appendix - Display 12 X Monthly Data Time Series X Salinity

X Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40 45

98 99 00 01 02 03 04 05 06 07 08 09 10

Salinity (ppt) Sarasota Bay Trends Appendix - Display 13 X X Seasonal Univariate Statistics X Salinity

X X X

0 5 10 15 20 25 30 35 40 45

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Sarasota Bay Trends Appendix - Display 14

X Autocorrelation Statistics for Salinity

X Unadjusted for Seasonal Medians

X Lagged Salinity Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.624 0.107 0.213 -0.213 2 0.560 0.120 0.239 -0.239 3 0.483 0.129 0.258 -0.258 4 0.429 0.136 0.272 -0.272 5 0.422 0.141 0.282 -0.282 6 0.424 0.146 0.291 -0.291 7 0.436 0.150 0.300 -0.300 8 0.419 0.155 0.310 -0.310 9 0.449 0.159 0.318 -0.318 10 0.418 0.164 0.328 -0.328 11 0.467 0.168 0.336 -0.336 12 0.547 0.173 0.345 -0.345 13 0.432 0.179 0.358 -0.358 14 0.380 0.183 0.366 -0.366 15 0.274 0.186 0.372 -0.372

Correlation Sarasota Bay Trends Appendix - Display 15

X Correlogram for Salinity

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Salinity 01234 5 6 7 8 9 10 11 12 13 14 15 Sarasota Bay Trends Appendix - Display 16 X Seasonal Kendall Tau Trend Test Statistics Salinity

X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.421 0 .005 0.322Sarasota Bay Trends Appendix - Display 17 X Seasonal Kendall Tau Trend Test Statistics Salinity

X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.42130 0 .00498998 0.32167 Adjusted (ppt) Sarasota Bay Trends Appendix - Display 18 X Time Series Plot of Data Adjusted for Season and Detrended Salinity

X

Zero Reference Line Shown -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0

98 99 00 01 02 03 04 05 06 07 08 09 10

Sarasota Bay Trends Appendix - Display 19 X Autocorrelation Statistics for Salinity

X Adjusted for Seasonal Median and Detrended Lagged Salinity Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.495 0.107 0.213 -0.213 2 0.427 0.115 0.230 -0.230 3 0.359 0.121 0.242 -0.242 4 0.306 0.125 0.250 -0.250 5 0.265 0.128 0.255 -0.255 6 0.273 0.130 0.259 -0.259 7 0.308 0.132 0.264 -0.264 8 0.302 0.135 0.269 -0.269 9 0.342 0.137 0.274 -0.274 10 0.262 0.140 0.281 -0.281 11 0.307 0.142 0.284 -0.284 12 0.306 0.145 0.289 -0.289 13 0.213 0.147 0.294 -0.294 14 0.248 0.148 0.296 -0.296 15 0.132 0.150 0.300 -0.300 Correlation Sarasota Bay Trends Appendix - Display 20 X Correlogram for Salinity

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Salinity 01234 5 6 7 8 9 10 11 12 13 14 15Total Nitrogen (mg/L) Sarasota Bay Trends Appendix - Display 21 X Monthly Data Time Series X Total Nitrogen X Not Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Total Nitrogen (mg/L) Sarasota Bay Trends Appendix - Display 22 X Monthly Data Time Series X Total Nitrogen X Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

98 99 00 01 02 03 04 05 06 07 08 09 10

Total Nitrogen (mg/L) Sarasota Bay Trends Appendix - Display 23 X X Seasonal Univariate Statistics X Total Nitrogen X X X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Sarasota Bay Trends Appendix - Display 24

X Autocorrelation Statistics for Total Nitrogen

X Unadjusted for Seasonal Medians

X Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.482 0.107 0.213 -0.213 2 0.404 0.115 0.229 -0.229 3 0.235 0.120 0.240 -0.240 4 0.092 0.122 0.243 -0.243 5 0.149 0.122 0.244 -0.244 6 0.069 0.123 0.245 -0.245 7 0.134 0.123 0.245 -0.245 8 0.115 0.123 0.246 -0.246 9 0.248 0.124 0.247 -0.247 10 0.229 0.125 0.251 -0.251 11 0.250 0.127 0.254 -0.254 12 0.187 0.129 0.258 -0.258 13 0.234 0.130 0.260 -0.260 14 0.213 0.132 0.263 -0.263 15 0.134 0.133 0.266 -0.266

Correlation Sarasota Bay Trends Appendix - Display 25

X Correlogram for Total Nitrogen

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Nitrogen 01234 5 6 7 8 9 10 11 12 13 14 15 Sarasota Bay Trends Appendix - Display 26 X Seasonal Kendall Tau Trend Test Statistics Total Nitrogen X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.193 .001 0.09 -.009Sarasota Bay Trends Appendix - Display 27 X Seasonal Kendall Tau Trend Test Statistics Total Nitrogen X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.1926 .00104595 0.090172 -.00875 Adjusted (mg/L) Sarasota Bay Trends Appendix - Display 28 X Time Series Plot of Data Adjusted for Season and Detrended Total Nitrogen X

Zero Reference Line Shown -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

98 99 00 01 02 03 04 05 06 07 08 09 10

Sarasota Bay Trends Appendix - Display 29 X Autocorrelation Statistics for Total Nitrogen

X Adjusted for Seasonal Median and Detrended Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.344 0.107 0.213 -0.213 2 0.322 0.111 0.221 -0.221 3 0.208 0.114 0.228 -0.228 4 0.145 0.116 0.231 -0.231 5 0.253 0.116 0.233 -0.233 6 0.159 0.118 0.237 -0.237 7 0.217 0.119 0.238 -0.238 8 0.160 0.121 0.241 -0.241 9 0.207 0.122 0.243 -0.243 10 0.089 0.123 0.246 -0.246 11 0.060 0.123 0.246 -0.246 12 -0.011 0.123 0.246 -0.246 13 0.044 0.123 0.246 -0.246 Sarasota Bay Trends Appendix - Display 29 X Autocorrelation Statistics for Total Nitrogen X Adjusted for Seasonal Median and Detrended Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 14 0.103 0.123 0.247 -0.247 15 0.072 0.124 0.247 -0.247

Correlation Sarasota Bay Trends Appendix - Display 30 X Correlogram for Total Nitrogen

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Nitrogen 01234 5 6 7 8 9 10 11 12 13 14 15Total Phosphorous (mg/L) Sarasota Bay Trends Appendix - Display 31 X Monthly Data Time Series X Total Phosphorous X Not Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Total Phosphorous (mg/L) Sarasota Bay Trends Appendix - Display 32 X Monthly Data Time Series X Total Phosphorous X Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

98 99 00 01 02 03 04 05 06 07 08 09 10

Total Phosphorous (mg/L) Sarasota Bay Trends Appendix - Display 33 X X Seasonal Univariate Statistics X Total Phosphorous X X X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Sarasota Bay Trends Appendix - Display 34

X Autocorrelation Statistics for Total Phosphorous

X Unadjusted for Seasonal Medians

X Lagged Total Phosphorous Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.261 0.107 0.213 -0.213 2 0.162 0.109 0.218 -0.218 3 0.285 0.110 0.220 -0.220 4 0.184 0.113 0.225 -0.225 5 0.096 0.114 0.228 -0.228 6 0.084 0.114 0.228 -0.228 7 0.083 0.114 0.229 -0.229 8 0.028 0.115 0.229 -0.229 9 0.017 0.115 0.229 -0.229 10 0.197 0.115 0.229 -0.229 11 0.083 0.116 0.232 -0.232 12 0.100 0.116 0.232 -0.232 13 0.109 0.116 0.233 -0.233 14 0.060 0.117 0.234 -0.234 15 0.094 0.117 0.234 -0.234

Correlation Sarasota Bay Trends Appendix - Display 35

X Correlogram for Total Phosphorous

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Phosphorous 01234 5 6 7 8 9 10 11 12 13 14 15 Sarasota Bay Trends Appendix - Display 36 X Seasonal Kendall Tau Trend Test Statistics Total Phosphorous X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.122 0.035 0.382 -.002Sarasota Bay Trends Appendix - Display 37 X Seasonal Kendall Tau Trend Test Statistics Total Phosphorous X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.12222 0.035065 0.38163 -.00166667 Adjusted (mg/L) Sarasota Bay Trends Appendix - Display 38 X Time Series Plot of Data Adjusted for Season and Detrended Total Phosphorous X

Zero Reference Line Shown -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

98 99 00 01 02 03 04 05 06 07 08 09 10

Sarasota Bay Trends Appendix - Display 39 X Autocorrelation Statistics for Total Phosphorous

X Adjusted for Seasonal Median and Detrended Lagged Total Phosphorous Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.244 0.107 0.213 -0.213 2 0.154 0.109 0.217 -0.217 3 0.274 0.110 0.219 -0.219 4 0.214 0.112 0.224 -0.224 5 0.132 0.114 0.227 -0.227 6 0.128 0.114 0.228 -0.228 7 0.117 0.115 0.229 -0.229 8 0.057 0.115 0.230 -0.230 9 -0.008 0.115 0.231 -0.231 10 0.196 0.115 0.231 -0.231 11 0.071 0.117 0.233 -0.233 12 0.074 0.117 0.233 -0.233 13 0.102 0.117 0.234 -0.234 14 0.055 0.117 0.234 -0.234 15 0.084 0.117 0.235 -0.235 Correlation Sarasota Bay Trends Appendix - Display 40 X Correlogram for Total Phosphorous

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Phosphorous 01234 5 6 7 8 9 10 11 12 13 14 15Chlorophyll a (ug/l) Roberts Bay Trends Appendix - Display 1 X Monthly Data Time Series X Chlorophyll a X Not Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Chlorophyll a

(ug/l) Roberts Bay Trends Appendix - Display 2 X Monthly Data Time Series X Chlorophyll a X Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40

98 99 00 01 02 03 04 05 06 07 08 09 10

Chlorophyll a (ug/l) Roberts Bay Trends Appendix - Display 3 X X Seasonal Univariate Statistics X Chlorophyll a X X X

0 5 10 15 20 25 30 35 40

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Roberts Bay Trends Appendix - Display 4

X Autocorrelation Statistics for Chlorophyll a

X Unadjusted for Seasonal Medians

X Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.455 0.107 0.213 -0.213 2 0.218 0.114 0.227 -0.227 3 -0.082 0.115 0.231 -0.231 4 -0.179 0.116 0.231 -0.231 5 -0.249 0.117 0.233 -0.233 6 -0.285 0.119 0.237 -0.237 7 -0.262 0.121 0.242 -0.242 8 -0.229 0.123 0.246 -0.246 9 -0.093 0.125 0.250 -0.250 10 0.132 0.125 0.250 -0.250 11 0.258 0.126 0.251 -0.251 12 0.367 0.128 0.255 -0.255 13 0.337 0.132 0.263 -0.263 14 0.108 0.135 0.270 -0.270 15 -0.042 0.135 0.270 -0.270

Correlation Roberts Bay Trends Appendix - Display 5

X Correlogram for Chlorophyll a

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Chlorophyll a 01234 5 6 7 8 9 10 11 12 13 14 15 Roberts Bay Trends Appendix - Display 6 X Seasonal Kendall Tau Trend Test Statistics Chlorophyll a X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.104 0.111 0.285 -0.132Roberts Bay Trends Appendix - Display 7 X Seasonal Kendall Tau Trend Test Statistics Chlorophyll a X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.10390 0.11082 0.28539 -0.13214 Adjusted (ug/l) Roberts Bay Trends Appendix - Display 8 X Time Series Plot of Data Adjusted for Season and Detrended Chlorophyll a X

Zero Reference Line Shown -20 -10

0 10 20 30 40

98 99 00 01 02 03 04 05 06 07 08 09 10

Roberts Bay Trends Appendix - Display 9 X Autocorrelation Statistics for Chlorophyll a

X Adjusted for Seasonal Median and Detrended Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.281 0.107 0.213 -0.213 2 0.058 0.109 0.219 -0.219 3 -0.092 0.109 0.219 -0.219 4 -0.006 0.110 0.220 -0.220 5 0.003 0.110 0.220 -0.220 6 -0.012 0.110 0.220 -0.220 7 -0.012 0.110 0.220 -0.220 8 -0.090 0.110 0.220 -0.220 9 -0.037 0.110 0.220 -0.220 10 -0.019 0.110 0.220 -0.220 11 -0.068 0.110 0.220 -0.220 12 -0.052 0.110 0.221 -0.221 13 0.032 0.110 0.221 -0.221 Roberts Bay Trends Appendix - Display 9 X Autocorrelation Statistics for Chlorophyll a X Adjusted for Seasonal Median and Detrended Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 14 -0.075 0.110 0.221 -0.221 15 -0.021 0.111 0.221 -0.221

Correlation Roberts Bay Trends Appendix - Display 10 X Correlogram for Chlorophyll a

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Chlorophyll a 01234 5 6 7 8 9 10 11 12 13 14 15Salinity (ppt) Roberts Bay Trends Appendix - Display 11 X Monthly Data Time Series X Salinity

X Not Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40 45

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Salinity (ppt) Roberts Bay Trends Appendix - Display 12 X Monthly Data Time Series X Salinity

X Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40 45

98 99 00 01 02 03 04 05 06 07 08 09 10

Salinity (ppt) Roberts Bay Trends Appendix - Display 13 X X Seasonal Univariate Statistics X Salinity

X X X

0 5 10 15 20 25 30 35 40 45

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Roberts Bay Trends Appendix - Display 14

X Autocorrelation Statistics for Salinity

X Unadjusted for Seasonal Medians

X Lagged Salinity Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.496 0.107 0.213 -0.213 2 0.177 0.115 0.230 -0.230 3 -0.001 0.116 0.232 -0.232 4 -0.045 0.116 0.232 -0.232 5 0.020 0.116 0.232 -0.232 6 -0.001 0.116 0.232 -0.232 7 -0.017 0.116 0.232 -0.232 8 -0.014 0.116 0.232 -0.232 9 -0.109 0.116 0.232 -0.232 10 0.018 0.117 0.233 -0.233 11 0.189 0.117 0.233 -0.233 12 0.310 0.118 0.235 -0.235 13 0.185 0.121 0.241 -0.241 14 -0.004 0.122 0.244 -0.244 15 -0.074 0.122 0.244 -0.244

Correlation Roberts Bay Trends Appendix - Display 15

X Correlogram for Salinity

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Salinity 01234 5 6 7 8 9 10 11 12 13 14 15 Roberts Bay Trends Appendix - Display 16 X Seasonal Kendall Tau Trend Test Statistics Salinity

X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.202 .002 0.14 0.192Roberts Bay Trends Appendix - Display 17 X Seasonal Kendall Tau Trend Test Statistics Salinity

X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.20187 .00201845 0.13981 0.19214 Adjusted (ppt) Roberts Bay Trends Appendix - Display 18 X Time Series Plot of Data Adjusted for Season and Detrended Salinity

X

Zero Reference Line Shown -30 -20 -10

0 10

98 99 00 01 02 03 04 05 06 07 08 09 10

Roberts Bay Trends Appendix - Display 19 X Autocorrelation Statistics for Salinity

X Adjusted for Seasonal Median and Detrended Lagged Salinity Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.439 0.107 0.213 -0.213 2 0.248 0.113 0.227 -0.227 3 0.153 0.115 0.231 -0.231 4 0.065 0.116 0.232 -0.232 5 0.093 0.116 0.232 -0.232 6 0.071 0.116 0.233 -0.233 7 0.065 0.117 0.233 -0.233 8 0.140 0.117 0.234 -0.234 9 0.041 0.117 0.235 -0.235 10 0.048 0.117 0.235 -0.235 11 -0.005 0.118 0.235 -0.235 12 -0.029 0.118 0.235 -0.235 13 0.014 0.118 0.235 -0.235 14 0.023 0.118 0.235 -0.235 15 0.083 0.118 0.235 -0.235 Correlation Roberts Bay Trends Appendix - Display 20 X Correlogram for Salinity

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Salinity 01234 5 6 7 8 9 10 11 12 13 14 15Total Nitrogen (mg/L) Roberts Bay Trends Appendix - Display 21 X Monthly Data Time Series X Total Nitrogen X Not Adjusted for Seasonal Medians X

0.0 0.2 0.4 0.6 0.8 1.0 1.2

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Total Nitrogen (mg/L) Roberts Bay Trends Appendix - Display 22 X Monthly Data Time Series X Total Nitrogen X Adjusted for Seasonal Medians X

0.0 0.2 0.4 0.6 0.8 1.0 1.2

98 99 00 01 02 03 04 05 06 07 08 09 10

Total Nitrogen (mg/L) Roberts Bay Trends Appendix - Display 23 X X Seasonal Univariate Statistics X Total Nitrogen X X X

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Roberts Bay Trends Appendix - Display 24

X Autocorrelation Statistics for Total Nitrogen

X Unadjusted for Seasonal Medians

X Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.514 0.107 0.213 -0.213 2 0.245 0.116 0.231 -0.231 3 0.053 0.118 0.235 -0.235 4 -0.123 0.118 0.235 -0.235 5 -0.178 0.118 0.236 -0.236 6 -0.240 0.119 0.238 -0.238 7 -0.222 0.121 0.242 -0.242 8 -0.178 0.122 0.245 -0.245 9 -0.105 0.123 0.247 -0.247 10 0.092 0.124 0.248 -0.248 11 0.184 0.124 0.248 -0.248 12 0.286 0.125 0.250 -0.250 13 0.184 0.128 0.255 -0.255 14 0.117 0.129 0.257 -0.257 15 0.023 0.129 0.258 -0.258

Correlation Roberts Bay Trends Appendix - Display 25

X Correlogram for Total Nitrogen

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Nitrogen 01234 5 6 7 8 9 10 11 12 13 14 15 Roberts Bay Trends Appendix - Display 26 X Seasonal Kendall Tau Trend Test Statistics Total Nitrogen X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.044 0.504 0.527 .002Roberts Bay Trends Appendix - Display 27 X Seasonal Kendall Tau Trend Test Statistics Total Nitrogen X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.044156 0.50363 0.52685 .00154762 Adjusted (mg/L) Roberts Bay Trends Appendix - Display 28 X Time Series Plot of Data Adjusted for Season and Detrended Total Nitrogen X

Zero Reference Line Shown -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

98 99 00 01 02 03 04 05 06 07 08 09 10

Roberts Bay Trends Appendix - Display 29 X Autocorrelation Statistics for Total Nitrogen

X Adjusted for Seasonal Median and Detrended Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.442 0.107 0.213 -0.213 2 0.180 0.113 0.227 -0.227 3 0.104 0.114 0.229 -0.229 4 -0.002 0.115 0.230 -0.230 5 0.021 0.115 0.230 -0.230 6 -0.024 0.115 0.230 -0.230 7 -0.036 0.115 0.230 -0.230 8 -0.075 0.115 0.230 -0.230 9 -0.100 0.115 0.230 -0.230 10 -0.017 0.115 0.231 -0.231 11 -0.048 0.115 0.231 -0.231 12 -0.005 0.115 0.231 -0.231 13 -0.033 0.115 0.231 -0.231 Roberts Bay Trends Appendix - Display 29 X Autocorrelation Statistics for Total Nitrogen

X Adjusted for Seasonal Median and Detrended Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 14 0.018 0.115 0.231 -0.231 15 0.062 0.115 0.231 -0.231

Correlation Roberts Bay Trends Appendix - Display 30 X Correlogram for Total Nitrogen

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Nitrogen 01234 5 6 7 8 9 10 11 12 13 14 15Total Phosphorous (mg/L) Roberts Bay Trends Appendix - Display 31 X Monthly Data Time Series X Total Phosphorous X Not Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Total Phosphorous (mg/L) Roberts Bay Trends Appendix - Display 32 X Monthly Data Time Series X Total Phosphorous X Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5

98 99 00 01 02 03 04 05 06 07 08 09 10

Total Phosphorous (mg/L) Roberts Bay Trends Appendix - Display 33 X X Seasonal Univariate Statistics X Total Phosphorous X X X

0.0 0.1 0.2 0.3 0.4 0.5

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Roberts Bay Trends Appendix - Display 34

X Autocorrelation Statistics for Total Phosphorous

X Unadjusted for Seasonal Medians

X Lagged Total Phosphorous Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.518 0.107 0.213 -0.213 2 0.364 0.116 0.232 -0.232 3 0.368 0.120 0.240 -0.240 4 0.257 0.124 0.248 -0.248 5 0.108 0.126 0.252 -0.252 6 0.122 0.127 0.253 -0.253 7 0.088 0.127 0.254 -0.254 8 0.144 0.127 0.254 -0.254 9 0.146 0.128 0.256 -0.256 10 0.195 0.128 0.257 -0.257 11 0.240 0.130 0.259 -0.259 12 0.192 0.131 0.263 -0.263 13 0.187 0.132 0.265 -0.265 14 0.201 0.133 0.267 -0.267 15 0.145 0.134 0.269 -0.269

Correlation Roberts Bay Trends Appendix - Display 35

X Correlogram for Total Phosphorous

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Phosphorous 01234 5 6 7 8 9 10 11 12 13 14 15 Roberts Bay Trends Appendix - Display 36 X Seasonal Kendall Tau Trend Test Statistics Total Phosphorous X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.329 0 0.031 -.007Roberts Bay Trends Appendix - Display 37 X Seasonal Kendall Tau Trend Test Statistics Total Phosphorous X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.32857 .000000318 0.031076 -.00666667 Adjusted (mg/L) Roberts Bay Trends Appendix - Display 38 X Time Series Plot of Data Adjusted for Season and Detrended Total Phosphorous X

Zero Reference Line Shown -0.02 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.26 0.28 0.30 0.32 0.34 0.36

98 99 00 01 02 03 04 05 06 07 08 09 10

Roberts Bay Trends Appendix - Display 39 X Autocorrelation Statistics for Total Phosphorous

X Adjusted for Seasonal Median and Detrended Lagged Total Phosphorous Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.378 0.107 0.213 -0.213 2 0.218 0.112 0.223 -0.223 3 0.300 0.113 0.226 -0.226 4 0.216 0.116 0.232 -0.232 5 0.083 0.118 0.235 -0.235 6 0.090 0.118 0.236 -0.236 7 0.046 0.118 0.236 -0.236 8 0.050 0.118 0.236 -0.236 9 -0.016 0.118 0.237 -0.237 10 -0.026 0.118 0.237 -0.237 11 -0.028 0.118 0.237 -0.237 12 -0.144 0.118 0.237 -0.237 13 -0.112 0.119 0.238 -0.238 14 -0.018 0.119 0.239 -0.239 15 -0.010 0.119 0.239 -0.239 Correlation Roberts Bay Trends Appendix - Display 40 X Correlogram for Total Phosphorous

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Phosphorous 01234 5 6 7 8 9 10 11 12 13 14 15Chlorophyll a (ug/l) Little Sarasota Bay Trends Appendix - Display 1 X Monthly Data Time Series X Chlorophyll a X Not Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Chlorophyll a

(ug/l) Little Sarasota Bay Trends Appendix - Display 2 X Monthly Data Time Series X Chlorophyll a X Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40

98 99 00 01 02 03 04 05 06 07 08 09 10

Chlorophyll a (ug/l) Little Sarasota Bay Trends Appendix - Display 3 X X Seasonal Univariate Statistics X Chlorophyll a X X X

0 5 10 15 20 25 30 35 40

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Little Sarasota Bay Trends Appendix - Display 4

X Autocorrelation Statistics for Chlorophyll a

X Unadjusted for Seasonal Medians

X Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.503 0.107 0.213 -0.213 2 0.251 0.115 0.231 -0.231 3 -0.055 0.117 0.235 -0.235 4 -0.149 0.117 0.235 -0.235 5 -0.266 0.118 0.236 -0.236 6 -0.301 0.120 0.241 -0.241 7 -0.275 0.123 0.246 -0.246 8 -0.266 0.125 0.251 -0.251 9 -0.084 0.128 0.255 -0.255 10 0.109 0.128 0.256 -0.256 11 0.279 0.128 0.256 -0.256 12 0.357 0.130 0.261 -0.261 13 0.350 0.134 0.268 -0.268 14 0.180 0.138 0.275 -0.275 15 -0.034 0.138 0.277 -0.277

Correlation Little Sarasota Bay Trends Appendix - Display 5

X Correlogram for Chlorophyll a

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Chlorophyll a 01234 5 6 7 8 9 10 11 12 13 14 15 Little Sarasota Bay Trends Appendix - Display 6 X Seasonal Kendall Tau Trend Test Statistics Chlorophyll a X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.128 0.05 0.151 -0.115Little Sarasota Bay Trends Appendix - Display 7 X Seasonal Kendall Tau Trend Test Statistics Chlorophyll a X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.1278 0.050474 0.15075 -0.115 Adjusted (ug/l) Little Sarasota Bay Trends Appendix - Display 8 X Time Series Plot of Data Adjusted for Season and Detrended Chlorophyll a X

Zero Reference Line Shown -20 -10

0 10 20 30

98 99 00 01 02 03 04 05 06 07 08 09 10

Little Sarasota Bay Trends Appendix - Display 9 X Autocorrelation Statistics for Chlorophyll a

X Adjusted for Seasonal Median and Detrended Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.308 0.107 0.213 -0.213 2 0.114 0.110 0.220 -0.220 3 -0.077 0.110 0.221 -0.221 4 0.064 0.111 0.221 -0.221 5 -0.005 0.111 0.221 -0.221 6 -0.041 0.111 0.221 -0.221 7 -0.042 0.111 0.222 -0.222 8 -0.119 0.111 0.222 -0.222 9 -0.058 0.111 0.223 -0.223 10 -0.068 0.111 0.223 -0.223 11 -0.105 0.112 0.223 -0.223 12 -0.087 0.112 0.224 -0.224 13 0.040 0.112 0.224 -0.224 Little Sarasota Bay Trends Appendix - Display 9 X Autocorrelation Statistics for Chlorophyll a

X Adjusted for Seasonal Median and Detrended Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 14 0.023 0.112 0.225 -0.225 15 -0.021 0.112 0.225 -0.225

Correlation Little Sarasota Bay Trends Appendix - Display 10 X Correlogram for Chlorophyll a

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Chlorophyll a 01234 5 6 7 8 9 10 11 12 13 14 15Salinity (ppt) Little Sarasota Bay Trends Appendix - Display 11 X Monthly Data Time Series X Salinity

X Not Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40 45

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Salinity (ppt) Little Sarasota Bay Trends Appendix - Display 12 X Monthly Data Time Series X Salinity

X Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40 45

98 99 00 01 02 03 04 05 06 07 08 09 10

Salinity (ppt) Little Sarasota Bay Trends Appendix - Display 13 X X Seasonal Univariate Statistics X Salinity

X X X

0 5 10 15 20 25 30 35 40 45

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Little Sarasota Bay Trends Appendix - Display 14

X Autocorrelation Statistics for Salinity

X Unadjusted for Seasonal Medians

X Lagged Salinity Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.617 0.107 0.213 -0.213 2 0.293 0.119 0.239 -0.239 3 0.027 0.122 0.244 -0.244 4 -0.047 0.122 0.244 -0.244 5 -0.002 0.122 0.244 -0.244 6 0.017 0.122 0.244 -0.244 7 -0.012 0.122 0.244 -0.244 8 -0.044 0.122 0.244 -0.244 9 -0.092 0.122 0.244 -0.244 10 0.077 0.122 0.245 -0.245 11 0.225 0.123 0.245 -0.245 12 0.311 0.124 0.248 -0.248 13 0.150 0.127 0.254 -0.254 14 0.020 0.128 0.256 -0.256 15 -0.076 0.128 0.256 -0.256

Correlation Little Sarasota Bay Trends Appendix - Display 15

X Correlogram for Salinity

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Salinity 01234 5 6 7 8 9 10 11 12 13 14 15 Little Sarasota Bay Trends Appendix - Display 16 X Seasonal Kendall Tau Trend Test Statistics Salinity

X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.163 0.013 0.236 0.217Little Sarasota Bay Trends Appendix - Display 17 X Seasonal Kendall Tau Trend Test Statistics Salinity

X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.16310 0.012735 0.23566 0.21667 Adjusted (ppt) Little Sarasota Bay Trends Appendix - Display 18 X Time Series Plot of Data Adjusted for Season and Detrended Salinity

X

Zero Reference Line Shown -30 -20 -10

0 10

98 99 00 01 02 03 04 05 06 07 08 09 10

Little Sarasota Bay Trends Appendix - Display 19 X Autocorrelation Statistics for Salinity

X Adjusted for Seasonal Median and Detrended Lagged Salinity Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.596 0.107 0.213 -0.213 2 0.347 0.119 0.237 -0.237 3 0.163 0.122 0.245 -0.245 4 0.087 0.123 0.246 -0.246 5 0.078 0.123 0.247 -0.247 6 0.104 0.124 0.247 -0.247 7 0.086 0.124 0.248 -0.248 8 0.115 0.124 0.248 -0.248 9 0.035 0.125 0.249 -0.249 10 0.053 0.125 0.249 -0.249 11 0.029 0.125 0.249 -0.249 12 0.018 0.125 0.249 -0.249 13 -0.022 0.125 0.249 -0.249 14 0.030 0.125 0.249 -0.249 15 0.064 0.125 0.249 -0.249 Correlation Little Sarasota Bay Trends Appendix - Display 20 X Correlogram for Salinity

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Salinity 01234 5 6 7 8 9 10 11 12 13 14 15Total Nitrogen (mg/L) Little Sarasota Bay Trends Appendix - Display 21 X Monthly Data Time Series X Total Nitrogen X Not Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Total Nitrogen (mg/L) Little Sarasota Bay Trends Appendix - Display 22 X Monthly Data Time Series X Total Nitrogen X Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

98 99 00 01 02 03 04 05 06 07 08 09 10

Total Nitrogen (mg/L) Little Sarasota Bay Trends Appendix - Display 23 X X Seasonal Univariate Statistics X Total Nitrogen X X X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Little Sarasota Bay Trends Appendix - Display 24

X Autocorrelation Statistics for Total Nitrogen

X Unadjusted for Seasonal Medians

X Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.560 0.107 0.213 -0.213 2 0.274 0.117 0.234 -0.234 3 0.002 0.120 0.239 -0.239 4 -0.115 0.120 0.239 -0.239 5 -0.204 0.120 0.240 -0.240 6 -0.206 0.121 0.243 -0.243 7 -0.249 0.123 0.245 -0.245 8 -0.256 0.125 0.249 -0.249 9 -0.149 0.127 0.253 -0.253 10 0.066 0.127 0.254 -0.254 11 0.212 0.127 0.255 -0.255 12 0.279 0.129 0.257 -0.257 13 0.211 0.131 0.262 -0.262 14 0.116 0.132 0.264 -0.264 15 -0.067 0.133 0.265 -0.265

Correlation Little Sarasota Bay Trends Appendix - Display 25

X Correlogram for Total Nitrogen

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Nitrogen 01234 5 6 7 8 9 10 11 12 13 14 15 Little Sarasota Bay Trends Appendix - Display 26 X Seasonal Kendall Tau Trend Test Statistics Total Nitrogen X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.014 0.838 0.82 0Little Sarasota Bay Trends Appendix - Display 27 X Seasonal Kendall Tau Trend Test Statistics Total Nitrogen X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.014493 0.83760 0.82029 0 Adjusted (mg/L) Little Sarasota Bay Trends Appendix - Display 28 X Time Series Plot of Data Adjusted for Season and Detrended Total Nitrogen X

Zero Reference Line Shown -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5

98 99 00 01 02 03 04 05 06 07 08 09 10

Little Sarasota Bay Trends Appendix - Display 29 X Autocorrelation Statistics for Total Nitrogen

X Adjusted for Seasonal Median and Detrended Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.446 0.107 0.213 -0.213 2 0.216 0.113 0.227 -0.227 3 0.048 0.115 0.230 -0.230 4 0.020 0.115 0.230 -0.230 5 0.028 0.115 0.230 -0.230 6 0.039 0.115 0.230 -0.230 7 -0.031 0.115 0.230 -0.230 8 -0.151 0.115 0.230 -0.230 9 -0.137 0.116 0.232 -0.232 10 -0.068 0.117 0.233 -0.233 11 -0.068 0.117 0.233 -0.233 12 -0.029 0.117 0.234 -0.234 13 -0.068 0.117 0.234 -0.234 Little Sarasota Bay Trends Appendix - Display 29 X Autocorrelation Statistics for Total Nitrogen

X Adjusted for Seasonal Median and Detrended Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 14 -0.014 0.117 0.234 -0.234 15 -0.051 0.117 0.234 -0.234

Correlation Little Sarasota Bay Trends Appendix - Display 30 X Correlogram for Total Nitrogen

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Nitrogen 01234 5 6 7 8 9 10 11 12 13 14 15Total Phosphorous (mg/L) Little Sarasota Bay Trends Appendix - Display 31 X Monthly Data Time Series X Total Phosphorous X Not Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Total Phosphorous (mg/L) Little Sarasota Bay Trends Appendix - Display 32 X Monthly Data Time Series X Total Phosphorous X Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5

98 99 00 01 02 03 04 05 06 07 08 09 10

Total Phosphorous (mg/L) Little Sarasota Bay Trends Appendix - Display 33 X X Seasonal Univariate Statistics X Total Phosphorous X X X

0.0 0.1 0.2 0.3 0.4 0.5

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Little Sarasota Bay Trends Appendix - Display 34

X Autocorrelation Statistics for Total Phosphorous

X Unadjusted for Seasonal Medians

X Lagged Total Phosphorous Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.526 0.107 0.213 -0.213 2 0.388 0.116 0.232 -0.232 3 0.361 0.121 0.242 -0.242 4 0.286 0.125 0.250 -0.250 5 0.171 0.127 0.255 -0.255 6 0.190 0.128 0.256 -0.256 7 0.094 0.129 0.259 -0.259 8 0.141 0.130 0.259 -0.259 9 0.172 0.130 0.260 -0.260 10 0.182 0.131 0.262 -0.262 11 0.200 0.132 0.264 -0.264 12 0.119 0.133 0.266 -0.266 13 0.089 0.133 0.267 -0.267 14 0.186 0.134 0.267 -0.267 15 0.097 0.135 0.269 -0.269

Correlation Little Sarasota Bay Trends Appendix - Display 35

X Correlogram for Total Phosphorous

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Phosphorous 01234 5 6 7 8 9 10 11 12 13 14 15 Little Sarasota Bay Trends Appendix - Display 36 X Seasonal Kendall Tau Trend Test Statistics Total Phosphorous X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.325 0 0.022 -.007Little Sarasota Bay Trends Appendix - Display 37 X Seasonal Kendall Tau Trend Test Statistics Total Phosphorous X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.32543 .000000432 0.022159 -.00666667 Adjusted (mg/L) Little Sarasota Bay Trends Appendix - Display 38 X Time Series Plot of Data Adjusted for Season and Detrended Total Phosphorous X

Zero Reference Line Shown 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.20 0.21 0.22 0.23 0.24 0.25 0.26 0.27 0.28 0.29 0.30 0.31 0.32 0.33 0.34

98 99 00 01 02 03 04 05 06 07 08 09 10

Little Sarasota Bay Trends Appendix - Display 39 X Autocorrelation Statistics for Total Phosphorous

X Adjusted for Seasonal Median and Detrended Lagged Total Phosphorous Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.416 0.107 0.213 -0.213 2 0.245 0.113 0.225 -0.225 3 0.255 0.115 0.229 -0.229 4 0.168 0.117 0.233 -0.233 5 0.058 0.118 0.235 -0.235 6 0.080 0.118 0.235 -0.235 7 -0.039 0.118 0.236 -0.236 8 -0.016 0.118 0.236 -0.236 9 0.015 0.118 0.236 -0.236 10 -0.029 0.118 0.236 -0.236 11 -0.012 0.118 0.236 -0.236 12 -0.156 0.118 0.236 -0.236 13 -0.163 0.119 0.238 -0.238 14 -0.038 0.120 0.239 -0.239 15 -0.090 0.120 0.239 -0.239 Correlation Little Sarasota Bay Trends Appendix - Display 40 X Correlogram for Total Phosphorous

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Phosphorous 01234 5 6 7 8 9 10 11 12 13 14 15Chlorophyll a (ug/l) Blackburn Bay Trends Appendix - Display 1 X Monthly Data Time Series X Chlorophyll a X Not Adjusted for Seasonal Medians X

0 10 20 30

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Chlorophyll a

(ug/l) Blackburn Bay Trends Appendix - Display 2 X Monthly Data Time Series X Chlorophyll a X Adjusted for Seasonal Medians X

0 10 20 30

98 99 00 01 02 03 04 05 06 07 08 09 10

Chlorophyll a (ug/l) Blackburn Bay Trends Appendix - Display 3 X X Seasonal Univariate Statistics X Chlorophyll a X X X

0 10 20 30

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Blackburn Bay Trends Appendix - Display 4

X Autocorrelation Statistics for Chlorophyll a

X Unadjusted for Seasonal Medians

X Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.518 0.107 0.213 -0.213 2 0.189 0.116 0.232 -0.232 3 -0.018 0.117 0.234 -0.234 4 -0.132 0.117 0.234 -0.234 5 -0.258 0.117 0.235 -0.235 6 -0.329 0.120 0.239 -0.239 7 -0.311 0.123 0.246 -0.246 8 -0.217 0.126 0.252 -0.252 9 -0.045 0.127 0.255 -0.255 10 0.222 0.127 0.255 -0.255 11 0.367 0.129 0.258 -0.258 12 0.391 0.133 0.266 -0.266 13 0.373 0.137 0.274 -0.274 14 0.239 0.141 0.282 -0.282 15 -0.063 0.142 0.285 -0.285

Correlation Blackburn Bay Trends Appendix - Display 5

X Correlogram for Chlorophyll a

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Chlorophyll a 01234 5 6 7 8 9 10 11 12 13 14 15 Blackburn Bay Trends Appendix - Display 6 X Seasonal Kendall Tau Trend Test Statistics Chlorophyll a X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.229 0 0.037 -0.141Blackburn Bay Trends Appendix - Display 7 X Seasonal Kendall Tau Trend Test Statistics Chlorophyll a X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.22857 .000414614 0.037203 -0.14143 Adjusted (ug/l) Blackburn Bay Trends Appendix - Display 8 X Time Series Plot of Data Adjusted for Season and Detrended Chlorophyll a X

Zero Reference Line Shown -10

0 10 20 30

98 99 00 01 02 03 04 05 06 07 08 09 10

Blackburn Bay Trends Appendix - Display 9 X Autocorrelation Statistics for Chlorophyll a

X Adjusted for Seasonal Median and Detrended Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.350 0.107 0.213 -0.213 2 -0.021 0.111 0.222 -0.222 3 -0.040 0.111 0.222 -0.222 4 0.051 0.111 0.222 -0.222 5 -0.001 0.111 0.222 -0.222 6 -0.076 0.111 0.222 -0.222 7 -0.124 0.111 0.222 -0.222 8 -0.079 0.112 0.223 -0.223 9 -0.026 0.112 0.224 -0.224 10 0.107 0.112 0.224 -0.224 11 0.054 0.112 0.225 -0.225 12 -0.028 0.112 0.225 -0.225 13 0.089 0.112 0.225 -0.225 Blackburn Bay Trends Appendix - Display 9 X Autocorrelation Statistics for Chlorophyll a X Adjusted for Seasonal Median and Detrended Lagged Chlorophyll a Correlation Standard Error Upper Limit Lower Limit 14 0.100 0.113 0.226 -0.226 15 -0.091 0.113 0.226 -0.226

Correlation Blackburn Bay Trends Appendix - Display 10 X Correlogram for Chlorophyll a

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Chlorophyll a 01234 5 6 7 8 9 10 11 12 13 14 15Salinity (ppt) Blackburn Bay Trends Appendix - Display 11 X Monthly Data Time Series X Salinity

X Not Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40 45

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Salinity (ppt) Blackburn Bay Trends Appendix - Display 12 X Monthly Data Time Series X Salinity

X Adjusted for Seasonal Medians X

0 5 10 15 20 25 30 35 40 45

98 99 00 01 02 03 04 05 06 07 08 09 10

Salinity (ppt) Blackburn Bay Trends Appendix - Display 13 X X Seasonal Univariate Statistics X Salinity

X X X

0 5 10 15 20 25 30 35 40 45

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Blackburn Bay Trends Appendix - Display 14

X Autocorrelation Statistics for Salinity

X Unadjusted for Seasonal Medians

X Lagged Salinity Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.592 0.107 0.213 -0.213 2 0.267 0.118 0.237 -0.237 3 0.081 0.121 0.241 -0.241 4 -0.007 0.121 0.242 -0.242 5 -0.058 0.121 0.242 -0.242 6 -0.047 0.121 0.242 -0.242 7 -0.053 0.121 0.242 -0.242 8 -0.079 0.121 0.242 -0.242 9 -0.111 0.121 0.243 -0.243 10 -0.040 0.122 0.243 -0.243 11 0.059 0.122 0.243 -0.243 12 0.074 0.122 0.244 -0.244 13 0.016 0.122 0.244 -0.244 14 -0.043 0.122 0.244 -0.244 15 -0.078 0.122 0.244 -0.244

Correlation Blackburn Bay Trends Appendix - Display 15

X Correlogram for Salinity

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Salinity 01234 5 6 7 8 9 10 11 12 13 14 15 Blackburn Bay Trends Appendix - Display 16 X Seasonal Kendall Tau Trend Test Statistics Salinity

X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.147 0.024 0.284 0.123Blackburn Bay Trends Appendix - Display 17 X Seasonal Kendall Tau Trend Test Statistics Salinity

X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.14675 0.023813 0.28355 0.12313 Adjusted (ppt) Blackburn Bay Trends Appendix - Display 18 X Time Series Plot of Data Adjusted for Season and Detrended Salinity

X

Zero Reference Line Shown -20 -10

0 10

98 99 00 01 02 03 04 05 06 07 08 09 10

Blackburn Bay Trends Appendix - Display 19 X Autocorrelation Statistics for Salinity

X Adjusted for Seasonal Median and Detrended Lagged Salinity Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.557 0.107 0.213 -0.213 2 0.241 0.117 0.234 -0.234 3 0.126 0.119 0.238 -0.238 4 0.066 0.119 0.239 -0.239 5 -0.008 0.120 0.239 -0.239 6 0.016 0.120 0.239 -0.239 7 0.001 0.120 0.239 -0.239 8 -0.012 0.120 0.239 -0.239 9 -0.067 0.120 0.239 -0.239 10 -0.097 0.120 0.240 -0.240 11 -0.085 0.120 0.240 -0.240 12 -0.094 0.120 0.241 -0.241 13 -0.103 0.121 0.241 -0.241 14 -0.097 0.121 0.242 -0.242 15 -0.050 0.121 0.242 -0.242 Correlation Blackburn Bay Trends Appendix - Display 20 X Correlogram for Salinity

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Salinity 01234 5 6 7 8 9 10 11 12 13 14 15Total Nitrogen (mg/L) Blackburn Bay Trends Appendix - Display 21 X Monthly Data Time Series X Total Nitrogen X Not Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Total Nitrogen (mg/L) Blackburn Bay Trends Appendix - Display 22 X Monthly Data Time Series X Total Nitrogen X Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

98 99 00 01 02 03 04 05 06 07 08 09 10

Total Nitrogen (mg/L) Blackburn Bay Trends Appendix - Display 23 X X Seasonal Univariate Statistics X Total Nitrogen X X X

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Blackburn Bay Trends Appendix - Display 24

X Autocorrelation Statistics for Total Nitrogen

X Unadjusted for Seasonal Medians

X Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.544 0.107 0.213 -0.213 2 0.236 0.117 0.233 -0.233 3 -0.033 0.118 0.237 -0.237 4 -0.163 0.118 0.237 -0.237 5 -0.294 0.119 0.239 -0.239 6 -0.322 0.122 0.244 -0.244 7 -0.294 0.125 0.250 -0.250 8 -0.183 0.128 0.256 -0.256 9 -0.053 0.129 0.258 -0.258 10 0.164 0.129 0.258 -0.258 11 0.322 0.130 0.259 -0.259 12 0.364 0.133 0.265 -0.265 13 0.257 0.136 0.273 -0.273 14 0.135 0.138 0.276 -0.276 15 -0.089 0.139 0.277 -0.277

Correlation Blackburn Bay Trends Appendix - Display 25

X Correlogram for Total Nitrogen

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Nitrogen 01234 5 6 7 8 9 10 11 12 13 14 15 Blackburn Bay Trends Appendix - Display 26 X Seasonal Kendall Tau Trend Test Statistics Total Nitrogen X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.126 0.051 0.039 .005Blackburn Bay Trends Appendix - Display 27 X Seasonal Kendall Tau Trend Test Statistics Total Nitrogen X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic 0.12597 0.051368 0.038672 .005 Adjusted (mg/L) Blackburn Bay Trends Appendix - Display 28 X Time Series Plot of Data Adjusted for Season and Detrended Total Nitrogen X

Zero Reference Line Shown -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

98 99 00 01 02 03 04 05 06 07 08 09 10

Blackburn Bay Trends Appendix - Display 29 X Autocorrelation Statistics for Total Nitrogen

X Adjusted for Seasonal Median and Detrended Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.450 0.107 0.213 -0.213 2 0.145 0.114 0.227 -0.227 3 -0.008 0.114 0.229 -0.229 4 -0.042 0.114 0.229 -0.229 5 -0.107 0.114 0.229 -0.229 6 -0.090 0.115 0.229 -0.229 7 -0.126 0.115 0.230 -0.230 8 -0.042 0.115 0.231 -0.231 9 -0.006 0.116 0.231 -0.231 10 0.070 0.116 0.231 -0.231 11 0.108 0.116 0.231 -0.231 12 0.100 0.116 0.232 -0.232 13 0.044 0.116 0.233 -0.233 Blackburn Bay Trends Appendix - Display 29 X Autocorrelation Statistics for Total Nitrogen

X Adjusted for Seasonal Median and Detrended Lagged Total Nitrogen Correlation Standard Error Upper Limit Lower Limit 14 0.017 0.116 0.233 -0.233 15 -0.074 0.116 0.233 -0.233

Correlation Blackburn Bay Trends Appendix - Display 30 X Correlogram for Total Nitrogen

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Nitrogen 01234 5 6 7 8 9 10 11 12 13 14 15Total Phosphorous (mg/L) Blackburn Bay Trends Appendix - Display 31 X Monthly Data Time Series X Total Phosphorous X Not Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5

JAN98 JAN99 JAN00 JAN01 JAN02 JAN03 JAN04 JAN05 JAN06 JAN07 JAN08 JAN09 JAN10 Adjusted Total Phosphorous (mg/L) Blackburn Bay Trends Appendix - Display 32 X Monthly Data Time Series X Total Phosphorous X Adjusted for Seasonal Medians X

0.0 0.1 0.2 0.3 0.4 0.5

98 99 00 01 02 03 04 05 06 07 08 09 10

Total Phosphorous (mg/L) Blackburn Bay Trends Appendix - Display 33 X X Seasonal Univariate Statistics X Total Phosphorous X X X

0.0 0.1 0.2 0.3 0.4 0.5

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Blackburn Bay Trends Appendix - Display 34

X Autocorrelation Statistics for Total Phosphorous

X Unadjusted for Seasonal Medians

X Lagged Total Phosphorous Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.570 0.107 0.213 -0.213 2 0.412 0.118 0.235 -0.235 3 0.529 0.123 0.246 -0.246 4 0.435 0.131 0.263 -0.263 5 0.262 0.137 0.273 -0.273 6 0.298 0.139 0.277 -0.277 7 0.233 0.141 0.282 -0.282 8 0.168 0.142 0.285 -0.285 9 0.155 0.143 0.286 -0.286 10 0.126 0.144 0.288 -0.288 11 0.129 0.144 0.288 -0.288 12 0.052 0.145 0.289 -0.289 13 0.032 0.145 0.289 -0.289 14 0.057 0.145 0.289 -0.289 15 0.097 0.145 0.290 -0.290

Correlation Blackburn Bay Trends Appendix - Display 35

X Correlogram for Total Phosphorous

X Unadjusted for Seasonal Median

X

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Phosphorous 01234 5 6 7 8 9 10 11 12 13 14 15 Blackburn Bay Trends Appendix - Display 36 X Seasonal Kendall Tau Trend Test Statistics Total Phosphorous X Unadjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.283 0 0.082 -.007Blackburn Bay Trends Appendix - Display 37 X Seasonal Kendall Tau Trend Test Statistics Total Phosphorous X Adjusted for Seasonal Medians

Tau Statistic P-Value Without Serial Correlation P-Value With Serial Correlation Slope Statistic -0.28312 .000009705 0.081598 -.00714286 Adjusted (mg/L) Blackburn Bay Trends Appendix - Display 38 X Time Series Plot of Data Adjusted for Season and Detrended Total Phosphorous X

Zero Reference Line Shown 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.26 0.28 0.30 0.32 0.34 0.36 0.38 0.40

98 99 00 01 02 03 04 05 06 07 08 09 10

Blackburn Bay Trends Appendix - Display 39 X Autocorrelation Statistics for Total Phosphorous

X Adjusted for Seasonal Median and Detrended Lagged Total Phosphorous Correlation Standard Error Upper Limit Lower Limit 0 1.000 0.062 0.123 -0.123 1 0.509 0.107 0.213 -0.213 2 0.302 0.115 0.231 -0.231 3 0.432 0.118 0.237 -0.237 4 0.338 0.124 0.248 -0.248 5 0.178 0.128 0.255 -0.255 6 0.215 0.129 0.257 -0.257 7 0.142 0.130 0.260 -0.260 8 0.005 0.131 0.261 -0.261 9 -0.041 0.131 0.261 -0.261 10 -0.078 0.131 0.261 -0.261 11 -0.063 0.131 0.262 -0.262 12 -0.176 0.131 0.262 -0.262 13 -0.177 0.132 0.264 -0.264 14 -0.156 0.133 0.265 -0.265 15 -0.117 0.133 0.267 -0.267 Correlation Blackburn Bay Trends Appendix - Display 40 X Correlogram for Total Phosphorous

X Adjusted for Seasonal Median and Detrended

Zero Reference Line Shown U=Upper 95% Confidence Limit L=Lower 95% Confidence Limit -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

Lagged Total Phosphorous 01234 5 6 7 8 9 10 11 12 13 14 15

# Appendix 4. Residence Time Calculations

# The method used in this effort is predicated on a well-defined flow path for freshwater beginning at the head of an estuary. For a lagoonal system, it is necessary to define the flow path for freshwater entering the estuary at a given point. For the Sarasota Bay Estuary system, two segment groupings were used to represent separate freshwater flow pa ths, defined as follows fo r each grouping (Figure V-9):

• Northern: Palma Sola Bay flows downstream to Sarasota Bay. The northern half of Little Sarasota Bay flows downstream to Roberts Bay, which in turn flows downstream to Sarasota Bay. Sarasota Bay flows downstream to the Gulf of Mexico.

• Southern: Southern half of Little Sarasota Bay flows downstream to Blackburn Bay. Blackburn Bay flows downstream to Dona and Roberts Bay. For each of the segments in these groupings, no n-advective transports were estimated based on observed salinity. Exchange coefficients for non-a dvective transport were estimated using mean water column salinity data, obtained from the FD EP IWR database. The algorithm for exchange coefficients estimation was based on the salinity mass balance equations developed for each segment of the Sarasota Bay Estuary system. The salinity mass balance equations are provided below for each segment, based on the assumption that for a given month, the mass of salinity coming into the segment is balanced by the mass of salinity leaving the segmen t. Here, as in Figure 1, Q is the freshwater inflow to the segment from its watershed, C is the sali nity in the segment, and E is the non-advective exchange rate between two segments. Northern Grouping Palma Sola Bay: 0= -Q PSB 

# C PSB 

# + E SB,PSB 

# (C SB 

# -C PSB 

# ) Little Sarasota Bay North: 0= -0.5Q LSB 

# C LSB 

# + E RB,LSB 

# (C RB 

# -C LSB 

# ) Roberts Bay: 0= -(0.5Q LSB 

# +Q RB 

# )C RB 

# + 0.5Q LSB 

# C LSB 

# + E SB,RB 

# (C SB 

# -C RB 

# ) - E RB,LSB 

# (C RB 

# -C LSB 

# ) Sarasota Bay: 0= -(0.5Q LSB 

# +Q RB 

# +Q SB 

# +Q PSB 

# )C SB 

# + (0.5Q LSB 

# +Q RB 

# )C RB 

# + Q PSB 

# C PSB 

# - E SB,RB 

# (C SB 

# -C RB 

# ) - E SB,PSB 

# (C SB 

# -C PSB 

# ) + E GOM,SB 

# (C GOM 

# -C SB 

# )

Southern Grouping Little Sarasota Bay South: 0= -0.5Q LSB 

# C LSB 

# + E BB,LSB 

# (C BB 

# -C LSB 

# ) Blackburn Bay: 0= -(0.5Q LSB 

# +Q BB 

# )C BB 

# + 0.5Q LSB 

# C LSB 

# – E BB,LSB 

# (C BB 

# -C LSB 

# ) + E DARB,BB 

# (C DARB 

# -C BB 

# ) For the northern grouping, there are four equations and four unknowns, so that the equations can be solved for the non-advective exchange rates (E-values) as follows:

# Sarasota Bay/Palma Sola Bay: E SB,PSB 

# = Q PSB 

# C PSB 

# /(C SB 

# -C PSB 

# ) Roberts Bay/Little Sarasota Bay North: E RB,LSB 

# = 0.5Q LSB 

# C LSB 

# /(C RB 

# -C LSB 

# ) Sarasota Bay/Roberts Bay: E SB,RB 

# = (0.5Q LSB 

# +Q RB 

# )C RB 

# /(C SB 

# -C RB 

# ) Gulf of Mexico/Sarasota Bay: E GOM,SB 

# = (0.5Q LSB 

# +Q RB 

# +Q SB 

# +Q PSB 

# )C SB 

# /(C GOM 

# -C SB 

# ) For the southern grouping, there are two equations and two unknowns, so that the equations can be solved for the non-advective exchange rates (E-values) as follows: Blackburn Bay/Little Sarasota Bay South: E BB,LSB 

# = 0.5Q LSB 

# C LSB 

# /(C BB 

# -C LSB 

# ) Dona and Roberts Bay/Blackburn Bay: E DARB,BB 

# = (0.5Q LSB 

# +Q BB 

# )C BB 

# /(C DARB 

# -C BB 

# ) Monthly exchange coefficients were calculated using hydrologic loading data and salinity concentration data for 1994-2007. The median exc hange coefficients over all months for a given boundary were determined, and used for cal culation of the PRTs, described below. Equations for dilution of a simulated conservativ e tracer were developed based on the methods of Hagy et al. (2000). The PRT was defined as the le ngth of time required to reduce the mass of a tracer in a given segment to e -1 

# times the initial mass. This calculation was performed using the monthly inflows for each month of the 1994-20 07 period, so that a segment-specific PRT was calculated for each month’s inflows. The box model equations for mass balance provided above were used to estimate the change in mass of tracer ( ∆ M) present in each box (segment) of the model for relatively small time increments ( ∆ t=1 hour). The equation for Palma Sola Bay is provided below: Palma Sola Bay: ∆ M PSB 

# = -Q PSB 

# C PSB 

# ∆ t + E SB,PSB 

# (C SB 

# -C PSB 

# ) ∆ t,
with C PSB 

# and C SB 

# updated after each time step until the mass of the tracer in Palma Sola Bay declines to e -1 

# of its original value. Similar equations were used for each of the segments, modifying the mass balance equations provided above to provide tracking of conservative tracer masses in each segment. For the b oundary conditions, the salinity va lues in the Gulf of Mexico and Dona and Roberts Bay were set to 36 ppt, and the tracer mass was set to 0.

# Figure 2-1. Box model schematic for Sarasota B ay Estuary Program. PSB - Palma Sola Bay; SB - Sarasota Bay; RB - Roberts Bay; LSB - Little Sarasota Bay; BB - Blackburn Bay; DARB – Dona and Roberts Bay.

# Appendix 5. Regression Analysis Results