# Site

- Specific Information in Support of Establishing Numeric Nutrient Criteria for the Florida Keys

Florida Department of Environmental Protection Tallahassee, FL 32399

August 18, 2010Nutrient Criteria Technical Support Document Florida Keys

Draft ii August 2010 

### Table of Contents

Executive Summary

............................................................................................................................ 1
Geographic and Physical Description

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

Sources and Fates of Nutrients

........................................................................................................... 7

Nu trient Sources and Loading Estimates

.................................................................................................. 7
Biological Summary

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

Seagrasses

................................................................................................ ............................................... 13
Coral Reefs

................................................................................................ .............................................. 19
Additional Biologica l Resources

.............................................................................................................. 25
Water Quality Studies

...................................................................................................................... 27
Waters on the 303(d) List

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

Numeric Nutrient Criteria Recommendations

................................................................................... 37

FKRAD recommendations

....................................................................................................................... 38

FDEP Nutrient Criteria Approach

............................................................................................................ 40
Proposed Numeric Nutrient Criteria

........................................................................................................ 43
Comparison of FKRAD and FDEP approaches

......................................................................................... 47

References

................................................................................................ ....................................... 50
Appendix A. Permitted facilities and landfills in the Florida Keys basin by planning unit (FDEP 2008b).

................................................................................................ ........................................................ 54Nutrient Criteria Technical Support Document Florida Keys

Draft iii August 2010 

### List of Tables

Table 1. Checklist of nutrient enrichment symptoms in the Florida Keys.

................................................... 3 Table 2. State parks and aquatic preserves.

................................................................................................ 6 Table 3. Estimated annual nutrient loadings in 1999 (lbs year -1 ) for the different Keys regions (FDEP 2008a).

............................................................................................................................. 8 Table 4. Comparison of total 1999 estimated annual anthropogenic land based (wastewater and stormwater) nutrient loadings to the Key s (FDEP 2008a) with some estimated farfield loadings from Florida Bay passes and Atlantic upwelling (Gibson et al. 2008) and atmospheric deposition (calculated using atmospheric loading estimates in Rudnick et al. 1999) in metric tons year -1

. ................................................................................................ . 13 Table 5. Catch statistics for the 15 more abundant reef fish species observed during the Florida Keys visual sampling, 1999

– 200 6.

............................................................................................ 26 Table 6. Water quality variables measured in the FKNMS, March 1995

– December 2008 (Boyer and Briceño 2009).

.................................................................................................................... 30 Table 7. Verified impairments in the Florida Keys basin.

............................................................................ 34 Table 8. Natural background conditions (modeled) and water quality targets for the northern Keys (FDEP 2008a).

................................................................................................................... 38 Table 9. Natural background conditions (modeled) and water quality targets for the central Keys (FDEP 2008a).

........................................................................................................................... 38 Table 10. Natural background conditions (modeled) and water quality targets for the south

central Keys (FDEP 2008a).

....................................................................................................... 39 Table 11. Natural background conditions (modeled) and water quality targets for the southern Keys (FDEP 2008a).

................................................................................................................... 39 Table 12. 1985 FDEP OFW water quality data (FDEP 2008a).

.................................................................... 40

Ta ble 13. Range and means of modeled TN and TP targets for bayside and oceanside bubble WBIDs (FKRAD 2008).

............................................................................................................... 40 Table 14. Proposed regionalization for the Florida Keys.

........................................................................... 41 Table 15. Proposed numeric nutrient criteria for all segments of the Florida Keys, including TP, TN, and chlorophyll a. For compliance purposes, the long term geometric mean shall not exceed the long term limit nor shall the average of all stations in a segment exceed the network average more than twice in a 5 year period. The last column sh ows the value which single station shall not exceed, by segment, more than twice in a 5 year period.

......................................................................................................................... 46 Table 16. Comparison of TN (μg l -1 ) targets for halo zone modeled WBIDs and OFW targets (from the FKRAD) with nearshore FDEP criteria proposed for sub

- basins using FIU long

- term water quality data. For maps showing the locations of WBIDs and sub

- basins, see Figures 24 and 25.

..................................................................................................................... 48 Table 17. Comparison of TP (μg l -1 ) targets for halo zone modeled WBIDs and OFW targets (from the FKRAD) with nearshore criteria prop osed for sub

- basins using FIU long

- term water quality data. For maps showing the locations of WBIDs and sub

- basins, see Figures 24 and 25.

..................................................................................................................... 49Nutrient Criteria Technical Support Document Florida Keys

Draft iv August 2010 

### List of Figures

Figure 1. Map of the Florida Keys and FKNMS boundary.

........................................................................... 5 Figure 2. Regional circulation patterns in the Florida Keys (Lee et al. 2007).

.............................................. 7 Figure 3. Nitrogen loading to Florida Bay and the Florida K eys (Gibson et al. 2008; Key for sources in figure: a. Gibson et al. 2008, b. Boyer and Keller 2007, c. Rudnick et al. 1999, d. Kruczynski and McMannus 2002, e. Leichter et al. 2003).

.......................................... 11 Figure 4. Phosphorus loading to Florida Bay and the Florida Keys (Gibson et al. 2008; Key for sources in figure: a. Gibson et al. 2008, b. Boyer and Keller 2007, c. Rudnick et al. 1999, d. Kruczynski and McMannus 2002, e. Leichter et al. 2003).

.......................................... 12 Figure 5. Conceptual model of the relationship between seagrass leaf nutrient content and nutrient availability in south Florida (Fourqurean and Rutten 2003).

...................................... 15 Figure 6. Conceptual model relating nutrient availability (trophic state) to the abundance of primary producers in nearshore marine waters of south Florida (Fourqurean and Rutten 2003).

............................................................................................................................ 16 Figure 7. EI status of seagrasses in the FKNMS for 2006, 2007, and 2008 compared with the long

- term mean EI (dashed line) for 1995 to 2005 (Fourqurean and Escorcia 2009).

.............. 17 Figure 8. SCI status of seagrasses in the FKNMS for 2006, 2007, and 2008 compared with the long

- term mean SCI (dashed line) for 1995 to 2005 (Fourqurean and Escorcia 2009).

............ 17 Figure 9. Seasonality of epiphyte load, averaged across all 30 Level 1 sites, 2001

– 09 (Fourqurean et al., in press).

.......................................................................................................................... 18 Figure 10. Line graph of mean annual percent cover for the four major benthic taxa recorded in CREMP image analysis (CREMP 2010). Mean percent cover is pooled from 97 stations in the Florida Keys.

.................................................................................................................... 20 Figure 11. Line graph of the mean annual percent cover for six species of stony corals. Mean percent cover is pooled from 97 stations (CREMP 2010).

......................................................... 21 Figure 12. Long term trends of percent cover from 1999

- 2008 at CREMP sites for a) stony corals and b) octocorals (CREMP 2010).

............................................................................................. 22 Figure 13. Number of stations with stony coral disease recorded (Callahan et al. 2007).

........................ 23 Figure 14. Percent cover comparisons between summer 2009 and February 2010 for a) stony corals and b) octocorals at eight stations (CREMP 2010).

........................................................ 24 Figure 15. Mean fish density by year (2000

– 06) as recorded during visual surveys in the Florida Keys (Donahue et al. 2008).

...................................................................................................... 26 Figure 16. Map of study area (Boyer 2010).

.............................................................................................. 28 Figure 17. Florida International University (FIU) Southeast Environmental Research Center (SERC) Water Quality Monitoring Network. Stations in red are sampled as part of the FKNMS monitoring program (Boyer and Briceño 2009).

.......................................................... 29 Figure 18. Median salinity, 1995

– 2009 (Boyer and Briceño 2009).

........................................................... 31 Figure 19. Dissolved inorganic nitrogen (micromolar[μM]) median, 1995

– 2007 (Boyer and Briceño 2009).

........................................................................................................................... 31 Figure 20. TP (μM) median, 1995

– 2007 (Boyer and Briceño 2009).

.......................................................... 32 Figure 21. Chlorophyll a (μg L -1 ) m edian, 1995

– 2007 (Boyer and Briceño 2009).

...................................... 32 Figure 22. Dissolved inorganic nitrogen (μM) (Boyer and Briceño 2009).

................................................. 33Nutrient Criteria Technical Support Document Florida Keys

Draft v August 2010 Figure 23. Map of the Florida Keys with WBIDS and regions (north, central, southcentral, and southern) identified (FDEP 2008a).

........................................................................................... 36 Figure 24. WBID models in the Florida Keys (McClelland 2010).

............................................................... 37 Figure 25. Proposed estuarine and coastal nutrient criteria sub

- basins for South Florida.

....................... 42Nutrient Criteria Technical Support Document Florida Keys

Draft 1 August 2010 

### Executive Summary

This report was prepared by the Florida Department of Environmental Protection (FDEP), in cooperation
with the U.S. Environmental Protection Agency (EPA) and local scientists, to support the development of numeric nutrient criteria for the Florida Keys. T he primary purpose of the proposed numeric nutrient criteria is to protect healthy

, well

- balanced natural populations of flora and fauna from the effects of
excess nutrient enrichment. This report presents approaches for setting criteria for the Florida K eys in
both the halo zone ( within 500 m eters [m] from shore) and nearshore zone waters ( state waters beyond 500 m)

.
The Florida Keys are an archipelago of islands in Monroe County, F lorida, that extend from the southern tip of Florida over 354 kilometers ( km ) to the southwest (Collado

- Vides et al. 2007 ; Figure 1). Consisting of 822 islands, of which about 30 are inhabited, the Keys are traversed by U.S. Highway 1 (a lso known as
U.S. 1 or Overseas Highway) with 19 miles of bridges (FDEP 2008). The Florida Keys National Marine Sanctuary (FKNMS), consisting of 9

, 500 square kilometers ( km 2 ) of coastal and oceanic waters and submerged lands that surround the entire Florida Keys island chain, was established in 1990 ( Figure 1 ). The Keys are generally divided into three geographic areas : the Upper, Middle, and Lower Keys ( Figure
2 ). The three regions are further divided into oceanside and bayside. The bayside regions of the Lower and Middle Keys are known as Backcountry and Sluiceway

, respectively.

There are both anthropogenic and natural sources of local and external nutrient loads to the Keys . The Florida Keys are directly influenced by the Florida Current, the Gulf of Mexico Loop Current, inshore
currents of the Southwest Florida Shelf (Shelf), discharge from the Everglades through Shark River Slough, and tidal exchange with both Florida Bay and Biscayne Bay (Lee et al. 2002). FDEP recognizes
that there are land

- based sources of nutrients in the Keys, such as wastewater and stormwater, which

may contribute to the nutrient regime in waters of the Key s. T he Florida Keys Reasonable Assurance

Document (FKRAD) (FDEP 2008) identified local nutrient sources in the Keys

, including wastewater and stormwater originating from unincorporated Monroe County in the Key Largo area ; the Villages of Islamorada, Marathon, Key Colony Beach, and Layton; the City of Key West ; the Florida Department of Transportation (FDOT ); and the Florida State Park Service. Additionally, in the south

- central and southern Keys

, storm water and wastewater originat e from the U.S. Navy facilities in Boca Chico and
those adjacent to the City of Key West.

The three dominant habitats that make up the coastal marine ecosystems of the Florida Keys are seagrass meadows, coral reefs, and mangroves. Seagrasses are the princip al component of benthic marine habitats in the Keys , occupying over 70% of the FKNMS (Fourqurean et al. 2003 ). Coral reefs, patch reefs, and hardbottom habitats cover approximately 7%, 1%

, and 19% of the FKNMS, respectively. Mangroves are a dominant feature of the land

- sea margin throughout the Florida Keys.

Long

- term monitoring of water quality indicates that nitrate and total organic carbon ( TOC ) follow a concentration gradient, with higher levels in the nearshore area and declining concentrations away from shore, implying a land

- based source (Boyer and Briceño 2009). However, neither total phosphorus ( TP ) nor chlorophyll a concentrations show a trend with distance from land. T he Keys are an extremelyNutrient Criteria Technical Support Document Florida Keys

Draft 2 August 2010 o ligotrophic system and anthropogenic nutrient loads may not be immediately observed in the water column due to rapid assimilation by seagrasses and other benthic flora.

Florida Keys waters were listed as impaired for nutrients on the 1998 303(d) list. However, as provided for in the Impaired Surface Waters Rule (Chapter 62

- 303, Florida Administrative Code [F.A.C.]), the Keys have not been placed on the verified list of impaired waters because local stakeholders provided
documentation that nutrient loa ds from local sources will be reduced as part of a Keys restoration process (see the Florida Keys Reasonable Assurance Document [ FKRAD ] (FDEP 2008a) )

.
For the purposes of nutrient criteria development, FDEP has considered the ha lo zone (within 500 m )
and nearshore zone (state waters beyond 500 m) areas of the Florida Keys separately and is applying

two different approaches for establishing numeric nutrient criteria

.
For the halo zone area, FDEP has yet to develop numeric nutrient criteria, but plans to apply a “response based” approach that is based on the FKRAD document

. As indicated in the FKRAD

, existing canal
nutrient levels and loading from land based sources of nutrients may contribute to the designated uses

not being supported in th e canals (in addition to physical constraints)

. The FKRAD was developed to set forth and accelerate actions that have been taken or are planned to be taken to reduce nutrient loadings throughout the Florida Keys so that water quality standards are met and beneficial uses are restored (FDEP 2008a). The FKRAD is based on improving water quality to targets developed using a
land

- use model . The water quality targets would be assessed at the boundary of the halo zo ne, which is
defined as 500 m from shore. Although the FKRAD does not specifically address criteria for canals, FDEP supports the outlined load reductions i n order to improve water quality at 500 m and help ensure that
criteria are met in nearshore waters

. The FKRAD targets for the halo zone boundary are presented in
Tables 8

- 11 in this report.

For th e nearshore waters , FDEP is applying a “maintain existing healthy conditions” approach. FDEP’s evaluation of the biological resources indicates that the waters support a healthy well

- balanced community, are attaining the designated use, and have not shown adverse effects from nutrient enrichment in the nearshore area. Although there have been changes in some communities (e.g., coral loss) (Tabl e 1), evidence suggests that causes other than nutrients are responsible for the responses.
Waters in the nearshore area will be subdivide d into segments of similar water quality and criteria
established to maintain the current nutrient data distributions, which would continue to support the existing healthy condition. These criteria are presented in Table 15 in this report.Nutrient Criteria Technical Support Document Florida Keys

Draft 3 August 2010 Table 1. Checklist of nutrient enrichment symptoms in the Florida Keys

.

- = Empty cell/no data Response variable Observed historically

or currently ? Explanation Source

Low dissolved oxygen ( DO ) (hypoxia/anoxia) Yes Low DO concentrations have been observed in canals in the Keys and were observed at several nearshore stations during sampling in 1985 for the OFW desi gnation. Diel low DO in SAV beds is a natural phenomenon resulting from SAV respiration. FDEP (2008)

Reduced clarity Yes There has been increased turbidity in nearshore areas, likely due to resuspension of sediments by wind and wave action . However, light penetration to SAV beds generally exceeds 40% of surface values, meaning light is not a limiting factor for SAV growth throughout the Keys

. Boyer and Jones (2002)

Increased chlorophyll a concentrations No C hlorophyll a has not increased over time nor does it vary as a function of distance from land . C hlorophyll a median concentrations are extremely low (0.19 micrograms per liter [ μg l -1 ] ) for the monitoring period between 1995 and 2008. Boyer and Briceño (2009)

Phytopl ankton blooms (nuisance or toxic) Yes Periodic algae blooms originate on the G ulf side of the Keys in Florida Bay or along the southwest Shelf , and are not associated with human activities. The Blackwater event in 2002, resulting from natural tannic inputs into west Florida coastal waters, included a nontoxic algal bloom that was carried south through the Keys. More recent ly, in 2005 and 2006, blooms associated with highway development and hurricane activity were restricted to Barnes Sound and Lake Surprise

. -

Problematic epiphyte growth No Epiphyte growth is highly seasonal

, and recent experimental studies have not found increased epiphytes associated with nutrient additions due to the activity of grazers. e.g. , Fourqurean et al. (in press)

Problematic macroalgal growth No Abundance of calcareous macroalgae in the FKNMS has increased over time

, however, calcareous macroalgae is considered a viable benthic habitat . Sites closest to land and with the highest water column nitrogen ( N) concentrations have the highest calcareous algae abundance. e.g. Lapointe et al. (2004), Collado

- Vides et al. (2005) and (2007), Fourqurean et al. (in press)

S ubmerged aquatic vegetation (S AV ) community changes or loss No Data from the FKNMS monitoring program’s permanent stations indicate no significant sanctuary

- wide decrease in SAV coverage or adverse changes in community composition and show no clear spatial pattern that human activities have resulted in adverse eutrophication effects. Monitoring results indicate that there are early signs of eutrophication within the 500 m halo zone, but those eutrophication effects have not manife sted themselves to where there is imbalance of flora and therefore have not exceeded the narrative criteria. Thal assia tissue nitrogen:phosphorus ( N:P ) ratios are being investigated to determine if this metric may be indicative of early signs of eutrophic ation. e.g. , Fourqurean and Escorcia (2009)

Emergent or shoreline vegetation community changes or loss Yes Shoreline vegetation has changed in many areas where human development has occurred due to physical (not nutrient) disturbance

. -

Coral/hardbottom community changes or loss Yes Coral cover has significantly declined

, and there have been periodic outbreaks of coral disease s (black band and other diseases) in the Keys and throughout the Caribbean . Overall mean percent stony coral cover has been stable since 1999. Changes in c oral health (cover and condition) has not been directly related to anthropogenic land

- based sources of nutrients. Donahue et al. (2008), Callahan et al. (2007) LIrman and Fong (2007)Nutrient Criteria Technical Support Document Florida Keys

Draft 4 August 2010 Impacts to benthic community - Covered above. -

Fish kills Yes P eriodic fish kills have been attributed to factors other than nutrient enrichment (e.g., low DO, red tide , cold, and other factors ). F lorida Fish and Wildlife Research Institute (FWRI )Nutrient Criteria Technical Support Document Florida Keys

Draft 5 August 2010 

### Geographic and Physical Description

The Florida Keys are an archipelago of is lands in Monroe County, F lorida, that extend from the southern tip of Florida over 354 km to the southwest (Collado

- Vides et al. 2007 ; Figure 1 ). About 30 of the 822 islands are inhabited and the Keys are traversed by U.S. Highway 1 with 19 miles of bridges (FDEP 2008). Approximately 34% of the land area in the Keys portion of Monroe County is conserved (Monroe County 2010).

The Florida Keys was designated an Outstanding Florida Water ( OFW ) in 1985 , and i n 1990
, t he the entire Florida Keys island chain and the 9,500 km 2 of coastal and oceanic waters and submerged lands
that surround it were established as the Florida Keys National Marine Sanctuary ( Figure 1 ). The Keys are bordered to the north and northwest by Biscayne National Park and Everglades National Park. There are
also 2 aquatic preserves and 10 state parks located in the Keys ( Table 2).

The Florida Keys region is underlain by the extremely permeable Key Largo Formation limestone

, and the Keys have little vertical relief (5 m eter maximum at Windley Key). Soils quickly infiltrate runoff and its pollutants are transported rapidly to nearshore waters with little or no nutrient entrapment in the
soil mat rix (FDEP 2008). The islands function as a discontinuous, semipermeable dam that separates Florida Bay from the Atlantic Ocean (Reich et al. 2002).

The Keys are generally divided into three geographic areas: the Upper, Middle, and Lower Keys ( Figure
2 ). The Lower Keys are most influenced by cyclonic gyres that spin off the Florida Current, the Middle Keys by exchange with Florida Bay, and the Upper Keys by Florida Current frontal eddies and somewhat by exchange with Biscayne Bay ( Figure 2 ; Boyer and Briceño 2008). The three regions are further divided into oceanside and bayside. The bayside regions of the Lower and Middle Keys are known as Backcountry and Sluiceway, respectively.

Figure 1. Map of the Florida Keys and FKNMS boundary.Nutrient Criteria Technical Support Document Florida Keys

Draft 6 August 2010 Table 2

. State parks and aquatic preserves.

Name Description

Coupon Bight Aquatic
Preserve **•** 4,600 acres of seagrass meadows, hard bottom communities, mangrove wetlands

, and coral reefs

**•** The patch reef community includes sponges, soft and hard corals, and algae

**•** Home to rare wading birds and the endangered Key d eer

Lig n umvitae Key Aquatic
Preserve **•** 7,000 acres of seagrass meadows, deep water channels, hard

- bottom communities and mangrove wetlands

**•** Lignumvitae Key Botanical State Park overlaps with much of the preserve

Dagny Johnson Key Largo Hammock Botanical State Park **•** Contains one of the largest tracts of West Indian tropical hardwood hammock in the U nited States

**•** Home to 84 protected species of plants and animals

John Pennekamp Coral Reef State Park **•** First underwater park in the U nited States

**•** 70 nautical square miles with coral reefs and associated marine life

**•** Upland area includes mangrove swamps and tropical hammocks

Windley Key Fossil Reef Geological State Park **•** Formed of Key Largo limestone, fossilized coral

**•** Historically was a quarry used for stone to build the Flagler Railroad

Indian Key Historic State Park **•** Tiny island accessible only by canoe or kayak

San Pedro Underwater Archaeological Preserve State Park **•** Underwater archeological preserve that features a submerged shipwreck

Lignumvitae Key Botanical State Park **•** Virgin tropical hardwood hammock only accessible by boat

Long Key State Park **•** Profusion of plant and animal life

**•** Known for bonefishing

Curry Hammock State Park **•** Group of islands

**•** Hardwood hammocks support a large population of thatch pines

**•** Other communities include mangrove swamps, seagrass beds

, and wetlands

Bahia Honda State Park **•** Site of hawksbill turtle nesting

Fort Zachary Taylor Historic State Park **•** Fort was constructed in the mid

- 1800s to defend the nation’s southern coastlineNutrient Criteria Technical Support Document Florida Keys

Draft 7 August 2010 Figure 2

. Regional circulation patterns in the Florida Keys (Lee et al. 2007 ).



### Sources and Fates of Nutrients

Nutrient Sources and Loading Estimates

The w ater quality of the FKNMS can be directly affected both by local nutrient loading sources and external nutrient transport (Boyer and Briceño 2009 ). There are both anthropogenic and natural
sources for the local and external nutrient loads. The FKNMS is directly influenced by the Flo rida Current, the Gulf of Mexico Loop Current, inshore currents of the Shelf , discharge from the Everglades through Shark River Slough, and tidal exchange with both Florida Bay and Biscayne Bay ( Lee et al. 2002). Advection from these external sources sign ificant ly a ffects the physical, chemical, and biological composition of waters within the FKNMS, as does internal nutrient loading and freshwater runoff from the Keys themselves (Boyer and Jones 2002).

Local anthropogenic nutrient sources within the Keys include point source discharges (domestic wastewater) and nonpoint source inputs, such as septic tanks and stormwater. The FKRAD ( FDEP 2008 a ) identified local nutrient sources in the Keys

, including wastewater and stormwater originating in unincorporated Monroe County in the Key Largo area ; the Villages of Islamorada, Marathon, Key Colony Beach, and Layton ; the City of Key West ; the Florida Department of Transportation (FDOT ); and the
Flori da State Park Service. Additionally, in the south

- central and southern Keys

, stormwater and wastewater originat e in the U.S. Navy facilities both in Boca Chico and those adjacent to the City of KeyNutrient Criteria Technical Support Document Florida Keys

Draft 8 August 2010 West. Table 3 provides a summary of the estimated contr ibution of nutrients from wastewater and stormwater to WBIDS in the north, central, south

- central, and southern regions of the Keys for the baseline time period of 1999. Load estimates were calculated as part of the Florida Keys Carrying Capacity Study based on the number of equivalent dwelling units ( EDUs ) , their estimated daily flows and
the effluent characteristics of their wastewater treatment methods. Table 4 provides load estimate totals by regions converted to metric tons per year (m tons year -1 ) f or comparison with estimates of
farfield nutrient sources.

The 2008 Water Quality Assessment Report for the Florida Keys provides the following information on permitted discharges within each planning unit (FDEP 2008b; a full list of discharging facilities is provided in Appendix A). In the Upper Keys planning unit t here are 147 permitted wastewater facilities, of which 139 are domestic waste facilities, five ar e industrial waste facilities, two are industr ial stormwater discharges, and one is an underground injection control facility. Of these facilities, only two discharge to state su rface waters, and those are the stormwater dis charges

. There are 91 permitted

wastewater facilities in the Middle Keys planning unit, of which 83 are domestic waste facilities, six are in dustrial waste facilities, and two are industrial stormwater discharges. Of these facilities, two discharge to state surface waters, and those are the st ormwater discharges. There are 57 permitted wastewater facilities in the Lower Keys Planning Unit, of which 51 are domestic waste facilities, five are industrial waste facilities, and one is an industrial stormwater discharge. Three of these facilities discharge to state surface waters: one domestic waste facility, one industrial waste facility, and one stormwater discharge. There are two inactive solid waste landfills in the Upper Keys planning unit, in the Middle Keys there are two solid waste landfills, one active and one inactive; and in the Lower Keys there are four landfills, two active and two inactive; however, the solid waste is currently sent to the mainland for disposal. There are no hazardous waste sites, Superfund sites, state

- funded waste cleanup sites, or delineated ground water contamination areas in the Up per Keys, Middle Keys, or Lower Keys Planning Units.

Table 3. Estimated annual nutrient loadings in 1999 ( lbs year -1 ) for the different Keys regions (FDEP 2008 a).

WBID Wastewater Stormwater
TN TP TN TP Northern
6006A -N 66,869 19,324 21,469 3,310
6006A -S 67,601 19,643 28,338 4,442
6006B -N 585 167 19,985 3,257
6006B -S 1,847 497 4,489 721
6006C

- N 12,488 3,747 4,477 748
6006C -S 6,522 1,956 5,247 810
6009 -N 30,541 8,829 8,988 1,288
6009 -S 23,975 6,899 4,557 634
6017 -N 12,643 3,709 3,035 423
6017 -S 16,149 4,823 3,058 398
6019 -N 7,920 2,315 3,496 574Nutrient Criteria Technical Support Document Florida Keys

Draft 9 August 2010 6019 -S 4,462 1,413 1,402 227 Northern - Total 251,573 73,346 108,842 16,832

Central
6010 -N 5,180 1,546 1,740 251.18
6010

- S 1,357 407 2,935 462.49
6011A -N 5,180 1,546 1,740 251.18
6011A

- S 1,357 407 2,935 462.49
6011B -S 38,089 9,665 9,433 1,502.94
6011C -N 9,043 2,688 2,514 385.03
6011C -S 4,146 1,200 1,558 238.10
6016 -N 802 233 142 20.30
6016

- S 7,492 2,248 1,958 281.17 Central - Total 129,856 35,288 34,848 5,529 Southcentral
6012A 30,009 8,943 21,362 3,353
6012C 193 58 2,842 460
6012D 346 104 1,280 205
6012E 1,175 343 3,113 511
6013A 11,971 3,558 22,724 3,806
6013B 632 188 843 132
6013C 28,183 8,162 15,223 2,449
6013D 82 25 787 128
6014C 25,498 7,532 23,910 4,566
6018 2,388 716 3,085 480 Southcentral - Total 100,477 29,629 95,169 15,650

Southern
6014A -N 114,276 34,283 12,491 1,730
6014A -S 62,651 18,797 10,516 1,603
6014B -N 9,191 2,754 3,289 474
6014B -S 23,100 8,775 4,349 619 Southern - Total 209,218 64,609 30,645 4,427

Submarine ground water d ischarge is also a component of nutrient input in the Keys (Lapointe et al. 1990, Lapointe and Matzie 1996). Lapointe et al. (1990) assessed the degree of nutrient enrichment of limestone ground waters by onsi te sewage disposal systems (septic tanks) and evaluated seasonal relationships between nutrient

- enriched ground waters and adjacent surface waters. They observed that ground waters associated with septic tanks had elevated nutrient concentrations compared with
controls.

Reich et al. (2002) verified the natural gradient flow of ground water from Florida Bay beneath Key Largo and ultimately into the Atlantic Ocean using multi

- depth wells and the injection of fluorescein andNutrient Criteria Technical Support Document Florida Keys

Draft 10 August 2010 rhodamine dyes as tracers. The study included clusters of deep (13.6 m) and shallow (6.1 m) wells on the bayside and oceanside of an undeveloped area of Key Largo. They observed that the greatest forcing factor in ground water movement is the difference in water level between Florida B ay and the Atlantic Ocean. For over 6 months, Florida Bay was on average 12 to 15 centimeters (cm) higher than the Atlantic side. There was both horizontal and vertical flow of ground water, with the predominant
direction of horizontal flow to the southe ast, towards the reef tract. Their results indicate that a component of vertical flow likely contributes ground water seepage up into overlying surface waters and could transport nutrients and pollutants into nearshore waters as well as to the reef tract.

External sources of nutrients to the Keys include the natural and regulated discharges from the Everglades to Florida Bay , regulated discharges from Lake Okeechobee through the Pea ce River, Caloosahatchee River and Mississippi River discharges to the Gulf of Mexico, Atlantic upwelling, and atmospheric deposition ( FDEP 2008 a ; Lapointe et al. 2004).

Lapointe et al. (2004) quantified the role of physical forcing and water management in south Florida on
nutrient enrichment and blooms o f phytoplankton, macroalgae, and seagrass epiphytes in the Keys. Results suggested that regional

- scale agricultural runoff (from the mainland Everglades watersheds) and local sewage discharges from the Keys are both significant N sources. However, Gibso n et al . (2008) determined that while the Middle Keys passes were a significant outflow from Florida Bay towards the reef tract, inputs of cool, nutrient rich waters via offshore tidal bores contribute d far greater amounts of biologically available N direc tly to the reef system. For P, fluxes across the open western boundary of Florida Bay and input from tidal bores are also important nutrient sources to the reef system. Gibson et al. (2008) quantified the exchange of water and nutrients through Long Key Channel using long

- term, high

- resolution, mass flow measurements

, combined with periodic tidal

- scale observations of nutrient
concentrations . Loads were compared with other published values of regional nutrient loads and fluxes ( Figure s 3 and 4).Nutrient Criteria Technical Support Document Florida Keys

Draft 11 August 2010 Figu re 3. Nitrogen loading to Florida Bay and the Florida Keys (Gibson et al. 2008; Key for sources in figure: a. Gibson et al. 2008, b. Boyer and Keller 2007, c. Rudnick et al. 1999, d. Kruczynski and McMannus 2002, e.
Leichter et al. 2003 ). 5190 **NO 3** 

**- 13000**  250 **710** 1240

5500 500 **640**



### ~2000 km 2 **8800** 

### TN Inputs and Outputs (Metric Tons/year)

5190 **( e )**
**NO 3**  **-** “ 13000 ” **( c**  **)** 250 **( b**  **)**

“ 710 ” **( c**  **)** 1240 **( b )** 

3500 **( b )**
5500 **( a )** 500 **( d**  **)** “ 640 ” **( c )**

“ 8800 ” **( b )** 

### TN Inputs and Outp uts (Metric Tons/year)Nutrient Criteria Technical Support Document Florida Keys

Draft 12 August 2010 Figure 4. Phosphorus loading to Florida Bay and the Florida Keys (Gibson et al. 2008; Key for sources in figure: a. Gibson et al. 2008, b. Boyer and Keller 2007, c. Rudnick et al. 1999, d. Kruczynski and McMannus 2002, e.
Leichter et al. 2003 ).

Table 4 shows a comparison of the 1999 anthropogenic land based nutrient loads (Table 3 totals for
stormwater and wastewater ; FDEP 2008 a ) converted to metric tons per year to compare with some farfield estimates of nutrient loads to the region from Gibson et al . (2008) an d Rudnick et al . (1999)

. Land based nutrient sources are a small component of the total nutrient inputs to the Keys. **NO 3** 

**- 13000**  250 **710** 1240

5500 500 **640**



### ~2000 km 2 **8800** 

### TN Inputs and Outputs (Metric Tons/year)

86 1 **( e )** “ 5 00 ” **( c**  **)** 3 **( b**  **)**

“ 38 ” **( c**  **)** 1 0 **( b )** 

87 **( b )**
90 **( a )** 1 63 **( d**  **)** “ 3 4 ” **( c )**

“ 3 8 ” **( b )** 

### T P Inputs and Outp uts (Metric Tons/year)Nutrient Criteria Technical Support Document Florida Keys

Draft 13 August 2010 Table 4

. Comparison of total 1999 estimated annual anthropogenic land based (wastewater and stormwate r)
nutrient loadin gs to the Keys (FDEP 2008 a) with some estimated farfield loadings from Florida Bay passes and Atlantic upwelling (Gibson et al. 2008) and atmospheric deposition (calculated using atmospheric loading estimates in Rudnick et al. 1999) in metric tons year -1

.

- = Empty cell/no data Source TN (metric tons year -1 ) TP (metric tons year -1 ) Keys wastewater and stormwater 438 111.8

Atlantic upwelling 5190 861

Florida Bay (through Middle Keys passes) 5500 90

Atmospheric deposition 3040 161.5



### Biological Summary

The three dominant habitats that make up the coastal marine ecosystems of the Florida Keys are seagrass meadows, coral reefs, and mangroves. Seagrasses are the princip al component of benthic
marine habitats in the Keys

, occupying over 70% of the FKNMS (Fourqurean et al. 2003). Coral reefs, patch reefs, and hardbottom habitats cover approximately 7%, 1%

, and 19% of the FKNMS, respectively

. Mangroves are a dominant feature of the land

- sea margin throughout the Florida Keys.

Seag rasses

The dominant primary producers in the Keys are seagrasses and macroalgae. One of the world’s most extensive seagrass beds, approximately 14,000 km 2 , surrounds the Florida Keys (Fourqurean and Zieman 2002). The structure and distribution of seagras s communities varies throughout the Keys. Seagrass es form extensive meadows and patchy beds, and are also found scattered throughout other habitats (Fourqurean et al . 2001)

. The distribution and species composition of seagrasses in south Florida results from many factors, with the most important being water depth, water clarity, and nutrient availability (Fourqurean et al. 2002).

Seagrass beds are important habitat for other species

, including pink shrimp ( Farfantepenaeus) , spiny lobster ( Panulirus argus ), queen conch ( Strombus gigas ), and spotted seatrout ( Cynoscion nebulosus ) (Fourqurean et al. 2001). Lapointe et al. (1994) note that

, since the densities of benthic invertebrates and fishes that inhabit seagrass meadows are positively correlated wi th seagrass density and productivity, the eutrophication of seagrass meadows could also lead to reductions in secondary productivity.

Fourqurean et al. (2001) documented the distribution and abundance of seagrasses in south Florida in a larger study area t hat included the FKNMS from 1995 to 1998 and found T. testudinum to be the mostNutrient Criteria Technical Support Document Florida Keys

Draft 14 August 2010 common seagrass at 67.2% of the sites. Other seagrasses observed included Syringodium filiforme at 38.9% of the sites and Halodule wrightii and Halophila decipens at about 15% at each site. A survey of seagrass species composition and density in the FKNMS from 1996 to 1997 found water depth related to the density of all observed seagrass species except for Halophila engelmanni

. The densities of
T. testudinum

, H. wrightii , a nd Ruppia maritime were higher in shallow water, while S. filiforme and H. decipens density were higher in deeper water (Fourqurean et al. 2002).

There is typically a gradient of water column and sediment nutrient availability, with low N offshore and low P nearshore (Boyer and Jones 2002; Szmant and Forrester 1996). In seagrass

- dominated systems, it
can be difficult to determine the actual nutrien t status of the water column because of the rapid uptake of soluble nutrients (Tomasko and Lapointe 1991). The ratio of N:P in seagrass leaf tissues has been used to infer the relative availability of nutrients and spatial patterns in limiting nutrients ( Fourqurean
and Zieman 2002 ; Burkholder et al. 2007). Fourqurean and Zieman (2002) sampled T. testudinum in the Keys and observed strong spatial patterns in the relative amount of N and P in tissues. On the Gulf side of the Keys, the N:P ratios indicated P limitation

, except at the western margin of Florida Bay. There was also a signal of P

- limitation in the nearshore area along the Atlantic side of the Keys ; however

, farther offshore the ratios indicated N limitation. It is important to note that factor s other than nutrient availability, such as variation in light availability or any other factor that limits growth rate, can affect the nutrient content of seagrass tissue. The spatial patterns of N:P ratios in this study are consistent with
estimates of nutrient loading in different areas and sediment nutrient ratios.

The results of a 14

- month fertilization experiment in the FKNMS indicated that there are taxon

- specific responses to nutrient enrichment and that nutrient limitation differs for nearshore a nd offshore sites and for seagrass and algae (Ferdie and Fourqurean 2004). The authors measured the response of seagrasses, macroalgae, epiphytes

, and microalgae to additions of N and P fertilizer to assess gradients
of nutrient limitation nearshore and o ffshore in the Florida Keys. Sites were located on the east side of the upper Keys between the Keys and the reef tract. Fertilization increased both sediment nutrient content and plant nutrient content. There was rapid uptake of N by T. testudinum at bo th nearshore and offshore sites, but compared with N, P uptake was delayed. There was an increase in T. testudinum leaf length, standing crop, and growth rates in response to N, but not P, at offshore sites, implying that

seagrass es in offshore habitats i n the upper Keys are N limited. However, there was no clear increase in biomass or primary productivity of seagrasses at nearshore sites in response to added P. Overall,
nutrient enrichment resulted in increase d seagrass biomass at offshore sites and increase d macro algal and sediment microalgal biomass at nearshore sites

.
Seagrasses have been monitored in the FKNMS since 1995 (Fourqurean and Escorcia 2009). The FKNMS seagrass monitoring program collects data on the distribution and abundance of seagrasses and other benthic plants and animals, seagrass tissue nutrient concentration and isotopic composition, and water quality (Fourqurean and Escorcia 2009). The general objective of the seagrass monitoring is to measure the status and trends of seagrass communities to evaluate progress toward protection and restoration of the living marine resources (Fourqurean and Escorcia 2009 ).Nutrient Criteria Technical Support Document Florida Keys

Draft 15 August 2010 The FKNMS uses two indicator criteria to assess status and trends in the seagrass communities. The first criterion, called the elemental indicator ( EI ), is based on a conceptual model that predicts that T.
testudinum is likely to be replaced by faster

- growing competitors if nutrient availability is such that leaf
tissue concentration is near the critical N:P ratio of approximately 30:1. An N:P ratio of 30:1 in seagrass leaves hypothetically indicates a balance in the availability of N and P, and monitoring deviations from this ratio can be used to infer whether N or P are limiting this species’ growth. This indicator is based on the hypothesis that change in the N:P ratio over time, from an N or P limited ratio to a value closer to 30:1, could indicate eutrophication (Figure 5).

EI is calculated from the mean absolute difference in N: P from the ideal 30:1 for the 30 permanent monitoring sites based on the 10

- year (1995

– 2005) mean N:P ratio at each of those sites.

Figure 5. Conceptual model of the relationship between seagrass leaf nutrient content and nutrient availability
in south Florida (Fourqurean and Rutten 2003).

The second indicator criteri on , the Species Composition Indicator ( SCI ) , measures whether the
abundance of the slowest- growing seagrass species, T. testudinum , has changed compared with the
abundance of other sea grass species. The SCI is based on a dominance

- eutrophication gradient conceptual model

, where each of the six seagrass species can potentially dominate over a range of nutrient availability (Figure 6) . T he conceptual model predicts that species dominance will change as

n utrient availability changes. However, f ield evidence suggests that species replacements may take place over a decade or more , making it difficult to relate the model prediction to observed response (Fourqurean and Escor cia 2009)

. The model predict s that the first responses to eutrophication w ould beNutrient Criteria Technical Support Document Florida Keys

Draft 16 August 2010 evidenced by an increase in the relative abundance of fast er

- growing seagrass species ( H. wrightii and S. filiforme ) at the expense of the now

- dominant, slow

- growing T. test udinum . At later stages of eutrophication , macroalgae and microalgae would become the dominant primary producers.

Figure 6. Conceptual model relating nutrient availability (trophic state) to the abundance of primary producers in nearshore marine waters of south Florida (Fourqurean and Rutten 2003).

The change in T. testudinum abundance compared with other species at a site is defined as “ SLOW .”
The distribution and abundance of seagrasses are measured using rapid assessment Braun

- Blanquet

surveys. The SCI is defined as the mean of SLOW over the 30 monitoring sites, where:

A Tt = long

- term mean abundance of T. testudinum

A Sf = long

- term mean abundance of S. filifo rme
A Hw = long

- term mean abundance of H. wrightt i
A macroalgae = long

- term mean abundance of macroalgal taxaNutrient Criteria Technical Support Document Florida Keys

Draft 17 August 2010 The long

- term ( 1995

– 2005 ) EI is 8.28 ± 1.47 (± 1 standard error) and the long

- term SCI is 0.48 ± 0.04 (± 1
standa rd error). Despite a slight decreasing trend in t he mean values for both the EI and SCI for 2007
and 2008 , the means were all within the confidence estimate of the long

- term a verages for 1995 to
2005 (Figures 7 and 8). Since the EI and SCI are not significant ly diffe rent from the lo ng

- term mean , these indices suggest that there have been no significant adverse seagrass responses to nutrients for
2006

- 2008 across the FKNMS.

Figure 7. EI status of seagrasses in the FKNMS for 2006, 2007, and 2008 compared with the long

- term mean EI (dashed line) for 1995 to 2005 (Fourqurean and Escorcia 2009).

Figure 8. SCI status of seagrasses in the FKNMS for 2006, 2007, and 2008 compared with the long

- term mean SCI (dashed line) for 1995 to 2005 (Fourqurean and Escorcia 2009).

I ncreased macroa lgal abundance , coincident with increased N concentrations, and in some cases, increased epiphyte productivity has been observed in nearshore areas of the Keys ( Lapointe et al. 1994;
Collado

- Vides et al. 2005 ; Collado

- Vides et al. 2007)

. Lapointe et al. (1994) observed higher epiphyte
loads on T. testudinum and H. wrightii at sites closer to shore than at more oligotrophic offshore sites.
Collado

- Vides et al. (2005) sampled seagrass and macroalgal abundance quarterly from 1996 to 2002 at
28 of the 30 permanent sites in the FKNMS and found the only significant gradient was with distance from land, with sites closer to land showing higher values. The principal species of calcareous green algae in the seagrass meadows were Halimeda incras sata , H. monile

, H. tuna
, H. opuntia
, PenicillusNutrient Criteria Technical Support Document Florida Keys

Draft 18 August 2010 capitatus
, P. dumetosus

, P. pyryformis

, Rhipocephalus phoenix

, Udotea cyathiformis , and U. flabellum

. Each genus had a unique distribution and seasonal pattern of abundance, with lower abundance in
winter a nd higher abundance in summer. In addition, the 4 genera studied increased in abundance at
most sites over the 7- year study period. Regional

- scale gradients in environmental conditions, such as salinity and water temperature, did not appear to influence abundance

. The higher values of the long term trend closer to land could suggest that nutrient influx from land.

Collado

- Vides et al. (2007 ) used data from the long

- term seagrass monitoring program and the water quality monitoring program in the FKNMS to detect the long

- term abundance trends of macroalgae groups and their correlations with median nutrient concentrations for the 30 permanent monitoring sites between March 1996 and May 2003. Their analyses suggest that the abundance and long

- term
increases in abundance of major macroalgal groups in the FKNMS were highest in areas with the highest availability of N. The dominant group in the seagrass beds was calcareous green algae, dominated by
Halimeda , followed by the “red other” group, dominated by Laurencia

. Results indicated that the abundance of almost all macroalgae groups was increasing over the course of the study , suggesting a

“ slow and steady ” increase of slow

- growing calcareous green algae, as opposed to bloom condition.

Elevated epiphyte loads on seagrass have been observed under eutrophic conditions and in response to N and P fertilization (Tomasko and Lapointe 1991; Lapointe et al. 1994; Ferdie and Fourqurean 2004). Epiphyte loads on seagrasses in the FKNMS are highly seasonal, with peaks in early spring and minimum abundance in early fall (Figure 9; Fourqurean and Escorcia 2009; Fourqurean et al. in press; Lapointe et al. 1994). However, Fourqurean et al. (in press) did not find a correlation between epiphyte load on turtle grass, T. testudinum, and water column or sedimen t nutrient concentrations. Fourqurean et al . (in press) propose that the top

- down grazer removal of epiphytes may obscure the influence of nutrients on the epiphyte community.

Figure 9. Seasonality of epiphyte loa d, averaged across all 30 Level 1 sites, 2001

– 09 (Fourqurean et al., in press).Nutrient Criteria Technical Support Document Florida Keys

Draft 19 August 2010 As noted previously, the seagrass beds in the Florida Keys are part of one of the most extensive SAV
beds in the world. Indices used for the s eagr ass monitoring program in the FKNMS indicate no decreased coverage or abundance of seagrass throughout the sanctuary. The various indicators used in the FKNMS seagrass monitoring program show no statistically significant change in N:P ratios or community composition, when comparing the 2006 to 2008 period with 1995 to 2005 conditions (Fourqurean and Escorcia 2009). Although there have been observations of Increased calcareous macroalgal growth , it is limited to nearshore areas and is correlated with areas that receive increased N loading ( e.g. Collado

- Vides et al. 2007). Note that calcareous algae are considered a viable benthic
habitat. Additionally, despite the slow increase in macroalgal abundance at nearsh ore sites, the community composition and coverage of seagrass overall in the FKNMS has not changed since monitoring began in 1995 (Collado

- Vides et al. 2007; Fourqurean and Escorcia 2009)

.
Coral Reefs

The information in the following section is summarized from the State of Coral Reef Ecosystems of the Florida Keys report (Donahue et al. 2008), the 2006 Executive Summary of the Coral Reef Evaluation and Monitoring Project (CREMP) (Callahan et al. 2007), the 2010 US EPA Water Quality Protection Program Steering Committee Presentation (Ruznicka et al . 2010) and the CREMP EPA Steering Committee Meeting Presentation Summary (CREMP 2010).

There have been numerous studies that report loss of coral in recent de cades. For example, Chiappone and Sullivan (1994) reported changes observed after 4 years of monitoring, from 1989

- 1992, at two hardbottom sites in the Keys. The Craig Key site (CKS) is located about 100 m offshore on the Atlantic side of Craig Key. The Fiesta Key site (FKS) is located about 100 m from the shore on the FL Bay side of Fiesta Key. At each site, benthic organsims were estimated visually in 1 m 2 quadrats and included algae, sponges, octocorals, and stony corals. During the study period, th ere were reductions in species numbers and abundance at the FKS. At the CKS, there were increases in abundance of sessile benthic invertebrates, with the exception of a loss of coral coverage during 1990

- 91 due to the mortality of Millepora alcicornis (en crusting fire coral) colonies.

The Florida Fish and Wildlife Research Institute collects annual data on the status of coral habitats in the Florida reef tract through the Coral Reef Evaluation and Monitoring Project (CREMP), which began monitoring with 40 sites in 1996 and has since expanded to include sites in the Dry Tortugas and along the SE coast (Ruznicka et al . 2010, Donahue et al. 2008; Callahan et al. 2007). CREMP sites encompass four reef habitat categories: hardbottom, patch reef, and offshore deep and shallow reefs. The following summarizes the main long

- term trends in benthic cover from 1999

- 2008 and recent changes from 2008 to 2009 (CREMP 2010, Ruznicka et al . 2010).

Overall t rends in percent cover from 1999 to 2008 were determined from a g eneralized mixed model regression ( F igure 1 0 ). Stony coral and sponge were both decreasing (p<0.001), octocoral was increasing (p<0.001), and there was no change in macroalgae percent cover (p<0.05) (CREMP 2010). Macroalgae cover has been highly variable, but mean cover throughout the project is ~11% ( Figure 1 0 ). However, a significant increase in stony coral was observed between 2008 and 2009, for the first time in CREMP’s monitoring history.Nutrient Criteria Technical Support Document Florida Keys

Draft 20 August 2010 Figure 10. L ine graph of mean annual percent cover for the four major benthic taxa recorded in CREMP image analysis (CREMP 2010) . Mean percent cover is pooled from 97 stations in the Florida Keys.

Five of the six most spatially dominant species of stony corals show ed a significant decreasing trend in percent cover over the period 1996 to 2009 ( F igure 1 1 ). The only exception is Siderastrea siderea, which does not show any significant change. Decreasing trends were observed for Monastraea annularis (p<0.001), Monast raea cavernosa (p<0.001), Porites astreoides (p<0.001) and Colpophyllia natans (p<0.001) while there was no change in Siderastrea sidereal (p>0.05)

.
The negative trends for the M. annularis complex are most evident in the Lower Keys and Dry Tortugas.
Over all, 43% (16 of 37) of all CREMP sites showed a negative trend and 69% (11 of 16) of the sites showing the negative trend are located in the Lower Keys and Tortugas regions ( F igure 1 2 ).Nutrient Criteria Technical Support Document Florida Keys

Draft 21 August 2010 Figure 11 . Line graph of the mean annual percent cover for six species of stony corals. Mean percent cover is pooled from 97 stations (CREMP 2010).Nutrient Criteria Technical Support Document Florida Keys

Draft 22 August 2010 Figure 12

. Long term trends of percent cover from 1999

- 2008 at CREMP sites for a) stony corals and b) octocorals (CREMP 2010).

Soft coral, or octocoral, cover has significantly increased during the past 10 years after reaching a low point in 1999. Cover of soft corals declined during the initial four years of the project, but has increased every year from 1999 through 2004 ( F igure 1 2 ). Although cover dipped again due to hurricane damageNutrient Criteria Technical Support Document Florida Keys

Draft 23 August 2010 between 2005 and 2007, it was 14.8% in 2009, the highest value ever reported by CREMP. The pattern
of increased octocoral cover is most evident at the shallow forereef sites and coincides with the loss of Acropora palmata and Millepora complanata from these habitats during the mass bleaching and disease
outbreaks that occurred from 1997

- 2000 (CREMP 2010).

The incidence of black band disease peaked in 1998, and this disease has not been recorded at more
than 10 stations since t hen (Figure 13). White diseases and “other” disease conditions have generally declined, although there were peaks in 1998

- 1999 and 2001

- 2002

. Long spined urchins ( Diadema
antillarum ) are herbivores that help keep corals free of algal overgrowth. Observa tions of D. antillarum densities have fluctuated, with highs reported in 2002 and 2005 and a general increasing trend since 1996. There are three species of clionid sponges ( Cliona delitrix

, C. lampa , and C. caribbaea ) monitored by CREMP. These taxa are monitored because they can infest and damage coral colonies. By habitat, clionid area increased between 2002 and 2006 at hardbottom sites. At shallow, offshore, and patch reef sites, the populations have had minor fluctuations in mean clionid area throug h time. In general, the patch reef sites have had higher clionid area than shallow or deep reef sites.

Figure 13

. Number of stations with stony coral disease recorded (Callahan et al. 2007).

In January 2010 Florida experienced one of its coldest 12 -d ay periods on record. Water temperatures were depressed below the lethal limit for corals (~16°C) for four to five days. The coldest temperatures were observed at exchanges between Florida Bay and The Atlantic. The most significant coral mortality

was o bserved at sites closest to shore (F igure 14). Mortality varied by station due to species composition. Some stations which were primarily composed by species like M. annularis complex and

M. cavernosa experienced a greater than 50% reduction in coral cover. In many instances declines in octocoral cover exceeded those of stony corals ( F igure 1 4 ).Nutrient Criteria Technical Support Document Florida Keys

Draft 24 August 2010 Figure 14. Percent cover comparisons between summer 2009 and February 2010 for a) stony corals and b)

oc tocorals at eight stations (CREMP 2010).

Swart et al. (2005) reported temporal and spatial variability in δ 13 C and δ 15 N of the tissues and zooxanthellae of corals from nearshore and offshore reefs over a 2 year period

, from 1995

- 1996. There were no signif icant seasonal variations in the δ 15 N of coral or zooxanthellae at any of the sites, but there was a significant decrease in δ 15 N over the course of the study. The decrease was greater in the
zooxanthellae than the coral tissue and correlated with a decre ase in the concentration of NH 4 + and NO 2 - in the water column. The δ 13 C values of the coral tissues did show seasonal patterns at some, but not all, sites. The authors note that in the literature there is a discrepancy in interpretation of δ 15 N values in marine organisms. In this study, there was no difference in δ 15 N in coral tissues and zooxanthellae from nearshore and offshore environments. Assuming that the δ 15 N can be considered an indicator of anthropogenic influence, t hese results suggest that th e Florida reefs are not affected by anthropogenic
sources of N. Similar to the N results, they also found no differences in δ 13 C between the inner and
outer reefs.
Furman and Heck (2008) tested the single and interactive effects of the urchin ( Diadema ant illaru m) grazing and effects of experimental nutrient enrichment on macroalgal community dynamics at a site in the lower Keys in the summer of 2004. The objective of their study was to assess the relative importance of top

- down and bottom

- up processes in controlling macroalgal recruitment in a sub

tropical coral reef system. Although algal succession differed from what had been expected, the results demonstrated the important role of herbivory in controlling benthic primary production, especially
related to nutrient enrichment. Results of fish counts and grazing assays suggested that piscine grazing was dominant as opposed to the expected echinoderm grazing. Total fish abundance and herbivore density was consistently greater at enriched plots, leading to no significant increase in algal biomass at
the nutrient enriched sites.

Nutrient enrichment is considered to be one of several factors potentially contributing to coral declines. Lirman and Fong (2007) evaluated whether proximity to shore and connection s to coastal bays (two measures of potential land

- based sources of disturbance) adversely influenced coral community and population structure, and the abundance, distribution, and condition of corals within the Florida ReefNutrient Criteria Technical Support Document Florida Keys

Draft 25 August 2010 Tract. They found that spatial patterns in coral indicators do not appear to be directly related to water quality gradients influenced by land

- based sources of disturbance. Szmant (2002) evaluated reports based on the supporting evidence for nutrient enrichment and other factors that c ould simultaneously affect coral reefs. She proposed that many factors, other than nutrient enrichment, can all be significant causes of coral death and also can cause changes in algal cover. These factors include: decreased abundance of grazing fishes c aused by over fishing, decreases in grazing urchins caused by disease, grazing preferences of the remaining grazers, lethal temperature stress, sedimentation, coral diseases, and outbreaks of coral predators and sea urchins (possibly as secondary effects of over fishing). In the Florida Keys, Szmant (2002) found no reports to indicate that there is a clear connection between present water quality conditions and coral health that explain the declines in the reefs. In fact, higher algal cover and lower adul t coral cover and recruitment has been observed on outer reefs when compared with those reefs closer to shore (Chiappone 1996 and Miller et al. 2000 in Szmant 2002). Note that the nearshore reefs are directly adjacent to potential sources of land

- based nu trients, temperature stress, and sedimentation. Since nearshore reefs actually fared better than their offshore counterparts, this also suggests that land based sources of pollution, including nutrients, are not directly responsible for coral declines.

Additional Biological Resources

There are recreational, commercial, and “headboat” fisheries in the Florida Keys

, with fishers including both residents and visitors (Donahue et al. 2008). The Keys have been heavily fished

, and fishing pressure has greatly increased due to augmented fishing power per vessel and a much larger recreational fishery (Ault et al. 1997). Estimated fishery exploitation rates suggest that many of the

F lorida Keys reef fish stocks are overfished according to definitions for U.S. fisheries

, and results show the classic pattern of serial overfishing where more vulnerable species are progressively depleted. D ata from Ault et al. ( 1997) also suggest that the biomass composition and abundance of the reef fish community may have c hanged over the past several decades. In 1985
, fisheries for conch ( Strombas gigas ) and Goliath and Nassau groupers were closed. In response to overfishing, the FKNMS established a series of Sanctuary Preservation Areas (SPAs) in 1997

.

Bohnsack et al. (2004) reported t rends in reef fish landings from 1981 to 1992 for the Florida Keys

. Depending on the year, recreational landings comprised between 40 % and 66% of total landings. Reef fish accounted for 58% of total fish landings, 69% of recreational landings

, and 16% of commercial landings. Commercial landings were dominated by invertebrates (spiny lobster, shrimp

, and stone crabs), which comprised 63% of total landings.

The Florida Fish and Wildlife Conservation Commission (FWC) conducts visual cens uses between April and October to monitor finfish populations along the Atlantic margin of the Florida Keys in the FKNMS (Donahue et al. 2008) . The goal is to evaluate the relative abundance, size structure

, and habitat utilization of the reef fish specie s that comprise local, commercial

, and r ecreational fisheries ( Figure 15;
T able 5 ).

The FWC began a spiny lobster monitoring program in 1997 to test the effectiveness of no

- take zones (Donahue et al. 2008). Since protection, mean lobster size in reserves has been larger than legal size,Nutrient Criteria Technical Support Document Florida Keys

Draft 26 August 2010 but in exploited areas it has remained below the legal limit most of the time . In most years, the abundance of lobsters declined in both reserves and exploited areas during the open season, but the
declines were lower in the reserves. The decline in abundance inside reserves during the open season indicates that the reserves are too small to adequately protect the lobsters from harvest.

The FWC also monitors the rec overy of the queen conch population (Donahue et al. 2008). Since the fishery was closed in 1985

, there have been signs of recovery.

Figure 15 . Mean fish density by year (2000

– 06) as recorded during visual surveys in the Florida Keys (Donahue et
al. 2 008).

Table 5

. Catch statistics for the 15 more abundant reef fish species observed during the Florida Keys visual sampling, 1999

– 2006.

Note: Percent (%) is the percentage of the total observations represented by that species; percent occurrence (% Occur) is the percentage of samples in which the species was observed; CV is the coefficient of variation. Taxa are ranked in o rder of decreasing mean density ( reference in Donahue et al. 2008).Nutrient Criteria Technical Support Document Florida Keys

Draft 27 August 2010 

### Water Quality Studies

Inshore

- to

- offshore trends have been observed in many investigations of water quality in the Keys (e.g. Lapointe and Clark 1992; Boyer and Jones 2002; Boyer and Briceño 200 9)

. Lapointe and Clark (1992) characterized nutrient concentrations at 30 sites along a gradient from the watershed

- coastal zone to offshore regions, including sites in Florida Bay and along the reef tract. They observed elevated ammonia (NH 4 + ), nitrate (NO 3 - ), and particulate nitrogen (PN) concentrations in canal and seagrass meadows compared with patch and bank reef stations. Soluble reactive phosphorus (SRP) and particulate phosphorus (PP) concentrations were significantly higher in canal systems compared with seagrass, patch reef, and bank reef stations. Chlorophyll a was also higher in nearshore canal a nd seagrass systems compared with reef stations.

Boyer and Jones (2002) also reported declining inshore

- to

- offshore trends for NO 3 - , NH 4 + , TOC, total organic nitrogen (TON), and turbidity. The water quality sampling was conducted quarterly at over 200

s tations in the FKNMS and Shelf, and was conducted monthly in Florida Bay, Biscayne Bay, and the southwest coast mangrove estuaries. Sampling stations were stratified according to depth, geography, distance from shore, proximity to tidal passes, and influe nce of shelf waters . In the Lower Keys, inorganic N and TP were elevated in the Backcountry area. TP concentrations in the Lower Keys decreased with distance offshore, but increased along transects in the Upper Keys (Boyer and Jones 2002). The Upper Key s generally had lower nutrient concentrations than the Lower and Middle Keys. Ambient water quality in the Lower Keys and Marquesas is most influenced by the Shelf; the Middle Keys is influenced by the Shelf and Florida Bay; the Backcountry is influenced by internal nutrient sources; and the Upper Keys water quality is influenced by intrusion of the Florida Current (Boyer and Jones 2002).Nutrient Criteria Technical Support Document Florida Keys

Draft 28 August 2010 Water quality monitoring in the Florida Keys is collected as part of the larger Southeast Environmental
Research Cent er (SERC) water quality monitoring network in south Florida. Stations in the FKNMS are sampled quarterly and samples have been collected since it was established in 1995. The i nformation
below is selected from the 2008 Annual Report of the Water Quality Monitoring Project for the FKNMS water quality protection program (Boyer and Briceño 200 9). The report includes information on data
collected between March 1995 and December 2008

. Figure 16 shows the study area and subregions

, and Figure 17 shows the location of the monitoring sites (Boyer and Briceño 200 9 ). The 2008 report includes data from 50 quarterly sampling events at 154 stations within the FKNMS.

Figure 1 6 . Map of study area (Boyer 2010).

Figure 18 shows the distribution of sal inity across the region based on median salinities for each station

. The major freshwater sources to the region are the Shark River/Slough system on the southwest coast of the Florida peninsula and the Taylor Slough/C

- 111 Basin in eastern Florida Bay. Southerly currents along
the southwest coast and Shelf move water through the Keys passes and may impact the reef tract.

The distribution of dissolved NO 3 - and NH 4 + are very different than that for salinity (Figure 19 ) , with
hi ghest values in nearshore are as. This implies that factors other than mixing of freshwater affect their distributions, such a s phytoplankton and seagrass uptake as well as N 2 fixation and benthic
remineralization.

In contrast, TP distributions are very similar to salinity patterns on the west coast (Figure s 17 and 20 ). This implies that the source of P on the Shelf is partly terrestrial and partly from the southward transport of coastal waters from above Cape Romano. It is important to note that the chlorophyll a concentrations are tightly coupled to TP availability (Figure s 20 and 2 1 ).Nutrient Criteria Technical Support Document Florida Keys

Draft 29 August 2010 Figure 1 7 . Florida International University (FIU) Southeast Environmental Research Center (SERC) Water Quality Monitoring Network. Stations in red are sampled as part of the FKNMS monitoring program (Boyer and Briceño 2009).

Table 6 provides median values for water quality parameters collected as part of the monitoring program (Boyer and Briceño 2009). TN values ranged from 0.0546 to 0.692 and 0.044 to 1.358 mg L -1 for surface and bottom samp les respectively. TP values ranged from 0.003 to 0.0441 and 0.0027 to 0.177 mg L -1 for surface and bottom samples respectively. Median values were similar for surface and bottom values for both TN and TP. Chlorophyll a ranged from 0 to 9. 18 μg L -1 with a median of 0.19 μg L -1

. Surface and bottom DO concentrations were similar with median values of 5.26 and 4.88 respectively. -83.0 -82.5 -82.0 -81.5 -81.0 -80.5 24.5 25.0 25.5 26.0 26.5

Miami

Gulf of Mexico

Florida Straits Southeast Environmental Research Center Florida International University

Funded By SFWMD and EPA Water Quality Monitoring Network

Quicksands Dry Tortugas Marquesas SW Florida Shelf Pine Island

Sound

Marco Island

Florida Bay Biscayne Bay

Whitewater Bay Ten Thousand Islands

EvergladesNutrient Criteria Technical Support Document Florida Keys

Draft 30 August 2010 Table 6. Water quality variables measured in the FKNMS, March 1995

– Decem ber 2008 (Boyer and Briceño
2009 ).

1 mg L -1 = Milligrams per liter NTU = Nephelometric Turbidity Unit SU = Standard Unit
**μ** g L -1 = Micrograms per liter Variable 1 Depth Median Minimum Maximum

NO 3 - (mg L - 1 ) Surface 0.00252 0 0.03066

NO 3 - (mg L - 1 ) Bottom 0.00168 0 0.02576

NO 2 - (mg L - 1 ) Surface 0.00056 0 0.00462

NO 2 - (mg L - 1 ) Bottom 0.00042 0 0.00266

NH 4 + (mg L - 1 ) Surface 0.00686 0.00042 0.10598

NH 4 + (mg L - 1 ) Bottom 0.0042 0.00014 0.04676 TN (mg L - 1 ) Surface 0.1435 0.0546 0.69188 TN (mg L - 1 ) Bottom 0.1211 0.04438 1.35772 TON (mg L - 1 ) Surface 0.12362 0 0.68754 TON (mg L - 1 ) Bottom 0.1106 0.02688 1.3566 TP (mg L - 1 ) Surface 0.0066 0.003 0.0441 TP (mg L - 1 ) Bottom 0.006 0.0027 0.0177 SRP (mg L - 1 ) Surface 0.0009

- 0.0003 0.0234 SRP (mg L - 1 ) Bottom 0.0009

- 0.0009 0.0204 Turbidity (NTU) Surface 0.51 0 10.73 Turbidity (NTU) Bottom 0.37 0.01 5.78 Salinity (SU) Surface 36.25 23.49 47.3 Salinity (SU) Bottom 36.37 33.68 38.9
Temperature ( °C ) Surface 26.96 18.87 33.2
Temperature ( °C ) Bottom 26.75 18.8 33 DO (mg L - 1 ) Surface 5.26 2.07 9.5 DO (mg L - 1 ) Bottom 4.88 2.97 8 DO Saturation (%) Surface 80.05 0 134.7 DO Saturation (%) Bottom 73.34 0 119.3 Chlorophyll a (μg L - 1 ) Surface 0.19 0 9.18Nutrient Criteria Technical Support Document Florida Keys

Draft 31 August 2010 Figure 1 8 . Median salinity, 1995

– 2009 (Boyer and Briceño 2009).

Figure 1 9 . Dissolve d inorganic nitrogen (micromolar [μM]) median, 1995

– 2007 (Boyer and Briceño 2009).Nutrient Criteria Technical Support Document Florida Keys

Draft 32 August 2010 Figure 20 . TP (μM) median, 1995

– 2007 (Boyer and Briceño 2009).

Figure 2 1 . Chlorophyll a (μg L -1 ) median, 1995

– 2007 (Boyer and Briceño 2009).Nutrient Criteria Technical Support Document Florida Keys

Draft 33 August 2010 The monitoring project resulted in s everal important findings

. First, the study documented elevated
nitrate in the in sho re waters of the Keys ( Figure 22 )

. This result was evident from the first sampling
event in 1995 and continues to be a characteristic of the ecosystem. Inte restingly, this gradient was not observed in a comparison transect from the Tortugas (no human impact). This type of distribution implies an inshore source that is diluted by low -n utrient Atlantic Ocean waters. The p resence of a similar gradient in TOC a nd decreased variability in salinity from land to reef also support this concept.
There were no trends in either TP or chlorophyll a with distance from land.

Second, the study showed that the highest chlorophyll a concentrations are seen on the Shelf

, with a
strong gradient towards the M arquesas and Tortugas ( Figure 21 ). This is due to the higher TP
concentrations on the Shelf as a result of the southerly advection of water along the coast.

Figure 2 2 . Dissolved inorganic nitrogen (μM) (Boyer and B riceño 2009).



### Waters on the 303(d) List

The halo zone waters of the Keys were listed as impaired on the 1998 303(d) list, however they have yet to be verified as impaired under the Impaired Waters Rule (IWR), pending a decision by EPA on the

FKRAD. For t he purposes of the FKRAD, the halo zone, or bubble WBIDS, waters are defined as extending from the coastline out to 500 m. Nearshore waters extend from 500 m to 12,100 m and farfield waters, which are assumed to have water quality controlled by outside in fluences as opposed to land based nutrient sources, are beyond the 12,100 m. Figure 23 shows a map of the Keys with the WBIDS and regions identified.

In addition to nutrients, waters in the Florida Keys are listed as impaired for several other param eters: mercury (in fish tissue), bacteria, and fecal coliform bacteria ( Table 7 ). Mercury impairments are not related to anthropogenic nutrient inputs. The relationship between bacteria and anthropogenic nutrients is more complex, because although poten tial sources of bacteria may also be sources of nutrients, the presence of fecal coliform or enterococci bacteria does not necessarily indicate the presence of anthropogenic nutrients.Nutrient Criteria Technical Support Document Florida Keys

Draft 34 August 2010 Table 7. Verified impairments in the Florida Keys basin.

Basin Group Name Planning Unit Waterbody ID (WBID) Water Segment Name Waterbody Type Waterbody Class 1 Parameters Assessed Using the 2001 Impaired Surface Waters Rule (IWR) Concentration Causing Impairment 2 Priority for TMDL Development 3 Comments (# Exceedances/# Samples) pp = Planning Period vp = Verified Period 4

Florida Keys Upper Keys 6005EB JOHN PENNEKAMP STATE PARK BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2002, 2003, 2004, 2005, and 2006.

Florida Keys Lower Keys 8073C SIMONTON STREET BEACH (KEY WEST) BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2004, 2005, and 2006.

Florida Keys Lower Keys 8073E SOUTH BEACH (KEY WEST) BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2002, 2003, 2004, 2005, and 2006.

Florida Keys Lower Keys 8073F HIGGS BEACH BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2001, 2002, 2003, 2004, 2005, and 2006.

Florida Keys Lower Keys 8073G REST BEACH (KEY WEST) BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2001. (No data available for 2003, 2004, 2005, and 2006.)

Florida Keys Lower Keys 8073H SMATHERS BEACH BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2002, 2003, 2005, and 2006.

Florida Keys Middle Keys 8076A VETERAN'S BEACH BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2004 and 2005

Florida Keys Upper Keys 8078A HARRY HARRIS COUNTY PARK BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2002, 2004, 2005, and 2006.

Florida Keys Upper Keys 8078B ISLAMORADA LIBRARY BEACH BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2004, 2005, and 2006.

Florida Keys Upper Keys 8078C FOUNDER BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2002, 2004, 2005, and 2006.

Florida Keys Lower Keys 8080A BAHIA HONDA SANDSPUR BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2005 and 2006

Florida Keys Lower Keys 8080B BAHIA HONDA OCEANSIDE BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2001, 2005, and 2006.

Florida Keys Middle Keys 8081A COCO PLUM BEACH BEACH 3M Bacteria Beach Advisories > 21 days/yr High Beach advisories > 21 days/yr in 2001, 2004, 2005, and 2006. Florida Keys Upper Keys 6009 PLANTATION KEY COASTAL 3M Copper > 3.7 μg/L Medium PP = No Data; VP = 21 / 29Nutrient Criteria Technical Support Document Florida Keys

Draft 35 August 2010

Basin Group Name Planning Unit Waterbody ID (WBID) Water Segment Name Waterbody Type Waterbody Class 1 Parameters Assessed Using the 2001 Impaired Surface Waters Rule (IWR) Concentration Causing Impairment 2 Priority for TMDL Development 3 Comments (# Exceedances/# Samples) pp = Planning Period vp = Verified Period 4
Florida Keys Upper Keys 6019 LOWER MATECUMBE KEY COASTAL 3M Copper > 3.7 μg/L Medium PP = No Data; VP = 8 / 13

Florida Keys Lower Keys 8073 KEY WEST AND OUTLYING ISLANDS COASTAL 3M Fecal Coliform > 400 colonies/100 ml Low pp = 325/2262; vp = 362/3036 Florida Keys Upper Keys 6006A SOUTH KEY LARGO COASTAL 3M Copper > 3.7 μg/L Medium PP = No Data; VP = 42 / 86

Florida Keys Upper Keys 6006C NORTH KEY LARGO COASTAL 3M Copper > 3.7 μg/L Medium PP = No Data; VP = 5 / 8. Assessment based on Period of Record data Florida Keys Middle Keys 6011A VACA KEY COASTAL 3M Copper > 3.7 μg/L Medium PP = No Data; VP = 19 / 47 Florida Keys Lower Keys 6012A BIG PINE KEY COASTAL 3M Copper > 3.7 μg/L Medium PP = No Data; VP = 8 / 21 Florida Keys Lower Keys 6013C CUDJOE KEY COASTAL 3M Copper > 3.7 μg/L Medium PP = No Data; VP = 5 / 19

Florida Keys Lower Keys 6014A KEY WEST COASTAL 3M Fecal Coliform > 400 colonies/100 ml Low pp = 418/2256; vp = 459/2573 Florida Keys Lower Keys 6014A KEY WEST COASTAL 3M Copper > 3.7 μg/L Medium PP = No Data; VP = 9 / 31 Florida Keys Lower Keys 6014B STOCK ISLAND COASTAL 3M Copper > 3.7 μg/L Medium PP = No Data; VP = 7 / 14Nutrient Criteria Technical Support Document Florida Keys

Draft 36 August 2010 Figure 23. Map of the Florida Keys with WBIDS and regions (north, central, southcentral, and southern) identified (FDEP 2008 a ).Nutrient Criteria Technical Support Document Florida Keys

Draft 37 August 2010 Figure 2 4

. WBID models in the Florida Keys (McClelland 2010).



### Numeric Nutrient Criteria Recommendations

FDEP ’s evaluation of the biological resources of the Florida K eys indicates that the waters in the
nearshore zone support a healthy well

- balanced community, are attai ning the designated use, and have
not shown adverse effects from nutrient enrichment in the near shore area ( state waters beyond 500 m). Although there have been changes in some communities (e.g., coral loss) ( Table 1 ), evidence suggests that causes other than nutrients are responsible for the responses. Additionally, long term monitoring
of water quality data indicates consistently low water column nutrient concentrations over time

. For the halo zone area, however, current nutrient conditions in the canals may not be protective of canals in the Keys . While nutrient criteria for the canals and halo zone still need to be determined, FDEP supports the nutrient load reductions proposed in the FKRAD in order to improve water quality in the
halo zone and help ensure that criteria are met in nearshore

. FDEP is considering two methods for establishing numeric nutrient criteria in the Keys. The first consists of adopting the criteria established in the FKRAD, which are based on improvin g water quality in the inshore halo zone to modeled targets (FDEP 2008a). The second approach is to subdi vide the nearshore waters ( state waters beyond 500 m ) into zones of similar water quality and establish criteria to maintain the current nutrient data distributions, which would continue to support the existing healthy condition.Nutrient Criteria Technical Support Document Florida Keys

Draft 38 August 2010 FKRAD recommendations

The FKRAD use d two approaches to determine their proposed nutrient targets. One set of target s were developed based on an insignificant increase in natural background TN and TP levels at 500 m from
shore

. An increase of 10 μg l -1 TN or 2 μg l -1 TP was co nsidered an insignificant increase at 500 m from
the shore

. Natural back ground is the predicted model result in the Halo Zone with all of the urban land uses changed to natural conditions ( Figure 24 )

. The model is described in more detail in the FKRAD (F DEP 2008 a ). According to the model, the targets , which FDEP interprets as long term averages, are defined as follows for each area of the Keys ( Tables 8

- 11 ) :

Table 8. Natural background conditions (modeled) and water quality targ ets for the northern Keys (FDEP
2008 a ).

Table 9 . Natural background conditions (modeled) and water quality targets for the central Ke ys (F D EP 2008 a ).Nutrient Criteria Technical Support Document Florida Keys

Draft 39 August 2010 Table 10 . Natural background conditions (modeled) and water quality target s for the south

- central Keys (FDEP
2008 a ).

Table 11 . Natural background conditions (modeled) and water quality tar gets for the southern Keys (FDEP
2008 a ).

The second approach outline d in the FKRAD sets the target nutrient concentrations at the concentrations measured during the 1985 design ation as an OFW. Data from the 1985 designation are provided below – the data and ranges represent nutrient thresholds (FDEP 2008 a).Nutrient Criteria Technical Support Document Florida Keys

Draft 40 August 2010 Table 12. 1985 F DEP OFW water quality data (FDEP 2008 a ).

For comparison, Table 13 provides the range and means of the modeled targets for both TN and TP.
Minimum and maximum values are the modeled values for the individual bubble WBIDs and the average values are the mean of modeled WBID criteria for either the bayside (N) or Oceanside (S) of the Keys. The modeled criteria and the OFW values for bayside TN are comparable, however the modeled maximum values for TN for the oceanside WBIDs are lower and result in a lower average value. For TP, the range of the modeled values is much les s than range of the OFW values and the average of the modeled targets are lower for both bayside and oceanside areas. FDEP does not suggest using the OFW numbers as targets for water quality criteria because the values are based on a limited number of

sa mples taken during a short sampling period. The OFW values are also considerably higher than the modeled recommendations outlined in the FKRAD as well as current data on Florida Keys water quality.

Table 13. Range and means of modeled TN and TP targets f or bayside and oceanside bubble WBIDs (FKRAD 2008).

Modeled water quality targets TN μg l - 1 TP μg l - 1 Average Minimum Maximum Average Minimum Maximum Bayside 353 179 764 10.9 8 13 Oceanside 133 123 142 7.7 7 8

FDEP Nutrient Criteria Approach

The second approach to setting nu meric nutrient criteria is to use water quality data collected by FIU SERC as part of the FKNMS water quality monitoring network to establish nutrient criteria that would
maintain nutrients at the current concentrations that ar e fully protective of aquatic life. Under this approach, TN and TP criteria wo uld be established for sub

- basins having similar water quality outside of
the 500 m limit of the FKRAD criteria.

Regionalizatio n

FIU has utilized the data collected as part of their Coastal Water Quality Monitoring Network initiated in 1992 to spatially aggregate monitoring sites located in south Florida based on similar water quality characteristics (Boyer and Briceño 2008). Based on the unique water quality and geologic chara cteristics observed in south Florida, Everglades National Park (ENP) and Florida International University (FIU) haveNutrient Criteria Technical Support Document Florida Keys

Draft 41 August 2010 proposed that the estuarine and coastal waters of south Florida be divided into sub

- basins for the purpose of deriving nutrient criteria. On behalf of ENP, FIU has recently completed an extensive statistical characterization of coastal waters from Biscayne Bay to Dry Tortugas to Pine Island Sound. The recent analysis was similar to the earlier spatial regionalization method used by FIU, but utilized a longer period of record and a modified set of parameters. The analysis used a combination of Principal Component Analysis and Hierarchical Clustering of multiple (from 8 to 13) parameters, produced a division of the bays as shown in the figure and table below. More detail concerning the analysis conducted by Henry Briceño, Joe Boyer, and Peter Harlem from FIU can be found in Appendix A. Additionally, the GIS layers with information on the sub

- basins as well as FIU’s working files with data

an d statistical analysis are available at a FIU’s ftp site provided earlier.

This regionalization scheme will be the basis for proposing numeric criteria for each sub

- basin. A final step in the process will be to evaluate the similarity of the derived crite ria with the purpose of combining sub

- basins with similar criteria (i.e., criteria that are not statistically different) for total phosphorus, total nitrogen, and chlorophyll

- a.

On the basis of the statistical analysis performed, the south Florida bays and coastal waters, including those of the Florida Keys, wer e divided as detailed in Table 14 and illustrated in Figure 2 5

.
Table 14. Proposed regionalization for the Florida Keys.

Sub

- Basin Map Code Sub

- Basin Name

MAR Marquesas

BACK Back Country

BAY Bayside

DRTO Dry Tortugas

OCEAN OceansideNutrient Criteria Technical Support Document Florida Keys

Draft 42 August 2010 Figure 25

. Proposed estuarine and coastal nutrient criteria sub

- basins for South Florida.Nutrient Criteria Technical Support Document Florida Keys

Draft 43 August 2010 Proposed Numeric Nutrient Criteria

Methodology

For consistent application and for providing an appropriate level of protection, water quality criteria need to include magnitude, frequency, and duration components. The magnitude is a measure of how much of a pollutant may be present in the water without an unacceptable adverse effect. Duration is a measure of how long the pollutant may be above the magnitude, and frequency relates to how often the magnitude may be exceeded without adverse effects. It is preferred to derive the magnitude component of a criterion through a cause

- effect relationship (such as those measured through toxicity testing). The magnitude would then be set at a level that would protect a majority of the sensitive aquatic organisms inhabiting the system. Absent a demonstrated ca use

- effect relationship, the magnitude may be set at a level designed to maintain the current data distribution, accounting for natural temporal variability, when the current conditions are protective of the designated uses of the waterbody. Since a crite rion derived based on the existing data distribution has no direct link to any observed cause and effect relationship, it is assumed that maintaining the current data distribution will preserve the uses associated with that distribution.

The frequency an d duration components of the criteria are best established as additional descriptors of
the reference condition data distribution. Specifically, these components should be part of a statistical test designed to determine whether the long

- term distribution of data has shifted upward ( or in some cases, downward) from the reference distribution. This test would then be used to determine whether future monitoring data are consistent with the magnitude (long

- term average) defined by the reference
dataset. It is critical to account for the natural variability surrounding the magnitude expression and to
control for statistical errors.

The derivation of the magnitude, frequency and duration components of the numeric nutrient criteria
for the Florida Keys is de scribed briefly below. More details concerning the statistical approaches used can be found in the document “Overview of FDEP Approaches for Nutrient Criteria Development in Marine Waters” (FDEP 2010).

Magnitude

The magnitude component can be set at a variety of values based on the frequency and duration that will be used to determine compliance. For the “healthy existing conditions” approach, FDEP established the magnitude at: a) an adjusted long

- term central t endency (geometric mean) of the distribution, expressed as a long

- term geometric mean never to be exceeded; and b) an annual geometric mean, not
to be exceeded more than two times over a five - year period. The long

- term average condition was adjusted to a level that represents an insignificant increase from the baseline. Allowing for an insignificant increase accounts for uncertainty in the estimate of the mean and partially addresses the fact that the reference based approach fails to identify a threshol d of imbalance, and thus is highly prone to excessive Type I error. For the purpose of antidegradation evaluations, EPA has established that a ten percent change in a water quality parameter represents an insignificant departure from the
historical condit ion, known as a de minimus change (US Sixth Circuit Court 2008). Therefore, the long

-Nutrient Criteria Technical Support Document Florida Keys

Draft 44 August 2010 term geometric mean limit was derived to allow for up to a ten percent increase in the long

- term geometric mean, which was calculated as the geometric mean of the annual geometric means of the long

- term dataset for each segment of the waterbody.

Because it is not always practical to assess compliance with the criteria on the same long

- term basis, FDEP also developed criteria expressed as an annual geometric mean so that estuaries could be assessed
on an annual basis. It should be noted that the duration and frequency components of the criteria must be linked to the response timeframe of the sensitive endpoint. Short

- term averaging periods (e.g., 1 to 30 days) might be app ropriate for nutrient criteria where a sufficiently robust cause

- effect relationship has demonstrated that a eutrophic response occurs over such timeframes. If however, such a short

term response cannot be demonstrated, or there is no indicati on of use im pairment, longer averaging periods should be used.

Since the duration and frequency components of the criteria must be consistent with the derivation of the magnitude component, the long

- term geometric mean target cannot simply be applied as an annual

mean. Doing so would result in an unacceptability hig h Type I failure rate (identifying a healthy system as being impaired) since approximately 50 percent of the individual yearly means are expected to be above the long

- term mean. Therefore, the long

- term target must be adjusted to allow for the application to a shorter duration with an acceptable Type I error rate of no more than a 10 percent.

An annual criterion with an approximate 10 percent Type I error rate for a given frequency was derived by appropriately accounting for the annual variability above th e mean. This annual target concentration was derived as an upper percentile of the distribution of the annual geometric mean concentrations. Previous proposals by EPA have utilized three

- year assessment periods to express the duration nutrient
criteria c omponents. Although it is possible to construct a test that achieves the 10 percent Type I error rate target over a 3

- year period, a slightly longer period (5 years) will provide better control for Type II error and will more fully capture climatic cycle s ( e.g ., El Niño, L a Niñ a), which tend to be longer than three years in Florida (and may actually be on a multi

- decadal scale). Furthermore, a five year period is more consistent with both the State’s five year 303(d) assessment and NPDES permit renewal c ycles.

Given a five year a ssessment period, FDEP derived criteria expressed as an annual geometric mean by using the 75 th percentile of the annual geometric means from the long

- term dataset. FDEP demonstrated that setting the criteria at this percentile results in a magnitude that, when expressed as an annual geometric mean not to be exceeded more than twice during a five

- year period, will achieve the targeted 10 percent error rate

. The magnitude component of the criteria (not to be exceeded more
than twi ce in a 5 year period) was established to allow for two separate assessments:

**•** As an annual geometric mean for a network of stations in a specified segment of the waterbody;
and

**•** As an annual geometric mean for a single station in a given segment.

The two expressions of magnitude differ in the handling of within

- segment spatial variability. The network average magnitude was calculated based on the distribution of spatially averaged annualNutrient Criteria Technical Support Document Florida Keys

Draft 45 August 2010 geometric means, while the single site magnitude was calculated usi ng the distribution of station annual geometric means. Use of the network average magnitude is appropriate for assessing overall segment

status. However, a network average is only representative of overall segment status if it is relatively homogeneous. I f the segment is not well mixed, is very large, or contains localized nutrient sources, then there is a potential that isolated areas of enrichment may be masked in the network spatial

average. Therefore, the single station annual geometric mean has th e benefit of assessing localized enrichment patterns. DEP has not decided whether both expressions of magnitude are needed in all cases, and we are seeking additional feedback from local experts and stakeholders.

Summary of the Proposed Criteria

FDEP prop oses three sets of potential criteria: a) a long

- term geometric mean concentration; b) an annual geometric mean of values from a network of stations over a given area, not to be exceeded more
than twice in a five

- year period; and c) a n annual geometric me an of values from a single location, not to
be exceeded more than twice in a five

- year period. The proposed long

- term targets for the protection of a healthy, wel l- balanced aquatic community in the Florida Keys, as well the annual limits for each
segment, are provided in Table 15

.Nutrient Criteria Technical Support Document Florida Keys

Draft 46 August 2010 Table 15. Proposed numeric nutrient criteria for all segments of the Florida Keys, including TP, TN, and chlorophyll a. For compliance purposes, the long term geometric mean shall not exceed the long term limit nor
sha ll the average of all stations in a segment exceed the network average more than twice in a 5 year period. The last column shows the value which single station shall not exceed, by segment, more than twice in a 5 year period.

Total Phosphorus (μg l -1 )

Segment Existing Long
Term Geometric
Mean Maximum Allowed Long Term Geometric
Mean Annual Geometric Mean for a Network of Stations (2 of 5 year exceeda nce rate) Annual Geometric Mean for a Single Site (2 of 5 year exceedance rate)

Marquesas 6.42 7.06 8.12 8.77
Back Country 8.72 9.59 10.88 11.61
Bayside 7.49 8.24 9.75 10.42
Dry Tortugas 5.86 6.45 7.79 8.26

Oceanside 5.66 6.23 7.33 7.89

Total Nitrogen (μg l -1 )

Segment Existing Long
Term Geometric
Mean Maximum Allowed Long Term Geometric
Mean Annual Geometric Mean for a Network of Stations (2 of 5 year exceeda nce rate) Annual Geometric Mean for a Single Site (2 of 5 year exceedance rate)

Marquesas 14 3 157 196 209
Back Country 196 21 6 247 269
Bayside 19 6 216 260 279
Dry Tortugas 129 142 184 194

Oceanside 14 7 162 186 204

Chlorophyll a (μg l -1 )

Segment Existing Long
Term Geometric
Mean Maximum Allowed Long Term Geometric
Mean Annual Geometric Mean for a Network of Stations (2 of 5 year exceeda nce rate) Annual Geometric Mean for a Single Site (2 of 5 year exceedance rate)

Marquesas 0.35 0.39 0.50 0.63
Back Country 0.36 0.39 0.50 0.65
Bayside 0.26 0.29 0.37 0.47
Dry Tortugas 0.21 0.23 0.31 0.37

Oceanside 0.19 0.21 0.28 0.33Nutrient Criteria Technical Support Document Florida Keys

Draft 47 August 2010 Comparison of FKRAD and FDEP approaches

Tables 16 and 1 7 compare the FKRAD targets for the halo zone with the FDEP proposed criteria for the
nearshore zone for each of the sub

- basins. For both TN and TP, the OFW targets are higher than both the modeled targets and the criteria proposed for the sub

- basin s in the nearshore zone, with the exception of the modeled targets for WBIDs 8N and 9N on the bay

- side of the upper Keys. In most cases, the TP targets in the FKRAD agree with concurrent sub

- basin two out of five year annual limits calculated by FDEP. Th ere are several TN WBID targets on the bay side of the Keys, however, that have considerably higher target concentrations in the FKRAD than those calculated for adjacent sub

- basins by FDEP in Florida Bay. FDEP is seeking input on the proposed approaches

.Nutrient Criteria Technical Support Document Florida Keys

Draft 48 August 2010 Table 16 . Comparison of TN (μg l -1 ) targets for halo zone modeled WBIDs and OFW targets ( from the FKRAD )
with nearshore FDEP criteria proposed for sub

- basins using FIU long

- term water quality data. For maps showing the locations of WBIDs and sub

- basins, see Figures 24 and 25

.

Halo Zone (500 m) targets (FKRAD) Nearshore (500

- 12,100 m) criteria (FDEP and FIU) Modeled bubble WBIDs OFW Proposed criteria by sub

- basin

WBID model ID T arget Target Sub

- basin name Long term limit (2 out of 5 year single site assessment)

1N 179 Bayside 370 Backcountry 216 (269)
2N 205 Bayside 370 Backcountry 216 (269)
3N 215 Bayside 370 Backcountry 216 (269)
4N 221 Bayside 370 Backcountry 216 (269)
5N 225 Bayside 370 Bayside 216 (279)
6N 248 Bayside 370 Bayside 216 (279)
7N 399 Bayside 370 Bayside 216 (279)
8N 764 Bayside 370 West Florida Bay* 331 (421 )
9N 739 Bayside 370 South Florida Bay* 535 (694 )
10N 334 Bayside 370 East Central Florida Bay* 568 (696 )

1S 142 Oceanside 288 Ocean 162 (204)
2S 135 Oceanside 288 Ocean 162 (204)
3S 138 Oceanside 288 Ocean 162 (204)
4S 141 Oceanside 288 Ocean 162 (204)
5S 135 Oceanside 288 Ocean 162 (204)
6S 135 Oceanside 288 Ocean 162 (204)
7S 125 Oceanside 288 Ocean 162 (204)
8S 124 Oceanside 288 Ocean 162 (204)
9S 123 Oceanside 288 Ocean 162 (204)
10S 128 Oceanside 288 Ocean 162 (204) Marquesas 157 (209 ) Dry Tortugas 142 (194 )

*Three sub

- basins from Florida Bay are included for comparison because they are adjacent to halo zone WBIDs on the bay

- side of the upper Keys.Nutrient Criteria Technical Support Document Florida Keys

Draft 49 August 2010 Table 1 7 . Comparison of TP (μg l -1 ) targets for halo zone modeled WBIDs and OFW targets (from the FKRAD) with nearshore criteria proposed for sub

- basins using FIU long

- term water quality data. For maps showing the locations of WBIDs and sub

- basins, see Figures 2 4 and 25

.

Halo Zone (500 m) targets (FKRAD) Nearshore (500

- 12,100 m) criteria (FDEP and FIU) Modeled bubble WBIDs OFW Proposed criteria by sub

- basin

WBID model ID T arget Location Target Sub

- basin name Long term limit (2 out of 5 year assessment)

1N 11 Bayside 14 Backcountry 9.59 (11.6 1)
2N 12 Bayside 14 Backcountry 9.59 (11.61)
3N 12 Bayside 14 Backcountry 9.59 (11.61)
4N 12 Bayside 14 Backcountry 9.59 (11.61)
5N 10 Bayside 14 Bayside 8.2 4 (10.4 2)
6N 10 Bayside 14 Bayside 8.24 (10.42)
7N 13 Bayside 14 Bayside 8.24 (10.42)
8N 11 Bayside 14 West Florida Bay* 13.22 (17.63)
9N 10 Bayside 14 South Florida Bay* 7.65 (9.83)
10N 8 Bayside 14 East Central Florida Bay* 6.48 (7.89)

1S 8 Oceanside 15 Ocean 6.2 3 (7.89 )
2S 8 Oceanside 15 Ocean 6.23 (7.89)
3S 8 Oceanside 15 Ocean 6.23 (7.89)
4S 7 Oceanside 15 Ocean 6.23 (7.89)
5S 8 Oceanside 15 Ocean 6.23 (7.89)
6S 7 Oceanside 15 Ocean 6.23 (7.89)
7S 7 Oceanside 15 Ocean 6.23 (7.89)
8S 8 Oceanside 15 Ocean 6.23 (7.89)
9S 8 Oceanside 15 Ocean 6.23 (7.89)
10S 8 Oceanside 15 Ocean 6.23 (7.89) Marquesas 7.06 (8.77 ) Dry Tortugas 6.4 5 (8.26 )

*Three sub

- basins from Florida Bay are included for comparison because they are adjacent to halo zone WBIDs on the bay

- side of the upper Keys.Nutrient Criteria Technical Support Document Florida Keys

Draft 50 August 2010 

### References

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– 17.Nutrient Criteria Technical Support Document Florida Keys

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### Appendix A. Permitted facilities and landfills in the Florida Keys basin by planning unit (FDEP 2008b).Nutrient Criteria Technical Support Document Florida Keys

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