# S tate o f F lorida

N umeric N utrient C riteria

D evelopment P lan

**March 200**  **9**

Prepared by:

Bureau of Assessment and Restoration Support

Division of Environmental Assessment and Restoration Florida Department of Environmental Protection Tallahassee, FLState of Florida Numeric Nutrient Criteria D evelopment Plan March 2009

ii Florida Department of Environmental ProtectionState of Florida Numeric Nutrient Criteria Development Plan March 2009

iii 

## Contents

LIST OF ACRONYMS AND ABBREVIATIONS

................................ ................................ ...... VIII

1. BACKGROUND AND CRITE RIA DEVELOPMENT PROC ESS

................................ ........... 1

1.1 Use of a Technical Advisory Committee

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

1.2 Post

- TAC Rule Development

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

2. NUTRIENT CRITERIA DE VELOPMENT AND IMPLEM ENTATION

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

2.1 EPA Guidance

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

2.2 FDEP’s Approach

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

2.3 Implementation

................................ ................................ ................................ ........ 15

3. TECHNICAL APPROACHES

................................ ................................ ............................. 15

3.1 Initial Investigations

................................ ................................ ................................ 15

3.2 Biological Criteria Development

................................ ................................ ............. 17

3.3 Nutrient Gradient Stream Study

................................ ................................ ............. 17

**3.3.1 Study Objectives** 

**................................ ................................**  **.......................... 18** 

**3.3.2 Study Methodology** 

**................................ ................................**  **...................... 18** 

**3.3.3 Antic**  **ipated Study Outcomes and Statistical Approach**

**............................ 19** 

3.4. Development and Initial Application of the Nutrient Benchmark Distributional Approach

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

**3.4.1 Identification of Candidate Benchmark Sites (LDI)** 

**................................ ....**  **21**

**3.4.2 Additional Benchmark Site Evaluation** 

**................................ .......................**  **23**

**3.4.3 F**  **ield Evaluation of Peninsula Bioregion Benchmark Stream Sites**

**.......... 24** 

**3.4.4 Statistical Outlier Analyses** 

**................................ ................................**  **......... 31** 

**3.4.5 Calculation of Annu**  **al WBID Geometric Mean**

**................................ ...........**  **31**

**3.4.6 Defining Nutrient Limits** 

**................................ ................................**  **............... 31** 

**3.4.7 Ongoing and Future Efforts** 

**................................ ................................**  **........ 32** 

3.5 Stressor Identification Study

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

3.6 Development of the Stream Periphyton Index

................................ ....................... 34

3.7 Downs tream Effects of Nutrients in Selected Florida Rivers/Estuaries (Nutrient Longitudinal Study)

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

**3.7.1 Project Objectives** 

**................................ ................................**  **........................ 36** 

**3.7 .2**  **Project Description**

**................................ ................................**  **...................... 36** 

**3.7.3 Project Outcomes** 

**................................ ................................**  **........................ 37** 

3.8 Nitrate

- Nitrite Analysis in Streams/Spring Runs

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

3.9 Lake Algal and Macrophyte Response

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

3.10 Recreation

- Based Criteria

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

3.11 Appl ication of Benchmark Distributional Approach to Lakes

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

3.12 Approach for Estuaries

................................ ................................ ........................... 41

3.13 Microcystin Round Robin

................................ ................................ ....................... 44

4. RELATION TO STATE US E CLASSIFICATIONS

................................ .............................. 45State of Florida Numeric Nutrient Criteria Development Plan March 2009

iv 5. RELATION TO BIOGEOGR APHIC CLASSIFICATION

................................ ...................... 45

6. DATA SOURCES

................................ ................................ ................................ ............... 46

6.1 Inventory of Existing Data

................................ ................................ ....................... 46

6.2 FDEP’s Ambient Monitoring Program

................................ ................................ .... 46

6.3 Requirements for New Data Collection

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

7. COORDINATION WITH BO RDERING STATES

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

8. PRIORITIZATION OF WA TERS AND SCHEDULE FO R DEVELOPMENT AND

ADOPTION

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

8.1 Lakes and Streams (1 st Priority)

................................ ................................ ............. 48

8.2 Estua ries (2 nd Priority)

................................ ................................ ............................. 49

8.3 Wetlands (3 rd Priority)

................................ ................................ .............................. 4 9

9. FLORIDA’S ONGOING IN VESTMENT IN NUTRIENT CRITERIA DEVELOPMENT

.......... 50

10. PAST, CURRENT, AND F UTURE SCHEDULE FOR N UTRIENT CRITERIA

DEVELOPMENT FOR FLOR IDA’S WATERS

................................ ................................ .... 50

REFERENCES CONSULTED OR CITED

................................ ................................ ................. 56

APPENDICES

................................ ................................ ................................ ........................... 61
Appendix A: FDEP’s Review of EPA’s Recommended Nutrient Criteria for

Streams and Lakes

................................ ................................ ................................ .. 61
Appendix B: Selection of Benchmark Sites (Characterized by Low Levels of Human Disturbance) Using the LDI Index

................................ ............................. 73

Appendix C : Peninsular Benchmark Site Summa ries

................................ ................... 83State of Florida Numeric Nutrient Criteria Development Plan March 2009

v 

## List of Tables

Table 1. EPA

- generated nutrient criteria recommendations for nutrient ecoregions, including all or part of Florida

................................ .................... 4

Table 2. FDEP Nutrient Criteria TAC members

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

Table 3. Summary of regulatory structure and progress towards adopting

nutrient criteria in Florida

................................ ................................ ................ 16

Table 4. Parameters monitored during the peninsula bioregion benchmark

survey

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

Table 5. Recent and planned funding for nutrient criteria devel opment in

Florida

................................ ................................ ................................ ............... 51

Table A

- 1. EPA recommendations for streams using the lower 25 th percentile approach of a dataset of unknown site quality

................................ .............. 63

Table A

- 2. EPA recommendations for lakes/impoundments using the lower

25 th percentile approach of a dataset of unknown site quality

..................... 64

Table A

- 3. Summary of seasonal values ch lorophyll **a** concentrations used by EPA to derive the recommended Ecoregion IX rivers and streams chlorophyll **a** criteria

................................ ................................ ........................ 65

Table A

- 4. Summary of seasonal values chlorophyll **a** concentrations us ed by

EPA to derive the recommended Ecoregion XII rivers and streams chlorophyll **a** criteria

................................ ................................ ........................ 65

Table B

- 1. Comparison of FWCI scores using Fisher’s one

- way multiple comparison test for three se parate species assemblages (diatoms, macrophytes, and macroinvertebrates) for depressional palustrine

wetlands

................................ ................................ ................................ ............ 75State of Florida Numeric Nutrient Criteria Development Plan March 2009

vi 

## List of Figures
Figure 1. Draft aggregations of Level III ecoregions for the national nutrient strategy in Florida

................................ ................................ ............................ 3

Figure 2. Level IV subecoregions for Florida: Small/wadeable streams

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

Figure 3. Level IV subecoregions for Florida lakes

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

Figure 4. Stream bioregions of Florida

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

Figure 5. Plots of SCI versus TP concentrations at sites visited during the peninsula benchmark stream survey

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

Figure 6. Plots of SCI versus TN concentrations at sites visited during the peninsula benchmark s tream survey

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

Figure 7. Plots of percent (A) Bacillariophyta, (B) Cryptophycophyta, and (C) Cyanophycota collected on natural substrates versus site period of record geometric mean TP concen trations

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

Figure 8. Plots of percent (A) Bacillariophyta, (B) Cryptophycophyta, and (C) Cyanophycota collected on natural substrates versus site period of record geometric mean TN concentrat ions

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

Figure 9. Probability of observing LVI value less than 37 in Florida lakes if specified TP concentration is exceeded

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

Figure 10. Probability of observing LVI value less than 37 in Florida lakes if specified TN concentration is exceeded

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

Figure A

- 1. Aggregations of Level III ecoregions for national nutrient strategy

............. 62

Figure A

- 2. Location of sampling stations used by EPA to derive Ecoregion IX

recommended nutrient criteria for rivers and streams and lakes

................. 63

Figure A

- 3. Stream bioregions of Florida

................................ ................................ ........... 67

Figure A

- 4. Cumulative frequency distributions of (A) total phosphorus, (B) total nitrogen, (C) chlorophyll **a** , and (D) tu rbidity in confirmed peninsula bioregion reference streams

................................ .......................... 68

Figure A

- 5. Adverse biomass changes in Suwannee River periphyton related to anthropogenic nitrate

- nitrate levels

................................ ................................ 69

Figure A

- 6. Increases in **Vaucheria** sp. (nuisance algae) in Florida spring runs related to anthropogenic nitrate

- nitrate levels (graph lists TN as axis, but this was predominantly nitrate

- nitrate)

................................ ........... 69

Figure A

- 7. Cumulative frequency distributions of (A) total phosphorus, (B) total nitrogen, and (C) chlorophyll **a** in Florida lakes with healthy aquatic plant communities (LVI ≥ 37)

................................ .............................. 70

Figure B

- 1. Area

- weighted LDI Index versus phosphorus pollutant load in 64 hydrologic units (subwatersheds) of the St. Ma rks River watershed.

.......... 76

Figure B

- 2. Box plot comparison of macroinvertebrate FWCI scores among LDI groups, including Group 1 (LDI = 1.0), Group 2 (1.0 < LDI ≤ 2.0), Group 3 (2.0 < LDI ≤ 3.0), and Group 4 (LDI > 3.0).

................................ ......... 77State of Florida Numeric Nutrient Criteria Development Plan March 2009

vii Figure B

- 3. Box plot comparison of SCI scores and LDI values calculated based on a 100 m buffer area extending 10 km upstream of the sample point

................................ ................................ ................................ ..... 77

Figure B

- 4. Comparison of average number of sensitive stream macroinvertebrate taxa for sites within different LDI groups

....................... 78

Figure B

- 5. Log of lake median chlorophyll **a** concentrations versus LDI

....................... 79State of Florida Numeric Nutrient Criteria Development Plan March 2009

viii 

## List of Acronyms and Abbreviations

AGP Algal Growth Potential

BCG Biological Condition Gradient

BMP Best Management Practice

BMAP Basin Management Action Plan

BioRecon BioReconnaissance

BOD Biochemical Oxygen Demand

CADDIS Causal Analysis/Diagnosis Decision Information System

CWA Clean Water Act

DO Dissolved Oxygen

EPA U.S. Environmental Protection Agency

ERC Environmental Regulation Commission

ETAC Eve rglades Technical Advisory Committee

F.A.C. Florida Administrative Code

FDEP Florida Department of Environmental Protection

FWCI Florida Wetland Condition Index

GED Gulf Ecology Division

GOMA Gulf of Mexico Alliance

IWRM Integrated Water Resource M onitoring

HA Habitat Assessment

HAB Harmful Algal Bloom

HA Habitat Assessment

HDG Human Disturbance Gradient

HUC Hydrologic Unit Code

IRL Indian River Lagoon

IWR Impaired Surface Waters Rule

Km Kilometer

LDI Land Development Intensity

LOPP Lake Okeechobee Protection Plan

LSD Least Significant Difference

LVI Lake Vegetation Index
kg N/ha/yr Kilograms of N itrogen per H ectare per Y ear

m Meter
mg/L Milligrams per L iter
mg/m 3 Milligrams per C ubic M eter

NASQAN National Stream Quality Accountin g Network

NAWQA National Water Quality Assessment

NEP National Estuary Program

NPDES National Pollutant Discharge Elimination System

NTU Nephelometric T urbidity U nit

PLRG Pollutant Load Reduction Goal

QA/QC Quality Assurance/Quality Control

RPS Rapi d Periphyton Survey

RTAG Regional Technical Assistance Group

SAV Submerged Aquatic Vegetation

SBIO Statewide Biological Database

SCI Stream Condition Index

sej Solar Emergy Joule

SFWMD South Florida Water Management DistrictState of Florida Numeric Nutrient Criteria Development Plan March 2009

ix SJRWMD St. Johns River W ater Management District

SOP Standard Operating Procedure

SPI Stream Periphyton Index

STORET Storage and Retrieval (Database)

SWIM Surface Water Improvement and Management

TAC Technical Advisory Committee

TKN Total Kjeldahl Nitrogen

TMDL Total Max imum Daily Load

TN Total Nitrogen

TOC Total Organic Carbon

TP Total Phosphorus

TSI Trophic State Index

TSS Total Suspended Solids

USGS U.S. Geological Survey

WBID Waterbody Identification N umber

WRAP Wetland Rapid Assessment Procedure

**μ** g/L Microgr ams per L iter
μmho/cm Micromohs per C entimeterState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 1 

## STATE OF FLORIDA NUMERIC NUTRIENT CRITERIA

DEVELOPMENT PLAN

1

. Background and Criteria Development Process

The s tate of Florida intends to adopt quantitative nutrient water quality standards to facilit ate the assessment of designated use attainment for its waters and to provide a better means to protect
state waters from the adverse effects of nutrient over enrichment. To that end, the Florida Department of Environmental Protection ( FDEP ) plans to deve lop numeric criteria for causal variables ( phosphorus and nitrogen ) and /or response variables ( potentially chlorophyll a and transparency )

, recognizing the hydrologic variability (waterbody type) and spatial variability (location within Florida) of the nut rient levels of the state’s waters

, and the variability in ecosystem response to nutrient concentrations

.

It is FDEP ’s intent to establish numeric nutrient criteria that are protective of designated uses and consistent with Florida’s existing narrative n utrient criterion, which states that “in no case shall nutrient concentrations of body of water be altered so as to cause an imbalance in natural populations of flora or fauna.” Therefore, FDEP’s preferred approach is to develop cause/ effect relationships between nutrients and valued ecological attributes, and to establish nutrient criteria

that en sure that the designated uses of Florida’s waters are maintained.

Nutrients are unlike any other “pollutant” regulated by the federal Clean Water Act (CWA) . Mo st water quality criteria are based on a toxicity threshold, evidenced by a dose

- response relationship, where higher concentrations can be demonstrated to be harmful, and acceptable concentrations can be established at a level below which adverse response s are elicited (usually in laboratory toxicity tests). In contrast, nutrients are not only present naturally in aquatic systems, they are absolutely necessary for the proper functioning of biological

communities , an d are sometimes moderated in their expres sion by many natural factors

.

Therefore, the development of protective nutrient criteria is immensely more complicated than that for toxic substances. It must be recognized that nutrients should not be regulated at levels

that are artificially lower than those concentrations required for normal ecosystem functioning. If humans were to reduce nutrients below the levels that natural aquatic systems are accustomed to, adverse biological effects (disruption of trophic dynamics, loss of representative taxa) wo uld

occur. This would be counter to the C WA charge in Section 101 to “protect the physical, chemical, and biological integrity” of the state’s waters and

, coincidentally, against Florida law

, which prohibits F DEP from conducting remediation for natural co nditions. Ideally, nutrients should be managed in a range of concentrations with some consideration of a margin of safety on both the upper and lower bounds of the range.

A memorandum from the Director of the U.S. E nvironmental Protection Agency’ s (EPA) O ffice of Science and Technology, Geoff Grubbs (2001)

, indicate d that states are allowed the flexibility to develop and adopt nutrient criteria other than those currently proposed by EPA for waterbody types in specific N utrient E coregions which were aggr egated from Level III ( EPA

, 1998) ( Figure 1 and Table 1 ). As proposed , the EPA criteria recommendations that would

include Florida ( EPA

, 2000a, 2000 b, 2000 c, 2000 d, and 2000 e) do not fully reflect localized conditions or specific waterbody designated uses within the State of Florida

, FDEP proposes to

undertake activities to develop criteria for lakes, streams, estuaries

, coastal waters, and wetlands within the state, based on state

- specific, subregional data

. Upon issuance of §304(a)State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 2 Ecoregional Nutrient Criteria Recommendations, and since that time , EPA has encouraged states to refine their approach where possible in order to reflect more state

- specific data and

conditions.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 3 

### Figure 1. Draft a ggregations of Level III e coregions for the n ational n utrient

s trategy in FloridaState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 4 

### Table 1. EPA

- g enerated n utrient c riteria r ecommendations for n utrient

e coregions

, i ncluding all or p art of Florida

**Lakes and Reservoirs**

Parameter Region

IX 1 Region

XII 2 Region

XIII 3

TP ( **μ** g/L) 20 10 17.5

TN (mg/L) 0.36 0.52 1.27

Chlorophyll a ( **μ** g/L) 4.93 2.6 12.35

Secchi D epth (m) 1.53 2.1 0.79

m

– Meters.

**μ** g/L

– Micrograms per liter. mg/L

– Milligrams per liter. 

### Rivers and Streams

Parameter Region

IX 4 Region

XII 5 Region

XIII 6

T P ( **μ** g/L) 36.56 40.0 N/A

T N (mg/L) 0.69 0.9 N/A

Chlorophyll a ( **μ** g/L) 0.93 0.40 N/A

Periphyton Chlorophyll a (mg/m 3 ) 7 20.35 N/A N/A

Turbidity (NTU) 5.7 1.9 N/A

mg/m 3

– Milligrams per cubic meter.
N/A

– N ot available

. NTU

– Nephelometric turbidity unit.

TP

– Total phosphorus.

TN

– Total nitr ogen.

1 EPA

, 2000a.

2 EPA

, 2000b.

3 EPA

, 2000c.

4 EPA

, 2000d.

5 EPA

, 2000e.

6 EPA has not issued ambient water quality criteria recommendations in support of the development of nutrient criteria for rivers and streams in Nutrient Ecoregion XIII.

7 Only th e guidance for rivers and streams in Nutrient Ecoregion IX included recommendations for

p eriphyton c hlorophyll a

.

The d evelopment of criteria for these subregions has been and will continue to be prioritized based on Florida’s watershed program needs and the availability and order of EPA guidance

documents. FDEP will evaluate both ecoregions and bioregions as potential subregionalization

bases for numeric nutrient criteria. Florida ecoregions were delineated in the early 1990s as part of Florida’s biocri teria development efforts for streams and lakes. Those efforts yielded 13

L evel IV subecoregions (Griffith et al

., 1994) for wadeable streams ( Figure 2 ) and 47 L evel IV subecoregions (Griffith et al

., 1997) for lakes ( Figure 3 ). Additionally, FDEP has an alyzed stream reference site macroinvertebrate community patterns in all 9 ecological subregions north of Lake Okeechobee (Barbour et al

. , 1996). From that a nalysis , FDEP concluded that t he data

indicated the presence of 4 distinct bioregions, within whic h there were similar biological community composition and structure ( Figure 4 ).

While FDEP plans to develop nutrient criteria that ar e applicable to specific regions which will serve to prevent impairment , t he conceptual approach outlined in this document also incorporates the state’s responsibilities to address existing nutrient impairment through the development of Total Maximum Daily Loads ( TMDLs ) or Pollutant Load Reduction Goals (PLRGs)

, as described in state laws and rules

, both of which may serve to develop more site

-State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 5 specific nutrient targets that could super s ede regional criteria , if subsequently adopted and approved as site specific alternative criteria . For example, FDEP has developed and received approval from EPA Region 4 for the Lake Okeechobee phosphorus TMDL, which established the phosphorus concentration that would address undesirable algal blooms in that system. Similarly, the Tampa Bay Estuary Program has adopted chlorophyll a targets for portions of Tampa Bay that were specifically design ed to protect and restore seagrass communities within the bay. The program has established a protocol that considers the magnitude, frequency, and

duration of changes to algal biomass in the bay and implemented through agreements, a program to control exc ess nitrogen in the watershed

.

It should be noted that FDEP intends to develop numeric nutrient criteria for adoption in Chapter

62

- 302, Florida Administrative Code (F

. A

. C

. ), as water quality criteria, and in addition, is exploring the incorporation of num eric nutrient thresholds into the Impaired Surface Waters Rule (IWR ) ( Chapter 62

- 303, F

. A

. C

. ), which establishes the s tate’s methodology to identify and verify impaired waters (waters not meeting applicable water quality standards). While the IWR already includes thresholds for response variables that serve as translators for Florida’s narrative nutrient standard (a quantification of imbalance of flora and fauna) which are used in

addition to consideration of other factors to assess waters for nutrient im pairment the IWR does not currently include numeric causal thresholds for either streams or estuaries . Such

additional numeric nutrient thresholds adopted in the IWR would serve as nutrient impairment

thresholds for those waterbody types . Once developed, numeric nutrient criteria are intended to both protect healthy

, well

- balanced natural populations of flora and fauna from the effects of

excess nutrient enrichment , as well as provide a basis to identify waters already impaired by

nutrients.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 6 

### Figure 2. L evel IV s ubecoregions for Florida: Small/ w adeable s treams

A

l a

b a

m a

G e o r g i a

G

u l

f o

f M

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)

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5 7

)

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C

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s ( 7

5 3

)

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A

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m i c C o a s t a l S

t r i p ( 7 6 3

)

S o u t h e r n C o a s t a n d I s l a n d

s ( 7

6 4

)



## L

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### G r i f f i t h 1 9 9 4State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 7 

### F igure 3. Level IV s ubecoregions for Florida l akes

A

l a b a m a

G e o r g i a

G

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## L

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### G r i f f i t h 1 9 9 7State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 8 

### F igure 4. Stream b ioregions of FloridaState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 9 

## 1.1 Use of a Technical Advisory Committee

To assist in the development of numeric nutrient crit eria, FDEP convened a N utrient C riteria Technical Advisory Committee ( TAC ) in 200 3

, compris ing individuals with expertise in areas related specifically to water quality and biological community response to nutrients in Florida ( Table 2 )

. The TAC members hi p is diverse, consisting of representatives with significant experience in the ecology of specific aquatic systems (lacustrine, riverine, estuarine, and / or palustrine) and the interpretation of water quality data through the use of statistical modeling

too ls. These individuals were cho sen for their ability to provide advice and guidance in the dynamics of these aquatic systems, as well as to represent the diverse parties in Florida

interest ed in the development of nutrient criteria. They include represent atives of academic and public institution s , along with individuals possessing significant technical experience who were drawn from industry, agricultur al , and environmental groups.

The TAC is charged with review ing the existing knowledge base related to these aquatic systems and develop ing recommendations to FDEP on numeric nutrient criteria. The TAC is supported by FDEP staff assigned to provide data assembly and analysis. T he TAC process to date, along with further in

- depth evaluations of available d ata and the existing knowledge base by FDEP staff have clear ly indicated that there are numerous remaining technical complexities and limitations associated with the verification, analysis, and synthesis of the currently available

data for the derivation o f numeric nutrient criteria . Given these complexities, FDEP has decided

to extend t he TAC process through 2009 at a minimum

. FDEP anticipate s that smaller subgroups may need to be formed to consult with other experts in address ing specific waterbody typ es ( e.g

., south Florida canals , or estuaries ) for which criteria are under development

.

FDEP has assigned a dedicated staff member to coordinate the development of numeric nutrient criteria. This nutrient coordinator is responsible for communicating with EPA, the TAC, and other interested parties on the development of nutrient criteria

, and also ensuring that the process is properly integrated with other FDEP program areas.

In accordance with Florida’s Sunshine Law, all meetings of the TAC have been and w ill continue to be open to the public. To further promote public awareness and involvement in the process, each TAC meeting incorporates designated periods for informal public participation and comment. In recognition of the large geographic span of the state, TAC meetings are held at different locations within Florida on a rotating basis. Also, a link on the FDEP website ( http://www.dep.state.fl.us/water/wqssp/nutrients/index.htm ) has been established to report all

TAC activities.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 10 

### Table 2

. FDEP Nutrient Criteria T AC m embers

Name Affiliation Experience Relevant to TAC Appointment

Kevin Carter South Florida Water Management

District Nominated by Florida League of Cities Estuari ne systems
Canals

Douglas Durbin, Ph.D. Biological Research Associates, Inc. Nominated by Florida Phosphate

Council Riverine systems Lacustrine systems Wetland systems

Canals

Mark W. Clark, Ph.D. University of Florida, Department of Soil

and Water Scienc es Wetland systems Nutrient dynamics and eutrophication

Ed Decker EPA Region 4, Atlanta EPA Regional Nutrient Coordinator Aquatic biology and chemistry

Wastewater treatment Nonpoint source control Surface water monitoring & assessment

Anthony Federico Ma cVicar, Federico and Lamb, Inc. Nominated by Florida Department of

Agriculture and Consumer Services Lacustrine systems Estuarine systems Riverine systems Water quality modeling

FDEP Lake Okeechobee TAC

Robert Fisher, Ph.D. National Council for Air and S tream Improvement, Inc. Nominated by Florida Pulp and Paper

Association Riverine systems

EPA Gulf of Mexico Program Nutrient

Enrichment Focus Team

John Hendrickson St. Johns River Water Management

District Lacustrine systems Riverine systems FDEP Impaired Waters T AC (Alternate)

Mark Kraus, Ph.D. Everglades Foundation Wetland systems Estuarine systems

Frank Marshall, Ph.D., P.E

. Environmental Consulting & Technology, Inc. Nominated by Florida Stormwater

Association Estuarine systems

Canals Water quality m odeling

Scott McClelland Camp Dresser & McKee, Inc. Water quality modeling FDEP Impaired Waters TAC



## 1.2 Post

- TAC Rule Development

After the completion of TAC activities and before the submittal of potential criteria to the state’s Environmental Regul ation Commission (ERC), FDEP will hold rule development workshops,

share draft rule text with the public , and allow for public review and comment , as required by

both state and federal regulations

. The ERC is an unpaid citizenry board appointed by the
Gov ernor of Florida . I n exercising its authority, it considers scientific and technical validity, economic impacts, and relative risks and benefits to the public and the environment of all proposed rules and standards related to environmental resources. It is anticipated that ERC activities can be completed in 6 to 12 months, barring major dissent or administrative challenge

. However, t he level of control that FDEP has over the schedule of the ERC’s approval process for such rules is limited, making the est ablishment of a firm completion date for nutrient criteria adoption difficult. I f there is an administrative challenge to the proposed criteria, the administrative hearing process would likely take at least a nother year. FDEP however, remains

committed t o a timely completion of this effort.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 11 

## 2

. Nutrient Criteria Development and Implementation

2.1 EPA Guidance

EPA’s Nutrient Criteria Technical Guidance Manual : Rivers and Streams ( Buck et al.

, 2000) described three general approaches, with certain options, for the development of numeric nutrient criteria for streams. The most comprehensive and scientifically defensible approach (the s tate’s preferred approach) is to establish criteria to protect against dependably measured adverse biological responses. EPA suggests that an observed dose

- response relationship could be described by a model ( e.g., trophic state classification, regional predictive model,

b iocriteria , etc.), which in turn would link nutrient concentrations to the relative risk of

environmental h arm.

FDEP supports this approach, since it establishes a cause/effect relationship between nutrients and valued ecological attributes, and is linked to maintaining designated uses. FDEP is currently pursuing response

- based thresholds for use as water qu ality criteria for inclusion in the state’s water quality standards rule, Chapter 62

- 302, F.A.C. In a series of studies (described in

detail in Section 3 )

, FDEP is investigating the relationship between nutrients and biological

measures such as the Stream Condition Index (SCI) , Lake Vegetation Index (LVI), Stream

P eriphyton Index (SPI) (currently under development) , and phytoplankton chlorophyll a

.

In the absence of data quantitatively describing biological dose

- response relationships, EPA

recommends as th e next best alternative, setting criteria based on an inclusive distribution of values obtained from minimally disturbed reference sites in a designated ecoregion (based on climate and geology) and recommends projection an upper percentile value to represe nt a level

of nutrient concentration that will inherently protect aquatic life

. It should be noted that EPA ’s guidance for both rivers & streams, and lakes & reservoirs suggests using the 75 th percentile (but only as a suggestion) , and that a higher perce ntile might be chosen when associated with high er confidence in the reference set that can reduce uncertainty with regard to protection

. EPA’s more recent guidance for wetlands suggests that using the 75 th to 95 th percentile may be appropriate. According to published EPA guidance, reference reaches may be ident ified for

each class of stream within a state based on b est professional judgment

. FDEP also supports this methodology, since it would ensure that nutrient concentrations associated with biologicall y healthy, well

- balanced communities would be considered acceptable as protective of those

communities

.

However, this approach as described above is an inference model, and does not definitively

demonstrate that exceeding the threshold established by the distribution of reference sites

results in harm (impairment) to the aquatic life in a particular waterbody. Multiple factors can strongly influence the expression of biological responses to nutrients across waterbodies

, such

as water velocity, residence time, availability of the other nutrient, presence of grazers, availability of light ( due to tree cover and /or water transparency ), and availab ility of suitable habitat. In fact, FDEP has found in Florida waters that additional stressors ( e.g

., degrade d habitat, unfavorable hydrology) often influence biological impairments more than the actual

concentration of nutrients at a given point . The “minimally affected reference water approach” identifies concentrations that are presumed to be inherently prote ctive of the waterbody (including downstream waters) because these concentrations a re associated with demonstrated minimally disturbed systems with healthy biological communities. Actual biological thresholds

can be site

- specific and arguably more precise

.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 12 The third and least preferred approach of those suggested by EPA is offered for use in

situations where sufficient known reference sites are unavailable, either absent or not identifiable. This approach is often referr ed to as t he “all streams” appr oach, and involves establishing criteria using a lower distribution ( e.g

. , 5 th to 25 th percentile) of a pool of sites of

undetermined ecological quality , as long as the pool is sufficiently large enough to represent all waters and can be presumed to reason ably reflect the full range of ambient conditions with a disturbance gradient from least to most impacted

. Due to the intended scale of application and the availability of data, EPA used this method to develop and publish under CWA §304(a)

recommended nut rient criteria for streams and lakes in Nutrient Ecoregion s IX, XII, and XIII. However, after careful review of the se recommended criteria

, FDEP has concluded that they are

not sufficiently defensible (see Appendix B ). In FDEP’s opinion, this “all sites data distribution approach” does not directly link nutrient concentrations to valued ecological attributes (healthy

, well

- balanced populations of flora or fauna) , and consequently

, FDEP believes that other options are preferable and more scientifically jus tified

. For this reason, FDEP considers the “ all sites data distribution approac h” to have limited defensibility in Florida

, and therefore does not intend to pursue it any further

.



## 2.2 FDEP’s Approach

The CWA provides states with three alternative paths f or development of protective numeric criteria (40 CFR 131.11). Numeric criteria may be established based up on (1) published
Section 304(a) guidance

, or (2) 304(a) guidance modified to reflect site

- specific conditions

, or (3) by use of other scientifically defensible methods ( referred to later in this document as “Option 3”)

. Based on extensive experience with the development of biocriteria

, FDEP has gained significant knowledge and expertise in the objective quantification of human disturbance

and charact erization of biological response. Therefore, FDEP intends to pursue the CWA option that allows criteria to be based on a state

- defined

, scientifically defensible method (O ption 3) for the purposes of developing numeric nutrient criteria to provide protect ion and

maintenance of aquatic life use in Florida

.

FDEP plans to d evelop numeric nutrient criteria using response

- based relationships that are

consistent with the existing narrative criterion for nutrients , which states “ I n no case shall

nutrient concentr ations of body of water be altered so as to cause an imbalance in natural populations of flora or fauna.” The d etermination that an “imbalance” has occurred requires an evaluation of the relationship between nutrients and biological health ( while attempti ng to control for confounding variables ) and include s the following :



### • Defining the expected biological integrity (aquatic community structure and function) by examining minimally disturbed sites in the ecosystem. This is accomplished by developing and cali brating biological indices. F DEP has , or is developing, indices for stream invertebrates, lake plant communities, and stream algae.



### • Sampling key water quality parameters and biological communities (e.g., algae, macrophytes, and invertebrates) across a nut rient gradient.



### • Determining where along the nutrient gradient, and at what concentrations, significant departures in the expected community structure and function occur compared with acceptable conditions , using EPA ’s Biological Condition Gradient (BCG) approach (Davies and Jackson

, 2006 ; Stoddard et al.

, 2006)

.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 13 The BCG concept definitively describes how the following ten ecological attributes change in response to increasing levels of stressors :

**•** Historically documented, sensitive, long

- lived

, or region ally endemic taxa ;

**•** Sensitive and rare taxa ;

**•** Sensitive but ubiquitous taxa ;

**•** Taxa of intermediate tolerance ;

**•** Tolerant taxa ;

**•** Non

- native taxa ;

**•** Organism condition ;

**•** Ecosystem functions ;

**•** Spatial and temporal extent of detrimental effects ; and

**•** Ecosystem connectedn ess

.

Based on the above attributes, the BCG model segregates biological condition into six tiers , as follows, which F DEP believes are especially useful for nutrient criteria development efforts :

(1) Native structural, functional, and taxonomic integrity is p r eserved; ecosystem

function is preserved within the range of natural variability

. (2) Virtually all native taxa are maintained

, with some changes in biomass and/or abundance; ecosystem functions are fully maintained within the range of natural variability

. (3) Som e changes in structure occur due to the loss of some rare native taxa; there

are shifts in the relative abundance of taxa

, but sensitive

– ubiquitous taxa are common and abundant; ecosystem functions are fully maintained through

redundant attributes of the s ystem

. (4) Moderate changes in structure occur due to the replacement of some sensitive

– ubiquitous taxa by more tolerant taxa, but reproducing populations of some sensitive taxa are maintained; there is overall balanced distribution of all expected major group s; ecosystem functions are largely maintained through redundant

attributes

. (5) Sensitive taxa are markedly diminished; there is a conspicuously unbalanced distribution of major groups from that expected; organism s show signs of physiological stress; system fu nction shows reduced complexity and redundancy; increased buildup or export of unused materials occurs

. (6) Extreme changes in structure take place ; there are wholesale changes in taxonomic composition; extreme alterations from normal densities and

distributio ns occur ; organism condit ioning is often poor; ecosystem functions are severely altered

.

The BCG model is consistent with ecological theory and enables ecologically relevant interpretations of the response of aquatic biota to stressors. EPA has extensive ly tested t he

BCG model in various parts of the country with regionally diverse panels of biologists, (often

includ ing a n FDEP representative )

, who typically converge on agreement in assign ing specificState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 14 taxa in samples of macroinvertebrates or fish to the six tiers as de s cribed above

. This process has proved to be a very reliable and consistent to interpret stress on aquatic life and inform agency decision making processes

. Based on two independent calibrations of Florida’s biological indices, as well as i nput from several National BCG Workshops, F DEP has

determined that sites associated with BCG scores of 5 and 6 do not meet the criteria for the

s tate’s designated use of “ healthy, well

- balanced communities of aquatic flora and fauna

. ”

For numeric nutrient criteria development purposes, the use of the BCG has several implications. Its use may result in the determination that acceptable levels of nutrients may (or may not) be higher than historic al background conditions, since well

- defined biological respon se end points are used for the assessment. Also, because biological communities respond to all sources of stress (natural and anthropogenic), the model offers a mechanism to evaluate potential stressors and to control for confounding variables during the a ssessment process. Finally, since the BCG model is based on sound, nationally accepted ecological concepts, the ranges of nutrients deemed acceptable through its use will result in scientifically defensible

criteria.

While FDEP has and will continue to pu rsue all scientifically defensible approaches to derive numeric nutrient criteria, it prefers to base criteria on dose

- response relationships. In acknowledgement of the challenges associated with identifying statistically significant relationships between nutrient concentrations and biological responses, FDEP is also developing nutrient criteria using a “ benchmark distributional approach ” that will serve as potential “backup” criteria i f that statistically sound dose response

– based criteria cannot be

initi ally determined. However, in addition FDEP may adopt criteria developed from the benchmark distributional approach in Chapter 62

- 303, rather than Chapter 62

- 302, F.A.C., and may require biological confirmation before listing waters as impaired

.

The nutr ient benchmark distributional approach builds on methodologies originally developed to quantify human disturbance for biocriteria development purposes

. By FDEP’s definition,

nutrient benchmark site s are only influenced by low levels of human disturbance

, enabling ful l support of the most sensitive designated use

— i.e.

, support of a healthy

, well

- balanced population of fish and wildlife. FDEP intends to use the upper end of nitrogen and phosphorus frequency distributions from benchmark sites to define nutr ient thresholds that FDEP expects to
be both defensible and reliable for protection of aquatic life in Florida waters

.

If the benchmark

- based nutrient thresholds are adopted in Section 62

- 303.300 , F.A.C

. , t hese

thresholds would be used to identify waters that are potentially impaired for nutrients. Waters

with nutrient concentrations above these thresholds would be placed on the s tate’s P lanning L ist of potentially impaired waters and prioritized for additional monitoring

. A subsequent biological

confir mation linking biological impairment instream at that point, or possibly downstream, to excess nitrogen or phosphorus would be required for a water body to be included on the V erified

L ist of impaired waters ( Section 62

- 303.400, F.A.C.). If no biologic al i mpairment can be

demonstrated for waters ( or downstream of waters) placed on the Planning L ist for nutrients, or if the biological impairment is shown to be due to factors other than nutrients

, then the se water s would not be considered impaired due to nutr ient enrichment.

FDEP believes that a site

- specific biological confirmation is required to demonstrate a link between nutrients and adverse biological responses for nutrient benchmark approach

– derived

criteria

. M ultiple factors can strongly influence the expression of biological responses to

nutri ents across natural waterbodies

, and multiple additional stressors ( e.g ., habitat, hydrology) are often more influential on biological impairments than nutrients

. The benchmark

distributional approach identifies nutrient concentrations that are presumed protective becauseState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 15 these concentrations are associated with relatively low human disturbance and health y biological communities instream at that point

, and shown to be protective downstream . Actual biological thre sholds will be site

- specific and could occur at concentrations above or below the

benchmark thresholds

, depending on circumstances

.



## 2.3 Implementation

T he specific rules in which nutrient criteria are adopted affect the breadth of the CWA programs under wh ich they are implemented. While nutrient thresholds adopted in the IWR may result in identifying waters to be addressed by the development of TMDLs which will establish effluent limitations via wasteload allocations, the se thresholds would only apply for the purposes of assessment and listing under CWA S ections 303(d) and 305(b) . In contrast, criteria established in Chapter 62

- 302, F.A.C., would be implemented in the IWR and would also be used to directly

establish effluent limits and water quality target s for TMDLs

.

T able 3 provides a basic overview of the regulatory structure in which criteria will be adopted in

Florida and summarizes the progress made or planned for such adoption.



## 3. Technical Approaches

FDEP is committed to using technically defensible methods and the most robust dataset

feasible to develop protective nutrient criteria for Florida’s waters. Since there is a lack of data describing biological dose

- response relationships for nutrients, FDEP initially pursued a nutrient

benchmark distribu tional approach. However, the state’s preference is to develop criteria linked to biological response. Given this preference, FDEP has continued efforts, including initiating studies in 2008, to develop response

- based criteria for adoption in Chapter 62

- 302, F.A.C. FDEP’s ongoing and planned studies are described below.



## 3.1 Initial Investigations

In 1999, FDEP’s Division of Water Resource Management initiated the implementation of a watershed approach patterned after EPA guidance (EPA

, 1991, 1995), inclu ding the prioritization of waterbodies for TMDL development. FDEP has drawn on the lessons learned and knowledge gained through these processes to prioritize the development of numeric

nutrient standards. FDEP also managed five external projects, complet ed between 2001 and 2003, that focused on specific approaches outlined in EPA nutrient guidance documents ( USEPA

, 2000 ; USEPA

, 2000). The idea was to see if these approaches would be feasible on a regional scale. The projects were as follows:

(1) Paleolimnol ogical characterization of predisturbance water quality in two Florida lake regions ;

(2) Sedimented algal pigment profiles in the Florida paleolimnological study lakes ;

(3) Development of stream diatom population indices for Florida streams ;

(4) Comparison of nutrient criteria approaches for Florida lakes with recommendations for TN, TP, c hlorophyll a, and Secchi depth criteria ; and

(5) Another paleolimnological study with further resolution on the lakes in Studies 1

and 2 above.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 16 It was determined that some of these appro aches, while excellent for a specific waterbody, were

too time

- and cost

- intensive for a subregional approach. However, the se efforts provided information and insight into both the causal and response aspects of waterbody nutrient status

at both site

- spec ific and ecoregional levels. FDEP also anticipates the possibility of applying for funding on additional projects.



### Table 3

. Summary of r egulatory s tructure and p rogress towards a dopting

nutrient c riteria in Florida

Rule and Applicable

Waterbody Type Ca usal Variables (Nitrogen and Phosphorus) Response Variables

Section

62

- 303.300s

, F.A.C. ; Planning List Rivers &

Streams Under Development (planned for 2010)

Will either revise rule to implement criteria adopted in Chapter 62

- 302, F.A.C., or will adopt b enchmark

- based thresholds in rule Chlorophyll a (adopted * )

S CI (adopted) Turbidity (adopted)

Lakes Under Development (planned for 201 0 )

Will either revise rule to implement criteria adopted in Chapter 62

- 302, F.A.C., or will adopt benchmark

- based thresho lds in rule Trophic State Index (TSI) (adopted * )

L VI (planned for 2009 )

Estuaries Kickoff in 2008 (planned for 2010) Chlorophyll a (adopted * )

Wetlands Lower Priority Wetland Condition Index, which includes vegetation, algae, and invertebrates. This

in dex still needs development, calibration

and validation.

Section

62

- 303.400s

, F.A.C. ; Verified List Rivers &

Streams Under Development (planned for 2010) Will either revise rule to implement criteria adopted in Chapter 62

- 302, F.A.C., or will adopt bench mark

- based thresholds in rule Chlorophyll a (adopted * )

SCI (adopted) Turbidity (adopted)

Lakes Under Development (planned for 201 0 ) Will either revise rule to implement criteria adopted in Chapter 62

- 302,

, F.A.C., or will adopt benchmark

- based threshold s in rule T SI (adopted * )

LVI (planned for 2009 )

Estuaries Kickoff in 2008 (planned for 201 0 ) Chlorophyll a (adopted * )

Wetlands Everglades phosphorus criteria via application of criterion in Chapter 62

- 302

, F.A.C. Lower Priority Wetland Condition Index, which includes vegetation, algae, and invertebrates . This

index still needs development, calibration

and validation.

Section

62

- 302.500s

, F.A.C. ; TMDLs &

Permit Limits Rivers &

Streams Under Development (planned for 201 0 )

Proposed nitrate criteria for springs as part of ongoing Triennial Review (2009) Transparency Criterion (adopted, with plans

to specifically address submerged aquatic vegetation [ SAV ] in 2009 )

S CI (planned for 2009 ) Periphyton Index (planned for 2011)

Lakes Under Development (planne d for 201 0 ) Transparency Criterion (adopted, with plans

to specifically address SAV in 2009 )

L VI (planned for 2009 )

Estuaries Kickoff in 2008

, Under Development (planned for 201 0 ) Transparency Criterion (adopted, with plans

to specifically address SAV i n 2009 ) Under Development (planned for 2011)

Wetlands Everglades phosphorus c riteria (adopted) Under Investigation (science incomplete, lower priority) Wetland Condition Index, which includes vegetation, algae, and invertebrates

. This

index still needs calibration and validation

.

* approved by EPA as “one

- sided” thresholds which serve as translators for the state’s existing narratives in assessment activities by providing a threshold above which waters are impaired , but not by design, a threshold belo w which uses are known to be protected.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 17 

## 3.2 Biological Criteria Development

FDEP has made very significant progress in the development of biological indices specifically designed to assess the health of aquatic biological communities. Fore et al . (20 07a) developed

a n SCI to assess the biological condition of macroinvertebrates in Florida st r eams. Additionally,

Fore et al

. (200 7 b ) developed a n LVI to assess the biological condition of aquatic plant

communities in Florida lakes. FDEP plans to adopt bo th the SCI and LVI into the state standards as water quality criteria during its ongoing triennial review , which started in 2008

.

In order t o furthe r strengthen its bioassessment capabilities, FDEP is adding another tool that can be expected to augment or compliment the SCI and LVI described above, and provide a potential indicator with increased sensitivity to nutrients. Work to develop a Stream Periphyton Index ( SPI ) for Florida began during the last quarter of 2007 , and s ignificant progress is expected by early 2009

. FDEP also began using a Rapid Periphyton S urvey (RPS) methodology for streams in early 2007 ( FDEP S tandard Operating Procedure [S OP ] FS 7230 ) ( FDEP

, 2008) . The RPS provides an assessment of the extent and thickness of periphyton in

stream s and the type of periphyton present ( i.e ., diatom or filamentous). Both the SCI and LVI were successfully calibrated for Florida waters, and FDEP has actively worked with EPA to hold

a BCG workshop for the SPI in late February, 2009, but it is too early to tell whether FDEP will

have the same success with periphyton

.

The biological criteria and indices developed for Florida provide measures of biological heath that can be used to support the derivation of protective numeric nutrient criteria. Nutrient

co ncentrations associated with “healthy or exceptional” bioassessment index values would be compared to nutrient concentrations associated with “impaired” biological index scores to establish protective nutrient criteria (including adoption of an appropriate margin of safety). Biological health measures can be used to both demonstrate healthy

, well

- balanced populations

of flora or fauna within benchmark waters and as thresholds of biological impairment for stre ssor

response

– based approaches. Additionally, t he adoption of the SCI and LVI into state water quality standards will provide FDEP with additional measures of biological impairment that can be linked to violations of the existing narrative nutrient criteria 1



## 3.3 Nutrient Gradient Stream Study and thus provide an added level of protectio n against the anthropogenic nutrient enrichment of Florida’s waters. FDEP ’s significant investment in the development of biological indices and criteria has put the state in a strong position to complete the development of highly defensible numeric nutrie nt criteria within

th e time frames described in Section 9 of this plan

.

As noted previously, the most comprehensive and protective approach to develop numeric nutrient criteria is to establish criteria to protect against scientifically determined adverse biological responses. EPA suggests that an observed dose

- response relationship should be described by a model ( e.g., trophic state classification, regional predictive model, biocriteria),

which in turn would link nutrient concentrations to the relative risk of environmental harm.

Although Florida will continue to work on the development of numeric nutrient thresholds using

the benchmark distributional approach as a backup

, FDEP is actively investigat ing approaches

that mor e directly link nutrient levels to biological responses. A study designed to establish

1 Nutrients must be identified as the causative or contributing pollutant prior to a determination that there is a violation of the narrative criterion. The impairment of biological criteria can also be linked to other stressors such as toxicants, habitat, or hydrologic

modifications.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 18 nutrient concentrations associated with adverse biological responses, called the Nutrient Gradient Study, was initiated in the spring of 2008.



### 3.3.1 **Study Objectives**

Th e study is specifically designed to provide information necessary to develop nitrogen and phosphorus criteria for streams , although chlorophyll and transparency measure s will also be

evaluated and considered. Its objectives are as follows:

**•** Collect physica l, chemical, and biological data on Florida streams to establish the relationship between nutrient levels and adverse biological responses ; and

**•** Analyze the resulting dataset as one line of evidence in FDEP’s effort to establish

numeric nutrient criteria.



### 3.3.2 **Study Meth o**  **dology**

Unlike other pollutants, nutrients are not only naturally present, they are necessary at some level for the proper functioning of ecosystems. Biological communities evolve in response to the existing physical and chemical character istics to which they are exposed. In the case of nutrients, the biological communities that develop are the ones best able to compete for and

utilize the available nutrients in an ecosystem

, given the other characteristics of the system. Changes in the n atural nutrient regime

— either increased or decreased nutrient levels

— can cause shifts in the structure of the biological communities present and ultimately the function of the system. To derive appropriately p rotective nutrient criteria, this approach rel ate d nutrients to ecological health and biological response. Other factors that also affect biological health ( e.g

., hydrologic modification, habitat, canopy cover) were measured to help determine their relative influence on the biological responses under the observed nutrient regimes.

Each of FDEP ’s six District offices sample d 12 to 15 sites from a list of 20 potential nutrient gradient sites. Two sampling events were conducted , one during spring/summer 2008 and the other during fall/winter 2008

– 09

. Al l samples were collected according to FDEP

- SOP

- 001/01. Sampling will be completed by January 2009 . The Bureau of Laboratories in Tallahassee will analyze all samples.

The following were performed at each site:

**•** Hydrologic Modification Scoring ;

**•** S CI ;

**•** Hab itat Assessment (HA) ;

**•** Percent Canopy Cover ;

**•** Rapid Periphyton Survey ;

**•** Qualitative Periphyton Collection ;

**•** Linear Vegetation Survey ;

**•** Meter R eadings (dissolved oxygen [DO] , specific conductivity, pH, and temperature) ; and

**•** Water Chemistry ( total Kjeldahl nitr ogen [TKN] , TP, ammonia, nitrate

- nitrite, turbidity, chlorophyll a, color, t otal o rganic c arbon [TOC]

, t

otal s uspended s olids [TSS] ).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 19 A majority of the sites were selected from a previous statewide intensive Dissolved Oxygen Study conducted in 2005 and 2 006

, and included sites with a variety of Land Development Intensity ( LDI ) Index scores and nutrient regimes. Additional sites were located near National Pollutant Discharge Elimination System ( NPDES ) point sources with known nutrient

- enrichment

issues. Sites we re geographically diverse in an attempt to represent as much of the s tate as possible. T he following t wo types of sites were sampled :

**•** Sites located upstream and downstream from high

- nutrient point source discharges; and

**•** Sites located along a nutri ent gradient, with low, medium, and high nutrient regimes.

Since the objective of the study wa s to emphasize the effects of nutrients on biota, attempts

were made to minimize or account for confounding factors, such as poor habitat and highly modified hyd rologic regime . This especially applied to the sites not affected by point sources. In an effort to reduce the effects of confounding variable s , only sites with minimal to moderate levels of habitat or hydrologic modification, as determined by Florida’s HA and H ydrologic

M odification S coring , were selected . For the sites upstream and downstream from point sources, the most important factor was to ensure similar habitat and hydrology at the paired sites to emphasize the nutrient influences from the discha rge.

A primary purpose of this study wa s to determine the effects of nutrient concentrations on biological health. Habitat suitability (substrate diversity and abundance), flow, and length of

inundation wer e taken into account when deciding appropriate sites to sample. A n HA

, H ydrologic M odification S core , and P ercent C anopy C over were obtained at all sites to adequately characterize these important variables. Additionally, staff carefully assess ed the existing and antecedent flow conditions of each si t e to determine that conditions we re appropriate for the purpose of th e study. A site reconnaissance was also performed to make

sure the sites chosen we re appropriate for the study objectives.

Throughout the course of the study, each District collect ed on e water chemistry blank and perform ed duplicate sampling at a site with adequate habitat in order to assess the variability in SCI, RPS, and Qualitative Periphyton Collection results.



### 3.3.3 **Anticipate d**  **Study Outcomes and Statistical Approach** 

It is anticipa ted that this work, together with FDEP’ s existing extensive statewide biological

database (SBIO) , will provide information to establish causal link s between water column nutrient levels and adverse biological responses in plant, algal, and macroinvertebrat e communities. Nutrient concentrations associated with “exceptional” or “healthy” biological index scores (SCI, LVI, or SPI) will be statistically evaluated against the nutrient concentrations of sites with “impaired” index scores to determine potential d ose

- response relationships, including

the exploration of responses in individual metrics or attributes. If such cause

- effect relationship s

are discerned, the resulting criteria would include an appropriate margin of safety to ensure the protection of healt hy, well balanced aquatic communities.

Furthermore, it is anticipated that th e study will help to elucidate the effects of other variables ( e.g ., habitat, flow, canopy cover) on the expression of nutrients. A concurrently planned study

on stressor identif ication and the development of a statewide stressor identification model will complement this proposed work.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 20 F DEP anticipates that the statistical analysis of the resulting data will be sufficient ly rigor ous to
detect biological responses to nutrient enric hment. The ability to statistically determine patterns

in the data depends on sample size, the degree of variability in the data

, the level of significance

used

, and the desired power to detect differences among groups. F DEP will use the most

robust stat istics appropriate to the data characteristics generated from the study. It intends to investigate relationships between nutrient concentrations and biological response with several statistical tools, including the following :

**•** Ordinary least squares regres sion ;

**•** Quantile regression;

**•** Conditional probability analysis; and

**•** Change point analysis

.

F DEP will initially investigate biological responses to nutrient enrichment as univariate functions of either phosphorus or nitrogen, using the statistical tools list ed above. However, because biological response to nutrients is complex and influenced by numerous other ecological, hydrological, and biogeochemical factors, simple univariate models may not be sufficiently rigorous to support numeric nutrient criteria. If this is the case, F DEP will investigate more complex multivariate techniques that will take into account the influence of factors other than nutrients on biological response. Under this scenario

, F DEP will investigate statistical techniques such as the following :

**•** Multiple regression;

**•** Classification and ordination;

**•** Cluster analysis;

**•** Principle components a nalysis; and

,

**•** Canonical correspondence analysis.

This study will fill significant informational gaps in the understanding of stream flora and faun a responses to excess nutrient enrichment. Thus, it will help the state continue to make progress

towards the timely adoption of numeric nutrient criteria in the time frames presented in S ection

9 . Specifically, the state anticipates completing sample co llection by January 2009 and data analysis and synthesis within an additional four to five months thereafter

. FDEP anticipate s deriving numeric phosphorus and nitrogen criteria for Florida streams by December 2009, assuming the successful completion of th is project.

Note

, however, that if the results from th e study are of insufficient statistical rigor to promulgate scientifically defensible criteria, additional sampling and analysis may be needed, resulting in a

time extension. The results derived from th e study will be presented before FDEP ’s N utrient

C riteria TAC

.



## 3. 4. Development and Initial Application of the Nutrient Benchmark Distributional Approach

The TAC and FDEP staff discussed the benchmark distributional approach over the course of

numerous meetings. The TAC indicated its support for FDEP ’s proposed application of the overall approach (which includes the option of requiring confirmation of biological impairmentState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 21 and use of the resultant thresholds in the IWR rather than in Chapter 62

- 302, F.A .C.) and

recommended that FDEP needed to provide sufficient documentation substantiating low human disturbance levels and biological health ( i.e., supporting the designated use) of the selected

benchmark sites.

Based on the direction provided during TAC discussions in 2006, FDEP staff conducted a pilot study to develop nutrient criter ia for streams in the peninsula bioregion ( Figure 4 ) using the

benchmark distributional approach. FDEP developed and utilized an extensive multi

- step evaluation of potential benchmark sites to en sure that the sites used in the derivation of nutrient

thresholds for the peninsula bioregion truly represented low levels of human disturbance . This

multi

- step evaluation included the following:

(1) S creening for sites with a n LDI sco re less than or equal to 2 .0;

(2) S creening to exclude waters on the state’s 303(d) list of impaired waters ;

(3) Verifying surrounding land use using high

- resolution aerial photographs ;

(4) O btaining input from district biologists knowledgeable about the area ;

(5) Con ducting a statistical outlier analysis ; and

(6) Carrying out an extensive field evaluation of approximately 10% of the remaining waterbodies ( identified by **W** ater **b** ody **Id** entification number, or WBID 2 ) containing

benchmark sites.



### 3. **4.1 Identification of Candid**  **ate Benchmark**  **Sites (LDI)**

Candidate benchmark sites were initially selected based on an application of the LDI. Brown and Vivas ( 2005 ) developed the LDI as an estimate of the intensity of human land uses based on nonrenewable energy flow. The application of the LDI is based on the ecological principle that the intensity of human

- dominated land uses in a landscape affect s the ecological processes

of natural communities. More intense activities will result in greater effects on ecological processes. Natur al landscapes with little or no agricultural or urban development will likely have intact ecological systems and processes. The intended use of the LDI was as an index of the Human Disturbance Gradient (HDG)

.

The LDI is calculated as the area

- weighted val ue of the land uses within an area of influence. Using the land use coefficients and the percent area occupied by each land use as determined by geographic information system ( GIS ) land use coverages developed from high

- resolution aerial photographs, the LDI is calculated as follows:



### LDI Total 

### = **Σ** (LDC i 

### * %LU i 

### )

where,

LDI Total = L DI for the area of influence ;

%LU i = percent of total area of influence in land use i ; and

LDC i = LDI coefficient for land use i

.

2 WBIDs were originally developed for 303(d) assessment purposes an d were based on drainage basins defined by the U .S. Geological Survey (U SGS ) eight

- digit Hydrologic Unit Codes (HUCs).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 22 For the purposes of candidate benchmark sit e selection, LDI values were calculated from land

uses within a buffer area of 100 m on each side of the stream and 10 kilometers (km) upstream of the sampling point. Fore (2004) previously demonstrated that LDIs calculated using a 100 m buffer were sligh tly better predictors of biological health ( i.e., SCI) than LDIs calculated on the entire upstream catchment area (watershed).

The fact that an LDI calculated using the 100 m corridor was a better predictor of ecological

health was most likely due to the demonstrated effectiveness of riparian buffer zone s in removing pollutants, especially nutrients, from stormwater inputs (both surface and subsurface flow). Studies have shown that buffer zone widths of up to 60 m are sufficient to reduce the

nutrient lo ad by up to 95% before reaching t he stream (Peterjohn and Corell

, 1985). Additionally, buffer zones in the Coastal Plain areas are the most effective in retaining nutrients because of gradual slopes, permeable soils, and the abundance of roots that enter the shallow ground water zones (Lowrance

, 1997). Since phosphorus is typically found bound to sediments, riparian zones retain most of the incoming phosphorus by capturing sediments. Similarly, nitrate in shallow ground water beneath riparian zones was removed by 85 to 90%

due to plant uptake and denitrification in riparian zones 50 to 70 m wide (Lowrance

, 1992 ; Jordan et al.

, 1993 ; Jacobs and Gilliam

, 1985 ; Lowrance

, 1997).

While numerous studies have concluded that buffer widths of 50 to 70 m are suff icient to reduce stormwater nutrient loads to streams by as much as 95%, additional buffer width will provide additional protection to a waterbody. Based on these literature findings and the better correlations with biological health described above, FDEP concluded that a n LDI calculated using a 100 m corridor is an appropriate ly rigorous method of selecting candidate benchmark sites with minimal human disturbance and healthy biological communities.

As discussed in Appendix A

, the LDI was specifically desi gned as a measure of human disturbance. LDI values less than or equal to 2.0 within the 100 m buffer area indicate very minimal levels of human disturbance. Numerous studies and evaluation have demonstrated, across multiple waterbody types and taxonomic groups, that the LDI is an accurate predictor of biological health

— i.e., healthy

, well

- balanced biological systems are much more likely to occur at sites with low LDIs ( ≤ 2.0) than at higher disturbance levels (Fore

, 2004 ; Niu

, 2004 ; Brown

and Reiss

, 2006 ; Fore et al.

, 2007 a ). Furthermore, it has been demonstrated that a LDI of 2.0 is a consistent and conservative biologically significant breakpoint that can be used to distinguish

benchmark conditions from potentially disturbed areas.

Although it would be ideal to incorporate direct measures of biological health into the selection

of benchmark sites, paired nutrient and biological data were not available for all sites in the peninsula bioregion. A ppendix A provides a more detailed discussion of the LDI and its use at

select benchmark sites. Since it has been demonstrated that the LD I is highly correlated with multiple measures of biological health, selecting benchmark sites based on a n LDI threshold less than or equal to 2.0 is a conservative and ecologically reliable method.

The initial set of candidate benchmark sites in the peni nsula bioregion, with available nutrient data of known quality and LDI values less than or equal to 2.0, identified by FDEP consisted of 379 sites distributed among 155 WBIDs. These sites were considered candidate benchmark sites pending further review to demonstrate that they do in fact reflect low levels of human

disturbance and are representative of the region.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 23 

### 3. **4.2 Additional**  **Benchmark Site Evaluation** 

T he candidate benchmark site list developed from the LDI was then further assessed to ensure
that th e final set consisted of only minimally disturbed sites capable of supporting healthy

, well

balanced biological communities. And due to the nature of nutrients, it is also necessary to confirm that downstream biological communities are free from any impac t of transported nutrients at these upstream levels. The following assessments were designed to capture recent

land use changes a nd exclude sites that m ight not support the designated use

— i.e., sites within impaired waterbodies:

**•** Sites located within wat erbodies (WBIDs) placed on the Verified 303(d) L ists as impaired for nutrients or DO , where nutrients were identified as the causative parameters, were excluded as benchmark sites. Additionally, sites within WBIDs placed on the Verified or Planning 303(d) L ists for biological impairments, regardless of cause, were excluded from the benchmark population.

**•** It should be noted that

, since the benchmark sites exhibit low LDIs and human disturbance, WBIDs identified as impaired for DO with factors other than nutr ients as the cause likely represent natural conditions for those sites. Further, moderate

DO excursions below Florida’s current criteri on of 5.0 mg/L have not been associated with any adverse biological impacts. Therefore, such sites were not initially ex cluded from the benchmark dataset for nutrient threshold development

. However, FDEP further evaluated these sites us ing the Stream Condition Index ( designed to measure hea lthy, well balanced communities) to ensure DO was not

an adverse issue. For example , despite the naturally low dissolved oxygen at the Middle Prong of the St. Marys River at SR 125 (measured at 2.7 mg/L during the benchmark study) the SCI score was in the “ Exceptional ” category, exhibiting a n unusually diverse assemblage of sensitive inv ertebrates and indicating the site is clearly meeting its Class III designated use

.

**•** The low level of human disturbance of every candidate site was confirmed via a review of recent (2004) high

- resolution (1 m ground resolution) aerial photographs.

This rev iew consisted of searching the photos for recent land clearing or development, with particular emphasis on identifying any disturbance that

encroached into the 100 m buffer area used to calculate the LDI. S ites not representative of freshwater streams ( e. g ., tidally influenced or channelized) in the peninsula bioregion were also excluded.

**•** Twenty

- seven sites were excluded based on the review of aerial photographs. Ten of the excluded sites appeared to be within canals or channelized streams and

therefore were not considered representative of a minimally disturbed stream

condition. An additional 7 sites were excluded because they were potentially estuarine or tidally influenced based on proximity to the coast and a subsequent review of specific conductanc e data. All potentially estuarine sites routinely had specific conductance levels above 1

, 275 m icromohs per centimeter ( μmho/cm ) and episodic values above 4

, 500 μmho/cm. A conductivity of 4

, 500 μmho/cm is approximately equivalent to a chloride concentrat ion of 1,500 mg/L , which is used in Florida as the threshold between predominantly fresh and marine waters.

**•** FDEP District staff familiar with streams within their area of the state were asked to provide feedback on the list of candidate benchmark sites. Specifically, they were presented with the following information and question:

“ For ongoing nutrient criteria development, we are identifying sites with benign land uses in their upstream watershed (LDI < 2) to define the reference condition.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 24 Ken Weaver has produced the attached table of low LDI peninsular reference sites. Can you please look over the list to determine if there are any human activities at particular sites, which may not have been captured by the LDI

, that would disqualify the site from b eing used to define "reference" for nutrient criteria? ”

Twenty

- two peninsula pilot study sites were excluded from the benchmark set based on feedback and best professional judgment comments provided by District

staff. S taff identified additional channeliz ed streams, estuarine sites, and potentially disturbed sites. It should be noted that all the excluded sites were previously identified and confirmed as having a low LDI. In some cases

, staff identified potential point source discharges or localized dist urbances ( e.g ., cattle in

a stream) that may not have been captured in the LDI calculation. In other cases

, sites were excluded because the reviewer was aware of moderate to high levels of development in the watershed that were outside the 100 m buffer bu t potentially had an indirect ( e.g ., ground water) or minor effect on stream conditions; however, the sites may still be representative of low human disturbance levels

. The

exclusion of these potentially disturbed sites represents a conservative component

of the FDEP approach designed to ensure that the benchmark set consists solely of sites with low human disturbance levels that are supporting the designated use.



### 3. **4.3 Field Evaluation of**  **Peninsula Bioregion Benchmark**  **Stream Sites** 

In February 2007

, FDEP initiated an intensive field study of the candidate p eninsula bioregion

benchmark sites to provid e additional assurance that the sites truly supported health y

, well

balanced aquatic communities and had low human disturbance levels

. A subset of the popula tion of candidate benchmark sites was selected for additional review

, with the objective of building additional confidence in FDEP ’s extensive multi

- step validation process for identifying

benchmark sites. B iological data were collected with the objective of confirming that the sites did in fact support healthy

, well

- balanced biological communities and to demonstrate that an upper percentile ( i.e ., 75 th to 95 th percentile) was protective o f this biological community.

Experienced FDEP staff visited a tota l of 30 candidate benchmark sites, representing 26 WBIDs, between February 5, 2007

, and March 7, 2007, and assessed then for inclusion in the

final set of benchmark sites. The candidate benchmark sites evaluated in this study were initially selected using an LDI less than or equal to 2.0 and other assessments described above. Study sites were selected to cover the range of phosphorus concentrations exhibited by the population of candidate benchmark sites. S ites were grouped by their geometric mean TP

con centrations for the period of record (sites with means ≥ 90, < 90

- 60, and < 60 **μ** g/L )

. At least

10 site s within each concentration range were visited and evaluated during this study. Overall, long

- term geometric mean TP concentrations a t study sites range d from 30 to 140 **μ** g/L

, and long

- term geometric mean TN concentrations ranged from 0.6 to 2.1 mg/L

. S ites were also selected to be representative of most of the WBIDs in the candidate benchmark dataset. The site with the most extensive and longest period of record was selected to represent the WBID.

Site evaluations included a survey of anthropogenic inputs and surrounding land uses. The survey included both an on

- site inspection of the stream channel at least 200 m upstream of the sample point and a d riving tour of accessible areas in the watershed upstream of the sampling

site . Field investigations of the watersheds were guided by high

- resolution aerial photographs taken in 2004 and maps of the entire drainage basin. Investigators made observations concerning potential human disturbances in the watershed that might affect conditions within a given stream.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 25 Additionally, experienced staff characterized the sites using both FDEP ’s standard HA and

H ydrologic Modification S coring system s as objective me asures of human disturbance. FDEP biologists routinely calculate the HA index whenever stream macroinvertebrate samples are collected (FDEP, 200 8 ). The index evaluates substrate condition and availability, water velocity, habitat smothering ( e.g ., by san d and silt), channelization, bank stability, and the width and condition of riparian vegetation. The H ydrologic Modification S coring system was originally developed to support the development of Florida’s SC I and is scored based on knowledge of

water remo val, ditching and draining

, control structures, impervious surfaces , and hydrographs for the sites under evaluation (Fore

, 2004 ; Fore et al.

, 2007 a ).

At each site, t rained and experienced FDEP staff also collected and analyzed the biological, chemical, and physical parameters listed below following standard FDEP SOPs : ( http://www.dep.state.fl.us/labs/sop ). Water levels were evaluated both by reviewing hydrographs from the given stream or other streams in the general vicinity and by visual inspection of the stream habitats. Biological samples ( e.g

., SCI ) were not collected if, based on the judgment of the experienced investigator, a majority of the aquatic habitat was exposed to the air rather than being inundated.

Bioassessment s could not initially be conducted at 17 out of the 31 sites visited due to protracted drought conditions prior to and following the study. However, significant rainfall occurred in August, 2008 (Tropical Storm Fay), and FDEP sta ff conduct ed f ollow

- up bio logical assessments during December 2008 at the previously dry or low flow sites

. Sampled
parameters were selected both to verify the benchmark status of candidate sites and to support anticipate d future efforts such as statewide numeric nutrient criteria and biological index ( e.g

., RPS , periphyton index) development.

It should be no ted that no calibrated interpretative tool exist ed for the periphyton parameters when these data were analyzed ; therefore

, t he interpretation of res ults was primarily qualitative.

Methods for the RP S are still under development and no interpretation framework for the method currently exists ; th us, RPS results have not yet been evaluated . The RP S may be used as a response variable in the future to he lp refine nutrient thresholds , after more data have been

collected and benchmark expectations have been established.



### 3.4.3.1 Parameters Monitored During the Survey

Information acquired during the site and watershed evaluations was used to provide final

con firmation that the remaining candidate sites were in fact representative of the benchmark stream condition for the bioregion. Taken together with the LDI and other screening criteria, the results of the peninsula benchmark stream survey provide an extreme ly high level of confidence that FDEP’s benchmark set represents a low level of human disturbance that is supportive of the designated use, and these facts are documented in the benchmark site summaries ( Appendex C ) attached as separate documents. Table 4 lists the parameters monitored during

the peninsula bioregion benchmark stream survey

.



### Table 4

. Parameters m onitored during the peninsula bioregion benchmark

survey
Biological Parameters Chemical and Physical Parameters

**•** S CI **•** T P

**•** R PS **•** Nitrite + Nitrate

**•** Natural S ubstrate P eriphyton ( i.e., periphyton taxonomy) **•** T KN

**•** AmmoniaState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 26 **•** HA **•** Color

**•** Chlorophyll a **•** Turbidity

**•** Phaeophytin **•** Specific Conductance ( in situ )

**•** Algal Growth Potential (AGP) **•** D O ( in situ )

**•** pH ( in situ )

**•** Water Temperature ( in situ )

Although FDEP staff were unable to collect biological samples at some sites due to low water conditions, the available data indicate that the benchmark sites support healthy

, well

- balanced populations of flora and fauna even at nutrient concentrations above the 90 th pe rcentile of the

be n chmark distribution ( Figures 5 and 6 ). Exceptional biological communities (SCI ≥ 68 ) were found at sites with TP concentrations as high as 350 **μ** g/L and long

- term mean concentrations up to 128 **μ** g/L. Similarly, e xceptional biological com munities (SCI ≥ 68 ) were found at sites with

TN concentrations exceeding 1.7 mg/L. After this preliminary analysis was completed, additional biological and water quality data were collected at the sites that could not initially be sampled due to low wate r (see Appendix C).

Therefore, it can be confidently concluded that TP concentrations at least as high as the 90 th
percentile, which is derived and discussed below, are protective of the natural populations of

flora and fauna in streams with low human dist urbance

. Furthermore, the percent composition of major algal taxonomic groups (phyla) were very similar across the range of nutrient concentrations investigate d ( Figures 7 and 8 ). The periphyton communities at all the sites were highly dominated by diato ms (Bacillariophyta)

, with low percentages of green (Chlorophycota) or

blue

- green (Cyanophytcota) algae. Additionally, taxa richness was high (40

– 66) at all

benchmark sites

, except for Robert’s Branch (SEM426LV).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 27 

### F igure 5

. Plots of SCI versus TP concen trations at sites visited during the

p eninsula benchmark s tream survey

The dashed vertical line in each graph is the 90 th percentile TP concentration of the benchmark distribution. Phosphorus values are given as both the sample concentration on the S CI c ollection date (A) and the period of record geometric mean (B) for the site. SCI values of 68 or above are considered to be indicative of an exceptional biological community, while values to 35 are considered healthy and well

- balanced (Fore et al.

, 2007 a)

. Values below 35 are considered impaired. The slopes on the regression lines are not significantly different from 0

, indicating that there is no relationship between TP and SCI within this concentration range.



### Geometric Mean Total Phosphorus (mg/L) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14SCI



### 0 20 40 60 80 100 

### Total Phosphorus (mg/L) 0.0 0.1 0.2 0.3 0.4SCI



### 0 20 40 60 80 100

Exceptional

Healthy

Impaired y = 2.5x + 67.5

R 2 = 0.0004

p =0.956



### Exceptional

Healthy Impaired

y = -16.018x + 69.142

R 2 = 0.015

p =0.908 A.

B.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 28 

### Figure 6. Plots of SCI versus TN concent rations at sites visited during the peninsula benchmark stream survey

The dashed vertical line in each graph is the 90 th percentile TN concentration of the benchmark distribution. Nitrogen values are given as both the sample concentration on the SCI coll ection date (A) and the period of record geometric mean (B) for the site. SCI values of 68 or above are considered to be indicative of an exceptional biological community, while values to 35 are considered healthy and well

- balanced (Fore et al.

, 2007 a

). Values below 35 are considered impaired. The slopes on the regression lines are not significantly different from 0

, indicating that there is no relationship between TN and SCI within this concentration range.



### Geometric Mean Total Nitrogen (mg/L) 0.0 0.5 1.0 1.5 2.0SCI

0 20 40 60 80 100 

### Total Nitrogen (mg/L) 0.0 0.5 1.0 1.5 2.0SCI

0 20 40 60 80 100

Exceptional

Healthy

Impaired y = -5.7x + 72

R 2 = 0.031

p =0.602

Exceptional

Healthy Impaired

y = -2.5x + 70.3

R 2 = 0.0033

p =0.866 A.

B.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 29 

### Figure 7. Plots of percent ( A ) Bacillar iophyta, ( B ) Cryptophycophyta, and ( C ) Cyanophycota collected on natural substrates versus site period of record geometric mean TP concentrations

The dashed vertical line in each graph is the 90 th percentile TP concentration of the benchmark site distribu tion.Percent Bacillariophyta



### 50 60 70 80 90 100Percent Chlorophcota



### 0 2 4 6 8 10



### Geometric Mean TP (mg/L)

0.04 0.06 0.08 0.10 0.12 0.14Percent Cyanophytcota



### 0 5 10 15 20 25

C. A.

B.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 30 

### Figure 8. Plots of percent ( A ) Bacillariophyta, ( B ) Cryptophycophyta, and ( C ) Cyanophycota collected on natural substrates versus site period of record geometric mean TN concentrations

The dashed vertical line in each graph is the 90 th percenti le TN concentration of the benchmark site distribution.Percent Bacillariophyta



### 50 60 70 80 90 100Percent Chlorophytcota



### 0 2 4 6 8 10



### Geometric Mean TN (mg/L)

0.50 0.75 1.00 1.25 1.50 1.75Percent Cyanophcota



### 0 5 10 15 20 25

C. A.

B.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 31 

### 3.4.4 **Statistical O**  **utlier A**  **nalyses**

An analysis of statistical outliers was performed to identify data and sites that were uncharacteristic of the general peninsula dataset used to derive nutrient criteria for the bioregion. This was done to help evaluate the dataset and prevent the nutrient criteria for the bioregion from being unjustifiably biased by a small number of sites that are not representative of the peninsula bi oregion (including data f rom area s affected by significant natural phosphate deposits).

The outlier analysis was performed using standard statistical methods by defining the outlier

limit as:

75 th percentile + 1.5 * Interquartile Range

Data points identified as outliers were excl uded from the dataset. In addition

, if more than 50% of the data for an individual site were identified as outliers, then all the data for that site were

excluded

, since the remaining data for the site cannot be considered representative of the site.



### 3.4. **5 Calculation of Annual**  **WBID Geometric Mean** 

A number of the benchmark waterbodies were sampled numerous times and by different agencies. The sampling sites used by the different samplers we re often located within several

hundred meters of each other. The refore, to avoid biasing the analyses toward the larger waterbodies with multiple sampling sites near to each other, the station level data were aggregated by WBID.

The data were also aggregated over time through the calculation of the annual WBID geomet ric mean. An annual period was selected because e levated nutrient levels are not acutely toxic in the aquatic environment; instead, their effects are chronic and cumulative over time. Nutrient concentrations typically var y over time and exhibit a log

- nor mal distribution in the aquatic

environment. Therefore, instantaneous criteria are not generally considered practical or appropriate for nutrients, and are better expressed as an average over a longer period. Additionally, the geometric mean is often use d to provide a more accurate representation, rather than an arithmetic mean, of the central tendency of positively skewed data ( e.g ., log

- normal), such as nutrients. The use of the annual geometric mean mutes short

- term variability and provide s a more rel iable, long

- term value for assessing the nutrient status in aquatic

environments.



### 3.4.6 **Defining Nutrient Limits**

A key issue of the pilot study was the selection of the appropriate percentile to use for the

numeric criterion. Since benchmark sites are opt imally functioning systems supportive of the designated use , selecting a percentile at the upper end of the distribution ( i.e ., 90 th to 95 th
percentile) as a criterion is an appropriate decision. This method establishes the range of

nutrients characterist ic of these biologically healthy sites , with a necessary allowance for

confidence in protection

, balanced against the possibility of only 5 to 10 % of these biologically healthy sites being po tential ly misidentified as impaired. T he range of nutrient conce ntrations

associated with benchmark sites is considered to represent nutrient levels expected in areas

with low levels of human disturbance

. A n upper percentile distribution of the benchmark site population will yield an ecologically justifiable, inherent ly protective criterion.

Due to the high degree of confidence in the benchmark sites derived through FDEP’s multi

- step selection process

, FDEP used the 90 th percentile annual WBID geometric mean TN and TPState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 32 concentrations for benchmark sites (grouped by WB ID) in the peninsula bioregion as the basis for protective numeric nutrient criteria for streams in the bio re gion. T he extensive verification of

the benchmark sites provided a high level of confidence that the resulting benchmark

distribution truly repres ented low levels of human disturbance that fully achieved the designated

use of the streams ( supporting healthy populations of aquatic flora and faun a )

. L ocal use support can be confirmed via coincident nutrient and bioassessment sampling

, with the hypoth esis that nutrients associated with these minimally disturbed upstream reaches will be inherently protective of downstream waters. The “proof of concept” that downstream conditions

still support healthy, well balanced communities will be demonstrated by th e Longitudinal Study

.

The use of the 90 th percentile is further supported by the fact that numerous waterbodies with phosphorous concentrations up to and including this level of phosphorus were shown to support healthy populations of aquatic flora and faun a and fully achieved the ir designated use. Further,

to ensure that the data used were of the highest quality, only data from sources in which the quality of the data could be verified were utilized in the analysis. The application of this method gives ca lculated criteria of 1.7 m g/ L for TN and 113 **μ** g/L for TP

.



### 3.4.7 **Ongoing and Future Efforts** 

During the fall and winter of 2008, FDEP conducted an intensive benchmark site validation process, developed and tested during the peninsular pilot study , to candida te benchmark sites in the panhandle and northeast bioregions. In addition , peninsular benchmark sites that could not be previously sampled due to low water levels were revisited in December 2008

. F ield

reconnaissance and data collection trips for all ben chmark sites were completed in December

2008. These statewide site evaluations were conducted for the following reasons:

(1) To confirm and build confidence that the benchmark sites are a ffected by only low levels of human disturbance;

(2) To support the use of an upper percentile nutrient concentration inclusive of the

benchmark distribution as a numeric nutrient criterion ; and

(3) To confirm that healthy

, well

- balanced biological communities (flora and f auna) are protected and maintained at or below a criterion es tablished at the selected upper percentile ( e.g ., 90 th percentile)

.



## 3.5 Stressor I dentification Study

Historically, FDEP has focused on water quality as the predominant means for assessing water body integrity ( i.e ., impairment status). Through the use o f EPA Section 319 funding, FDEP has developed biological assessment tools ( e.g ., Florida’s SCI

, BioReconnaissance [ BioRecon ]

, and

LVI ) and habitat assessment procedures as additional means of identifying impairment, especially related to nonpoint source is sues

. Although bioassessments are useful in determining biological impairment, they do not identify the cause of the impairment, which is required under the Florida Watershed Restoration Act before listing a water body as impaired

. Currently, a Best Profe ssional Judgment methodology is used to identify the pollutant of

concern. The development of a statistically based model(s) for the identification of impairment causes would improve the effectiveness and defensibility of FDEP decisions.

Additionally, ide ntifying the primary causative factors most influential in contributing to biological

failures would allow FDEP to focus its limited resources on properly mitigating the responsible stressor(s). Therefore, a legally defensible procedure to determine the c ausative factor(s) is

needed

. EPA has developed procedures for stressor i dentification ( e.g

., CausalState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 33 Analysis/Diagnosis Decision Information System [ CADDIS ] ) that are useful only for selected sites after fairly substantial data collection efforts. Florid a plans to build on these stressor identification concepts to develop a statistical model or multiple models (Statewide Stressor

Identification Model [s] ) that incorporates the major nonpoint source stressors widespread in

Florida:

**•** Hydrologic modification ;

**•** Habitat alteration; and

,

**•** Water quality issues ( e.g ., nutrients, sediments, and biochemical oxygen demand [BOD] ).

The d evelopment of a calibrated statewide model would prevent Florida from having to perform

EPA

- style

, site

- specific stressor identificat ion studies at all biologically impaired sites (a cumbersome and expensive task). It is anticipated that the Statewide Stressor Identification Model(s) will allow FDEP to streamlin e restoration efforts by identify ing the most pervasive human nonpoint stre ssors in Florida.

The overall approach for this project will involve the assessment and collection of a complex suite of data in order to develop the Statewide Stressor Identification Model(s). Initial emphasis

will be on current FDEP tools used to mea sure the algal (periphyton and phytoplankton),

invertebrate

, and macrophyte community health of streams

, and EPA ’s list of common candidate causes, which include the following :

**•** Nutrient inputs,

**•** Flow alterations,

**•** Sediments,

**•** Metals,

**•** DO

,

**•** Temperature,

**•** Ionic s trength , and

**•** Habitat assessment

.

FDEP plan s to use multivariate statistics to investigate the relationships between all available physical, chemical

, and biological data, evaluating significant variables and their relative influence on a system. An itera tive process will be employed, consisting of data analysis and the exploration of conceptual models, with discovered relationships used as inputs for developing even more effective models. FDEP will pose a series of hypotheses (conceptual models) and then statistically examine the relationship between stressor(s) and responses. Example s of hypotheses include the following :

**•** Turbid runoff, leading to sediment smothering, will cause low SCI scores ;

**•** High nutrients, coupled with sunlight and sluggish flow, wil l lead to excessive periphyton in habitats and reductions in periphyton community and invertebrate

health ; andState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 34 **•** Extreme hydrologic fluctuations, regardless of ambient water quality, will lead to low SCI scores, etc.

Additionally, biological Stressor Indice s ( i.e ., response signature metrics) may be developed that provide better resolving power in identifying specific types of stress. The Stressor Identification

Model (s) will be constructed once significant stressor relationships are known. The model(s)

wi ll identify the relative influence of major stressors in contributing to biological impairments. From this more complex model, FDEP will investigate the possibility of a simplified model with reduced inputs. Finally, EPA

- style stressor identification wil l be performed at a number of sites to verify the model(s).

The tasks associated with this project are anticipated to include but are not necessarily limited

to the following :

**• Analy**  **ze current data:**  Review water quality and biological data and identification of data gaps for future data collection;

**• Evaluate and modify Stressor Indice**  **s as necessary :**  Investigate response signature metrics for the construction of Stressor Indices;

**• Identify possible conceptual model(s):**  Determine conceptual model(s) designed to predict the relationship between the stream Stressor Index and causative variables;

**• Collect additional data:**  Collect data to fill data gaps identified in previous tasks;

**• Develop Stressor Identification Model:**  Develop appropriate model(s) based on

wa ter quality and biological data; and

**• Validate Model(s):**  V alidate model (s) with an independent dataset and verify by comparing the model(s) output with the output of deterministic stressor

identification (e.g., CADDIS)

.

Once this model is developed, it ca n be used to better quantify the relationship between nutrient

levels and stream health

, given all the different factors influencing aquatic life.



## 3.6 Development of the Stream Periphyton Index

FDEP recently develop ed and validat ed a multimetric index bas ed on periphyton samples from

Florida streams (th e SPI) , b ut the index has yet to be calibrated . The following brief ly descri bes this ongoing process.

(1) **Evaluat e algal distributional patterns:**  FDEP identif ied patterns of taxonomic distribution for algal sp ecies. If needed, metrics will be calibrated separately within each region to e nsure that the final index value represent s the same level of biological condition independent of natural features.

(2) **Develop gradients of human disturbance :**  The HDG combine d me asures of water quality, habitat condition, hydrologic condition, and LDI. In addition, a multimetric nutrient index based on probabilistic data was developed to combine

measures of in

- stream nutrient concentrations.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 35 (3) **Identify and calculate candidate metr ics for stream algae**  **:** Appropriate biological metrics were identified and calculated from published taxa lists for both diatom and nondiatom (soft) algae taxa.

(4) **Test taxa against the HDG :**  Using the HDG , this analysis test ed the response of

individual diat om and nondiatom taxa to an independently derived measure of site

condition. The Florida sensitive taxa and the very tolerant taxa metrics were identified using this process

. (5) **Test metric response to human**  **disturbance :**  FDEP test ed the association

between the metrics and the HDG and the nutrient index. Metrics were evaluated for the influence of natural features such as stream size, latitude, and bioregion. After selecting the metrics with a reliable response to disturbance, the redundancy

of individual metrics was evaluated. Effective metrics that will be incorporated into the SPI include the number of algal cells requiring high oxygen, the number of oligosaprobic cells, Van Dam’s T SI , the percent Florida s ensitive cells, and the percent Florida toleran t cells. Additional “soft algae” metrics are still be investigated.

(6) **Develop multimetric index :**  Metrics were converted into a final index which

scores from 0

- 100

. Stream classification was evaluated to determine whether metric scoring rules should compen sate for any underlying regional difference, such as pH

. The index was tested against the HDG and outliers identified and

evaluated for additional sources of disturbance.

(7) **Validat e results**  **:** FDEP used an independent dataset to validate results from the

ini tial periphyton index analysis. The index and its component metrics were calculated for at least 50 new sites as an independent test of the observed algal response to disturbance.

(8) **Conduct p ower analysis**  **:** Using repeat visits, the percentage of change that the

multimetric index can detect was determined. FDEP also evaluate d the influence of repeat sampling for increasing the precision of stream algal assessments.

(9) **Calibrate the BCG:**  In conjunction with EPA

, in February, 2009 Florida is convening a panel of national periphyton and ecological experts to calibrate the
S PI via the B CG approach. It is anticipated that this may potentially provide a numeric target for the determination of an impairment threshold , which then would be used to establish protective nutrient criteria

.

It is anticipated that the resulting S PI will be an extremely useful response variable for determining impairment associated with nutrient enrichment in streams, and it may also be adopted as Biocriteria in Chapter 62

- 302

, F

. A

. C

. (wate r quality standards).



## 3.7 Downstream Effects of Nutrients in Selected Florida

River s /Estuaries (Nutrient Longitudinal Study)

FDEP initiat ed a Nutrient Longitudinal Study during the summer of 2008 designed to evaluate downstream biological responses to natu rally high nutrient levels. Biological responses to

excess nutrients can be separated in space and time from actual enrichment sources

— i.e., an adverse response to nutrients may occur well downstream from the actual enrichment. FDEP’s hypothesis is that w ithin systems with low levels of human disturbance and intact ecological

processes

, naturally high levels of nutrients can be assimilated into biota and sediment s without causing adverse biological responses

, including downstream estuaries

. The goal of t his study isState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 36 to demonstrate that nutrient concentrations representative of the upper portion of the

benchmark site distribution actually support the designated use of downstream reaches

.



### 3.7.1 **P roj**  **ect Ob jectives** 

The objectives of the s tudy were as follo ws :

(1) Collect physical, chemical, and biological data throughout the length of selected Florida river/estuary systems to establish the relationship between nutrient levels and adverse biological responses, including the most sensitive (generally downstream) reaches ; and

(2) Analyze the resulting dataset as one line of evidence in FDEP’s effort to establish numeric nutrient criteria, particularly relating to the protection of downstream

waters.



### 3.7.2 **Project Description**

Th e study focused on relating the effects o f nutrients on various biological systems, from upstream to downstream, including the most sensitive areas, which typically are slowly flowing

lower reaches or estuaries. Two systems were studied : Waccasassa River and E stuary and
Steinhatchee River and / E stuary

.

S emiannual sampling was carried out for the biological components and water quality
parameters

. The first sampling occurred in summer 2008, and the second was done in January

2009. All samples were collected according to F DEP

- SOP

- 001/01. The FD EP Bureau of Laboratories in Tallahassee will analyze water, biolog ical, and sediment samples.

The following was performed at sites where appropriate (dependant on salinity, etc.) ; t he location of sites in each system w as established after a reconnaissance trip :

**•** Water Chemistry (TKN, TP, ammonia, nitrate

- nitrite, turbidity, chlorophyll a, color,

TOC , T SS ) (monthly) ;

**•** Meter Readings ( DO , specific conductivity, pH, and temperature) (monthly) ;

**•** Phytoplankton C ommunity C omposition (monthly) ;

**•** Microcystin A nalyses (if warranted from results of algal ID ) ( to be determined) ;

**•** S CI (quarterly) ;

**•** H A (quarterly) ;

**•** Percent Canopy Cover (quarterly) ;

**•** R PS (quarterly) ;

**•** Qualitative Periphyton Collection (quarterly) ;

**•** Linear Vegetation Survey (quarterly) ;

**•** Sediment N utrients (semiann ually) ;

**•** Sediment N utrient F lux E xperiments (semiannually) ; and

**•** Hydrologic Modification Scoring (once)

.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 37 Both systems were selected to represent conditions of relatively low human disturbance

, especially with respect to nutrient enrichment. The nutrient re gime at the Waccasassa ranges

toward values that are less than the p eninsular benchmark site distribution average, while the Steinhatchee ranges from near the average to the upper end (90 th percentile) of the benchmark site nutrient distribution average.

S ince the objective of the study is to emphasize the effects of nutrients on biota, attempts were made to minimize or account for confounding factors during site selection. Habitat suitability (substrate diversity and abundance), flow, and length of inunda tion were examined when deciding appropriate sites to sample. A n H A , Hydrologic Modification Score, and Percent Canopy Cover determination was performed at all sites to adequately characterize these important variables. Additionally, staff carefully asse ss ed the existing and antecedent flow

conditions of each site to determine that they were appropriate for the purpose of th e study. There were some issues associated with extremely low flow during the first field sampling effort

. It is anticipated that w inter rains have increased water velocities, and those conditions will be reflected during the January 2009 sampling event.



### 3.7.3 **Project Outcomes**

FDEP hope s that this work will provide evidence that criteria developed using the benchmark

distributional ap proach are protective of downstream waters. T he knowledge that biota in downstream waters are sufficiently protected would help in e stablishing numeric nutrient

thresholds or criteria using the benchmark distributional approach. Furthermore, it is antici pated

that th e study will help to elucidate the effects of other variables ( e.g ., habitat, flow, canopy cover) on the expression of nutrients. FDEP will complet e sample collection in January 2009

and will analyze/synthesize the results in an additional si x to eight months.



## 3.8 Nitrate

- Nitrite Analysis in Streams/Spring Runs

Florida springs are highly valued for their aesthetic and recreational attributes. The state has

a pproximately 600 springs, which are visited by millions of people each year for swim ming and boating because of their beautiful, clear waters. Human activities during the past 4 0 years have

resulted in increased nitrate

- nitrite concentrations in many springs, and anecdotal evidence suggests that this has contributed to the currently obse rved nuisance plant and macroalgal

accumulations in many springs . FDEP recently evaluated nitrate trends at 22 Florida springs

and determined that the mean nitrate

- nitrite concentration in the 1960s was about 0.2 mg/L

, wh ile the average is currently aroun d 1.0 mg/L.

Multiple lines of evidence indicate that reducing nitrate

- nitrite concentrations in springs should

substantial ly reduce macroalgal growth rates (Stevenson et al

. , 2007 ; Niu and Gao

, 2007) . In turn, the reduced growth rate is expected to result in the reduced frequency, intensity, and duration of nuisance macroalgal growths in spring systems. Both nitrogen and phosphorus reductions in Florida springs should limit the growth of macroalgae species and subsequently reduce macroalgal accumulations. Such reductions should be effective as long as target concentrations ( e.g.

, nutrient criteria) are below nutrient concentration thresholds that promote excessive algal growth.

In almost all springs, however, nitrogen ( i.e ., nitrate

- nitrite) reductions may be the only practical restoration strategy because natural phosphorus concentrations ( those not influenced by humans) are generally higher than the levels necessary to constrain algal growth. Results from experimental and in situ studies were used to establish the nitrate

- nitrite concentrationState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 38 necessary to prevent biological imbalances ( i.e. , to restrict the growth and accumulations of nuisance macroalgae and to preserve the native periphyton community structure).

The most accurate and conservative exp erimental results, those from micro

- centrifuge tube experiments, suggest that nitrate concentrations less than 0.230 mg/L are needed to slow the growth of Lyngbya wollei . Similarly, to reduce the growth of Vaucheria under laboratory conditions, nitrate co ncentrations below approximately 0.261 mg/L would be required (Stevenson et al.

, 2007)

.

The r esults of periphyton field surveys conducted at a large number of spring systems indicated

that nitrate concentrations would need to be reduc ed below the observe d 0.454 mg /L nitrate

ni trite threshold to reduce the nuisance abundance and cover of Vaucheria sp . in Florida springs (Pinowska et al.

, 2007) . Since the 0.454 mg /L threshold represents the lower range of nitrate concentrations for sites with excessive alg al growth and cover, an appropriate safety margin would need to be applied to turn the threshold into a protective criterion.

In addition, nearly a decade of scientific results from periphytometers deployed in the spring

dominated Suwannee, Santa Fe, and W ithlacoochee (north) Rivers clearly indicated an imbalance threshold (significant biomass increases and alterations in taxonomic community structure) at 0.441 mg/L of nitrate

- nitrite. A margin of safety, derived from an analysis of the variability in the nitrate

- nitrite concentrations in this system, resulted in the final 0.3 5 mg/L

nitrate

- nitrite criterion.

Based on the best, most comprehensive scientific data currently available, this criterion provides

FDEP with reasonable assurance that imbalances o f aquatic flora are unlikely to occur below

this level. The data also indicate that imbalances do occur at nitrate

- nitrite concentrations near 0.45 mg/L and above. Therefore, a nitrate

- nitrite criterion of 0.3 5 mg/L for spring s was proposed during the on going triennial review , which was initiated in July 2008.



## 3.9 Lake Algal and Macrophyte Response

FDEP intends to evaluate both algal and macrophyte response thresholds in Florida lakes.
S taff presented preliminary conditional probability analys es betwee n the LVI and TP and TN

concentrations at the February 25, 2008

, meeting of the Nutrient Criteria TAC ( Figures 9 and

10 ). The analysis with phosphorus showed that the probability of occurrence of an LVI score less than 37 (the impairment threshold) increa sed up to a lake TP concentration of approximately 50 **μ** g/L

, at which point the probability of impairment leveled off

. However, there was significant uncertainty at concentrations above 45 **μ** g/L, given the small sample size for

lakes with concentrations abo ve this level . Similarly, the probability of occurrence of an LVI less than 37 increased with increasing TN concentrations.

These preliminary analyses demonstrate a likely relationship between in

- lake nutrient s and macrophyte community health. Because the paired LVI and nutrient dataset is currently limited, particularly in lakes with TP concentrations above 45 **μ** g/L, FDEP conducted additional LVIs with paired nutrient samples during the summer and fall of 2008

. A subset of lakes previously sampled as part of the state’s randomized status and trends monitoring was targeted for LVI and water quality sample collect ion. Although samples were apportioned across the entire range of nutrient concentrations, priority was given to lakes with TP co ncentrations between 45

and 200 **μ** g/L in an attempt to reduce the uncertainty ( i.e ., confidence interval width ) by increasing s ample size in this range of nutrient concentrations

.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 39 FDEP also intends to evaluate algal responses to nutrients. Initially, the evaluation will be based on relationships between nutrients and chlorophyll a concentrations. Secondarily, the

evaluation will look for relationships between nutrients and metrics contained in the L VI

. These analyses will include the evaluation of regression models as well as conditional probability using ecologically significant thresholds. Conditional probability analysis may include a joint analysis

of the probability of exceeding either chlorophyll a or LVI impairment targets , since any given lake may be either algal or macrophyte dominated. Community

- base d analyses may follow if necessary and pending the development of a c alibrated lake phytoplankton index.



## 3.10 Recreation

- Based Criteria

The University of Florida LakeWatch Program conducted a study that correlated Florida lake residents’ aesthetic perceptions with simultaneously measured nutrient and chlorophyll a data.

In the study, residents perceived that lake water was less conducive to swimming and aesthetic enjoyment when chlorophyll a concentrations ranged from approximately 17 to 22 **μ** g/L. FDEP may potentially use such information as a line of evidence when establis hing appropriate lake chlorophyll a thresholds; however, it is not pursuing additional studies of this nature at this time.



### Figure 9. Probability of observing LVI value less than 37 in Florida lakes if specified TP concentration is exceeded

Dashed lines are 90 % confidence intervals from bootstrap estimation.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

X
c Total Phosphorus Concentration (mg/L)Probability LVI < 37 | Xc Raw Data Probability

90% C.I.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 40 

## 3.11 Application of Benchmark Distributional Approach to Lake s

The majority of FDEP’s nutrient criteria efforts to date have focused on streams; however, much of the data and information necessary to apply the benchmark distributional approach to lakes currently exists within the state’s extensive database. If needed, FDEP will have the option of applying an approach to lakes using a process similar to that developed for streams. The approach will include the same multi

- step validation process incorporating land use evaluations ( e. g., LDI, recent aerial photographs, and field reconnaissance) coupled with confirmations of healthy biological communities using the LVI.

Because of the successful calibr ation of the LVI, FDEP is close to developing response

- based nutrient criteria for lakes. Therefore, the benchmark distributional approach will only be pursued as a secondary line of evidence and will be used only to derive criteria if the recreational

- ba sed and algal and macrophyte response evaluations fail to identify significant relationships with

nutrient enrichment.



### Figure 10

. Probability of observing LVI value less than 37 in Florida lakes if specified TN concentration is exceeded

Dashed lines are 90 % confidence intervals from bootstrap estimation.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

0 0.5 1 1.5 2 2.5 3 3.5 4

X
c TN Concentration (mg/L)Probability LVI < 37 | Xc Raw Data Probability

90% C.I.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 41 

## 3.1 2 Approach for Estuaries

Florida estuaries tend to be dynamic, many with widely varying water residence times and highly fluctuating salinities, and some with transparency regimes dominated by river ine color inputs. Since a direct comparison between any two specific estuaries is difficult, the “ EPA

reference waters” approach appears to be less practical than the “dose

- response” approach in

estuaries. In the approach to estuarine nutrient criteria d evelopment , FDEP is seeking to

establish empirical and other scientific relationships between nitrogen and phosphorus loads and response variables that represent a quality of water that supports a particular use. In doing so, those estuaries that are cur rently minimally disturbed will be protected from future adverse impacts a ssociated with nitrogen and phos phorus enrichment. Furthermore, criteria for both causal and response variables will provide a basis for improving water quality in those estuaries

cu rrently impacted b y excessive nitrogen and/or phos phorus loads

.

FDEP currently intends to utilize its existing TAC

— coordinated with the Florida Oceans and
Coastal Council and the Gulf of Mexico Alliance (GOMA )

— and EPA to help develop nutrient

criteria for estuaries and coastal waters. FDEP is still evaluat ing whether to augment the TAC

with additional members or to convene a smaller working group with expertise in estuarine and coastal systems. FDEP initiated the development of estuar ine nutrient criteri a at the beginning of 2008 and began a public process on June 5 and 6, 2008

, with an estuarine nutrient criteria development workshop ( http://www.dep.state.fl.us/water/wqssp/n utrients/tac_archive.htm ). The objective of this meeting was to discuss the state of nutrient science, research

, and monitoring

for Florida’s coastal waters

, as well as potential numeric criteria derivation methods. FDEP invited scientists who had perfo rmed research on selected Florida estuaries and asked that they do the following :

**•** Describe the system, including the hydrodynamics and sources and fates of nutrients;

**•** Describe the type, quality, community structure, areal extent, etc.

, of valued ecological attributes (biological communities), emphasizing those shown to respond to anthropogenic nutrient enrichment;

**•** Provide scientific evidence quantifying the relationship between anthropogenic nutrient inputs and adverse effects on biological communities; and

**•** Propose numeric targets needed for system protection or restoration, as well as demonstrate the bases for the nutrient targets.

Of the ten estuary studies presented, half focused on the relationship between nutrient loading (mostly nitrogen) causing exc ess algal growth (as measured by chlorophyll a production), which resulted in decreased transparency and

, consequently, light limitation/stress to SAV. In some estuaries, this complex relationship was established ; in others, there was a relationship betwe en nutrient loading directly on SAV (no chlorophyll issues) ; while in others, no relationship between nutrients and biological attributes could be quantified. In one instance, inorganic nutrients were elevated enough to foster h armful a lga l b looms (HABs) and concomitant declines in animal food webs, even though chlorophyll was low

.

From the workshop, it appears that Florida estuaries generally fall into one of three groups , as follows :

(1) Systems where nutrient dose

- response relationships are sufficiently un derstood to warrant proposing criteria (e.g., Tampa Bay, Perdido Bay, North Indian RiverState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 42 Lagoon (IRL) , Lower St. Johns River, and potentially Sarasota Bay). These systems have historically demonstrated nutrient issues, and many are recovering

due to resto ration efforts. Note that in many of these systems, the strongest relationship between nutrients and SAV response was based on loadings, not

concentrations. Time series data from these estuaries would be valuable in helping model dose

- response relationsh ips.

(2) Systems where factors other than nutrients appear to be more influential in defining biological community structure, making it currently difficult to propose scientifically defensible nutrient criteria (Caloosahatchee, S outh I RL , Pensacola Bay, parts of Florida Bay, and Charlotte Harbor). For these estuaries, some sort of reasonable assurance (e.g., from a model) that a particular nutrient regime protects the designated use would be needed.

(3) Systems that currently appear to be healthy and well

- function ing and a “maintain the status quo” approach for nutrients may be appropriate (e.g., Apalachicola, Apalachee, St. Andrews, Nassau/Amelia/St. Marys, Tolomato, Guana, Matanzas,

Ten Thousand Islands).

FDEP is particularly interested in an approach used by th e St. Johns River Water Management

District (SJRWMD) for the N orth I RL in which:

**•** SAV was related to a wat ershed loading regression model;

**•** Transparency depth targets to protect SAV photosynthesis in t he IRL ranged from

1.2 to 1.8 m ; and

**•** Turbidity, chlorophy ll a, and color targets were based on preventing a transparency reduction of greater than 10%.

Using a model by Valiela and Cole (2002), total allowable nitrogen load limits for each segment could be calculated, and it was estimated that the loading neede d to be below 20 kilograms of nitrogen per hectare per year ( kg N/ha/yr ) (based on water area) to protect SAV. A critical component is water residence time

.

The EPA National Nutrient Criteria Technical Guidance Manual for estuarine and coastal marine

wate rs recommended that appropriate response variables include chlorophyll, water clarity and other variables recognized in the scientific literature as responsive to nutrient inputs, including dissolved oxygen, seagrass or other biological components of the e stuarine ecosystem. FDEP expressed the desire to target nutrient criteria development to protect seagrass habitats, a valued estuarine resource throughout the State that supports particular uses. The scientific literature recognizes that the effects of n utrients on seagrass are well

- known, but also that these effects are largely indirect. To a first approximation, elevated nutrient loads enhance both phytoplankton production and growth of epiphytic algae on seagrass leaves. Together with

colored dissolve d organic matter and suspended particulates, these factors reduce water clarity and light availability for seagrass growth.

FDEP is currently working with EPA to gather the information necessary to develop a Florida

specific estuarine nutrient cause/effec t relationship, potentially similar to the Valiela and Cole (2002) model, but tested against, and potentially adapted to, Florida estuaries

. The following elements describe, in general, several critical information and data needs, computations and

evaluat ions that will be undertaken by EPA ’s Gulf Ecology Division (GED) and/ or EPA

contractors include the following :State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 43 **•** Estuary Delineation. EPA and FDEP will establish a common approach to delineating

the boundaries of estuaries and their watersheds in the State

, and to identifying the resulting estuaries for which nutrient criteria will be developed

.

**•** Nutrient Load Estimation. EPA and FDEP, with assistance from USGS, will develop a common approach to estimating monthly and annual nitrogen and phosphorus loads to each Florida estuary for a suitable period of record, including loads from atmospheric deposition, point and non

- point sources, and, if possible, from ground water and oceanic sources. In addition to loads, estimates of freshwater discharge and source wat er nutrient concentrations will be needed.

**•** Water Quality Database. EPA and FDEP will evaluate the suitability and representativeness of water quality variables within existing FDEP databases . Priority variables include: salinity, temperature, nutrients ( TN, TP, NOx, etc), dissolved organic matter, total suspended solids, Secchi depth, color, and chlorophyll a . Available data on

historical seagrass coverage across Florida will also be compiled.

**•** Empirical Analysis. EPA and FDEP will analyze and evaluate empirical relationships between causal and response variables for each estuary using appropriate computational/statistical methods. The evaluation will include analysis of cause

- effect relationships for all Florida estuaries combined, or some subset of est uaries based upon a defined criteria or categorization approach. For example, some Florida estuaries are naturally turbid due to a natural background of colored dissolved organic matter, whereas others lack significant natural turbidity. Moreover, some Fl orida estuaries naturally lack appreciable seagrass coverage. Efforts to identify and evaluate appropriate response variables that represent desired water quality and support designated uses will ensure that the proposed criteria are protective of all est uarine

waters.

FDEP also plans to adopt regional response variable nutrient criteria based on site

- specific thresholds developed for many of the larger coastal systems in the state ( e.g ., Tampa Bay, I RL

, Caloosahatchee, St. Lucie ) and subsequently derivin g causal variable criteria based on statistical relationships between these response variables and the causal variables. However, it should be noted that in many cases such relationships may not exist, as was the case in
Sarasota Bay. Under this scenario , FDEP may only propose response variable

– based criteria until the relationships are determined on a site

- specific basis

.

As a result of the state’s 1987 Surface Water Improvement and Management ( SWIM ) Act and

the National Estuary Program (NEP) , efforts t o develop nutrient

- related thresholds for many of

the state ’ s largest estuaries and coastal waters are well under way and are briefly described

below.

Tampa Bay Tampa Bay NEP has established c hlorophyll a targets for the different segments of the bay

based on a goal of restoring seagrass beds to 38,000 acres within the bay. The bay now supports 28,299 acres of seagrass. The Tampa Bay chlorophyll a targets were established

based on the effects of chlorophyll on light attenuation and ultimately on the depth of seagrass

occurrence. T N loading s were in turn related to c hlorophyll a concentrations, using a three

month lag time during the analysis. Ambient nitrogen concentration was not shown to directly affect light attenuation or seagrass condition.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 44 I RL an d Banana River

The I RL /Banana River Lagoon PLRG study set maximum loading targets for TN, TP, and TSS as a function of seagrass depth limits in the lagoon. The PLRG study found strong, negative correlations between watershed loadings of nutrients and TSS and the depth limit of seagrass. EPA proposed a TMDL in April 2007 based on the I RL /Banana River Lagoon PLRG, and FDEP proposed a state TMDL fo r the main stem of the Indian River and Banana River in fall 2008

.

Caloosahatchee and St. Lucie Estuaries

The No rthern Everglades and Estuaries Protection Program expanded the Lake Okeechobee Protection Plan (LOPP) requirements to the Caloosahatchee and St. Lucie River watersheds. This legislation created the Caloosahatchee and St. Lucie River Watershed Protection Program, which includes the development of Watershed Protection Plans for both rivers . Each

Watershed Protection Plan must include a watershed construction project, a watershed pollutant control program, and a watershed research and water quality monitori ng program. Under this legislation, the South Florida Water Management District (SFWMD), in collaboration with coordinating agencies, was directed to develop River Watershed Protection Plans for the Caloosahatchee and St. Lucie watersheds by January 1, 20 09.

A primary objective of the program to address the Caloosahatchee and St. Lucie Estuaries is to develop “pollutant load reductions based upon adopted total maximum daily loads established in accordance with s. 403.067” (Senate Bill 392, 2007). After t he TMDLs are completed, Basin Management Action Plans (BMAPs) will be developed. The TMDL for the St. Lucie estuary was proposed for final agency action on December 31, 2008. A notice of change to correct a minor typographical error in the rule will be p ublished in the Friday, January 23, 2009 issue of the Florida Administrative Weekly . As of January 14, 2009, a draft TMDL for tidal portions of the Caloosahatchee River and Estuary is near completion

, and it is anticipated that it will be completed, revie wed, and made publicly available by early February 2009.

In addition to the site

- specific efforts previously mentioned, FDEP is actively involved in GOMA.

It is working with the other Gulf states to develop broader

- based strategies for developing

nutrient criteria and control programs within the shared waters of the Gulf of Mexico. FDEP has assigned two staff members to directly participate in GOMA. Nutrient criteria

– related activities are being coordinated between these staff and FDEP’s Water Quality St andards P rogram. An example of these ongoing activities includes a comprehensive session on water quality sampling and quality assurance (QA) that was provided to GOMA staff by the Standards and Assessment Section during the summer of 2008.

FDEP recognize s that inland water criteria must protect downstream uses, and since estuarine condition is affected by the nutrient loads delivered from upstream, there will be effort made to synchronize these two criteria development efforts.



## 3.1 3 Microcystin Round Robi n

In an effort to initiate the development of a useful response threshold to HABs, FDEP has begun
a series of Q A “round robin” studies to evaluate the precision and accuracy of laboratory analytical results for microcystins. Because of the moderately la rge interlaboratory variability

associated with these analytical results, further work to achieve consistency between labs is needed to further develop reliable indicators of HABs

.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 45 

## 4

. Relation to State Use Classifications

The C WA requires that the surface waters of each state be classified according to designated

uses. Florida has five classes with associated designated uses, which are arranged in order of

the degree of protection required: Class I (potable water supplies); Class II (shellfish propagatio n or harvesting); Class III (recreation, propagation of fish and wildlife); Class IV (agricultural water supplies); and Class V (navigation, utility, and industrial use). Under the

current classification system, the majority of the state ’ s waterbod ies ( i. e.

, lakes, streams, estuaries, and wetlands) are Class III and are held to the same water quality criteria , with some differences between predominately fresh and marine waters



## 5

. Relation to Biogeographic Classification

FDEP initially used Level IV ecolog ical subregions, separately defined for streams (Griffith et al

., 1994) and lakes (Griffith et al

., 1997) in Florida’s biocriteria development program, as a starting point for regionalization efforts necessary to establish nutrient criteria. FDEP has anal yzed stream reference site macroinvertebrate community patterns in all nine ecological subregions north of Lake Okeechobee (Barbour et al.

, 1996). The data indicated the presence of the following four distinct bioregions, within which there were similar b iological community composition and structure ( Figure 4 ) : the panhandle ( R egions 65f, 65g, and 65h, and the majority of 75a ) , the northeast ( Re gion s 75e and 75f), the peninsula ( R egions 75b, 75c, and 75d, and a small part of 75a), and the Everglades ( R egi ons 76a, 76b, 76c, and 76d).

Similar patterns of relatively homogeneous groupings in the peninsula versus the panhandle have been observed in wetlands macrophyte, algae, and invertebrate data (Lane et al

. , 2003). Lake macrophyte (for percent invasive sp ecies) and invertebrate (based on ecoregion, pH, and color) indices also utilize a similar bioregion scheme, with the three peninsular ecoregions being collapsed into a single peninsular bioregion (Fore

, 2005 ; Gerrittsen et al

. , 2000). FDEP is currently e valuating the potential of using ecological subregions collapsed into biological regions as the basis for future nutrient criteria groupings, although the issue is still a matter of continued

discussion with the TAC (Weaver

, 2006 b , 2006 c ; Weaver and Fryden borg

, 2006).

Based on the observed biological community resemblance within a bioregion, it is logical that these biologically similar regions will have analogous ly comparable responses to nutrient

concentrations. If additional data indicate an alternate s patial classification scheme is more appropriate, the current system may be revised; however, current biological data suggest that bioregions are the most defensible approach to establish the appropriate protection of biota

.

The current bioregions were d erived based on macroinvertebrate assemblage patterns, which may not be entirely indicative of homogeneous response to nutrients. FDEP and its consultants are currently evaluating bioregions based on stream periphyton assemblages. If these

evaluations re veal significantly different biological regions

, the nutrient spatial classifications will be adjusted accordingly.

FDEP and the TAC are also evaluating scientifically defensible bases for the subregionalization

of known natural ly high

- phosphate areas in t he central peninsula and north

- central Florida (Weaver

, 2006c ) . Currently, in the peninsula bioregion pilot study, FDEP used an outlier analysis to exclude these naturally high

- phosphate areas. It intends to evaluate other methods

to explicitly subregion alize these areas.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 46 

## 6

. Data Sources

6.1 Inventory of Existing Data

Florida has invested significantly in the acquisition and storage of scientifically defensible water quality and biological data. The state water quality database currently houses over 19 million data records, including over 890,000 phosphorus, 1 million nitrogen, and 450,000 chlorophyll a

measurements. Additionally, FDEP has collected 3,867 SCI samples to assess stream health

, 53 4 vegetation samples to assess lake health , 7,265 periphyton samples, and 7

, 897 phytoplankton samples . These biological samples allow FDEP to make connections between water chemistry and aquatic health to assist with determining protective values in a complex

environment.

Under FDEP’s watershed approach, the iden tification of data sources and development of tools to facilitate data entry and upload to the S TO rage and R ET rieval ( STORET ) Database have become high priorities for the agency. Florida’s I WR (Chapter 62

- 303, F.A.C.) designates STORET (and its successor database) as the primary data source to be used by FDEP to assess water quality under the watershed approach. Efforts to upload new and additional data of known and defensible quality, under FDEP’s Quality Assurance Rule (Chapter 62

- 160, F.A.C.) are ongoi ng and supported by a dedicated STORET group within FDEP. This group provides support to other state agencies, local governments, and various organizations in the
transfer of data to Florida STORET.



## 6.2 FDEP’s Ambient Monitoring Program

In 1996, F DEP r edesigned its water resource monitoring programs to create an efficient, multi

resource, comprehensive monitoring network. While t he revised network

, called the Integrated Water Resource Monitoring (IWRM) Network, was designed to fulfill many different mo nitoring

needs , it includes two statewide monitoring programs (described below) that provide data that have proven invaluable in FDEP’s efforts to develop numeric nutrient criteria. It is anticipated

that addition al IWRM data will continue to be relied up on heavily for future nutrient evaluations.

The first IWRM program is a fixed

- site statewide T rend M onitoring network. The objective of the

Trend M onitoring program is to measure and estimate changes in the condition of water

resources over time. FDEP’s Watershed Monitoring Section samples 75 rivers and streams monthly for chemical and field analytes. In addition, benthic community and habitat assessments are conducted annually.

The second IWRM program, the Status Monitoring network, uses a stratified random sampling (probabilistic) design. The objective of the network is to broadly characterize the proportion of

state water resources that meet or do not meet water quality standards. This statistical design was selected because sampling all water reso urces throughout the state would be cost and resource prohibitive. The Watershed Monitoring S ection generates lists of representative surface and ground water sites, submits them to EPA for random selection, and samples 30 sites per resource, by basin. A s part of the design, the s ection sample s 6 different resources

, as follows: 4 surface water types ( rivers, strea ms, small lakes of 4 to less than 10 hectares

, and large lakes of more than 10 hectares), and 2 ground water aquifer types ( confined and

unconf ined ) . Samplers collect a standard suite of chemical, physical

, and biological parameters

to estimate the condition of the state ’s water resources. Currently, the Watershed Monitoring Section collects 180 samples per resource in the state

, or a total of 1

, 080 samples/year.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 47 Starting in 2009, the Watershed Monitoring Section will continue to collect Status Monitoring network samples from all 6 resource types, but the numbers collected and the sampling frequency will change. Sixty samples of each of the su rface water types will be collected, with a repeat visit resulting in a total of 120 samples/surface water resource/year. The repeat visits are scheduled at opposite seasons and rainfall patterns during the calendar year, thus capturing potential differen ces in water quality. However, the 2 ground water resources will be sampled once per year, resulting in 120 samples of each type. The fixed

- site

, statewide Trend

M onitoring network will remain the same.

FDEP’s watershed approach includes a strategic moni toring phase to gather new data within watersheds to supplement existing data. This monitoring is used to further characterize basin

conditions

, to investigate areas with identified or potential water quality problems

, to evaluate

the effectiveness of man agement actions

, and for TMDL development. These activities, addressed in strategic monitoring plans, are intended to identify data gaps at the watershed

level

, to prioritize areas of data collection by FDEP or other partners

, to establish a process for

d ata dissemination

, and to specify quality assurance/quality control ( QA/QC ) requirements.



## 6.3 Requirements for New Data Collection

Although FDEP has invested significant resources in its efforts to assess the ecological health

of the s tate’s waters, the process of developing numeric nutrient criteria has proven daunting. Most of the data described above were not originally collected for this purpose and thus have proven of limited value to derive protective response

– based criteria. One of the greatest

c hallenges is the fact that biological and water chemistry monitoring have been conducted on different temporal and spatial scales, making it difficult to appropriately pair nutrient and biological response data in a manner that can be used t o link biologic al impairment to nutrient

thresholds across a bioregion or ecoregion. As discussed previously, FDEP is currently conducting or initiating additional studies specifically aimed at making the necessary linkages

for both streams and lakes

.

FDEP is committed to pursu ing additional grants and other funding opportunities to support specific projects directed toward establishing numeric nutrient criteria, including the collection of

additional data. As the TAC identifies key parameters for criteria development, new data gaps may arise; therefore, it is not possible , at this time, to know how much data collection will be needed to propose ecoregional nutrient criteria.



## 7

. Coordination with Bordering States

Florida shares some waterbodies with Alabama

, Georgia

, the Miccosukee Tribe, and the
Seminole Tribe . Therefore, efforts will be made to coordinate with those states and tribes on any nutrient criteria Florida is considering on shared lakes and streams, prior to submittal to the
ERC for rule development. Additio nally, FDEP will meet with other Gulf of Mexico states to
discuss the adoption of nutrient criteria for Gulf estuaries.



## 8

. Prioritization of Waters and Schedule for Development and Adoption

FDEP initial ly prioritized waters for the development and adoption of regional numeric nutrient

criteria based on the availa bility of EPA guidance document s

— i.e., lake and river streamState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 48 guidance were avai lable first, followed by estuaries and coastal waters , and finally wetland guidance

. However

, the development of site

- specific numeric nutrient target s has been driven by TMDL development schedules , including a number of nutrient TMDLs for specific waterbodies, to be completed in accordance with the consent decree between EPA Region 4

and EarthJustice. Furthermore

, FDEP will continue to identify (and prioritize for TMDL development) other waterbodies identified as potentially impaired by nutrients under Chapter

62

- 303, F.A.C.

T he se site

- specific TMDL efforts are highly integrated with regional nutrient criteria developm ent
because information and experience gained in each effort has been and will continue to be used to refine the other. Methods originally developed by the TAC and FDEP to derive regional nutrient criteria have been used by FDEP to develop recommend ed TMD L thresholds for specific waterbodies. Conversely, site

- specific targets developed via the TMDL process will be evaluated for potential regional application or possible consideration as site

- specific nutrient

criteria for given waterbod ies , particularly f or estuaries and coastal waters.

FDEP has already made significant progress towards nutrient criteria development for streams and lakes, and anticipates continuing on a schedule consistent with EPA ’s expectation s for

substantial progress towards criteria adoption (Grubbs

, 2001 ). FDEP ’s c ommitment to this nutrient criteria development process is demonstrated by the assignment of seven staff and a

statistical consultant to work at least part

- time on this project ; FDEP ’s continued consultation

with its nutri ent criteria development TAC ; and FDEP staff participation in numerous regional

and national nutrient criteria

– related meetings, workshops, and conferences ( e.g ., Region 4 Regional Technical Assistance Group [ RTAG ] , 2006 All States Meeting , G OMA )

.

As FDE P ’s schedule follows the availability of EPA guidance documents, the state schedule is affected by the availability of those guidance documents and approaches

. C ontinued progress on this schedule is also contingent on continued funding through state and f ederal programs to

assist in completing the necessary research, develop ing appropriate assessment tools, and

verif ying the criteria.



## 8.1 Lakes and Streams (1 st 

## Priority)

Florida identified l akes and s treams as its first priority for the development and a doption of regional numeric nutrient criteria. FDEP has been meeting with the TAC and primarily discussing the development of nutrient criteria for these waters since January 2003. The TAC

has held 16 meetings addressing various topics related to lake, s tream, and canal nutrient

criteria. Summaries of these meetings and meeting materials are provided on FDEP ’s website ( http://www.dep.state.fl.us/water/wqssp/nutrients/tac_arc hive.htm )

. FDEP currently anticipate s that the TAC process for lakes and streams will be concluded by December 2009

, with numeric water quality criteria subsequently submitted to the ERC by 2011

.

FDEP currently plan s to develop benchmark distributional approach

– based criteria for lakes only as a backup

, because it believes it is currently close to developing response

- based criteria for lakes. However, FDEP may revisit the benchmark distributional approach for lakes if

response

- based approaches fail to identi f y significant relationships with nutrient enrichment.

The schedule below provides additional detail on Florida’s progress to date and anticipated

future activities

. It should be noted that the projected future milestones are based on the assumpti on that FDEP ’s current track and technical approach es are acceptable to EPA , and that there are no administrative challenges to adopti ng the criteria

.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 49 It should also be noted that, w hile the schedule for criteria development does not make a specific dist inction for south Florida streams/canals, criteria development for these systems may

be unique because there currently are very limited bioassessment methods applicable to

streams in Ecoregion XIII ( Figure 1 ). As part of developing the stream criteria, FD EP plans to evaluate the nutrient criteria developed for peninsular Florida streams to determine whether they are adequately protective of south Florida streams

.



## 8.2 Estuaries (2 nd 

## Priority)

FDEP selected estuaries as the second priority because of the s ite

- specific nature of nutrient response in estuaries and because there currently are very limited bioassessment tools

available for estuaries

. EPA ’s (2001) nutrient criteria guidance for e stuar ine and coastal marine

waters recognized th e site

- specific na ture of nutrient response in estuaries, not ing that

“ estuaries and coastal marine ecosystems tend to be relatively individualistic in their sensitivity and response to nutrient over enrichment.” The guidance further states that “the lack of physically sim ilar waterbodies may severely limit grouping (classifying) waterbodies as recommended for lakes, reservoirs, rivers, and streams where frequency distributions are used

to derive reference conditions.” FDEP concurs with these findings and anticipates that numeric

nutrient criteria for Florida’s estuaries and coastal waters will rely on both site

- specific efforts, including TMDL

- related efforts

, and the general approaches described below

.

EPA is assisting FDEP in the development of numeric nutrien t criteri a through the involvem ent of the EPA Office of Research and Development, Gulf Ecology Division, Gulf Breeze

La bora t ory. EPA/ GED plan s to focus on nutrient criteria development for estuaries over the

next 12 to 24 months. There is likely to be uncertainty surrounding the observation of a single, comprehensive, statistically significant relationship between nutrient concentrations ( or loads ) and observed biological responses for all of Florida’s estuaries due to their geological and ecological variability

. The s tate recognizes that a one

- size

- fits

- all approach to its estuaries may yield limited results . However, if a strong enough relationship can be generated in some Florida estuaries, and realistically applied to the remaining estuaries, the protection pr ovided would

serve as a solid foundation as more is learned about each estuary.



## 8

. 3 Wetlands (3 rd 

## Priority)

Florida leads the nation in the development of protective nutrient criteria for wetlands, having adopted a numeric phosphorus criterion for the Ev erglades in 2004

, well in advance of EPA ’s draft wetland guidance. In fact, this guidance includes an appendix summarizing much of the research used to establish the Everglades phosphorus criterion of 10 **μ** g/L. Furthermore, the

state leads the nation in i nnovative treatment and best management practice ( BMP ) technologies and research to achieve compliance with ultralow nutrient standards ( e.g

. , Burns

and McDonnell

, 2003 ; Piccone

, 2007).

FDEP does not plan to initiate the development of r egional wetland n utrient criteria until after the estuary nutrient criteria are into the rule development phase. EPA released draft wetland guidance for review in December 2006 ( EPA

, 2006) , and s pecifically solicited information, data,

and views on scientific issues perta ining to the information the agency used to develop th e draft

document. Under this request

, FDEP submitted review comments on the draft wetland guidance on February 15, 2007. EPA finalized its guidance in September 2007

. FDEP is currently r evaluat ing it s statewide wetland strategy with the expectation that Florida’s next planState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 50 update will include more specific strategies for wetland nutrient criteria development, including

time frames and milestones.

The lower priority assigned to wetlands is based on an acknowledgment that wetland s are biologically very different from other waterbody types

, that the state of the science on wetland nutrient dynamics is still evolving

, that biological and water quality monitoring efforts for

wetlands general ly lag behind th ose of other waterbody types

, and that with a few notable

ex ce ptions

, wetlands tend to have a higher nutrient assimilative capacity. The implementation

of nutrient threshold research or benchmark condition evaluations will take some time

, given the

curr en t state of wetland science.



## 9

. Florida’s Ongoing Investment in Nutrient Criteria Development

T able 5 lists the funding Florida has provided for nutrient criteria development during the past

several years, and includes studies planned for the next year.



## 1 0. Past, Current, and Future Schedule for Nutrient Criteria Development for Florida’s Waters

This section summarizes both previous efforts and planned activities for the development of

numeric nutrient criteria for Florida’s waters. Previous efforts were specifically included because it is important to recognize the previous investments (in time and money) that have laid the groundwork for the establishment of b iocriteria and numeric nutrient criteria. As evidenced throughout this document, FDEP strongly believes that scientifically defensible numeric nutrient criteria should be based on biological responses to nutrients. As such, it has invested significant resources in the development of biological assessment tools. This very complex process has requir ed extensive methods development, staff training, and Q A oversight to

ensure the defensibility of the resulting products. The e lements of this development and assessment process to date include habitat assessment for streams and lakes, benthic

invertebrat e indices for streams and lakes, a vegetation index for lakes, and a periphyton index

for streams.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 51 

### Table 5. Recent and p lanned f unding for n utrient c riteria d evelopment in

Florida

Project or Activity Cost to Date

S CI /Bio R econ Development $3,737,500

L VI Development $358,750

L CI Development $1,180,000

S PI Development $1,020,000

Biocriteria Meetings and Q A Activities $530,400

Stressor Identification Study $374,500

Nutrient Gradient Study $132,675

Stream Benchmark Site Determination $91,350

Longitudi nal Study $38,400

Springs Nitrate Studies $384,000

Staff Technical Analysis and Coordination Time $292,000

Statistical Consultants $175,000

Nutrient Criteria Meeting Travel $33,200

Everglades T P Criterion Development $11,250,000

Total Numeric Nutrien t Criteria Development Costs $19,597,775

FDEP also made major investments in the development of nutrient criteria for the Everglades, leading to the adoption of a p hosphorus criterion. Although work on other wetlands has begun,

additional validation a nd calibration of the wetland indices are needed prior to proceeding to nutrient criteria development for other wetlands . Because of their complexity and the confounding effects of salinity, FDEP currently ha s only limited bioassessment tools for

estuarie s and still need s to make significant progress in that area.

It should also be noted that this schedule and plan focus primarily on the scientific components of numeric nutrient criteria development. However, the successful adoption of numeric nutrient

cr iteria also depend s on the successful completion of the administrative rulemaking process, and it is very difficult to estimate the time frame for the rulemaking process, particularly given the potential for administrative challenges.

Past , current, and pl anned activities for the development of numeric nutrient criteria are as follows:

1992 To begin the phosphorus criterion development process in the Everglades , a research plan was developed to specifically determine the level of phosphorus
necessary to pr event an imbalance in Everglades flora and fauna. This plan, the Everglades Nutrient Threshold Research Plan (Lean et al., 1992), was intended to provide appropriate data in support of a numerical interpretation of the existing state of Florida narrative nutrient criterion.

June 1995 FDEP formed the Everglades Technical Advisory Committee (ETAC) to review

and comment to FDEP on Everglades r esearch and monitoring in support of the process of developing a numeric phosphorus criterion for the Everglades

. Sept . 1999

– Oct. 2001 FDEP staff publish ed and revise d three technical support documents in support of a numeric phosphorus criterion for the Everglades Protection Area (Payne etState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 52 al., 2000, 2001a, 2001b). These reports recommend ed a phosphorus criterion

of 10 **μ** g/L.

Dec

. 2001 Based on the results of FDEP ’s extensive analyses, the agency filed a notice of rulemaking and recommended a protective Everglades TP criterion of 10 **μ** g/L for approval by the ERC.

FDEP c onducted a statewide numeric nutrient criteria develo pment “kickoff” meeting in Tallahassee.

March 2002 FDEP c reated a nutrient criteria website (accessible to the public at http://www.dep.state.fl.us/water/wqssp/nutrients/index.htm ) to facilitate the dissemination of information about Florida’s nutrient criteria development process. Th e site includes agendas, minutes, and presentations from the

Nutrient Criteria TAC meetings, copies of reports from the studies sponsored by FDEP on n utrient

- related topics, links to federal nutrient websites, and other pertinent information.

FDEP e stablished an electronic mail listserver to distribute information directly to interested parties.

April 2002 FDEP r efine d the first draft of Florida’s Nume ric Nutrient Criteria Development

Plan.

FDEP i dentif ied potential Nutrient Criteria TAC members.

FDEP r eceived a draft report from Tetra Tech, Inc. detailing efforts to date on

the review of nutrient data and proposed potential nutrient criteria for Florida

lakes.

FDEP r eceived a draft report from the University of Florida presenting paleolimnological characterization of predisturbance water quality conditions in Florida lake regions (Griffith et al

. , 1997).

FDEP h ire d a designated staff person to coordinate FDEP ’s nutrient criteria development efforts.

May 2002 FDEP s ubmit t ed the Draft Numeric Nutrient Criteria Development Plan to EPA Region 4 for review.

An FDEP representative p articipate d in the Region 4 RTAG and present ed an overview of Flor ida’s Numeric Nutrient Criteria Plan for comment by RTAG

members.

FDEP s olicit ed the participation of identified potential Nutrient Criteria TAC

members.

June/July 2002 FDEP staff p articipate d in the National Nutrient Team and the national

stakeholders ’ meetings in Washington, DC.

Dec

. 2002 The University of Florida complete d a contract to conduct paleolimnological Cyanobacteria pigment studies to determine if past changes in the abundance of Cyanobacteria coincide with fossil diatom analysis in Florida lakes.

Jan

. 2003 FDEP c onvene d first meeting of the Nutrient Criteria TAC.

March

– July 2003 The nutrient criteria coordinator position became vacant; therefore, no TAC meetings were held.

July 2003 The ERC approved the 10 **μ** g/L TP criteri on for the Everglad es Protection Area during a July 8, 2003 hearing . Subsequent to the approval by ERC, both environmental and agricultural interest groups filed administrative challenges to the phosphorus criterion rule. Following discussions with FDEP concerning the appl ication of the rule, all parties except the Miccosukee Tribe of Indians and the Friends of the Everglades withdrew their challenges.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 53 FDEP contract ed a position to work with the TAC

, to plan and facilitate/coordinate TAC meetings.

Aug

. 2003 FDEP h eld a sec ond TAC meeting in Tallahassee; agenda items include d Florida water quality standards overview, existing narrative criteria, potential

nutrient criteria tools

, and nutrient criteria development approaches.

Oct

. 2003 The University of Florida paleolimnologi cal project was completed and the final report received.

T he t hird TAC meeting was held in Orlando on Florida lake nutrient criteria and data availability.

Nov

. 2003 FDEP representatives participate d in the EPA Region 4 RTAG meeting in

Atlanta.

Nov. 2003

– Jan. 2004 A n administrative hearing was held to resolve the remaining challenges to the Everglades phosphorus criterion rule

.

Dec

. 2003 FDEP s ubmit ted a revised FDEP Nutrient Criteria Development Plan to EPA

.

Jan. 2004 FDEP h eld the fourth TAC meeting and start ed holding TAC meetings approximately every one and a half months.

FDEP representatives p articipate d in the EPA Region 4 RTAG meeting

.

Feb

. 2004 A d esignated FDEP staff position t ook over TAC facilitation/ coordination

duties

.

The f ifth TAC meet ing was held in West Palm Beach. The m eeting focuse d exclusively on canal nutrient criteria development

. April 2004 The sixth TAC meeting was held in Talla ha ssee

.

The s eventh TAC meeting (two days) was held in Fort Myers

. May 2004 The e ighth TAC meeting was held in West Palm Beach

.

June 2004 The final order filed by the Administrative Law Judge on June 17, 2004

, upheld all parts of the proposed Everglades phosphorus criterion rule

, finding that the rule “is not an invalid exercise of delegated legislative authority” by FDEP

. July 2004 EPA and the state reach ed mutual agreement on a Numeric Nutrient Criteria Development Plan for Florida

. Aug

. 2004 The ninth TAC meeting (two days) was held in Tampa

.

Nov. 2004 T he t enth TAC meeting was held in Tallahassee

.

J an. 2005 EPA approve d all portions of the Everglades p hosphorus c riterion rule, except the use of the assessment methodology specified in Appendix B of the Settlement Agreement in the Federal Everglades lawsuit, Case No. 88

- 1886

- CIV

- Hoeveler, U.S., as modi fied by Omnibus Order entered in the case on April
27, 2001.

Feb

. 2005 The eleventh TAC meeting was held in Gainesville

.

March 2005 Florida initiate d the Dissolved Oxygen/Nutrient Study, an intensive one

- year DO and nutrient study

. Nutrient and biologic al data were collected in streams, canals, and lakes across the entire state

. These data, in addition to other

ambient data available i n STORET

, will be used to establish numeric nutrient

criteria

. Additionally, data will be used to help establish new bi oassessment methods ( phytoplankton and periphyton indices )

. April 2005 A revised Everglades p hosphorus c riterion rule was presented to the ERC and

receive d unanimous approval on April 7, 2005.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 54 June 2005 The Everglades p hosphorus c riterion rule was resubmit ted to EPA for approval

. July 2005 The Everglades p hosphorus c riterion receive d final approval from EPA

. Aug

. 2005 T he t w elfth TAC meeting (two day s ) was held in West Palm Beach

.
Oct

. 2005 FDEP representatives participate d in the EPA Region 4 RTAG meeting in

Atlant a and p r esent ed an overview of the status of Florida’s numeric nutrient criteria development

.

Feb

. 2006 FDEP representatives participate d in EPA ’s A ll S tates N umeric N utrient C riteria

M eeting in Dallas

.

T he t hirteenth TAC meeting was held at Wakulla Springs State Park , Wakulla.

May 2006 The f ourteenth TAC meeting was held in Gainesville.

DO and nutrient study data collection were completed.

Oct

. 2006 The fifteenth TAC meeting was held in Ponte Vedra Beach

.

Dec

. 2006 The s ixteenth TAC mee ting was held in Tallahassee.

Jan. 2007 FDEP establishe d and SFWMD beg an monitoring an ambient monitoring network in the Everglades Protection Area designed to a ss ess the achievement of the Everglades phosphorus criterion rule.

FDEP representatives partic ipate d in the G OMA Nutrient Criteria Conference in

Gulf Breeze.

Feb

. 2007 FDEP submitted a revised Numeric Nutrient Criteria Development Plan to EPA

.

FDEP s ubmitted review comments on EPA ’s Draft Nutrient Criteria Technical

Guidance Manual for Wetlands ( E PA 823

- F

- 05

- 015

– December 2006).

March 2007 FDEP representatives participated in the EPA Region 4 RTAG meeting in Decatur, GA.

May 2007 FDEP submitted to EPA Region 4 a pilot study application of its benchmark

distributional approach as part of FDEP ’s com ments on EPA ’s Proposed Total Maximum Daily Load (TMDL) f or Biochemical Oxygen Demand, Dissolved Oxygen, Nutrients

, and Unionized Ammonia In the Lake Okeechobee

Tributaries

. Aug

. 2007 All macroinvertebrate, periphyton, and phytoplankton data from the inten sive

one

- year DO and nutrient study were marked complete and entered into Florida’s biological database.

Feb

. 2008 The seventeenth TAC meeting was held in Tallahassee. FDEP received positive feedback from EPA on the application of the benchmark distributi onal approach as utilized in FDEP’s pilot study for peninsula bioregion streams.

March 2008 The Nutrient Gradient Study sampling was initi ated.

June 2008 FDEP h eld the e stuaries and coastal waters numeric nutrient criteria kickoff meeting with the existing TAC and other experts , and provide d training to GOMA staff on water quality sampling and QA

. Aug

. 2008 FDEP analyze d algal response to nitrate concentrations in spring systems and

propose d a criterion of 0. 35 mg/L during the triennial review process.

Sum mer 2008 FDEP c reated a strategy for developing estuar ine criteria and wrote scope of

work for EPA assistance.

June 2008

– Dec. 2009 FDEP c ontinue s data synthesis and analysis ( e.g ., biological indices, regionalization analyses) for lakes, streams, and canal s, and meet s with the

TAC as needed.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 55 FDEP c ontinue s additional data collection as needed

.

Summer /Fall 2008 FDEP gather ed LVI readings from targeted lakes to be used to explore relationships with nutrient concentrations and c onduct ed QA testing of all LVI

teams to ensure data usability

. Sept

. 2008 FDEP representatives participate d in the planned EPA Region 4 RTAG meeting.

Nov

. 2008 A contract to develop the stressor identification conceptual model was initiated

and the contractor began reviewing data. An i ntensive kick

- off meeting was conducted in January 2009.

Dec

. 2008 FDEP c ompleted fieldwork for the validation of peninsula, panhandle, and northeast bioregion benchmark streams.

Dec

. 2008 FDEP staff me t with EPA Headquarters and EPA G ED staff to discuss the project to develop numeric nutrient criteria for estuaries.

Jan. 200 9 FDEP to collect final data and information related to the Nutrient Gradient Study

. Approximately 95% of these data were collected by December 2008. FDEP completed sampling for Long itudinal Study

Feb 2009 FDEP convened (with EPA support and participation) a panel of national
experts to assist and advise FDEP in the calibration of a Stream Periphyton Index (SPI)

M arch

– April 200 9 FDEP plans to g enerate draft benchmark distributional ap proach

– derived stream nitrogen and phosphorus thresholds as potential backup criteria

.

March

– April 2009 FDEP to a nalyze data and information collected during the N utrient G radient

S tudy and analyze nutrient statistics related to the L VI.

May 2009 FDEP to generate draft response

– based nutrient criteria for streams

, lakes

, and estuaries if the statistical rigor of the results is sufficient (see Table 3 for specific causal and response variables). . If results are not sufficient, a six

- to eight

- month delay may occur to collect and analyze additional data.

July 2009 FDEP plans to gather data appropriate for nutrient criteria development in Ecoregion XIII streams/ canals

.

Dec

. 2009 Conclude TAC process for lakes and streams , and potentially estuaries (if GED efforts are successful)

. Anticipated products include the recommended

numeric nutrient criteria for Florida lakes

, streams

, and Ecoregion XIII
streams/ canal s, and estuarie s

, and draft rule language to be incorporated into state water quality standards (se e Table 3 for specific causal and response variables).

.

Jan

. 2010

– Dec. 201 0 DEP conducts formal r ulemaking to incorporate nutrient criteria into Florida’s water quality standards (Chapters 62

- 302 and 62

- 303 , F.A.C. )

. FDEP works to

r efine d raft rule text

, allowing time for draft rule review and public workshops on

the proposed rule before the nutrient criteria rule language is submitted to the

ERC

. It is anticipated that the rulemaking process will take approximately 12

months

.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 56 

## References Consulted or C ited

Barbour, M., J. Gerritsen, and J. White. 1996. Development of the Stream Condition Index (SCI) for Florida. Owings Mills, MD : Tetra Tech, Inc

. Brown, M.T.

, and M.B. Vivas. 2005. Landscape Development Intensity Index

. Environmental Monitoring an d Assessment 101: 289

– 309

Brown, M.T.

, and K.C. Reiss. 2006. Proposed breakpoint of LDI < 2.0 for determining minimally affected reference conditions for water bodies. Gainesville, FL: Center for Environmental Policy, Department of Environmental Enginee ring Sciences, University of

Florida. Technical r eport Submitted to the Florida Department of Environmental Protection.

Burns and McDonnell. October 2003. Everglades Protection Area tributary basins long

- term plan for achieving water quality goals

. Repo rt prepared for the South Florida Water Management District, West Palm Beach, FL.

Davies, S.P.

, and S.K. Jackson. 2006. The biological condition gradient: a descriptive model for interpreting change in aquatic ecosystems. Ecological Applications 16(4):1 251

- 1266.

F lorida Department of Environmental Protection . 1998. 303(d) list of impaired waters

. Tallahassee, FL: Florida Department of Environmental Protection.

——— . 2008. Florida Department of Environmental Protection standard operating procedures

, Tallahassee, FL

.
Fore. L.S. 2004. Development and testing of biomonitoring tools for macroinvertebrates in

Florida streams

. Final r eport to the Florida Department of Environmental Protection.

———

. 2005. Assessing the biological condition of Florida lakes : Development of the Lake Vegetation Index (LVI). Final r eport to the Florida Department of Environmental Protection.

Fore, L.S., R. Frydenborg, D. Miller, T. Frick, D. Whiting, J. Espy, and L. Wolfe. 2007a. Development and testing of biomonito ring tools for macroinvertebrates in Florida streams (Stream Condition Index and BioRecon )

. Final r eport to the Florida Department of

Environmental Protection.

Fore, L.S. , R. Frydenborg, N. Wellendorf, J. Espy, T. Frick, D. Whiting, J. Jackson

, and J.

Pa tronis. 2007b. Assessing the biological condition of Florida lakes : Development of the Lake Vegetation Index (LVI ). Final r eport to the Florida Department of Environmental

Protection.

Gerritsen, J., B. Jessup, E

. W. Leppo, and J

. White. 2000. Developme nt of Lake Condition Indices (LCI) for Florida. Final r eport to the Florida Department of Environmental

Protection.

Griffith, G.E., D.E. Canfield, Jr., C.A. Horsburgh, and J.M. Omernik. 1997. Lake regions of

Florida. Environmental Research Laboratory, Corvallis, OR: U .S. Environmental Protection Agency.

Griffith, G.E., J.M. Omernik, C.M. Rohm, and S.M. Pierson. 1994. Florida regionalization project

. Corvallis, OR: Environmental Research Laboratory, U .S. Environmental Protection Agency.

Grubbs, G. November 14, 2001. Development and adoption of nutrient criteria into water quality standards

. Memorandum to Water Directors, Regions I

– X ; Directors, State Water Programs ; Directors, Great Water Body Programs ; Directors, Authorized Tribal WaterState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 57 Quality Standards Programs ; State and Interstate Water Pollution Control Administrator s

. Washington, DC: WQSP

- 01

- 01. Washington, DC: U.S. Environmental Protection Agency, Office of Science and Technology.

Hand, J., J. Col, D. Tterlikkis, J. Jackson, R. Odo m, L. Lord, and L. Clemens. 2000. Florida water quality assessment 305(b) report

. Tallahassee, FL: Florida Department of

Environmental Protection.

Hendrickson, J.C., E.F. Lowe, D. Dobberfuhl and D. Campbell. 2003. Accelerated eutrophication in the Lowe r St. Johns River Estuary and recommendation of targets for the

achievement of water quality goals to fulfill TMDL and PLRG objectives

. Palatka, FL: Water Resources Department Technical Memorandum, St. Johns River Water Management

District.

Jacobs, T.C.

, and J. W. Gilliam. 1985. Riparian losses of nitrate from agricultural drainage

waters. Journal of Environmental Quality 14:472

- 478.

Jordan, T.E., D.L. Correll, and D.E. Weller. 1993. Nutrient interception by a riparian forest receiving inputs from adj acent cropland. Journal of Environmental Quality 22:467

- 473.

Lane, C.R., M.T. Brown, M. Murr a y

- Hudson, and M. B. Vivas. 2003. Wetland Condition Index (WCI): Biological indicators of wetland condition for isolated depressional herbaceous

wetlands in Flo rida. Gainesville, FL: Howard T. Odum Center for Wetlands, University of

Florida

. Report to the Florida Department of Environmental Protection.

Lean, D., K. Reckhow. W. Walker, and R. Wetzel. 1992. Everglades nutrient threshold plan

. Research and Mo nitoring Subcommittees of the Everglades Technical Oversight

Committee.

Lowrance, R. 1997. Water q uality f unctions of r iparian f orest b uffers in Chesapeake Bay

w atersheds. Environmental Management 21:687

– 712.

———

. 1992. Groundwater nitrate and denitrif ication in a coastal plain riparian soil. Journal of Environmental Quality 21:401

- 405.

Niu, X. 2004. Change point analysis of the chlorophyll

- a and LDI data from the IWRM Status Network Cycle 1 l akes s tudy

. Tallahassee, FL: Department of Statistics, F lorida State University. Technical r eport s ubmitted to the Florida Departme nt of Environmental Protection, Tallahassee, FL.

Niu, X, and X. Gau. 2007 . Change point analysis of Suwannee River algal data. Technical report prepared for the Florida Departme nt of Environmental Protection

. Technical r eport

s ubmitted to the Florida Departme nt of Environmental Protection, Tallahassee, FL.

Niu, X., P. Lin., and D. Meeter

. 2000. Detecting change points in the species composition and water quality data of WCA2A. Tallahassee, FL: Department of Statistics, Florida State University. Technical r eport s ubmitted to the Florida Departm ent of Environmental Protection, Tallahassee, FL.

Payne, G., K. Weaver, T. Bennett

, and F. Nearhoof. 2000. Everglades phosphorus cri terion development support document , Part 1: Water Conservation Area 2. Tallahassee, FL: Everglades Technical Support Section, Division of Water Resource Management.

———

. 2001a. Everglades phosphorus criterion development support document , Part 2: Wat er Conservation Area 1. Tallahassee, FL: Everglades Technical Support Section, Division of Water Resource Management.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 58 ———

. 2001b. Everglades phosphorus criterion development support document , Part 3: Water Conservation Area 3 and Everglades National P ark. Tallahassee, FL: Everglades Technical Support Section, Division of Water Resource Management.

Peterjohn, W.T., and D.L. Corell. 198 5 . Nutrient dynamics in an agricultural watershed: Observations on the role of a riparian forest. Ecology 65:1466

- 147 5.

Piccone, T. 2007. Implementation of the l ong

- t erm p lan for a chieving w ater q uality g oals in the Everglades Protection Area. G. Redfield, ed. In: 2007 South Florida e nvir o nmental r eport (West Palm Beach, FL: South Florida Water Management District )

. Pinowska, A., R. J. Stevenson, J. O. Sickman, A. Albertin, and M. Anderson. 2007. Integrated interpretation of survey for determining nutrient thresholds for macroalgae in Florida Springs: Macroalgal relationships to water, sediment and macroalgae nutrie nts, diatom

indicators and land use

. Technical r eport s ubmitted to the Florida Departme nt of Environmental Protection, Tallahassee, FL.

Stevenson, R.J., A. Pinowska, A. Albertin, and J.O. Sickman

. October 31, 2007. Ecological

condition of algae and nutr ients in Florida springs: The s ynthesis r eport. Final r eport to the Florida Department of Environmental Protection. East Lansing, MI: Department of Zoology, Michigan State University.

Stoddard, J.L., D.P. Larsen, C.P. Hawkins, R.K. Johnson and R.H. Nor ris. 2006

. Setting expectations for the ecological condition of streams: T he concept of reference condition. Ecological Applications 16(4):1267

- 1276

.
U .S. Environmental Protection Agency. 1991. The watershed protection approach : An

overview

. EPA 503/ 9

- 92

- 001. Washington, DC: Office of Water.

———

. 1995. Watershed protection : A statewide approach

. EPA 841

- R

- 95

- 004. Washington,
DC: Office of Water.

———

. 1998. National strategy for the development of regional nutrient criteria

. EPA 822

- R

98

- 002. Washington, DC: Office of Water.

———

. 2000a. Ambient water quality criteria recommendations

, i nformation supporting the development of state and tribal nutrient criteria : Lakes and reservoirs in Nutrient Ecoregion

IX. EPA 822

- B

- 00

- 011. Washington, DC: Office of Water.

———

. 2000b. Ambient water quality criteria recommendations

, information supporting the development of state and tribal nutrient criteria : Lakes and reservoirs in Nutrient Ecoregion

XII. EPA 822

- B

- 00

- 013. Washington, DC: Office of Water.

———

. 2000c. Ambient water q uality criteria recommendations

, information supporting the development of state and tribal nutrient criteria : Lakes and reservoirs in Nutrient Ecoregion

XIII. EPA 822

- B

- 00

- 014. Washington, DC: Office of Water.

— ——

. 2000d. Ambient w ater q uality c riteria r ecommendations

, i nformation s upporting the

d

evelopment of s tate and t ribal n utrient c riteria : Rivers and s treams in Nutrient Ecoregion

IX. EPA 822

- B

- 00

- 019. Washington, DC: Office of Water.

______ . 2000 e

. Nutrient criteria technical guidance manual : Rivers and streams. EPA 822

- B

00

- 002. Washington, DC: U .S. Environmental Protection Agency

.

______ . 2000 f

. Nutrient criteria technical guidance manual

– Lakes and reservoirs. EPA 822

- B

- 00

- 001. Washingto n, DC: U .S. Environmental Protection Agency.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 59 ———

. 2000 g

. Ambient water quality criteria recommendations

, information supporting the development of state and tribal nutrient criteria : Rivers and streams in Nutrient Ecoregion

XII. EPA 822

- B

- 00

- 021. Wa shington, DC: Office of Water.

———

. 2001. Nutrient criteria technical guidance manual : Estuarine and coastal marine

waters

. EPA

- 822

- B

- 01

- 003. Washington, DC: Office of Water.

———

. 2006. Draft nutrient criteria technical guidance manual : Wetland s. EPA

- 823

- B

- 05

- 003. Washington, DC: Office of Water.

Valiela , I.

, and M.L. Cole

. 2002. Comparative e vidence that s alt m arshes and m angroves m ay

p rotect s eagrass m eado w s from l and

- derived n itrogen l oads . Ecosystems 5:92

- 102.

Weaver, K. 2006 a

. Nutri ent criteria development update

. Presentation to the Florida Nutrient Criteria Development TAC, Feb ruary 22, 2006 m eeting

, Wakulla, FL. htt p://dep.state.fl.us/ water/wqssp/nutrients/docs/TAC/tac13_NutrientCriteriaDevelopmentUpdate.pdf

.

———

. 2006 b

. Nutrient criteria development update

. Presentation to the Florida Nutrient Criteria Development TAC, Feb ruary 22, 2006 m eeting

, Wakulla, FL. http://dep.state.fl.us/ water/wqssp/nutrients/docs/TAC/tac13_NutrientCriteriaDevelopmentUpdate.pdf

.

———

. 2006 c

. Derivation of numeric nutri ent criteria

. Presentation to the Florida Nutrient Criteria Development TAC, Dec ember 6, 2006 m eeting

, Tallahassee, FL. http://www.dep .state.fl.us/water/wqssp/nutrients/docs/TAC/tac16_NumericNutrientCriteriaDerivation.pdf

Weaver, K.

, and R. Frydenborg. 2006. Evolving approach for nutrient criteria development

. Presentation to the Florida Nutrient Criteria Development TAC, May 22, 2006 m eeting

. Gainesville, FL. .

http://www.dep.state.fl.us/water/wqssp/nutrients/docs/TAC/tac14_Evolving ApproachNutrientCriteria.pdf



### .State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 60State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 61 

## APPENDICES

A ppendix A: FDEP’s Review of EPA’s Recommended Nutrient Criteria

fo r Streams and Lakes

Prepared by the Florida Department of Environmental Protection, Bureau of Assessment and Restoration Support

Background

EPA’s Nutrient Criteria Technical Guidance Manual : Rivers and Streams ( Buck et al., 2000 ) described three general a pproaches for the development of numeric nutrient criteria for streams.

This appendix evaluates EPA’s third and least preferred approach, which involves establishing criteria using a lower distribution ( e.g

. , 5 th to 25 th percentile) of a pool of sites of unknown ecological quality in a designated ecoregion. It is FDEP’s position that this approach is not scientifically defensible, since there is no connection between the resulting thresholds and any environmental measure. A general population of data con tains an unknown mix of reference and nonreference sites with varying levels of impairment ( i.e., unknown ecological quality), allowing no predetermined relationship between the nutrient concentrations in this “unknown” population and any valued ecological attribute. Since there is no predestined relationship

between the 25 th percentile nutrient concentration of a general population and any biological response variable, nothing can be predicted concerning the level of protection afforded by a

criterion der ived using this approach.

EPA’s approach uses designated ecoregions ( Figure A

- 1 ). Florida’s ecoregions are IX, XII, and XIII. These ecoregions cover a large area, and waterbodies within each of these areas can experience vastly different environmental circumstances. Note that E coregion IX starts in Pennsylvania, comes down to Florida, heads north to Illinois, heads west to Nebraska, and ends

in Texas and Louisiana. EPA’s recommended nutrient criteria were derived based on data collected throughout thi s vast and heterogeneous region ( Figure A

- 2 ) and therefore cannot be expected to accurately reflect conditions in any particular state, including Florida.

The 25 th percentile concentration of the general population is purely dependent on the number

of si tes and their level of enrichment. This fact is acknowledged in EPA guidance (EPA

, 2000 a, 2000b, 2000c, 2000d, 2000e ). If the general population of data were primarily composed of minimally disturbed “reference” sites, a 25 th percentile criterion would r esult in these healthy sites being out of compliance

. Even worse, if nutrients were actually reduced below those needed for the proper functioning of these reference systems, adverse harm would occur. On the other hand, if the general population were pri marily composed of highly nutrient

- enriched sites, a criterion derived in this way might be under protective. It would be purely coincidence

that a criterion de veloped in this manner would be appropriate.

Therefore, any criterion derived based on the 25 t h percentile of data collected at a pool of random sites with unknown ecological quality is scientifically indefensible and unlikely to be upheld if challenged

, due to the fundamental technical flaws associated with this approach. However, EPA has taken t his method and recommended criteria for streams ( Table A

- 1 ) and lakes/impoundments ( Table A

- 2 ).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 62 

### Figure A

- 1. Aggregations of Level III e coregions for n ational n utrient s trategyState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 63 

### Figure A

- 2. Location of sampling stations used by EPA to derive Ecoregion IX

recommended nutrient criteria for rivers and streams and lakes

Table A

- 1. EPA r ecommendations for s treams u sing the l ower 25 th 

### p ercentile

a pproach of a d ataset of u nknown s ite q uality

Region IX

- Southeastern

Temperate

Forested Plains

and Hills Region XII

- Southern

Coastal Plain Region XIII

- Southern Florida

Coastal Plain ++

T P ( **μ** g/L) 36.56 40.00 N/A **

T N (mg/L) 0.69 0.9 N/A **

Chlorophyll a ( **μ** g/L) 0.93 0.40 N/A **

Periphyton Chlorophyll a (mg/m 3 ) 20.35 N/A * N/A **

Turbidity (NTU) 5.70 1.90 N/A **

N/A

– Not available

. * Periphyton chlorophyll a (mg/m 3 ) criteria recommendati ons were not included in the EPA publication addressing ambient water quality criteria recommendations for rivers and streams in Region XII.

** EPA has not issued ambient water quality criteria recommendations for rivers and streams in Region XIII. Rivers and Stream LakesState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 64 

### Table A

- 2. EPA recommendations for lakes/impoundments using the lower 25 th


### percentile approach of a dataset of unknown site quality

Region IX

- Southeaste rn

Temperate

Forested

Plains

and Hills Region XII

- Southern

Coastal Plain Region XIII

- Southern

Florida

Coastal Plain

T P ( **μ** g/L) 20.00 10.0 17.5

T N (mg/L) 0.36 0.52 1.27

Chlorophyll a ( **μ** g/L) 4.93 2.60 12.35

Secchi depth (m) 1.53 2.10 0.79

EPA notes in its national nutrient guidance documents that sampling protocols and analytical methods must demonstrate comparable data in order to compare data collected under different sampling programs or by different agencies, but EPA’s contractor did not perform such a review when assembling the national nutrient database. The review focused on the following:

(1) S ample location verifi cation;

(2) T he deletion of duplicate samples;

(3) T he deletion of samples downstream of effluent discharge points;

(4) T he verification of station identification numbers , HUC codes, county, and ecoregions; and

(5) T he verification of laboratory and sampling methods, where this information was available or in some cases when data generators responded to inquiries.

Several of the datasets (Legacy S TORET

, National Water Quality Assessment [ NAWQA ] , and National Stream Quality Accounting Network [ NASQAN ] ) received mini mal review by the contractor on the assumption that the review had previously been conducted by a previous

contractor

, or on the assumption that the source agency, the USGS, had reviewed the data for
QA/QC.

In short, the database lacks sufficient supportin g information to indicate that acceptable measurement procedures were used and that the results are reliable. This is inconsistent with the manner in which both aquatic criteria and human health criteria are established. EPA has very specific guidelines regarding the documentation of test controls, endpoints, and data quality for both criteria types ( Stephen et al., 1985; EPA

, 2000 a, 2000b, 2000c, 2000d, 2000e ). Equivalent scrutiny was not applied to the ecoregional numeric nutrient criteria

recommendati ons.

EPA’s handling of the national nutrient database also included a highly questionable data manipulation where values reported as less than the analytical detection limit were replaced with a value of zero. It is improbable if not impossible that the actual nutrient concentrations in the environment were zero. Additionally, values reported below the method quantitation limits were replaced with one

- half the reported value. These decisions very likely caused EPA’s

recommended criteria to be biased lo w.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 65 The method by which below detection and quantitation limit values are handled will bias low 25 th
percentiles and medians, when 25 and 50 % , respectively, of the values are below these limits. However, it is impossible to determine the actual degree to w hich EPA’s manipulations a ffected

the final recommendations because ( 1) they do not document the percentage of altered values

, and ( 2) the detection and quantitation limits used by the various data generators are not

documented.

Method detection and quan titation vary among data generators depending on analytical procedures, which change over time, and organizational policies. However, the recommendations and data summaries can be compared with typical detection and quantitation

limits used in Florida. F or example, typical Florida chlorophyll a detection and quantitation limits

are at or above 1 and 4 **μ** g/L, respectively. The seasonal 25 th percentile values used by EPA to

derive the stream recommendations are all below the 1 **μ** g/L detection limit, with one exception ( Tables A

- 3 and A

- 4 ). Furthermore, the seasonal 25 th percentiles and median values are a ll between the detection and quantitation limits. This strongly suggests that EPA’s data manipulations artificially biased its criteria recommendations. The recommendations reflect data manipulation artifacts rather than realistic or protective threshold s.



### Table A

- 3. Summary of seasonal values chlorophyll **a** concentrations used by EPA to derive the recommended Ecoregion IX r ivers and s treams chlorophyll **a** criteria

The criterion was calculated as the median of seasonal 25 th percentiles (P25).

S eason N M e an M inimum M aximum P5 P25 M edian P75

Fall 187 6.03 .000 78.60 0.25 0.9 2.85 7.50

Spring 206 6.54 .000 98.52 0.00 0.97 3.38 7.95

Summer 235 7.44 .000 79.20 0.00 1.03 3.48 9.00

Winter 178 3.13 .000 34.80 0.00 0.25 1.65 3.48



### Table A

- 4. Summary of seaso nal values chlorophyll **a** concentrations used by

EPA to derive the recommended Ecoregion XII r ivers and s treams chlorophyll **a** criteria

The criterion was calculated as the median of seasonal 25 th percentiles (P25).

Season N Mean Minimum Maximum P5 P25 Medi an P75

Fall 146 6.40 0.00 87.94 0.00 0.38 1.07 5.25

Spring 171 7.86 0.00 100.25 0.00 0.39 1.71 8.04

Summer 171 8.93 0.00 62.40 0.00 0.53 3.21 11.6

Winter 159 4.98 0.00 96.20 0.00 0.41 1.38 5.85

While these recommendations appear on the surface to re present water quality criteria that can be set for waterbodies, they are both incomplete and illogical. They are incomplete in that they only represent the magnitude of a criterion and do not provide duration and frequency. Duration is the averaging peri od that a criterion represents in order to be protective ( i.e., monthly average, annual average, instantaneous maximum, etc.). Frequency is the number of times the magnitude/duration expression can be violated and still protect the designated use ( i.e., n oState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 66 more than one exceedance per year, less than 10% exceedance over 5 years, etc.). Rarely does a single exceedance of a naturally occurring parameter impair the designated use.

While these values are incomplete, assuming they were established as an annu al average not

to be exceeded for the purposes of comparison with actual environmental data proves useful in trying to determine the logic of applying them to Florida waterbodies. Furthermore, the criteria recommendations are illogical from the perspectiv e of protecting designated uses. As previously stated, there is no predestined relationship between the 25 th percentile nutrient concentration of a general population and any valued ecological attribute linked to the designated uses. There is nothing tha t can be predicted concerning the level of protection afforded by a criterion derived using this approach.



### Application of EPA Criteria Recommendations

STREAMS

This section tests the application of the criteria to determine if they meet the CWA test in

Sect ion 303(b)(2)(A), “Such standards shall be such as to protect the public health or welfare, enhance the quality of water and serve the purposes of this Act.” The purposes of the CWA are defined in Section 101(a). The expectation of water quality standar ds to provide protection to waterbodies is further defined in federal regulation at 40 CFR Part 131.6 and Subpart B.

FDEP has identified a number of unimpacted reference streams in the central peninsula of the

s tate, called the peninsula bioregion ( Figure A

- 3 ). These streams represent conditions with minimal to no additional nutrient contribution from natural conditions. Therefore, one can conclude that the aquatic life in these waterbodies fully support the designated uses and are adapted to long

- standin g natural nutrient conditions. Figure A

- 4 shows the distribution of nitrogen, phosphorus, chlorophyll a , and turbidity concentrations associated with these

reference streams and the associated EPA criteria recommendation values.

The implementation of the criteria that EPA has recommended would result in the identification of many natural streams as impaired, and with a strict application of the CWA, would result in TMDLs requiring reductions in nutrient availability to the aquatic life dependent on the str eam for habitat. This reduction in nutrient availability is no different than reducing the food supply for the organisms, and will alter the biological integrity of the waterbody and limit the aquatic life contained in the waterbody. This is inconsistent with the goals of the CWA and federal regulations. Furthermore, the application of EPA’s recommendations would require the state to regulate and remediate nutrients below natural conditions in many streams throughout the state. This is illogical and wou ld result in a waste of public and private resources that could otherwise be invested to address real societal problems, including valid nutrient impairments.

An additional complication is that monitoring the biological integrity of streams is an evolving science. EPA has recommended the use of chlorophyll a and turbidity (water clarity) as indicator tools for measuring biological response in streams. While chlorophyll a and turbidity are a way to measure algal mass buildup in waters, they are not the bes t tool for flowing waterbodies, where the excessive growth of algae due to elevated nutrients is often in the form of algae growth attached to physical objects in the stream (streambed, rocks, logs, etc.), not suspended and floating in the water column. E PA’s chlorophyll a criteria recommendation is for suspended growth (floating algae). A better measure that is evolving involves an analysis of the attached plant community, known as periphyton. Figures A

- 5 and A

- 6 show the relationship

between excess nut rients and periphyton growth in the Suwannee River in Florida (one waterbody in Florida with extensive periphyton data).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 67 

### Figure A

- 3

. Stream bioregions of FloridaState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 68 

### Figure A

- 4. Cumulative frequency distributions of (A) tota l phosphorus, (B) total nitrogen, (C) chlorophyll **a** , and (D) turbidity in confirmed peninsula bioregion reference streams

The vertical blue dash

- dotted line indicates the EPA

- recommended 25 th percentile criterion for Ecoregion XII. The

intersection betwe en the curve and vertical lines demonstrates the percentage of biologically healthy streams (e.g., 80% for TP) that would be falsely identified as impaired if the EPA recommendations were adopted.

0 10 20 30 40 50 60 70 80 90 100

0 0.05 0.1 0.15 0.2 0.25

Total Phosphorus (mg/L)Percentile

Peninsula Bioregion Reference

Region XII 25th Percentile A

.

0 10 20 30 40 50 60 70 80 90 100

0 0.5 1 1.5 2 2.5 3

Total Nitrogen (mg/L)Percentile B

.

0 10 20 30 40 50 60 70 80 90 100

0 2 4 6 8 10

Turbidity (NTU)Percentile D

.

0 10 20 30 40 50 60 70 80 90 100

0 0.5 1 1.5 2

Chlorophyll (μg/L)Percentile C

.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 69 

### Figure A

- 5. Adverse biomass changes in Suwannee River periphyton related to anthropogenic nitrate

- nitrate levels

Phytoplankton chlorophyll is typically very low.



### Figure A

- 6. Increases in **Vaucheria** sp. (nuisance algae) in Florida spring runs related to anthropogenic nitrate

- nitra te levels (graph lists TN as axis, but this was predominantly nitrate

- nitrate)

Phytoplankton chlorophyll in springs is typically very low. Mean NOx (Mg/L)AFDW (g/Square-Meter)

0.0 0.2 0.4 0.6 0.80246

0.1 1 6 0 10 20 30 40 50 60 70 80 90 100



## Total N (mg/L)Vaucheria% coverState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 70 LAKES

FDEP has made very significant progress in the development of an LVI specifically designed to

assess the he alth of a quatic biological communities in lakes. While FDEP intends to evaluate

dose

- effect relationships between the LVI and nutrients, the LVI may also be used to identify biologically healthy, reference lakes. Lakes with an LVI score of 37 or greater support healthy biological communities that fully support the designated uses and are adapted to long

- standing

natural nutrient conditions. Figure A

- 7 shows the distribution of nitrogen, phosphorus, and chlorophyll a concentrations associated with these r eference lakes and the associated EPA

criteria recommendation values.



### Figure A

- 7

. Cumulative frequency distributions of ( A ) total phosphorus, ( B ) total nitrogen, and ( C ) chlorophyll **a** in Florida lakes with healthy aquatic plant communiti es (LVI ≥ 37)

The vertical green and blue dashed line s indicate the EPA

- recommended 25 th percentile criterion for E coregions XI and XII, respectively. The intersection between the curve and vertical lines demonstrates the percentage of biologically healt hy lakes that would be falsely identified as impaired if the EPA recommendations were adopted.

0 10 20 30 40 50 60 70 80 90 100

0 0.05 0.1 0.15 0.2 0.25 0.3

Total Phosphorus (mg/L)Percentile Pass LVI

Region IX 25th Percentile
Region XII 25th Percentile A.

0 10 20 30 40 50 60 70 80 90 100

0 0.5 1 1.5 2 2.5 3 3.5 4

Total Nitrogen (mg/L)Percentile B.

0 10 20 30 40 50 60 70 80 90 100

0 20 40 60 80 100

Chlorophyll a (μg/L)Percentile C.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 71 The implementation of the criteria that EPA has recommended would result in the identification of many reference lakes (LVI ≥ 37) as impaired and, with a str ict application of the CWA, would result in TMDLs requiring significant reductions in nutrient availability to aquatic life. As noted for streams, reducing nutrient availability is no different than reducing the food supply for the organisms. This will a lter the biological integrity of the waterbody and limit its aquatic life, which is inconsistent with the goals of the CWA and federal regulations.

ESTUARIES

EPA published the document Nutrient Criteria Technical Guidance Manual: Estuarine and

Coastal Mar ine Waters in 2001 . T he guidance concluded that, because of differing geographic and climatic conditions among the East, Gulf, and West Coasts, uniform national criteria for estuarine and coastal waters are not appropriate, and that they should be develop ed at the

s tate, regional, or individual waterbody levels. Therefore, EPA did not propose

, nor is it currently in a position to propose

, CWA Section 304 ( a ) numeric nutrient criteria recommendations for estuaries. EPA currently has no basis upon which to promulgate nutrient

criteria for Florida estuaries.

WETLANDS

EPA published a final document

, Nutrient Criteria Technical Guidance Manual: Wetlands

, in

2007. While the document provided technical guidance for developing numeric nutrient criteria

for wetlan ds , EPA has not developed Section 304(a) recommendations upon which numeric nutrient criteria could be developed for Florida wetlands.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 72 

### Literature Cited

Buck, S., W. Dodds, J. Fisher, D. Hart, A. Parker, J. Stevenson, V. Watson

, and E. Welch.

2000. Nutr ient criteria technical guidance manual : Rivers and streams. EPA 822

- B

- 00

- 002. Washington, DC: U .S. Environmental Protection Agency.

Stephen, C.D

., D.I. Mount, D.J. Hansen, J.H. Gentile, G.A. Chapman, and W.A. Brungs. 1985. Guidelines for deriving n umerical national water quality criteria for the protection of aquatic organisms and their uses. Duluth, MN: U .S. E nvironmental Protection Agency, Office of Research and Development, Environmental Research Laboratories.

U.S. Environmental Protection Agen cy. 2000a. Ambient water quality criteria recommendations, information supporting the development of state and tribal nutrient criteria: Lakes and reservoirs in Nutrient Ecoregion IX. EPA 822

- B

- 00

- 011. Washington,

DC: Office of Water.

——— . 2000b. A mbient water quality criteria recommendations, information supporting the development of state and tribal nutrient criteria: Lakes and reservoirs in Nutrient Ecoregion

XII. EPA 822

- B

- 00

- 013. Washington, DC: Office of Water.

——— . 2000c. Ambient water quality criteria recommendations, information supporting the development of state and tribal nutrient criteria: Lakes and reservoirs in Nutrient Ecoregion

XIII. EPA 822

- B

- 00

- 014. Washington, DC: Office of Water.

——— . 2000d. Ambient w ater q uality c r iteria r ecommendations, i nformation s upporting the

d

evelopment of s tate and t ribal n utrient c riteria: Rivers and s treams in Nutrient Ecoregion

IX. EPA 822

- B

- 00

- 019. Washington, DC: Office of Water.

——— . 2000e. Ambient water quality criteria recommen dations, information supporting the development of state and tribal nutrient criteria: Rivers and streams in Nutrient Ecoregion

XII. EPA 822

- B

- 00

- 021. Washington, DC: Office of Water.

———

. 2001. Nutrient criteria technical guidance manual: Estuarine and coastal marine

waters. EPA

- 822

- B

- 01

- 003 . Washington, DC: Office of Water.

———

. 2007. Nutrient criteria technical guidance manual: Wetlands

. EPA

- 822

- R

- 07

- 004

. Washington, DC: Office of Water.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 73 

## Appendix B : Selection of Benchmark Sites (Chara cterized by Low Levels of Human Disturbance) U sing the LDI Index

Prepared by the Florida Department of Environmental Protection

, Water Quality Standards and Special Projects Program

Brown and Vivas (2003) have developed a n LDI to estimate the intensity of human land use based on nonrenewable energy flow. The a pplication of the LDI is based on the ecological principle that the intensity of human

- dominated land uses in a landscape affect ecological processes of natural communities. The more intense the activ ity, the greater the effect on ecological processes. Natural landscapes with little or no agricultural or urban development will likely have intact ecological systems and processes. The intended use of the LDI was as an

index of the HDG

.

The LDI is a lan d use

– based index of potential human disturbance calculated using coefficients corresponding to specific land use categories within drainage basins. The LDI coefficients were quantified using emergy 3

LDI Total = **Σ** (LDC i * %LU i ) use per unit area per time (Brown and Vivas, 2003). Br own and colleagues collected energy consumption data from billing records and literature sources, for energies such as electricity, fuels, fertilizers, pesticides, and water (both public water supply and irrigation). Because the LDI was meant to be a meas ure of human disturbance, only nonrenewable energies were used in the calculation. Natural systems were assigned a nonrenewable empowerment density of 0 sej/ha·yr

. 1 The LDI coefficients were calculated as the natural log of the empower densities normaliz ed on a scale from 1 to 10. LDI coefficients for natural lands equal 1.0 and a LDI coefficient of 10.0 is associated with the highest intensity land uses ( e.g., central business district or power plant).

The LDI is calculated as the area

- weighted value of the land uses within an area of influence. Using the land use coefficients and the percent area occupied by each land use as determined by GIS land use coverages, the LDI is calculated as follows:

Where,

LDI Total = L DI Index f or the area of influence

%LU i = percent of total area of influence in land use i
LDC i = LDI coefficient for land use i

Brown and Vivas (2003) and Fore (2004) evaluated various methods for calculating the LDI, including distance weighting and the area of influence. Brown and Vivas (2003) evaluated the differences in LDIs calculated using 100, 200, and 500 m buffer differences around drainage basins for wetlands. They reported no significant difference between LDIs calculated using

buffer distances of ei ther 100 or 200 m ; however, LDIs calculated using a 500 m buffer were different from those determined using either the 100 or 200 m distances in some cases. Additionally, they found that the LDIs determined using buffer distances of either 100 or 200 m

we re better able to predict the Wetland Biological Integrity (S FWMD ’s Wetland Rapid

Assessment Procedure [ WRAP ] ).

3 “ Emergy ” is energy that has been corrected for different qualities. Its unit is expressed as the solar emergy joule (sej). The units for quantifying the intensity of human activity are therefore sej/ha•yr

- 1 (empower density).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 74 Brown and Vivas (2003) also compared distance

- weighted and area

- weighted LDIs. They found no significant difference between the two methods a nd concluded that, since the time to

calculate an area

- weighted LDI was considerably less, the area

- weighted method was the most efficient method to calculate an LDI. Fore (2004) evaluated the effect of upstream catchment distance on the LDI for streams, in order to determine which spatial scale was a better predictor of site condition. She compared a LDI calculated as 100 m buffers around the streams both 10 km upstream of sampling points and for the entire upstream catchment area (watershed). The

LDIs calculated using the two distances were both highly correlated with each other and almost equally correlated with Florida’s SCI of stream macroinvertebrate biological integrity.

EPA guidance (2000 a, 2000b, 2000c, 2000d, and 2000e ) states that reference r eaches are relatively undisturbed stream segments that can serve as examples of the natural biological integrity of a region. Because reference reaches should be both minimally disturbed by anthropogenic influences and support valued ecologic al attributes (healthy populations of flora and fauna), the metrics used to select reference reaches need to be correlated with both the degree of human disturbance influencing the reach as well the biological or ecological health of the system. As discussed above, th e LDI was developed as a direct and objective measure of

human disturbance. I t has also bee n shown to be a reliable predic tor of pollutant loading ( Figure B

- 1 )

. Furthermore, the LDI has been demonstrated in multiple cases and across multiple waterbody ty pes to be an effective predictor of biological health.

Brown and Reiss (2006) suggested an LDI breakpoint of less than or equal to 2.0 to identify minimally disturbed sites and an LDI of greater than 2.0 to designate areas with increasing

levels of human disturbance based on an evaluation of diatom, macrophyte

, and macroinvertebrate assemblages ( i.e., Florida Wetland Condition Index [ FWCI ] ) in 193 depressional wetlands in Florida. The study divided wetlands into four groups for analysis (Group 1

– LDI = 1 .0; Group 2

– 1.0 < LDI ≤ 2.0; Group 3

– 2.0 < LDI ≤ 3.0; and Group 4

– LDI > 3.0). Statistical comparisons (2

- sample t

- test and Fisher’s one

- way multiple comparison) showed that there were no significant differences in diatom, macrophyte, or macroinverte brate
FWCI scores for LDI G roups 1 and 2 ( Table B

- 1 and Figure B

- 2 ). Additionally, G roups 3 and 4 (LDI >2) were found to be significantly different from G roups 1 and 2 (LDI < 2). Brown and Reiss (2006) concluded that an LDI of 2.0 represented a very cons ervative breakpoint between potentially disturbed sites and reference conditions.

The LDI has been also shown to be an effective predictor of stream macroinvertebrate biological integrity. Fore (2004) demonstrated a strong correlation (Spearman’s r=

- 0.60, p<0.01) between the LDI and the SCI ( Figure B

- 3 ). Furthermore, many of the 10 biological metrics that go into

the SCI , particularly p ercent sensitive taxa

, exhibit a strong correlation with the LDI ( Figure

B

- 4 ).

Niu (2004) provided a nother example of th e relationship between LDI and biologic heath. He evaluated breakpoints in lake chlorophyll a concentrations relative to LDI in 547 Florida l akes using change point analysis and found statistically significant change points in median lake chlorophyll a co ncentrations at LDI values of 1.9 and 6.3 ( Figure B

- 5 ).

As discussed above, the LDI was specially designed as a metric of human disturbance. LDI values of less than 2.0 are indicative of areas with very minimal levels of human disturbance. Although it wo uld be ideal to incorporate direct measures of biological health into the selection

of benchmark sites, this is not currently possible given the paucity of paired nutrient and biological data for the Lake Okeechobee Tributaries TMDL

, determined based on th e selected analysis method. Since it has been demonstrated that the LDI is highly correlated with multiple measures of biological health, the use of the LDI alone is deemed appropriate and adequate forState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 75 the selection of benchmark sites. Further, across mu ltiple waterbody types and multiple trophic levels, a n LDI of 2.0 has been shown to be a biologically significant breakpoint that can be used to distinguish benchmark conditions from potentially disturbed areas. Therefore, a n LDI of 2.0

or less is a conse rvative criterion that can appropriately and reliably be used to identify minimally disturbed benchmark sites.



### Table B

- 1

. Comparison of FWCI scores using Fisher’s one

- way multiple comparison test for three separate species assemblages (diatoms, macrophyte s, and macroinvertebrates) for depressional palustrine

wetlands

From Brown and Reiss (2006)

.

LDI Group Diatom FWCI Macrophyte FWCI Macroinvertebrate

FWCI

Group 1 LDI = 1.0 84.9 (15.2) a 85.1 (9.1) a 66.8 (17.1) a

Group 2 1.0 < LDI ≤ 2.0 80.4 (17.8) a 80.3 (13.4) a 65.9 (18.0) a

Grou p 3 2.0 < LDI ≤ 3.0 64.4 (18.9) b 56.8 (20.3) b 44.3 (22.1) b

Group 4 LDI > 3.0 35.5 (25.9) c 26.5 (21.7) c 34.0 (18.4) b

Notes: Group values represent mean (standard deviation).

M e ans in the same column followed by the same letter are not significantly different at α = 0. 05 using Fisher’s least significant difference ( LSD ) procedure

.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 76 

### Figure B

- 1. Area

- weighted LDI I ndex versus phosphorus pollutant load in 64 hydrologic units (su bwatersheds) of the St. Marks River watershed

.

R e

- created from Brown and Vivas ( 200 3 ).



### Area Weighted LDI 0 1 2 3 4 5 6 7 8 9 10Pollutant Load (kg P/ha·yr-1)



### 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 

### y=-0.49x-0.29

r 2 =0.90State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 77 

### Figure B

- 2. Box plot comparison of macroinvertebrate FWCI scores among LDI

groups , including Group 1 (LDI = 1.0), Group 2 (1.0 < LDI ≤ 2.0), Group 3 (2.0 < LDI ≤ 3 .0), and Group 4 (LDI > 3.0)

.

Boxes represent the 25 th to 75 th quartile range, circles represent group mean values, and horizontal lines represent median values (from Brown and Reiss, 2006).



### Figure B

- 3. Box plot comparison of SCI scores and LDI values c alculated based on a 100 m buffer area extending 10 km upstream of the sample pointMacroinvertebrateFWCI

4 3 2 1 100

80

60

40

20

0



## LDI Range 1.0 - 1.9 2.0-3.9 4.0 - 5.9 >6Stream Condition Index



## 0 20 40 60 80 100State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 78 

### Figure B

- 4

. Comparison of average number of sensitive stream macroinvertebrate taxa for sites within different LDI groups

The number of sensitive taxa from streams wi th LDIs < 2.0 was significantly greater than for streams with higher LDIs (Kruskall

- Wallis p <0.0001).



## LDI Range 1.0-1.9 2.0-3.9 4.0-5.9 >6.0Average Number of Sensitive Taxa (n)



## 0 2 4 6 8 10 12 14 16

LDI 0 2 4 6 8 10Average Number of Sensitive Taxa (n)

0 2 4 6 8 10 12 14 16

(Spearman’s r=-0.50, p<0.001)State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 79 

### Figure B

- 5

. Log of lake median chlorophyll **a** concentrations versus LDI

Two change points were detected. The first was detected at an LDI = 1.9 with a bout 80% confidence, and a second

was detected at an LDI = 6.3 with about 95% confidence.



### LDILog of Median of Chl-a



### 2 4 6 8-1012345State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 80 

### Literature Cited

Brown, M.T.

, and K.C. Reiss. 2006. Proposed breakpoint of LDI < 2.0 for determining minimally affected reference conditions for water bodies

. G ainesville, FL: Center for Environmental Policy, Department of Environmental Engineering Sciences, University of

Florida. Technical r eport submitted to the Florida Department of Environmental Protection.

Brown, M.T.

, and M.B. Vivas. 2003. A Landscape D evelopment Intensity Index. Gainesville,

FL: Center for Environmental Policy, Department of Environmental Engineering Sciences, University of Florida. Technical r eport submitted to the Florida Department of

Environmental Protection.

Fore, L.S. 2004. D evelopment and testing of biomonitoring tools for macroinvertebrates in

Florida streams

. Statistical Design, Se a ttle

, WA. Final report submitted to the Florida Department of Environmental Protection

Niu, X. 2004. Change point analysis of the chlorophyl l

- a and LDI data from the IWRM Status Network Cycle 1 lakes study

. Tallahassee, FL: Department of Statistics, Florida State University. Technical r eport submitted to the Florida Department of Environmental

Protection.

Niu, X., P. Lin., and D. Meeter. 2 000. Detecting change points in the species composition and water quality data of WCA2A. Tallahassee, FL: Department of Statistics, Florida State University. Technical r eport submitted to the Florida Department of Environmental

Protection.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 81 

## Appendix C

. Peninsular Nutrient Benchmark Summaries

Nutrient Benchmark Site Summary

Bee Branch

STORET Station 28020299FTM

Land Use

This station was considered to be a candidate reference site based on the Landscape Development Intensity Index
score of 1.64, su ggesting benign human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with small areas of citrus and field/pasture obser ved beyond the forested buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photograph of Bee Branch (Station 28020299FTM) showing watershed vicinity and land use. The headwaters drain an area dominated by pine flatw oods, prairie, and wetlands.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 82

DOQQ 2004 aerial l photograph of Bee Branch (Station 28020299FTM) showing close

- up of sampling site. An extensive forested riparian zone was evident of both sides of the system.

Photographs of Bee Branch (Station 28020299 FTM).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 83 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 147 Hydrologic Score 3

LDI Score 1.64

SCI Score 49 A Total Phosphorus Geometric Mean (mg/L) 0.080 Total Nitrogen Geometric Mean (mg/L) 1.13

The habitat assessmen t scored in the “Optimal” range. The Stream Condition Index scored in the “Healthy” category, exhibiting a diverse assemblage of sensitive invertebrates and indicating the site is clearly meeting the Class III designated use.

Algal Community Stricture Periphyton Community Composi tion

% Composition

% Bacillariophyta 91.33 % Chlorophycota 2.67 % Euglenophycota 0.67 % Cyanophycota 4.67

Number of Taxa 60

Minimal periphyton growth was observed at the site, which would allow for optimal substrate use by benthic invertebrate and fish communities. Of the 60 algal taxa observed, the majority of the periphyton community was composed of diatoms. No problematic filamentous algal growth was found.

Overall Reference Site Conclusion:

Experienced FDEP scient ists conducted a series of observations and measurements (habitat assessment, hydrology, local land use, and algal community) at Bee Branch. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropoge nic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota which demonstrate full support of the most sensitive d esignated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 84 Nutrient Reference Site Summary

Blackwater Creek at State Road 44A STORET Station ALT_BWC44 (20010455)

Land Use

This station was considered to be a candidate reference site based on the Landscape Development Intensity Index score of 1.09, suggesting benign human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the majority o f the watershed land use was forest/natural, with small areas of silviculture, and field/pasture observed beyond an extensive forested riparian buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photograph of Blackw ater Creek at State Road 44A (Station BWC44 or 20010455) showing watershed vicinity and land use. The system originates in Lake Norris, an undeveloped lake surrounded by wetland.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 85

DOQQ 2004 aerial photograph of Blackwater Creek at State Road 44A (Statio n BWC44 or 20010455) showing

close

- up of sampling site. An extensive forested riparian zone was evident on both sides of the system.

Photographs of Blackwater Creek at State Road 44AState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 86 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 125 Hydrologic Score 2

LDI Score 1.09

SCI Score 77 A Total Phosphorus Geometric Mean (mg/L) 0.050 Total Nitrogen Geometric Mean (mg/L) 1.60

The habitat assessment scored in the “Optimal” range, and the Stream Condition Index sco red in the “Exceptional” category, indicating an unusually diverse assemblage of sensitive invertebrates, definitively supporting the Class III designation.

Algal Community Stricture Periphyton Community Composition

% Composition

% Bacillariophyta 93.0 % Chlorophycota 0 % Cryptophycophyta 0 % Cyanophycota 7.0

Number of Taxa 45

Minimal periphyton growth was observed at the site, which would allow for optimal substrate use by benthic invertebrate and fish communities. Of the 45 algal taxa observed, the majority of the periphyton community was composed of diatoms. No problematic filamentous algal growth was found.

Overall Reference Site Conclusion:

Experienced FDEP scientists conducted a series of observations and measurements (hydrology, habitat assessment, local land use, algal and macroinvertebrate communities) at Blackwater Creek at State Road 44A. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropogenic stressors

and that it clearl y maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota which demonstrate full support of the most sensitive designated use (propagation and m aintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 87 Nutrient Benchmark Site Summary Blackwater Creek upstream of Carter Prop Bridge

STORET Station BWCCPB / 20010536

Land Use

This station was considered to be a candidate reference site based on the Landscape Development Intensity Index score of 1.31, suggesting benign human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the majority of the watershed land u se was forest/natural, with small areas of silviculture, and field/pasture observed beyond an extensive forested riparian buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photograph of Blackwater Creek upstream of Carter Prop Bridge (Station BWCCPB) showing watershed vicinity and land use. The system originates in Lake Norris, an undeveloped lake surrounding by

wetland.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 88 DOQQ aerial photograph of Blackwater Creek upstream of Carter Prop Bridge (Station BWCCPB) sh owing close

up of sampling site. An extensive forested riparian zone was evident of both sides of the system.

Photographs of Blackwater Creek upstream of Carter Prop BridgeState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 89 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 130 Hydrologic Score 2

LDI Score 1.31 Total Phosphorus Geometric Mean (mg/L) 0.054 Total Nitrogen Geometric Mean (mg/L) 1.28

The habitat assessment scored in the “Optimal” range. High water caused by recent rains made Stream Condition

In dex sampling inappropriate according to DEP standard operating procedures. Results from a Biorecon that was performed 2/7/2007 demonstrated that this site scored in the “healthy” range, indicating that the Class III designation is being fully supported.

Algal Community Stricture Periphyton Community Composition

% Composition

% Bacillariophyta 72.43 % Chlorophycota 15.28 % Cryptophycophyta 0.33 % Cyanophycota 7.31 % Euglenophycota 2.99

Number of Taxa 72

Very little periphyton was observed at the site, which would allow optimal substrate use by macroinvertebrates. No nuisance algal growth was found. Of the 72 algal taxa observed, the majority of the periphyton community was composed of diatoms.

.

Overall Reference Site Conclusion:

Experienc ed FDEP scientists conducted a series of observations and measurements (hydrology, local land use, and algal communities) at Blackwater Creek, upstream of Carter Prop Bridge. Based on our analyses, the Department

concluded that the site was influenced onl y by very low levels of anthropogenic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota which demonstrate fu ll support of the most sensitive designated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 90 Nutrient Benchmark Site Summary Cypress Branch above 78

STORET Station GLA630GS

Land Use

This station was consid ered to be a candidate reference site based on the Landscape Development Intensity Index score of 1.21 suggesting benign human influences in the watershed. During the site visit, aerial photographs were

examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with areas of citrus and field/pasture observed beyond an extensive forested riparian buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photograph of Cypress Branch (Station GLA630GS) showing watershed vicinity and land use. The stream originates in an area of prairie, flatwoods, and swamp.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 91

DOQQ 2004 aerial photograph of Cypress Branch (Station GLA630GS) showing close

- up of sampling site. An extensive ripar ian forested zone is generally present on both sides of the system throughout the watershed, with a

minimum of a 75

- 100 m buffer.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 92 Photograph of Cypress Branch (Station GLA630GS).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 93 Parameter Habitat, Biological and Water Quality Data

Value

Habitat As sessment 134 Hydrologic Score 2

LDI Score 1.21

SCI Score 63 A Total Phosphorus Geometric Mean (mg/L) 0.131 Total Nitrogen Geometric Mean (mg/L) 1.97

The habitat assessment scored in the “Optimal” range, and the Stream Condition Index scored in the “ Healthy” category, indicating a diverse assemblage of sensitive invertebrates, and fully supporting the Class III designation.

Algal Community Stricture Periphyton Community Composition

% Composition

% Bacillariophyta 91.33 % Chlorophycota 0 % Cryptop hycophyta 0 % Cyanophycota 8.67

Number of Taxa 48

Very little periphyton was observed at the site, which would allow optimal substrate use by macroinvertebrates. No nuisance algal growth was found. Of the 48 algal taxa observed, the majority of the per iphyton community was composed of diatoms.

Overall Reference Site Conclusion:

Experienced FDEP scientists conducted a series of observations and measurements (habitat assessment, hydrology, and local land use) at Cypress Branch. Based on our analyse s, the Department concluded that the site was influenced only by very low levels of anthropogenic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflective of minimally disturbed con ditions, they are associated with biota which demonstrate full support of the most sensitive designated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 94 Nutrient Benchmark Site Summary

Econlockhatchee River a t Snowhill Road

STORET Station ECH

Land Use

This station was considered to be a candidate reference site based on the Landscape Development Intensity Index score of 1.14, suggesting benign human influences in the watershed. During the site visit, aeri al photographs were examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with small areas of silviculture, and field/pasture observed beyond the forested buffer zone.

DOQQ 2004 aerial photograph of Econlockhatchee River at Snowhill Road (Station ECH) showing watershed vicinity and land use. The system originates in the Econlockhatchee River Swamp, an extensive wetland area.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 95 DOQQ 2004 aerial photograph of Econlockhatchee River at Snowhill Road (S tation ECH) showing close

- up of sampling site. An extensive forested riparian zone was evident of both sides of the system.

Photographs of Econlockhatchee River at Snowhill RoadState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 96 Parameter Habitat, Biological and Water Quality Data

Value

H abitat Assessment 106 Hydrologic Score 2

LDI Score 1.14

SCI Score 52 A Total Phosphorus Geometric Mean (mg/L) 0.098 Total Nitrogen Geometric Mean (mg/L) 0.93

The habitat assessment score of 106 placed this site in the high “Suboptimal” range. The S tream Condition Index score of 52 was in the “Healthy” category, exhibiting a diverse assemblage of sensitive invertebrates and indicating the site is clearly meeting the Class III designated use.

Algal Community Structur e Periphyton Community Composition

% Composition

% Bacillariophyta 90.31 % Chlorophycota 1.38 % Cryptophycophyta 0 % Cyanophycota 8.3

Number of Taxa 53

Minimal periphyton growth was observed at the site, which would allow for optimal substrate use by benthic

invertebrate and fish c ommunities. Of the 53 algal taxa observed, the majority of the periphyton community was composed of diatoms. No problematic filamentous algal growth was found.

Overall Reference Site Conclusion:

Experienced FDEP scientists conducted a series of obser vations and measurements (habitat assessment, hydrology, local land use, and algal and macroinvertebrate communities) at Econlockhatchee River at Snowhill Road. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropogenic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota which demonstrate full support of the most sensitive designated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 97 Nutrient Benchmark Site Summary Little Orange Creek below Cabbage Creek

STORET Station LOCBCC

Land Use

This station was consid ered to be a candidate reference site based on the Landscape Development Intensity Index score of 1.54, suggesting benign human influences in the watershed. During the site visit, aerial photographs were

examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with small areas of silviculture, and field/pasture observed beyond an extensive forested riparian buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photogra ph of Little Orange Creek below Cabbage Creek (Station LOCBCC) showing watershed

vicinity and land use. Little Orange Creek originates from Little Orange Lake, a completely undeveloped system surrounded by forest, and associated wetlands.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 98 DOQQ 2004 aer ial photograph of Little Orange Creek below Cabbage Creek (Station LOCBCC) showing close

- up of sampling site. An extensive riparian forested wetland buffer is present on both sides of the system.

Photographs of Little Orange Creek below Cabbage Cree kState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 99 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 132 Hydrologic Score 2

LDI Score 1.54

SCI Score 89 A Total Phosphorus Geometric Mean (mg/L) 0.067 Total Nitrogen Geometric Mean (mg/L) 0.70

The habitat assessme nt scored in the “Optimal” range, and the Stream Condition Index scored in the “Exceptional” category, indicating an unusually diverse assemblage of sensitive invertebrates, definitively supporting the Class III designation.

Algal Community Stricture Periphyton Community Compositi on

% Composition

% Bacillariophyta 84.52 % Chlorophycota 5.16 % Cryptophycophyta 0 % Cyanophycota 10.32

Number of Taxa 54

Minimal periphyton growth was observed at the site, which would allow for optimal substrate use by b enthic invertebrate and fish communities. Of the 54 algal taxa observed, the majority of the periphyton community was composed of diatoms. No problematic filamentous algal growth was found.

Overall Reference Site Conclusion:

Experienced FDEP scientis ts conducted a series of observations and measurements (habitat assessment, hydrology, local land use, and algal and macroinvertebrate communities) at Little Orange Creek below Cabbage Creek. Based on our analyses, the Department concluded that the site w as influenced only by very low levels of anthropogenic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota whi ch demonstrate full support of the most sensitive designated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 100 Nutrient Benchmark Site Summary Little Orange Creek

STORET Station PUT308GS

Land Use

This statio n was considered to be a candidate reference site based on the Landscape Development Intensity Index score of 2.01, suggesting benign human influences in the watershed. During the site visit, aerial photographs were

examined and direct observations confir med that the majority of the watershed land use was forest/natural, with small areas of silviculture and field/pasture observed beyond an extensive forested riparian buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aeri al photograph of Little Orange Creek (Station PUT308GS) showing watershed vicinity and land

use. The stream originates from Little Orange Lake, an undeveloped system surrounded by forest and swamp.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 101 DOQQ 2004 aerial photograph of Little Orange Creek (Sta tion PUT308GS) showing close

- up of sampling site. An

extensive riparian forested buffer is generally present on both sides of the system throughout the watershed, with

one small clear

- cut area approaching within 75 m of the stream.

Photograph of Littl e Orange CreekState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 102 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 131 Hydrologic Score 2

LDI Score 2.01

SCI Score 75 A Total Phosphorus Geometric Mean (mg/L) 0.201 Total Nitrogen Geometric Mean (mg/L) 1.13

The habitat a ssessment scored in the “Optimal” range, and the Stream Condition Index scored in the “Exceptional” category, indicating an unusually diverse assemblage of sensitive invertebrates, definitively supporting the Class III designated use. This is one of the f ew peninsular sites where Plecopterans (stoneflies, known to be extremely sensitive to stress) are routinely found.

Algal Community Stricture Periphyton Community Composition

% Composition

% Bacillariophyta 86.6 % Chlorophycota 5.7 % Cryptophycophyta 0 % Cyanophycota 7.4

Number of Taxa 48

Minimal periphyton growth was observed at the site, which would allow for optimal substrate use by benthic invertebrate and fish communities. Of the 48 algal taxa observed, the majority of the periphyton communit y was composed of diatoms. No problematic filamentous algal growth was found.

Overall Reference Site Conclusion:

Experienced FDEP scientists conducted a series of observations and measurements (habitat assessment, hydrology, local land use, and algal and macroinvertebrate communities) at Little Orange Creek. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropogenic stressors and that it clearly maintained healthy biological assemblages. Thus , not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota which demonstrate full support of the most sensitive designated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 103 Nutrient Benchmark Site Summary

Moses Creek at US 1

STORET Station 27010050

Land Use

This station was considered to be a candidate reference site based on the Landscape Development Intensity Index score of 1.24, suggesting benig n human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with small areas of silviculture, and field/pasture observed bey ond the forested buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photograph of Moses Creek at US 1 (Station 27010050) showing watershed vicinity and land

use.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 104 DOQQ 2004 aerial photograph of Moses Creek at US 1 (Station 27010050) showing close

- up of sampling site. Moses Creek originates in an area of pine flatwoods and swamp. An extensive riparian forested buffer is present on both sides of the system.

Photograph of Moses Creek at US 1State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 105 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 138 Hydrologic Score 1

LDI Score 1.24

SCI Score 60 A Total Phosphorus Geometric Mean (mg/L) 0.081 Total Nitrogen Geometric Mean (mg/L) 1.03

The habitat assessment scored in the “Optimal” r ange. The Stream Condition Index score of 60 was in the “Healthy” category, exhibiting a diverse assemblage of sensitive invertebrates and indicating the site is meeting the Class III designated use.

Algal Community Stri cture Periphyton Community Composition

% Composition

% Bacillariophyta 14.33 % Chlorophycota 1.33 % Euglenophycota 1.67 % Cyanophycota 81.67

Number of Taxa 71

Minimal periphyton growth was observed at the site, which would allow for optimal substrate use by benthic

invertebrate and fish communities. Of the 71algal taxa observed, including 66 diatom taxa, the majority of the periphyton community was composed of blue

- green algae. No problematic filamentous algal growth was found.

Overall Reference Site Conclusion:

Experienced FD EP scientists conducted a series of observations and measurements (habitat assessment, hydrology, and local land use) at Moses Creek at US 1. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropog enic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota which demonstrate full support of the most sensitive designated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 106 Nutrient Benchmark Site Summary Orange Creek Upstream of Highway 21

STORET Station 21202

Land Use

This station was considered to be a candidate re ference site based on the Landscape Development Intensity Index score of 1.7, suggesting benign human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with small areas of silviculture and field/pasture observed beyond a forested riparian buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photograph of Orange Creek upstream of Highw ay 21 (Station 21202) showing watershed vicinity and land use. The stream originates from Orange Lake, an Outstanding Florida Water.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 107 DOQQ 2004 aerial photograph of Orange Creek upstream of HWY 21 (Station 21202) showing close

- up of sampling site. An e xtensive riparian forested wetland buffer is present on both sides of the system.

Photograph of Orange Creek upstream of Highway 21State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 108 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 121 Hydrologic Score 3

LDI Score 1.74

SCI Score 74 A Total Phosphorus Geometric Mean (mg/L) 0.125 Total Nitrogen Geometric Mean (mg/L) 1.43

The habitat assessment scored in the “Optimal” range, and the Stream Condition Index scored in the “Exceptional” category, indicating an unusually d iverse assemblage of sensitive invertebrates. This is one of the few peninsular sites where Plecopterans (stoneflies, known to be extremely sensitive to stress) are routinely found.

Algal Community Stricture Periphyton Community Composition

% Compositio n

% Bacillariophyta 90.38 % Chlorophycota 1.37 % Cryptophycophyta 0 % Cyanophycota 8.25

Number of Taxa 51

Minimal periphyton growth was observed at the site, which would allow for optimal substrate use by benthic

invertebrate and fish communities. Of the 51 algal taxa observed, the majority of the periphyton community was composed of diatoms. No problematic filamentous algal growth was found.

Overall Reference Site Conclusion:

Experienced FDEP scientists conducted a series of observations and m easurements (habitat assessment, hydrology, local land use, and algal and macroinvertebrate communities) at Orange Creek, upstream of Highway 21. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthr opogenic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota which demonstrate full support of the most sensit ive designated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 109 Nutrient Benchmark Site Summary

St. Johns River Near DeLand

STORET Station 2236000

Land Use

This station was considered to be a candidate refe rence site based on the Landscape Development Intensity Index score of 1.68, suggesting benign human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with small areas of silviculture, and field/pasture observed beyond the forested buffer zone.

DOQQ 2004 aerial photograph of St. John’s River near DeLand (Station 2236000) showing watershed vicinity and land use. The system originates from Blue Cypress Lake, a completely undeveloped system surrounding by forest

and wetlands.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 110

DOQQ 2004 aerial photograph of St. John’s River near DeLand (Station 2236000) showing close

- up of sampling site. An extensive riparian forested wetl and buffer is present on both sides of the system.

Photographs of St. John’s River near DeLandState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 111 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 128 Hydrologic Score 4

LDI Score 1.68

SCI Score NA Total Phosph orus Geometric Mean (mg/L) 0.078 Total Nitrogen Geometric Mean (mg/L) 1.39

The habitat assessment scored in the “Optimal” range. This system is characterized by very low flow, therefore Stream Condition Index sampling was inappropriate according to DEP standard operating procedures. Aquatic vegetation present was typical of sluggish, open systems and there were no nuisance plant issues.

Algal Community Stricture Periphyton Community Composition

% Composition

% Bacillariophyta 88.2 % Chlorophycota 2 .4 % Cryptophycophyta 0 % Cyanophycota 9.5

Number of Taxa 53

Minimal periphyton growth was observed at the site, which would allow for optimal substrate use by benthic invertebrate and fish communities. Of the 53 algal taxa observed, the majority of the periphyton community was composed of diatoms. No problematic filamentous algal growth was found.

Overall Reference Site Conclusion:

Experienced FDEP scientists conducted a series of observations and measurements (habitat assessment, hydrology,

loc al land use, and algal communities) at the St. Johns River near Deland. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropogenic stressors and based upon observations during the site visit, that no adverse algal or aquatic plant issues were present. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota which suggest support of the most sensitive designated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 112 Nutrient Benchmark Site Summary

Steven’s Branch off CR 204

STORET Station 27010070

Land Use

This station was considered to be a candidate reference site based on the Landscape Development Intensity Index score of 1.29, suggesting benign human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with small areas of silviculture, and field/pasture observed beyond an extensive forested riparian buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photograph of Steven’s Branch off CR 204 (Station 27010070) showing w atershed vicinity and land use. Steven’s Branch originates in an area of pine flatwoods, wetlands and prairie.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 113

DOQQ 2004 aerial photograph of Steven’s Branch off CR 204 (Station 27010070) showing close

- up of sampling site. An extensive riparian foreste d buffer is present on both sides of the system.

Photographs of Steven’s Branch off CR 204 (Station 27010070)State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 114 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 128 Hydrologic Score 3

LDI Score 1.29

SCI Score 76 A Total Phosphorus Geometric Mean (mg/L) 0.120 Total Nitrogen Geometric Mean (mg/L) 1.09

The habitat assessment scored in the “Optimal” range, and the Stream Condition Index scored in the “Exceptional” category, indicating an unusually diverse assemblage of sensitive invertebrates, definitively supporting the Class III designation.

Algal Community Stricture Periphyton Community Composition

% Composition

% Bacillariophyta 75.14 % Chlorophycota 3.39 % Cryptophycophyta 0 % Cyanophycota 21.47

Number of Taxa 66

Minimal periphyton growth was observed at the site, which would allow for optimal substrate use by benthic invertebrate and fish communities. Of the 66 algal taxa observed, the majority of the periphyton community was composed of diatoms. No pr oblematic filamentous algal growth was found.

Overall Reference Site Conclusion:

Experienced FDEP scientists conducted a series of observations and measurements (habitat assessment, hydrology, local land use, and algal and macroinvertebrate communities ) at Steven’s Branch off CR 204. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropogenic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrien t concentrations reflective of minimally disturbed conditions, they are associated with biota which demonstrate full support of the most sensitive designated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 115 Nu trient Benchmark Site Summary

Tosohatchee Creek @ WMA

STORET Station ORA331LV

Land Use

This station was considered to be a candidate reference site based on the Landscape Development Intensity Index score of 1.50, suggesting benign human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with small areas of silviculture and field/pasture observed beyond an extensive forest ed riparian buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photograph of Tosohatchee Creek (Station ORA331LV) showing watershed vicinity and land use. The stream originates in a swampy area adjacent to Tosohat chee Creek State Preserve.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 116 DOQQ 2004 aerial photograph of Tosohatchee Creek (Station ORA331LV) showing close

- up of sampling site. An extensive riparian forested wetland buffer is present on both sides of the system.

Photograph of Tosohatchee Creek (S tation ORA331LV).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 117 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 116 Hydrologic Score 1

LDI Score 1.50

SCI Score NA Total Phosphorus Geometric Mean (mg/L) 0.034 Total Nitrogen Geometric Mean (mg/L) 0.77

The habitat assessment scored in the high “Suboptimal” range, with water velocity being the lowest scoring parameter. The site was deemed inappropriate for SCI sampling due to the swamp

- like nature of the system and lack of water flow. Vegetation present was typical of minimally disturbed swamp systems.

Algal Community Stricture Periphyton Community Composition

% Composition

% Bacillariophyta 89.00 % Chlorophycota 0.33 % Euglenophycota 0.33 % Cyanophycota 10.33

Number of Taxa 56

Of the 56 algal taxa identifi ed, the majority of the periphyton community was composed of diatoms. No problematic filamentous algae were observed.

Overall Reference Site Conclusion:

Experienced FDEP scientists conducted a series of observations and measurements (habitat assessment , hydrology, algal community, and local land use) at Tosohatchee Creek. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropogenic stressors and that no adverse algal or aquatic plant

issues were present. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota which suggest support of the most sensitive designated use (propagation and maintenance of a healthy, well

- balanced popula tion of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 118 Nutrient Benchmark Site Summary

Waccasassa River above SR 24

STORET Station LEV502GS

Land Use

This station was considered to be a candidate reference site based on the Landscape Development Intensity Index
score of 1.23, su ggesting benign human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with small areas of silviculture, and field/pastur e observed beyond the forested riparian buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photograph of the Waccasassa River (Station LEV502GS) showing watershed vicinity and land use. The Wacasassa River origina tes in an area of hardwood swamp known as Devils Hammock.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 119

DOQQ 2004 aerial photograph of the Waccasassa River (Station LEV502GS) showing close

- up of sampling site.

Although there was some encroachment from a clear cut area near the site, extensive ripar ian forested wetland buffer is present on both sides for the majority of the system. Note that the forested buffer still exceeded approximately 75 m at minimum, and was generally several hundred m wide.

Photographs of the Waccasassa RiverState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 120 Parameter Habi tat, Biological and Water Quality Data

Value

Habitat Assessment 138 Hydrologic Score 1

LDI Score 1.23

SCI Score 69 A Total Phosphorus Geometric Mean (mg/L) 0.065 Total Nitrogen Geometric Mean (mg/L) 0.63

The habitat assessment scored in the high “Optimal” range, and the Stream Condition Index scored in the “Exceptional” category, indicating an unusually diverse assemblage of sensitive invertebrates, definitively supporting the Class III designation.

Alga l Community Stricture Periphyton Community Composition

% Composition

% Bacillariophyta 84.24 % Chlorophycota 0.32 % Cryptophycophyta 0 % Cyanophycota 15.43

Number of Taxa 46

Minimal periphyton growth was observed at the site, which would allow for optimal substrate use by benthic

i nvertebrate and fish communities. Of the 46 algal taxa observed, the majority of the periphyton community was composed of diatoms. Although some filamentous algal growth was found in a few small areas, it did not affect habitat suitability, as evidenced by the very good SCI score.

Overall Reference Site Conclusion:

Experienced FDEP scientists conducted a series of observations and measurements (habitat assessment, hydrology, local land use, and algal and macroinvertebrate communities) at the Waccasass a River. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropogenic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflect ive of minimally disturbed conditions, they are associated with biota demonstrated to be fully supportive of the designated use (healthy, well balanced populations of aquatic organisms).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 121 Nutrient Benchmark Site Summary Withlacoochee River at Stokes Ferry

STORET Station 3513

Land Use

This station was considered to be a candidate reference site based on the Landscape Development Intensity Index score of 1.82, suggesting benign human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the majority of the watershed land use was forest/natural, with small areas of silviculture, field/pasture, and residential uses observed beyond a forested riparian buffer zone. There are no point sour ce discharges upstream of the site.

DOQQ 2004 aerial photograph of Withlacoochee River at Stokes Ferry (Station 3513) showing watershed vicinity

and land use. The Withlacoochee River originates in the Green Swamp, a very large wetland with considerable areas in public ownership.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 122 DOQQ 2004 aerial photograph of Withlacoochee River at Stokes Ferry (Station 3513) showing close

- up of sampling site. An extensive riparian forested wetland buffer is present on both sides of the system.

Photographs of the Withlacoochee River at Stokes FerryState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 123 Parameter Habitat, Biological and Water Quality Data

Value

Habitat Assessment 153 Hydrologic Score 4

LDI Score 1.82

SCI Score 68 A Total Phosphorus Geometric Mean (mg/L) 0.043 Total Nitrogen Geometric M ean (mg/L) 0.86

The habitat assessment scored in the high “Optimal” range, and the Stream Condition Index scored in the “Exceptional” category, indicating an unusually diverse assemblage of sensitive invertebrates, definitively supporting the Class III d esignated use.

Algal Community Stricture Periphyton Community Composition

% Composition

% Bacillariophyta 90.24 % Chlorophycota 0.7 % Cryptophycophyta 0 % Cyanophycota 9.06

Number of Taxa 40

Moderate periphyton growth was observed at the site; how ever, substrate availability for benthic invertebrates was not problematic, as evidenced by the “exceptional” SCI score. Of the 40 algal taxa obser ved, the majority of the periphyton community was composed of diatoms. No problematic filamentous algal growth was found, despite the relatively open, sunny conditions characteristic of the site.

Overall Reference Site Conclusion:

Experienced FDEP sci entists conducted a series of observations and measurements (habitat assessment, hydrology, local land use, and algal and macroinvertebrate communities) at Withlacoochee River at Stokes Ferry. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropogenic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota de monstrated to be fully supportive of the designated use (healthy, well balanced populations of aquatic organisms).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 124 Nutrient Benchmark Site Summary

Withlacoochee River at Trails End

STORET Station FL0052000087500

Land Use

This station was considered t o be a candidate reference site based on the Landscape Development Intensity Index score of 1.34, suggesting benign human influences in the watershed. During the site visit, aerial photographs were examined and direct observations confirmed that the major ity of the watershed land use was forest/natural, with small areas of silviculture, field/pasture, and residential uses observed beyond the forested buffer zone. There are no point source discharges upstream of the site.

DOQQ 2004 aerial photograph of Withlacoochee River at Trails End (Station FL0052000087500) showing watershed vicinity and land use. The Withlacoochee River originates in the Green Swamp, a very large wetland with considerable areas in public ownership.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 125 DOQQ 2004 aerial photograph of Withlacoochee River at Trails End (Station FL0052000087500) showing close

- up of sampling site. An extensive riparian forested wetland buffer is present on both sides of the system.

Photographs of Withlacoochee River at Trails EndState of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 126 Parameter Habitat, Bio logical and Water Quality Data

Value

Habitat Assessment 118 Hydrologic Score 2

LDI Score 1.34

SCI Score NA Total Phosphorus Geometric Mean (mg/L) 0.059 Total Nitrogen Geometric Mean (mg/L) 1.01

The habitat assessment scored in the high “ Suboptimal” range. The SCI was not performed due to the morphology of the system in this area (lake

- like), which when coupled with low water levels, resulted in the system having no perceptible water velocity. Typical aquatic plants observed at the site i ncluded Taxodium distichum, Hydrocotyle

sp ., Panicum hemitomon, Myriophyllum heterophyllum, and Polygonum sp., indicating healthy conditions.

Qualitative Periphyton Sampling was not performed at this site, however minimal periphyton growth was observed,

w hich would allow for optimal substrate use by benthic invertebrate and fish communities. No problematic filamentous algal growth was found, despite the relatively open, sunny conditions characteristic of the site.

Overall Reference Site Conclusion:

Ex perienced FDEP scientists conducted a series of observations and measurements (habitat assessment, hydrology and local land use) at Withlacoochee River at Trails End. Based on our analyses, the Department concluded that the site was influenced only by ver y low levels of anthropogenic stressors and that no adverse algal or aquatic plant issues were present. Thus, not only are the nutrient concentrations reflective of minimally disturbed conditions, they are associated with biota which suggest support of th e most sensitive designated use (propagation and maintenance of a healthy, well

- balanced population of fish and wildlife).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 127 Nutrient Benchmark Site Summary

Withlacoochee River at SR 471

STORET Station WITHLACOORVR1

Land Use

This station was considered to be a candidate reference site based on the Landscape Development Intensity Index score of 1.45, suggesting benign human influences in the watershed. During the site visit, aerial photographs were

examined and direct observa tions confirmed that the majority of the watershed land use was forest/natural, with small areas of silviculture and field/pasture observed beyond an extensive forested riparian buffer zone. There are no point source discharges upstream of the site.

Ae rial photograph of Withlacoochee River at SR 471 (Station WITHLACOORVR1) showing watershed vicinity and landuse. The Withlacoochee River originates in the Green Swamp, an extensive wetland with considerable areas in public ownership.State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 1 28 Aerial photograph of Withlacoochee River at SR 471 (Station WITHLACOORVR1) showing close

- up of sampling site. An extensive riparian forested wetland buffer is present on both sides of the system.

Photograph of Withlacoochee River at SR 471 (Station WITHLACOORVR1).State of Florida Numeric Nutrient Criteria Development Plan March 2009

Florida Department of Environmental Protection 129 Parameter Ha bitat, Biological and Water Quality Data

Value

Habitat Assessment 119 Hydrologic Score 2

LDI Score 1.45

SCI Score 46 A Total Phosphorus Geometric Mean (mg/L) 0.080 Total Nitrogen Geometric Mean (mg/L) 1.68

The habitat assessment scored i n the high “suboptimal” range due to no water velocity . The Stream Condition Index was not performed during this site visit due to low water levels and minimal stream velocity. However, sites both upstream (station 33449) and downstream (station 34401) of the sampling location and within the same WBID received “healthy” SCI designations in 2007, (51 A and 40 A, respectively) i ndicating that the water quality is fully supporting the Class III designated use. These scores were averaged for the above table.

Algal Community Stricture Periphyton Community Composition

% Composition

% Bacillariophyta 85.95 % Chlorophycota 1.3 % Cryptophycophyta 0 % Cyanophycota 12.1 % Euglenophycota 0.7

Number of Taxa 61

Minimal periphyton growth was observed at the s ite, which would allow for optimal substrate use by benthic invertebrate and fish communities. Of the 61 algal taxa observed, the majority of the periphyton community was composed of diatoms. No problematic filamentous algal growth was found.

Overall Re ference Site Conclusion:

Experienced FDEP scientists conducted a series of observations and measurements (habitat assessment, hydrology, local land use, and algal and macroinvertebrate communities) Withlacoochee River at SR 471. Based on our analyses, the Department concluded that the site was influenced only by very low levels of anthropogenic stressors and that it clearly maintained healthy biological assemblages. Thus, not only are the nutrient concentrations reflective of minimally disturbed condi tions, they are associated with biota demonstrated to be fully supportive of the designated use (healthy, well balanced populations of aquatic organisms).