Implementation of 

Florida’s Numeric Nutrient Standards

Document Submitted to EPA in Support of the Department of 

Environmental Protection’s Adopted Nutrient Standards for 

Streams, Spring Vents, Lakes, and Selected Estuaries

April 2013
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TABLE OF CONTENTS

Purpose of Document............................................................................................................ 1

Background........................................................................................................................... 1

The Hierarchical Approach..................................................................................................... 1

Nutrient Criteria for Lakes ..............................................................................................................2

Nitrate-Nitrite Criterion for Spring Vents.........................................................................................4

Using Measures of Flora and Fauna and Regional Nutrient Thresholds in Streams............................5

Stream Definition...................................................................................................................5

Implementation of NNC in Streams ........................................................................................6

Floral Evaluation for Determining Achievement of NNC ..........................................................8

Evaluating Algal Mats...........................................................................................................10

RPS Decision Key...................................................................................................................10

Evaluating Changes in Species Composition ..........................................................................11

Algal Species Composition Decision Key...............................................................................12

Evaluating the Presence or Absence of Nuisance Macrophyte Growth...................................12

LVS Decision Key...................................................................................................................13

Evaluating Algal Blooms, Chlorophyll a, and Phytoplankton Taxonomic Data.........................14

Chlorophyll/Algal Bloom Decision Key .................................................................................15

Floral Measures Summary....................................................................................................16

Faunal Evaluation for Determining Achievement of NNC.......................................................16

Examples of a Weight-of-Evidence Approach for Determining Achievement 

of Nutrient Criteria...............................................................................................................17

Stream Sampling Locations and Other Environmental Considerations ...................................20

Nutrient Criteria in Estuaries.........................................................................................................21

Decision Matrix and Examples for Implementing the Hierarchical Process............................ 21

Hierarchies 1 and 2.......................................................................................................................24

Examples of Hierarchy 1.......................................................................................................24

Examples of Hierarchy 2.......................................................................................................24

Hierarchy 3...................................................................................................................................25

Examples of Hierarchy 3.......................................................................................................26
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Waterbody Types and Cases with Insufficient Information.............................................................28

Other Components of NNC............................................................................................................28

NNC and Protection of Downstream Waters..................................................................................29

Water Quality Modeling.......................................................................................................29

Issuance of NPDES Permits...................................................................................................29

Evaluation of Trends............................................................................................................30

Trend Test Summary ............................................................................................................32

Discussion of TMDLs as NNC .........................................................................................................33

Discussion of Site Specific Alternative Criteria as NNC....................................................................34

Implementing the NNC Revisions to the Impaired Waters Rule (Chapter 62-303, F.A.C.)....... 35

Assessment of Estuaries................................................................................................................40

Assessment of Waterbodies with Interpretations of the NNC Expressed as Loads or Delivery 

Ratios ..............................................................................................................................41

Impaired Waters Rule Assessment Summary ........................................................................41

Surface Water Discharge Wastewater Permits..................................................................... 42

WQBEL Procedures for Each Tier of the Hierarchy ................................................................. 43

Basic Information Needs for Distinguishing Flowing Waters Under 62-302.200(36), F.A.C..... 49

General Information.....................................................................................................................50

Non-Perennial Water Segments....................................................................................................50

Vascular Plants as Indicators................................................................................................50

Macroinvertebrates as Indicators.........................................................................................51

Tidally Influenced Segments .........................................................................................................54

Water Management Conveyances................................................................................................55

Delineation..........................................................................................................................56

Primary Water Management Purpose...................................................................................56

Physical Alteration that Limits Habitat..................................................................................56

Appendix A. Minimally Disturbed and Healthy Streams ................................................................58

Table A-1. List of healthy streams (passing SCI) used to inform RPS expectations.............58

Table A-2. List of benchmark streams used to establish RPS and LVS 

expectations.................................................................................................................64

Table A-3. List of healthy streams (passing SCI) used to inform stream 

chlorophyll a expectations. ..........................................................................................65
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Table A-4. List of benchmark streams used to establish stream chlorophyll a 

expectations.................................................................................................................73
1 

PURPOSE OF DOCUMENT

This document describes how numeric nutrient standards in Chapters 62-302 (Water Quality Standards) 

and 62-303 (Identification of Impaired Surface Waters), Florida Administrative Code (F.A.C.), are

implemented by the Department of Environmental Protection (Department). The major topics include 

the hierarchical approach used to interpret the narrative nutrient criterion (NNC) on a site-specific basis; 

a summary of the criteria for lakes, spring vents, streams and estuaries; floral measures and the weight 

of evidence approach in streams; example scenarios for how the criteria will be implemented in the 

303(d) assessment process; and a description of how the Water Quality Based Effluent Limitation 

(WQBEL) process is used to implement the nutrient standards in wastewater permitting. Finally, 

because of the complexity associated with assessing nutrient enrichment effects in streams, a summary 

of the weight-of-evidence evaluation involving flora, fauna, and Nutrient Thresholds is provided. 

BACKGROUND

Nutrients are naturally present in aquatic systems and are necessary for the proper functioning of 

biological communities. Nutrient effects on aquatic ecosystems are moderated in how they are 

expressed by many natural factors (e.g., light penetration, hydraulic residence time, presence of 

herbivore grazers and other food web interactions, and habitat considerations). As a result, determining 

the appropriate protective nutrient regime is largely a site-specific undertaking, requiring information 

about ecologically relevant responses. 

THE HIERARCHICAL APPROACH

The NNC in paragraph 62-302.530(47)(b), F.A.C., states that “in no case shall nutrient concentrations of 

a body of water be altered so as to cause an imbalance in natural populations of aquatic flora or fauna.” 

The method for numerically interpreting this NNC, on a site-specific basis, is provided in Rule 62-

302.531, F.A.C, using a hierarchical process (Figure 1). This hierarchical scheme specifies a prioritization 

for determining the numeric nutrient criteria that apply to a given waterbody. 

The Rule’s hierarchical approach gives preference to site-specific analyses that result in a numeric 

interpretation of the NNC. Site specific interpretations are generally deemed superior to more broadly 

applicable interpretations of the NNC because of the many natural factors affecting the expression of 

nutrient loadings on a given waterbody. Beginning at the top of Figure 1, if there is a site specific 

interpretation of the narrative, such as a Total Maximum Daily Load (TMDL), Site Specific Alternative 

Criterion (SSAC), Water Quality Based Effluent Limitation (WQBEL), or other Department-approved 

action that numerically interprets the narrative criterion (e.g., Reasonable Assurance derived values), 

that numeric interpretation is the applicable nutrient criterion1

. These numeric interpretations of the 

narrative criterion must establish the total allowable load or ambient concentration for at least one 

nutrient that represents achievement of a healthy, well balanced aquatic community. Each nutrient (TP 

 

1 Consistent with the Clean Water Act, these site-specific interpretations will be submitted to EPA for review.
2 

and TN) is interpreted independently using this hierarchical approach; if the site-specific interpretation 

only addresses one nutrient, then the generally applicable numeric interpretations in subsections 62-

302.531(2) and (3), F.A.C., will apply for the other nutrient.

If a hierarchy 1 interpretation is not available, the Rule’s hierarchical approach then gives preference to 

numeric nutrient values based on quantifiable stressor-response relationships between nutrients and 

biological response (i.e., springs and lakes). If no quantifiable stressor-response relationship has been 

established, such as is the case for Florida streams, reference-based Nutrient Thresholds, in conjunction 

with biological information, are used to determine the applicable interpretation of the NNC. For those 

waters without a numeric interpretation under any of these approaches, the NNC continues to apply to 

the waterbody.

Figure 1. The hierarchy for numerically interpreting the NNC.

Nutrient Criteria for Lakes

The lakes criteria were based on a strong stressor-response relationship between nutrients (TN and TP) 

and phytoplankton response (chlorophyll a). The lakes chlorophyll criteria were derived using multiple 

lines of evidence, and result in maintaining naturally low nutrient lakes in an oligotrophic state and lakes 

with naturally moderate nutrient levels in a mesotrophic state. Naturally eutrophic lakes are addressed 
3 

on a site-specific basis. A “lake” is defined, for purposes of interpreting the NNC in paragraph 62-

302.530(47)(b), F.A.C., as a lentic fresh waterbody with a relatively long water residence time and an 

open water area that is free from emergent vegetation under typical hydrologic and climatic conditions. 

Aquatic plants, as defined in subsection 62-340.200(1), F.A.C., may be present in the open water. Lakes 

do not include springs, wetlands, or streams (except portions of streams that exhibit lake-like 

characteristics, such as long water residence time, increased width, or predominance of biological taxa 

typically found in non-flowing conditions). Note that while lakes are typically characterized by a fringe 

of emergent vegetation, the presence of an open water area, where emergent vegetation is absent, 

distinguishes lakes from wetlands. Floating or submersed vegetation may be present in this open water 

area, and the system would still be defined as a lake, and numeric nutrient criteria would apply.

For lakes, the applicable numeric interpretations of the NNC in paragraph 62-302.530(47)(b), F.A.C., for 

chlorophyll a are shown in Table 1. The Department allows for an acceptable range of annual geometric 

means of TN and TP, up to the values shown in the “maximum calculated numeric interpretation” 

column, as long as the applicable chlorophyll a criterion is achieved in that same year. These numeric 

interpretations for TN, TP, and chlorophyll a cannot be exceeded more than once in any consecutive 

calendar three year period and apply statewide. 

Table 1. Lakes chlorophyll a, TN, and TP criteria. 

1 For lakes with color > 40 PCU in the West Central Nutrient Watershed Region, the maximum TP limit is 0.49 mg/L, 

which is the TP streams threshold for the region.
4 

If there are insufficient data to calculate the annual geometric mean chlorophyll a for a given year or the 

annual geometric mean chlorophyll a exceeds the values in Table 1 for the lake type, then the applicable 

numeric interpretations for TN and TP are the minimum values in the table. If there are sufficient data 

to calculate the annual geometric mean chlorophyll a and the mean does not exceed the chlorophyll a 

value for the lake type in Table 1, then the TN and TP numeric interpretations for that calendar year are 

the annual geometric means of ambient TN and TP samples for that lake, subject to the minimum and 

maximum TN and TP limits in the table. 

If a lake is influenced by an upstream NPDES discharger, the Water Quality Based Effluent Limitation 

(WQBEL) evaluation for that discharge would determine the specific TN and TP levels (again subject to 

the upper nutrient values for TN and TP) that would maintain the appropriate chlorophyll a target for 

the lake (6 or 20 μg/L) during all years, including years representing critical conditions. This evaluation 

would involve water quality modeling set to achieve a “never to exceed” chlorophyll target scenario. 

The Department evaluated the inter-annual variability in lake chlorophyll a levels and found that interannual standard deviation (natural log-transformed) typically ranges from 0.305 to 0.533. Given this 

level of variability, the long-term geometric chlorophyll a concentration in a colored or alkaline clear

lake would need to be between 12.8 and 15.5 μg/L to be consistently found in compliance with the 

chlorophyll a standard of 20 μg/L. Consequently, the numeric nutrient permit limits for a point source 

discharger that influences a downstream lake would need to be adjusted to ensure attainment of

chlorophyll a targets in this lower range during all years, with the precise permit limits being dependent

upon site specific factors. If this demonstration of attainment cannot be made, the discharger could 

pursue other options, which include effluent nutrient reductions, discharge re-location (e.g., land 

application), or a Site Specific Alternative Criterion (establish alternate chlorophyll and nutrient targets 

that are fully protective of designated uses). 

Note that for lakes with color > 40 PCU in the West Central Nutrient Watershed Region, the relationship 

between chlorophyll a and TP is sufficiently variable such that the maximum allowable TP based on the 

upper prediction interval would be higher than the TP nutrient threshold for streams. To ensure 

protection of downstream streams, the maximum TP limit was set at 0.49 mg/L, which is the TP streams 

threshold for the region.

Nitrate-Nitrite Criterion for Spring Vents

The spring vent nitrate-nitrite criterion is based on a strong stressor-response relationship between 

nitrate-nitrite and the presence of nuisance algal mats, with the criterion established at a concentration 

that would prevent nuisance mats from occurring (compared with natural background levels). A “spring 

vent” is defined as a location where groundwater flows out of a natural, discernible opening in the 

ground onto the land surface or into a predominantly fresh surface water.

For spring vents, the applicable numeric interpretation of the NNC in paragraph 62-302.530(47)(b), 

F.A.C., is 0.35 mg/L of nitrate-nitrite (NO3 + NO2) as an annual geometric mean, not to be exceeded 

more than once in any three consecutive calendar year period.
5 

Using Measures of Flora and Fauna and Regional Nutrient Thresholds 

in Streams

Despite an exhaustive effort to develop stressor-response relationships between nutrients and 

biological responses in streams, insufficient responses were observed to develop numeric nutrient 

criteria. Therefore, to assess whether a stream attains the NNC in paragraph 62-302.530(47)(b), F.A.C., 

pursuant to the provisions in paragraph 62-302.531(2)(c), F.A.C. , an evaluation of water chemistry, 

biological data (flora and fauna), and physical information is used to determine if a stream’s nutrient 

concentrations are protective of balanced flora and fauna. Because of the complexity associated with 

nutrient enrichment effects, no single assessment tool is adequate to evaluate all potential impacts, and 

instead, a weight-of-evidence evaluation must be conducted, as described in Section 2.7 of Sampling 

and Use of the Stream Condition Index (SCI) for Assessing Flowing Waters: A Primer (DEP-SAS-001/11), 

which was incorporated by reference in the rule. The final result allows a scenario in which the TN 

and/or TP thresholds are exceeded, but because the floral and faunal measures are met, the streams are 

found to be healthy and well balanced. In those occasions, the Department will provide information to 

the public on the TN and TP levels that would be associated with the well-balanced aquatic community.

STREAM DEFINITION

For purposes of interpreting the NNC in paragraph 62-302.530(47)(b), F.A.C., under paragraph 62-

302.531(2)(c), F.A.C., a “stream” is defined as a predominantly fresh surface waterbody with perennial 

flow in a defined channel with banks during typical climatic and hydrologic conditions for its region 

within the state. During periods of drought, portions of a stream channel may exhibit a dry bed, but 

wetted pools are typically still present during these conditions. Streams do not include: (a) nonperennial water segments where fluctuating hydrologic conditions, including periods of desiccation, 

typically result in the dominance of wetland and/or terrestrial taxa (and corresponding reduction in 

obligate fluvial or lotic taxa), wetlands, or portions of streams that exhibit lake characteristics (e.g., long 

water residence time, increased width, or predominance of biological taxa typically found in non-flowing 

conditions), or tidally influenced segments that fluctuate between predominantly marine and 

predominantly fresh waters during typical climatic and hydrologic conditions; or (b) ditches, canals and 

other conveyances, or segments of conveyances, that are man-made, or predominantly channelized or 

predominantly physically altered; and 1) are primarily used for water management purposes, such as 

flood protection, stormwater management, irrigation, or water supply; and 2) have marginal or poor 

stream habitat or habitat components, such as a lack of habitat or substrate that is biologically limited, 

because the conveyance has cross sections that are predominantly trapezoidal, has armored banks, or is 

maintained primarily for water conveyance.

This stream definition applies only to the numeric nutrient criteria for streams adopted at paragraph 62-

302.531(2)(c), F.A.C. (hereafter referred to as paragraph (2)(c)). The definition does not apply to any 

other water quality criteria adopted within Florida rules except those that specifically reference 

paragraph (2)(c). Rule 62-302.531(1), F.A.C., states that the NNC continues to apply for those waters 

without numeric nutrient criterion. 
6 

The stream definition in Rule 62-302.200(36), F.A.C., was carefully crafted to ensure consistency with 

the scientific procedures and methods used to establish the numeric nutrient standards expressed in 

paragraph (2)(c). Neither canals nor non-perennial streams were used in the derivation of the nutrient 

thresholds in paragraph (2)(c). Furthermore, the physical and hydrologic alterations within a canal would 

almost always result in the failure of the SCI component of the standards in paragraph (2)(c), regardless 

of nutrient levels. This limits the utility of the SCI for determining the affects of nutrients in canals. 

IMPLEMENTATION OF NNC IN STREAMS

To evaluate ecosystem health in streams, it is important to acknowledge that adverse nutrient 

enrichment effects follow a conceptual ecological model (Figure 2). When anthropogenic nutrient 

loading or concentrations exceed a system’s assimilative capacity, the primary response consists of 

changes to the primary producer communities (periphyton, phytoplankton, or vascular plants), and 

excess production of plant biomass. In turn, this enhanced floral biomass can lead to habitat loss (e.g., 

from excess periphyton smothering or nuisance plant biomass accumulation), food web alterations (e.g., 

dominance of taxa that thrive in nutrient/organic matter enriched conditions), and/or low dissolved 

oxygen (DO) from decomposition of plant biomass or respiration. This chain of events is ultimately 

reflected in meaningful biological endpoints, such as excessive algal mats, excess water column 

chlorophyll a, excess nuisance vascular plant growth, and/or failing Stream Condition Index (SCI) scores. 

These adverse biological endpoints constitute imbalances of aquatic flora and/or fauna. 

Conversely, if data show that biological health is fully supported in an aquatic system (no adverse 

responses consistent with the ecological model), one may conclude that the associated nutrient regime 

is inherently protective of the waterbody, and the NNC is achieved. 

For streams, if a site specific interpretation pursuant to paragraph 62-302.531(2)(a), F.A.C. (TMDL, SSAC, 

Level II WQBEL or RA Plan) has not been established, Nutrient Thresholds are used to interpret the NNC

in combination with biological information. The NNC in paragraph 62-302.530(47)(b), F.A.C., shall be 

interpreted as being achieved in a stream segment if: 

• Information on chlorophyll a levels, algal mats or blooms, nuisance macrophyte growth, 

and changes in algal species composition do not indicate an imbalance in flora or fauna; 

AND EITHER

• The average score of at least two temporally independent SCIs performed at 

representative locations and times is 40 or higher, with neither of the two most recent 

SCI scores less than 35 (i.e., no faunal imbalances), OR

• The Nutrient Thresholds (expressed as annual geometric means) in Table 2 are not 

exceeded more than once in a three year period (see Figure 3 for regions).
7 

Figure 2. Simplified nutrient enrichment conceptual model used to assess potential adverse effects of 

nutrients on aquatic life and human uses in streams. Relationships between nutrients and biological 

responses are highly influenced by site-specific and mitigating factors.

Table 2. Reference stream-based nutrient thresholds. 

Nutrient Region Total Phosphorus 

Threshold

Total Nitrogen 

Threshold

Panhandle West 0.06 mg/L 0.67 mg/L 

Panhandle East 0.18 mg/L 1.03 mg/L 

North Central 0.30 mg/L 1.87 mg/L 

Peninsula 0.12 mg/L 1.54 mg/L 

West Central 0.49 mg/L 1.65 mg/L 

South Florida No numeric nutrient threshold. The narrative 

criterion in paragraph 62-302.530(47)(b), 

F.A.C., applies.2

 

 

2 Chlorophyll a impairment thresholds in the IWR will continue to be used to assess South Florida flowing waters.
8 

Figure 3. Map of stream nutrient regions. 

FLORAL EVALUATION FOR DETERMINING ACHIEVEMENT OF NNC

During numeric nutrient criteria development, the Department, in coordination with EPA, conducted a 

series of comprehensive statistical analyses to identify relationships between human disturbance 

(including nutrient enrichment) and adverse floral responses (e.g., algal taxonomic composition, algal 

and vascular plant abundance, chlorophyll a, etc.) using an extensive data set collected in Florida 

streams. The relationships were statistically weak, and neither the Department nor EPA could identify 

floral health/impairment thresholds associated with human disturbance or nutrient 

concentrations/load. The Department will continue these investigations, and if a relationship is 

eventually found, then stream floral measures would be strong candidates for Biocriteria, similar to the 

Stream Condition Index and Lake Condition Index. Until these Biocriteria are developed, the 

Department’s approach is to determine whether the floral components at a given stream are consistent 

with the floral measures found within the EPA reference stream distribution (generally the 90th

percentile, as was used to develop the nutrient thresholds). If all floral measures are within the EPA 

reference site distribution, one may reasonably conclude the presence of a balanced floral community. 

Based on all potential floral outcomes associated with the conceptual model in Figure 2, the

Department evaluates the Rapid Periphyton Survey (RPS), community composition (autecological) 

information associated with dominant algal taxa, Linear Vegetation Survey (LVS), and chlorophyll a data

using a weight of evidence approach, as described below. These assessments were chosen because 

they:

• Represent the entire range of potential floral responses to nutrients, consistent with the 

nutrient enrichment conceptual model in Figure 2; 

• May routinely be conducted by Department staff, who have been extensively trained in 

the associated Standard Operating Procedures (SOPs); and
9 

• Comprise the most advanced floral assessment tools currently available for the State of 

Florida. 

In addition to comparing water quality data to the stream nutrient thresholds in Table 2 and evaluating 

available SCI data, the Department evaluates the floral components, described below, to determine if 

the stream exhibits balanced flora. Although a weight of evidence approach is used (generally using 

floral thresholds established at the 90th or 10th percentile of the EPA reference stream distribution, 

depending on the metric), if any one these floral measures indicates an imbalance, then the Department 

would conclude that the stream does not attain the NNC. Floral measures alone can provide evidence 

that the nutrient standard at Rule 62-302.531(2)(c) is not achieved, leading to the waterbody being 

placed on the Florida Verified List and Clean Water Act 303(d) list.

If floral data are unavailable for a stream that exceeds the Nutrient Thresholds, it is the Department’s 

intent to collect the information during the Watershed Management Assessment Cycle associated with 

the Impaired Waters Rule. If the necessary information is not collected during the assessment cycle 

(due to logistical considerations, etc.) and either the TN or TP thresholds are exceeded, the Department 

places such waters on the Study List, which is submitted to EPA as part of the 303(d) list of impaired 

waters, until conclusions can be made. 

To conduct a conclusive biological evaluation of the floral community, it is necessary to conduct two 

floral evaluations using the metrics described below to address the temporal persistence. One 

evaluation is not sufficient to document a stream’s long term floral health because natural climaterelated circumstances during any given time period can cause shifts in the vascular plant and algal 

communities. Collecting a temporally independent sample can further minimize Type 1 and Type 2 

error. 

When evaluating the floral evidentiary thresholds described below, comparisons to contemporaneous 

floral data from minimally disturbed reference streams (with minimal disturbance being based on the 

same criteria employed by EPA during nutrient threshold development) is an important component of 

the process. The expression of nutrient responses is very complex, and could be related to many 

natural factors, such as extended low flow periods (increased residence time), natural variation in grazer 

populations, changes in light penetration, and system morphology. For this reason, it is important to 

assess how floral metrics fluctuate at reference sites that are sampled under environmental and 

climatological conditions similar to any test site being evaluated. The RPS, LVS, algal species 

composition, and chlorophyll data from reference streams located proximally to any stream under 

evaluation should be considered as part of the evidentiary process. Algal evaluations are complex and 

should be considered with regard to all the variables described above; however, the Department has 

provided a decision key for each of the metrics to assist with decision making. 
10

EVALUATING ALGAL MATS

The RPS is used to quantify the extent (coverage) and abundance (thickness) of attached algae 

(periphyton) and is an effective tool to quantify abundance of nuisance or problematic algal growth. The 

Department compares RPS results from a stream to the RPS results compiled from the population of 

minimally disturbed and healthy sites that was sampled by the Department as part of NNC 

development. RPS rank 4-6 coverage (Rank 4-6 represent epiphyte lengths of > 6 mm) at Nutrient 

Benchmark streams ranged from 0% to 66%, with a mean value of 6% and a 90th percentile value of 25%. 

RPS rank 4-6 coverage at all biologically healthy sites (as indicated by Stream Condition Index scores > 

40), ranged from 0% to 91%, with a mean value of 8% and a 90th percentile value of 32%. Although 

these RPS distributions are fairly similar, the Department concluded that use of an RPS evidentiary 

threshold based on the 90th percentile of the EPA reference sites would be consistent with the manner 

in which the nutrient thresholds were derived. Therefore, if a stream exhibits a percent coverage for RPS 

ranks 4-6 of 25% or less in both samples, the RPS results indicate evidence of no imbalance of flora. If a 

stream segment exceeds an RPS 4-6 coverage of >25% during two consecutive, temporally independent 

samplings (> 3 months apart), the Department considers this as evidence that the NNC is not achieved. 

If the two samples have differing results in relation to the evidentiary threshold, then the preliminary 

analysis of this metric alone is inconclusive. Reviewing other data, information, or water quality/biology 

variables can help inform the reasons behind the differing results. Additional sampling should be 

conducted until two temporally independent samplings either attain, or do not attain, the evidentiary 

thresholds, so a final decision can be made. 

Where the RPS 4-6 coverage is greater than 20%, an evaluation of the algal species composition

(identifying the five most dominant taxa) is also conducted to provide additional information whether 

there is no imbalance of flora. Where RPS 4-6 coverage is <20%, there is no need to collect samples for 

algal species composition because the stream is clearly within the reference site distribution, and 

therefore, the algal species composition is presumed to be acceptable. 

RPS Decision Key

1. Were environmental conditions associated with the RPS samples representative of the typical 

conditions of the system? (e.g., flow between 10th and 90th percentile of long term discharge, 

light penetration characteristic of system, sampling location representative of waterbody 

segment, etc). 

1a. Yes, proceed to couplet 2.

1b. No. Collect additional RPS samples at representative locations and during representative 

conditions, and return to couplet 1.

2. Results of two temporally independent RPS samplings show that RPS rank 4-6 is 25% or less?

2a. Yes. Evidence that the waterbody achieves the algal mat component of floral measures

(other components must still be evaluated). If RPS rank 4-6 results are between 20% to 25%, 
11

then algal species composition will also be evaluated (see algal species composition decision 

key).

2b. No, evidence that the nutrient standard at 62-302.531(2)(c) is not achieved. 

EVALUATING CHANGES IN SPECIES COMPOSITION

Changes in algal species composition (through an analysis of autecological information) are also 

evaluated using the latest scientific references for algal species. The Department maintains a list of the 

scientific references used in this evaluation. While many references are for studies conducted in other 

States and other countries, they still provide valuable information concerning nutrient enrichment in 

Florida because many of the indicator algal species are distributed worldwide and have been shown to 

have consistent sensitivity to nutrients wherever found. 

Although the Department conducted a comprehensive study of stream periphyton in Florida in an 

attempt to formulate a multi-metric index for assessing human disturbance (including nutrient effects), 

the statewide data indicated that that the periphyton community composition was more highly 

correlated with pH (and conductivity) than to nutrients or measures of human disturbance. 

Additionally, common metrics that typically decrease in response to human disturbance in invertebrate 

communities, such as taxa richness and diversity, often increase in algal communities when comparing 

oligotrophic to eutrophic streams, meaning such metrics are not useful for assessing anthropogenic 

nutrient inputs. Given these constraints, the Department assesses the environmental information 

associated with dominant algal taxa qualitatively using the scientific literature to determine if they are 

indicative of nutrient enriched/imbalanced conditions. 

For example, nutrient enriched Florida springs are typically characterized by an abundance of one or 

more of the following taxa: Lyngbya wollei, Oscillatoria sp., Aphanothece sp., Phormidium sp., 

Vaucheria sp., Spirogyra sp., Cladophora sp., Rhizoclonium sp., Dichotomosiphon sp., Hydrodiction sp., 

Enteromorpha sp., and Chaetomorpha sp. Other algal indicators of nutrient enrichment from the 

literature include: Anabaena sp., Euglena sp., Chlamydomonas sp., Scenedesmus sp., Chlorella sp., 

Rhopalodia spp., Gomphonema spp., Cosmarium sp., Nitzschia spp., Navicula spp., and Stigeoclonium sp. 

Dominance of such taxa at a stream where the RPS rank 4-6 >20% would be evidence that the NNC is 

not achieved.

As another example of this approach, the Everglades TP criterion was largely based on observed shifts in 

the dominant algal taxa from those characteristic of reference conditions (e.g., Scytonema sp., 

Schizothrix sp.) to taxa indicative of nutrient enriched conditions (e.g., Gomphonema parvulum, Navicula 

minima, Nitzschia amphibia, Nitzschia palea, Oscillatoria sp., Rhopalodia gibba, Scenedesmus sp.,

Anabaena sp., Cosmarium sp., and Lyngbya wollei). 
12

Because a statewide analysis of algal community metrics (including the percentage of pollution sensitive 

and pollution tolerant taxa) failed to correlate well (r 2 < 0.1) with human disturbance, this evaluation of 

algal community composition in streams must be conducted on a site-specific basis, using the latest 

scientific references. During this assessment, the natural ionic regime (pH, conductivity) should be 

taken into account because past studies indicate that pH and conductivity significantly influence the 

algal community composition. Because of the variability associated with algal species composition, sitespecific responses are emphasized as part of the weight of evidence approach. Additional sampling 

should be conducted until two temporally independent samplings either attain, or do not attain, the 

evidentiary thresholds, so a final decision can be made. 

Algal Species Composition Decision Key

1. Were environmental conditions associated with the RPS samples and algal taxonomic collections 

representative of the typical conditions of the system? (e.g., flow between 10th and 90th

percentile of long term discharge, light penetration characteristic of system, sampling location 

representative of waterbody segment, etc.). 

1a. No. Collect additional RPS samples and algal taxonomic composition samples at 

representative locations and during representative conditions, and return to couplet 1. 

1b. If Yes, see couplet 2.

2. Results of two temporally independent RPS samplings show that RPS rank 4-6 is 20% or less?

2a. Yes. Evidence that the waterbody achieves the algal species composition component of

floral measures (other components must still be evaluated).

2b. If No, see couplet 3. 

3. Do dominant taxa3 of algal community include taxa known to be nutrient enrichment 

indicators? (see list above and references in Appendix). 

3 a. Yes. Evidence that the nutrient standard at Rule 62-302.531(2)(c) is not achieved. 

3b. No. This is evidence that the waterbody achieves the algal species composition component 

of floral measures (other components must still be evaluated). 

EVALUATING THE PRESENCE OR ABSENCE OF NUISANCE MACROPHYTE GROWTH

Another line of evidence to determine if streams are healthy is determining the relative lack of nuisance 

macrophyte growth by certain vascular plant taxa that may interfere with designated uses of a 

waterbody. The Linear Vegetation Survey (LVS) is a rapid assessment tool for evaluating the ecological 

condition of streams based on vascular plants. Because many streams naturally have very little or no 

vegetation, interpretation of LVS data requires that a minimum of two square meters (2 m2

) of 

 

3 The Department will evaluate those dominant species that individually constitute approximately 10% or more of 

the community.
13

macrophyte coverage be present throughout a 100 meter stream reach. If there is <2 m2 of vascular 

plant coverage present in a 100 m stream reach, there are no floral imbalances attributable to aquatic 

plants. LVS results from a stream are compared with LVS results compiled from the population of EPA 

reference streams sampled by the Department as part of NNC development. The Department evaluated 

LVS data from the EPA reference streams and found that if a site’s average C of C score is greater than or 

equal to 2.5 (the 10th percentile of the distribution), the plant community composition may be 

considered to be part of the reference site distribution. Based on the Department’s experience in 

minimally disturbed streams and the types of plants associated with C of C scores greater than or equal 

to 2.5, this threshold was determined to be reasonable and protective. 

The Department also analyzed the frequency of occurrence of Florida Exotic Plant Pest Council (FLEPPC)

exotics in the EPA reference streams, and found that, due to the influence of a few streams at the 90th

percentile, FLEPPC exotics made up approximately 40% of the total plant occurrences. Considering the 

somewhat limited number of reference streams with vascular plants (nineteen) and the variability in the 

data, the Department decided to set the FLEPPC threshold at the 80th percentile of the distribution. 

Therefore, if the frequency of occurrence of FLEPPC exotics at a site is less than or equal to 25% of the 

total plant occurrences (the 80th percentile of the distribution), the site may be considered to be part of 

the reference site distribution. 

Therefore, if a site’s average Coefficient of Conservatism (C of C) score is > 2.5 and the frequency of 

occurrence of FLEPPC exotic taxa is < 25% of the total plant occurrences in two independent samples, 

this would indicate no imbalance of flora. Because of the inherent temporal variability in aquatic plant 

communities, two temporally independent LVS assessments should be conducted. If a stream 

segment’s C of C score is < 2.5 and the frequency of occurrence of FLEPPC exotic taxa is > 25% during 

two consecutive, temporally independent samplings, the Department considers this as evidence that the 

NNC is not achieved. While variability of LVS sampling is typically low, if the two samples have differing 

results in relation to the evidentiary threshold, then the preliminary analysis of this metric alone is 

inconclusive. Reviewing other data, information, or water quality/biology variables can help inform the 

reasons behind the differing results. Additional sampling should be conducted until two temporally 

independent samplings either attain, or do not attain, the evidentiary thresholds, so a final decision can 

be made. 

LVS Decision Key

1. Were environmental conditions associated with the LVS samples representative of the typical 

conditions of the system (e.g., flow between 10th and 90th percentile of long term discharge, 

light penetration characteristic of system, sampling location representative of waterbody 

segment, etc.). 

1a. No. Collect additional LVS samples at representative locations and during representative 

conditions, and return to couplet 1.

1b. Yes, proceed to couplet 2.
14

2. Given that invasive exotic species can occur even in the absence of nutrient impacts and that 

aquatic plant management practices can also affect LVS results, is there evidence the LVS results 

can be linked to anthropogenic nutrient inputs? 

2a. Yes, proceed to couplet 3.

2b. No. The LVS results are inconclusive and other lines of floral evidence should be used.

3. Results of two temporally independent LVS samplings show that C of C score is > 2.5 and the 

frequency of occurrence of FLEPPC exotic taxa is < 25%? 

3a. Yes. Evidence that the waterbody achieves the nuisance macrophyte growth component of 

floral measures (other components must still be evaluated).

3b. No. Evidence that the nutrient standard at 62-302.531(2)(c) is not achieved. 

EVALUATING ALGAL BLOOMS, CHLOROPHYLL A, AND PHYTOPLANKTON TAXONOMIC DATA

An annual geometric mean chlorophyll value of >20 μg/L is used as an impairment threshold for both 

lakes and streams in Chapter 62-303, F.A.C. However, it is commonly understood that healthy lakes in 

Florida may be characterized by annual geometric mean chlorophylls up to 20 μg/L, while most healthy 

streams would be expected to have significantly lower chlorophyll a levels. While this impairment 

threshold for streams was supported by an expert panel of Florida scientists that helped the 

Department develop the Impaired Waters Rule (IWR), neither the expert panel nor a review of stream 

chlorophyll a literature was able to identify a stream chlorophyll a value below 20 μg/L that definitively 

did, or did not, support aquatic life uses. 

The range in “healthy” stream chlorophyll a values is due to a variety of site specific factors, such as 

system morphology, water residence time, and presence of lentic taxa may indicate a healthy aquatic 

stream in a natural transition from a lotic to lentic system during the time period studied. While the 

Department compares the chlorophyll a results from a stream to chlorophyll a results compiled from the

population of minimally disturbed and healthy sites that was sampled by the Department as part of NNC 

development, these site specific factors must also be taken into account. If a stream exhibits annual 

geometric mean chlorophyll a concentrations between the mean observed at these minimally disturbed 

and healthy sites (2.0-2.1 μg/L) and the associated 90th percentile values (3.2-3.5 μg/L), this is a clear 

indication of no imbalance of flora. However, some Nutrient Benchmark streams and biologically 

healthy streams also exhibit annual geometric mean chlorophyll a values up to 17 μg/L and 19 μg/L, 

respectively. Because the remaining distribution of observed annual geometric mean chlorophyll a

values includes values approaching the IWR impairment threshold (and higher percentiles of the 

distribution actually exceeded it), the Department chose to continue to utilize 20 μg/L as a chlorophyll 

impairment threshold. Therefore, streams with annual average chlorophyll values between 3.2 μg/L and 

20 μg/L are evaluated on a site specific basis, and factors such as water residence time, flow, color, 

climatological conditions, and size of the stream/river (i.e., stream order) are considered when 

chlorophyll a values are within this range. If a site has chlorophyll values within the 3.2 μg/L to 20 μg/L 

range, the assessment is inconclusive until the Department documents a decision regarding whether 

chlorophyll a conditions reflect and imbalance in flora or not. When the Department determines that 
15

the values indicate enrichment (e.g., are higher than functionally similar reference streams in the 

region), the Department considers this evidence of imbalances in flora, and vise versa. 

The Department also assesses trends in chlorophyll a using a temporal trend test (a Mann’s one-sided, 

upper-tail test for trend, with a 95% confidence interval) in conjunction with the chlorophyll a

impairment threshold. The observation of a statistically significant increase in chlorophyll a in a stream 

is another line of evidence used by the Department to determine floral imbalances.

The Department also uses the presence of phytoplankton blooms as an indicator of floral imbalances. 

An unacceptable phytoplankton bloom would consist of a situation where an algal species, whose 

noxious characteristics or presence in sufficient number, biomass, or areal extent, may reasonably be 

expected to prevent, or unreasonably interfere with, the designated use of a waterbody. The 

Department evaluates the autecological information for the dominant bloom species, in conjunction 

with the associated chlorophyll a when assessing imbalances of flora. 

Chlorophyll/Algal Bloom Decision Key

1. Were environmental conditions associated with the chlorophyll samples representative of 

typical conditions for the system? (e.g., flow between 10th and 90th percentile of long term 

discharge, light penetration characteristic of system, sampling location representative of 

waterbody segment, etc.). 

1a. No. Collect additional chlorophyll samples at representative locations and during 

representative conditions, and return to couplet 1.

1b. If Yes, see couplet 2.

2. Annual geometric mean chlorophyll < 3.2 ug/L?

2a. Yes. Evidence that the waterbody achieves the chlorophyll a/algal bloom component of 

floral measures (other components must still be evaluated).

2b. If No, see couplet 3.

3. Annual geometric mean chlorophyll >20 ug/L more than once in a three year period?

3a. Yes. The narrative nutrient standard at 62-302.531(2)(c) is not achieved. 

3b. No, annual geometric mean chlorophyll is between 3.2 and 20 ug/L, see couplet 4. 

4. After considering site specific factors that affect chlorophyll concentrations, such as system 

morphology, water residence time, or consistency with other functionally similar reference sites, 

can it be documented that the chlorophyll a values represent a healthy well balanced 

phytoplankton community? 

4a. Yes. Evidence that the waterbody achieves the chlorophyll a/algal bloom component of 

floral measures.

4b. No. 

Evidence that the nutrient standard at 62-302.531(2)(c) is not achieved.
16

4c. Inconclusive because of insufficient contemporaneous data from other functionally similar 

reference sites. Waterbody will be placed on the Study List if either of the TN or TP 

thresholds were exceeded. 

FLORAL MEASURES SUMMARY

As described above, the Department derived the floral thresholds that are used for this “weight of 

evidence evaluation” using a distribution of a population of minimally disturbed Benchmark streams

(the same streams used by EPA for their criteria development). The thresholds summarized in Table 3

can be used when developing evidence supporting a Department conclusion regarding the balance of 

the floral community. If all floral measures are achieved, a stream meets the floral component of a 

healthy, well balanced aquatic system, because it is within the minimally disturbed Benchmark stream 

condition. However, if any one these floral measures indicates an imbalance, then the stream does not 

attain the NNC. Examples of this application of scientific reasoning are provided below. 

Table 3. Floral measures summary. These values were based on the distribution of a population of 

minimally disturbed Benchmark sites sampled by the Department as part of Numeric Nutrient Criteria 

development (the same benchmark sites EPA used for their criteria). 

Floral Metric

Evidentiary Threshold of No 

Imbalances

LVS C of C Site average > 2.5

LVS FLEPPC Site average < 25%

RPS

< 25% rank 4-6 coverage

20 to 25 % rank 4-6 coverage, 

evaluate algal autoecological data

Chlorophyll < 20 ug/L; 3.2 to 20 ug/L = site 

specific

Algal Community Composition 

(Autecology) No adverse shifts in dominant taxa

FAUNAL EVALUATION FOR DETERMINING ACHIEVEMENT OF NNC

Paragraph (2)(c) requires a demonstration that a stream has well-balanced populations of flora and 

either attains the Nutrient Thresholds or has healthy, well balanced fauna. The presence of healthy 

fauna can be shown through the Stream Condition Index (SCI). 

The SCI is a biological assessment procedure that measures the degree to which flowing fresh waters 

support a healthy, well-balanced biological community, as indicated by benthic macroinvertebrates. The 

Department and EPA have concluded that a balanced faunal community is achieved if the average score 

of at least two temporally independent SCIs, performed at representative locations and times, is 40 or 
17

higher, with neither of the two most recent SCI scores less than 35. To qualify as temporally 

independent samples, each SCI must be conducted at least three months apart. SCIs collected at the 

same location less than three months apart will be considered one sample, with the mean value used to 

represent the sampling period. 

Attainment of the SCI threshold is an indication that the faunal community of the stream is not being 

adversely affected by nutrients to the extent that there is a loss in designated use. However, failure of 

the SCI does not necessarily mean that the stressor causing the loss of designated use is nutrients. 

Evaluation of other factors, as indicated by the nutrient enrichment model in Figure 2 (including nutrient 

concentrations and floral communities) is useful information that could indicate nutrients are a factor. 

While the stressor may not be known, a failed SCI does indicate that fauna is not well-balanced.

Alternatively, if the benchmark Nutrient Thresholds in the Table in paragraph (2)(c) are attained, then 

the faunal community of the stream is presumed healthy with respect to nutrients, because the 

benchmark thresholds were derived using nutrient levels in high quality, minimally disturbed streams. 

However, regardless of attainment of benchmark thresholds, if SCI results are available and a stressor 

identification study demonstrate that the faunal community is not healthy as a result of nutrients, then 

the stream will be listed as impaired for nutrients. 

In summary, where the Nutrient Thresholds are exceeded but there are no imbalances in either aquatic 

flora (phytoplankton, periphyton, or vascular plants) or fauna (invertebrate community), the NNC is 

achieved. 

EXAMPLES OF A WEIGHT-OF-EVIDENCE APPROACH FOR DETERMINING ACHIEVEMENT OF 

NUTRIENT CRITERIA 

To evaluate whether a stream achieves the NNC, the investigator must compile water chemistry data 

(e.g., Total Nitrogen [TN], Total Phosphorus [TP], chlorophyll a, and ancillary parameters such as color, 

turbidity, DO, pH, conductivity, and temperature, nitrate, etc.) and a minimum of two samples of each of 

the following: RPS, LVS, HA, and SCI. Taken together, these data are used as multiple lines of evidence 

to decide whether a stream is healthy, with acceptable levels of nutrients. Supporting parameters, such 

as color and nitrate, are used to help determine nutrient sources (e.g., high colored swamps have 

naturally elevated TN; very clear groundwater-fed systems may have elevated nitrate). Examples of 

how the Department evaluates these multiple lines of evidence are provided in Table 4 and discussed 

below.

In Stream 1, although the RPS data showed a pulse of periphyton (which consisted of the generally nonproblematic alga, Oedogonium), it was not persistent, meaning the RPS results were acceptable. 

Because no plants were found in the water, the LVS results indicated no imbalances. However, an 

increasing trend was observed in annual chlorophyll a (using a Mann’s one-sided, upper-tail test for 

trend, with a 95% confidence interval), and the chlorophyll values exceeded those typically observed in 

healthy streams. Although the SCI score was currently acceptable and habitat was not limiting, the 

Department concluded that the chlorophyll issue, following the conceptual model in Figure 2, was 

sufficient to judge that this stream has impaired flora. It is likely that the increased organic matter 
18

enrichment associated with the excess phytoplankton (as indicated by the chlorophyll) would eventually 

lead to faunal imbalances.

Stream 2 was characterized by significant algal smothering, as demonstrated through the RPS results. 

Taxonomic identification showed the algae community to be dominated by Lyngbya, a known nuisance 

species. Although the vascular plant community, as assessed using the LVS, was within the range of

reference streams, and chlorophyll a was non-problematic, the algal growth resulted in aquatic habitat 

smothering (a component of the HA), which likely led to the failing SCI score. The Department

concluded that the RPS results, coupled with a poor habitat smothering score, was evidence that stream 

2 has impaired flora, which in turn caused impaired fauna. These responses are consistent with the 

nutrient enrichment model.

Although periphyton and chlorophyll a were not issues in stream 3, the HA and LVS results showed that 

the invasive exotic vascular plant, Hydrilla, was excessively abundant, leading to imbalances of flora. An 

increase in Hydrilla abundance was associated with reduced substrate diversity and failing SCI scores, 

meaning the elevated nutrient levels were associated with imbalances in flora and fauna, consistent 

with the nutrient enrichment model. This situation is complicated because invasive exotic plants can be 

observed even without nutrient enrichment. It is important to review other information, including the 

levels of nutrients in the waterbody that could contribute to species proliferation. In this circumstance, 

the Department concluded that excess anthropogenic nutrients exacerbated the floral community 

imbalances as evidenced by the LVS results.

Stream 4 is a minimally disturbed Benchmark stream with TN and TP levels at the upper 98th percentile 

of the data distribution used to establish the regional Nutrient Threshold. The RPS and SCI indicated 

normal, healthy conditions. No plants were observed in the water, meaning the LVS was acceptable. 

However, an annual chlorophyll a value of 10.5 μg/L was observed in one year, which is between the 3.5 

to 20 μg/L range, and site specific information was subsequently evaluated. In this case, a drought year 

was associated with the moderately elevated chlorophyll, and other nearby reference streams also 

exhibited similar increases in chlorophyll. The algae associated with the elevated chlorophyll included 

the diatoms, Achnanthes exiguum, Anomoeneis vitrea, and Cymbella minuta, which are normally found 

in reference streams. The Department concluded that the drought conditions were associated with the 

chlorophyll value, and that this level was within the variability of the reference site data. Because the 

SCI was healthy and there were no other indicators of nutrient issues, the Department concluded that 

nutrient levels associated with Stream 4 are acceptable and the NNC is achieved.
19

Table 4. Examples of RPS, LVS, chlorophyll a, HA, and SCI data used to illustrate a multiple lines-ofevidence approach used by the Department for determining whether or not a stream exhibits 

imbalances of flora or fauna. In these examples, TP, TN, or both nutrients exceed the regional Nutrient 

Threshold values. 

Measure Sample 

# 

Stream1

1 2 3 4 5 6

RPS (% Rank 4-6)

1 21 45 4 8 3 26

2 2 65 7 15 0 37

LVS

Avg. C 

of C

1 

No 

vegetation

2.6 1.9

No 

vegetation

3.5 1.8

2 

No 

vegetation

3.2 0.5

No 

vegetation

4.2 2.4

FLEPPC %

1 

No 

vegetation

12 45

No 

vegetation

0 31

2 

No 

vegetation

4 74

No 

vegetation

0 26

Chlorophyll (μg/L 

as annual 

geometric mean)

Year 1 17.2 1.1

NonDetect

10.5 3.5 1.3

Year 2 22.1 2.1

NonDetect

1.2 4.1 1.1

Increasing 

Chlorophyll Trend

Yes No No No No No

Habitat 

Assessment

1 121 109 105 133 81 110

2 113 102 98 126 77 107

SCI

1 45 44 39 67 22 42

2 39 33 29 58 31 39

1 In these examples, TP, TN, or both nutrients exceed the regional Nutrient Threshold values. No vegetation = No 

plants in water, therefore, LVS results indicate no imbalance.
20

Floral measures at stream 5 were non-problematic, despite nutrient concentrations that exceeded the 

regional threshold values. No primary or secondary nutrient responses, as described by the nutrient 

enrichment model, were observed, but the SCI indicated impaired fauna. The SCI results, combined with 

higher levels of nutrients, lead to the conclusion that the NNC is not achieved. In this case however, 

habitat assessment results indicated artificial channelization, poor substrate diversity and availability, 

and a compromised riparian buffer zone. Observations also indicated extensive hydrologic 

modifications in the drainage basin. These habitat and hydrologic factors were evaluated as part of a 

TMDL process, prior to initiating a TMDL. After an evaluation of all stressors (through a stressor 

identification study), habitat and hydrologic improvements were found to be the stressors affecting 

stream health, and not nutrient concentrations. The Department would then evaluate this stream 

under a site specific structure described in Rule 62-302.531, F.A.C.

In stream 6, both the RPS and LVS results suggested early warnings of nutrient enrichment, with 

persistent periphyton coverage and changes in the vascular plant community, even though chlorophyll a

and SCI results were acceptable. The periphyton community was dominated by Vaucheria, a known 

nuisance species, while the vascular plants, Alternanthera philoxeroides and Panicum repens (two 

FLEPPC exotics), were moderately abundant. Habitat assessment results indicated moderate 

smothering by the periphyton and a reduction in substrate diversity associated with the exotic plant 

growth. The Department concluded that this was sufficient evidence of floral imbalances, which if 

allowed to continue without intervention, would also result in faunal imbalances, as predicted by the 

nutrient enrichment model. 

STREAM SAMPLING LOCATIONS AND OTHER ENVIRONMENTAL CONSIDERATIONS

When conducting nutrient studies, it is important to confirm that sampling locations and other 

environmental conditions (canopy cover, habitat, water depth and flow, etc.) are representative of the 

system and that water quality data are collected in the same homogeneous waterbody segment as the 

biological monitoring stations. Establishing spatial relationships between the water quality data and 

biological health data is dependent upon the homogeneity of the stream or stream segment. In stream 

segments that have homogeneous nutrient concentrations, at least one biological station (for floral and 

faunal measures) should be sampled during two temporally independent time periods. If a stream is not 

homogeneous with regard to nutrients, the stream should be divided into homogeneous units 

(segments), and the biological evaluation conducted for each segment. 

The following elements should be addressed when sampling to evaluate attainment of the NNC in 

paragraph 62-302.530(47)(b), F.A.C., and to affirmatively demonstrate that nutrients are not adversely 

affecting flora and fauna:

1. Biological sampling locations should be selected to reduce or eliminate the effects of 

confounding variables. Sampling should be conducted in areas where other physical factors, 

especially habitat and hydrology, do not limit biological expectations. Efforts should be taken to 

establish sites in stream reaches (where possible) with minimal hydrological modifications and 

optimal habitat, including adequate substrate diversity and availability, intact stream 
21

morphology (minimal or no artificial channelization), adequate velocity and flow, and optimal 

riparian buffer zones (see the Department’s SOP FS 3000 for Habitat Assessment procedures). 

Sites should also be selected where light penetration through the tree canopy is representative 

of the stream segment (i.e., avoid bridge or powerline crossings where the canopy has been 

artificially changed in a relatively small area). While care should be taken to minimize 

confounding factors, sampling locations should be sited within stream segments that are 

representative of typical conditions. Additional information on controlling for the effects of 

confounding factors is presented in the SCI Primer. 

2. All biological sampling should be conducted consistent with the Department’s Standard 

Operating Procedures (SOPs) and SCI Primer. 

3. Water quality stations should be located where there is a clear relationship between the 

nutrient regime and the system’s biological health, as assessed using either the floral or faunal 

measures. For streams, this means that site-specific information should be relied upon to 

ensure that the biological sampling site(s) provide response information representative of 

potential effects caused by nutrients in the system. Therefore, site-specific confounding factors 

and the potential for downstream expression of nutrients should be considered when 

determining sampling locations. For example, if a discharge or tributary significantly influences 

the nutrient concentrations in an area associated with the biological collection site, then data 

from stations located upstream of that discharge should not be used for establishing the 

ambient values associated with the biological data. 

4. Unless a very large data set has been established, sampling during extreme climatic or 

hydrologic conditions, such as floods, droughts, or hurricanes, should be avoided. 

Nutrient Criteria in Estuaries

Rule 62-302.532, F.A.C., contains estuary-specific numeric interpretations of the NNC in paragraph 62-

302.530(47)(b), F.A.C., for estuaries along the Southwest Coast (roughly from Tampa Bay to Miami and 

the Florida Keys). These criteria were developed individually for each estuary segment to protect 

recreation and a healthy, well-balanced population of fish and wildlife, and are hierarchy 1 

interpretations pursuant to paragraph 62-302.531(2)(a), F.A.C. The concentration-based estuary 

interpretations are open water, area-wide averages. 

Decision Matrix and Examples for Implementing the 

Hierarchical Process

The Department has developed a decision matrix for assessing the stream nutrient thresholds in Rule 

62-302.531(2)(c), F.A.C. (Table 5) and examples that illustrate how Florida’s numeric nutrient criteria are 
22

assessed using the hierarchical framework. For both the matrix and the examples, the following 

assessment categories4

, were used: 

• 1 - Attaining all designated uses;

• 2 - Attaining some designated uses and insufficient or no information or data are present to 

determine if remaining uses are attained;

• 3A - No data and information are present to determine if any designated use is attained;

• 3B- Some data and information are present but not enough to determine if any designated use 

is attained;

• 3C - Potentially impaired, exceedances meet the requirements of the Impaired Waters Rule for 

placement on the Planning List;

• 4A - TMDL developed, additional sampling would be used to gauge success of TMDL;

• 4B - Impaired but TMDL not needed (Reasonable Assurance activities underway);

• 4C - Fails criteria but due to natural condition. In this case, the generic criteria are 

inappropriate, and development of a “natural background” (Type I) SSAC may be warranted;

• 4D - Fails criteria but causative pollutant has not been determined, therefore, a pollutant causeeffect study is needed;

• 4E - Impaired, but restoration ongoing; and 

• 5 - Impaired. Fails criteria and causative pollutant identified.

 

4 The assessment categories are the same as those in the Department’s Integrated Report. 
23

Table 5. Decision matrix for assessment of stream nutrient thresholds in Rule 62-302.531(2)(c), F.A.C. Reasonable Assurance is demonstrated for near-field 

effects when the receiving streams is shown to “Attain .531(2)(c)”. This table does not address increasing trends in nutrient concentrations, and increasing 

trends in nutrient causal or response variables can result in placement of waterbodies on the Study List or Verified List [303(d) List] independent of the 

conclusion articulated in this table. Assessing Stream Biological Health using the SCI pursuant to the biological health assessment provisions of the IWR is 

conducted concurrently to the Nutrient Assessments described in this table as follows: If only 1 SCI is available and it is <35, the water is placed on the

Planning List, Cat. 3c for biology; If only 1 SCI is available and it is >35, the water is placed in Cat. 3b for biology; If the 2 most recent SCIs have 1 sample <35 or 

the average is <40, the water is placed on the Study List, Cat. 4d for biology to conduct a Stressor Identification (SI) study to determine causative pollutant(s). 

If the SI study determines a pollutant is responsible for the biological impairment, the water is placed on the Verified List, Cat. 5. If the SI study determines 

nutrients are responsible (even if nutrient thresholds are attained), then 62-302.531(2)(c) is Not Attained, and the water is placed on the Verified List, Cat. 5. 

If the 2 most recent SCIs average 40 or higher, and neither is <35, then the water is placed in Cat. 2.

Attains Nutrient Thresholds for Both TN and TP

(3 Years of Data)

Nutrient Threshold Attainment Inconclusive for Either 

TN or TP

(< 3 Years of Data)

At Least One Nutrient Threshold Not Attained

(3 Years of Data)

SCI Attains

(2 Samples)

SCI 

Inconclusive

(<2 Samples)

SCI Not 

Attained

(1 or 2 

Samples)

SCI Attains SCI 

Inconclusive SCI Not Attained SCI Attains SCI Inconclusive SCI Not Attained

Attains 

Floral 

Measures

(2 Sampling 

Events)

Attains 

.531(2)(c)

Cat. 2

Attains 

.531(2)(c)

Cat. 2

Attains 

.531(2)(c)

Cat. 2

Attains 

.531(2)(c)

Cat. 2

Cannot 

Conclude 

.531(2)(c) 

Assessment

Cat. 3b

Cannot Conclude 

.531(2)(c) 

Assessment

Cat. 3b

Attains .531(2)(c)

Cat. 2

Cannot Conclude 

.531(2)(c) 

Assessment

Cat. 4d (Study & 

303(d) List)

.531(2)(c) Not 

Attained

Cat. 5 (Verified & 

303(d) List)

Floral 

Measures

Inconclusive

(<2 Sampling 

Events)

Cannot 

Conclude 

.531(2)(c) 

Assessment

Cat. 3b or 

3c(Planning 

List)

Cannot 

Conclude 

.531(2)(c) 

Assessment

Cat. 3b or 

3c(Planning 

List)

Cannot 

Conclude 

.531(2)(c) 

Assessment

Cat. 3b or 

3c(Planning 

List)

Cannot 

Conclude .53

1(2)(c) 

Assessment

Cat. 3b or 

3c(Planning 

List)

Cannot 

Conclude 

.531(2)(c) 

Assessment

Cat. 3b or 

3c(Planning 

List)

Cannot Conclude 

.531(2)(c) 

Assessment 

Cat. 4d (Study & 

303(d) List)

Cannot 

Conclude- 

.531(2)(c) 

Assessment

Cat. 4d (Study & 

303(d) List)

Cannot Conclude 

.531(2)(c) 

Assessment

Cat. 4d (Study & 

303(d) List)

.531(2)(c) Not 

Attained

Cat. 5 (Verified & 

303(d) List)

Any One 

Floral 

Measure Not 

Attained

(2 Sampling 

Events)

.531(2)(c) Not 

Attained

Cat. 5 (Verified 

& 303(d) List)

.531(2)(c) Not 

Attained

Cat. 5 

(Verified & 

303(d) List)

.531(2)(c) Not 

Attained

Cat 5 (Verified 

& 303(d) List)

.531(2)(c) Not 

Attained

Cat. 5 (Verified 

& 303(d) List)

.531(2)(c) Not 

Attained

Cat/ 5 (Verified 

& 303(d) List)

.531(2)(c) Not 

Attained

Cat. 5 (Verified & 

303(d) List)

.531(2)(c) Not 

Attained

Cat. 5 (Verified & 

303(d) List)

.531(2)(c) Not 

Attained

Cat. 5 (Verified & 

303(d) List)

.531(2)(c) Not 

Attained

Cat. 5 (Verified & 

303(d) List)
24

Hierarchies 1 and 2

EXAMPLES OF HIERARCHY 1 

Hierarchy 1 – TMDLs, nutrient SSACs, Level II WQBELs and other Department approved actions such as 

RA plans are the applicable numeric interpretation of the narrative nutrient criteria, subject to EPA 

review. 

• Freshwater Portions of the Lower St. Johns River 

o Status: Has a nutrient TMDL for TN and TP. 

o Action required: Assessed as category 4a. No additional action required. Implement 

TMDL and BMAP as planned.

• Marine Portion of the Lower St. Johns River

o Status: Has a TMDL for TN.

o Action required: Assessed as category 4a. Implement TN TMDL and BMAP as planned. 

Continue to implement the narrative for TP until applicable NNC adopted.

EXAMPLES OF HIERARCHY 2 

Hierarchy 2 – Numeric interpretation of the narrative criterion based on an established, quantifiable 

understanding of the stressor-response relationship between nutrient concentrations and biological 

imbalance. Currently this relationship has been determined only for freshwater springs and lakes.

• Lithia Springs

o Status: Has no site specific interpretation, but exceeds the springs-specific stressorresponse based nitrate criterion of 0.35 mg/L. 

o Action required: List the spring as Verified Impaired (category 5) and take action to 

achieve the 0.35 mg/L nitrate criterion. A Basin Management Action Plan (BMAP) will 

be developed that addresses sources of nitrogen in the springshed.

• Silver Springs

o Status: Has no site specific interpretation, but exceeds the springs-specific stressorresponse based nitrate criterion of 0.35 mg/L. 

o Action required: List the spring as Verified Impaired (category 5) and take action to 

achieve the 0.35 mg/L limit as nutrient criterion. Silver Springs has a TMDL scheduled 

to be complete in 2012, which will move it to Hierarchy 1. A BMAP will be developed 

that addresses sources of nitrogen in the springshed.
25

• Lake Harney

o Status: Has no site specific interpretation. Meets the lakes nutrient and chlorophyll a

criteria and Lake Vegetation Index results indicate a healthy plant community. 

o Action required: Not impaired (category 2), and no additional action required. 

• Lake Gibson 

o Status: Has no site specific interpretation. Meets the lakes chlorophyll a criteria, but 

exceeds the upper range of the TP criterion. 

o Action required: List the lake as Verified Impaired (category 5) and develop nutrient 

TMDL, which will serve as primary site specific nutrient interpretation. May also be a 

candidate for a SSAC since the chlorophyll a criteria is met (provided vascular plant 

community, as measured by the LVI, is also healthy). 

• Lake Istokpoga 

o Status: Has no site specific interpretation. Exceeds the lakes chlorophyll a criterion

more than once in a three year period. 

o Action required: Place on Verified List (category 5) for nutrient impairment and develop 

nutrient TMDL, which will serve as primary site specific nutrient interpretation. 

Hierarchy 3

Hierarchy 3 – As described in Table 5, the numeric interpretation of the narrative criterion is based on a 

combination of reference-based nutrient thresholds and biological information (currently limited to 

streams, excluding intermittent systems, canals/ditches, and South Florida region)

5

. Streams can fall 

into the following main categories at the end of the Phase 2 assessment of the Watershed Management 

Cycle: 

a. Waters that meet the nutrient thresholds and have sufficient data to document they have 

healthy flora. These waters are deemed to attain the NNC (category 2). 

b. Waters that exceed the nutrient thresholds, but are biologically healthy (both flora and fauna). 

These waters are deemed to attain the NNC (category 2). 

c. Waters that exceed the nutrient thresholds, but there is insufficient information to fully assess 

the biological health of the stream. These waters are placed on the Study List (category 4d). 

 

5 Streams are also independently assessed using the nutrient impairment thresholds in the IWR (20 ug/L 

chlorophyll a, for example).
26

d. Waters that meet the nutrient thresholds, but there is insufficient information to assess the 

floral community. These waters will be placed on the Planning List for additional study (category 

3c). 

e. Waters that meet the nutrient thresholds, but are not biologically healthy. These waters will be 

placed on the Study List to determine the causative pollutant (category 4d). If the causative 

pollutant is determined to be a nutrient, the waterbody will be listed on the Verified List 

(category 5) for nutrient impairment even if the nutrient thresholds are attained. 

f. Waters that exhibit an imbalance of flora, or exceed the nutrient thresholds and are not 

biologically healthy (fauna). These waters are placed on the Verified List (category 5). 

For category “f” waters above where nutrients are identified to be a causative pollutant, the 

Department will develop a site specific response (such as a TMDL), at which point the waterbody would 

fall under “Hierarchy 1” after formal Department action (with subsequent EPA approval). 

EXAMPLES OF HIERARCHY 3 

 Waters achieving the nutrient thresholds that are also biologically healthy.

• Little Manatee River

o Status: Has no primary site specific interpretation, but satisfies reference-based nutrient 

thresholds and is determined to have healthy biology (both flora and fauna). 

o Action required: No additional action required. Place assessed condition in category 2 

of the Integrated Report. 

 Waters that exceed the nutrient thresholds, but are biologically healthy. 

• Econfina River

o Status: Has no primary site specific interpretation. Exceeds reference-based nutrient 

thresholds due to natural swamp inputs, but has sufficient floral and faunal information 

to determine that it is biologically healthy. 

o Action required: Achieves NNC. No additional action required. Place assessed condition

in category 2 of the integrated report. 

• Aucilla River

o Status: Has no primary site specific interpretation. Exceeds reference-based nutrient 

thresholds due to natural swamp inputs, has evidence of healthy fauna (SCI), but 

requires further study to gather additional required floral information. 

o Action required: Place on Study List to gather sufficient floral data to make final 

determination. Place in Category 4d.
27

 Waters that meet the nutrient thresholds, but are not biologically healthy based on either failing 

SCIs or floral measures. Waters with failing SCIs are placed on the Study List to identify 

stressor/causative factor(s), or are placed directly on the Verified List if stressor/causative 

information is available. Waters with evidence of imbalance based on floral measures are placed 

directly on the Verified List.

• Weeki Wachee River

o Status: Has no primary site specific interpretation. Achieves reference-based nutrient 

thresholds, but is determined not to be biologically healthy due to failing SCI and excess 

algal mats. 

o Action required: Because floral information is available, bypass Study List and place on 

Verified List for nutrient impairment (due to excess algal mats) and develop nutrient 

TMDL, which can serve as primary and independent site specific nutrient interpretation. 

The Department will provide documentation for the record to demonstrate how the 

biological data indicate an imbalance in flora and/or fauna. Place assessed condition in 

category 5 of the Integrated Report.

• Huckleberry Creek

o Status: Has no primary site specific interpretation. Achieves reference-based nutrient 

thresholds, but is determined not to be biologically healthy due to excess nuisance plant 

growth.

o Action required: Because floral information is available, bypass Study List and place on 

Verified List for nutrient impairment (due to excess nuisance plant growth) and develop 

nutrient TMDL, which will serve as primary site specific nutrient interpretation. The 

Department will provide documentation for the record to demonstrate how the 

biological data indicate an imbalance in flora and/or fauna. Place assessed condition in 

category 5 of the Integrated Report.

 Waters that meet the nutrient thresholds, but do not have biological data (floral measures). 

• Halls Branch

o Status: Has no primary site specific interpretation. Achieves reference-based nutrient 

thresholds, but no biological data are available.

o Action required: Place on Planning List to gather sufficient floral data to make final 

determination. Place in Category 3b.

 Waters that exceed the nutrient thresholds and are not biologically healthy.

• New River

o Status: Has no primary site specific interpretation. Exceeds reference-based total 

phosphorus threshold and is not biologically healthy based on most recent SCI results. 
28

Action required: Place on Verified List for nutrient impairment and develop nutrient 

TMDL, which will serve as primary site specific nutrient interpretation. The water could 

be delisted for nutrients if a Stressor Identification Study determines that factors other 

than nutrients are responsible for the degradation. Place assessed condition in category 

5 of the Integrated Report.

Waterbody Types and Cases with Insufficient Information

In types of aquatic systems where the Department does not have sufficient information to 

accurately develop generally applicable NNC, such as Class III wetlands. The Department will 

continue to rely on existing assessment provisions contained in the Impaired Waters Rule to list 

these waterbodies. The Department will numerically interpret the narrative criterion as the 

information is developed. 

Other Components of NNC

• Attainment of the narrative criterion is assessed over a spatial area consistent with its 

derivation. For Tier 1 numeric interpretations based on paragraph 62-302.531(2)(a), 

F.A.C., the spatial application of the numeric interpretation is as defined in the 

associated order or rule. For lakes, the numeric interpretation shall be applied as a lakewide or lake segment-wide average. Except for extremely large lakes (e.g., Lake 

Okeechobee, which has been subdivided), the lakes criteria apply to lakewide averages. 

For spring vents, the numeric interpretation shall be applied in the surface water at or 

above the spring vent. For streams, the spatial application of the numeric 

interpretation shall be determined by relative stream homogeneity and shall be applied 

to waterbody segments or aggregations of segments as determined by the site-specific 

considerations. The stream nutrient thresholds were derived though a distributional 

analysis of data from homogeneous reference stream segments, with the spatial extent 

of each stream segment typically measuring approximately five linear miles. Two or 

more stream segments may be combined if the nutrient data are homogeneous, which 

is evaluated through routine statistical tests, such as Analysis of Variance or Student’s ttest, and if the results show that the segments are not significantly different at the 90 

percent confidence level. Data will be transformed (e.g., log) prior to statistical analysis 

if the data are not normally distributed.

• Except for data used to establish historic chlorophyll a levels, chlorophyll a data shall be 

measured according to the Department document titled “Applicability of Chlorophyll a 

Methods” (DEP-SAS-002/10), and be corrected for, or free from, the interference of 

phaeophytin.

• If there is more than one hierarchy 1 interpretation for a given waterbody, the most 

recently adopted interpretation controls. 
29

NNC and Protection of Downstream Waters

Protection of downstream waters is required in the new nutrient standards by the statement, “The 

loading of nutrients from a waterbody shall be limited as necessary to provide for the attainment and 

maintenance of water quality standards in downstream waters.” This provision is implemented by the 

Department by:

• Using models to allocate to upstream watersheds when establishing the TMDL for the 

downstream waterbody;

• Requiring dischargers, at the time of permit issuance, to provide reasonable assurance 

that their effluent does not cause or contribute to nutrient impairments in the receiving 

waterbody and downstream waterbodies; and 

• Identifying trends in nutrient concentrations in all waters, including downstream waters, 

during the assessment cycle. 

WATER QUALITY MODELING

A watershed model, such as WASP or LSPC, can be applied to ensure that the narrative downstream 

water quality standard is achieved when developing and allocating TMDLs and when developing nutrient 

SSACs. The model can be used to ensure that “loading of nutrients from a waterbody shall be limited as 

necessary to provide for the attainment and maintenance of water quality standards in downstream 

waters.” 

ISSUANCE OF NPDES PERMITS 

An upstream regulatory decision, such as a permit issuance, might be executed by evaluating the 

nutrient conditions of near-field and downstream waterbodies. Evaluating near-field conditions was 

described earlier. Downstream evaluations can be conducted similarly. For example, if a downstream 

lake is currently attaining its nutrient standards, then current conditions in the upstream waters provide 

for that attainment condition (i.e., loading of nutrients from the waterbody would be limited at current 

conditions to provide for the continued attainment and maintenance of water quality standards in 

downstream waters). However, a Level II WQBEL will be needed to evaluate the impacts on 

downstream waters if the facility requests an increase in their permitted load. 

If a downstream waterbody is not attaining nutrient standards, the permit could not be issued until 

reasonable assurance was provided that the facility’s discharge was not contributing to the impairment. 

This can be done in response to a Department adopted TMDL, or through independent modeling 

conducted in the watershed. Once modeling is conducted, the results of that modeling can be used to 

ensure that loading of nutrients from the upstream waterbody is limited as necessary to provide for the 

attainment and maintenance of the water quality standards of downstream waters.
30

EVALUATION OF TRENDS 

Even if both upstream and downstream waters are currently attaining nutrient standards or in situations 

where information for downstream waters is not available, the Department’s nutrient standards include 

an evaluation of trends to ensure that conditions are not increased in a manner that could result in 

impairment downstream. Pursuant to Chapter 62-303, F.A.C., the Department assesses whether there is 

an adverse trend in nutrients (nitrate-nitrite, TN or TP) or a nutrient response variable (chlorophyll a) 

and if the waterbody is expected to become impaired. If statistically significant adverse trends are 

present in causal variables, then the waterbody will initially be placed on the Planning List6 of potentially 

impaired waters so that a more rigorous statistical analysis can be conducted. If statistically significant 

adverse trends are present in causal variables after controlling for confounding variables and the 

waterbody is expected to become impaired within 10 years, then the waterbody will be placed on the 

Study List and the Department will develop a site specific interpretation of the NNC for the waterbody. 

This interpretation would likely be a nutrient SSAC, and would be implemented and applied to upstream 

waters feeding the waterbody including in NPDES permits for upstream dischargers as described in the 

section, starting on page 43 herein, titled “WQBEL Procedures for Each Tier of the Hierarchy.” 

If statistically significant adverse trends are present in response variables (after controlling for

confounding variables) and the waterbody is expected to become impaired within 5 years, then the 

waterbody will be placed on the Verified List for nutrient impairment, pursuant to subsection 62-

303.450(4), F.A.C., and a TMDL will be developed, which will be a site-specific interpretation of the NNC

and set levels/allocations to upstream waterbodies. The TMDL, which would include wasteload 

allocations for point sources and load allocations for nonpoint sources, would be implemented in NPDES 

permits for upstream dischargers as described in the section, starting on page 43 herein, titled “WQBEL 

Procedures for Each Tier of the Hierarchy”, and any needed reductions in nonpoint sources would be 

implemented via the BMAP for the TMDL, which is enforceable for nonpoint sources.

When evaluating changes over time, confounding, or exogenous variables, such as natural random 

phenomena (e.g., rainfall, flow, and temperature) often have considerable influence on the response 

variable in question (e.g., nutrient concentration or chlorophyll). By statistically accounting for 

exogenous influences, the background variability is reduced so that any trend present can be better 

observed. This process involves standard statistical modeling, such as least squares regression or 

LOcally WEighted Scatterplot Smoothing (LOWESS) analysis, with a subsequent analysis for increasing 

trend in the residuals. To be considered statistically significant, the p value associated with the residuals 

trend analysis shall be less than 0.05. If the slope of the projected trend line is expected to exceed 

either a nutrient or nutrient response variable endpoint within 10 or 5 years (and if there is evidence of 

anthropogenic nutrient enrichment), the waterbody shall be placed on the Study or Verified List,

respectively. 

This process involves two steps. First, if an increasing trend is determined for nutrients, the Department

analyzes the statistical relationship between nutrients and the associated nutrient response variable to 

 

6 See the Section titled “Implementing the NNC Revisions to the Impaired Water Rule (Chapter 62-303, F.A.C),” 

starting on page 35 herein, for a full description of the Planning, Study and Verified Lists.
31

determine the level of nutrients at which imbalance would occur. Next, the Department would analyze 

the slope of the trend to determine if the response variable would exceed the level associated with 

imbalance within 5 or 10 years, given the trend observed in nutrients.

To illustrate this concept, data were analyzed from Station 3566 in the Weeki Wachee River. Based on 

flow adjusted residuals analysis, the Weeki Wachee River exhibits a statistically significant nitrate-nitrite 

trend. Although there is an apparent trend in the raw data (Figure 4), the influence of flow (Figure 5) 

was taken into account to determine the statistical validity of the trend. Note that the residuals plot 

(Figure 6) shows a more striking trend over time, and that the results are significant (p-value is < 0.001)

with an increasing slope of 0.03 mg/L per month. 

Figure 4. Nitrate concentrations in Weeki Wachee River over time.

Figure 5. Weeki Wachee river flow (CFS) from 1999 to 2011.

COLLECTION.DATE

Nitrate+Nitrite, Total (as N)

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

0.4 0.5 0.6 0.7 0.8 0.9

3566

COLLECTION.DATE

FLOW (cfs)

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

120 140 160 180 200 220 240

3566
32

Figure 6. Weeki Wachee River residuals over time (derived from the flow vs. nitrate regression), 

highlighting the trend during the years from 1999 to 2003.

These data may be used to demonstrate how the Department would implement the adverse trend test, 

which is designed to determine if the water will be impaired within 5 years (for the Verified List), taking 

into consideration the current concentrations of nutrients or nutrient response variables and the slope 

of the trend. For example purposes, suppose the Department had adopted the adverse trend test prior 

to 1999, and suppose that site-specific algal responses in the Weeki Wachee River had led to the 

conclusion that a nitrate level of 0.71 would lead to failures of the Rapid Periphyton Survey. Based on 

the significant trend in the residuals plot, the Department would have estimated that this concentration 

of nitrate (0.71 mg/L ) would be exceeded in 2003, allowing the Department to place the water on the 

verified list in 1999 and take action to reduce nitrate levels prior to the actual impairment occurring. 

While this example focuses on the trends in nutrients in the Weeki Wachee River, it is important to note 

that downstream waters would also be assessed for trends. Any TMDL developed to address the 

increasing trend in nitrate levels would, in addition to protecting the Weeki Wachee River, have the 

added benefit of protecting downstream waters even if there were no observable increases in nutrients 

or nutrient response variable in the downstream waters.

TREND TEST SUMMARY

Because the trend test applies to lakes and estuaries, as well as the streams that feed them, it provides 

an enhanced method to assure that downstream waters are fully protected. In addition to the above

example, if an adverse trend in TP were observed in a downstream lake or estuary, a site specific 

criterion would be developed for the waterbody prior to it becoming impaired, and this action would 

establish TP expectations for upstream waters at a level that would prevent the lake or estuary from 

exceeding the applicable nutrient criteria. The adverse trend test, which is linked to the numeric criteria 

necessary to protect recreation and healthy, well balanced aquatic communities, allows for Hierarchy 1 

COLLECTION.DATE

Residual

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

0.5 0.6 0.7 0.8 0.9

3566
33

site-specific and highly accurate downstream protection values to be developed prior to the 

downstream waters from becoming impaired. 

Discussion of TMDLs as NNC

• Only State-adopted nutrient TMDLs are eligible as site-specific interpretations of the 

NNC. 

• To be eligible, the nutrient TMDLs must be based upon prevention of imbalances of flora 

or fauna (paragraph 62-302.530 (47)(b), F.A.C.). Nutrient TMDLs that address dissolved 

oxygen (DO) impairment (paragraph 62-302.530 (47)(a), F.A.C.) would also be eligible if 

nutrients were identified as a causative pollutant and the TMDL demonstrated that it 

would also prevent an imbalance of natural populations of flora and fauna. As an 

example, surplus anthropogenic nutrients could be shown to generate excess plant 

biomass (periphyton, phytoplankton, or vascular plants), which could by themselves 

constitute an imbalance in flora or result in habitat smothering (e.g., excess periphyton 

accumulation), food web alteration (e.g., dominance of taxa that thrive in nutrient 

enriched conditions), or low DO (from decomposition or respiration of excess plant 

biomass), etc., that results in imbalances in fauna, as reflected by failing SCI scores or 

another meaningful biological endpoint (e.g., decline in seagrass coverage, reduced

transparency, etc.). If the TMDL is written to prevent this cycle and then achieve DO, it 

could be eligible as the numeric interpretation of paragraph 62-302.530 (47)(b), F.A.C.

Standard statistical tests, such as regression or other appropriate empirical or 

deterministic models, are used to demonstrate a “predictable and measurable” DO 

response to nutrients. The p value associated with the regression or other statistical 

model should be less than 0.05 and the variability in DO explained by nutrients should 

be sufficient (e.g., r2

 > 0.25) to expect that nutrient reductions would lead to 

improvements in DO and maintain or restore a healthy, well balanced biological 

community. 

• Many TMDLs are expressed as loads instead of concentrations, but the loads do not 

have to be translated into concentrations to be deemed the numeric interpretation of 

the NNC. 

• TMDLs may be modified based on new data, new science, or different targeted 

endpoints (such as DO). When TMDLs are modified and re-adopted, they become the 

new interpretation of the NNC. 

• Future TMDL rules may include a response target (chlorophyll a, for example) designed 

to implement the NNC. Scientific information relating to the response target and the 

basis for existing TMDLs is presented in the TMDL reports; and this information can be 

used to establish a site-specific listing threshold for nutrient impairment pursuant to 

Rule 62-303.450, F.A.C. 
34

• TMDLs may be written to achieve numeric nutrient values established in Chapter 62-

302, F.A.C., (lakes or springs), or alternatively, to achieve conditions necessary to 

protect the NNC. If written to achieve the NNC, the site-specific thresholds used for the 

TMDL would become the numeric interpretation of the narrative pursuant to “1” of the 

hierarchy. 

• After Rule 62-302.531, F.A.C., becomes effective, subsequently adopted hierarchy 1

nutrient TMDLs must be publically noticed as new numeric interpretations of the 

narrative criterion and as changes to state water quality standards. Consistent with the 

CWA, these site-specific interpretations will be submitted to EPA for review.

Discussion of Site Specific Alternative Criteria as NNC

• The restriction on establishing a Type II SSAC for nutrients pursuant to subsection 62-

303.800(2), F.A.C., was eliminated in the revised rule adopted in December 2011.

• A new SSAC provision for a “Type III SSAC” was also adopted to allow a predictable 

approach to developing nutrient SSACs. The rule language provides clear expectations 

on the water quality and biological data needed to characterize existing nutrient 

concentrations and aquatic health, but the specific number of stations required for 

assessment will be determined on a site specific basis.

• Since numeric nutrient criteria are intended to protect healthy, well-balanced natural 

populations of flora and fauna, the existing nutrient concentrations are deemed 

protective if the biology is found to be healthy and protection of downstream waters is 

demonstrated pursuant to subparagraph 62-302.800(3)(a)3. The nutrient SSAC will 

need to address the natural variability in nutrient concentrations and must demonstrate 

that the designated uses are being protected in the waters covered by the SSAC and in 

downstream waters. 

• As part of Type III SSAC development, aquatic life use support must be demonstrated. 

The phytoplankton, periphyton, vascular plant community, and benthic 

macroinvertebrates responses are used as primary evidence to demonstrate systems are 

meeting their designated use (as described above). 

• Streams that do not exhibit excess algal growth or nuisance aquatic plants and where 

the average of two temporally independent Stream Condition Index (SCI) results is 

greater than 40 are biologically healthy, and the associated nutrient regime is 

demonstrated to be protective. 
35

IMPLEMENTING THE NNC REVISIONS TO THE IMPAIRED 

WATERS RULE (CHAPTER 62-303, F.A.C.)

The Impaired Waters Rule (IWR, Chapter 62-303, F.A.C.) provides a process to determine if waterbodies 

(or waterbody segments) should be placed on the Verified List of impaired waterbodies for subsequent 

TMDL development. The listings are made in accordance with evaluation thresholds, data sufficiency 

and data quality requirements in the IWR. The results of the assessment are used to identify waters in 

each basin for which TMDLs will be developed.

The process for determining impairment in individual waterbodies has been incorporated into the 

Department’s Watershed Management approach. Under this approach, which is based on a 5-year 

basin rotation, Florida’s 52 Hydrologic Unit Code (HUC) basins (51 HUCs plus the Florida Keys) have been 

distributed among 29 basin groups. These basin groups are located within the Department’s six (6) 

statewide districts, with 5 basin groups in each of the Northwest, Central, Southwest, South, and 

Southeast Districts, and 4 basin groups in the Northeast District. One basin group in each district is 

assessed each year (except for the Northeast). Table 6 lists the basin groups for each of the 

Department’s districts that are included in each year of the basin rotation

Implementation of the TMDL Program (monitoring, assessment, identification of impaired waters, 

development of TMDLs, and implementation) under the rotating Watershed Management approach 

includes five distinct phases (Table 7). Development of the Planning, Study, and Verified Lists occur in 

the first two phases of the cycle. As described in greater detail below, there are approximately two 

years between the initial Phase 1 assessment and the final adoption of the Verified Lists [including the 

303(d) list] at the end of Phase 2. 
36 

Table 6. Basin groups for implementing the watershed management cycle, by Department district..

- = No basin assessed

Dept.

District

Group 1

Basins

Group 2

Basins

Group 3

Basins

Group 4

Basins

Group 5

Basins

Northwe

st 

Ochlockonee– 

St. Marks

Apalachicola–

Chipola

Choctawhatch

ee– St. 

Andrew

Pensacola Perdido

Northea

st Suwannee Lower St. Johns - Nassau–St. Marys

Upper East 

Coast

Central Ocklawaha Middle St. 

Johns

Upper St. 

Johns

Kissimmee 

River

Indian River 

Lagoon

Southwe

st Tampa Bay Tampa Bay Tributaries

Sarasota Bay–

Peace–

Myakka

Withlacoochee Springs 

Coast

South

Everglades 

West

Coast

Charlotte 

Harbor

Caloosahatche

e 

Fisheating 

Creek Florida Keys

Southea

st 

Lake 

Okeechobee

St. Lucie–

Loxahatchee

Lake Worth 

Lagoon– 

Palm Beach 

Coast

Southeast 

Coast–

Biscayne Bay

Everglades

Table 7. Phases of the basin management cycle. 

Phase Schedule Activities

Phase 1:

Preliminary Basin 

Evaluation

Year 1

• Identify stakeholders/participants

• Obtain data and enter into Florida STORET

• Conduct public meeting to introduce cycle

• Primary Products: 

 – Develop Planning List of potentially impaired waters to identify those 

waters that need more information to complete a full attainment 

decision. 

 –Develop Strategic Monitoring Plan for information collection to complete a 

full attainment decision. (A full attainment decision allows the 

Department to place waters on the verified list if needed).

Phase 2:

Strategic 

Monitoring and 

Verified List 

Development

Years 2–3 

• Carry out strategic monitoring to collect additional data identified in Phase 1

• Acquire additional data and enter into Florida STORET

• Evaluate new data and incorporate findings into draft versions of Verified List of

 Impaired Waters and Delist List 

• Distribute draft Verified List of Impaired Waters and Delist List for review

• Conduct public meetings and solicit comments from stakeholders on draft

 version of Verified List of Impaired Waters and Delist List 

• Primary Products: 

 –Finalize Verified List of Impaired Waters, Study List, and Delist List for 

Secretarial adoption

 –Adopt Verified List of Impaired Waters and Delist List by Secretarial Order

 –Submit finalized Verified List of Impaired Waters, Study List, and Delist 

List to EPA as update to 303(d) list

Phase 3:

TMDL 

Development 

Years 2–4 • Complete TMDLs for verified impaired waters according to prioritization
37

Phase Schedule Activities

Phase 4:

Development of 

BMAPs

Year 4

• Finalize management goals/objectives

• Develop draft BMAP, including TMDL allocation

• Identify monitoring and management partnerships, needed rule changes and

 legislative action, and funding opportunities

• Develop Monitoring and Evaluation Plans

• Seek funding

• Obtain participant commitment to implement plans

Phase 5:

Implementation

Year 5+ • Implement BMAPs

• Carry out rule development/legislative action

In the first phase of the basin cycle, which lasts approximately six months (from July through December), 

the Department evaluates all readily available water quality data for the basin group using the 

methodology prescribed in the IWR to identify any potentially impaired waters or other waters that 

need additional data to determine the restoration actions needed. For the nutrient assessment, key 

provisions of the IWR include Sections 62-303.350 (Planning List), 62-303.390 (Study List), and 62-

303.450 (Verified List), F.A.C. The Planning List provisions in the IWR for streams (Rule 62-303.351, 

F.A.C.) include two references to the numeric nutrient thresholds for streams (subsection 62-302.531(2), 

F.A.C.). Under subsection 62-303.351(1), F.A.C., streams can be placed on the Planning List for nutrient 

impairment if they do not attain the numeric interpretation of the NNC, which requires a combination of 

both nutrient and biological data to be fully assessed. Under subsection 62-303.351(2), F.A.C., streams 

can also be placed on the Planning List7 if they exceed the numeric thresholds in subparagraph 62-

302.531(2)(c)3, F.A.C., even if there is insufficient biological information to fully assess achievement of 

subsection 62-302.531(2), F.A.C.. 

Waters found to be potentially impaired are included on a Planning List for further assessment, and a 

Strategic Monitoring Plan (SMP) is prepared to ensure that the necessary monitoring is conducted 

during the second phase of the cycle. While the focus of the initial assessment is on the identification of 

potentially impaired waters, the assessment is comprehensive, and waters with sufficient information to 

qualify for the Study List or the Verified List will also be identified. Waters found to be impaired and the 

cause is known to be a pollutant are placed in category 3d to indicate that no additional data are needed 

to place the water on the Verified List in Phase 2. Waters that qualify for the Verified List are generally 

not prioritized for monitoring because sufficient data have already been collected; however, there may 

be cases where the Department may conduct additional monitoring (for example, to confirm the 

causative pollutant or to confirm suspect data). Regardless of whether additional data are collected, the 

waters will not be adopted on the Verified List until the end of Phase II of the cycle. 

The SMP will also address sampling of waters that were placed on the Study List during the previous 

Watershed Management cycle. It should be noted that some of the waters on the Planning List will also 

qualify for the Study List during Phase 1. These waters will not be placed on the official Study List 

submitted to EPA for 303(d) list approval until the conclusion of Phase II and only in those circumstances 

 

7 These waters would also be eligible for the “Study List” if sufficient biological data are not collected during the 

Strategic Monitoring phase.
38

where the needed data or information is not collected during the strategic monitoring phase (due to 

drought, for example). 

The second phase of the Watershed Management cycle includes two distinct activities: completion of 

the SMP and re-assessment of the basin’s waterbodies using the new data. The strategic monitoring 

phase, which lasts a full calendar year, is focused on those waters that were placed on the Planning List 

during the first phase of the basin rotation or the Study List during the previous cycle, with the goal of 

ensuring that sufficient data and/or ancillary information are available to determine (i.e., to “verify”)—

using the methodology described in the IWR—whether a waterbody segment is impaired and if the 

impairment is caused by a pollutant. 

After the monitoring is completed, all of the waterbodies in the basin are re-assessed, taking into 

account the new data collected by the Department and any other new information from other data 

providers. This re-assessment process typically lasts another full calendar year, with draft assessments 

conducted in the spring and presented to the public in June, revised assessments conducted in the 

summer and presented to the public in the fall, and final lists adopted by the Secretary at the end of the 

year. 

Waters are re-assessed for nutrient impairment pursuant to Rule 62-303.450, F.A.C. There has been 

some confusion expressed about the meaning of the text in Rule 62-303.450(3), F.A.C., which states that 

waters shall be placed on the Verified List “upon confirming the imbalance in flora or fauna based on the 

last 7.5 years of data.” The only confirmation required is that the nutrient criteria have been exceeded 

within the last 7.5 years, and no additional biological information is required for waters listed on the 

Planning List under the referenced rule provisions. However, Rule 62-303.450(3), F.A.C., does not 

reference the Planning List rule provision that lists streams on the Planning List based on exceedances of 

the nutrient stream thresholds without sufficient biological information (Rule 62-303.351(2), F.A.C.). 

These waters will be targeted during the SMP so that they can be fully assessed against the numeric 

interpretation of the NNC for streams. 

Waterbody segments identified and verified as impaired are placed on the state’s Verified List of 

impaired waters, and those waterbody segments determined to be no longer impaired or in need of a 

TMDL are placed on the Delist List. After the additional year of data collection, surface waters or 

segments that do not attain surface water quality standards, but the cause of nonattainment is still 

unknown, or waters where there is still insufficient information to fully assess the water quality standard 

are placed on the Study List so that additional monitoring can be conducted to identify the cause of 

impairment or fully implement the water quality standard. 

For waterbodies on the Planning List due to adverse trends in a nutrient or nutrient response variable, 

the Department will conduct additional trend analysis during Phase 2 to determine the appropriate 

listing category for the waterbody. Because it is well known that nutrient loads in natural watersheds 

may fluctuate according to climatologic, hydrologic, and/or seasonal patterns, it is important to control 

for these confounding factors when performing the trend analyses. The Department is confident that 

any increasing trends in anthropogenic nutrient loading will be observed using valid statistical 
39

approaches (e.g., regression and subsequent residuals analyses), because removal of confounding 

influences improves the ability to detect an anthropogenic signal. One of the following actions can 

occur related to trend assessments at the end of the Phase 2 analysis:

1. If the Department determines there is not a statistically significant increasing trend in TN, TP, or 

a nutrient response variable after controlling for confounding variables, then the waterbody will 

be removed from the Planning List for nutrients. 

2. If the Department determines there is a statistically significant increasing trend in TN, TP, or a 

nutrient response variable after controlling for confounding variables and the waterbody is 

expected to become impaired within 6 - 10 years, then it will be placed on the Study List, 

pursuant to paragraph 62-303.390(2)(a), F.A.C.

The waterbody will be removed from the Study List when a site specific interpretation (a SSAC in 

this case) of the NNC is established. If a site-specific interpretation of the narrative has already 

been established, then the waterbody will be re-evaluated to ensure the attainment and 

maintenance of water quality standards in downstream waterbodies.

3. If there is a significant adverse trend in a nutrient response variable and the waterbody is 

expected to become impaired within 5 years, then the waterbody will be placed on the Verified 

List for nutrient impairment, pursuant to subsection 62-303.450(4), F.A.C.

Both the Verified List and Delist Lists are adopted by Secretarial Order in accordance with the Florida 

Watershed Restoration Act (FWRA). Once adopted, the Verified, Delist and Study lists are submitted to 

the EPA for approval as an update to the state’s Section 303(d) list of impaired waters. 

As demonstrated through this process, a waterbody may be placed directly on the Verified List if 

sufficient data are available even if it was not previously identified as potentially impaired in Phase 1 of 

the Watershed Management cycle. Furthermore, there is no requirement that waters be placed on 

either the Planning List or Study List before they can be placed on the Verified List. 

If a waterbody is placed on the Study List, it is the Department’s goal to complete the needed 

monitoring/analysis during either the same or the next Watershed Management cycle. Because waters 

on the Study List will be included on the State’s 303(d) list, there will be significant pressure by both the 

environmental and regulated communities to complete the needed studies in a timely manner. If 

resources allow, the Department will include a second strategic monitoring phase in the Watershed 

Management cycle (likely concurrent with Phase 3, TMDL Development). However, the Department

may need to wait until the Strategic Monitoring phase of the next watershed cycle. As a result, the 

studies should be completed and the waterbody moved to the Verified or Delist List (as appropriate) 

within six years of placement on the Study List. 
40

Assessment of Estuaries

As noted previously, the Department has adopted estuary-specific numeric interpretations of the NNC in 

paragraph 62-302.530(47)(b), F.A.C., for estuaries along the Southwest Coast (roughly from Tampa Bay 

to Miami and the Florida Keys). With the exception of the criteria developed for Tampa Bay, which are 

expressed as delivery ratios (addressed in next section), assessment of the estuary-specific numeric 

interpretations is straightforward because the listing thresholds for both the Planning and Verified Lists 

are directly based on exceedances of the adopted numeric interpretations of the NNC [see Subsections 

62-303.353(1), and 62-303.450(3), F.A.C.] For this assessment, the only added review elements under 

the IWR include the time frame (10 years for Planning List and 7 years for the Verified List) and an 

evaluation of whether the data were collected under extreme climatic conditions (the Department will 

not list waters as impaired based solely on extreme climatic conditions or changes in the monitoring 

network).

For estuarine systems without adopted estuary-specific numeric interpretations of the NNC, the 

Department will continue to assess the NNC pursuant to Subsection 62-303.353(3), F.A.C. (Planning List) 

and Subsection 62-303.450(2), F.A.C. (Verified List), and assess the 11 ug/l chlorophyll a impairment 

threshold for estuaries pursuant to Subsection 62-303.353(2) (Planning List) and Subsection 62-

303.450(1), F.A.C. (Verified List).
41

Assessment of Waterbodies with Interpretations of the NNC

Expressed as Loads or Delivery Ratios

For waters with nutrient TMDLs expressed as a load, attainment of the allowable loads will be evaluated 

as part of the BMAP reporting process, and nonattainment will be assumed until information is provided 

to prove attainment (a combination of model estimated loads of nonpoint sources and measured loads 

from point sources). Waters should only be deemed to be in attainment if they meet the loads (or 

concentrations) and targets (e.g., chlorophyll) and a demonstration is made that nutrients are no longer 

causing biological imbalances. If the waterbody attains the allowable loading but there is site-specific 

information indicating an imbalance in flora or fauna, the TMDL would be revisited and revised as 

needed.

For the Tampa Bay estuarine system where nutrient standards are expressed as a delivery ratio, the 

Tampa Bay Estuary Program has agreed, pursuant to their binding Reasonable Assurance agreement, to 

provide the hydrologic and loading information (for both point and nonpoint sources) needed to 

calculate and assess annual delivery ratios on at least a five year frequency, which is consistent with 

DEPs watershed assessment cycle. However, TBEP has agreed to evaluate chlorophyll a targets on an 

annual basis, and will provide the Department with the needed information more frequently if 

chlorophyll a targets are exceeded for two consecutive years. 

IMPAIRED WATERS RULE ASSESSMENT SUMMARY

• The IWR was revised to be consistent with the revisions to Chapter 62-302, F.A.C., 

including provisions to implement the NNC for lakes, springs, and streams. 

• Streams that exceed reference-based nutrient thresholds will be placed on the Study List 

unless there are bioassessment data (flora and fauna) indicating the stream is healthy. 

Streams that exceed reference-based nutrient thresholds and have information that 

indicate imbalances of flora are placed directly on the Verified List. Waters on the Study 

List will receive a site-specific physical, chemical, and biological investigation to 

determine if aquatic life use support goals are attained (if there were no bioassessment 

data available), and if aquatic life use support is not attained, to determine the 

causative pollutant(s). This process constitutes a “stressor identification” study. If the 

stream is determined to be impaired due to nutrients (at least in part), the water will be 

listed on the Verified List for TMDL development, which will determine the reductions 

needed. This approach places waters on the Study List if there is a nonattainment 

condition based on the current numeric interpretation of the narrative criterion outlined 

above, and places waters on the IWR Verified List for nutrients if they need a reduction 

in a nutrient loading to attain the NNC or otherwise restore the waterbody’s designated 

use. 
42

SURFACE WATER DISCHARGE WASTEWATER PERMITS

This chapter describes how the site-specific interpretations of the NNC in Rules 62-302.531 and 62-

302.532, F.A.C., are implemented in surface water discharge domestic and industrial wastewater 

permits with reasonable potential (excluding municipal separate storm sewer system permits)(see 

Figure 7), including:

• The permit application process;

• The expectations for providing reasonable assurance and for calculating Water Quality 

Based Effluent Limitations for nutrients; and 

• How permits will be reviewed with respect to meeting numeric nutrient standards both 

in near-field receiving waterbodies as well as downstream waterbodies. 

Figure 7. Flow chart illustrating the process by which NNC will be implemented in surface water 

discharge wastewater permits.

Although it is ultimately the Department’s responsibility to assure that adequate documentation is in 

the administrative record for permitting decisions, Florida’s permitting process puts the burden on the 

applicant to provide all of the necessary documentation for permit issuance. Rule 62-620.320, F.A.C., 

(Standards for Issuing or Denying Permits) requires that:

“(1) A permit shall be issued only if the applicant affirmatively provides the Department with 

reasonable assurance, based on a preliminary design report, plans, test results, installation of 

pollution control equipment, or other information, that the construction, modification, or operation of 

the wastewater facility or activity will not discharge or cause pollution in contravention of chapter 

403, F.S., and applicable Department rules. 
43

(2) If, after review of the application and any pertinent information, the Department determines 

that the applicant has not provided reasonable assurance that the construction, modification, or 

operation of the wastewater facility or activity will be in accordance with applicable statutes or rules, 

including rules of approved local programs under 403.182, F.S., the Department shall deny the permit, 

shall notify the applicant, and specify the reasons for the denial.” 

These information requirements are spelled out in the Department’s “Guide to Permitting Wastewater 

Facilities or Activities Under Chapter 62-620, F.A.C.” The guide reiterates the rule requirement that the 

applicant has the burden to submit documentation with the application providing reasonable assurances 

that the criteria in Chapter 62-302, F.A.C., and other applicable Department rules shall be met. If other 

Department orders or rules have established discharge limits that explicitly protect the narrative 

standard (in-stream, upstream, and downstream) in this type of segment, that limit is sufficient to 

implement numeric nutrient criteria as long as it continues to implement the standards at Rule 62-

302.531(2), F.A.C.

The WQBEL process, pursuant to Chapter 62-650, F.A.C., is the mechanism for determining the levels of 

nutrients in a point source discharge (i.e., effluent nutrient limits) that attain the NNC in paragraph 62-

302.530(47)(b), F.A.C. Derivation of a level II nutrient WQBEL is a site-specific, hierarchy 1 interpretation 

of the NNC and the WQBEL derivation is based on the worst-case scenario (permitted flows) and the 

associated nutrient loads from a discharge. If downstream waters are anticipated to be potentially 

affected by the discharge of nutrients from an upstream facility, the potential impact must be assessed, 

regardless of distance (see section on “NNC and Protection of Downstream Waters”). 

Revisions to a WQBEL for existing discharges are implemented through the permit renewal process and 

compliance schedules may be used to give permittees time to come into compliance with any new 

requirements pursuant to the provisions of subsection 403.088(2)(e) and (f), F.S., and subsections 62-

620.610(12) and 62-620.620(6), F.A.C. New or expanded discharges are subject to the antidegradation 

review, and if the discharge contains nutrients, it will need to have a WQBEL established and provide 

reasonable assurance at the time the permit is issued that the WQBEL will be met. Existing WQBELs are 

reviewed at the time of permit renewal (every five years), and if the factors associated with the 

derivation of the WQBEL have not substantively changed during the five year period, the WQBEL can be 

considered valid for another five year period.

WQBEL PROCEDURES FOR EACH TIER OF THE HIERARCHY

1. In accordance with paragraph 62-302.531(2)(a), F.A.C., where a site specific numeric interpretation 

of paragraph 62-302.530(47)(b), F.A.C., has been established by the Department, that interpretation 

is the applicable interpretation. Such interpretations include Total Maximum Daily Loads (TMDLs), 

site specific alternative criteria (SSAC) for nutrients, Reasonable Assurance (RA) demonstrations, or 

other site-specific interpretations that are formally established by rule or final order of the 

Department. The applicable interpretations, if available, include both nutrient [e.g., total nitrogen 

(TN) or total phosphorus (TP)] and response variables (e.g., chlorophyll a). Where multiple 

interpretations have been made for a waterbody, the most recent is the applicable interpretation. If 

only one nutrient (e.g., TP) has a numeric interpretation established in accordance with paragraph
44

62-302.531(2)(a), F.A.C., the numeric interpretation of the narrative nutrient criteria for the other 

nutrient (e.g., TN) follows the hierarchy described in paragraph 62-302.531(2), F.A.C. The 

Department will maintain a listing of the site-interpretations established to date available on the 

Department website. 

Site-specific interpretations are used to establish WQBELs as follows:

• TMDLs – Where a TMDL8 is the applicable interpretation, a WQBEL is derived in 

accordance with the Wasteload Allocation provided in the TMDL. In accordance with 

subsection 62-302.531(8), F.A.C., if the Wasteload Allocation is expressed as a load, the 

WQBEL can be expressed as a load9 (i.e., there is no requirement to “translate” the load 

to a concentration for the WQBEL).

• SSAC – Where a SSAC is the applicable interpretation, a WQBEL is derived to ensure that 

the discharge does not cause or contribute to an exceedance of the SSAC within the 

spatial area to which the SSAC is applicable (e.g., if a SSAC for a stream segment has 

been established as an annual geometric mean of 40 μg/L total phosphorus, the WQBEL 

is calculated to ensure that the discharge does not cause or contribute to the stream 

segment exceeding an annual geometric mean of 40 μg/L), in all years. If the 

waterbody currently achieves the SSAC value, the Level I WQBEL process can be used to 

establish effluent limits consistent with permitted nutrient levels, but only if the permit 

applicant is not expanding its discharge above currently permitted levels and will not 

increase its nutrient concentrations over the permit cycle. However, if the waterbody 

does not achieve the SSAC or if the permit is for a new or expanded discharge, the Level 

II WQBEL process is more appropriate.

• Reasonable Assurance (RA) Demonstration – Where the Department has approved an 

RA demonstration pursuant to the subsection 62-303.100(5), F.A.C., related to nutrient 

impairment, the nutrient-related target in the RA demonstration can serve as the 

applicable numeric interpretation of the narrative nutrient standard. The WQBEL would 

then be calculated to ensure attainment of that numeric interpretation in the same 

manner as the TMDL or SSAC procedures, depending on how the RA demonstration was 

crafted. For example, if the RA demonstration included an allocation to a permitted 

facility, that allocation can be treated as the Wasteload Allocation similar to those 

contained in a TMDL.

For the examples above that include a Wasteload Allocation, the WQBEL is established using the 

Level I process at Rule 62-650.400, F.A.C., to implement the site-specific interpretation of the 

narrative. If the Department determined that a facility will not cause or contribute to nutrient 

impairment and did not establish a Wasteload Allocation for the facility, permit limits are not 

required, pursuant to the TMDL; however, such a facility would not be allowed to increase its 

 

8 TMDL means a TMDL adopted under Chapter 62-304, F.A.C., that interprets the narrative water quality criterion 

for nutrients in paragraph 62-302.530(47)(b), F.A.C., for one or more nutrients or nutrient response variables. 9 Note – permit load (mass) limits are generally expressed as a rolling annual load.
45

nutrient loading and permit limits may be needed if increased discharge is being sought. Where a 

TMDL, SSAC or RA Demonstration does not exist, a WQBEL is recognized as the applicable

interpretation of the narrative nutrient criteria if:

a) The documentation for the WQBEL includes a site specific numeric interpretation of the 

narrative criterion at paragraph 62-302.530(47)(b), F.A.C., for the waterbody; 

b) The WQBEL is established pursuant to the Level II Process contained at Rule 62-650.500, 

F.A.C.; and 

c) The public notice for the WQBEL specifically states that the Level II WQBEL includes a site 

specific interpretation of the narrative for the receiving waterbody. 

Where a Level II WQBEL has previously been established for discharge of nutrients to a waterbody 

and a TMDL, SSAC, or RA does not exist for the waterbody, the existing WQBEL remains in effect 

until revised by a Final Order that establishes a site specific interpretation of the narrative. 

Revisions to the WQBEL to reflect the site-specific interpretation will generally be implemented 

through the permit renewal process, and compliance schedules are used to give permittees time to 

come into compliance with any new requirements pursuant to the provisions of paragraphs 

403.088(2)(e) and (f), F.S., and subsections 62-620.610(12) and 62-620.620(6), F.A.C. In certain 

cases permits may need to be re-opened prior to permit renewal to include revised WQBELs based 

on priority of restoration needs, time remaining before permit renewal, and workload 

considerations. 

2. If there is no site-specific interpretation in effect as described in the preceding paragraph that is 

applicable to the receiving waters, but there is an established, quantifiable stressor response 

relationship between one or more nutrients and nutrient response variables for those waters, then 

the values set forth in paragraph 62-302.531(2)(b), F.A.C., are the applicable numeric interpretation

of paragraph 62-302.530(47)(b), F.A.C. Such an interpretation has only been made at this time for 

lakes and spring vents. There are currently no discharges directly to spring vents and it is unlikely 

that such discharges will be proposed in the future. Effluent limits for discharges to ground waters 

in the springshed are developed through the standard process for groundwater discharges (see 

separate document on discharges to groundwater) or through the TMDL/Basin Management Action 

Plan process for that spring where sufficient information exists. 

For lakes, the WQBEL may be derived to ensure that the discharge does not cause or contribute to 

exceedances of the numeric interpretation for the waterbody segment, which is expressed as a lake 

average. As stated previously, Florida’s wastewater permitting process puts the burden on the 

applicant to provide all of the necessary documentation for permit issuance, including 

demonstrating that their discharge will not cause violations of the water quality standards 

applicable to the lake. Depending on the circumstances of the lake, either a Level I or Level II WQBEL 

is established that implements this numeric interpretation of the narrative criteria. This is 

accomplished as follows: 
46

• If the discharge can meet the applicable numeric interpretation, a Level I WQBEL is 

calculated to ensure the discharge does not exceed the Total Nitrogen and Total 

Phosphorus values contained in sub-subparagraph 62-302.531(2)(b)1.a., F.A.C.; or 

• For existing discharges, a Level I WQBEL can be established at permitted nutrient loads 

if the receiving lake attains the numeric interpretation of the narrative expressed at subsubparagraph 62-302.531(2)(b)1.a., F.A.C.; or 

• For new or expanded discharges to a lake that attains the applicable criteria, a Level II 

WQBEL must be established that ensures the lake will continue to attain the numeric 

interpretation of the narrative; or 

• If the lake does not attain the baseline TN or TP values in sub-subparagraph 62-

302.531(2)(b)1.a., F.A.C., but attains the applicable chlorophyll a value in subsubparagraph 62-302.531(2)(b)1.a., F.A.C., a Level II WQBEL must ensure attainment of 

the applicable chlorophyll a value in all years. The Level II WQBEL must also ensure that 

ambient lake nutrient conditions do not exceed the upper end of the range Total 

Nitrogen and Total Phosphorus limits in sub-subparagraph 62-302.531(2)(b)1.b., F.A.C. 

In any case, a new or expanded discharge would need to conduct water quality modeling during 

critical conditions to provide the reasonable assurance that the discharge will not cause a violation 

of lake water quality standards during critical conditions. Note that the WQBEL is subject to change 

upon permit renewal if a site specific interpretation is established pursuant to paragraph 62-

302.531(2)(a), F.A.C. 

3. For streams in which an applicable interpretation (i.e., TMDL, SSAC, RA) has not been made as 

described in paragraph 1, the provisions set forth in paragraph 62-302.531(2)(c), F.A.C., are the 

applicable numeric interpretation of paragraph 62-302.530(47)(b), F.A.C. A continuous discharge 

facility that has effluent nutrient concentrations greater than the applicable numeric nutrient 

thresholds adopted at Subparagraph 62-302.531(2)(c)2, F.A.C., will require that effluent limits be 

established as necessary to meet the nutrient standards in Chapter 62-302, F.A.C. In that case, a 

WQBEL that implements the numeric interpretation of the narrative criteria is derived as follows:

• If the stream receiving an existing discharge has evidence of balanced flora based on 

available information on chlorophyll a levels, algal mats or blooms, nuisance 

macrophyte growth, and changes in algal species composition and either is achieving 

the reference thresholds at subparagraph 62-302.531(2)(c)2., F.A.C., or there is evidence 

of balanced fauna based on available Stream Condition Index (SCI) scores10, the 

waterbody will be deemed to have attained the standard at paragraph 62-

302.531(2)(c), F.A.C., and the narrative criterion of paragraph 62-302.530(47)(b), F.A.C. 

In that case, the Level I WQBEL process is used to establish effluent limits consistent 

with permitted nutrient loads if the permit applicant is not expanding its discharge 

 

10 See Section 2.7 of the SCI Primer for details on the floral assessment.
47

above currently permitted levels and will not increase their nutrient concentrations over 

the permit cycle. However, if a facility is discharging significantly below its permitted 

capacity, the Department will review the WQBEL that was the basis for the current 

permit limits to ensure that it is still a valid interpretation of the NNC. The Level II 

WQBEL process is available for new discharges or facility expansions that result in 

increased nutrient loads11. A WQBEL for a new or expanded nutrient discharge must 

ensure that a healthy, well balanced floral community will be attained at the proposed 

discharge, and that either the nutrient thresholds will be achieved in the receiving 

stream (averaged over appropriate stream segments with homogeneous water quality) 

or that the waterbody has healthy fauna (SCI). If SCI measurements indicate that the 

waterbody is not biologically healthy AND a stressor identification study indicates that 

nutrients are the cause, the WQBEL that prevents nutrients from impacting stream 

fauna would need to be calculated. 

If insufficient biological data are available12 to determine if the stream is healthy, pursuant to 

paragraph 62-302.531(2)(c), F.A.C., the applicant may collect additional biological data to provide 

reasonable assurances. If the additional biological data indicate that the stream is not healthy, 

the following scenario will apply.

• If the stream receiving an existing discharge has evidence of imbalance in flora based on 

available information on chlorophyll a levels, algal mats or blooms, nuisance 

macrophyte growth, then the waterbody is not achieving the narrative criterion of 

paragraph 62-302.530(47)(b), F.A.C., regardless of whether the reference thresholds at 

paragraph 62-302.531(2)(c), F.A.C. or the SCI thresholds are met. If the flora are 

determined to be healthy, but neither the reference thresholds at subparagraph 62-

302.531(2)(c)2., F.A.C., nor the SCI thresholds are met, then the waterbody is also not 

achieving the narrative criterion of paragraph 62-302.530(47)(b), F.A.C. In that case, 

the discharge to that waterbody is not allowed unless a level II WQBEL is developed or 

other administrative process is implemented that ensures the discharge does not cause 

or contribute to nonattainment of subparagraph 62-302.531(2)(c)2., F.A.C. or the 

narrative criterion of paragraph 62-302.530(47)(b), F.A.C. In the circumstance where 

flora are balanced, but the SCI fails, a stressor identification study would likely be 

needed as part of the Level II WQBEL evaluation. Stressor identification studies evaluate 

and identify causes of biological impairment, including both pollutant and 

hydrologic/habitat related stressors. 

Where a stream is verified as impaired for nutrients pursuant to the impaired waters rule, a sitespecific interpretation of the narrative nutrient standard will be developed as part of the TMDL 

 

11 Since paragraph 62-302.532(7)(d), F.A.C., specifies that the spatial application of the numeric interpretation shall 

be determined by relative stream homogeneity and shall be applied to waterbody segments or aggregations of 

segments as determined by the site-specific considerations, mixing zones are not applicable. 12 Biological data are available to the applicant through the Department’s website at 

http://ca.dep.state.fl.us/mapdirect/?focus=waterdatacentral
48

process, which will include Wasteload Allocations for discharges to the stream. The subsequent 

WQBEL would be consistent with the Wasteload Allocation. As noted previously, the WQBEL is 

subject to change upon permit renewal if a site specific interpretation is established pursuant to 

paragraph 62-302.531(2)(a), F.A.C. 

WQBELs established by all of the above methods must prevent discharges from causing or contributing 

to a violation of the NNC in paragraph 62-302.530(47)(b), F.A.C. Also, in accordance with Subsection 62-

302.531(4), F.A.C., WQBELs cannot allow the loading of nutrients from a waterbody to cause or 

contribute to an exceedance of water quality standards in a downstream waterbody. The reasonable 

assurance demonstration that the construction, modification, or operation of the wastewater facility or 

activity will meet this requirement may include information that: a) water quality standards of 

downstream waters are being attained with the existing discharge, b) the existing or future discharge 

does or will not affect downstream waters, or c) the discharge is in compliance with downstream 

TMDLs.

Finally, a permittee has the option of pursuing relief from any of the above site-specific interpretations 

through the establishment of Site Specific Alternative Criteria under Rule 62-302.800, F.A.C., a variance 

under the provisions of 403.201, F.S., or a designated use modification under Rule 62-302.400, F.A.C.
49

BASIC Information Needs for Distinguishing Flowing Waters under 62-

302.200(36) F.A.C.

The definition of stream in Rule 62-302.200(36), F.A.C., states: 

(36) “Stream” shall mean, for purposes of interpreting the narrative nutrient criterion in 

paragraph 62-302.530(47)(b), F.A.C., under paragraph 62-302.531(2)(c), F.A.C., a predominantly 

fresh surface waterbody with perennial flow in a defined channel with banks during typical 

climatic and hydrologic conditions for its region within the state. During periods of drought, 

portions of a stream channel may exhibit a dry bed, but wetted pools are typically still present 

during these conditions. Streams do not include:

(a) Non-perennial water segments where fluctuating hydrologic conditions, including 

periods of desiccation, typically result in the dominance of wetland and/or terrestrial taxa (and 

corresponding reduction in obligate fluvial or lotic taxa), wetlands, portions of streams that 

exhibit lake characteristics (e.g., long water residence time, increased width, or predominance 

of biological taxa typically found in non-flowing conditions), or tidally influenced segments that 

fluctuate between predominantly marine and predominantly fresh waters during typical climatic 

and hydrologic conditions; or

(b) Ditches, canals and other conveyances, or segments of conveyances, that are manmade, or predominantly channelized or predominantly physically altered; and

1. Are primarily used for water management purposes, such as flood protection, 

stormwater management, irrigation, or water supply; and

2. Have marginal or poor stream habitat or habitat components, such as a lack of habitat 

or substrate that is biologically limited, because the conveyance has cross sections that are 

predominantly trapezoidal, has armored banks, or is maintained primarily for water conveyance.

The Department applies relevant water quality standards while implementing programs such as 

assessing waterbodies for attainment of water quality standards under 403.067, F.S., or implementing 

the NPDES permitting programs. When applying the nutrient standards adopted in Rule 62-302.531(2), 

F.A.C., the Department will make clear whether the standards for streams adopted in Rule 62-

302.531(2)(c), F.A.C., are applicable. In implementing water quality standards and evaluating whether a 

particular waterbody meets the provisions of 62-302.200(36)(a) or (b) F.A.C., the Department will 

provide public notice and request information relevant to the application of water quality standards, 

including the purpose of the waterbody such as flood protection, stormwater management, irrigation, 

water supply, navigation, boat access to an adjacent waterbody, or frequent recreational use relevant to 

62-302.200(36)(b)1. F.A.C. The Department will consider all relevant information in implementing water 

quality standards and maintain the administrative records of such decisions, which are available to the 

public. 
50

General Information

Until a Class I or III stream segment is identified as meeting the provisions in Rule 62-302.200(36)(a) or

(b), F.A.C., the criteria in Rule 62-302.531(2)(c), F.A.C., will apply. Interested parties wishing to 

distinguish the characteristics of a waterbody with respect to provisions in Rule 62-302.200(36), F.A.C., 

may provide the Department with the applicable information set forth in the stream definition. 

A clear delineation of the geographic boundaries of the segment in question is necessary so that the 

Department knows exactly where applicable criteria apply. Delineation of segment boundaries can 

include physical, biological, and chemical information, such as intersections of tributaries into a 

segment, control structures, the interface of wetlands, or other factors that indicate that the 

homogeneous physical, biological, or chemical condition of the segment would change at the boundary. 

For waters that meet the definition of 62-302.200(36)(a) or (b) F.A.C., the Department shall follow the 

Impaired Waters Rule at 62-303 F.A.C. 

Non-Perennial Water Segments

The stream nutrient water quality standards adopted by the Department are not designed to apply to 

wetlands or uplands. The method for identifying non-perennial water segments is fundamentally based 

on the use of biological information to indicate the long term hydrologic condition of the water 

segment. Specific biological taxa can indicate where a perennial stream segment transitions to a system 

more characteristic of wetland or upland conditions. 

To identify whether a segment is a non-perennial water segment, the biological information identified 

below will be evaluated by the Department. Other methods that provide this demonstration with 

similar accuracy will be accepted by the Department if they are a means to predicting the resulting 

biological conditions discussed below. 

VASCULAR PLANTS AS INDICATORS

Many plants and animals are adapted to survive in a specific hydrologic regime. The Department has 

long relied on lists of vascular plants (including obligate wetland indicators, facultative wetland 

indicators, and facultative (neutral indicators) as one component of the method used to identify and 

delineate wetland boundaries, as defined in Chapter 62-340, F.A.C. If available, vascular plant 

community composition will be used to assist in distinguishing streams from non-perennial water 

segments. Often, both of these types of systems contain few or no rooted herbaceous plants in the 

stream channel, because natural turbidity, canopy cover, and color reduce the light available for 

photosynthesis. If there are herbaceous plants present, perennial and non-perennial systems often 

share many taxa, particularly in areas where they transition to adjacent floodplains. However, the 

presence of certain facultative or facultative-wetland herbaceous species within the stream bed can be 

a valid indication that the stream is non-perennial, as these taxa may require moist or saturated 

conditions to germinate and grow, but would not tolerate the inundation of a perennially flowing 

stream. Examples of these taxa include, grasses such as Chasmanthium latifolium and Tripsacum 

dactyloides, sedges such as Cyperus esculentus and Cyperus retrorsus, forbs such as Cuphea 

cartagenensis, Bidens pilosa, and Sphagneticola trilobata, and ferns such as Woodwardia virginica and 
51

Thelypteris spp. (see complete lists of obligate wetland, facultative wetland and facultative taxa in 

Chapter 62-340, F.A.C.). During a habitat assessment or Linear Vegetation Survey conducted during a 

site visit, the presence of facultative and facultative wetland herbaceous vascular plant taxa in the 

channel bed would be an indicator that the system is non-perennial. Many plants within a permanently 

wetted channel are aquatic plants, which are defined but not listed in Chapter 62-340, F.A.C. Under 

extreme dry conditions, terrestrial taxa could also invade the channel bed of a non-perennial system.

MACROINVERTEBRATES AS INDICATORS

If available, macroinvertebrates will be used to distinguish perennial from non-perennial /wetland 

systems. Many invertebrates (rheophyllic taxa) require relatively consistent inundation and water 

velocity to complete their life cycle, although they have mechanisms to survive extreme drought 

conditions, when perennial streams may be reduced to a series of pools. Other (mostly wetland) taxa 

are adapted to survive the frequent (generally annual) periods of desiccation associated with nonperennial streams or wetlands. Some invertebrate species could be classified as facultative, able to

occupy both perennial and non-perennial streams. This similarity in fauna is due in part to colonization 

of non-perennial streams by movement of invertebrates from nearby perennial waters, especially those 

with adaptations that allow them to survive in temporary environments, such as a multivoltine life cycle, 

highly mobile adults, and rapid growth during the wet season. Some rarely inundated non-perennial 

streams may be either completely lacking in aquatic invertebrates (terrestrial animals may be present), 

or have a limited number of facultative species that can complete their life cycles rapidly before the 

stream dries. 

The Department has compiled lists of taxa to assist with distinguishing perennial from non-perennial 

streams/wetland systems (Tables 8 and 9). Rule 62-302.531(2)(c), F.A.C., does not apply to nonperennial water segments where there is a dominance of wetland and/or terrestrial taxa (and 

corresponding reduction in obligate fluvial or lotic taxa) or to wetlands. Rule 62-302.531(2)(c), F.A.C.,

does apply to perennial streams where drought conditions result in portions of a stream channel 

temporarily exhibiting a dry bed, but where wetted pools are still present. 

Stream Condition Index (“SCI”) sampling, the method normally used to collect stream invertebrate taxa, 

requires certain hydrologic conditions to distinguish the effects of natural drought from water quality 

issues. SCI sampling (following DEP Standard Operating Procedure SCI 1000) is conducted during 

periods when water velocity has been 0.05 m/sec or greater for at least 28 days or after a 6 month 

period if the site has gone completely dry. Following these SOPs ensures that perennial streams are 

typically dominated by taxa from Table 8, while non-perennial systems (which tend to transition into 

linear wetland strands) either would usually not be sampled for SCI or would typically be dominated by 

taxa in Table 9. The presence of long-lived aquatic species (benthic macroinvertebrates that require 

water for their entire life cycle) is another reliable method to determine if a stream is more 

characterized by perennial flow or wetland/terrestrial conditions. A list of long-lived taxa is included in 

DEP SOP SCI 2100. 
52

For purposes of establishing segments that are excluded from the stream definition, the Department 

shall evaluate the taxa that occur in the segment, as well as the vascular plant information described 

above. 

Table 8. The most commonly encountered invertebrate taxa in flowing streams in Florida. Taxa 

information was retrieved from the Florida Statewide Biological DataBase (“SBIO”) and represents 5,309 

perennial stream samples collected over the entire state. Some of the organisms are ubiquitous (e.g., 

Chironomidae) and are found in several system types, however, in flowing systems there are a large 

number of rheophyllic and long-lived taxa that are not commonly encountered in wetlands or nonperennial streams.

Taxa # occurrences (n = 5309)

Hyalella azteca 3918

Stenelmis 3715

Cheumatopsyche 3515

Caenis (except C. diminuta) 3162

Rheotanytarsus exiguus grp. 3028

Microcylloepus pusillus 2913

Stenochironomus 2769

Dubiraphia vittata 2588

Polypedilum flavum 2575

Simulium 2503

Ablabesmyia mallochi 2402

Polypedilum scalaenum grp. 2222

Tubificidae 2056

Argia (except A. sedula) 2022

Oecetis 1992

Hydroptila 1990

Pentaneura inconspicua 1889

Palpomyia/bezzia grp. 1821

Tanytarsus sp. c epler 1780

Hemerodromia 1752

Corbicula fluminea 1696

Tanytarsus sp. l epler 1641

Hydrobiidae 1639

Enallagma 1590

Hydropsyche 1587

Baetidae 1533

Tricorythodes albilineatus 1516

Tanytarsus 1510

Caecidotea 1490

Micromenetus 1428

Sphaeriidae(mollusca) 1367

Neotrichia 1362

Thienemannimyia grp. 1347

Triaenodes 1315
53

Limnodrilus hoffmeisteri 1311

Pseudochironomus 1288

Heptageniidae (except Stenacron 

interpunctatum)

1286

Palaemonetes 1274

Ancyronyx variegatus 1256

Rheotanytarsus pellucidus 1156

Chimarra 1149

Cryptochironomus 1139

Cambaridae 1131

Table 9. The most abundant invertebrate taxa found in wetland systems in Florida from 169 samples 

retrieved from SBIO. The organisms are dominated by oligochaetes (e.g., represented by the genera 

Dero, Bratislavia and others), midges (e.g., Polypedilum and Goeldichironomus), and damselflies and 

dragonflies (e.g., Coenagrionidae and Libellulidae).

Taxon # of occurrences (n = 169)

Chironomus 105

Dero digitata complex 98

Polypedilum trigonum 96

Kiefferulus 80

Polypedilum tritum 67

Chaoborus 65

Libellulidae 65

Culicidae 60

Hydrocanthus 59

Enchytraeidae 58

Monopelopia boliekae 58

Goeldichironomus holoprasinus 56

Berosus 56

Dero 55

Dero vaga 51

Goeldichironomus 49

Dero pectinata 47

Bratislavia unidentata 46

Odonata 42

Dytiscidae 42

Dero lodeni 39

Oribatei 39

Aeshnidae (except Boyeria and 

Nasiaeschna)

38

Haemonais waldvogeli 36

Goeldichironomus natans 35

Belostoma 35

Uranotaenia 34
54

Pristinella longisoma 32

Callibaetis 32

Larsia berneri 31

Gastropoda 31

Pachydiplax longipennis 31

Arrenurus 30

Curculionidae 30

Pristina leidyi 28

Hydrovatus 28

Crangonyx 26

Pristina aequiseta 26

Buenoa 26

Anopheles 26

Callibaetis floridanus 25

Atrichopogon 25

Larsia 25

Corixidae 25

Pristina 25

Tidally Influenced Segments 

Tidally influenced segments are those that fluctuate (daily, weekly, or seasonally) between 

predominantly marine and predominantly fresh waters during typical climactic and hydrologic 

conditions. The delineation of the segment is important as only portions of segments that are 

demonstrated to fluctuate between marine and fresh conditions are applicable under Rule 62-

302.200(36)(a), F.A.C. The definitions of predominantly fresh and predominantly marine waters in Rule 

62-302.200, F.A.C., are as follows:

(29) “Predominantly fresh waters” shall mean surface waters in which the chloride 

concentration is less than 1,500 milligrams per liter or specific conductance is less than 4,580 

μmhos/cm.

(30) “Predominantly marine waters” shall mean surface waters in which the chloride 

concentration is greater than or equal to 1,500 milligrams per liter or specific conductance is 

greater than or equal to 4,580 μmhos/cm.

This distinction can be made with chloride or specific conductance data that were collected during 

typical hydrologic conditions, taking into account tidal cycles and seasonal and climatic variability. The 

presence of typical hydrologic conditions may be shown by tide and flow data that are temporally 

coupled with the water quality sampling events. The information (continuous or frequent grab sampling 

data) that demonstrates changing salinity conditions during a typical tidal cycle is necessary for the 

Department to differentiate the streams coverage under Rule 62-302.200(36), F.A.C. 

Typical hydrologic conditions exclude periods of high rainfall or drought that would create flow 

conditions well outside of average annual flow conditions.
55

Domestic and industrial wastewater discharges with reasonable potential to discharge nitrogen and 

phosphorus in concentrations that can cause or contribute to nutrient impairments will receive water 

quality based effluent limits (WQBELs) consistent with Chapter 62-650, F.A.C., for total nitrogen and 

total phosphorus that implement State water quality standards related to nutrients (narrative and 

numeric). Florida has approximately 40 domestic and industrial discharges directly to tidally influenced 

segments of flowing waters with the reasonable potential to cause or contribute to nutrient 

impairments. 

As part of the NPDES permitting process for domestic and industrial discharges, existing Florida law 

requires that such dischargers need to provide reasonable assurance that nutrient water quality 

standards will not be violated as a result of their discharge. For those waters that qualify as tidally 

influenced segments under Rule 62-302.200(36)(a), F.A.C., the water quality standards in Rule 62-

302.531(2)(c), F.A.C., do not apply. WQBELs for NPDES permitted domestic and industrial wastewater 

discharges into such tidal segments will be based on the applicable numeric nutrient standards in waters 

both downstream (estuaries) and upstream (if tidally influenced), as well as the narrative nutrient water 

quality standard at the point of discharge. The establishment of numeric nutrient water quality 

standards in downstream and upstream waterbodies will expedite the derivation of WQBELs for 

discharges to these tidal segments. If other Department orders or rules have established discharge 

limits that explicitly protect the narrative standard (in-stream, upstream, and downstream) in this type 

of segment, that limit is sufficient to implement numeric nutrient criteria as long as it continues to 

implement the standards at Rule 62-302.531(2), F.A.C. 

Water Management Conveyances

The stream definition in Rule 62-302.200(36)(b), F.A.C., excludes the following: Ditches, canals and 

other conveyances, or segments of conveyances, (hereafter referred to collectively as “conveyances”), 

that are man-made, or predominantly channelized or predominantly physically altered; and

1. Are primarily used for water management purposes, such as flood protection, stormwater 

management, irrigation, or water supply; and

2. Have marginal or poor stream habitat or habitat components, such as a lack of habitat or substrate 

that is biologically limited, because the conveyance has cross sections that are predominantly 

trapezoidal, has armored banks, or is maintained primarily for water conveyance.

The phrase “primarily used for” in the definition of stream does not modify the definition of “designated 

use” in Rule 62-302.200, F.A.C. The designated use continues to be defined by the classification system 

in Rule 62-302.400, F.A.C. 

The following information will be used in identifying segments meeting the requirements in Rule 62-

302.200(36)(b):
56

DELINEATION

Only those sections that meet the requirements in Rule 62-302.200(36)(b), F.A.C., are eligible to retain 

the narrative nutrient criteria. A map of the applicable areas for review must clearly delineate the 

upstream and downstream extent of the artificial conveyance. 

PRIMARY WATER MANAGEMENT PURPOSE

Information must show that the current purpose of the man-made or physically altered conveyance is 

primarily water management such as flood protection, stormwater management, irrigation, or water 

supply. Relevant documentation can include photographic evidence, funding authorizations, 

operational protocols, local agreements, permits, memoranda of understanding, contracts, or other 

records that indicate how the conveyance is operated and maintained, and must verify that the design 

or maintenance of the conveyance allows the conveyance to currently function in a manner consistent 

with the primary water management purpose. 

The phrase “primarily used for water management purposes” in Rule 62-302.200(36)(b)1., F.A.C., does 

not include use for navigation or boat access to an adjacent waterbody, or frequent recreational 

activities. The purpose of the design of the conveyance in conjunction with the purpose of any 

subsequent alterations or maintenance is evaluated to help differentiate whether its primary function is 

navigation, boat access to adjacent waterbodies, or frequent recreational activities; versus flood 

protection, stormwater management, irrigation, or water supply. If available information provided by 

the public, in response to public notice and request for information, or otherwise known by the 

Department, demonstrates that the segment is commonly used for navigation, boat access, or other 

frequent recreational activities such as swimming or boating, then the primary purpose is not water 

management and the department will apply the nutrient standards in Rule 62-302.531(2) F.A.C. 

Freshwater finger canals dug during the construction of neighborhoods designed to create homes with 

boat access to waterbodies are an example of a navigation or access as a primary purpose. 

PHYSICAL ALTERATION THAT LIMITS HABITAT

The definition at Rule 62-302.200(36)(b)2., F.A.C., outlines that the conveyance must have marginal or 

poor stream habitat or habitat components that limit biological function because the conveyance has 

cross sections that are predominantly trapezoidal, has armored banks, or is maintained primarily for 

water conveyance. Photographic evidence of these limitations can demonstrate the habitat condition of 

the conveyance. Also, Standard Operating Procedures for conducting stream Habitat Assessments have 

been adopted by the Department in DEP SOP FT 3000. In order to qualify under Rule 62-

302.200(36)(b)2., F.A.C., the overall Habitat Assessment score must score either marginal or poor. 

The Habitat Assessment procedures include long-established criteria that can be used to demonstrate 

physical alterations in a system, and can provide information verifying that ongoing maintenance 

activities are associated with perpetuating those physical alterations. The lack of substrate and degree 

of artificial channelization are part of the definition and components of the Habitat Assessment scoring 

system, and a Habitat Assessment score must be completed by an individual with demonstrated 

proficiency (as per DEP SOP FT 3000) to indicate that the definition related to the segment’s 
57

modification is met. If there are different segments within the conveyance that exhibit different 

features, a Habitat Assessment is needed for each segment. The Department will conduct a Habitat 

Assessment if one was not previously conducted. 

To ensure adequate water volume delivery, routine maintenance activities associated with conveyances 

used for water management purposes often involve removal of aquatic substrate (e.g., woody debris, 

aquatic and wetland vegetation), dredging of sediments, and/or removal of riparian trees. If the 

Substrate Diversity and Availability and Artificial Channelization metrics in the Habitat Assessment score 

in the Poor category, then one can conclude that the conveyance is predominantly altered and is being 

maintained in a manner to serve the primary purpose for water management. The overall habitat 

assessment may not rank as Poor due to other factors, but a primary factor being considered in the 

definition is the alteration and the maintenance of the conveyance. If the Substrate Diversity and 

Availability or Artificial Channelization scores are currently in the marginal range due to lack of 

maintenance of the conveyance at the time the assessment was completed, the Department will 

evaluate whether there is a maintenance program with a schedule to demonstrate that the conveyance 

is still being maintained for its primary water management purpose. If the overall Habitat Assessment 

score is other than poor or marginal, the conveyances would not meet the definition.
58

Appendix A. Minimally Disturbed and Healthy Streams

Table A-1. List of healthy streams (passing SCI) used to inform RPS 

expectations.

STORET ID Station Description RPS Average

Percent 4 to 6 

Scores

Mean SCI

2007 

Score

SCI 

2007 

(n)

3497 Fisheating Creek @ Cr 27 0.0% 54 1

3509 ANCLOTE RIVER MOUTH AT S.R. 54 0.0% 47 1

3513 Withlacoochee River @ Stokes Ferry 40.4% 43 3

3531 S321 Econfina Creek 0.0% 73 1

3535 SUW010 Suwannee River 83.8% 61 1

3536 S418 Alaqua Creek 4.0% 90 1

3542 S250 Perdido River 9.1% 57 1

3545 S360 Blackwater River @ Hwy 4 4.0% 58 2

3546 S365 Yellow River @ Hwy 2 0.0% 79 1

3549 S377 Escambia River @ HWY 4 Bridge 0.0% 51 1

3554 FLO 57 162 0 Alafia River 28.8% 70 2

3555 Little Manatee River at HWY 301 2.5% 63 2

3569 Little Econlockhatchee River 5.1% 46 1

14264 SJB-LR-1006 BLACK CREEK 2.0% 73 1

21179 Spruce Creek 0.0% 45 1

21200 Rice Creek at SR100 4.0% 69 1

21201 Moultrie Creek 11.1% 63 1

21202 Orange Creek 1.0% 73 2

21460 Wrights Creek at CR 177A 4.0% 76 1

21461 BIG COLDWATER CR @ CR 191 1.0% 76 1

36366 Z2-LR-3010 Suwannee River 0.0% 57 1

36631 Z3-SS-3009 unnamed small stream 1.0% 83 1

36634 Z3-SS-3014 Trout River 2.0% 57 2

36636 Z3-SS-3038 Two mile Creek 1.0% 43 2

36639 Z2-SS-3003 Roaring Creek 0.0% 46 1

36641 Z2-SS-3016 unnamed small stream 31.8% 73 2

36642 Z2-SS-3030 unnamed small stream 0.0% 51 2

36646 Z2-SS-3068 unnamed small stream 1.0% 79 2

36648 Z2-SS-3075 unnamed small stream 0.0% 66 2

36998 Z4-LR-3004 Alafia River 21.7% 41 2

37003 Z4-LR-3022 Peace River 7.1% 48 2

37006 Z4-LR-3032 Anclote River 27.3% 43 2

37108 Z5-LR-3012 Lake Marion Creek 0.0% 45 1

37111 Z5-LR-3016 Boggy Creek 38.4% 47 2
59

STORET ID Station Description RPS Average

Percent 4 to 6 

Scores

Mean SCI

2007 

Score

SCI 

2007 

(n)

37506 Z1-LR-3008 Big Water Coldwater 0.0% 82 2

37508 Z1-LR-3011 Holmes Creek 7.6% 64 2

37539 Z1-SS-3006 Alaqua Creek 0.5% 90 2

37540 Z1-SS-3007 Williams Creek 0.0% 67 2

37542 Z1-SS-3010 unnamed stream 2.5% 62 2

37543 Z1-SS-3012 unnamed stream 0.0% 60 2

37544 Z1-SS-3013 unnamed stream 0.0% 72 2

37545 Z1-SS-3022 titi creek 1.5% 76 2

37546 Z1-SS-3025 Alaqua Creek 1.0% 79 2

37547 Z1-SS-3026 Horsehead Creek 0.0% 46 1

37548 Z1-SS-3027 unnamed stream 4.0% 59 2

38195 Z3-SS-3049 South prong St. Mary's River 6.1% 93 1

38441 Z2-LR-4004 Withlacoochee River 0.0% 52 2

38442 Z2-LR-4005 Suwannee River 0.0% 50 2

38444 Z2-LR-4008 Aucilla River 0.0% 49 2

38445 Z2-LR-4009 Suwannee River 0.0% 41 2

38448 Z2-LR-4012 Aucilla River 11.1% 55 2

38450 Z4-LR-4002 Peace River 0.0% 52 2

38451 Z4-LR-4003 Braden River 8.1% 51 2

38453 Z4-LR-4005 Pithlachascottee River 0.0% 74 2

38454 Z4-LR-4006 Horse Creek 16.2% 58 2

38455 Z4-LR-4009 Withlacoochee River 24.2% 42 1

38458 Z4-LR-4012 N. Prong Alafia River 1.0% 62 2

38479 Z1-LR-4001 Ochlockonee River 0.5% 45 2

38480 Z1-LR-4002 Chipola River 0.0% 59 2

38481 Z1-LR-4003 Choctawhatchee River 4.0% 66 2

38482 Z1-LR-4004 East Fork Creek 20.2% 64 2

38484 Z1-LR-4006 Ochlockonee River 0.0% 58 2

38485 Z1-LR-4007 Chipola River 16.2% 58 2

38486 Z1-LR-4008 Yellow River 1.0% 66 2

38488 Z1-LR-4011 Yellow River 0.0% 67 2

38502 Z5-LR-4004 Boggy Creek 0.0% 57 1

38504 Z5-LR-4009 Fisheating Creek 35.4% 60 1

38520 Z3-SS-4008 Gee Creek 0.5% 48 2

38521 Z3-SS-4010 Simms Creek 0.0% 90 1

38525 Z3-SS-4023 Two Mile Creek 0.5% 47 2

38529 Z3-SS-4051 unnamed stream 2.0% 77 1
60

STORET ID Station Description RPS Average

Percent 4 to 6 

Scores

Mean SCI

2007 

Score

SCI 

2007 

(n)

38559 Z1-SS-4003 unknown stream 4.5% 60 2

38560 Z1-SS-4006 unknown stream 0.0% 68 2

38561 Z1-SS-4009 unknown stream 0.0% 77 2

38562 Z1-SS-4013 unknown stream 0.0% 93 2

38563 Z1-SS-4015 unknown stream 0.0% 47 1

38564 Z1-SS-4017 unknown stream 5.1% 62 2

38565 Z1-SS-4018 unknown stream 0.0% 81 2

38566 Z1-SS-4022 unknown stream 0.0% 68 2

38568 Z1-SS-4027 unknown stream 0.0% 70 2

38570 Z5-SS-4008 Telegraph Creek 0.0% 54 1

38571 Z5-SS-4022 unnamed small stream 0.0% 58 1

38572 Z5-SS-4034 Gore Branch 7.1% 44 1

38573 Z5-SS-4041 Arbuckle Creek 0.0% 45 1

38574 Z5-SS-4056 Bedman Creek 0.0% 51 1

38580 Z6-SS-4010 Mosquito Creek 2.0% 57 1

38603 Z2-SS-4029 Water Oak Creek 0.0% 64 1

38605 Z2-SS-4033 unnamed Stream 0.0% 67 1

38607 Z2-SS-4040 Mitchell Creek 0.0% 62 1

38609 Z4-SS-4002 Oak Creek 33.3% 52 1

38610 Z4-SS-4004 Gator Creek 0.0% 52 2

38612 Z4-SS-4020 Blackwater Creek 14.1% 64 1

38614 Z4-SS-4024 unnamed stream 33.3% 59 1

19010006 ST MARYS RIVER AT SR #2 0.0% 103 1

19010041 St Mary's River at CR 125 0.0% 78 1

19010076 Calkins Creek at Turner Cemetery Road 0.0% 76 2

19020052 Alligator Ck east of US301 & SR115 0.0% 63 1

20010204 Lt Wekiva R, 100 yd dwnstr of Altamonte 

Spgs STP

38.9% 53 2

20010333 Robert's brnch @ curryville rd 20.7% 65 2

20010431 WEKIVA R. UPSTRM OF ROCK SPRINGS 65.7% 56 2

20010438 WEKIVA R UPSTR OF BLACKWATER CR 49.5% 82 1

20020317 SILVER RUN AT CONFLUENCE WITH BOAT 

RAMP CANAL

33.3% 57 1

20030388 PETERS CREEK #2 CULVERT SR 315 0.0% 86 1

20030481 South Fork Black Creek @ SR 21 0.0% 83 1

20030920 Mormon Branch upstream of SR 19 in 

Ocala NF

25.3% 69 3

21010008 ALAPAHA RIVER 1 SR 150 HAMILTON 9.1% 59 1
61

STORET ID Station Description RPS Average

Percent 4 to 6 

Scores

Mean SCI

2007 

Score

SCI 

2007 

(n)

21010018 Falling Creek @ CR 131, above falls 

Suwannee R.

0.0% 54 2

21010033 Little Creek @ US 441 0.0% 89 1

21010040 Suwannee River above White Springs 

WWTP

3.0% 69 1

21010054 PCS Phosphate FYI5, test site 1 0.0% 52 1

21020001 SUWANNEE R U/S FR CONFL SWIFT CR 0.5% 58 2

21020062 SUWANNEE R ~ 150M D/S SWIFT CREEK 0.0% 52 2

21020098 Bethel Creek S Frk at SR 53 0.0% 76 1

21020124 LITTLE CR. ~ 300 M UPSTREAM 

SUWANNEE R

0.0% 73 2

21030011 SANTA FE R #6 AT SR 47 90.9% 49 1

21030049 NEW RIVER AT SR 18 0.0% 76 1

22020093 Quincy Creek above SR267 bridge 0.0% 57 1

22040004 AUCILLA R AT US 90 0.0% 61 1

22040009 WASCISSA R #1 AT BIG BLUE SPRING 65.7% 40 1

22040041 Wacissa River Bio Site 2 4.0% 65 1

22050083 Steinhatchee @ Canal Road 34.3% 52 2

23010444 WITHLACOOCHEE R@CANOE LAUNCH IN 

LACOOCHEE PARK 

29.3% 52 1

23010464 Withlacoochee R @ county park off 

Auton Rd (TP3)

5.6% 43 2

23020001 Waccasassa R at US 19 20.2% 66 2

23020020 Waccasassa River @ WMA 0.0% 80 2

23020021 Waccasassa River @ OB Road #3 0.0% 82 2

24010002 Manatee R 20 m below SR64 bridge (TP1) 41.4% 64 1

24010063 Gamble Crk, East on Golf Course Rd. 2.0% 43 2

24020080 Alafia Rv- TP 80 8.6% 55 2

24020361 Alafia River S Prong @ Bethlehem Road 0.0% 67 1

24030044 Hillsborough R in Hills River State Park 

(TP5)

3.5% 66 2

24030081 Itchepackasassa Ck @ CR 582 0.0% 58 2

24040072 Anclote River @ Green Brooks Estates 0.0% 45 2

25020013 BOWLEGS CREEK MT PISGAH RD 0.0% 60 1

25020015 PEACE R AT SR64 ZOLFO SPRINGS 18.2% 43 1

25020111 Horse Creek @ SR 72 Bridge 41.9% 70 2

25020291 Troublesome Creek at Dansby Road 0.0% 59 1

25020292 Joshua Creek at airport road 37.4% 47 1

25020293 Peace River @ 664A 16.2% 48 1
62

STORET ID Station Description RPS Average

Percent 4 to 6 

Scores

Mean SCI

2007 

Score

SCI 

2007 

(n)

25020294 Charlie creek at Sweetwater Road 6.1% 61 1

25020295 Paynes creek at State Park 12.1% 63 2

25020296 Paynes Creek at Hobbs Road 0.0% 61 1

25020300 Hawthorne Creek at Reynolds 12.1% 59 1

25020423 HORSE CREEK AT SR70 56.6% 57 1

25020427 HORSE CRK AT SR 665 BRDG 8.1% 48 1

25020548 Little Charley Bowlegs Ck, Highlands 

Hammock SP

0.0% 46 1

25020550 HOG BAY at CR 763 (S of Arcadia) 12.1% 53 1

25020553 Myrtle Slough- East Brch Punta G. Ref site 0.0% 56 2

25022977 Charlie Cr upstream of US27. Horse Cr 

short term study

19.2% 71 1

25022983 Horse Cr,located on Royal Park Estates, 

south of US72. Horse Cr short term study

18.2% 60 2

25030009 MYAKKA RIVER ABOVE SR 70 BRIDGE 0.0% 59 1

26010430 Fort Drum Creek @ US441 0.5% 49 2

26010614 Carter Creek @ Riverdale Rd 0.0% 72 1

27010050 Moses Creek @ US 1 0.0% 60 1

27010070 STEVENS BR OFF CR 204 SOUTH OF 

PELICER CEMETARY

13.1% 76 1

27010337 Horse Creek at Croton Road, Eau Gallie 4.5% 40 2

27010579 Tomoka River @ Eleventh Street Bridge 6.1% 56 3

28010081 LOX R AT TURNPIKE. W OF JUPITER 0.0% 44 2

28020147 HICKEY CREEK 1 MI SOUTH OF SR80 0.0% 52 2

28020155 Bedman Creek at Betts house 0.0% 46 2

31020012 CHIPOLA R HWY 274 CROSS CHIPOLA 0.0% 42 1

32008102 SFTRIB_ARSP 0.5% 53 2

32010066 SHAW STILL BRANCH E COLLEGE DR. 

TALL. BASE LINE

18.2% 45 2

32010121 Mill Creek Eglin AFB Golf Course below 

17th HoleJAX GRD stream restoration 

proj.

3.0% 59 2

32010268 Turkey Creek (Bolton) East of Niceville 55.1% 55 2

32020258 Holmes Creek at 276A 0.0% 56 1

32030023 ECONFINA CREEK AT SCOTT RD 1.0% 82 1

33010112 Coffee Cr 1800Ft N of Stiller Lake Rd 0.0% 63 1

33030003 BIG COLDWATER CR E FORK HWY 4 2.0% 72 1

283430821152 Little Withlacoochee River at River 

Junction recreation area

0.0% 79 1
63

STORET ID Station Description RPS Average

Percent 4 to 6 

Scores

Mean SCI

2007 

Score

SCI 

2007 

(n)

27051558216422 Deer Prairie Slough, on land acquired by 

Sarasota County

2.0% 74 1

27422738148581 Whidden Cr at Unnamed Rd off of Rt 

17/35

1.0% 52 1

27514908208136 N.Prong Alafia at Alderman Ford Park 0.0% 77 1

28152268239035 Pithlachascotee River at Starkey Blvd, 

upstream of bridge

0.0% 48 2

273116508208152 East Fork Manatee R. S of US62 on Duette 

Park. Myakka DOSSAC study

0.0% 71 1

28020299FTM BEE BRANCH SITE 2 0.0% 49 1

3598-B Sampson River 1.0% 65 1

BAK208GS St. Mary's River - BAK208GS 0.0% 50 1

CHA627GS Alligator Creek - CHA627GS 0.0% 45 2

CLA243LV Ates Creek - CLA243LV 0.0% 91 1

CLA246GS Peters Creek - CLA246GS 0.0% 83 2

CLA254LR Black Creek - CLA254LR 0.0% 91 1

DEP010C1 Deep Creek @441 0.0% 80 1

FAL020C1 Falling Creek @C-131 0.0% 55 1

GAD106GS Yon Creek - GAD106GS 0.0% 81 1

GLA630GS Cypress Branch - GLA630GS 0.0% 63 1

HAR610GS Oak Creek - HAR610GS 1.3% 57 3

LAF176GS Bethel Creek - LAF176GS 0.0% 61 1

LIB104LV Mule Creek - LIB104LV 0.0% 67 1

LOCBCC Little Orange Creek below Cabbage 0.0% 89 1

MPS St. Mary's River middle prong 0.0% 71 1

MRN504LR Rainbow River - MRN504LR 42.4% 62 2

NUTREF001 Telogia Creek at CR 1641 0.0% 78 1

OSC686LV Crabgrass Creek 0.0% 62 1

PUT308GS Little Orange Creek - PUT308GS 0.0% 75 1

ROB01C1 Robinson Branch @C-246 0.0% 81 1

S231 Attapulgus Creek @ 159 0.0% 65 1

S232 Swamp Creek @ 159 0.0% 51 1

SFR030C1 Santa Fe River @ 18 Worthington Springs 0.0% 64 1

SPRINGS006 Wakiwa (Wekiva) R. ab. Rock Spgs run 45.5% 41 1

SSR Silver River above confluence of 

Oklawaha River

32.3% 46 1

UNI234LV Olustee Creek - UNI234LV 0.0% 44 1

WAK168LR St. Marks River - WAK168LR 15.2% 45 1
64

Table A-2. List of benchmark streams used to establish RPS and LVS 

expectations.

STORET ID Station Description WBID RPS Average

Percent 4 to 6 

Scores

3531 S321 Econfina Creek 553 0.0%

3545 S360 Blackwater River @ Hwy 4 24C 4.0%

3546 S365 Yellow River @ Hwy 2 30 0.0%

3549 S377 Escambia River @ HWY 4 Bridge 10C 0.0%

3554 FLO 57 162 0 Alafia River 1621B 28.8%

21201 Moultrie Creek 2493 11.1%

38482 Z1-LR-4004 East Fork Creek 18A 20.2%

38486 Z1-LR-4008 Yellow River 30B 1.0%

38570 Z5-SS-4008 Telegraph Creek 3236A 0.0%

19010006 ST MARYS RIVER AT SR #2 2097K 0.0%

19010041 St Mary's River at CR 125 2211 0.0%

19010076 Calkins Creek at Turner Cemetary Road 2264 0.0%

20030388 PETERS CREEK #2 CULVERT SR 315 2444 0.0%

20030481 South Fork Black Creek @ SR 21 2415E 0.0%

20030920 Mormon Branch upstream of SR 19 in Ocala NF 2905 25.3%

21010008 ALAPAHA RIVER 1 SR 150 HAMILTON 3324 9.1%

22020093 Quincy Creek above SR267 bridge 1303 0.0%

22040009 WASCISSA R #1 AT BIG BLUE SPRING 3424 65.7%

22040041 Wacissa River Bio Site 2 3424 4.0%

22050083 Steinhatchee @ Canal Road 3573A 34.3%

24010002 Manatee R 20 m below SR64 bridge (TP1) 1807C 41.4%

24030044 Hillsborough R in Hills River State Park (TP5) 1443D 3.5%

25030009 MYAKKA RIVER ABOVE SR 70 BRIDGE 1877A 0.0%

26010430 Fort Drum Creek @ US441 3164 0.5%

32030023 ECONFINA CREEK AT SCOTT RD 553 1.0%

33030003 BIG COLDWATER CR E FORK HWY 4 18A 2.0%

27051558216422 Deer Prairie Slough, on land acquired by Sarasota 

County

1978 2.0%

28020299FTM BEE BRANCH SITE 2 3235E 0.0%

BAK208GS St. Mary's River - BAK208GS 2097K 0.0%

CLA243LV Ates Creek - CLA243LV 2498 0.0%

CLA246GS Peters Creek - CLA246GS 2444 0.0%

DEP010C1 Deep Creek @441 3388 0.0%

GLA630GS Cypress Branch - GLA630GS 3235G 0.0%

HAR610GS Oak Creek - HAR610GS 1897 1.3%

LIB104LV Mule Creek - LIB104LV 684 0.0%
65

STORET ID Station Description WBID RPS Average

Percent 4 to 6 

Scores

LOCBCC Little Orange Creek below Cabbage 2713 0.0%

MPS St. Mary's River middle prong 2211 0.0%

NUTREF001 Telogia Creek at CR 1641 1300 0.0%

PUT308GS Little Orange Creek - PUT308GS 2713 0.0%

ROB01C1 Robinson Branch @C-246 3448 0.0%

SFR030C1 Santa Fe River @ 18 Worthington Springs 3605D 0.0%

Table A-3. List of healthy streams (passing SCI) used to inform stream 

chlorophyll a expectations.

WBID Basin Year Geometric 

mean Chl-a 

(μg/L)

Mean SCI 

2007

4 BRUSHY CREEK 2006 2.2 64

4 BRUSHY CREEK 2007 2.1 64

4 BRUSHY CREEK 2008 1.3 64

4 BRUSHY CREEK 2009 1.1 64

4 BRUSHY CREEK 2010 1.1 64

18 BIG COLDWATER CREEK 2006 3.1 76

18 BIG COLDWATER CREEK 2007 3.2 76

18 BIG COLDWATER CREEK 2008 1.0 76

18 BIG COLDWATER CREEK 2009 1.0 76

18 BIG COLDWATER CREEK 2010 1.0 76

18 BIG COLDWATER CREEK 2011 1.0 76

19 BIG JUNIPER CREEK 2007 3.8 70

24 BLACKWATER RIVER 2009 1.0 68

30 YELLOW RIVER 2006 2.1 70

30 YELLOW RIVER 2007 2.0 70

30 YELLOW RIVER 2008 1.3 70

30 YELLOW RIVER 2009 1.6 70

30 YELLOW RIVER 2010 1.3 70

35 POND CREEK 2007 3.6 78

36 BRAY MILL CREEK 2009 1.0 48

52 COWARTS CREEK 2006 1.0 59

52 COWARTS CREEK 2007 1.0 59

52 COWARTS CREEK 2008 1.0 59

52 COWARTS CREEK 2009 1.3 59

52 COWARTS CREEK 2010 1.2 59
66

WBID Basin Year Geometric 

mean Chl-a 

(μg/L)

Mean SCI 

2007

54 WRIGHTS CREEK 2006 1.0 67

54 WRIGHTS CREEK 2007 1.0 67

54 WRIGHTS CREEK 2008 1.0 67

54 WRIGHTS CREEK 2009 1.0 67

54 WRIGHTS CREEK 2010 1.0 67

59 HOLMES CREEK 2006 1.0 59

59 HOLMES CREEK 2009 1.0 59

72 PERDIDO RIVER (MIDDLE B) 2006 1.8 59

72 PERDIDO RIVER (MIDDLE B) 2007 2.2 59

72 PERDIDO RIVER (MIDDLE B) 2008 1.1 59

72 PERDIDO RIVER (MIDDLE B) 2009 1.1 59

72 PERDIDO RIVER (MIDDLE B) 2010 1.2 59

72 PERDIDO RIVER (MIDDLE B) 2011 1.1 59

87 LITTLE PINE BARREN CREEK 2009 3.2 71

88 MARE CREEK 2009 1.1 73

107 MURDER CREEK 2009 1.2 64

127 MANNING CREEK 2009 1.1 67

149 MCDAVID CREEK 2006 5.6 73

149 MCDAVID CREEK 2010 1.4 73

176 POND CREEK 2007 4.7 81

291 JACKS BRANCH 2010 1.8 42

316 CROOKED CREEK 2009 1.0 44

351 ALAQUA CREEK 2006 1.1 82

351 ALAQUA CREEK 2007 1.0 82

351 ALAQUA CREEK 2008 1.0 82

351 ALAQUA CREEK 2009 1.1 82

351 ALAQUA CREEK 2010 1.0 82

553 ECONFINA CREEK 2006 1.0 75

553 ECONFINA CREEK 2007 1.0 75

553 ECONFINA CREEK 2008 1.0 75

553 ECONFINA CREEK 2009 1.0 75

553 ECONFINA CREEK 2010 1.0 75

684 MULE CREEK 2006 1.9 73

716 CANEY BRANCH 2006 1.9 49

757 BEAR CREEK 2006 2.6 72

896 POLK CREEK 2010 1.0 55

921 HARVEY CREEK 2006 1.9 61
67

WBID Basin Year Geometric 

mean Chl-a 

(μg/L)

Mean SCI 

2007

921 HARVEY CREEK 2010 1.0 61

998 SOPCHOPPY RIVER 2006 2.1 49

1024 BLACK CREEK 2010 1.0 85

1028 MCBRIDE SLOUGH 2006 1.7 57

1300 TELOGIA CREEK 2006 2.1 70

1300 TELOGIA CREEK 2007 1.1 70

1300 TELOGIA CREEK 2008 1.6 70

1300 TELOGIA CREEK 2009 1.0 70

1300 TELOGIA CREEK 2010 1.0 70

1381 LITTLE WITHLACOOCHEE 2008 3.5 56

1381 LITTLE WITHLACOOCHEE 2009 1.8 56

1409 PITHLACHASCOTEE RIVER 2008 4.0 58

1409 PITHLACHASCOTEE RIVER 2010 1.2 58

1431 GATOR CREEK 2008 4.5 54

1431 GATOR CREEK 2009 1.7 54

1431 GATOR CREEK 2010 1.9 54

1436 HORSE (HORSESHOE) CREEK 2009 2.0 60

1436 HORSE (HORSESHOE) CREEK 2010 3.3 60

1482 BLACKWATER CREEK 2010 9.4 64

1583 POLEY CREEK 2008 3.5 44

1639 THIRTYMILE CREEK 2006 1.5 53

1639 THIRTYMILE CREEK 2007 1.3 53

1639 THIRTYMILE CREEK 2008 2.4 53

1688 LITTLE BULLFROG CREEK 2006 1.5 42

1688 LITTLE BULLFROG CREEK 2007 1.3 42

1688 LITTLE BULLFROG CREEK 2009 1.8 42

1790 LITTLE MANATEE RIVER (SOUTH 

FORK)

2009 1.1 51

1811 MANATEE RIVER (EAST FORK) 2007 1.7 64

1813 CARTER CREEK 2006 8.7 65

1978 DEER PRAIRIE CREEK 2008 2.3 67

1978 DEER PRAIRIE CREEK 2010 1.2 67

1997 HAWTHORNE CREEK 2008 1.9 59

2001 HOG BAY 2007 1.8 50

2001 HOG BAY 2008 2.6 50

2074 ALLIGATOR CREEK 2007 1.4 44

2074 ALLIGATOR CREEK 2008 4.0 44

2196 DEEP CREEK 2008 1.4 49
68

WBID Basin Year Geometric 

mean Chl-a 

(μg/L)

Mean SCI 

2007

2211 MIDDLE PRONG ST MARYS RIVER 2006 1.6 70

2211 MIDDLE PRONG ST MARYS RIVER 2007 1.3 70

2211 MIDDLE PRONG ST MARYS RIVER 2008 1.0 70

2211 MIDDLE PRONG ST MARYS RIVER 2009 1.0 70

2264 CALKINS CREEK 2008 2.6 76

2444 PETERS CREEK 2008 1.4 86

2444 PETERS CREEK 2009 1.5 86

2478 GREENS CREEK 2007 1.3 66

2493 MOULTRIE CREEK 2006 1.3 56

2493 MOULTRIE CREEK 2007 1.3 56

2493 MOULTRIE CREEK 2008 1.1 56

2493 MOULTRIE CREEK 2009 1.0 56

2493 MOULTRIE CREEK 2010 1.2 56

2634 TOMOKA RIVER 2006 1.1 47

2634 TOMOKA RIVER 2007 1.3 47

2634 TOMOKA RIVER 2008 4.2 47

2634 TOMOKA RIVER 2009 2.8 47

2634 TOMOKA RIVER 2010 2.0 47

2634 TOMOKA RIVER 2011 1.3 47

2641 UNNAMED BRANCH 2010 1.5 51

2646 LITTLE TOMOKA RIVER 2010 4.0 50

2673 UNNAMED DRAIN 2010 1.7 47

2675 SAND CREEK 2010 2.8 57

2679 UNNAMED DRAIN 2010 1.0 59

2695 LITTLE HATCHET CREEK 2006 2.2 56

2698 HOGTOWN CREEK 2006 1.3 49

2713 LITTLE ORANGE CREEK 2006 1.5 77

2730 DEEP CREEK RODMAN RESERVOIR 2011 1.1 60

2747 ORANGE CREEK 2006 1.2 78

2747 ORANGE CREEK 2007 1.1 78

2747 ORANGE CREEK 2008 1.0 78

2747 ORANGE CREEK 2009 1.1 78

2747 ORANGE CREEK 2010 1.0 78

2756 MILL CREEK 2010 1.2 65

2987 LITTLE WEKIVA RIVER 2006 2.7 56

2987 LITTLE WEKIVA RIVER 2007 3.9 56

2987 LITTLE WEKIVA RIVER 2009 3.4 56
69

WBID Basin Year Geometric 

mean Chl-a 

(μg/L)

Mean SCI 

2007

2987 LITTLE WEKIVA RIVER 2010 1.5 56

2991 ECONLOCKHATCHEE RIVER 2006 1.1 62

2991 ECONLOCKHATCHEE RIVER 2007 1.2 62

2991 ECONLOCKHATCHEE RIVER 2008 1.1 62

2997 HOWELL CREEK BELOW LAKE 

HOWELL

2009 6.2 55

2999 BEAR CREEK 2009 1.8 52

3073 CRABGRASS CREEK 2007 1.5 62

3081 HORSE CREEK 2006 2.4 42

3081 HORSE CREEK 2007 2.5 42

3081 HORSE CREEK 2008 3.1 42

3164 FORT DRUM CREEK 2008 17.2 48

3324 ALAPAHA RIVER 2006 1.2 54

3324 ALAPAHA RIVER 2007 1.6 54

3324 ALAPAHA RIVER 2008 1.6 54

3324 ALAPAHA RIVER 2009 1.1 54

3324 ALAPAHA RIVER 2010 1.3 54

3325 ALLIGATOR CREEK 2006 1.3 69

3330 LITTLE ALAPAHA RIVER 2006 1.3 44

3351 ROCKY CREEK NEAR BENTON 2006 1.1 59

3351 ROCKY CREEK NEAR BENTON 2007 2.3 59

3351 ROCKY CREEK NEAR BENTON 2010 1.0 59

3388 DEEP CREEK 2006 1.5 78

3401 CAMP BRANCH 2010 3.2 55

3402 ECONFINA RIVER 2006 1.1 51

3402 ECONFINA RIVER 2007 2.4 51

3402 ECONFINA RIVER 2008 1.4 51

3402 ECONFINA RIVER 2009 1.0 51

3402 ECONFINA RIVER 2010 1.0 51

3422 SUWANNEE RIVER (LOWER 

SEGMENT)

2006 1.2 48

3448 ROBINSON CREEK 2006 1.4 81

3480 BETHEL CREEK 2006 1.0 54

3506 NEW RIVER 2010 2.2 73

3598 SAMPSON RIVER 2010 1.7 69

3649 COW CREEK 2006 2.6 69

3649 COW CREEK 2007 1.9 69

3649 COW CREEK 2010 1.4 69
70

WBID Basin Year Geometric 

mean Chl-a 

(μg/L)

Mean SCI 

2007

3699 WACCASASSA RIVER 2007 3.0 75

3699 WACCASASSA RIVER 2008 2.6 75

3699 WACCASASSA RIVER 2009 2.1 75

3731 WEKIVA RIVER 2009 1.0 71

1320B RAINBOW SPRINGS GROUP RUN 2006 1.0 58

1320B RAINBOW SPRINGS GROUP RUN 2007 1.0 58

1320B RAINBOW SPRINGS GROUP RUN 2008 1.0 58

1320B RAINBOW SPRINGS GROUP RUN 2009 1.0 58

1320B RAINBOW SPRINGS GROUP RUN 2010 1.0 58

1351A OUTLET RIVER 2010 11.8 43

1443D HILLSBOROUGH RIVER 2008 2.2 61

1443D HILLSBOROUGH RIVER 2009 1.2 61

1495A ITCHEPACKESASSA CREEK 2007 1.9 49

1495A ITCHEPACKESASSA CREEK 2008 9.8 49

1495B ITCHEPACKESASSA CREEK 2008 3.1 58

1573D WEOHYAKAPKA CREEK 2010 6.2 56

1592C MUSTANG RANCH CREEK 2010 2.6 59

160B SHOAL RIVER 2007 2.9 84

1621A ALAFIA RIVER ABOVE 

HILLSBOROUGH BAY

2009 3.5 41

1621B ALAFIA RIVER ABOVE FLINT HAWK 2006 2.1 57

1621B ALAFIA RIVER ABOVE FLINT HAWK 2007 2.0 57

1621B ALAFIA RIVER ABOVE FLINT HAWK 2008 1.7 57

1621B ALAFIA RIVER ABOVE FLINT HAWK 2009 3.2 57

1621B ALAFIA RIVER ABOVE FLINT HAWK 2010 3.5 57

1621D ALAFIA RIVER (NORTH PRONG) 

LOWER SEGMENT

2008 1.6 63

1621D ALAFIA RIVER (NORTH PRONG) 

LOWER SEGMENT

2009 1.6 63

1685B LIVINGSTON CREEK 2006 19.0 65

1685B LIVINGSTON CREEK 2007 6.4 65

1685B LIVINGSTON CREEK 2008 11.8 65

1685B LIVINGSTON CREEK 2009 4.4 65

1685B LIVINGSTON CREEK 2010 3.3 65

1742B LITTLE MANATEE RIVER (NORTH 

FORK)

2006 1.5 46

1757A PAYNE CREEK (LOWER SEGMENT) 2008 1.1 59

1757A PAYNE CREEK (LOWER SEGMENT) 2009 2.8 59
71

WBID Basin Year Geometric 

mean Chl-a 

(μg/L)

Mean SCI 

2007

1757B PAYNE CREEK (UPPER SEGMENT) 2007 1.3 62

1757B PAYNE CREEK (UPPER SEGMENT) 2008 1.1 62

1787B HORSE CREEK ABOVE BUSHY CREEK 2007 1.0 66

1807C MANATEE RIVER 2007 1.4 72

1877A MYAKKA RIVER (UPPER SEGMENT) 2006 1.2 43

1877A MYAKKA RIVER (UPPER SEGMENT) 2007 1.4 43

1877A MYAKKA RIVER (UPPER SEGMENT) 2008 1.5 43

1877A MYAKKA RIVER (UPPER SEGMENT) 2010 1.8 43

18A EAST FORK 2007 3.0 70

18A EAST FORK 2009 1.1 70

2097H ST MARYS RIVER 2007 2.3 55

2097K ST MARYS RIVER (NORTH PRONG) 2006 1.2 57

2097K ST MARYS RIVER (NORTH PRONG) 2007 1.2 57

2097K ST MARYS RIVER (NORTH PRONG) 2008 1.3 57

2386A BLACK CREEK (NORTH FORK) 2006 1.7 56

2386A BLACK CREEK (NORTH FORK) 2007 1.4 56

2386A BLACK CREEK (NORTH FORK) 2008 1.1 56

2386A BLACK CREEK (NORTH FORK) 2009 1.3 56

2386A BLACK CREEK (NORTH FORK) 2010 1.4 56

2415C BLACK CREEK (SOUTH FORK) 2008 1.2 91

24D BLACKWATER RIVER 2007 1.6 65

2535B MOSES CREEK (FRESHWATER 

SEGMENT)

2008 1.2 63

2740C OCKLAWAHA RIVER ABOVE LAKE 

OCKLAWAHA

2006 1.5 63

2740C OCKLAWAHA RIVER ABOVE LAKE 

OCKLAWAHA

2007 1.6 63

2740C OCKLAWAHA RIVER ABOVE LAKE 

OCKLAWAHA

2008 1.2 63

2740C OCKLAWAHA RIVER ABOVE LAKE 

OCKLAWAHA

2009 1.2 63

2740C OCKLAWAHA RIVER ABOVE LAKE 

OCKLAWAHA

2010 1.4 63

2740C OCKLAWAHA RIVER ABOVE LAKE 

OCKLAWAHA

2011 1.2 63

2772D SILVER RIVER (LOWER) 2006 1.8 54

2772D SILVER RIVER (LOWER) 2007 1.1 54

2772D SILVER RIVER (LOWER) 2008 1.0 54

2772D SILVER RIVER (LOWER) 2009 1.1 54
72

WBID Basin Year Geometric 

mean Chl-a 

(μg/L)

Mean SCI 

2007

2929A BLACK WATER CREEK 2006 1.1 54

2929A BLACK WATER CREEK 2007 1.4 54

2929A BLACK WATER CREEK 2008 1.2 54

2929A BLACK WATER CREEK 2009 1.3 54

2929A BLACK WATER CREEK 2010 1.2 54

2987B LITTLE WEKIVA (WEST) 2008 5.8 46

2991A ECONLOCKHATCHEE RIVER 2007 1.6 50

2991A ECONLOCKHATCHEE RIVER 2009 1.0 50

2991A ECONLOCKHATCHEE RIVER 2010 1.1 50

30A YELLOW RIVER 2007 1.6 54

30A YELLOW RIVER 2008 1.2 54

3169A SHINGLE CREEK 2007 1.2 50

3169A SHINGLE CREEK 2008 1.1 50

3169A SHINGLE CREEK 2009 1.6 50

3170D2 BONNET CREEK SOUTH 2009 7.8 44

3224C CYPRESS CREEK 2011 2.3 44

3235E BEE BRANCH 2008 2.8 49

3235H HICKEY CREEK 2006 2.5 50

3235H HICKEY CREEK 2007 3.6 50

3235H HICKEY CREEK 2008 4.2 50

3235H HICKEY CREEK 2009 1.7 50

3235I BEDMAN CREEK 2006 1.7 49

3235I BEDMAN CREEK 2007 2.1 49

3235I BEDMAN CREEK 2008 1.6 49

3235I BEDMAN CREEK 2009 1.3 49

3235I BEDMAN CREEK 2010 1.1 49

3236A TELEGRAPH CREEK 2006 2.0 59

3236A TELEGRAPH CREEK 2007 2.0 59

3236A TELEGRAPH CREEK 2008 3.0 59

3236A TELEGRAPH CREEK 2009 2.9 59

3236A TELEGRAPH CREEK 2010 1.8 59

3240F DAUGHTREY CREEK 2006 2.0 55

3240F DAUGHTREY CREEK 2007 5.2 55

3240F DAUGHTREY CREEK 2008 4.1 55

3240F DAUGHTREY CREEK 2009 2.4 55

3240F DAUGHTREY CREEK 2010 2.4 55

3240F DAUGHTREY CREEK 2011 3.3 55
73

WBID Basin Year Geometric 

mean Chl-a 

(μg/L)

Mean SCI 

2007

3240K ORANGE RIVER 2006 2.0 41

3341A SUWANNEE RIVER (UPPER 

SEGMENT)

2008 1.7 58

3341C SUWANNEE RIVER (UPPER 

SEGMENT)

2006 1.3 48

3422P MEARSON SPRING 2006 1.5 54

3504A OLUSTEE CREEK 2006 2.2 53

3504A OLUSTEE CREEK 2007 5.0 53

3504A OLUSTEE CREEK 2010 1.2 53

3598C ALLIGATOR CREEK 2006 1.1 41

49F CHOCTAWHATCHEE RIVER 2006 1.2 57

49F CHOCTAWHATCHEE RIVER 2007 1.6 57

49F CHOCTAWHATCHEE RIVER 2008 1.5 57

49F CHOCTAWHATCHEE RIVER 2009 1.6 57

49F CHOCTAWHATCHEE RIVER 2010 2.2 57

72D PERDIDO RIVER (MIDDLE A) 2008 1.1 56

791L LAKE MICCOSUKEE OUTLET 2010 2.6 52

Table A-4. List of benchmark streams used to establish stream chlorophyll a 

expectations.

WBID Basin Year Geometric mean 

Chl-a (μg/L)

24 BLACKWATER RIVER 1998 5.0

24 BLACKWATER RIVER 2009 1.0

30 YELLOW RIVER 2000 1.2

30 YELLOW RIVER 2001 1.1

30 YELLOW RIVER 2002 1.0

30 YELLOW RIVER 2003 1.6

30 YELLOW RIVER 2004 1.9

30 YELLOW RIVER 2005 2.5

30 YELLOW RIVER 2006 2.1

30 YELLOW RIVER 2007 2.0

30 YELLOW RIVER 2008 1.3

30 YELLOW RIVER 2009 1.6

30 YELLOW RIVER 2010 1.3

30 YELLOW RIVER 2010 1.4
74

WBID Basin Year Geometric mean 

Chl-a (μg/L)

149 MCDAVID CREEK 2005 3.5

149 MCDAVID CREEK 2006 5.6

149 MCDAVID CREEK 2010 1.4

279 DRY CREEK 2005 1.2

279 DRY CREEK 2007 1.2

397 UNNAMED RUN 2005 2.2

504 CROOKED CREEK 2005 1.4

553 ECONFINA CREEK 2000 1.0

553 ECONFINA CREEK 2001 1.0

553 ECONFINA CREEK 2002 1.0

553 ECONFINA CREEK 2003 1.0

553 ECONFINA CREEK 2004 1.0

553 ECONFINA CREEK 2005 1.0

553 ECONFINA CREEK 2006 1.0

553 ECONFINA CREEK 2007 1.0

553 ECONFINA CREEK 2008 1.0

553 ECONFINA CREEK 2009 1.0

553 ECONFINA CREEK 2009 1.0

553 ECONFINA CREEK 2010 1.0

569 TENMILE CREEK 2002 1.1

569 TENMILE CREEK 2007 1.1

679 BLACK CREEK 2008 1.7

684 MULE CREEK 2005 1.2

684 MULE CREEK 2006 1.9

718 FOURMILE CREEK 2002 1.0

718 FOURMILE CREEK 2007 1.1

749 JUNIPER CREEK 2007 1.4

889 MOORE LAKE DRAIN 2008 1.6

889 MOORE LAKE DRAIN 2010 1.0

998 SOPCHOPPY RIVER 2004 1.0

998 SOPCHOPPY RIVER 2005 1.2

998 SOPCHOPPY RIVER 2006 2.1

1240 FORT GADSDEN CREEK 2007 2.7

1300 TELOGIA CREEK 1999 1.0

1300 TELOGIA CREEK 2000 1.6

1300 TELOGIA CREEK 2001 1.1

1300 TELOGIA CREEK 2002 1.0

1300 TELOGIA CREEK 2003 1.0
75

WBID Basin Year Geometric mean 

Chl-a (μg/L)

1300 TELOGIA CREEK 2004 1.1

1300 TELOGIA CREEK 2005 1.1

1300 TELOGIA CREEK 2006 2.1

1300 TELOGIA CREEK 2007 1.1

1300 TELOGIA CREEK 2008 1.6

1300 TELOGIA CREEK 2009 1.0

1300 TELOGIA CREEK 2010 1.0

1303 QUINCY CREEK (POTABLE PORTION) 2005 3.0

1303 QUINCY CREEK (POTABLE PORTION) 2006 2.5

1454 FISH HATCHERY DRAIN 2007 1.3

1658 FISHHAWK CREEK 2005 2.0

1658 FISHHAWK CREEK 2006 1.6

1658 FISHHAWK CREEK 2007 3.4

1658 FISHHAWK CREEK 2008 1.7

1658 FISHHAWK CREEK 2009 1.6

1658 FISHHAWK CREEK 2010 4.4

1666 BULLFROG CREEK 1998 2.9

1666 BULLFROG CREEK 1999 1.8

1666 BULLFROG CREEK 2000 2.3

1666 BULLFROG CREEK 2001 3.8

1666 BULLFROG CREEK 2002 2.2

1666 BULLFROG CREEK 2003 1.3

1666 BULLFROG CREEK 2004 1.6

1666 BULLFROG CREEK 2005 2.0

1666 BULLFROG CREEK 2006 2.0

1666 BULLFROG CREEK 2007 1.8

1666 BULLFROG CREEK 2008 1.7

1666 BULLFROG CREEK 2009 1.8

1666 BULLFROG CREEK 2010 2.7

1686 UNNAMED CREEK 2006 4.3

1897 OAK CREEK 2005 1.5

1978 DEER PRAIRIE CREEK 1998 2.8

1978 DEER PRAIRIE CREEK 1999 2.2

1978 DEER PRAIRIE CREEK 2000 2.0

1978 DEER PRAIRIE CREEK 2001 1.7

1978 DEER PRAIRIE CREEK 2002 4.9

1978 DEER PRAIRIE CREEK 2003 1.7

1978 DEER PRAIRIE CREEK 2004 2.2
76

WBID Basin Year Geometric mean 

Chl-a (μg/L)

1978 DEER PRAIRIE CREEK 2005 1.3

1978 DEER PRAIRIE CREEK 2006 1.4

1978 DEER PRAIRIE CREEK 2007 2.4

1978 DEER PRAIRIE CREEK 2008 2.3

1978 DEER PRAIRIE CREEK 2010 1.2

2105 PIGEON CREEK 2008 1.4

2161 THOMAS CREEK 2001 1.0

2161 THOMAS CREEK 2008 1.5

2196 DEEP CREEK 2008 1.4

2211 MIDDLE PRONG ST MARYS RIVER 1996 1.3

2211 MIDDLE PRONG ST MARYS RIVER 1997 1.3

2211 MIDDLE PRONG ST MARYS RIVER 1998 1.0

2211 MIDDLE PRONG ST MARYS RIVER 1999 1.4

2211 MIDDLE PRONG ST MARYS RIVER 2000 1.3

2211 MIDDLE PRONG ST MARYS RIVER 2001 1.3

2211 MIDDLE PRONG ST MARYS RIVER 2002 1.3

2211 MIDDLE PRONG ST MARYS RIVER 2003 1.1

2211 MIDDLE PRONG ST MARYS RIVER 2004 1.2

2211 MIDDLE PRONG ST MARYS RIVER 2005 1.0

2211 MIDDLE PRONG ST MARYS RIVER 2006 1.6

2211 MIDDLE PRONG ST MARYS RIVER 2007 1.3

2211 MIDDLE PRONG ST MARYS RIVER 2008 1.0

2211 MIDDLE PRONG ST MARYS RIVER 2009 1.0

2264 CALKINS CREEK 2008 2.6

2407 GROG BRANCH 2007 1.1

2444 PETERS CREEK 1996 2.8

2444 PETERS CREEK 1997 3.1

2444 PETERS CREEK 1998 2.6

2444 PETERS CREEK 1999 2.7

2444 PETERS CREEK 2000 2.4

2444 PETERS CREEK 2001 3.2

2444 PETERS CREEK 2002 2.7

2444 PETERS CREEK 2003 2.3

2444 PETERS CREEK 2004 2.2

2444 PETERS CREEK 2005 1.5

2444 PETERS CREEK 2006 2.4

2444 PETERS CREEK 2007 1.4

2444 PETERS CREEK 2008 1.4
77

WBID Basin Year Geometric mean 

Chl-a (μg/L)

2444 PETERS CREEK 2009 1.5

2444 PETERS CREEK 2010 1.7

2444 PETERS CREEK 2011 2.3

2478 GREENS CREEK 2004 1.0

2478 GREENS CREEK 2007 1.3

2493 MOULTRIE CREEK 1996 1.2

2493 MOULTRIE CREEK 1997 0.8

2493 MOULTRIE CREEK 1998 0.7

2493 MOULTRIE CREEK 1999 1.5

2493 MOULTRIE CREEK 2000 2.2

2493 MOULTRIE CREEK 2001 1.4

2493 MOULTRIE CREEK 2002 1.1

2493 MOULTRIE CREEK 2003 1.0

2493 MOULTRIE CREEK 2004 1.1

2493 MOULTRIE CREEK 2005 1.4

2493 MOULTRIE CREEK 2006 1.3

2493 MOULTRIE CREEK 2007 1.3

2493 MOULTRIE CREEK 2008 1.1

2493 MOULTRIE CREEK 2009 1.0

2493 MOULTRIE CREEK 2010 1.2

2498 ATES CREEK 2005 1.0

2500 UNNAMED BRANCH 2002 1.0

2713 LITTLE ORANGE CREEK 1997 1.0

2713 LITTLE ORANGE CREEK 1998 1.0

2713 LITTLE ORANGE CREEK 2000 1.0

2713 LITTLE ORANGE CREEK 2005 1.1

2713 LITTLE ORANGE CREEK 2006 1.5

2905 JUNIPER CREEK 2005 1.2

2905 JUNIPER CREEK 2008 0.7

2905 JUNIPER CREEK 2009 0.7

2905 JUNIPER CREEK 2010 0.9

3035 TOOTOOSAHATCHEE CREEK 2005 1.0

3035 TOOTOOSAHATCHEE CREEK 2008 1.9

3042 JIM CREEK 2008 1.4

3086 CRABGRASS CREEK (WEST BRANCH) 2003 3.3

3086 CRABGRASS CREEK (WEST BRANCH) 2008 1.0

3164 FORT DRUM CREEK 2008 17.2

3324 ALAPAHA RIVER 2000 1.0
78

WBID Basin Year Geometric mean 

Chl-a (μg/L)

3324 ALAPAHA RIVER 2001 1.0

3324 ALAPAHA RIVER 2002 1.1

3324 ALAPAHA RIVER 2003 1.2

3324 ALAPAHA RIVER 2004 1.2

3324 ALAPAHA RIVER 2005 1.3

3324 ALAPAHA RIVER 2006 1.2

3324 ALAPAHA RIVER 2007 1.6

3324 ALAPAHA RIVER 2008 1.6

3324 ALAPAHA RIVER 2009 1.1

3324 ALAPAHA RIVER 2010 1.3

3351 ROCKY CREEK NEAR BENTON 2006 1.1

3351 ROCKY CREEK NEAR BENTON 2007 2.3

3351 ROCKY CREEK NEAR BENTON 2010 1.0

3388 DEEP CREEK 1998 1.6

3388 DEEP CREEK 2006 1.5

3448 ROBINSON CREEK 2006 1.4

3480 BETHEL CREEK 2006 1.0

3605 SANTA FE RIVER 2010 1.0

10C ESCAMBIA RIVER 2000 1.0

10C ESCAMBIA RIVER 2001 1.1

10C ESCAMBIA RIVER 2002 1.1

10C ESCAMBIA RIVER 2003 1.6

10C ESCAMBIA RIVER 2004 1.3

10C ESCAMBIA RIVER 2005 2.2

10C ESCAMBIA RIVER 2006 1.8

10C ESCAMBIA RIVER 2007 2.2

10C ESCAMBIA RIVER 2008 1.9

10C ESCAMBIA RIVER 2009 1.8

10C ESCAMBIA RIVER 2010 2.0

1329D WITHLACOOCHEE RIVER 2000 2.1

1329D WITHLACOOCHEE RIVER 2001 2.1

1329D WITHLACOOCHEE RIVER 2002 4.0

1329D WITHLACOOCHEE RIVER 2003 2.5

1329D WITHLACOOCHEE RIVER 2004 3.9

1329D WITHLACOOCHEE RIVER 2005 5.2

1329D WITHLACOOCHEE RIVER 2006 4.7

1329D WITHLACOOCHEE RIVER 2007 6.5

1329D WITHLACOOCHEE RIVER 2008 7.5
79

WBID Basin Year Geometric mean 

Chl-a (μg/L)

1329D WITHLACOOCHEE RIVER 2009 11.5

1329E WITHLACOOCHEE RIVER 2000 4.2

1329E WITHLACOOCHEE RIVER 2001 3.0

1329E WITHLACOOCHEE RIVER 2002 3.7

1329E WITHLACOOCHEE RIVER 2003 2.1

1329E WITHLACOOCHEE RIVER 2004 4.0

1329E WITHLACOOCHEE RIVER 2005 2.3

1329E WITHLACOOCHEE RIVER 2006 4.3

1329E WITHLACOOCHEE RIVER 2007 9.0

1329E WITHLACOOCHEE RIVER 2008 7.7

1329E WITHLACOOCHEE RIVER 2009 7.3

1351A OUTLET RIVER 2001 3.1

1351A OUTLET RIVER 2002 5.5

1351A OUTLET RIVER 2003 15.6

1351A OUTLET RIVER 2004 7.1

1443D HILLSBOROUGH RIVER 2005 1.2

1443D HILLSBOROUGH RIVER 2006 1.0

1443D HILLSBOROUGH RIVER 2007 1.4

1443D HILLSBOROUGH RIVER 2008 2.2

1443D HILLSBOROUGH RIVER 2009 1.2

1495A ITCHEPACKESASSA CREEK 2007 1.9

1495A ITCHEPACKESASSA CREEK 2008 9.8

160B SHOAL RIVER 2005 2.5

160B SHOAL RIVER 2006 5.0

160B SHOAL RIVER 2007 2.9

160B SHOAL RIVER 2009 1.6

1621B ALAFIA RIVER ABOVE FLINT HAWK 2000 1.0

1621B ALAFIA RIVER ABOVE FLINT HAWK 2001 1.2

1621B ALAFIA RIVER ABOVE FLINT HAWK 2002 1.2

1621B ALAFIA RIVER ABOVE FLINT HAWK 2003 1.2

1621B ALAFIA RIVER ABOVE FLINT HAWK 2004 1.0

1621B ALAFIA RIVER ABOVE FLINT HAWK 2005 2.6

1621B ALAFIA RIVER ABOVE FLINT HAWK 2006 2.1

1621B ALAFIA RIVER ABOVE FLINT HAWK 2007 2.0

1621B ALAFIA RIVER ABOVE FLINT HAWK 2008 1.7

1621B ALAFIA RIVER ABOVE FLINT HAWK 2009 3.2

1621B ALAFIA RIVER ABOVE FLINT HAWK 2010 3.5

1742B LITTLE MANATEE RIVER (NORTH 2005 1.8
80

WBID Basin Year Geometric mean 

Chl-a (μg/L)

FORK)

1742B LITTLE MANATEE RIVER (NORTH 

FORK)

2006 1.5

1742B LITTLE MANATEE RIVER (NORTH 

FORK)

2007 1.2

1742B LITTLE MANATEE RIVER (NORTH 

FORK)

2008 1.8

1742B LITTLE MANATEE RIVER (NORTH 

FORK)

2009 1.4

1807C MANATEE RIVER 2007 1.4

1869C MYAKKA RIVER (UPPER SEGMENT) 1999 2.4

1877A MYAKKA RIVER (UPPER SEGMENT) 1998 3.2

1877A MYAKKA RIVER (UPPER SEGMENT) 1999 1.6

1877A MYAKKA RIVER (UPPER SEGMENT) 2000 1.2

1877A MYAKKA RIVER (UPPER SEGMENT) 2001 1.0

1877A MYAKKA RIVER (UPPER SEGMENT) 2002 1.8

1877A MYAKKA RIVER (UPPER SEGMENT) 2003 1.3

1877A MYAKKA RIVER (UPPER SEGMENT) 2004 1.2

1877A MYAKKA RIVER (UPPER SEGMENT) 2005 1.4

1877A MYAKKA RIVER (UPPER SEGMENT) 2006 1.2

1877A MYAKKA RIVER (UPPER SEGMENT) 2007 1.4

1877A MYAKKA RIVER (UPPER SEGMENT) 2008 1.5

1877A MYAKKA RIVER (UPPER SEGMENT) 2010 1.8

18A EAST FORK 2005 5.0

18A EAST FORK 2006 5.0

18A EAST FORK 2007 3.0

18A EAST FORK 2009 1.1

2097K ST MARYS RIVER (NORTH PRONG) 1996 1.2

2097K ST MARYS RIVER (NORTH PRONG) 1997 1.9

2097K ST MARYS RIVER (NORTH PRONG) 1998 1.1

2097K ST MARYS RIVER (NORTH PRONG) 1999 3.2

2097K ST MARYS RIVER (NORTH PRONG) 2000 1.3

2097K ST MARYS RIVER (NORTH PRONG) 2001 1.1

2097K ST MARYS RIVER (NORTH PRONG) 2002 1.6

2097K ST MARYS RIVER (NORTH PRONG) 2003 1.0

2097K ST MARYS RIVER (NORTH PRONG) 2004 1.5

2097K ST MARYS RIVER (NORTH PRONG) 2005 1.0

2097K ST MARYS RIVER (NORTH PRONG) 2006 1.2

2097K ST MARYS RIVER (NORTH PRONG) 2007 1.2
81

WBID Basin Year Geometric mean 

Chl-a (μg/L)

2097K ST MARYS RIVER (NORTH PRONG) 2008 1.3

2097K ST MARYS RIVER (NORTH PRONG) 2009 1.0

2120B MILLS CREEK 2008 1.8

2415E BLACK CREEK (SOUTH FORK) 2005 1.0

24C BLACKWATER RIVER 2000 1.0

24C BLACKWATER RIVER 2001 1.1

24C BLACKWATER RIVER 2002 1.1

24C BLACKWATER RIVER 2003 1.0

24C BLACKWATER RIVER 2004 1.1

24C BLACKWATER RIVER 2005 1.1

24C BLACKWATER RIVER 2006 1.0

24C BLACKWATER RIVER 2007 1.1

24C BLACKWATER RIVER 2008 1.1

24C BLACKWATER RIVER 2009 1.1

24C BLACKWATER RIVER 2010 1.1

2551A LAKE TRIPLET DRAIN 2005 1.2

2929A BLACK WATER CREEK 1996 1.3

2929A BLACK WATER CREEK 1997 1.1

2929A BLACK WATER CREEK 1998 0.2

2929A BLACK WATER CREEK 1999 1.1

2929A BLACK WATER CREEK 2000 1.0

2929A BLACK WATER CREEK 2001 1.2

2929A BLACK WATER CREEK 2002 1.0

2929A BLACK WATER CREEK 2003 1.0

2929A BLACK WATER CREEK 2004 1.9

2929A BLACK WATER CREEK 2005 1.3

2929A BLACK WATER CREEK 2006 1.1

2929A BLACK WATER CREEK 2007 1.4

2929A BLACK WATER CREEK 2008 1.2

2929A BLACK WATER CREEK 2009 1.3

2929A BLACK WATER CREEK 2010 1.2

2929A BLACK WATER CREEK 2011 1.0

30B YELLOW RIVER 2003 1.0

3235E BEE BRANCH 2005 1.3

3235E BEE BRANCH 2008 2.8

3235G CYPRESS BRANCH 2005 3.2

3236A TELEGRAPH CREEK 1999 1.2

3236A TELEGRAPH CREEK 2000 3.3
82

WBID Basin Year Geometric mean 

Chl-a (μg/L)

3236A TELEGRAPH CREEK 2001 1.4

3236A TELEGRAPH CREEK 2002 1.4

3236A TELEGRAPH CREEK 2003 1.6

3236A TELEGRAPH CREEK 2004 1.9

3236A TELEGRAPH CREEK 2005 2.3

3236A TELEGRAPH CREEK 2006 2.0

3236A TELEGRAPH CREEK 2007 2.0

3236A TELEGRAPH CREEK 2008 3.0

3236A TELEGRAPH CREEK 2009 2.9

3236A TELEGRAPH CREEK 2010 1.8

3236A TELEGRAPH CREEK 2011 2.1

3310Z NUTALL RISE SPRING 2006 1.7

3310Z NUTALL RISE SPRING 2007 1.0

3506B NEW RIVER 2010 2.0

3506B NEW RIVER 2011 1.5

3573A STEINHATCHEE RIVER 2002 1.0

3573A STEINHATCHEE RIVER 2006 1.6

3573A STEINHATCHEE RIVER 2011 1.0

3605D SANTA FE RIVER 2001 1.6

375G APALACHICOLA RIVER 2001 1.2

375G APALACHICOLA RIVER 2005 3.7

375G APALACHICOLA RIVER 2007 1.4

793Z HORN SPRING 2006 1.6

793Z HORN SPRING 2007 1.0