Estuary and Coastal Waters

Numeric Nutrient Criteria

Workshop Introduction
Contacts and Other Information

Website: 

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

•Estuarine and Coastal Waters numeric nutrient plan

•Agendas

•Presentations

•Meeting Summaries

Contact Area Phone E-mail

Denise Miller Big Bend 850-245-8068 denise.miller@dep.state.fl.us

Nia Wellendorf Kings Bay/Crystal River 850-245-8190 nijole.wellendorf@dep.state.fl.us

Springs Coast

Ken Weaver 850-245-8414 kenneth.weaver@dep.state.fl.us
Introduction

 Meeting call to order

 Welcome and introductions

 Ground rules for meeting

 Scientific and technical discussion

 Expert input is primary purpose

 Public comment accepted after the technical discussion 

has concluded
Background

 EPA has made a formal determination that numeric 

nutrient criteria are “necessary” for estuarine and coastal 

waters

 Criteria will be proposed by EPA on January 14, 2011 and 

promulgated by October 15, 2011

 Unless the state submits and EPA approves numeric nutrient 

criteria prior to these dates

 EPA also proposed interim Estuary targets on January 14, 

2010, which could be promulgated on October 15, 2010.

 DEP is launching a collaborative effort to develop 

scientifically defensible and protective criteria values for 

marine waters

 Provide information to EPA

 Support potential state rule-making efforts
DEP Objectives

 Engage local organizations, stakeholders, and experts 

around the State to generate discussion and 

exploration of appropriate numeric nutrient criteria.

 Compile data and scientific support for recommended 

numeric nutrient criteria where such information is 

generated and available.

 Ensure that such information is accessible to both 

FDEP and EPA for consideration when moving forward 

with proposed numeric nutrient criteria.
Data Gathering Approach

 Regionalize waterbodies into relatively homogeneous 

units

 Describe physical/chemical factors, including causal 

parameters (nutrients) and supporting variables

(hydrodynamics, water residence time, transparency, 

salinity, DO, etc.)

 Describe biological response variables. The type, 

quality, community structure, and areal extent of 

valued ecological attributes will be documented, 

emphasizing those shown to respond to anthropogenic 

nutrient enrichment
Data Gathering Approach (cont.)

 Determine the sources and fates of nutrients, 

including assimilative capacity of the system

 Summarize scientific evidence quantifying the 

relationship between anthropogenic nutrient inputs 

and adverse effects on biological communities

 Identify existing regional nutrient loading models

 Other ideas?
Water Quality Standards

(see 40 CFR 131.3)

 Provisions of State/Tribal (or Federal) Law

 Designated Uses (Waterbody Goals)

 Criteria to protect those uses

 Antidegradation policy

 Water Quality Standards are to:

 Protect public health or welfare

 Enhance the quality of the water

 Serve the purposes of the Clean Water Act (provide a regulatory 

basis for source control and waterbody assessment)
Designated Uses

 CLASS I Potable Water Supplies

 CLASS II Shellfish Propagation or Harvesting

 CLASS III Recreation, Propagation and Maintenance 

of a Healthy, Well-Balanced Population of 

Fish and Wildlife
Water Quality Criteria

40 CFR 131.3

 A concentration, level or narrative statement

 Loading or concentration may be acceptable for 

nutrients

 Florida’s existing narrative: “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.”

 Represent a level of water quality that supports a 

particular use

 When criteria are met, water quality will protect the 

designated use
Water Quality Criteria

Requirements 

40 CFR 131.11

 States/Tribes Must adopt criteria that protect 

the designated use

 Based on a sound, scientific rationale

 Sufficient parameters to protect the

designated use

 Must support the most sensitive use

(for waters with multiple use designations)
Downstream Waters Protection

 40 CFR 131.10(b): In designating uses of a water body and the appropriate criteria for those uses, the State shall take into 

consideration the water quality standards of downstream waters 

and shall ensure that its water quality standards provide for the 

attainment and maintenance of the water quality standards of 

downstream waters.

 Critical importance when establishing numeric nutrient criteria

 EPA has proposed Downstream Protection Values (DPV) to be 

applied in upstream waters to be protect of downstream 

estuarine and coastal waters

 Protective TN loading targets were computed by reducing the 

current load by one half of the anthropogenic contribution.

 Loads were estimated using the UGSG SPARROW (Spatially 

Referenced Regression on Watershed Attributes ).

 EPA did not develop TN targets for: Caloosahatchee, St. Lucie, 

Biscayne Bay, Florida Bay, Ten Thousand Islands, and Rookery Bay. 
Downstream Protection Values

Example Downstream Protection Values

Our goal is to develop a sound scientific 

basis for protect nutrient levels in the 

estuary and potentially replace these 

numbers.
Numeric Nutrient Criteria

Considerations

 Protective of the most sensitive use; that is, prevent 

imbalances in natural populations of flora and fauna

 Nutrients exist naturally in the environment

 Nutrients are chemical elements and compounds found 

in the environment that plants and animals need to 

grow and survive

 Nutrients are not typically toxic

 Biological responses are highly site specific
Defining a Healthy, Well Balanced 

Aquatic Community as Basis For a 

Water Quality Standards Endpoint 

 Attributes of community structure and function must be 

considered

 Healthy, well balanced communities are not restricted to those 

described as “pristine” or “100% natural” 

 It is acceptable to have modest changes in biological community 

structure (compared to background) as long as :

 there are reproducing populations of sensitive taxa; 

 an overall balanced distribution of all expected major groups is 

maintained; and 

 ecosystem functions are largely intact due to redundant system 

attributes.
Dealing with Uncertainty/Variability

 All scientific measurements, and therefore, conclusions 

based on those measurements, contain a degree of 

uncertainty (known as statistical error).

 Lack of knowledge also introduces uncertainty.

 All biological systems, and often the associated water 

quality conditions, are naturally variable in space and time.

 Acknowledge uncertainty and variability when making 

decisions and provide a means for addressing them.
Conceptual Model for Relating Nutrient 

Enrichment to Designated Uses

Impacts

Human/Aquatic Life

Primary

Responses

Decreased Light

Availability

Extreme Chl-a 

Concentrations

Problematic 

Epiphytic Growth

Problematic 

Macroalgal Growth

Algal Dominance 

Changes

Diatoms to 

Flagellates

Benthic Dominance 

to Pelagic 

Dominance

Increased Organic 

Decompostition

Extreme Chl-a 

Concentrations

Problematic 

Macroalgal Growth

Secondary

Responses

Loss of SAV

SAV Spatial 

Coverage

SAV Spatial 

Coverage 

Trends 

Nitrogen and 

Phosphorus

External 

Nutrient Inputs

Mitigating

Factors

Color

Flushing

Residence time

Depth

Turbidity

Grazing

Harmful Algae

Nuisance 

Blooms

Toxic Blooms 

Low 

Dissolved

Oxygen

Anoxia 

Hypoxia 

Biological 

Stress 

Loss of Habitat

Commercial and 

Recreational Fishing

Aquaculture 

Tourism 

Nursery Areas 

Diversity 

Organism condition 

Ecosystem 

Function

Increase of Algal Toxins

Commercial and 

Recreational Fishing

Aquaculture 

Tourism 

Human Health 

Swimming 

Diversity 

Organism Condition 

Ecosystem Function

Fish Kills 

Commercial and 

Recreational Fishing 

Aquaculture 

Aesthetic Values 

Tourism

Diversity 

Organism condition 

Ecosystem Function 
Valued Biological Resources

 Type, quality, community structure, areal extent, etc. 

of biological communities, emphasizing those shown 

to respond to anthropogenic nutrient enrichment:

 Phytoplankton/ chlorophyll

 Zooplankton

 Submerged aquatic vegetation

 Benthic invertebrates

 Fish and other wildlife
Quantification of Adverse Effects of

Nutrients on Biological 

Communities

(Response Variables)

 Scientific evidence describing the relationship 

between anthropogenic nutrient inputs and adverse 

effects on biological communities

 Any variety of statistical treatment, such as correlation, 

regression, conditional probability analysis, 

deterministic model, etc.
Potential Nutrient Criteria for

Ecosystem Protection

(Causal Variables)

 Numeric targets needed for system protection or 

restoration

 Demonstrate the bases for these targets

 If nutrient target is achieved (assuming nutrients are 

the major source of stress), what level of response in 

the biology would be expected (complete or partial 

recovery)?
Objectives of Today’s Meeting

 Gather relevant data and information:

 Valued ecological attributes

 Response metrics

 Relevant stressors (nitrogen and phosphorus)

 Loading or concentration

 Technical approaches

 Ideally, come out with potential site-specific criteria

 Receive feedback on path forward

 Discuss potential numeric targets (loading or concentration) 

needed for protecting or restoring the system, including a 

demonstration of the scientific bases for the nutrient targets.

 Discuss connection of potential numeric targets to designated 

use protection (healthy, well balanced biology)

 Identify core individuals willing to assist DEP with the scientific 

exploration and documentation