Estuary Numeric Nutrient Criteria Public 

Meeting for Portions of the Florida Coast 

from Pinellas County to Lee County, 

Meeting Notes 

Thursday, February 4. St. Petersburg, Florida. 78 attendees.

Charles Kovach and Russ Frydenborg, Florida Department of Environmental Protection (DEP), opened up 

the meeting by welcoming everyone and thanking them for their participation. 

Presentation: Estuary and Coastal Waters Numeric Nutrient Criteria Workshop Introduction, by Russ 

Frydenborg, DEP

Russ then answered a few clarifying questions about the criteria development process, and the role of 

the U.S. Environmental Protection Agency (EPA) and DEP. An audience member asked if EPA are 

committed to using the regional information that DEP is collecting, and Russ explained that DEP and EPA 

are working collaboratively and that EPA has said that they will consider all information provided to 

them.

Presentation: A nitrogen management strategy based on the quantitative relationships between 

nitrogen loading, algal biomass, and seagrasses in Tampa Bay, Florida, by Dr. Tony Janicki, Janicki 

Environmental, Inc. 

Tony explained the existing Total Nitrogen (TN) TMDL that sets TN loads and chlorophyll a concentration 

targets for Tampa Bay, by bay segment. The proposal is to assess chlorophyll a values annually, and 

then assess nutrient loads if the chlorophyll a targets are exceeded two years in a row. Ed Sherwood of 

the Tampa Bay National Estuary Program (NEP) noted that a very extensive support document had been 

prepared to support this TMDL, which would translate into protective criteria for the Bay. The 

reasonable assurance document can be found at 

http://www.tbeptech.org/attachments/050_FINAL_NMC_APPROVED_2009_RA_Addendum_Package_0

9112009.pdf

Presentation: Estero Bay Nutrient levels and loads, by Keith Kibby of Lee County

Estero Bay is part of the Charlotte Harbor NEP, and was included in some water quality and seagrass 

targets set by the NEP by Catherine Corbett et al. in the 2000’s. However, it is not part of the current 

work by Tony Janicki to further define water quality targets for the NEP. Estero Bay seagrasses are at 

their highest coverage on record. It is a shallow estuary and can become very turbid. Turbidity has 

increased in the Imperial River part of the Bay and seagrasses have declined in that section. 
Presentation: Setting Numeric Nutrient Criteria for the Charlotte Harbor NEP, by Tony Janicki, Janicki 

Environmental, Inc.

Water quality target refinement ongoing for protection of 1950’s seagrass coverage, and report will 

soon be available on the Charlotte Harbor NEP website. His goal is to complete the work in time for

submission to EPA in June. It would be good to keep open the option of combining the nutrient criteria 

proposal with color and turbidity criteria proposals because those are big factors in light attenuation in 

Charlotte Harbor. A participant in the audience suggested that because Lemon Bay and Dona and 

Roberts Bay are very hydrologically altered, restoring historical seagrass coverage may not be a 

reasonable goal.

Presentation: Sarasota Bay – implications for EPA’s proposed numeric nutrient criteria, by Dr. Dave 

Tomasko, PBS&J Consulting Firm

Sarasota Bay has been a National Estuary Program (NEP) for >20 years, and a lot of effort and money has 

been spent to reduce nutrient loads and improve the water quality of the Bay and the coverage of 

seagrasses. Huge gains have been made and measured, especially due to decreased load from the 

Wastewater Treatment Plants. Although TN loads have been reduced significantly (60-80%) and 

seagrass acreage has increased to coverage that is greater than in the 1950s, there have not been 

commensurate reductions in the chlorophyll a concentrations. However, epiphyte loads on seagrasses 

have been reduced, which has increased light available to seagrasses despite smaller chlorophyll a

reductions. Dr. Tomasko advocated a hold-the-line approach for TN. There was a short discussion 

about the SPARROW model after Dr. Tomasko’s presentation because he showed that the downstream 

protection value (DPV) for Sarasota Bay tributaries (0.54 mg/L TN) was approximately half of the TN 

contributed by completely natural land uses in that region. A participant in the audience said that he 

thought that EPA misapplied the SPARROW model for use in Florida estuaries. Several participants said 

that SPARROW was not a bad model, but that the output was not right at all. 

Question: Should the criteria be a concentration or load?

Answer: If there is more rain, the loads are higher even though concentrations are lower, so the criteria 

should not only be load. A combination of load and concentration might be appropriate. There is also a 

strong relationship between salinity and TN, so salinity could be used in the criteria construction, to 

account for differences based on freshwater content.

Question: Do we need to address phosphorus in Sarasota Bay?

Answer: A hold the line approach might be appropriate for TP. Research has shown that additional TP 

does not cause an increase in chlorophyll a in Tampa Bay, Sarasota Bay, or Charlotte Harbor.

Presentation: Exploring Clearwater Harbor and St. Joseph Sound, by Kelli Hammer Levy of Pinellas 

County

St. Joseph Sound has very diverse community of macroalgae and shellfish, as well as seagrasses, and 

chlorophyll a concentrations range from 2-4 μg/L. All freshwater systems are gaged, and loading 

estimates are currently underway. Tony Janicki is currently working on connecting water quality to 
aquatic life use support. Kelli said that St. Joseph Sound is probably limited by phosphorus as well as 

nitrogen, due to a lot of karst area in the watershed. She noted that Pinellas County should not be 

considered part of the Bone Valley, as in the EPA freshwater nutrient criteria proposal. 

Break for Lunch

Presentation: Nearshore Coastal Modeling, by Dr. R.H. (Bob) Weisburg of the University of South Florida 

(USF)

Dr. Weisburg talked about the importance of flushing of the bays by the ocean, and the prominent role 

that nutrients from deep offshore sources can play in estuary nutrient dynamics. He talked about red 

tide blooms that originated offshore and traveled in deep waters to shore. He discussed the 1998 

upwelling of nutrient-rich water from off the Big Bend coast that contributed to higher nutrient 

concentrations in marine waters in 1998. He demonstrated his flushing models, available at 

http://ocgweb.marine.usf.edu

Presentation: Remote Sensing Tools to Estimate Chlorophyll a, by Dr. Chuanmin Hu of USF

Dr. Hu discussed the use of satellite imagery to estimate chlorophyll a concentrations offshore. Cruise 

water sample data are used to determine the accuracy of the estimates, and in general, both sets of 

data show the same trends, although the satellite estimates are only accurate within an order of 

magnitude. 

After all of the presentations, there was a general question/answer and discussion session, during which 

the following information was agreed upon by all present, to guide DEP’s efforts. 

Estuary System Most Sensitive Organisms Causative Agent Loading Models?

Tampa Bay SAV TN (limit), TP (hold line) Done

Sarasota Bay SAV TN (limit), TP (hold line) Done

Charlotte Harbor SAV, maybe Macroalgae, 

PLRG for Hypoxia

TN (limit), TP (hold line) In progress for northern 

portions, some work for 

southern, targets for 

oysters and juvenile fish

Clearwater/St Joseph 

Sound

SAV, Macroalgae, Sponges TN (limit), TP (possibly 

limit)

In progress

Additional considerations:

• If chlorophyll is too low, fishery could be harmed.

• Could use load or concentration for the criteria, can get one from the other.

• NEPs go through extensive peer review in their management plan process, even if not published 

in peer-reviewed journals. 

• DEP will prepare a draft outline of Nutrient Criteria proposal summaries for each estuary, and 

send assignments to folks willing to help write them.