Developing an Integrated Assessment Model for

Old Tampa Bay:

Request for Input and Discussion from OTB Working

Group and Stakeholders OTB Kickoff MeetingDecember 1, 2011

Project Goal• Develop and

evaluate management actions in Old Tampa Bay to improve this segment’s ecological condition

2009 Pyrodinium bahamense bloom

Today’s Meeting Goal• Discussion between

Project Team and OTB Stakeholders on:– Priority Issues– Project Objectives– Management Actions– Expected Responses

to Management Actions

– Project Challenges

Old Tampa Bay Project TeamL. GarciaK. Kaufman

H. GreeningE. Sherwood

Old Tampa Bay Watershed• Open Bay Surface Area

(25%) vs. Watershed (75%)

• Urbanized Land Uses (65%) Dominate Watershed Area

• Total Freshwater Input- ~25% of Tampa Bay (2003-2007 Averages)

• TN Loads ~16% of

Tampa Bay (2003-2007 Averages)

Old Tampa Bay

Old Tampa Bay Hydrologic Alterations

• Alterations occurring as early as 1920s

• Watershed greatly urbanized

• Lake Tarpon / Brooker Creek watersheds now drain to Safety Harbor

• Causeways may be impeding bay circulation / flushing

1966-67Channel A

1969-70Channel G

1990-93Bayside Bridge

Primary Bay Management Driver• ~½ Bay’s Seagrass

Acreage Lost from 1950-1980

• Early 1990s – Tampa Bay Partners Adopt Baywide Seagrass Restoration Goal

• Seagrass recovery in OTB segment slower than the rest of the bay

Focus on OTB• Old Tampa Bay still shows signs

of poor recovery relative to other bay segments

• A number of focused studies in OTB point to additional management & research needs

• New challenges are being observed

Meeting Chl-a Thresholds?

2009 Pyrodinium bahamense bloom Safety Harbor Sediment Muck

Old Tampa Bay Key Assessments

Old Tampa Bay Priority Issues• Slower seagrass recovery in OTB segment

compared to the rest of the bay

• Periodic poor water quality (chlorophyll-a/ other light attenuation factors / D.O. in smaller embayments)

• Circulation and localized muck accumulation problems (fine-grained sediment transport issues within segment?)

• Pyrodinium blooms in 2008, 2009 and 2011

Input on Priority Issues• Consider spatial differences in wq

between N & S OTB

Old Tampa Bay Assessment:Preliminary Objectives (OTB Workgroup

2010)1. Determine the effectiveness of targeted nutrient reduction

initiatives (fertilizer ordinances, BMPs, coastal restoration)

2. Improve understanding of nutrient/hydrologic budget for OTB (particularly in ungaged drainages) to better pinpoint problem areas

3. Evaluate effects of remediating poor circulation in upper Old Tampa Bay through road modifications (Courtney Campbell Causeway / Bayside Bridge)

4. Evaluate effects of restoring freshwater flow regimes and habitats in coastal creeks and other restorable areas to better manage stormwater/nonpoint source inputs into the Old Tampa Bay system

5. Enhance monitoring capabilities to better understand the ecological conditions and responses in OTB

1. Evaluate effectiveness of nutrient reduction actions

• Tampa Bay Nitrogen Management Consortium Actions

• Regional Fertilizer Management Ordinances– Pinellas Co., City of Tampa

adopts TBEP Model Ordinance+– Hillsborough Co. educational

components

• Other BMPs Implemented by Partners

• Future reductions (WWTP to reuse, LID, etc.)

Willis 2011

2. Improve understanding of nutrient dynamics

• Groundwater input to OTB

• Tampa Bay Loading Model– 7 Source Categories– Non-point source loads

estimated from land use, soils, and rainfall in ungaged basins

• TMDL Development– Tampa Bay TMDL– FDEP/EPA have developed

additional nutrient loading targets in the watershed

3. Evaluate effects of remediating circulation

• Causeways and bridges

• Altering flow from Lake Tarpon, other channels

• Determine effects on water quality, sediment accumulation, seagrass growth and condition

1966-67Channel A

1969-70Channel G

1990-93Bayside Bridge

4. Evaluate effects of restoring flow

• Safety Harbor Sediment Assessment– Lake Tarpon Outfall Canal and surrounding urbanized stormwater

nutrient inputs promoting in-bay eutrophication

• Tidal Tributary Project– Reduce freshwater input “flashiness” from urbanizing watersheds– Restore more natural delivery of nutrients and flow to OTB

Protect Seagrass Resources

Tidal tributaries

Bay Proper

5. Enhance Monitoring Capabilities• Seagrass Response to Potential

Management Actions

• Pyrodinium bahamense Spring/Summer bloom formation– Opportunistic phytoplankton– Florida blooms occur in estuarine

locations with higher water retention times

– Estuarine sediments may influence its recurrence in OTB

• Ungaged/Urbanizing Basin Inputs

• Enhance Identification of Nutrient Sources / Sinks

2009 Pyrodinium bahamense bloom

FWCC-FWRI

Old Tampa Bay Assessment:Preliminary Objectives

1. Determine the effectiveness of targeted nutrient reduction initiatives (fertilizer ordinances, BMPs, coastal restoration) – • Perhaps lower priority due to lower fw and nutrient inputs into this bay

segment (residence times and circulation needs to be considered in this, as well as established TMDL)

• In-situ production vs. watershed inputs contribution to exceedences of regulatory thresholds

• Influence of sediment flux and other bay segment inputs on chl-a exceedences

• Changes to WWTP inputs to the system?-> effects on movement of discharge points?

2. Improve understanding of nutrient/hydrologic budget for OTB (particularly ungaged drainages) to better pinpoint problem areas• NE canal systems of OTB? -> Are these areas of significant nutrient

loading• Atmospheric deposition (major nutrient input to watershed and bay

surface)-

Input on Preliminary Objectives3. Evaluate effects of remediating poor circulation in upper Old Tampa Bay through

road modifications (Courtney Campbell Causeway / Bayside Bridge)

• Bridge abutment effects on sediment deposition within OTB

4. Evaluate effects of restoring freshwater flow regimes and habitats in coastal creeks and other restorable areas to better manage stormwater/nonpoint source inputs into the Old Tampa Bay system

• Influence of tidal trib inputs after salinity barrier projects are implemented

• Combination of scenarios needed to evaluate the system from multiple channelized inputs?

5. Enhance monitoring capabilities to better understand the ecological conditions and responses in OTB

BREAK??

Management ActionsAsking for:

• Input on Initial Management Actions Identified

• Potential New Actions

• Concerns with Identified or New Actions

Initial Management Actions for Evaluation

1. Redirecting/modifying significant freshwater discharges to/within OTB (Lake Tarpon Outfall, Roosevelt Basin, Alligator Creek, Channels A and G)• Effects on residence time/flushing in OTB? Hydrologic load vs.

nutrient load impacts? May have profound effects in localized areas within OTB.

• LT ASR /other FW supply timelines? Long-term planning for future demand?

• Unintended consequences—flood attenuation within watershed? Redirecting to where?

• Timing of delivery/magnitude of FW inputs– Are these inputs truly driving circulation within the bay segment?

• Consideration for large-scale climatic events [dry vs. wet years/pulsed flow events/prolonged climatic events (e.g. 3-4 years of drought/wet conditions)]

• Considering operation/discharge management of structures (top vs. bottom discharge)

2. Modifying operation of structures in Channels A and G to alter hydrologic inputs to Upper OTB

3. Adding culverts, bridge extensions to Courtney Campbell Causeway, Howard Franklin or Gandy Bridges

Initial Management Actions for Evaluation

4. Redirect existing WWTP direct discharge to reuse or other beneficial uses in the watershed• Consider feasibility (including costs /

permitting potential->but still reasonable / ROI->net environmental benefit) and unintended consequences of implementation

5. Implementing non-structural BMPs• Outreach activities within watershed

6. Implementing other BMPs (e.g., large regional stormwater treatment areas) in the OTB watershed

7. Removal of muck (dredging)• Dredging to improve circulation?

Locations1966-67Channel A

1969-70Channel G

1990-93Bayside Bridge

Assessment of Estuarine Response• Slower seagrass recovery in OTB segment compared

to the rest of the bay– Areal extent, species/bed composition (influence of attached

alga), deep-edge extent, growth rates/productivity– Ties into permitability of management action implementation– Tying seagrass habitat response to higher trophic level

response (e.g. fish population and assemblages) -- (monitoring a parameter vs. a response)

• Benthic algal contribution to ecosystem productivity

• Phytoplankton community composition and recent bloom dynamics trends/changes in species

• Consideration of benthic/zooplankton/fisheries community structure/populations– Ties into permatibility of management action implementation– Are these practical to simulate with a model?

Assessment of Estuarine Response• Periodic poor water quality (chlorophyll-a /

other light attenuation factors / D.O. in smaller embayments)– Nutrient speciation and delivery (form and delivery of

nutrient species to system)– Availability of new remote sensing products– Consideration of uncertainty of rate estimates that

drive water quality modeling

• Circulation and localized muck accumulation problems (fine-grained sediment transport issues within segment?)– Enhancing estimates of flow through bridge spans– Changes to the rate of muck accumulation in

response to management action implementation

• Consider spatial differences in wq between N & S OTB

• Aesthetics/Ecosystem Services? Human use benefits/components? Would help create public buy-in

Expected Estuarine Responses• Changes to the rate of muck accumulation in response to

management action implementation• Changes to residence time within OTB where Pyrodinium blooms

currently occur (cyst distributions)– Modeling water age within OTB (definition of residence time – an

important consideration)• Changes to salinity, D.O., chl-a (and other light attenuation

factors, e.g. CDOM, turbidity, etc.)• Changes to nutrient species concentrations within OTB• Dynamics/response of ephemeral seagrass beds (primarily

Halodule beds) (e.g. consideration of seed bank/plant fragment source influx, integrating rhizome monitoring)

• Linking model outputs to fisheries production will be difficult (but empirical approaches will be attempted to tie available habitat to fisheries production and composition)

Management Action Considerations

• Permitability• Costs

Model Considerations• Physical model/construct is paramount (resolution of

model will help determine whether model outputs are good/bad)– Deficiencies in SW-tidal exchange along bridge spans in OTB

• Use of available datasets to address key ecological responses

• Applicability of using existing/available model systems (EPA/TetraTech) as a starting point?– Future potential of model comparability

• Model Simulation constraints– Model vs. empirical approaches

• Feedback into model outputs (those parameters not possible to simulate)

• Uncertainty estimates of response