The Tampa Bay Mitigation Bank:
A New Option for Wetland Mitigation in the Central Florida Region
The Federal Interagency Guidelines authorized wetland
mitigation banking legislatively (Federal Register 1995, Chapter 373).
The Tampa Bay Mitigation Bank (TBMB) is the first mitigation bank approved
in the Tampa Bay basin, and was developed in the headwaters of Cockroach
Bay, Manatee County, in response to the regionally expanding need for
freshwater and estuarine wetland mitigation. Recommendations established
for the restoration of Tampa Bay wetland habitats in Charting the Course
for Tampa Bay: The Comprehensive Conservation and Management Plan for
Tampa Bay (Tampa Bay National Estuary Program 1996) included the site
proposed by Tampa Bay Mitigation Bank. The TBMB consists of historically
agricultural, ruderal land in southern Hillsborough County on the Cockroach
Bay peninsula. Site development will be consistent with and expand on
the Cockroach Bay Habitat Restoration Project, a SWIM (Surface Water Improvement)
project undertaken by the Southwest Florida Water Management District
and the Hillsborough County Environmental Lands Acquisition and Protection
Program. The TBMB will produce 71.90 palustrine and 31.17 estuarine mitigation
credits by creating and/or restoring 81.26 acres of freshwater wetlands,
approximately 3.80 acres of freshwater ponds (a declining habitat required
for white ibis (Eudocimus albus) reproduction), 42.16 acres of tidal marsh/mangrove
wetlands, and 34.01 acres of upland and wetland hammock habitat. The TBMB
plan was developed in concert with other public efforts to improve the
ecological integrity of Cockroach Bay and is supported by the Cockroach
Bay Restoration Alliance, Hillsborough County, and the Tampa Bay National
Estuary Program. Scheduled for implementation in 2003, TBMB will restore
historical habitats and provide water quality benefits to Cockroach Bay
Aquatic Preserve and Tampa Bay.
Mitigation banking regulations in Florida were promulgated in 1994 (Rule
62-342, F.A.C. (1994)). Subsequently, 32 mitigation banks have been approved
throughout the state. TBMB is the first bank established in the Tampa
The approval process for a mitigation bank is complex,
and the proposal was reviewed extensively by state and federal regulatory
agencies since the bank was first proposed in 1997. Numerous resource
agencies also provided comments on the proposed plans. With the continued
urbanization of the Tampa Bay area, appropriate mitigation for critical
infrastructure projects within the watershed had been very difficult to
locate. The TBMB site will provide mitigation to offset projects permitted
within the watershed, and habitat restoration at TBMB will assist in meeting
goals established for bay habitats in Charting the Course for Tampa Bay,
the Comprehensive Conservation and Management Plan for Tampa Bay (Tampa
Bay National Estuary Program 1996), including estuarine and palustrine
wetlands and water quality enhancement to the Cockroach Bay Aquatic Preserve.
The proposed mitigation bank design was determined by characterizing existing
site conditions, including evaluations of habitat, hydrology, and sediments.
These analyses were used to identify proposed bank conditions based on
the potential to restore or create wetlands and upland habitat. Mitigation
bank credits were determined based on a comparison of habitat values between
the without bank condition and the proposed bank
condition following the approved credit assessment procedure promulgated
by the Mitigation Bank Review Team (Joint State/Federal Mitigation Bank
Review Team Process for Florida - Operational Draft 1998.). The difference
in pre- and post-restoration habitat value, or lift, was utilized
to establish the number of authorized mitigation credits for the bank.
The TBMB site consists of 161.2 acres surrounding the headwaters of Andrews
Creek, on the southeast portion of the peninsula between Little Cockroach
Bay and Cockroach Bay, east of the southern portion of the Southwest Florida
Water Management Districts (SWFWMD) Cockroach Bay Habitat Restoration
Project in southeastern Hillsborough County, Florida (Sections 22, 23,
Township 32S, Range 18E) (Figure 1).
Historic habitats on the site were a mosaic of hydric
hammock, swamp, pine flatwoods (both hydric and upland) and upland hammocks.
Approximately forty years ago, portions of the TBMB site were converted
to irrigated row crops and cattle grazing. Agricultural irrigation was
achieved by channelizing the headwaters of Andrews Creek, and ditches
were cut throughout the property to rapidly drain seasonally high water
and storm flows.
Presently, five plant communities occur on the site:
agricultural, herbaceous fallow field, shrubby old-field, disturbed upland
hammock, and disturbed palustrine emergent marsh. The eastern and northern
portions of the site remain in agricultural use, while the rest of the
site is ruderal and dominated by Brazilian pepper (Schinus terebinthifolius)
and similar undesirable herbaceous and shrub species. Drainage affecting
the hydrology of the site including 3.69 acres of palustrine wetlands
has encouraged the invasion of numerous Category 1 nuisance species (Florida
Exotic Pest Plant Council 2003). Palustrine emergent communities occur
marginally along Andrews Creek, the southwestern wetland, and two small
wetlands on the eastern portion of the property. The euryhaline estuarine
marsh community along the Andrews Creek channel receives freshwater inflow
that supports palustrine emergent vegetation including southern cattail
(Typha domingensis), interspersed with open mud flats. The southwestern
marsh is dominated by Brazilian pepper, in association with canna (Canna
flaccida), primrose willow (Ludwigia peruviana), cattail, and pennywort
(Hydrocotyle sp.). Wildlife utilization was determined to be extremely
limited due to the highly disturbed nature of the site and existing agricultural
use (Figure 2).
The channelization of Andrews Creek and ditching significantly altered
site hydrology. Additionally, a 35-foot concrete wall with a 5.8-foot
weir located near its center was installed c. 1950 across Andrews Creek
just east of the western boundary of the site to restrict tidal influence;
however, the weir no longer restricts discharges and tidal influx is minimally
inhibited by the structure. Hydrological information was obtained from
site topographical surveys, historic and recent aerial photographs, and
weekly sampling (5-1998 to 7-1999) at seven piezometers installed across
the site (Scarola Associates 1999). Typical seasonal high groundwater
(SHGW) elevations were established through site specific studies, and
rangefrom 0-0.33 m below the existing ground surface, declining closer
to the Andrews Creek channel (PSI 1998, Scarola Associates 1999). Due
to the alterations of the historic hydrologic regime and flow patterns
in the vicinity of the TBMB, wetlands restoration on site will require
stormwater runoff inflow from off-site basins to establish appropriate
wetland hydrology across the site (Scarola Associates 1999) (Figure 3).
Sediment samples were collected throughout the site based on topography
and soil mineralogy and analyzed for pesticides and heavy metals using
EPA Methods 6010 (heavy metals), 8081 (chlorinated pesticides), and 9060
(total organic carbon) to confirm that restoration of the site would not
affect endemic fauna. Sediment analysis showed that heavy metals and organo-chlorines
associated with sediments within the TBMB site were below probable effects
level and no effects to endemic fauna are expected following restoration(MacDonald
Restoration Plan Design
The restoration plan for the TBMB was designed based on using upstream
drainage for palustrine areas of the site, tidal inflow from Andrews Creek,
and elevational adjustment in all areas to establish appropriate hydroperiods
for wetlands communities (Figure 3). The plan was modeled after the Cockroach
Bay Habitat Restoration Project to the west and northwest of the bank
A mosaic of tidal and palustrine wetlands will be constructed
in conformance with the proposed restoration/creation plan, converting
approximately 81.26 acres of uplands to palustrine emergent wetlands,
varying by three hydroperiod and elevational regimes, and creating 3.80
acres of freshwater ponds for white ibis foraging habitat, which has been
declining regionally through hydrologic modification. Palustrine marsh
habitat will be vegetated by pickerel weed (Pontederia cordata), arrowhead
(Sagittaria lancifolia), maidencane (Panicum hemitomon), sawgrass (Cladium
jamiacense), and needle rush, (Juncus effusus) (Figure 4). Marsh areas
closer to Andrews Creek and tidal tributaries will be planted with euryhaline
An important element of the TBMB is the enhancement
of Andrews Creek and creation of tidal tributaries through elevational
adjustment allowing tidal inundation of excavated wetland basins through
Andrews Creek. Approximately 40.0 acres of low and high saltmarsh interspersed
with mangroves will be established through red mangrove (Rhizophora mangle)
planting and recruitment, and planting saltmarsh cordgrass (Spartina patens),
saltmeadow cordgrass (Spartina alterniflora), seashore paspalum (Paspalum
distichum), saltwort (Batis maritima), and glasswort (Salicornia virginica)
to accelerate saltmarsh establishment (Myers and Ewel 1994).
Approximately 2.21 acres of tidal creek mangroves will
be enhanced by opening the weir on the western property boundary and controlling
invasive plants (S. terebinthifolius, other spp.). Mangrove and estuarine
marsh habitat will be increased to 42.16 acres through wetlands enhancement
An upland buffer of live oak (Quercus virginiana), red
cedar (Juniperus virginiana), and cabbage palm (Sabal palmetto) will be
established on the property perimeter between the banks on-site
wetlands and off-site disturbed lands, and bordering selected interior
locations to separate wetland communities requiring different hydrologic
regimes, thus increasing landscape diversity (Figure 5).
Existing and proposed site conditions were assessed for all polygons in
accordance with the Joint State / Federal Mitigation Bank Review
Team Process for Florida (Joint State/Federal Mitigation Bank Review
Team Process for Florida Operational Draft 1998.) to establish
mitigation credits. For assessment areas containing freshwater, non-tidal
wetlands the Wetland Rapid Assessment Procedure (WRAP) was
used to establish credits (Miller and Gunsalus 1999). Mangrove or tidal
marsh wetlands polygons were assessed using the Estuarine Wetland
Rapid Assessment Procedure (EWRAP) (Joint State/Federal Mitigation
Bank Review Team Process for Florida Operational Draft 1998). These
two procedures are very similar, and the numeric results for individual
polygons are computed identically during calculation of WRAP/EWRAP variables.
The lift or delta between existing and proposed
conditions was determined and the delay in establishing a functionally
mature system was taken into consideration by application of a temporal
lag factor. The credit assessment was reviewed and modified by the federal
Mitigation Bank Review Team (MBRT), which included the U.S. Army Corps
of Engineers, U.S. Environmental Protection Agency, U.S. Fish and Wildlife
Service, and U. S. National Marine Fisheries Service.
Credits and Credit Release Schedule
Approximately 103 mitigation credits were established
for the TBMB through the MBRT process. Table 1 provides the number of
permit mitigation credits approved for each habitat type and the credit
release schedule for the bank.
TBMB credits will be released pursuant to the federally
approved credit release schedule, which differs from the schedule approved
by SWFWMD. State rules specify that freshwater credits may not be released
until success or compliance with all permit conditions has
been reached (Rule 62-342, F.A.C. 1994).
Long-term management will be provided in perpetuity
by the TBMB through establishment of a management trust fund. A public,
or approved private entity, may assume responsibility for management of
the bank upon determination of success with conveyance of the management
trust fund. Monitoring will be conducted quarterly for the first year
and annually for the subsequent two years to confirm establishment of
the targeted communities and adequate hydrology.
Mitigation Service Area
The banks approved Mitigation Service Area (MSA) includes the Tampa
Bay basin as depicted in the SWFWMDs ERP Manual (Figure 1). The
MSA for TBMB is consistent with SWFWMDs defined drainage basins
and the banks ability to offset environmental impacts in the region.
To utilize the bank, an applicant must ensure that the nature of proposed
impacts will be offset by participation in the bank and be within the
MSA, unless exempted by rule.
Tampa Bay Mitigation Bank, the first mitigation bank approved in the Tampa
Bay basin, will provide an approved regulatory option for mitigating estuarine
and palustrine wetland impacts within the watershed. Its proximity to
other sites chosen for restoration and preservation leverages the benefits
of the bank itself and other public efforts, and the location of the bank
was selected to enhance the restoration efforts already underway proximal
to the bank. The TBMB concept was determined to be appropriate for establishment
of a mitigation bank based on evaluation of the bank site location, the
mitigation plan, long-term operational sustainability, and the proposed
methods for determining lift between with and
without bank scenarios. Approximately 103 total credits were
established for the bank through the federal MBRT review process.
Birkitt Environmental Services, Inc., Caloosa Shell
Corporation, and Scarola Associates. 2002. Tampa Bay Mitigation Bank:
Final Mitigation Banking Instrument. Tampa, FL.
Federal Register. 1995. Federal Interagency Guidelines
for Mitigation Banking.
Florida Administrative Code. 1994. Rule 62.342, Mitigation
Florida Exotic Pest Plant Council. 2003 List of Invasive
Species. http://www.leppc.org/plantlist/03list.htm. Accessed 21 October
Lewis, R.L. and D. Robison. 1995. Setting Priorities
for Tampa Bay Habitat Protection and Restoration: Restoring the Balance.
Technical Publication #11-95 of the Tampa Bay National Estuary Program.
St. Petersburg, Florida.
MacDonald, D.D. 1994. Approach to the Assessment of
Sediment Quality in Florida Coastal Waters: Volume 1 Development
and Evaluation of Sediment Quality Assessment Guidelines. Florida Department
of Environmental Protection Office of Water Policy, Tallahassee, Florida.
Miller, R.E., and B.E. Gunsalus. 1997. Wetland Rapid
Assessment Procedure (WRAP) Technical Publication REG-001. South Florida
Water Management District, Natural Resource Management Division,West Palm
Myers, R.L. and J.J. Ewel, Editors, 1990. Ecosystems
of Florida. University Presses of Florida. 1990.
PSI. 1998. Results of the shallow subsurface investigation
seasonal high groundwater table determination, Tampa Bay Mitigation Bank,
L.L.C. Site, Ruskin, Florida.
Scarola Associates. 1999. Drainage Report for Tampa
Bay Mitigation Bank, Section 22 & 23, Township 32 S, Range 18E, Hillsborough
Tampa Bay National Estuary Program. 1996. Charting the
Course for Tampa Bay. Tampa Bay National Estuary Program in cooperation
with the U.S. Environmental Protection Agency, St. Petersburg, Florida.
U.S. Army, Corps of Engineers. 1998. Joint State/Federal
Mitigation Bank Review Team Process for Florida - Operational Draft. Jacksonville,
U.S. Department of Agriculture Soil Conservation Service
(NRCS), in cooperation with University of Florida Agricultural Experiment
Stations. 1989. Soil Survey of Hillsborough County, Florida.
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