2012 FDOT Mitigation Plan - Southwest Florida Water Management ...

After the salt marsh areas will have the B. pepper eradicated, spoil mounds removed, and partial filling of
mosquito ditches, where necessary, there will be supplemental planting of the same native herb species found in
the salt marsh. As with the designated mangrove enhancement, there will be additional salt marsh enhancement
than the 63 acres designated for mitigation credit (Figure E). However, the mitigation areas were delineated
within the locations that will receive the most ecological benefit from the construction-related restoration activities
associated with removing spoil and filling ditches. With the hydrologic improvements associated with the spoil &
ditch revisions, mangrove species will also naturally recruit and generate within portions of the salt-marsh habitat
restoration and enhancement.
Freshwater & Oval Oligohaline Ponds (3 acres) – Restoration within the oligohaline pond will focus on
opportunities to restore historic natural flow patterns and channel geomorphology, therefore a channel will be
opened up within the pond's western berm. This will allow for increased water flow within the upper reaches of the
creek system on the flood and ebb tides. Currently a majority of the ebb and flood tide enters the pond via the
north/south linear ditch into the southern opening of the pond, reducing the quantity of water available for flow
through the upper reaches of the creek. To further direct flow back through the natural system, the southern
opening of the pond will be closed through the construction of a shallow mangrove lined berm. The eastern and
western banks will be graded to create a littoral shelf and the exotic species and hard debris will be removed.
There will be a few additional littoral zones constructed in the northern freshwater ponds. All these littoral areas
will be planted with appropriate species. Depending on the salinity of each pond, these species could include
bulrush (Scirpus californicus), saw-grass (Cladium jamaicense), and cordgrass (Spartina patens, S. bakerii). To
enhance fisheries habitat, the hard debris excavated from the project area will be placed in the pond to create an
artificial reef.
Oligohaline Creek & Marsh Creation (6 acres) – There is an existing ditch parallel to the northeastern
boundary of the oval oligohaline pond. Bordered by a dominance of B. pepper, it was determined this location
and the two smaller borrow ponds southeast of the oligohaline pond would be a good location to construct a
meandering oligohaline creek and adjacent marsh habitat (Figure D & E). The cut material from constructing the
northern portion of the creek and marsh system will be used to fill and raise the grade of the two existing ponds
southeast of the oval oligohaline pond. Once constructed, the graded area will be planted with appropriate
species such as black needlerush, saw-grass, and cordgrass.
This habitat will provide additional water quality treatment and attenuation of water discharging from the
oligohaline pond before discharging into Mobbly Creek. Along with the littoral zone creation in the ponds, this
creek and marsh creation will provide the opportunity for fish migration between the pond and Mobbly Creek. In
turn, the increase in fish and aquatic species will attract other wildlife species that frequent the area such as
various wading birds and small mammals.
466