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

REGIONAL MITIGATION PLAN
BACKGROUND INFORMATION
Mitigation Project: Myakka River State Park
Counties: Sarasota, Manatee
Project Number: SW51
Location: Sec. 19,26,28,29,30, T37S, R21E
IMPACT INFORMATION
(1) FM 1979251, SR 72 - Big Slough to DeSoto County Line ERP#: 43018471.000 COE #: 199802683
(2) FM 1980131, SR 72 - Deer Prairie to Big Slough ERP#: 44018399.000 COE #: 199802683
(3) FM 4138871, SR 72 – Myakka River to Big Slough ERP#: 43018399.001 COE #: 20057108 (IP-JP)
(4) FM 4227104, US 41 Flamingo Blvd. to Cranberry Rd. ERP#: ___________ COE #:
Drainage Basin: Myakka River Water Body(s):Big Slough, Deer Prairie Slough, Myakka River SWIM water
body? N
MITIGATION ENVIRONMENTAL INFORMATION
Mitigation Type: Enhancement
Mitigation Area: 1,274 acres
SWIM project? N Aquatic Plant Control project? N Exotic Plant Control Project? N Mitigation Bank? N
Drainage Basin(s): Myakka River
Water Body(s):Myakka River, Deer Prairie Slough
SWIM water body? N, but the Myakka River is an Outstanding Florida Water and Florida Wild & Scenic River
Project Description
A. Pre-Construction Site Conditions & Project Goal: Myakka River State Park & Myakka Prairie (“Park”,
37,000 acres, Figure A) is one of the largest state parks in Florida. The Park has a flat topography with a general
groundwater and surface water hydrology pattern that flows from north to south. There are two major constructed
features where historic flow regime was altered by fill embankment. These include the historic construction of a
9-mile long elevated east-west railroad tram during the early 1900’s within the northern portion of the Park, and
the elevated SR 72 segment crossing through the southern portion of the Park (Figures A & B). The tram was
constructed without use of culverts, blocking the natural southern sheet water flow hydrology pattern; resulting in
extended hydroperiods (depth & duration) within many wetlands to the north and reduced hydroperiods for
wetlands south of the tram (Figure B). The fill source for the railroad grade included ditches constructed along
each side of the tram. These ditches redirected and funneled contributing flow east and west along the tram to
North Deer Prairie Slough. The hydrologic conditions of many wetlands south of the tram have been further
altered by inter-connected ditches. The majority of the wetlands within the Park are ephemeral systems, so the
altered hydrology, vegetative zonation and restoration of appropriate hydrology and hydroperiods of these
wetlands has a direct correlation to the wildlife use, groundwater recharge, flood attenuation and water quality
improvements.
B. Brief description of conducted work & current habitat conditions: Evaluation by Park staff over many
years determined that surface and groundwater hydrology of impacted wetlands in the vicinity of the railroad tram
could be achieved by grading the fill material to match historic ground elevations, construction of wet crossings
at appropriate locations, and backfilling ditch segments (Figure B). The majority of these activities have been
completed and the flow regime successfully restored in the northern areas within the tram vicinity. The third SR
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