Restoring Water Flows to Shark River Slough by Removing the Tamiami Trail Constraint

SFWMD Governing Board November 14, 2019

Robert Johnson National Park Service Surface Water Flow Pattern (1946) Historic Water Flow Patterns Matched the Landscape Features

Post Everglades Drainage District

Pre-C&SF Project Flow Modifications L‐30 40 L‐29 MB • Northeast Shark River Slough (L-31N to L-67 Ext.) –

L‐31N Historic flow path through Shark River Slough. Lower elevation region, dominated by submerged aquatic vegetation, and flooded year round.

• Western Shark River Slough (L-67 to 40 Mile Bend) – Higher elevated region, “floodplain” adjacent to Shark River Slough, dominated by emergent vegetation, and flooded seasonally.

• Eastern and Western Marl Prairies (pink areas) are the historic habitat for the Cape Sable Seaside Sparrow. Source: Parker et. al., 1955, Water Resources of Southeastern Florida, USGS, WSP 1255. 2 Water Flow Patterns into ENP were Altered by the C&SF Project

MWD WCA Levees ENP Experimental Incremental Completed Water Del. (1984) Field Testing (1963) (2015)

S‐12 Structures Opened

Uncontrolled Tidal Flows

3 Water Management Changes Impacted L-29 Levee (1960) Flows to Northeast SRS & Taylor Slough GSE 7.28 feet NGVD L-29 Levee Completion L-31N Canal Operations Post TS Dennis G‐596 L‐31N

Context Water Level (feet NGVD) Road Water Level Changes Gage G-596 (1949-2017)

Surface Water Flows Taylor Slough at Context Road (1967-1992) Monthly Flows (1,000 acre‐feet)

Sources: NPS and USGS. 4 Removing the Tamiami Trail Flow Constraint

Water Conservation Area 3B

Central Everglades L-29 Levee Removal and new L-67D Levee

Small Small Small G70 Bridge Bridges Bridges G69 S355A S355B S356 S333 Tamiami Trail S334 L‐29 1‐mile 2.3‐miles Bridges Bridge Western Central Eastern Tamiami Trail Next Steps Phase 2 • Three remaining roadway segments (green) will be reconstructed and raisedfrom 10.5 ft to 13.1 ft NGVD (6.5 miles). L‐31N 2013 MWD Bridge • Six small bridge spans (60-72 feet, see insert) would replace existing culverts, all other culverts replaced in-kind. 2019 Phase 1 Bridges Bridge Approaches • Gross Cost $100 Million, Design Tasks by the NPS July 2019-Feb. 2020. Construction Award Phase 2 Roadway by FDOT November 2020, construction complete by Nov. 2022. Reconstruction 5 Flow Distributions in Northeast Shark River Slough (2003-2019)

2019 Flow Increases Resulting from Bridging and L-29 Canal Stage Increases

2014‐2018

Pre‐2014

Pre–MWD No Bridges Post–MWD 1‐Mile Bridge Post–TTNS 3.3‐Miles Bridges Flow Section Discharges (cubic feet/second) (cubic Discharges Flow Section

Western Section Central Section Eastern Section 6 Pre-CERP Flows into Northeast Shark River Slough (2003-2019) TTNS 2.3‐Miles L‐29 Max. Bridging plus Raising the 8.5 feet NGVD L‐29 Canal Stage Constraint El Nino Hurricane Irma Coupled with Increased 2016 NESRS Inflows Lake Okeechobee Flows Deviation Constrained L‐29 Max. MWD 1‐Mile Bridge 8.5 feet and Partial Road Raising L‐29 Max. 7.5 feet NGVD Monthly Total Flows (1,000 (1,000 Total Flows Monthly acre-feet) Tamiami Trail Next Steps and the Central Everglades Project

• Goal: Sending more water south to reduce harmful discharges to the northern estuaries, and restore flows to the central/southern Everglades, requires increased outflow capacity from WCA-3A.

• Central Everglades Planning Project (CEPP) will redirect the majority of the new water eastward into Northeast Shark River Slough (the historic flow path).

• Requires reconstructing the eastern Tamiami Trail roadway, to accommodate the CEPP flows & design high water of 9.7 feet (NGVD) in the L-29 canal.

• The Tamiami Trail Next Steps phase 1 project constructed 2.3-miles of bridging in early 2019. These bridges are Remove L‐29 Levee aligned with the new CEPP flow path.

• The Tamiami Trail Next Steps phase 2 project will reconstruct/raise the remaining 6.5 miles of roadway, to protect the roadway from adverse high water impacts. 8 Tamiami Trail Next Steps Phase 2 Initial Typical Section

NEW ROADWAY FDOT NORTH WIDER SHOULDER SOUTH REPLACE SOD WITH PAVEMENT L-29 Canal FDEP/FDOT ENLARGE SWALES

CEPP DHW 9.7 feet NGVD

OLD ROADWAY Current DHW OLD ROADWAY 8.5L‐29 CANAL feet NGVD The new roadway would be raised from 10.5 to 13.1 to accommodate the CEPP design high water, and shifted southward by approximately 30 feet to accommodate the wider subbase and improved water quality treatment. Source: NPS, 2018 TT:NS VA Wksp. 9 Predicted Frequency of L-29 Canal Peak Stages

CERP 9.7 feet DHW (Tamiami Trail 13.1 feet)

Post ‐ MWD 8.5 feet DHW * Pre ‐ MWD (Tamiami Trail 10.5 feet) 7.5 feet DHW (Tamiami Trail ~ 9.7 feet) L-29 Canal Stage (feet NGVD) * Up to 90‐days/year

Source: NPS, 2010 TT:NS FEIS Return Period (Years) 10 11