Saving Flatford Swamp
Abnormal tree die-off has occurred in Flatford Swamp and the upper reaches of the Myakka River watershed.
The cause of the tree die-off was excess water that entered the system due to land-use changes and structural alterations within the watershed. This excess water prevented the swamp from “drying out” part of the year, like it normally does.
The District purchased a majority of Flatford Swamp (2,357 acres) in 1991 under the Preservation 2000 program. The restoration of Flatford Swamp is the primary focus of the Myakka River Watershed Initiative.
Flatford Swamp is the heart of the upper Myakka River.
Five creeks and tributaries flow into this low basin, from which the Myakka River flows south to Charlotte Harbor.
Initial District studies back in the late 1990s concluded the tree die-off in Flatford Swamp was the result of excess water flows that entered the swamp from surrounding areas. The District’s Myakka River Watershed Intiative team set out to find a solution.
A key instrument used by the team to determine the amount of excess water in the swamp was the Upper Myakka River Water Budget Model. The water budget model allowed staff to compare existing hydrologic conditions to pre-, post- and potential future development scenarios over the same period of rainfall conditions. The information was used to identify how much excess water would need to be removed to help return the swamp to its historical hydroperiod.
Several alternatives to remove the excess water have been investigated. The most promising ways include:
- Transferring water from Flatford Swamp to the Floridan aquifer system through direct injection to benefit the Southern Water Use Caution Area
- Creating a recovery strategy for proposed Manatee River minimum flows and levels
- Using excess water from Flatford Swamp as an alternative source to groundwater for an industrial or other water user
Preliminary feasibility studies are proposed to investigate outstanding issues associated with use of the Flatford excess water. These studies — along with further natural systems evaluations, such as soils investigation — will begin under the Flatford Swamp Hydrologic Restoration Implementation project (H089).
Balancing the System
The Myakka River Watershed Initiative will evaluate water quality, natural systems and flood protection along the Myakka River.
The Myakka River watershed encompasses about 600 square miles and includes lands in Manatee, Sarasota and Charlotte counties, with small portions in Hardee and DeSoto counties. The river flows nearly 66 miles southwest from its headwaters, near Myakka Head in east-central Manatee County, until it discharges into Charlotte Harbor.
A River Runs Through It
The watershed possesses several unique and important natural and man-made surface water features such as Flatford Swamp, Tatum Sawgrass Marsh, and the Upper and Lower Myakka lakes. Through the Sarasota County segment, the Myakka River was designated an Outstanding Florida Water by the Florida Department of Environmental Protection, and it was named a Wild and Scenic River by the state of Florida in the late 1980s.
Though the river corridor is relatively unimpacted in many segments, alterations have been numerous, and significant in several locations, both within the river itself and the watershed. Cattle ranching and farming dominate the majority of the watershed, especially upstream of the Myakka River State Park. In addition, urbanization is growing throughout the watershed as farmland is converted into tracts for residential development.
Land alterations that were intended to manipulate flows and control flooding have also resulted in impacts with unintended consequences, such as damage to natural systems, increased flood stages and loss of floodplain storage. Because the watershed lies within the Southern Water Use Caution Area (SWUCA), water supply is also a major issue for the area.
Recognizing the importance of the Myakka River watershed, in February 2006 the Governing Board approved the Myakka River Watershed Initiative as a comprehensive watershed management study to assess these alterations and develop a strategy for mitigating water resource impacts within the watershed. The Myakka River Watershed Initiative will also evaluate the effects of land-use conversions and alterations to develop best management practices to restore natural systems, provide flood protection and address water quality and water supply issues.
The Myakka River Watershed Initiative’s goals are to:
- Define current conditions of the watershed with respect to the District’s four areas of responsibility (water supply, water quality, natural systems and flood protection)
- Evaluate the effects of historic and future land-use changes
- Develop and evaluate structural and nonstructural best management practices that will support:
- Alternative water supply development
- Water quality improvements
- Natural systems restoration (e.g., Flatford Swamp)
- Flood protection
There are four components to the Myakka River Watershed Initiative:
Digital Topographic Information
Determining the surface features and understanding the boundaries of each watershed is essential to developing the elements of the watershed management plan. This task involves reviewing the existing digital topographic maps and merging them together to create a computer model of the watershed’s surface for use in modeling later in the project.
Upper Myakka Water Budget
Although the project includes the entire Myakka River watershed, the District has given priority to developing a water budget for the upper Myakka and the Flatford Swamp areas. This includes assessing the surface water resources in the upper Myakka watershed by developing a computer model of the hydrologic cycle, evaluating the impacts to the land over time and developing restoration alternatives. The upper Myakka River watershed includes areas from the Sarasota gage, located at State Road 72, to headwaters upstream. Typically this work is conducted as part of the watershed management plan, but the task is scheduled earlier to address ongoing environmental concerns in the upper reaches.
The watershed evaluation determines each watershed’s storage capacity and water transportation features, including boundaries and the direction of water flow. This information is stored in the District’s geographic watershed information system database for access by users in the future.
At this step in the process, the Flatford Swamp area will be individually evaluated and accelerated on a parallel path with the remainder of the watershed.
Watershed Management Plan
Based on the information gathered from the watershed evaluation, a limited watershed management plan will be developed. The plan will provide a framework to determine the capacity of a watershed to provide adequate water for people and the environment, flood protection and good water quality. This information can be used to grade how well needs are being met within the watershed. Note that while floodplains will be evaluated, the formal mapping of floodplains for submittal to the Federal Emergency Management Agency is not included in the initiative.