Introduction
The Paynes Prairie Preserve State Park is a 21,000 acre natural and historical landmark situated in Alachua County at the southern tip of Gainesville, Florida. Paynes Prairie is considered an Outstanding Florida Water and is a valuable resource that has been enjoyed by surrounding communities long before its inauguration as Florida’s first State Preserve in 1971.
Alachua Sink is a small lake located within Paynes Prairie, which receives flow from Sweetwater Branch and flows into a sinkhole with direct connection to the Floridan aquifer. Alachua Sink is currently listed as an impaired water body due to high nitrogen levels. A total maximum daily load (TMDL) has been developed for Alachua Sink, which will require reductions in total nitrogen loads from urban runoff, wastewater discharge and other sources. The proposed Sweetwater Branch/Paynes Prairie Sheetflow Restoration project provides a unique and innovative approach to achieving the regulatory water quality improvements, while providing additional environmental benefits. The project will also restore over 1,300 acres of impacted wetlands, provide protection of the Floridan aquifer, and offer outstanding wildlife habitat and opportunities for public recreation.
The project conceptual plan represents the culmination of focused efforts from a partnership of organizations including the Florida Department of Environmental Protection, St. Johns River Water Management District, City of Gainesville, Alachua County and the Florida Department of Transportation.
FIGURE 1: Approximate Boundary Map for the Paynes Prairie Preserve State Park Illustrating the Location of the City of Gainesville North of the Prairie and Sweetwater Branch Draining to Alachua Sink.
Background
The natural sheetflow of Sweetwater Branch onto the Prairie was disrupted by ranchers, in the 1930s, when they constructed a ditch to drain portions of the Prairie to expand grazing areas. The ditch diverts the Sweetwater Branch flow directly to Alachua Sink, and has resulted in the dehydration and alteration of over 1,300 acres of prairie wetlands. In addition, the direct connection of Sweetwater Branch to Alachua Sink provides a more direct conduit into the Floridan Aquifer. This channelization of Sweetwater Branch through the Prairie has prevented natural attenuation of the nutrients and has depreciated the water quality flowing into Alachua Sink.
Since most of the urban development in the Sweetwater Branch drainage area occurred long before modern stormwater management and other pollution control regulations, Sweetwater Branch, and in turn the Prairie have been heavily impacted by stormwater runoff. The Main Street Water Reclamation Facility also discharges treated effluent to Sweetwater Branch and is the main contributor of nutrients to the stream.
Conceptual Plan
The conceptual plan for re-establishing sheetflow of high quality water on Paynes Prairie includes upgrades to the Main Street Wastewater Reclamation Facility to optimize nitrogen and phosphorus removal. A 125-acre constructed enhancement wetland will polish the base flow from Sweetwater Branch before it is discharged to a mile long sheetflow distribution channel. Two miles of agricultural drainage canals will be filled so that wetland hydrology can be resorted.
FIGURE 2: Sweetwater Branch/Paynes Prairie Sheetflow Restoration Conceptual Plan
Water entering the Sheetflow Restoration Area must be of sufficient quality to allow the re-establishment of desirable, native wetland plant communities and wildlife habitat. This will require reductions in phosphorus in addition to Nitrogen. Project studies have establish the necessary quality levels to ensure that these criteria can be achieved through the proposed combination of Main Street Wastewater Reclamation Facility upgrades and the Sweetwater Branch Enhancement Wetland. These studies have also determined that additional assimilation of residual nutrients will naturally occur within the Sheetflow Restoration Area so that background nutrient levels similar to estimated pre-development concentrations will be achieved.
Project Benefits
The proposed project will restore Sweetwater Branch sheetflow to Paynes Prairie and at a minimum this project is expected to provide the following benefits:
- Restore (re-hydrate) over 1,300 acres of formerly-impacted wetlands in Paynes Prairie;
- Cost effectively attain regulatory water quality requirements for the City of Gainesville and the Florida Department of Transportation,
- Create about 125 acres of high-quality wetland wildlife habitat and a public use area for bird-watching and nature study within the Sweetwater Branch Wetland Park;
- Naturally assimilate nutrients, sediments and other pollutants in Sweetwater Branch in order to protect the PPPSP Sheetflow Restoration Area, Alachua Sink, and the Floridan Aquifer; and
- Restore part of the overall water balance to Paynes Prairie, which has been impacted by diversion of water from the Prairie at Prairie Creek.
Land Exchange
The City owns 30 acres of the 260-acre project site. 225 acres of the project site are located within the Paynes Prairie Preserve State Park. The St. Johns River Water Management District, Alachua County Forever and the City of Gainesville jointly purchased 276 acres of ranch lands located on the southern rim of Paynes Prairie, known as the Edwards tract. In August of 2009, the St. Johns River Water Management District and the City of Gainesville jointly donated 184 acres of the Edwards tract to the State of Florida in exchange for an easement over the project site. This 184-acre portion of the Edwards tract has been added to the Paynes Prairie Preserve State Park. The exchange was approved by the Florida State Lands Acquisition and Restoration Council in February of 2009. The remaining 92 acres of the Edwards tract will remain in Alachua County ownership, and will be managed by the Paynes Prairie Preserve State Park.
An additional 5 acres of the project site is owned by Alachua County. This property is adjacent to Williston Road and will be used to provide public access to the project site. The City of Gainesville and Alachua County are currently involved in negotiations to facilitate the exchange of the remaining parcel.
Implementation
The proposed Sweetwater Branch/Paynes Prairie Sheetflow Restoration Project will require several years and commitment from multiple organizations to implement. The estimated overall project cost is $23 million with an annual recurring operations and maintenance cost of about $1.3 million. The City of Gainesville has obtained a total of $1.5 million in funding assistance for land acquisition and professional design services. The City is continuing to pursue grant funding and cost sharing opportunities with project partners. The City’s goal is to obtain a total of 25% funding assistance.
Contacts
Stu Pearson, P.E.
Project Manager
Gainesville Public Works
pearsonsp@cityofgainesville.org
Alice Rankeillor, P.E.
Project Manager
GRU Strategic Planning
rankeilloai@gru.com