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Learn About Your Watershed

Alafia River Watershed

Image of The Alafia River originates from several creeks that converge into a centralized river system flowing to Tampa Bay.
The Alafia River originates from several creeks that converge into a centralized river system flowing to Tampa Bay. Neven Mrgan

Watershed Stats

Size of Basin: 410 square miles

Counties: Much of the eastern portion of Hillsborough County and a smaller area in the west-central part of Polk County

Major Towns: Portions of Lakeland, Plant City, Mulberry, and Brandon

Major Water Features: Alafia River; North and South Prongs; Lower Alafia River; Thirtymile Creek; Poley Creek; English Creek; Horton Creek; Hamilton Creek; Howell Creek; Sloman Branch; Bird Branch; Spring Brook; Lake Drain; Mizelle Creek; Harrah Creek; North, West, Chito, Owens, Halls, McMullen, Pollard, Boggy, Gully, Lake, McDonald, McCollough, and Pellham Branches; Turkey, Fishhawk, Little Fishhawk, Bell, Boggy, Buckhorn, Rice, and Breezey Creeks; Edward Medard Reservoir (Pleasant Grove Reservoir); Lakes Grady, Scott, and Wimauma; and Lithia and Buckhorn Springs

Overview

Image of The South Prong of the Alafia at Alderman Ford.
The South Prong of the Alafia at Alderman Ford. Gitta Schmitt

The Alafia River originates from several creeks that converge into a centralized river system flowing westward from Polk County through Hillsborough County. It flows 24 miles westerly into lower Hillsborough Bay, the northeastern segment of Tampa Bay. The North Prong, which is about 10 miles long, originates in Polk County to the west of Plant City and south of Lakeland. The South Prong, which is about 25 miles long, originates at Hookers Prairie in southeast Polk County.

The Lower Alafia River lies downstream of the confluence of the North and South Prongs, flowing westerly in a well-defined channel to the Gulf of Mexico at Hillsborough Bay near Gibsonton. Approximately five miles upstream from the river's mouth, the channel widens and becomes tidally influenced.

The watershed contains at least 17 lakes and one reservoir. The Edward Medard Reservoir (a reclaimed phosphate pit, also known as Pleasant Grove Reservoir) is the largest waterbody at 770 acres. Two major springs, Lithia Springs and Buckhorn Springs, are also found on the Alafia River.

Generally, urban, industrial, and commercial activities characterize the northern and western portions of the watershed, while agriculture dominates the southern portion, and mining dominates the eastern portion. The predominant land use in the watershed is mining-principally for phosphate-which consumes 28 percent of the total area.

Image of Main spring at Lithia Springs, which flows into the Alafia River.
Main spring at Lithia Springs, which flows into the Alafia River. Christine Karl Phares

Agriculture comprises about 27 percent of the watershed's total area. Although this activity occurs throughout the watershed, it predominates on the north side of the North Prong and some areas in the central portion. Agriculture in Hillsborough and Polk Counties includes citrus, poultry, dairy, strawberries, and other row crops. Approximately 17 percent of the watershed is urban. Urban activities dominate the western half of the watershed and areas in and near Lakeland, Plant City, Mulberry, Brandon, Riverview, and Gibsonton.

Historically, the Alafia River watershed comprised a wide variety of upland, wetland, and coastal habitats. Some large tracts containing intertidal marsh, mangrove forests, freshwater wetlands, swamps, and forested uplands remain undeveloped. The adjacent floodplains along the middle and upper (North and South Prongs) reaches of the Alafia River contain the most extensive areas of remaining natural lands.

While some of these undisturbed lands are privately owned, other large tracts in public ownership protect several miles of the river, its associated floodplain swamps, and the headwaters. These include lands co-owned by the SWFWMD and the Hillsborough County Environmental Lands Acquisition and Protection Program (ELAPP), which were acquired to protect water resources, wildlife habitats, and natural systems. They contain extensive areas of natural floodplain forests and swamps. Natural uplands border the river floodplain, forming a diverse landscape of wetland and upland habitats. Wildlife populations include listed species considered significant and regionally important.

Human Impacts

By the early 1990s, human activities-principally mining and urban, suburban, commercial, industrial, and agricultural uses-had altered over 91 percent of the watershed. In particular, large-scale phosphate mining has resulted in significant ecological impacts. Historically, thousands of acres of uplands and wetlands were removed or altered through the extraction of underground phosphate ore. Altered surface water and ground water hydrology from phosphate pit excavation also dewatered and in some cases degraded adjacent freshwater wetlands. Most impacts have occurred in the eastern watershed between the north and south prongs of the Alafia River. Urbanization has been and continues to be a major agent of change.

Image of By the early 1990s, human activities-principally mining and urban, suburban, commercial, industrial, and agricultural uses-had altered over 91 percent of the watershed. In particular, large-scale phosphate mining has resulted in significant ecological impacts.
By the early 1990s, human activities-principally mining and urban, suburban, commercial, industrial, and agricultural uses-had altered over 91 percent of the watershed. In particular, large-scale phosphate mining has resulted in significant ecological impacts. FDEP

Land clearing that began in the 1920s and 1930s for agricultural and mining , as well as dredge and fill activities, has resulted in a patchwork landscape of disturbed and native habitats, accompanied by significant invasions of exotic plant species in many privately owned areas and nearly all publicly owned and protected lands.

Continued nonpoint source pollution is of particular concern because of the cumulative impacts to remaining natural habitats from water quality degradation. The problem is especially acute in Hillsborough County, in part because of the close intermingling of surface water and ground water, which creates the potential for ground water contamination. In addition, the contaminants that flow to surface waters in the Alafia watershed eventually reach Hillsborough Bay.

Both Turkey Creek and Lithia Springs contribute degraded water to the Alafia River. Lithia Springs has periodically been closed due to elevated bacteria levels. The Medard Reservoir has a number of water quality problems, including elevated levels of fecal andl coliform bacteria. The reservoir's swimming area has been closed numerous times due to elevated bacteria levels. Lakes Hickory Hammock, Carlton, and Grady have high biochemical oxygen demand (BOD).

In recognition of these impacts, DEP, SWFWMD, and local governmental, scientific, educational, and citizen organizations are working to develop strategies for protecting and restoring water quality in the Alafia River watershed.

Interesting Facts:

  • In 1997, a breach in a containment wall at the Mulberry Phosphates facility released 50 million gallons of phosphoric acid wastewater in the headwaters of the North Prong Alafia River. The spill caused a fish kill and affected water quality in Skinned Sapling Creek and the Alafia River in Polk and Hillsborough Counties.
  • Lake Wimauma generally has the best water quality of all the lakes in the Alafia River watershed.
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