Alafia River

The Alafia River is a river in Hillsborough County, Florida. It flows into Tampa Bay and drains a watershed of 335 square miles. The river begins in Lithia, where the North Prong (23.9 miles long) meets the South Prong (28.7 miles long). From there the combined river runs about 24.7 miles west to Hillsborough Bay at Gibsonton, passing Riverview on the way. The Southwest Florida Water Management District calls it a major tributary of Tampa Bay. The District and Hillsborough County bought land along the river together as the Alafia River Corridor, which the county manages. The river floods at moderate to high levels about twice a year.

Hillsborough County runs the public ramps on the tidal lower river. Each charges $5 to launch a boat. Williams Park Boat Ramp is a four-lane ramp next to the U.S. 41 bridge and connects to the river and Tampa Bay. The Riverview Civic Center on Park Drive has a one-lane ramp, a dock and a canoe and kayak launch. The Alafia River Boat Ramp, also called the Brandon Boat Ramp, is a single lane off Alafia Boulevard. The county requires boaters to follow posted idle and slow-speed zones, and swimming is prohibited at these ramps. State manatee protection zones are mapped on the lower river. In 2023 the county marked a navigation channel 650 feet long and 150 feet wide near Williams Park to keep anchored boats out of the main waterway. Upstream, a 10-mile state-designated paddling trail runs from Alderman's Ford Park to Lithia Springs Park, with occasional shoals and easy rapids. Paddlers may not enter the spring area at Lithia Springs.

In 1997 a gypsum-stack dam at a Mulberry Phosphates plant failed and spilled 56 million gallons of acidic wastewater into the North Prong. The spill killed nearly everything in the 42 miles of river between Mulberry and Hillsborough Bay.