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Florida has three kinds of rivers: alluvial, blackwater and spring-fed.
Alluvial river — A type of river with a large, well-defined drainage basin that carries a high sediment load and has a large forested floodplain. The Apalachicola, Choctawhatchee, Escambia and Ochlockonee rivers are examples.
Blackwater river — A type of river that drains pine flatwoods and cypress swamps and has dark, stained waters from decomposing plant material. The Withlacoochee, Hillsborough and Peace rivers are examples.
Spring-fed river — A type of river with cool, clear water issuing from springs. Examples include the Weeki Wachee, Rainbow and Crystal rivers.
Alluvial rivers are found in the Panhandle. Fed by summer storms, they overflow their banks each year, spreading nutrient-rich sediments over broad, fertile floodplains.
Spring-fed rivers are characteristic of north-central Florida, where cool, clear waters stream from permeable layers of limestone just beneath the surface of the ground.
Although it’s nourished by springs, the Peace is primarily a blackwater river. Its waters are a dark brew of leaf detritus, organic acids and tannin, distilled from the peaty soils of the wetlands and forests through which it flows.
Strictly speaking, the Peace gets its fresh water from rainfall, as do all of Florida’s rivers, lakes, springs and aquifers located south of the “hydrologic divide,” a line bisecting the peninsula from Cedar Key on the west coast to New Smyrna Beach on the Atlantic. Although fresh water enters northern Florida from Georgia and Alabama, none of it flows south of the hydrologic divide.
From its headwaters in Polk County, the Peace River meanders through swamps, pine flatwoods, hardwood hammocks and marshes before it fans out into the Charlotte Harbor estuary.
Its watershed encompasses over 2,300 square miles. Locals call it the Peace River Valley. It’s bordered on the west by western Polk, Manatee and Sarasota counties, and on the northeast by the Lake Wales Ridge, the oldest and highest geological formation on the Florida peninsula.
The watershed is low and flat, peppered with shallow lakes and wetlands, and partially flooded by summer rains. It includes nine subbasins:
- Peace River above Bartow
- Peace River above Zolfo Springs
- Peace River above Arcadia
- Lower Peace River
- Paynes Creek
- Charlie Creek
- Horse Creek
- Joshua Creek
- Shell Creek
The climate is humid and subtropical throughout. The temperature averages about 73 degrees. Annual rainfall averages between 50 and 56 inches, with more than half occurring between June and September. Most of the rainwater reenters the atmosphere through evaporation and plant transpiration. The rest recharges the aquifer or seeps into the Peace River and its tributary streams. Responding to the dynamic rainy season, the river peaks in late summer and early fall (unlike the rivers of north Florida, which achieve their peak flows in late winter and early spring).
For much of its length, broad, sandy deltas alternate with tree-lined bluffs, a topography geologists refer to as “flashy” because it’s prone to flash flooding. During the rainy season, rising waters erode the bluffs, undercutting the trees. Those that topple in become snags for waterborne debris — and unwary boaters.
The riverbed consists of layers of sand, clay and limestone particles. The layers were formed from the fossil remains and waste products of ancient marine organisms deposited on the floor of the ocean during the Miocene Epoch, between 5 million and 26.5 million years ago. The fossil layers contain phosphate, which leaches into the river in the form of phosphorus, an essential component of fertilizer.
When the river reaches Charlotte Harbor, the phosphorus interacts with mangrove detritus and other nutrients, helping to fuel the richest, most productive estuary system in Florida.
Next section: Ecological diversity