The Everglades: Florida's River of Grass

The Everglades is a 6,105-square-kilometer subtropical wetland ecosystem in southern Florida, often called the "River of Grass" for the vast sawgrass marshes through which water flows in a slow, shallow sheet from Lake Okeechobee to Florida Bay. It is the largest subtropical wilderness in the United States and a UNESCO World Heritage Site.

Introduction

Unlike most wetlands, the Everglades is not a stagnant swamp but a dynamic, flowing system. Water moves southward at roughly 0.4 kilometers per day across a nearly imperceptible gradient, sustaining a mosaic of sawgrass prairies, hardwood hammocks, mangrove forests, and cypress swamps that together support extraordinary biodiversity.

Geographic Setting

• Location: Southern Florida, USA
• Area: 6,105 km²
• Type: Subtropical wetland
• Elevation Range: 0–2.4 m above sea level

The Everglades occupies the southern tip of the Florida peninsula, stretching approximately 160 kilometers from Lake Okeechobee to Florida Bay and the Gulf of Mexico. The entire system rests on a limestone bedrock platform that is nearly flat, with elevation changes measured in centimeters over kilometers. This gentle slope drives the sheet flow that defines the ecosystem.

The landscape is a patchwork of distinct habitats. Sawgrass marshes dominate the interior, while tree islands called hammocks rise slightly above the waterline and support tropical hardwoods. Along the coast, the largest contiguous mangrove forest in the Western Hemisphere lines the shores, transitioning to seagrass beds in Florida Bay.

Ecology & Wildlife

• Bird Species: Over 350
• Key Animals: American alligator, Florida panther, West Indian manatee
• Vegetation: Sawgrass, mangroves, cypress, periphyton

The Everglades supports over 350 bird species, including the roseate spoonbill, wood stork, snail kite, and great blue heron. It is the only place in the world where American alligators and American crocodiles coexist naturally. The endangered Florida panther, with fewer than 200 individuals remaining, depends on the upland areas adjacent to the wetlands.

Periphyton, a floating mat of algae, microbes, and calcium carbonate, forms the base of the Everglades food web. This seemingly unremarkable organism supports the entire ecosystem, from apple snails to wading birds. Invasive species, particularly the Burmese python, have severely disrupted native wildlife populations, reducing some mammal populations by over 90 percent.

Hydrology & Climate

• Water Source: Lake Okeechobee overflow and rainfall
• Flow Rate: Sheet flow at ~0.4 km/day
• Climate: Tropical, distinct wet and dry seasons
• Annual Rainfall: ~1,500 mm

The Everglades is driven by a seasonal cycle of flooding and drying. The wet season from May to November brings roughly 80 percent of annual rainfall, inundating the marshes and triggering breeding cycles for fish, amphibians, and wading birds. During the dry season, water concentrates in deeper sloughs and alligator holes, creating vital refugia for aquatic life.

Historically, Lake Okeechobee overflowed its southern rim during the wet season, feeding a sheet of water 80 kilometers wide and less than a meter deep across the Everglades. Twentieth-century engineering, including 2,500 kilometers of canals and levees, severed this connection and diverted over half the system's water for agriculture and urban development.

Conservation & Threats

• UNESCO Status: World Heritage Site since 1979
• Main Threats: Water diversion, pollution, invasive species, sea level rise
• Restoration: Comprehensive Everglades Restoration Plan (CERP)

The Comprehensive Everglades Restoration Plan, authorized in 2000 at an estimated cost of $10.5 billion, is the largest ecosystem restoration project in history. Its goal is to restore more natural water flow patterns while meeting the water needs of southern Florida's eight million residents. Progress has been slow but significant, with several major water storage and flow projects now operational.

Phosphorus runoff from sugar cane agriculture north of the Everglades has caused widespread eutrophication, replacing native periphyton with cattails and altering the food web. Rising sea levels threaten to push saltwater into freshwater areas, and Burmese pythons, descended from released or escaped pets, have become apex predators with no natural enemies in the system.

Key Facts

• The Everglades is the only place where American alligators and crocodiles coexist naturally.
• Water flows through the system at just 0.4 km per day across a nearly flat limestone platform.
• The Comprehensive Everglades Restoration Plan is the largest ecosystem restoration project ever undertaken.
• Over 350 bird species have been recorded in the Everglades.
• The ecosystem was designated a UNESCO World Heritage Site in 1979.

Fun Facts

• Alligator holes dug by American alligators serve as critical dry-season refuges for fish, turtles, and snails — making alligators ecosystem engineers.
• The Everglades is the only place on Earth where sawgrass marshes and mangrove forests exist side by side.
• Burmese pythons in the Everglades have reduced raccoon populations by 99 percent in some areas.

Final Thoughts

The Everglades is one of the planet's most irreplaceable ecosystems, a slow-moving river of grass that sustains extraordinary biodiversity on a razor-thin margin of water and elevation. Its restoration represents both a monumental engineering challenge and a test of whether modern society can coexist with the wild landscapes it depends upon.