A river like no other
The Florida Everglades is often called the "River of Grass," a name popularized by writer Marjory Stoneman Douglas in 1947. This is not a metaphor. It describes a unique hydrological phenomenon called sheet flow. Unlike a typical river confined to a channel, the Everglades is a vast, slow-moving sheet of water that historically flowed over 100 miles from Lake Okeechobee south to Florida Bay. This river is exceptionally wide, reaching up to 60 miles across, yet it is incredibly shallow, with water depths often measuring in inches.
The movement of this water is almost imperceptible, advancing at an average rate of about 34 meters per day. This creeping pace is due to the landscape's extremely gentle slope, which drops only about two inches per mile. The porous limestone bedrock and the dense resistance of emergent vegetation, primarily sawgrass (Cladium jamaicense), further regulate the water's speed. This process is so slow that water leaving Lake Okeechobee might take months or even years to complete its flow to the sea. This gradual flow has shaped every aspect of the South Florida ecosystem for the past 5,000 years.
At the base of this aquatic system is periphyton, a complex community of algae, cyanobacteria, microbes, and detritus. This floating mat covers huge areas of the marsh, oxygenates the water through photosynthesis, and is the primary food source for snails, invertebrates, and small fish, which in turn feed larger animals like alligators and wading birds.
A system broken and being repaired
In the 20th century, a massive network of canals, levees, and water control structures was built to support agriculture and urban development. This engineering effort drained and compartmentalized the ecosystem, reducing the Everglades to about half of its original size. The sheet flow was severed. Instead of flowing south to nourish the marshes and Florida Bay, vast quantities of fresh water were diverted and discharged into the Atlantic Ocean and the Gulf of Mexico.
The consequences were severe. The disruption of the slow, steady supply of fresh water led to periods of hypersalinity in Florida Bay. This change contributed to widespread seagrass die-offs and damaging algal blooms, impacting the entire marine food web. The number of nesting wading birds in the Everglades plummeted by an estimated 90% as their food sources and habitats disappeared.
To address this ecological crisis, the Comprehensive Everglades Restoration Plan (CERP) was authorized in 2000. A primary goal of this multi-decade, multi-billion dollar project is to restore the natural sheet flow. Key projects involve removing barriers and backfilling canals. One significant step has been the modification of the Tamiami Trail, a highway built in the 1920s that acted as a dam. The construction of 3.5 miles of bridging now allows significantly more water to flow south into Everglades National Park, an important effort to rehydrate the "River of Grass."