Where does the water come from?
South Florida's freshwater comes from rain that falls in the Kissimmee Valley and southward. Average rainfall each year is between 40 to 65 inches! More than half of the rain occurs during Florida's wet season, June through September.
How did water flow in the past?
In the past, rainfall from the Kissimmee Valley filled Lake Okeechobee during Florida's summer rainy season and extra water would spill out of the Lake's southern shore. Some of the waters would sink into the soil nearby, changing decaying plants into rich, productive soils; and the rest were released to the beginning flows of the Everglade's "River of Grass".
The "River of Grass" was made up of shallow waters that were a few inches to a few feet deep and over 50 miles wide. These waters flowed 100 miles south across mostly sawgrass prairies to the Gulf of Mexico and Florida Bay (see picture at right).
What has changed about the water flow?
In 1926 and 1928, hurricane waters flooded Lake Okeechobee and caused the loss of many people's lives. This made the state of Florida ask for help from the U.S. Army Corp of Engineers (USACE). To control the waters and prevent flooding, the USACE built canals, gates, dams, pump stations and embankments (such as dikes and levees). Thousands of acres to the southeast of Lake Okeechobee were drained as an area for farming.
Man's control of the waters has replaced steady sheets of water that passed through the Everglades with times of drought (no water) or powerful discharges. Waters reaching the Everglades today have passed through agricultural and urban areas and contain increased nutrients, such as nitrogen and phosphorus, and pollutants.
Changes in the water flow have also resulted in habitat destruction and loss of species. Many animals are endangered or threatened and wading bird populations have been greatly reduced.
In 1999, a plan to restore Florida's ecosystem was presented to Congress. Today, the USGS (through the USGS South Florida Ecosystem Program) along with more than 30 other Federal, State, Local and Tribal government agencies are providing the scientific research needed to restore the South Florida environment.
U.S. Department of the Interior, U.S. Geological Survey, Center for Coastal Geology