The Everglades are unique; no other wetland system in the world is nourished primarily from the atmosphere.[5] Before the first attempt at draining the Everglades in 1882, the entire watershed extended from Orlando to Florida Bay comprising the Kissimmee–Lake Okeechobee–Everglades (KLOE) watershed. Kissimmee River outlets flow into Lake Okeechobee, which sits 18 feet (5.5 m) above sea level.[6] Only two seasons exist in the Everglades: wet (May to November) and dry (December to April). Average annual rainfall in the Everglades is approximately 62 inches (160 cm), though fluctuations of precipitation are normal.[7] Droughts, floods, and tropical storms are normal occurrences in the area.[8] When Lake Okeechobee exceeds its water storage capacity during the wet season, it pours slowly over the southern rim and flows for 100 miles (160 km) to Florida Bay. The gradient change is so slight that the river moves only 2 feet (0.61 m) a minute.[9] Sawgrass thrives in this river, dominates freshwater marshes and sloughs, and is the main characteristic of the region.