Wetlands were the first ecosystem to receive international attention through the "Convention on Wetlands of International Importance especially as Habitats for Waterfowls", opened for signature at Ramsar, Iran, in February 1971. The convention defines wetlands as: areas of marsh, fen, peat land or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six meters. These areas may incorporate riparian and coastal zones adjacent to the wetlands, and islands or bodies of marine water deeper than six meters at low tide lying within the wetlands.
Kenya has through the National Wetlands Standing Committee (NWSC) defined Kenyan wetlands as: “areas of land that are permanently seasonally or occasionally waterlogged with fresh, saline, brackish or marine waters at a depth not exceeding six meters, including both natural and man-made areas that support characteristic biota.”
Kenya has a variety of wetlands that stretch from coastal and marine wetlands to inland freshwater lakes, rivers, dams and swamps as well as the saline lakes of the Rift Valley system, constructed wetlands in the irrigation schemes, sewerage treatment systems and the mountain bogs, peat and glacier lakes. Some of these wetlands are recognized as important conservation areas such as National parks, National reserves, Ramsar sites, Important Bird Areas and World Heritage Sites.
There are five categories of natural wetlands that are generally recognized. They include;
1. Estuarine Wetlands: These wetlands are where fresh water and salt water mix. They include deltas, tidal marshes, and mangrove swamps
2. Marine Wetlands: These include coastal lagoons, rocky shores, and coral reefs
3. Riverine Wetlands: These are wetlands in the channels of rivers and streams
4. Lacustrine Wetlands: These are wetlands around lakes
5. Palustrine Wetlands: These include wet meadows, bogs, potholes and palayas.
The man-made wetlands include: Fish and shrimp ponds, Irrigated agricultural land, Salt pans, Reservoirs, Sewage farms and canals