The dense tropical rain forests that once covered much of the country are now found only along the river valleys and in isolated pockets of the Atakora Mountains. Slash-and-burn agriculture and the cutting of wood for fuel are the major causes of forest depletion. Between 1990 and 1995, Togo lost an average of 1.44% of its forest and woodland each year. Soils are generally of poor quality, requiring intensive fertilization and cultivation to be productive. The soil and water supply are threatened by pesticides and fertilizers. The nation's land is also threatened by desertification. Water pollution is a significant problem in Togo, where only 85% of urban dwellers and 38% of the people living in rural areas have pure drinking water. Contamination of the water supply contributes to the spread of disease. Responsibility in environmental matters is vested in the Ministry of Rural Development and the Ministry of Environment and Tourism. The government of Togo has tried to protect the nation's environment through a comprehensive legislative package, the Environmental Code of 1988. The nation's wildlife population is at risk due to poaching and the clearing of land for agricultural purposes. As of 2001, 7.6% of Togo's total land area was protected. Eight mammal species and one bird species are listed as threatened. Threatened species include the African elephant, Diana monkey, and West African manatee.