Because over 80% of Guyana is still wilderness, the country has so far sustained little serious environmental damage. The air is clean, but water supplies are threatened by sewage and by agricultural and industrial chemicals. One potential problem for the nation's water supply is the pollution of its wells by salt water from the ocean. Guyana has 241 cu km of renewable water resources with 98% used for farming purposes. About 98% of the nation's city dwellers and 91% of people living in the rural areas have access to safe drinking water. The nation's cities produce over 0.1 million tons of solid waste per year. Since 1985, the nation has experienced an increase in diseases related to water and food consumption. Kaieteur National Park is the only specifically designated conservation area. In 2001, 10 of Guyana's 193 mammal species and 3 of its 678 breeding bird species were endangered. Eight types of reptiles were also endangered. Fifty-four of Guyana's 6,000-plus plant species were threatened with extinction. Endangered species in Guyana include the tundra peregrine falcon, the black caiman, and four species of turtle (green sea, hawksbill, olive ridley, and leatherback).