The Ngorongoro Conservation Area (NCA) is a conservation area and a UNESCO World Heritage Site located 180 km (110 mi) west of Arusha in the Crater Highlands area of Tanzania. The area is named after Ngorongoro Crater, a large volcanic caldera within the area. The conservation area is administered by the Ngorongoro Conservation Area Authority, an arm of the Tanzanian government, and its boundaries follow the boundary of the Ngorongoro Division of the Arusha Region.
The Munge Stream drains Olmoti Crater to the north, and is the main water source draining into the seasonal salt lake in the center of the crater. This lake is known by two names: Makat as the Maasai called it, meaning salt; and Magadi. The Lerai Stream drains the humid forests to the south of the Crater, and it feeds the Lerai Forest on the crater floor - when there is enough rain, the Lerai drains into Lake Magadi as well. Extraction of water by lodges and NCA headquarters reduces the amount of water entering Lerai by around 25 percent.
The other major water source in the crater is the Ngoitokitok Spring, near the eastern crater wall. There is a picnic site here open to tourists and a huge swamp fed by the spring, and the area is inhabited by hippopotamus, elephants, lions, and many others. Many other small springs can be found around the crater's floor, and these are important water supplies for the animals and local Masaai, especially during times of drought.
Following the recommendations of the ad hoc committee of scientists convened after the year 2000 drought, an ecological burning program was implemented in the crater, which entails annual or biannual controlled burns of up to 20 percent of the grasslands. Maasai are now permitted to graze their cattle within the crater, but must enter and exit daily.
The Ngorongoro Conservation Area also protects Olduvai Gorge, situated in the plains area. It is considered to be the seat of humanity after the discovery of the earliest known specimens of the human genus, Homo habilis as well as early hominidae, such as Paranthropus boisei.
The Olduvai Gorge or Oldupai Gorge is a steep-sided ravine in the Great Rift Valley, which stretches along eastern Africa. Olduvai is in the eastern Serengeti Plains in northern Tanzania and is about 50 kilometres (31 mi) long. It lies in the rain shadow of the Ngorongoro highlands and is the driest part of the region. The gorge is named after 'Oldupaai', the Maasai word for the wild sisal plant, Sansevieria ehrenbergii.
Approximately 25,000 large animals, mostly ungulates, live in the crater. Large animals in the crater include the black rhinoceros (Diceros bicornis), the African buffalo or Cape buffalo (Syncerus caffer), and the hippopotamus (Hippopotamus amphibius). There also are many other ungulates: the blue wildebeest (Connochaetes taurinus) (7,000 estimated in 1994), Grant's zebra (Equus quagga boehmi) (4,000), the common eland (Taurotragus oryx), and Grant's (Nanger granti) and Thomson's gazelles (Eudorcas thomsonii) (3,000). Waterbucks (Kobus ellipsiprymnus) occur mainly near Lerai Forest. There are no topis (Damaliscus lunatus), oribis (Ourebia oribi), or crocodiles (Crocodylus niloticus). Impala (Aepyceros melampus) are absent because the open woodland they prefer does not exist. Giraffe also are absent, possibly because of a lack of browse species. Tanzanian cheetah (Acinonyx jubatus raineyii), East African wild dog (Lycaon pictus lupinus), and African leopard (Panthera pardus pardus) are rarely seen