Question: Keith County, Nebraska is located over what 174000 sq mi aquifer?
Context: Sucia Island is located 2.5 mi north of Orcas Island in the San Juan Islands, San Juan County, Washington, United States.  It is the largest of an archipelago of ten islands including Sucia Island, Little Sucia, Ewing, Justice, Herndon, the Cluster Islands islets, and several smaller, unnamed islands.  The group of islands is about 2.5 mi in length and just short of a half mile wide.  Sucia island is roughly the shape of a hand.  The total land area of all islands is 2.74 km² (1.058 sq mi, or 677 acres).  The main island of Sucia Island by itself is 2.259 km² (0.8722 sq mi, or 558.1 ac).  There was a permanent population of four persons as of the 2000 census, all on Sucia Island.  Sucia Island State Park is a Washington State Marine Park. Clearwater County is a municipal district in west central Alberta, Canada in Division No. 9.  Its northwest boundary is the Brazeau River.  The municipal office is located in the Town of Rocky Mountain House.  The county has a land area of 18,691.65 km² (7,216.89 sq mi) and comprises close to 99% of Census Division No. 9's land area of 18,921.38 km² (7,305.59 sq mi).  Although the territory excluded is rather small in geographical area, it comprises the major population centre of Rocky Mountain House, which has one-third of Division No. 9's population, in addition to the communities of Caroline, Burnstick Lake and three Indian reserves.  The county's 2016 census population was 11,947. Colville Lake is the 20th largest lake in Canada's Northwest Territories.  The lake is located 100 km (62 mi) northwest of Great Bear Lake in the Sahtu Region.  The lake has a perimeter of 121 km (75 mi) and a net area of 416 km² (161 sq mi) and a total area of 439 km² (169 sq mi). Lemoyne is an unincorporated community and census-designated place in northern Keith County, Nebraska, United States.  It lies along Nebraska Highway 92 on the northern shore of Lake C.W. McConaughy, north of the city of Ogallala, the county seat of Keith County.  Its elevation is 3,333 feet (1,016 m).  Although Lemoyne is unincorporated, it has a post office, with the ZIP code of 69146. Kingsley Dam is located on the east side of Lake McConaughy in central Keith County, Nebraska, and is the second largest hydraulic fill dam in the world.  It was built as part of the New Deal project.  The dam is 162 ft tall, 3.1 mi long, and 1100 ft wide at its base.  On the east side of the dam is Lake Ogallala and on the south side is the Kingsley Hydroelectricity Plant.  The Nebraska Game and Parks Commission and Central Nebraska Public Power and Irrigation District are also located in this area.  Kingsley Dam, the Kingsley Hydroelectricity Plant, the Morning Glory Spillway, and the Outlet Tower – a large structure near the dam used to release water from the lake – are main visual icons of Lake McConaughy. Ogallala is a city in Keith County, Nebraska, United States.  The population was 4,737 at the 2010 census.  It is the county seat of Keith County.  In the days of the Nebraska Territory, the city was a stop on the Pony Express and later along the transcontinental railroad.  The Ogallala Aquifer was named after the city. The Ogallala Aquifer is a shallow water table aquifer surrounded by sand, silt, clay and gravel located beneath the Great Plains in the United States.  One of the world's largest aquifers, it underlies an area of approximately 174000 sqmi in portions of eight states (South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico, and Texas).  It was named in 1898 by geologist N. H. Darton from its type locality near the town of Ogallala, Nebraska.  The aquifer is part of the High Plains Aquifer System, and rests on the Ogallala Formation, which is the principal geologic unit underlying 80% of the High Plains. The Luzon rainforest is a moist broadleaf forest that contains the lowlands (below 1000 m) of Luzon and the montane rainforests located on a several volcanic and non-volcanic mountains of the island.  The rainforest encompasses about 95,571 square kilometers (36,900 sq mi) out of the 109,965 sq kilometers (42,458 sq mi) of total area of the island of Luzon.  Luzon is the largest and most northern island of the Philippines, located in the western Pacific Ocean.  Though it is the most extensive rainforest ecoregion of the Philippines, very little of the original rainforest remains.  Considered a part of the Luzon rainforest ecoregion are the Batanes and Babuyan Islands to the north, Catanduanes and Polillo Islands to the east, and Marinduque to the southwest.  The status of this area is critical/endangered. Bath is a town in Steuben County, New York, United States.  The Town of Bath has an area of 96.3 sq mi (249 km2) and a population of 12,097 (in 2000).  Its largest settlement is the Village of Bath, which has an area of 2.9 sq mi (7.5 km2) and a population of 5,641 (in 2000).  The Town is located in the central part of the county, northwest of Elmira, New York.  The Town (and Village) are either named after the city in England or after Lady Bath, daughter of a landowner. Keystone is an unincorporated community and census-designated place in central Keith County, Nebraska, United States.  It lies along local roads near the North Platte River, northeast of the city of Ogallala, the county seat of Keith County.  Its elevation is 3,100 feet (945 m).  Although Keystone is unincorporated, it has a post office, with the ZIP code of 69144.
Answer: Ogallala Aquifer