I read it as "Ogallala"
Ogallala Aquifer
One of the world's largest aquifers, it covers an area of approximately 174,000 mi² (450,000 km²) in portions of the eight states of South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico, and Texas. It was named in 1898 by N.H. Darton from its type locality near the town of Ogallala, Nebraska.[1]
About 27 percent of the irrigated land in the United States overlies this aquifer system, which yields about 30 percent of the nation's ground water used for irrigation. In addition, the aquifer system provides drinking water to 82 percent of the people who live within the aquifer boundary
The USGS estimated that total water storage was about 2,925 million acre feet (3,608 km³) in 2005. This is a decline of about 253 million acre feet (312 km³) (or 9%) since substantial ground-water irrigation development began, in the 1950s.[5]
Water conservation practices (terracing and crop rotation), more efficient irrigation methods (center pivot and drip), and simply reduced area under irrigation have helped to slow depletion of the aquifer, but levels are generally still dropping. See the figure above for an illustration of the places where large drops in water level have been observed (i.e., the brown areas in southwest Kansas, and in or near the Texas panhandle). In the more humid areas, such as eastern and central Nebraska and south of Lubbock, water levels have risen since 1980.