From there the water flows by gravity through the rest of the Main Aqueduct. One branch line called the East Aqueduct, serves Borger and Pampa with a combination of gravity and pumped flow. A second branch, the Southwest Aqueduct, goes west from Lubbock to Levelland and then south to Brownfield. Pumping is required from Lubbock to Levelland, and the water flows by gravity from Levelland to Brownfield. Regulating reservoirs located at Amarillo, Lubbock, and Borger allow the cities to receive water even when the pumping plants are shut off.
Cities are responsible for the treatment of the water.
Amarillo, Borger, Pampa, and Plainview have individual treatment plants. A joint plant operated by Lubbock treats all of the water for the seven southern cities. Since beginning operation in 1968, the Authority has supplied up to 70 percent of the total water used by the member cities.