Almost all of the water consumed in the Coastal Bend comes from rivers and reservoirs that form a regional water supply system. This surface water system consists of Lake Corpus Christi, Choke Canyon Reservoir, the Calallen Pool, Lake Texana and water from the Colorado River intake near Bay City.
Water stored in Choke Canyon and Lake Corpus Christi is released as needed and flows down the Nueces River into the Calallen Pool, a shallow reservoir formed by the Calallen Saltwater Barrier Dam alongside Interstate 37. The San Patricio Municipal Water District Edwards Pump Station takes water from the pool and pumps it to District facilities between Gregory and Ingleside.
Water from the Navidad River is stored in Lake Texana near Edna. It is carried to the Coastal Bend through the 64-inch Mary Rhodes Pipeline Phase 1 which runs from the Palmetto Bend Dam to Corpus Christi. It covers 100 miles and was completed in 1998. In 2000 the San Patricio Municipal Water District completed the Gene Dressen Pipeline, a 36-inch and 42-inch 
line which connects to the Mary Rhodes Pipeline south of Sinton and carries Lake Texana and Colorado River water to the District’s treatment complex.
Water from the Nueces River and from the Mary Rhodes Pipeline is blended before treatment to achieve optimal drinking water quality..
The three major reservoirs are operated in a managed system to maximize available water supplies and water quality while at the same time addressing the requirements for freshwater inflows into the Nueces Estuary and Lavaca Bay.
NUECES BASIN
Water pumped from the Nueces originates as rainfall runoff over the relatively arid watersheds of the Nueces, Atascosa and Frio Rivers. Water is stored in Choke Canyon Reservoir on the Frio River and in Lake Corpus Christi on the main stem of the Lower Nueces. Choke Canyon is a large reservoir completed in 1982 covering a surface area of 25,989 acres in Live Oak and McMullen Counties. It has a maximum elevation of 220.5 feet above sea level and can store up to 695,000 acre-feet of water. Water flows downstream from Choke Canyon into Lake Corpus Christi behind Wesley Seale Dam which was completed in 1958. It has a maximum elevation of 94 feet above sea level and can store up to 257,000 acre-feet of water, just 37% of the capacity of the larger, deeper lake upstream. The first dam at Lake Corpus Christi was built in 1929 with a maximum elevation of 74 feet above sea level. It failed a year later and was rebuilt in 1934.
LAVACA-NAVIDAD BASIN
The Navidad River watershed upstream from Lake Texana experiences considerably higher rainfall rates than the Brush Country that covers the Nueces Basin. This means that Lake Texana is generally a very reliable source of high quality water for the San Patricio Municipal Water District.
COLORADO RIVER BASIN
In 1998 the City of Corpus Christi, acting as the manager of the regional water supply system, purchased a portion of the water right in the Colorado River from the Garwood Irrigation Company. To deliver the Colorado River water to customers in the Coastal Bend required extension of the Mary Rhodes Pipeline. The 41-mile Phase 2 pipeline runs from near Bay City to the Lake Texana Pump Station was completed in 2016. More information about construction of Phase 2 is provided HERE.and HERE.
