Water Resource Management – 2

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Water Resource Management – 2

Coleto Creek Division

Coleto Reservoir System

This reservoir system stretches for 3,100 acres and collects natural watershed runoff and State permitted water diverted from the Guadalupe River The reservoir is managed by GBRA to provide cooling water to Coleto Creek Power’s adjacent electric generating plant at Fannin.

The Coleto reservoir system is monitored for shoreline pollution, and division staff educate the public on prevention techniques. The division also participates in an aquatic plant management program to control noxious aquatic vegetation.

Water Supplies

Combined with firm and other run of the river surface water rights and groundwater permits, GBRA has access to over ~300,000 acre-feet of water for raw water supplies.

Canyon Dam and Reservoir – 90,000 acre-feet

Completed in 1964, this cooperative project between the U.S. Army Corps of Engineers and GBRA provides flood control protection and a stored water supply.

GBRA is responsible for reservoir water management and release within the ‘conservation pool,’ between 800 feet mean sea level (msl) and the normal operating elevation of 909 msl. The Corps is responsible for management and release of waters within the ‘flood control pool’ at elevations of 909 to 943 msl. Water is normally released as soon as possible from this portion of the reservoir which must be kept empty to contain runoff from high rainfall and flood events.

The dam is an earthfill embankment, 224 feet high and 6,830 feet long. At maximum ‘conservation pool’ level of 909 feet elevation msl, the reservoir covers more than 8,200 surface acres and impounds 386,200 acre-feet of water to a depth of 140 feet. At maximum ‘flood control pool’ elevation of 943 feet msl, the reservoir impounds a total of 732,600 acre-feet of water.

Luling (San Marcos River) – 4,572 acre-feet

This water right is located in the San Marcos River and supplies the cities of Luling and Lockhart. The river intake pump sends water to the Luling WTP which is owned and operated by GBRA.

Calhoun Canal System – 172,501 acre-feet

Utilizing permits granted by the state of Texas, the system delivers water from the Guadalupe River near Tivoli into the GBRA diversion and canal network for distribution to industrial, municipal, and agricultural customers in Calhoun County through a series of irrigations canals, checks, pump stations and pipelines.

The raw water supply is processed into treated drinking water by the Undine Port Lavaca Water Treatment Plant or used in various industrial processes by petrochemical facilities. In times of drought and low river flows, water deliveries only include contracted firm water supply municipal and industrial customers.

Salt Water Barrier. Continuous operating and maintenance activities are performed on the lower stretch of the Guadalupe River to remove log jams and to ensure the Lower Guadalupe Diversion Dam and Salt Water Barrier structures are working properly. Because the dam operates under low head settings, most of the water will flow over the fabridam bags and into the bay and estuary system. In times of extreme drought, the fabridam can protect the fresh water supply from tidal salt water intrusion. GBRA also serves as an observer for the U.S. Geological Survey Guadalupe River data collection project.

Carrizo Groundwater Supply Project – 24,000 acre-feet

Starting in 2024, the first phase of the Carrizo Groundwater Supply Project will bring 15,000 acre-feet online from a GBRA groundwater permit and 5,000 AF from an Alliance Regional Water Authority (ARWA) permit sourced by the Carrizo Aquifer in Gonzales and Caldwell counties. GBRA will add an additional 9,000 AF of groundwater to phase two of the project and ARWA will add 10,000 AF, which is set to be completed by 2028.