Water Resource Division

Calhoun Canal System

This System is part of the Water Resources Division and is headquartered with other GBRA operations in Calhoun County. 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 GBRA Port Lavaca Water Treatment Plant or used in various industrial processes by petrochemical facilities operated by Seadrift Coke, INEOS Nitriles and the Dow Chemical Company near Seadrift, Texas. A large volume of water is also delivered to agricultural users, primarily for rice irrigation but also including row crop, pasture, aqua-culture and waterfowl operations. The operation and maintenance of approximately 75 miles of canals is required for delivery to customers. Although most of the water is delivered during the spring and summer growing season, year-round deliveries are necessary due to the variety of needs and scheduling for all customers.

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 located at river mile 10 are working properly. This ensures watercourse stability and safe boating access, and allows a more efficient diversion of water for beneficial use. Because the dam operates under low head settings, much if not 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.

Daily monitoring and testing of raw water quality is performed by the Division staff. Routine billing of raw water customers and contract administration services are performed at the area office, in close coordination with GBRA staff in Seguin.

Canyon Dam and Reservoir

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 operates the water storage portion to provide municipal, industrial, and agricultural customers with a dependable water supply during drought or low flow conditions.

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.

Primarily, the reservoir provides flood control protection for people living downstream of the Dam, but it also supplies many users with their sole source of water. For others, it provides a dependable alternative source of water during drought conditions and low river flows. Reservoir water supplies stored water to cities, industries and agricultural users. Under a permit issued by the State of Texas, GBRA is allowed to divert an average of 90,000 acre-feet per year of stored water to supply contracted water users.

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.


The GBRA Lab provides support services for GBRA-operated water and wastewater plants, chemical and bacteriological testing for cities, water districts, industries, consulting firms, and private individuals, and environmental monitoring within the river basin.

The laboratory conducts chemical and bacteriological analysis of of potable water, wastewater and environmental samples utilizing current technology and equipment, including a Perkin-Elmer 5100ZL Graphite Furnace/Flame Atomic Absorption Unit to test water for the presence of lead and 14 other heavy metals.

In addition to its broad water quality planning initiatives and participation in environmental and water quality monitoring programs within the river basin, the laboratory also sponsors and trains Texas Watch water quality monitors, a statewide volunteer program created under the Texas Clean Rivers Act of 1994 to involve citizens in the testing and protection of water resources. The lab also conducts presentations for schools, civic and other organizations on water quality, environmental issues, Texas Watch and other water-related subjects.

The laboratory maintains strong working relationships with federal, state and local government agencies responsible for water quality, as well as corporations and individuals capable of affecting water quality.

© 1998 Guadalupe-Blanco River Authority