Granger Reservoir 2020 Survey Report media download(PDF 921.5 KB)

If you have difficulty accessing the information in this document, contact the TPWD Inland Fisheries Division for assistance.


Granger Reservoir - 2020 Survey Report

Prepared by Muhktar Farooqi and Patrick Ireland
Inland Fisheries Division
San Marcos/Austin District

This is the authors' summary from a 33-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Granger Reservoir were surveyed in 2020 using electrofishing, trap netting and in 2021 using gill netting. Historical data are presented with the 2017-2021 data for comparison. This report summarizes the results of the surveys and contains a management plan for the reservoir based on those findings.

Reservoir Description

Granger Reservoir is a 4,009-acre impoundment of the San Gabriel River in Williamson County, Texas. The reservoir is located approximately 40 miles northeast of Austin, Texas, within the Brazos River drainage basin. It was constructed in 1980 by the U. S. Army Corps of Engineers (USACE) for purposes of flood control and water conservation. Granger Reservoir has a drainage area of approximately 709 square miles and a shoreline length of about 29 miles. High turbidity and fluctuating water levels have deterred the establishment of aquatic vegetation in the past. Reservoir bank slope is relatively flat and small changes in water level (1-2 feet) can have a large impact on the abundance of shoreline habitat and river/reservoir connectivity. Granger Reservoir was classified as “infested” with zebra mussels in December 2019.

Management History

Important sport fish include White Crappie, White Bass, and Blue Catfish. The last creel survey was conducted in the spring of 2005 and showed White Crappie was the most sought-after species (61.5% directed angler effort) followed by catfishes (16.8%), White Bass (5.1%), and Largemouth Bass (2.5%; Bonds and Magnelia 2005). Blue Catfish were stocked in 1995 and 1996 to provide additional angling opportunities and utilize an abundant shad population. No additional stocking has been conducted since 1996. In collaboration with the Brazos River Authority (BRA), a fishery assessment (habitat availability, river/reservoir connectivity, and access at various lake levels) was conducted at Granger Reservoir for a multi-year system operating plan for the Brazos River Basin (Farooqi and De Jesus 2013). Based on these multiple assessments, threshold recommendations were provided to decrease potential impacts to the fishery during future basin-wide water level manipulations. The Granger Reservoir management threshold recommendation was 504 ft. above mean sea level (MSL), which is the same as conservation pool. A critical threshold for fisheries applications was set at 498 ft. MSL. As a consequence, other than under exceptional circumstances, water level fluctuations at Granger Reservoir will be minimal and therefore have little impact on the fishery. Low to negligible vegetative coverage has been descriptive of Granger Reservoir.

Fish Community

Management Strategies

Sport Fish Restoration Logo

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-2 Inland Fisheries Division Monitoring and Management Program

Related Links: