Stillhouse Hollow Reservoir - 2021 Survey Report

Prepared by John Tibbs and Michael S. Baird
Inland Fisheries Division
Waco District

This is the authors' summary from a 28-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Stillhouse Hollow Reservoir were surveyed with fall electrofishing in 2021; scheduled spring gill netting was not conducted in 2022 due to widespread coverage of Hydrilla. Historical data are presented with the 2021 data for comparison. This report summarizes the results of that survey and contains a management plan for the reservoir based on those findings

Reservoir Description

Stillhouse Hollow Reservoir is a 6,430-acre reservoir located in Bell County, Texas. The impoundment was created in 1968 and is operated by the United States Army Corps of Engineers (USACE). Primary water uses include flood control, municipal water supply and recreation. The reservoir is classified as oligotrophic and has a maximum depth of 107 feet. Water level was less than one foot below conservation pool (622 feet msl) during 2021 vegetation and electrofishing surveys. Fish habitat at the time of sampling consisted mainly of rock and limestone bluff shorelines, flooded timber and dead trees and stumps. Some native aquatic plants were present in low abundance and Hydrilla coverage was significant.

Management History

: Important sport fishes include Largemouth and Smallmouth Bass, Channel Catfish and White Bass. Sport fishes in Stillhouse Hollow Reservoir have always been managed with statewide regulations. Management plans from 2013/2014 included posting aquatic invasive species (AIS) signage at access points and partnering with the USACE to introduce native vegetation into the reservoir. Aquatic invasive species signage was posted at all access points during summer 2013 and zebra mussel outreach interns were hired in 2014 and 2015 to interface with boaters at Stillhouse Hollow ramps. Low water from 2014 to 2016 prevented native vegetation plantings from happening and the strategy was then discarded. More recently, management efforts have focused on maintaining AIS signage at access points, providing technical support and informational materials for the “Clean, Drain and Dry” campaign and making a speaking point about AIS during conversations and presentations with constituents. Additional recent efforts include using Brazos River Authority (BRA) funding to build and deploy fish attracting structures in the upper half of the reservoir, stocking and monitoring genetics of Largemouth Bass and collecting genetics of Spotted Bass to determine if any Guadalupe genetics are found in the reservoir. Management efforts from 2021-2022 include aquatic vegetation, boater access and electrofishing surveys.

Fish Community

• Prey species: Threadfin Shad were present in the reservoir. Electrofishing catch of Gizzard Shad was higher than the previous two surveys, and most were available as prey to sport fish. Electrofishing catch of Bluegill was high, and fish six inches and longer were more plentiful than in previous surveys. Redear and Longear Sunfish also contributed to the prey base.
• Channel Catfish: Channel Catfish were collected in modest numbers in 2018. Most exceeded 18 inches and were in good condition. Flathead Catfish were also present in the reservoir.
• Black basses: Largemouth Bass were abundant and body condition was fair across length classes. More legal-length fish were available to anglers than in the previous two surveys.
• White Bass: White Bass were collected in low numbers during the 2018 gill netting survey and were generally in poor body condition.

Management Strategies

• Continue managing Stillhouse Hollow Reservoir with existing regulations.
• Conduct monitoring surveys with fall electrofishing and spring gill netting in 2025 and 2026 respectively, and an additional gill netting survey in spring 2024 (Table 8). Conduct aquatic vegetation and access surveys in late summer 2025 (Table 8).
• Continue efforts to educate the public about AIS issues and protect the reservoir from zebra mussel introductions.
• Coordinate with the BRA on future artificial habitat projects pending funding and reservoir priorities.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-3 Statewide Freshwater Fisheries Monitoring and Management Program