Colorado City Reservoir - 2016 Survey Report

Prepared by Lynn Wright
Inland Fisheries Division
San Angelo District

This is the author's summary from a 19-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Colorado City Reservoir were surveyed in 2017 using electrofishing and gill netting. This report summarizes the results of the surveys and contains a management plan for the reservoir based on those findings.

Reservoir Description

Colorado City Reservoir is a 1,618-acre reservoir located on Morgan Creek, a tributary of the Colorado River, west of Colorado City in Mitchell County, Texas. Habitat consisted primarily of flooded terrestrial vegetation, boulders, and boat docks. The Morgan Creek Power Plant, that used Colorado City as a cooling reservoir, ceased operating in 2008. Since then, the reservoir water level was not maintained at a near-constant level, as it had been in the past. Colorado City Reservoir has been severely impacted by toxic golden algae (Prymnesium parvum) blooms nearly every year since 2001 with fish kills occurring regularly. Shoreline access was good, including at the Lake Colorado City State Park, but boat access was not possible from 2011-2016 due to low water level. Boater access became available at the state park ramp after heavy rains in November 2016 increased water level.

Management History

Historically, important sport fish included Largemouth Bass, White Bass, Channel Catfish, Blue Catfish, and Red Drum. Following golden algae-induced fish kills, fish stockings were conducted to reestablish populations. Florida Largemouth Bass (603,683) and Bluegill (863,965) were stocked during 2004-2008 and Channel Catfish (1,054,326) during 2003-2008. Re-occurrence of golden alga-related toxic conditions rendered these stocking efforts unsuccessful at re-building populations. As a result, all fish stocking in this reservoir has been suspended pending sustained improvements in water quality.

Fish Community

• Prey species: Gizzard Shad and Bluegill were not collected during sampling. Green Sunfish and killifish spp. were present in the reservoir.
• Catfishes: No Channel Catfish were collected during sampling.
• White Bass: No White Bass were collected during sampling.
• Largemouth Bass: Largemouth Bass were present, but only one fish was collected.
• White Crappie: No White Crappie were collected during sampling.

Management Strategies

Continue to monitor for golden algae during fall, winter, and spring quarters. Stock prey species if non-toxic conditions persist for two consecutive years and stock sportfish if non-toxic conditions persist for three consecutive years. Conduct electrofishing in 2020 and gill netting in 2021.

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