Wildlife Habitat Appraisal for the Proposed Allens Creek Reservoir Site

Executive Summary

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This project was performed by the University of Houston Clear Lake during the months of May through August of 1995. It was executed under contract with Texas Parks and Wildlife Department (TPWD), Resource Protection Division. The purpose was to conduct a wildlife habitat appraisal of the proposed Allens Creek Reservoir (approximately 8,400 acres) located in Austin County south of Sealy and northeast of Wallis, Texas. Primary use of the land in the proposed reservoir has been for agricultural purposes since European settlement. Recent crops have been cotton, sorghum, corn, and soybeans. Cattle grazing also occurs throughout the project area.

The TPWD's Wildlife Habitat Appraisal Procedure (WHAP) was used in this project. To become familiar with the proposed Allens Creek Reservoir, information was obtained from U.S. Geological Survey 7.5 quad topographic map, high-altitude black and white aerial photographs, color infrared photographs, color photographs taken during fly-overs in light aircraft by team members, previous environmental impact studies by Houston Lighting and Power, and extensive ground-truthing augmented with a geographical positioning system (GPS). These information sources were used to determine boundaries of each cover type and location of the survey sites. A geographical information system (GIS) was used to create habitat coverages, boundaries, and types.

Grassy areas comprised the largest habitat type, followed by forests, cropland, and parks. Forests (bottomland and bluff) rated the highest habitat quality scores, followed by parks, grassy areas, and croplands. The forests scored high due to the greater diversity of woody and herbaceous species. Parks rated a moderate score having fewer woody species than the forested areas. Croplands scored low due to the nature of a monoculture.

The multiplicative product of two measurements (acreage and habitat quality score) resulted in the largest habitat units for forests, followed by grassy areas, croplands, and parks. The total habitat units and total potential loss of acreage due to construction of the reservoir will be 4,707 and 8,670, respectively. Mitigation requirements vary from 47,065 acres for an improvement of 0.10 in habitat quality of the mitigation property, to 5,229 acres for an improvement of 0.90 in habitat quality. No threatened or endangered plant or animal species were identified. There were no pronounced indicators of either wetland hydrology, vegetation, or soils. Yet all three were sufficient to demonstrate, at a minimum, the existence of jurisdictional wetlands in the lowest parts of the Brazoria clay depressions. Wetlands are conservatively estimated at 1,733 acres.