It is bounded by two dams and is identified by the State of Texas Water Quality Inventory as Segment 1429 of the Colorado River Basin. The total drainage area of Town Lake is approximately 158 square miles. This area is divided into nine watersheds formed around nine major tributary creeks. Map 1 below is a satellite image of the area under observation. Town Lake is the waterway in the middle of the picture.
White color indicates the highest level of urban development.
While Town Lake is over-urbanized it still is a habitat for numerous plants and wildlife. As is the case with urban waterways throughout the United States, Town Lake is highly susceptible to pollution. Pollution sources include storm water run off, effluents from sewage systems, and other sources associated with high levels of development and urbanization. Austin is undergoing rapid growth. In 1996, the number of people with treated wastewater was 548,043.