Water Quality Index

The Water Quality Index (WQI) is based on whether water quality data meets Texas Surface Water Quality Standards. The standards are written by the Texas Commission on Environmental Quality, with guidance provided by the U.S. Environmental Protection Agency and under the authority of the federal Clean Water Act and Texas Water Code. The standards generally consider three water uses: aquatic life, recreation and domestic water supply.

Water Quality Index map
San Saba River Lake Buchanan Llano River Inks Lake Lake Marble Falls Lake Travis Lake LBJ Austin Pedernales River Bastrop Smithville La Grange Columbus Wharton Bay City

The list of parameters used to produce the WQI include: dissolved oxygen, pH, temperature, E. coli bacteria and total dissolved solids calculated from specific conductivity. Data are provided by Colorado River Watch Network volunteers and LCRA staff.

Important points about the WQI:

  • This is not a swimming index. Regardless of whether the standard was met, there is always a chance that microbes in the water may cause infections. Swimming in any river, lake or pond carries some risk. Be aware of inherent risks and take appropriate precautions at all times.
  • Data used for the WQI are representative of conditions at the time samples were collected. Conditions may have changed by the time samples were analyzed and results were reported. Rainfall runoff, for example, will affect WQI parameters.