How is the information generated?
Water quality professionals from throughout the Colorado River basin collect the data and enter it into a central database. The information comes from LCRA, the Colorado River Municipal Water District, the Upper Colorado River Authority, the Texas Commission on Environmental Quality, and the City of Austin.
TCEQ contracts with LCRA to collect and distribute the information as part of the Clean Rivers Program in the Colorado River basin. See LCRA's Clean Rivers Program for more information.
How many water-quality parameters are measured?
Several hundred parameters are monitored — everything from alkalinity and arsenic to water temperature and zinc. Each factor is referenced by a "parameter code."
Not all parameters are measured at every site. Areas with high populations or special considerations, like endangered species, often have more parameters measured than remote areas.
How can I tell if a water body is polluted?
It depends on what the water is used for — drinking, swimming, etc. For example, heavy rain can increase runoff and bacteria levels, making swimming unsafe.
TCEQ enforces water quality standards. Water bodies are evaluated by use (aquatic life, recreation, etc.) and given acceptable ranges for key measurements.
Water bodies not meeting standards are added to the 303(d) List. See the TCEQ site for more details.
What are the most common measures of water quality?
- pH: Measures acidity. 7 is neutral. Below 7 is acidic.
- Water temperature: Affects organisms, oxygen levels, and industry use.
- Turbidity: Measures cloudiness. Reported in NTUs.
- Dissolved oxygen: Important for aquatic life. Low levels = concern.
- Nutrients: Includes nitrogen, phosphorus, etc. Can cause overgrowth.
- Bacteria: E. coli and fecal coliforms indicate contamination.
- Toxic substances: Includes metals like lead and arsenic, plus pesticides.
Other variables include recent rainfall, water flow, and environmental conditions.
For terminology, visit the Water Quality Association glossary. For procedures, see the TCEQ Surface Water Quality Manual.
How often is the data collected?
It varies by site. Some locations are sampled every few weeks; others just a few times a year. Special events may trigger additional monitoring.
LCRA samples over 70 sites every other month.
Is the historic information important?
Yes. Water quality can fluctuate. A single measurement tells less than a trend over time. Historical data helps track changes and patterns.
What is a stream "segment"?
Segments are defined water bodies with similar characteristics. Each has a unique ID. They're the basis for applying site-specific standards and management plans.