Dallas Water Utilities (DWU) is leading the city’s surface water quality monitoring efforts with a focus on public health and environmental protection. For over 20 years, the City of Dallas has monitored local waterways to ensure safe recreational use for residents. This long-term commitment has led to the development of various programs to assess and manage water quality in rivers, creeks and streams, adapting over time to meet regulatory changes and increased environmental awareness.
DWU’s monitoring programs include dry weather screening, wet weather screening, rapid bioassessment and adherence to Total Maximum Daily Load (TMDL) regulations. The dry weather screening program targets and eliminates illegal discharges into Dallas waterways, with nearly 1,300 outfalls inspected annually.
The wet weather screening program focuses on identifying pollutant levels in stormwater runoff that occur during rain events. Quarterly data collection from 24 sites helps track regional water quality trends, while biannual data from 14 sites ensures compliance with Texas Commission on Environmental Quality (TCEQ) standards. After rainstorms, runoff can elevate E. coli levels by washing pollutants, such as trash and animal waste, into waterways. The rapid bioassessment program evaluates the chemical, physical and biological health of local water bodies. Every year, water quality samples are collected and analyzed from 72 different locations throughout the city. In addition, macroinvertebrates (aquatic insects) are collected and identified to determine the longer-term effect on water quality.
DWU utilizes bacterial source tracking (BST) to pinpoint contamination sources of E. coli bacteria, such as humans, wildlife or livestock. DNA found in E. coli bacteria samples is compared with an extensive DNA library to determine who or what produced the bacteria since E. coli is present in the intestines of all humans and warm-blooded animals. Texas A&M AgriLife, which has the largest catalog of DNA samples specific to Texas wildlife, matches the DNA found in the E. coli samples with the library data. After analyzing the results, DWU can determine if the source is from domesticated animals or livestock, wildlife or humans.
Federal and state surface water quality regulations differ from that of drinking water and guide DWU’s surface water quality management. Different rules apply depending on how the water is used. The Clean Water Act (CWA) is in place for creeks, streams and lakes – waterways used for drainage and recreation, not drinking water sources. The CWA allows for some level of bacteria in these waterways. The Safe Drinking Water Act, including the Revised Total Coliform Rule, mandates much stricter standards for drinking water from your faucet, requiring it to be free of coliform bacteria like E. coli.
For freshwater recreation, Texas Surface Water Quality Standards set a geometric mean limit for E. coli of 126 bacteria per 100 milliliters (mL) of water and a single-sample limit of 399 bacteria per 100 mL. Dallas residents are encouraged to take precautions in local waterways, especially after rainstorms when bacterial levels can spike. Swimming in creeks is generally prohibited and residents should practice good hygiene by washing their hands after coming into contact with creek water.
DWU’s dedication to water quality ensures that Dallas’ waterways remain safe and enjoyable for residents. By providing safe recreational opportunities and managing environmental health proactively, DWU helps Dallas maintain its waterways as valuable resources for the community’s well-being and quality of life.