Stream Health - Water Chemistry
Chemical monitoring provides additional insight into the quality of water every time a site is visited. Occasionally, it is possible to detect a pollution event in a stream by taking note of pH, conductivity, temperature, and/or dissolved oxygen. After noting an abnormal reading, it is sometimes possible to walk upstream to investigate a potential pollution source.
Physical Chemistry
Data Collected at all stream monitoring sites
pH represents the acidity level in the water. If this is out of balance, stream wildlife can suffer.
The temperature of the water is very important aquatic life. If it gets too warm, sensitive species can die.
Dissolved Oxygen measures the amount of oxygen in the water that is available to biological life, including benthic macroinvertebrates and fish.
Measuring air temperature helps to determine the conditions of the day when monitoring is taking place. It can help our biologists better understand the data.
Measuring conductivity is particularly important as it can indicate if pollution has entered the water. Elevated levels can mean it is unsuitable for sensitive wildlife.
The County is working to establish additional physical monitoring including procedures for bacteria, and PCBs. Several local watershed groups have received grants through the water quality protection fund to monitor bacteria in the County. Learn more about these projects: Anacostia, Potomac Riverkeeper, Little Falls)
If pollution is found but its source is not initially able to be detected, the County’s compliance team is called in to conduct an Illicit Discharge Detection and Elimination investigation (IDDE) which is designed to detect and manage illicit discharges and stormwater runoff. IDDE is a requirement in the County’s MS4 permit.
Illicit discharges can involve materials such as dumped oils, fats and grease into a storm drain, liquid draining from trash dumpsters, chemicals, paint, dyes or other hazardous materials being discharged, intentionally or unintentionally, into the stormwater sewer system.
DEP is required to identify outfalls, or the opening of the end of pipes within a storm drain system, that have flowing water when it has not rained within the last 72 hours. This is considered dry-weather flow, and is generally a warning sign of a potential illicit discharge. Once identified, the water is tested to isolate a source. Once a source is determined, whether a business or a homeowner, appropriate actions are taken to stop the discharge and ensure proper clean up.
DEP relies on watchful citizens to help identify any illegal discharges, dumping, or spills! If you notice any spill or discharge of a suspected hazardous or harmful nature, please notify 311 immediately.