The City's Stormwater Management Division monitors the following chemical and physical parameters in Greensboro surface water:
Fecal Coliform Bacteria: Fecal coliform bacteria, caused by animal waste runoff, septic systems, sewer overflows, and point discharges of water from wastewater treatment plants, frequently have an adverse effect on water resources. Their presence serves as a reliable indicator of bacterial contamination in water. There are, however, a number of FC bacteria that are commonly found living in the soil and on plants. FC also serves as an indicator of the public health threat from coming in contact with surface waters.
Total Suspended Solids (TSS): The weight of particles that are suspended in water accounts for the measurement of the total suspended solids. In the water column, solids reduce light penetration and can clog the gills of fish and invertebrates. TSS is often associated with toxic contaminants because organic materials and metals tend to bind to particles and stay suspended in the water column.
Total Dissolved Solids (TDS): Like TSS, the total dissolved solids measurement refers to the amount of particles in the water. Yet these are the filterable particles of matter. Though the water may appear to be clear of debris, waters with high dissolved solids generally are of inferior quality. The pollutants have dissolved into smaller particles within the water.
Heavy Metals: Heavy metals are among the most harmful of the elemental pollutants. Lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) are heavy metals associated with industrial discharges. The brake-pads on cars also contain some of these metals. Brake-pad discharges run off from roads into City streams. At higher concentrations, these heavy metals are toxic to plant and aquatic life in streams.
Nutrients: Nitrogen and phosphorus are chemicals that plants and animals need for growth. Excessive amounts of nutrients can degrade water quality by promoting excessive growth, accumulation, and subsequent decay of plants, especially algae. These nutrients result from runoff from fertilizer use, leaching from septic tanks and sewage, and the erosion of natural deposits. Some nutrients can be toxic to animals at high concentrations. Parameters measured by Stormwater Services include ammonia-nitrogen (NH3-N), nitrate (NO3-N), nitrite (NO2-N), total kjeldahl nitrogen (TKN) and total phosphorus (TP).
Turbidity: Turbidity is a measure of the clarity of the water. Turbidity may be caused by a wide variety of suspended materials, which is a major determinant of the quality and productivity of that stream system. Cloudiness in water is caused by the presence of suspended particles such as clay and silt.
Temperature: The temperature of a body of water directly and indirectly affects several physical, chemical, and biological components of water. For example, the dissolved oxygen concentration is inversely related to temperature. Runoff from urban areas tends to be warmer than runoff from undeveloped areas. Pavement and concrete in developed areas rapidly gain heat, warming runoff that flows over them. The stream channels in developed areas typically have fewer trees to shade the water, causing even more heating. These increased temperatures cause biological impairment in streams.
Alkalinity: Alkalinity is a measure of the buffering capacity of surface water, or the ability of water to cushion its components, which is important to water quality. It is the capacity of the water to accept positive hydrogen ions, such as carbonate, hydroxide, bicarbonate and other bases, that tends to elevate the water’s pH to a level above 4.5.
pH: A scale based on the hydrogen ion concentration by which water and other substances are measured to determine if they are acidic, neutral, or alkaline (basic). The midpoint of the scale is pH 7.0 or neutral. Readings from 0.0 to 7.0 are acidic and the lower the pH value the more strongly acidic the material. Readings from 7.0 to 14.0 are alkaline (basic) and the higher the reading the more strongly alkaline (basic) the material. Rapid increases in pH can cause ammonia (NH3) concentrations to increase to concentration levels that are toxic to aquatic organisms.
Conductivity: Conductivity is a measure of the ability of a body of water to carry an electrical current. This ability is dependent on the presence of dissolved ions, their total concentration, mobility, valence, and relative concentrations in the water temperature. In general, as the pollutant load to natural water increases, the concentration of dissolved ions increases. High conductivity values generally indicate high levels of pollution.
Biochemical Oxygen Demand (BOD): Oxygen is not only required for survival of most living organisms, but is needed to decompose organic material. Organic materials accumulate in bottom sediments and support microorganisms, including bacteria, which consume oxygen as they break down the materials. The amount of oxygen required for the decomposition of organic material and the oxidation of chemicals in the water during the storage period, is a measurement known as the BOD.
Chemical Oxygen Demand (COD): Like the BOD, the COD also refers to the amount of oxygen used during oxidization (the breakdown of materials using oxygen). The chemical oxygen demand refers to both the organic matter and the inorganic oxidizing matter found in bottom sediments of a stream. It is also referred to as the oxygen consumed.
Dissolved Oxygen (DO): DO is a measure of the concentration of dissolved oxygen present in a body of water. DO is an important measure of water quality and the ability of surface waters to support a well-balanced aquatic ecosystem.