On this page you can learn about what Surface Water Standards are, and how they are used.
Water quality standards are state regulations or rules that protect lakes, rivers, streams and other surface water bodies from pollution. The rules are in Title 15A of the North Carolina Administrative Code (NCAC). These rules contain: beneficial use designations (classifications); numeric levels and narrative statements (water quality criteria) protective of the use designations; and procedures for applying the water quality criteria to wastewater dischargers and other sources of pollution.
Under the Clean Water Act, states are required to review their water quality standards and classifications every three years and make any modifications necessary to meet EPA guidance or protect waters of the state. This process is known as the Triennial Review. For more information on this process see the section titled Triennial Review.
Water quality standards are used to determine if the designated uses of a water body are being protected. Those uses are defined by the classifications (see the Classifications webpage for details) assigned to the water body. There may be more than one classification assigned to a water body and there may also be more than one standard that applies based on the classifications of a water body. For instance, for Class WS-II waters, the standard for Beryllium is 6.5 ug/l to protect aquatic life, 0.117 ug/l to protect human health from consumption of fish and shellfish and 0.0068 ug/l to protect human health from consumption of water, fish and shellfish. When trying to decide which standard to use, always take the lowest. So for this water, beryllium concentrations instream should not exceed 0.0068 ug/l to protect the most sensitive use - drinking water.
In permitting, the pollutants in water being discharged from a wastewater treatment facility are measured and their concentrations are compared to the surface water standard using a simple dilution equation. If the concentrations in the wastewater exceed or are expected to exceed the surface water standards, then the discharger is given a permit limit for the particular pollutant. Exceedances of the permit limit may result in fines and closure of the facility.
Surface water standards are also used to determine the status of a waterbody. Waters that are meeting all the surface water standards and that have good biological communities are considered to be supporting all their uses. For more information on the status of particular water bodies, please try the Biological Assessment Unit's website.
The following tables summarize aquatic life and human health numerical water quality standards per the 15A NCAC 2B .0200s. Complete implementation information for North Carolina is contained in the Environmental Management Commission's rules.
DOWNLOAD: NC Standards Table (PDF) [1 May 2007]
In some cases there may be no standard in the North Carolina standards tables. When that is the case, the first place to look for a standard is the EPA National Criteria. There are some pollutants that North Carolina does not usually see in effluent that EPA has promulgated criteria (standards) for and under 15A NCAC 2B .0208 can be used for protection of North Carolina's surface waters.
If there is no state or EPA criteria, then a search of EPA's ECOTOX database is conducted to determine if toxicity data is available. Under 15A NCAC 2B .0208, the lowest toxicity measure (LC50) is multiplied by a safety factor to obtain a protective concentration. A concentration derived in this way is called a chronic concentration and may be used to determine if water quality standards are being violated.