Water Quality Definitions

Best Management Practices (BMP): Practices are designed to conserve soil and water resources used in farming and to lessen environmental damage from pollution sources, like runoff or erosion management systems at a construction site or timber stand, animal waste storage systems at a farm, or buffer strips along riparian zones.

Clean Water Act (CWA): The CWA establishes a regulatory framework to protect water quality throughout the United States. The goal is to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters (U.S.C. 1251-1387).”

Impaired Water Body: An impaired water body is one that is polluted. A state’s TMDL “Impaired Waters List” is a list of the state’s waters that fail or are threatened to fail the state’s water quality standards, even after the installation of pollutant controls. These lists are also referred to as “TMDL Lists.”

National Pollution Discharge Elimination System (NPDES) Permit: A NPDES permit is a pollution discharge permit issued, pursuant to the Clean Water Act, by a state agency or by the U.S. EPA to a “point source” discharger. The permit specifies how much of a given pollutant can be present in a discharge and establishes monitoring and reporting requirements for that point source.

Nonpoint source pollution (NPS):
Pollution that is diffuse, entering a waterway from a wide geographic area rather than a single pipe. Examples include polluted runoff from urban streets, agricultural fields, timber harvesting areas, airborne pollution, and contaminated sediment.

Point source pollution (PS): Pollution caused by a discharge of waste via a pipe. Examples include discharge from municipal wastewater treatment facilities and industries. Most sources are required to have permits with conditions designed to control discharges.

Total Maximum Daily Load (TMDL):
A watershed cleanup program, required by the Clean Water Act under Section 303(d), designed to deal with problem pollutants from all sources, including point and nonpoint sources. This program is important for nonpoint source controls in particular because of the absence of other mandatory control mechanisms under federal law. Under this provision, states are required to identify waters that are polluted even after all mandated controls have been applied. States must then develop watershed cleanup plans called “TMDLs.” In order for the U.S. EPA to approve a proposed TMDL, the state must demonstrate that there is a “reasonable assurance” that the controls-on nonpoint and point sources alike-can be achieved.

TMDL Coordinator: Each TMDL water quality study requires significant coordination and planning with local stakeholders. TMDL coordinators manage the development of TMDLs within their assigned basin, working with the watershed coordinators, local agencies, and landowners. The TMDL coordinators are part of the TMDL / Watershed Section of the Utah Division of Water Quality.

Total Phosphorous (TP): Total phosphorus is all of the phosphorus found in a water sample. Phosphorus exists in water in either a particulate phase or a dissolved phase. Phosphorus in natural waters is usually found in the form of phosphates (PO4-3). Phosphates can be in inorganic form or organic form. The U.S. EPA recommendations total phosphate should not exceed 0.05 mg/L (as phosphorus) in a stream at a point where it enters a lake or reservoir.

Total Suspended Solids (TSS):
Total Suspended Solids (TSS) are solids suspended or dissolved in water that can be trapped by a filter. TSS can include a wide variety of material, such as silt, decaying plant and animal matter, industrial wastes, and sewage. High concentrations of suspended solids can cause many problems for stream health and aquatic life.

Watershed: The geographic region from which water drains into a particular water body, like a bay, river, or lake. The watershed includes the land resources as well as the water body. Also called a drainage basin.

Watershed Coordinator: A watershed coordinator serves as the critical link between agencies and local stakeholders. These positions are locally sponsored and are tasked to promote stewardship of water quality and implement practices that will protect and restore our streams and lake's beneficial uses.