Water Reuse

Wastewater Regulations

The Clean Water Act (CWA) of 1972 established the foundation for wastewater discharge control in the United States.  The CWA's primary objective is to restore and maintain the chemical, physical and biological integrity of the nation's waters.

The CWA established a control program for ensuring that communities have clean water by regulating the release of contaminants into waterways.  Permits that limit the amount of pollutants discharged are required of all municipal and industrial wastewater dischargers under the National Pollutant Discharge Elimination System (NPDES) permit program.

Water quality standards are the foundation of the water-quality based control program mandated by the CWA.  A water quality standard consists of four basic elements:

  1. designated uses of the waterbody (e.g. recreation, water supply, aquatic life, and/or agriculture);
  2. water quality criteria to protect designated uses (numeric pollutant concentrations and narrative requirements);
  3. an antidegradation policy to maintain and protect existing uses and high quality waters; and
  4. general policies addressing implementation issues (e.g. low flows, variances, and mixing zones).

By adopting water quality standards, states are able to determine which healthy waters need protection, which waters must be restored and how much pollutant reductions are needed.  Consequently, these water quality standards set a goal for restoring and protecting a watershed over the long term.

Water quality montiroing provides the data to characterize waters and identify changes or trends in water quality over time.  The collection of monitroing data enables states to identify existing or emerging water quality problems and determine whether current pollution control mechanisms are effective in complying with the regulations.  The CWA requires that each state monitor and assess the health of all their waters and report their findings every two years to the EPA.

The Total Maximum Daily Load (TMDL) calculates the maximum amount of a pollutant allowed to enter a waterbody, also known as the loading capacity, so that the waterbody will meet and continue to meet water quality standards for that particular pollutant.  The TMDL allocates that load to point sources (identified sources of pollution such as municipal and industrial wastewater dischargers) and nonpoint sources (unidentified sources of pollution such as agricultural runoff).

Sources:
http://www.epa.gov/OWM/primer.pdf
http://www.epa.gov/owow/tmdl/overviewoftmdl.html