Is USGS responsible for monitoring drinking water?
No. The U.S. Geological Survey (USGS), and specifically, the National Water-Quality Assessment (NAWQA) Program, does not assess the quality of the Nation’s drinking water, such as for compliance. Rather, NAWQA assessments focus mainly on the quality of the available, untreated resource (source water), such as water upstream from treatment plants and water from public-supply and domestic wells. This is the first NAWQA study that also looks at the quality of water at public water-supply intakes and of treated (or “finished”) water, represented in this study by sampling of water after treatment but before distribution. The goal of such efforts is to understand and compare occurrence patterns in source water to patterns that may also occur in treated water. The assessments are intended to complement drinking-water monitoring required by Federal, State, and local programs, which focus primarily on post-treatment compliance monitoring. In addition, findings are intended to evaluate what is in the source water to help guide those involved in decisions on treatment processes in the future.
Does USGS regulate drinking water?
No. The U.S. Geological Survey (USGS) is a non-regulatory agency under the U.S. Department of Interior and is the primary Federal agency responsible for providing scientific information on the quality of the Nation’s water resources. USGS information is intended to facilitate effective management of water resources and ensure long-term availability of water that is safe for drinking and recreation and is suitable for industry, irrigation, and fish and wildlife.
What does “regulated” refer to?
Under the authority of the Safe Drinking Water Act, the USEPA establishes drinking-water standards, such as Maximum Contaminant Levels (MCLs), to limit the level of contaminants in the Nation’s drinking water. After reviewing studies of health effects, the USEPA sets a Maximum Contaminant Level Goal (MCLG), the maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health of persons would occur, and which allows an adequate margin of safety. MCLGs are non-enforceable public health goals. Because MCLGs consider only public health and not the limits of detection and treatment technology, sometimes they are set at a level that water systems cannot meet. When determining an MCLG, the USEPA considers the risk to sensitive subpopulations (infants, children, the elderly, and those with compromised immune systems) of experiencing a variety of adverse health effects.
Once the MCLG is determined, the USEPA sets an enforceable standard. In most cases, the standard is a Maximum Contaminant Level (MCL), the maximum permissible level of a contaminant in water that is delivered to any user of a public water system.
The MCL is set as close to the MCLG as feasible, which the Safe Drinking Water Act defines as the level that may be achieved with the use of the best available technology, treatment techniques, and other means that the USEPA finds are available (after examination for efficiency under field conditions and not solely under laboratory conditions), taking cost into consideration.
Additionally, the Federal government generally delegates to States the responsibility for enforcing primary standards. Therefore, States also may have enforceable drinking-water regulations that are more stringent than Federal standards. These standards may vary among States; specific information can be obtained from State drinking-water programs. More information on this topic is included at http://www.epa.gov/safewater/links.html.