Indicator Report Data View Options
Why Is This Important?
Arsenic is a toxic chemical element that is naturally found in the Earth's crust, in soil, rocks, and minerals. It can also be released into the environment from agriculture and industrial activities. Arsenic can enter drinking water through the ground or as run-off into surface water sources. There is a wide variation in the levels of arsenic found in community drinking water systems' (CWS) supplies across New Mexico. In 2001 (effective January 23, 2006 for surface water- and 2007 or 2008 for ground water-supplied CWS), the Environmental Protection Agency (EPA) reduced the regulatory drinking water standard or Maximum Contaminant Level (MCL) from 50 micrograms per liter (mcg/L) to 10 mcg/L on the basis of bladder and lung cancer risks. People who drink water containing arsenic in excess of EPA's standard and over many years could experience skin, cardiovascular, neurological , liver, and kidney problems; they also may have an increased risk of diabetes and of developing certain cancers (such as bladder and lung cancers). Community systems' drinking water is routinely monitored and tested for arsenic by CWS to comply with the 10 mcg/L EPA standard for arsenic. (A CWS is a system that serves at least 15 locations or 25 people year-round, including most cities and towns, apartment buildings, and mobile parks with their own water supplies.) Every year, CWS send to their customers a consumer confidence report (also called a water quality report) that lists any levels of arsenic detected. EPA also requires all CWS to give their customers public notice when their water supply violates the arsenic standard. This would include information about what is being done to correct the situation. However, people who use their private wells water for drinking are solely responsible for testing the water for arsenic (for information about laboratories certified to test drinking water and certified home treatment units visit https://nmtracking.doh.nm.gov/environment/water/PrivateWells.html).
Arsenic concentrations (micrograms of arsenic per liter of water or mcg/L) in community drinking water systems (CWS) are used in conjunction with information about each CWS (such as service population) to generate the following measures shown in this report: 1) statewide arsenic concentration distribution in CWSs by mean and maximum over time, 2) annual distribution of mean and maximum arsenic concentration for persons served by CWS and 3) annual distribution of mean and maximum arsenic concentration by CWS. A CWS is a public water system (PWS) that serves year-round residents of a community, subdivision, or mobile home park that has at least 15 service connections or an average of at least 25 residents. These CWSs are a subset of all New Mexico PWSs. To measure arsenic concentration in CWS, drinking water samples are usually taken at entry points to the distribution system or representative sampling points after water treatment has occurred. Data Source: New Mexico Environment Department Drinking Water Bureau, Safe Drinking Water Information System (SDWIS). Measured arsenic concentrations in finished drinking water can be used to understand the distribution of potential arsenic exposure levels for populations served by community water supplies. Due to potential errors in estimating service population, the measures may overestimate or underestimate the number of potentially affected people. In addition, the older data (i.e., 1999 through 2004) may be of poor quality that could result in over- or underestimated arsenic concentration in CWS drinking water during 1999-2004. These measures allow for comparison of potential arsenic exposures between the populations served by different water systems over time.
How the Measure is Calculated
Numerator:Concentration of arsenic.