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Related Practices
Related Practices

Massachusetts Finalizes Strict Perchlorate Drinking Water and Cleanup Standard

Beveridge & Diamond, P.C., July 28, 2006

As of July 28, 2006, the Massachusetts Department of Environmental Protection (MADEP) has published on its website final regulations setting drinking water and cleanup standards for perchlorate.  In particular, MADEP is setting the maximum contaminant level (MCL) in drinking water for perchlorate at 2 ppb, and the cleanup standard for groundwater that may be used for drinking water also at 2 ppb.  These standards were originally proposed by MADEP on March 14, 2006, and are being promulgated without change after public comment.  These standards are the lowest regulatory standards in the nation for perchlorate.

MADEP is proposing these standards because current scientific information suggests that there may be a link between human exposure to perchlorate and interference with the uptake of iodine by the thyroid gland, potentially interfering with proper development of the fetus and young children, as well as the metabolism of adults.  In the response to comments on the proposed rule, MADEP explained that a lower standard (e.g., 1 ppb) could discourage necessary disinfection of the public water supply.  In particular, trace perchlorate contamination in public drinking water supplies may be caused by disinfection using sodium hypochlorite.  MADEP concluded that the “MCL of 2.0 ppb provides the best overall protection of public health, considering the benefits of disinfection, while retaining a margin of safety for sensitive populations.”  MADEP also stated that it is developing guidance on best practices to be used in disinfecting the water supply.

The effective date of these regulations is not clear.  The final step in promulgating regulations in Massachusetts is publication in the Massachusetts Register.  MADEP expects these regulations to be published in the July 28, 2006 edition of the Massachusetts Register, and therefore has identified the effective date as July 28th.  However, this edition of the Massachusetts Register is not expected to be published until early August.

In Massachusetts, perchlorate was first identified in 2000 at the Massachusetts Military Reservation on Cape Cod, apparently resulting from military explosives.  In 2004, MADEP required public water suppliers to conduct extensive testing for perchlorate, which established that perchlorate had contaminated nine public drinking water supplies located across the state.  MADEP identified the likely source of the contamination as blasting in three cases, and as fireworks displays in three other cases.

Perchlorate contamination is not limited to Massachusetts.  Perchlorate contamination has been identified in at least 35 states, including all regions of the United States.  A May 2005 report by the Government Accountability Office identifies 395 sites nationwide that are contaminated with 4 parts per billion (ppb) or more perchlorate.  The United States Environmental Protection Agency estimates that the drinking water supplied to 11 million Americans contains some detectable perchlorate contamination.  For example, Lake Mead and the Colorado River, which supply drinking and irrigation water to parts of California, Nevada and Arizona, are contaminated with perchlorate.  Additionally, the California Department of Health Services reports that, as of August 2, 2005, 394 drinking water sources in California have detectable levels of perchlorate.