Responding to the US Environmental Protection Agency’s announcement yesterday that it plans to significantly lower the standard for arsenic allowed in drinking water, MWRA today announced that testing results for arsenic performed since January, 1999 at four locations in the MWRA system were all far below EPA’s newly proposed standard.

Under the federal Safe Drinking Water Act, the EPA proposes to lower the existing arsenic standard of 50 parts per billion to 5 parts per billion beginning in 2001. EPA will also take public comment on alternative standard levels of 3, 10, and 20 parts per billion. There has been controversy across the country on possible health risks and compliance costs associated with the different standard levels, especially in communities not as fortunate as greater Boston in naturally low occurrence levels of arsenic.

In 65 tests for arsenic taken since January 1999, MWRA laboratories found no detectable quantities in 57 of the samples. Of the 8 samples analyzed with detectable quantities, the average was 1.2 parts per billion, well below the possible standard levels.

Arsenic is a naturally occurring mineral that comes from erosion of rocks and soil. In the U.S., highest arsenic levels are found in the Southwest and parts of the Midwest, West, and New England. Communities served by ground water supplies, rather than reservoirs and streams, are more likely to find higher arsenic levels. MWRA drinking water comes from the Quabbin and Wachusett Reservoirs in Central Massachusetts, very large reservoirs with high water quality that do not have high levels of arsenic.

The American Water Works Association, which represents many water utilities across the country, has proposed that EPA adopt a new lower standard of 10 parts per billion. This standard would be equal to the World Health Organization and would bring reductions in a large majority of cities where arsenic is a problem.

MWRA routinely tests for 122 contaminants. Arsenic is testing at four locations each month. Overall testing results for 1999 will be published in MWRA’s annual Report To Consumers on Your Drinking Water distributed this June to every household in MWRA’s water service area.