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Arsenic (cont.)

  • Counties that Sampled - The 10 counties in the Piedmont region of the State were required to sample for arsenic. The counties are Bergen, Essex, Hudson, Hunterdon, Mercer, Middlesex, Morris, Passaic, Somerset, and Union. These data are presented by county in Appendix G.

  • Health Effects - Arsenic is a known human carcinogen linked to increased risk of skin, lung, liver, kidney, and urinary bladder cancer.

  • Federal MCL - The MCL in effect for arsenic when the PWTA was signed was 50 µg/l, a standard that was set by the U.S. Public Health Service in 1942. On January 22, 2002 (effective February 22, 2002), the USEPA adopted a new MCL of 10 µg/l, however, those public water systems required to comply with the new arsenic standard had until January 23, 2006 to do so. For the purposes of the PWTA, the NJDEP used the newly adopted Federal MCL of 10 ug/l for assessing the PWTA results beginning in September 2002.

  • State MCL - The NJDEP proposed a new arsenic MCL of 5 µg/l which became effective January 23, 2006. For the purposes of this report, all the data were evaluated using the Federal MCL of 10 ug/l; those results that were analyzed by appropriate methods (except EPA method 200.7) were evaluated using the State MCL of both 5 ug/l.

  • Number of Wells over the federal MCL of 10 µg/l - A total of 605 wells (3.4%) of the 17,714 wells tested for arsenic had arsenic concentrations over the new federal standard of 10 µg/L.

  • Number of Wells over the state MCL of 5 µg/l – One of the analytical methods used to determine the concentration of arsenic in water, EPA Method 200.7, is not sensitive enough to measure arsenic concentrations below 8 µg/l. In order to determine the number and percent of wells that exceeded the NJDEP standard of 5 µg/l, it was necessary to first exclude samples analyzed using Method 200.7. A total of 12,263 samples (70% of arsenic results received) were analyzed for arsenic using the more sensitive analytical methods. Of those 1,445 wells (12%) exceeded the MCL of 5 µg/l.

  • Range of Concentrations - The arsenic concentrations in ground water ranged from 0 to 254 µg/l.

  • Geographic Distribution - Arsenic exceedances were most commonly found in Hunterdon (18%), Mercer (20%) and Somerset Counties (17%) (See Figure 5).

  • New Arsenic sampling requirements for Sussex and Warren Counties – PWTA data have shown that elevated arsenic concentrations also extend to the ground water supply in the Highlands Region of the State based on the results from some PWTA samples collected in those Northern counties that also extend into the Highlands Region. Therefore, beginning March 14, 2008, PWTA regulations were revised to require, all PWTA samples collected in Sussex and Warren be tested for arsenic in additional to all other required PWTA parameters.

The evaluation of the arsenic data using the more stringent State MCL (5 µg/l) resulted in three times the number of wells exceeding the arsenic standard when compared to the number of wells exceeding the federal MCL (10 µg/l).


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