gross alpha particle activity. Both of these contaminants are known to cause serious human health effects, including certain cancers, when consumed for an extended period of time above the MCL. Gross alpha particle activity and arsenic are required to be tested for in certain counties (see Appendix C). PWTA data collected for gross alpha particle activity have shown that 9.6% of sampled wells exceeded the MCL of 15 pCi/L. It should be noted that sampling for gross alpha particle activity is only required in counties where NJDEP has historically found elevated levels. A total of 12% of those wells tested exceeded the New Jersey state arsenic standard of 5 µg/l. Arsenic test results continue to illustrate that certain areas of Northern New Jersey are more likely to experience arsenic contamination. Specifically, certain geological formations in the Piedmont region contain naturally occurring geologic units that may leach arsenic into the groundwater as it passes through this formation.
Test results for PWTA parameters that are required in all New Jersey counties continue to show that nitrate and fecal coliform/E. coli MCLs are most frequently exceeded, 2.7% and 2.2%, respectively. Both of these contaminants are regulated as acute parameters because exceeding the standard might lead to immediate health concerns. The percentage of volatile organic compounds (VOCs) exceedances above the MCL was 1.4%. This percentage is consistent with what was observed in the initial PWTA report. The percentage of wells exceeding the mercury MCL was 0.9%. Mercury testing is only required in the certain counties located in the southern part of the state
Secondary parameters (pH, manganese and iron) throughout New Jersey continue to exceed their particular Recommended Upper Levels (RULs) in a significant number of wells. Sixty-four (64) percent (or 32,530) of the 51,028 wells tested exceeded an RUL for at least one secondary drinking parameter, with pH exceeding the RUL in the greatest percentage of wells (45%). A total of 2,932 wells exceeded the RULs for all three parameters, 9,813 exceeded two; and 19,524 exceeded one of the RULs.
A comparison can be made between contaminants in Northern New Jersey and Southern New Jersey by looking at the counties that sampled for arsenic and gross alpha in the north and comparing it to the counties that sampled for mercury and gross alpha in the south. Figures 11 and 12 illustrate the comparison.