Perchlorate and Nitrate

  1. translate_icon

As part of the Pesticide Monitoring Program, groundwater samples were also collected for inorganic chemical analyses. Of particular interest were the Nitrate and Perchlorate concentrations.

Perchlorate

Nine of the 60 (15%) public supply wells sampled in Nassau County exhibited perchlorate detections. The detections ranged from 2 ug/L to 6 ug/L, well below the New York State Department of Health (NYSDOH) Action Level for this compound of 18 ug/L. All detections occurred in the Magothy aquifer, with depths ranging from 298 to 682 feet. Perchlorate was found in the public supply wells from 7 different water systems and 2 water systems, Hicksville Water District and The Town of Hempstead W.S. had detections in two of their wells. Table 2 summarizes the perchlorate detections in Nassau County's public supply wells.

Table 2 - Summary of Perchlorate Detections in Nassau County Public Supply Wells

WATER SYSTEM
LOCAL WELL NO.
NYSDEC WELL NO.
AQUIFER
WELL DEPTH
SAMPLE DEPTH
PERCHLORATE (UG/l)
Bethpage Water DistrictBDG1N-9561Magothy682 ft.9/26/013
Garden City Village13N-7058Magothy440 ft.9/25/013
Glen Cove CityKellyN-9334Magothy298 ft.8/6/013
Hicksville Water District6-2N-3878Magothy428 ft.10/15/015
Hicksville Water District9-1N-8778Magothy590 ft.10/31/012
Jericho Water District13N-6093Magothy606 ft.10/15/012
Roslyn Water District8N-8010Magothy448 ft.8/14/012
Town of Hempstead W.S.B.G.#1N-8956Magothy530 ft.1/9/026
Town of Hempstead W.S.B.G.#2N-8957Magothy584 ft.1/9/022


Nitrate

The average nitrate concentration found in the 61 public supply wells sampled in 2001 was 2.5 mg/L and no wells exceeded the nitrate MCL of 10.0 mg/L. Well N-3523, "Munsey Park # 8", from the Manhasset-Lakeville Water District had the highest nitrate concentration of 9.8 mg/L. The range of nitrate detections is summarized below.

NO3 Detection Range
>10 mg/L
5-10 mg/L
0-5 mg/L
ND
# PSW Detected0152821