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 District
BDG1
N-9561
Magothy
682 ft.
9/26/01
3
Garden City Village
13
N-7058
Magothy
440 ft.
9/25/01
3
Glen Cove City
Kelly
N-9334
Magothy
298 ft.
8/6/01
3
Hicksville Water District
6-2
N-3878
Magothy
428 ft.
10/15/01
5
Hicksville Water District
9-1
N-8778
Magothy
590 ft.
10/31/01
2
Jericho Water District
13
N-6093
Magothy
606 ft.
10/15/01
2
Roslyn Water District
8
N-8010
Magothy
448 ft.
8/14/01
2
Town of Hempstead W.S.
B.G.#1
N-8956
Magothy
530 ft.
1/9/02
6
Town of Hempstead W.S.
B.G.#2
N-8957
Magothy
584 ft.
1/9/02
2
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.