Monitoring Results From Public Supply Wells

Eight of the 66 public supply wells tested (12%) exhibited pesticide detections in 2001 and 6 different pesticides were detected in Nassau County public supply wells. TCPA (tetrachloroterephthalic acid), a dacthal metabolite, was the most frequently detected pesticide compound in Nassau County public supply wells, being detected in six of the 66 (9%) public supply wells tested in Nassau County. The detections ranged from 7 ug/L to 17 ug/L. The Maximum Contaminant Level (MCL) for this compound is the generic Unspecified Organic Contaminant (UOC) standard of 50 ug/L.

The 5 other pesticides that were detected in Nassau County public supply wells were: Atrazine, Dibromochloropropane (DBCP), Desethylatrazine, Ethylene dibromide (EDB) and Prometon. Table 1 lists the public supply well, water system and level detected for each detected pesticide in Nassau County.

Table 1 - Summary of Pesticides Detected in 
Nassau County Public Supply Wells - 2001
PESTICIDE WELLS(S)
DETECTED		 LOCATION LEVEL
(ug/L)		 MCL
(UG/L)
Atrazine N-3704 WestHempstead W.D. 0.19 3.0
Desethyhtrazine N-9211 City of Glen Cove 0.05 50.0
DBCP
(Dibromachbropropane)		 N-9211 City of Glen Cove 0,11 0.12
EDB
(Ethylenedibromide)		 N-8010 Roslyn Water District 0.07* 0.05
Prometon N-4077 W.A. of Western Nassau 0.12 50.0
TCPA N-10612
N-9211
N-37
N-12639
N-3704
N-10401		 Garden City Park W.D.
City of Glen Cove
Sands Point Village
Sands Point Village
West Hempstead W.D.
West Hempstead W.D.		 7
17
7
10
6
7		 50.0
* Exceeds MCL of 0.05 ug/L established for this compound

Only one of the pesticides detected, Ethylene dibromide (EDB), exceeded the Maximum Contaminant Level (MCL) established for the compound. EDB was detected at a level of 0.07 ug/L in Roslyn Water District's Well # 8 (N-8010), exceeding the 0.05 ug/L MCL established for this compound. This well has a history of EDB detections from water system and NCDH routine monitoring and, since 1998, utilizes granular activated carbon (GAC) filtration.