April 18, 2006

Contact: DEP (718) 595-6600
DOH (212) 676-1520

Important Information About Your Drinking Water

On March 23rd, 2006, the turbidity of the New York City Catskill Water Supply at the Kensico Reservoir in Valhalla, New York in Westchester County exceeded 5 nephelometric turbidity units (NTUs) at approximately 7:40 p.m. and stayed above 5 NTU for about 20 minutes.  The highest recorded turbidity value was 19 NTU.

This incident constituted a treatment technique violation as specified in the Code of Federal Regulation 40 CFR §140.71(c)(2)(i) and the New York State Sanitary Code 10 NYCRR section 5-1.30 (c ) and (d). Although this was not an emergency, and no action is required on your part, you, as our customer have a right to know the circumstances. There is no reason to stop using the water supplied to your home/business as a result of this violation.

Turbidity is a measure of water clarity related to the amount of suspended matter present in the water.  The elevated turbidity was a direct result of a routine gate operation related to an aqueduct start up at the Catskill Lower Effluent Chamber that was performed during the evening of March 23rd.  The aqueduct had been shut down earlier in the day to perform repair work and the start up later that evening caused sediment that had settled to become re-suspended and to enter the Catskill Aqueduct to the City.  DEP acted quickly and reduced the flow to allow the solids to settle thus reducing the turbidity.  However, some turbid water did enter the Catskill Aqueduct before the flow reduction was completed.  As a precaution, chlorine treatment was increased during the operational changes to enhance the disinfection of the water.

Extensive distribution system monitoring demonstrated that the water supply met all other drinking water quality standards.  While there is no evidence that this turbidity incident introduced any microbiological contaminants into the drinking water, people with severely compromised immune systems, infants and some elderly may have been at increased risk for a very brief period following this event.  State and federal drinking water rules require public notification that includes the following language:  Turbidity has no health effects.  However, turbidity can interfere with disinfection and provide a medium for microbial growth.  Turbidity may indicate the presence of disease causing organisms.  These organisms include bacteria, viruses, and parasites which can cause symptoms such as nausea, cramps, diarrhea, and associated headaches. These symptoms are not caused only by organisms in drinking water. If you experience any of these symptoms and they persist, you may want to seek medical advice from a health care provider.

For further information please call the New York City Department of Environmental Protection, Bureau of Public Affairs at (718) 595-6600 or the New York City Department of Health and Mental Hygiene, Office of Public Health Engineering at (212) 676-1520. 

Please share this information with other people who drink this water, especially those who may not have received this notice directly.  You can do this by posting this notice in a public place or distributing copies by hand or mail.  Landlords and building managers responsible for multi-family dwellings – please post this notice in a conspicuous place.

Public Water System ID#: NY7003493