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Important Information About Your Drinking Water

On October 29, 2012, the turbidity of the New York City Catskill-Delaware Water Supply at the Kensico Reservoir in Valhalla, New York in Westchester County exceeded 5 nephelometric turbidity units (NTUs) at approximately 6:30 PM. The turbidity returned to below 5 NTU at approximately 8:15 PM. The highest recorded turbidity value was 11 NTU.

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 the high winds that struck as Hurricane Sandy hit the region. The wind was sufficiently intense to cause large waves within Kensico Reservoir, churning up shoreline sediment in the vicinity of the point where water leaves the reservoir and enters the Delaware Aqueduct to the City. DEP acted quickly and placed the Delaware Aqueduct on by-pass, which avoids using water from the Kensico Reservoir and provides an alternative source of water to the Delaware Aqueduct. However, some turbid water did enter the Delaware Aqueduct before the by-pass operation could be completed. As a precaution, chlorine treatment was increased during this time to enhance the disinfection of the water. Additionally, before being sent into distribution, the water was also treated with UV light, which provides a secondary level of disinfection against potentially harmful microbiological contaminants such as Cryptosporidium and Giardia.

This incident constituted a treatment technique violation as specified in the Code of Federal Regulation (40 CFR §141.71(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.

Extensive monitoring in the distribution system—including at many testing locations in New York City—demonstrated that the water supply met all other drinking water quality standards. While there is no reason to believe 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. 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 can have various causes and 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) 595-5062. Questions about this notice can also be addressed by the New York City Department of Health and Mental Hygiene by calling 311.

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.

More Information

NYC Department of Environmental Protection
Public Affairs

59-17 Junction Boulevard
19th Floor
Flushing, NY 11373

(718) 595-6600