DEP Environmental Protection Invoices, 1999-2001

NYC 9/11 Public Portal Document

Catskill Water Supply.

Over the last several days, turbidity levels from the Ashokan Reservoir have been steadily increasing as a result of an intense rainstorm of December 16-17, 2000. This storm (and subsequent precipitation) has resulted in a surge in the Ashokan Reservoir storage levels and high turbidity readings, particularly within the West Basin of the Reservoir. These high water levels have also made it difficult for DEP to isolate for a prolonged period of time the more highly turbid waters of the West Basin of Ashokan Reservoir, from the less turbid waters of the East Basin, where we are currently drawing water from. Since the storm event, the turbidity levels leaving Ashokan Reservoir into the Catskill Aqueduct (EARCM) have exceeded 20 NTU. DEP water quality monitoring efforts indicate that there is the possibility that Ashokan Reservoir conditions may worsen causing even higher turbidity loading to Kensico Reservoir. In addition, the same storm event has affected Rondout Reservoir and the Delaware Water Supply. Turbidity — :- entering Kensico from the Delaware Supply is currently 2 NTU. The elevated turbidity on both w the Catskill and the Delaware Water Supply, coupled with the fact that the Croton System is - currently shut down and cannot be used as an alternate supply, means that the turbidity in Kensico will worsen significantly over the next several days. DEP finds that these circumstances require the treatment of the Catskill Water Supply with alum to coagulate and settle the particular/colloidal matter entering the Kensico Reservoir. DEP would add alum at the alum plant in Pleasantville, just above the Upper Effluent Chamber of the Kensico Reservoir.

At the present time, turbidity levels of the source water leaving the Kensico Reservoir are above 1.5 NTU. During the time that alum treatment is underway, DEP will comply with the enclosed monitoring and sampling schedule (weather permitting) to insure the integrity of the water supply.

As stated above, DEP submits this application for an emergency SPDES permit to DEC pursuant to 6 NYCRR Part 621.12(b)(1-3). In accordance with these provisions, accompanying this application, which has set forth the reasons for the emergency permit, DEP submits to you the following: the enclosed monitoring and sampling protocols and a location map of the proposed project.

As detailed above, DEP concludes that the recent storm surge and the resulting high turbidity levels constitute an emergency and requires DEC's immediate attention.

Thank you for your attention to this matter. If you have any questions please contact the undersigned at (718) 595-6555 or Dr. David Lipsky, Deputy Chieff Watershed Operations, Division of Drinking Water Quality Control at (914) 773-4436.

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NYC-WTC 000137774