January 09, 2014

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Adam Bosch (845) 334-7868
Ted Timbers (718) 595-6600

Department of Environmental Protection to Release Water from Ashokan Reservoir to Reduce Potential for Flooding in Months Ahead

Release of High-Quality Water will Achieve 90-Percent Storage Objective in State Protocol

The New York City Department of Environmental Protection (DEP) on Thursday announced that it had begun to release high-quality water from Ashokan Reservoir to achieve the 90-percent storage objective required by state regulators, and to further reduce the potential for flooding during the late winter and spring.  DEP began increasing the release rate as of 9 a.m. Thursday and plans to reach a release rate of 150 million gallons per day (mgd) by Thursday evening, and 300 mgd by Friday evening.  After consulting with Ulster County officials, it was determined that the release rate should be increased slowly in order to reduce the risk of ice dams forming along the lower Esopus Creek. 

The releases are being made under a provision of the state-issued Interim Release Protocol that calls for DEP to release water when Ashokan Reservoir is projected to be more than 90 percent full between mid-October and mid-March.  As of Thursday morning, Ashokan Reservoir storage was 89 percent.  The protocol also requires DEP to account for a seven-day runoff projection from the National Weather Service, which in this case will cause reservoir storage to exceed 90 percent because of snowmelt from higher temperatures and rainfall predicted for the weekend.

“Downstream communities have long asked for releases that will remove water ahead of storms, snow melt and spring rains to further reduce the probability that Ashokan Reservoir will spill in the months ahead,” DEP Commissioner Carter Strickland said. “To fulfill the City’s commitment to transparency about our operations, DEP has reached out to downstream elected officials and other stakeholders to inform them about the releases.”

DEP expects to release high-quality water through the release channel and into the lower Esopus Creek.  For more than a year, the turbidity of daily releases made from Ashokan Reservoir has been very low.  Water during the current period of release is expected to remain around 4.1 nephelometric turbidity units (NTU).  For perspective, the turbidity standard for drinking water is 5 NTU or less. Over the past week, naturally occurring turbidity in the lower Esopus Creek, as measured by U.S. Geological Survey gauges at Lomontville and Mount Marion, has ranged from 2 to 140 NTU due to storm runoff.  During that same time period, the creek’s flow at those gauges has ranged from 55 to 1,450 mgd.

The number of days that water will be released from Ashokan Reservoir is yet to be determined, and will depend on runoff from a moderate rain event that is predicted for the weekend.

Ashokan Reservoir storage, both actual and forecasted, has increased in recent weeks because of significant snowfall, rain, and runoff.  According to DEP and National Weather Service data, there is roughly 1.5 billion gallons of water in the snowpack throughout the watershed that feeds Ashokan Reservoir, which holds as much as 128 billion gallons.  DEP has used advanced modeling tools to account for the weather forecast, expected runoff, current reservoir storage, and myriad other metrics before starting to release water.

As part of its commitment to readily provide information about water releases, DEP last year began posting on its website the daily release rate and turbidity of releases from Ashokan Reservoir.  That information, which is updated every morning, can be found by clicking this link.  Flow and turbidity information from the Lomontville and Mount Marion stream gauges, which are located downstream of Ashokan Reservoir, can also be found on that page. 

DEP manages New York City’s water supply, providing more than one billion gallons of water each day to more than 9 million residents, including 8.4 million in New York City, and residents of Ulster, Orange, Putnam, and Westchester counties.  This water comes from the Catskill, Delaware, and Croton watersheds that extend more than 125 miles from the City, and the system comprises 19 reservoirs, three controlled lakes, and numerous tunnels and aqueducts. DEP has nearly 6,000 employees, including almost 1,000 scientists, engineers, surveyors, watershed maintainers and others professionals in the upstate watershed.   In addition to its $68 million payroll and $157 million in annual taxes paid in upstate counties, DEP has invested more than $1.5 billion in watershed protection programs—including partnership organizations such as the Catskill Watershed Corporation and the Watershed Agricultural Council—that support sustainable farming practices, environmentally sensitive economic development, and local economic opportunity.  In addition, DEP has a robust capital program with over $14 billion in investments planned over the next 10 years that will create up to 3,000 construction-related jobs per year. For more information, visit nyc.gov/dep, like us on Facebook at facebook.com/nycwater, or follow us on Twitter at twitter.com/nycwater.