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September 3, 2011


Michael Saucier  (718) 595-6600

DEP Submits Post-Storm Report on Gilboa Dam to State DEC

Incident Report Confirms Dam Is Safe

Environmental Protection Commissioner Carter Strickland today announced that DEP has submitted a post-storm incident report on Gilboa Dam to the New York State Department of Environmental Conservation, based upon inspections and engineering analysis by outside and in-house dam safety experts.  The report concludes that the Gilboa Dam, which was structurally safe beforehand and undergoing a scheduled $350 million upgrade, weathered the heavy rain associated with Hurricane Irene and remains safe and structurally sound.  DEP’s report to the State DEC is attached to this press release and will be posted on DEP’s website.
The report states that the dam at no point had leakages; that it incurred no significant erosion or damages; and that it was structurally sound before, during and after the storm. The dam did incur some minor damage to non-structural components of the kind that would be expected with a storm of the intensity of Hurricane Irene — such as the damage to one of the steps of the side channel of the spillway. DEP will continue to assess the Gilboa Dam’s condition and to take necessary response actions.
Ahead of the storm, DEP released 2.8 billion gallons of water through siphons and diverted 2.4 billion gallons from the reservoir to the Ashokan Reservoir. Leading into the storm, the National Weather Service predicted that rainfall would cause Schoharie Reservoir to crest at elevation 1131.4 feet. Based on that prediction, DEP began enhanced monitoring at the dam. On Sunday, August 28, the drainage area to Schoharie Reservoir received unpredicted rainfall of over 14 inches in some locations in the watershed, and these extraordinary flows raised the water level to an unprecedented peak of 1,137.95 feet between 2:35 p.m. and 2:55 p.m. — nearly one and a half feet higher than the previous record set during a storm in January 1996. Storm-related impacts on the reservoir and the dam triggered DEP’s Emergency Action plan that has been in place since 2005. DEP did not believe at any point that the dam was in danger of imminent failure but higher-than-predicted amounts of rain coupled with the loss of electronic monitoring devices due to the storm increased the potential risk to communities below the dam. To protect the public, the plan requires an area-wide evacuation until extraordinary conditions — like last weekend’s storm — have abated, and until any potential impacts to the dam are assessed. DEP’s experts began assessing the dam on Sunday, August 28, and completed a preliminary assessment on August 29, when it de-activated the emergency action plan.  DEP’s experts continued assessments throughout the week.

Post-Storm Incident Report

More Information

NYC Department of Environmental Protection
Public Affairs

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