International Knowledge-Sharing for Stormwater Resiliency


The New York City Department of Environmental Protection (DEP) serves over 9 million New Yorkers, provides clean drinking water to City residents and several New York State counties, and stormwater management and wastewater treatment for the City. With the massive amount of people depending on these critical services, we have been proactively studying climate change and its potential impacts on water for over a decade.

When Hurricane Sandy struck New York City in October 2012, causing over $19 billion in damages, the storm highlighted our vulnerabilities to extreme weather and the importance of planning for future events. Efforts that were already underway, including implementation of the 2010 Green Infrastructure Plan, will enhance our resiliency to increasing rain. Similarly, implementation of more recent plans—such as the 2013 Wastewater Resiliency Plan released after Hurricane Sandy—will protect critical facilities from sea level rise and storm surge. In addition, New York City recently received a Municipal Separate Storm Sewer System (MS4) permit, effective August 1, 2015, which aims to reduce the amount of pollutants carried off by stormwater during a storm event to local waterbodies. DEP has collaborated with other involved agencies and our very first Stormwater Management Plan (SWMP) is currently in development, and will be submitted to the New York State Department of Environmental Conservation by August 1, 2018. This plan is yet another comprehensive and integrated approach, involving public participation and where appropriate, interagency coordination to identify measurable goals for each of the best management practices and reduce the discharge of pollutants of concern and specified pollutants to the maximum extent practicable.

In planning for stormwater and climate change challenges, we recognize that other cities around the world face similar challenges and, in response, are developing new and innovative approaches. For example, the City of Copenhagen, Denmark, has experienced intense rainfall events (also known as “cloudbursts”) that resulted in extreme localized flooding. In response, the City developed a Cloudburst Management Plan, to manage more rainwater and become both a more resilient and livable city.

Recognizing the opportunity to learn from each other, DEP and the City of Copenhagen’s Technical and Environmental Administration recently initiated an innovative knowledge-sharing agreement with the goals of addressing cloudbursts, sea level rise, and associated physical and societal impacts. The agreement highlights that both cities will share best practices on various strategies of rainfall retention as well as models for estimating economic savings of robust stormwater management systems. Over the next three years, DEP and Copenhagen will communicate experiences and information regarding the development of climate-resilient neighborhoods through stormwater solutions, and promote and share advancements with our peers.


Shree Dorestant, Stormwater Management Program Coordinator, and Alan Cohn, Climate Program Director, work in DEP’s Bureau of Environmental Planning and Analysis.  Shree assists with the MS4/stormwater program development, management and implementation; preparation of permit deliverables; inter-Departmental coordination and support for other stormwater related analyses and planning efforts. She received her Bachelor of Science Degree in Biology and Master of Public Administration (Water Resources Management & Policy) Degree from Albany State University in Albany, GA; and a Doctorate of Management (Environmental and Social Sustainability) Degree from Colorado Technical University in Colorado Springs, CO.

Alan Cohn leads and coordinates studies of climate change impacts and adaptation for New York City’s water supply, stormwater management, and wastewater treatment systems, and works closely with leading climate resiliency experts in the US and internationally. He received a Bachelor of Science in Atmospheric Science from Cornell University and a Master of Science in Atmospheric and Oceanic Science from the University of Maryland.

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