New national maps suggest flood risk is far higher than most people realize, in New York and across the country.
In some Adirondack counties, thousands more properties are considered at risk of flooding than federal flood estimates have shown, according to data by First Street Foundation, a Brooklyn-based nonprofit.
The group released a simple online tool, called Flood Factor, that lets people look up their flood risk by address. The website is part of a growing body of work by data scientists trying to reckon with the risk of disasters, like floods and fires, that occur at the boundary of development and nature.
The federal government has long tried to compute flood risk as well, but its data is harder to understand and takes longer to update.
Right now, the Federal Emergency Management Agency is working on flood risk maps along the Upper Hudson, Saranac and Ausable Rivers, but each river is a separate process and each process is expected to take several years.
That can be cumbersome. The Town of Peru, for instance, has said that existing flood maps are potentially inaccurate in some locations. But, according to FEMA, town officials will have to wade through two different mapping efforts to get the full picture of the risk because Peru straddles different watersheds that are being mapped separately.
The First Street Foundation work, by contrast, takes a bunch of data, including predictions about risk posed by increasingly common “rain bombs” and spits out calculations for virtually every building in the country.
While a report accompanying the data doesn’t mention the Adirondacks specifically, it points to unappreciated flood risks caused not only by aging federal risk models but by factors FEMA doesn’t take into account, like the rain bombs and streams that aren’t closely watched with flow monitors known as gages.
The Saranac River, for instance, has only one public stream gage. That gage, at the end of the river near Plattsburgh, wouldn’t give warning to people along the river about rising water levels – until it’s too late.
Photo: The Halloween storm of 2019 caused flooding in Hamilton County not seen since 2011. Mike Lynch/Adirondack Explorer
Editor’s note: This post first appeared in Ry’s weekly “Water Line” newsletter. Click here to subscribe.