NOAA: Coastal population boom increases hazard risks

Mar 25, 2013

A population boom along the U.S. coastline threatens to put residents at increased risk in case of an extreme storm that heavily damages infrastructure, according to a new report by the National Oceanic and Atmospheric Administration.

Latest census data states 123 million Americans, or 39 percent, live along the coast. And growth trends indicate that number will balloon to nearly 134 million people — a growth of 8 percent — by 2020.

“As more people move to the coast, county managers will see a dual challenge — protecting a growing population from coastal hazards, as well as protecting coastal ecosystems from a growing population,” said Holly Bamford, Ph.D., assistant NOAA administrator for the National Ocean Service.

The coastal shoreline counties have seen a huge population spike in recent decades. The 452 counties, which make up less than 10 percent of mainland U.S., saw a growth of 39 percent between 1970 and 2010.

The country’s general population grew at a higher rate of 52 percent during the same period; however, growth along the coast resulted in significantly heavier density — 125 people added per square mile versus the 36 people added per square mile in the rest of the U.S.

“Population density in shoreline counties is more than six times greater than the corresponding inland counties," said Kristen Crossett of NOAA’s National Ocean Service. "And the projected growth in coastal areas will increase population density at a faster rate than the country as a whole.”

Several counties in Western Washington saw growth that exceeded the national average during the same period. San Juan County saw the biggest growth of 308 percent followed by Jefferson County, where the population ballooned by 180 percent. Whatcom County’s population increased by 145 percent, Skagit County’s by 123 percent, and Clallam County’s by 105 percent.

The coastal population is even bigger when non-shoreline watershed counties — those that drain to coastal watersheds — are also considered. Together, the two groups make up more than half — or 52 percent — of the general population and take up less than 20 percent of U.S. land. Density in these counties is more than five times greater than their inland counterparts, according to NOAA.

Credit NOAA