Seattle planners predict bigger flood zones due to climate change

Jan 14, 2013

It’s data that’s been collected and analyzed for several years now.

But predictions on how high tides and extreme storm events might combine to cause flooding in Seattle are seeming less and less like science fiction.

The City has unveiled a new map, showing huge areas that are much more likely to end up waterlogged during storms. And it says the estimates are no longer considered extreme. 

Members of Seattle’s Green Ribbon Commission on Climate Change gathered on the shores of Eliot Bay, at the north end of Myrtle Edwards Park. They braved brisk morning temperatures at this particular spot for symbolic reasons. It’s the place where the highest tide of the year came in – the so-called King tide.

“By 2050, this King Tide will not be out of the ordinary. It will be the norm,” said  Councilmember Jean Godden, chair of the committee that oversees Seattle Public Utilities.

The tides are higher than ever now, because climate change is causing sea levels to rise.

“And this is not the first time that Seattle has talked about climate change, but this map, this map that shows where we will be in 2050, brings new information to the conversation,” Godden said.

The map shows in color codes that areas painted in two shades of blue can expect frequent flooding, if storm surges combine with the highest tides. The flood zones are all over the city: from Interbay and Ballard in the North, to South Park and West Seattle, where about a hundred properties were already flooded at high tide last month.

Councilmember Mike O’Brien, who chairs Seattle’s Energy and Environment Committee, says that’s just the beginning of a new reality, with big risks to the city’s port, unless planning takes climate change into account.

“When you look at the map and see that most of Harbor Island can be under water during these events, it really causes us concern about what the future looks like and how we adapt to that,” O'Brien said.

Moving forward, the councilmembers have announced that all projects undertaken by Seattle Public Utilities must take climate change impacts into consideration, and put them on par with safety and reliability.

That means taking a new look at how we invest in our hydropower systems, for example, or in the infrastructure that separates our sewage from cleaned water, or what the design of Seattle’s new voter-approved seawall will look like.

There’s also a new list of recommendations from the Green Ribbon Commission. Some are short term actions people can take; others will require longer-term commitments and cultural changes, if the city is to reach its goal of carbon neutrality, just 37 years from now.