Friends of the Waterfront
Olympia, Washington

Rising Sea Levels and the Isthmus

Almost everyone now agrees that the planet is getting warmer, polar ice is melting, and sea levels will keep rising. According to The Olympian's coverage of a recent city report (Part 1, Part 2), downtown areas already come very close to flooding during some winter high tides, and Olympia may well have a 3-foot rise in sea levels during the next 100 years, or more. The bright blue on this city map shows estimated flooding with 2 feet more water at high winter tides. (Click on it for the full size version.) The whole isthmus floods.

Granting this rezone request will put major new development on the lowest area in the city, where it will be most threatened by flooding and water rising through the soil. Taxpayers will have to pay to defend million dollar condos with dikes, seawalls, and pumping systems. Building and maintaining these will cost tens or even hundreds of millions of dollars. The city has barely begun to think about this issue; it should have at least some sense of what protecting these buildings might cost and how we might pay for it before it cheerfully commits itself to this risk.

Olympia's problems

  1. The city's best current projections estimate a rise in global open ocean levels of between 7 and 23 inches over the next century.
  2. But as the tide moves in from the ocean to the shallower areas of the Sound, the water piles up like water sloshing up in the end of a bathtub. A one foot rise in the tide levels at the entrance to Puget Sound is projected to produce two feet of tide level rise in Seattle, and three feet here. (Graph)
  3. Furthermore, some studies indicate downtown Olympia is settling about a foot a century - the city currently projects 8 inches by 2100.
  4. So, one foot of rise in global ocean levels could well produce 3 to 4 foot higher tide levels at Olympia - the city has already done estimates of the effects with 4 and 5 foot higher tides.