Waterfront property owners face options in response to sea-level rise

Rising sea levels and isolated floods will be an increasing challenge for waterfront property owners, according to experts I interviewed for a story published this week in the Encyclopedia of Puget Sound.

The Vechey home and bulkhead before the big move. // Photo: John Vechey

Changing conditions call for property owners to consider their options with regard to their shoreline — not just for today but for the long run. What I learned while researching this story is that every waterfront site will respond differently as the highest tides go higher and higher.

Before I started my inquiry, I thought the obvious answer would be for people to build taller and stronger bulkheads — despite well-known environmental damage. And that may be the only answer for some. But for others, that approach could be a waste of money, as bigger walls degrade the owners’ enjoyment of the beach as well disrupting natural systems. Alternatives include moving or raising a house or even replacing a bulkhead with “soft shore” protections.

After the home was moved back from shore and the bulkhead removed. // Photo: John Vechey

Sea levels in Puget Sound are rising slowly at this time, with the actual rate dependent on location. We live in a tectonically active area, with major movements along continental plates. As a result, the ground is sinking in most areas around Puget Sound, adding to the relative rise in sea level.

In Seattle, the sea level has risen about 9 inches since 1900 and is expected to rise an additional 4 to 56 inches (4.75 feet) by 2100. The uncertainty reflected in that range relates to whether greenhouse gases continue to increase, thus accelerating the rate of melting of land-based ice in the polar regions.

Some changes can be expected regardless of the human response over the next 80 years. For example, one analysis looking at Whidbey Island suggests that there is a 99 percent chance that by 2040 — just 13 23 years from now — sea level will be at least 2.4 inches higher than today with a 50 percent chance that it will be 7.2 inches higher. After 2040, the tides will keep rising even faster. Take a look at the related story “Average high tides are creeping higher in Puget Sound.”

John Vechey of Orcas Island, who I featured in my story, took sea level into account when deciding whether to remove his bulkhead while seeking to improve the beach for family activities and for the environment. His solution was to move his house and give the beach more room to function naturally.

Moving a house will not be the answer for everyone, but I can safely say that everyone should consider their long-term picture before making any investments that will last a lifetime — and that includes changes to the shoreline.

I believe it is generally possible, certainly with professional help, to calculate elevations for the house and any low spots on the property, add one to four feet above the current high-tide mark, and then consider tidal surge, which is the wave height caused by weather conditions. In some counties, professional help is available if you are considering whether to remove a bulkhead. Check out the “Shore Friendly” website and “Resources in Your Area.”

At this time, future sea levels do not enter into regulatory considerations about where a person can build a house. One problem is the uncertainty surrounding the amount that sea levels will actually rise. But some environmental advocates say it is time to require additional setbacks, not only to protect the environment as tides push back the natural beach but also to protect homeowners from future losses.

For some people, sea-level rise is a distant worry, but for others the threat is just around the corner. I was reading this morning about how high tides are already affecting Naval Station Norfolk. Check out “Rising Seas Are Flooding Virginia’s Naval Base, and There’s No Plan to Fix It” by Nicholas Kusnetz of Inside Climate News.

A new Government Accountability Office report, released yesterday, cites estimates of future property damage totaling between $4 billion and $6 billion per year in the U.S. as a result of sea-level rise and more frequent and intense storms. The report outlines the need for a coordinated federal response.

Sen. Maria Cantwell discusses the new GAO report and calls for better planning in the video below.

Leave a Reply

Your email address will not be published. Required fields are marked *

Before you post, please complete the prompt below.

Is water a solid or a liquid at room temperature?