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Should thousands of trees be removed from residences in Thurston County?

That sounds like a crazy question! Most people love trees, especially mature ones. Besides being beautiful, trees absorb the greenhouse gas carbon and emit oxygen, reduce air pollution, cool houses and neighborhoods in summer, reduce urban heat sinks that cause deaths from cardiovascular disease, retain soil moisture, reduce flooding and stabilize slopes.

But the new Wildland-Urban Interface Code (WUIC) will result in thousands of trees being cleared. It applies to Intermix/Interface and wildland areas designated by a map published by the Washington Department of Natural Resources.

In Thurston County the WUIC will apply everywhere that people can live, including rural agricultural areas, except the urban cores of Olympia, Tumwater, and Lacey. In fact, part of Olympia, half of Lacey, two-thirds of Tumwater and all of the small towns in the county are designated as Intermix/Interface areas.

The WUIC requires all new residences to use expensive ignition-resistant materials and construction methods. For existing residences, the code will apply when the owner asks for a permit to do exterior construction, such as roofing or adding an extension.

The code also requires 30, 50 or 100 feet of defensible space around residences. The amount of defensible space required is determined by the slope of the land, access roads, access to water, and proximity to any kind of dense vegetation, from meadows and fields to prairies and parks.

While the WUIC allows trees in defensible spaces, each tree canopy must be 10 feet from other tree canopies, buildings, and overhead electrical wires. The result? Small lots will have at most two to four trees. Over the years thousands of trees will be lost. In addition, groves of trees are less susceptible to drought, wind damage, and disease, but this code will eliminate them.

The purpose of defensible space around a house is to slow a wildfire so firefighters can defend the residence. However, recent wildfire science shows that the best defense is to use fire-resistant materials because embers and firebrands can be blown thousands of feet. Clearing trees is not effective except in a narrow zone five to ten feet around a house.

This WUIC has other problems. Maybe creating defensible space was never intended by the state legislature–defensible space is not mentioned in the legislation. According to a letter from the Association of Washington Cities, the code is also confusing and unclear on many points. Even more confusion will result from the code’s conflicts with seven state laws and hundreds of local ordinances. These laws and ordinances protect trees because of the many services they offer us, services listed in the first part of this article.

Many people have questioned the accuracy of the WA DNR map that designates interface/intermix and wildland areas where the code will apply. These designations are based on population density, not where the risk of wildfire is greatest. The map has “definition” only down to three miles, so it will be difficult to determine whether a particular land parcel is within the intermix/interface zone or not.

This poorly designed code is the result of well-intentioned legislation to protect people and their homes from wildfires as global heating brings more drought to Washington over the fifty years. “Home-hardening” with fire-resistant materials will offer that protection. Since homes last fifty years or more, it makes sense to start requiring these materials now.  However, we need to hold onto our trees as long as possible to mitigate climate change, reduce drought and bring down summer temperatures.

Fortunately, the State Building Code Council can buy time to research all the unintended consequences of the WUIC.  At their meetings on November 17 and 28, 2023, they can pass an emergency rule to remove the defensible space requirements or to pause the whole code.  Then the SBCC will have three years in their regular code creation cycle to work on the WUIC.

Your voice can be one of those urging the SBCC to declare an emergency.  Sign the petition at

Charlotte Persons is a life-long environmental activist and a contributor to WIP since 2021.

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