Written by Olivia Kwan, Policy Intern Forterra
Farms and forests are disappearing as cities expand outward. But land is finite—and once it’s developed, it rarely returns to working farms and forests. While development is managed by the Growth Management Act, Washington state is still seeing a high preference towards outward expansion of cities instead of infill development according to building permit histories. This is a growing concern because land is limited, and as cities continue to expand outward, the natural landscapes that make communities healthier, more resilient, and more enjoyable to live in become increasingly scarce.
One solution to this dilemma is a mechanism called Transfer of Development Rights (TDRs). TDRs are a mechanism which uses sending and receiving sites to conserve land while furthering infill development. TDRs are an effective and actionable tool that has demonstrated success in supporting development, including in Seattle’s South Lake Union neighborhood.
When I first learned about TDRs, I understood the concept, but it was difficult to understand the direct impact it had on communities and cities. Through my research, I learned that by promoting infill development and densification, TDRs can help cities grow, while also minimizing their carbon footprint, increasing social connectedness, and maximizing public services.
Many city representatives and developers we spoke with noted that TDR programs have not been widely adopted because they can be complex to implement, noting issues with timelines, upfront costs, and examples of the program beyond Seattle.
After speaking with representatives from Snohomish, King, and Pierce Counties, I noticed that a recurring challenge was the lack of clear examples demonstrating successful implementation and measurable benefits. I took this challenge and began a research project investigating the importance of TDRs and the impacts of denser development patterns.
To begin, I analyzed historical data from the past five years to better understand how different development patterns have influenced communities and the environment.
The project compared two cities within King County: Sammamish and Shoreline. Both cities lack a history of using TDRs, although Shoreline has recently begun implementing them. Despite this shared history, the two cities have experienced markedly different patterns of growth.
I chose Sammamish and Shoreline because they had similar populations but very different physical land sizes and development patterns. Shoreline has begun prioritizing infill development based on their recent building permits and has a newly adopted TDR program.
Based on findings, the average resident in Shoreline emits around 1.5 megatonnes of carbon dioxide (MtCO2) annually from energy consumption, whereas the average Sammamish resident annually emits around 3.4 MtCO2. Both calculations support the notion that a denser city can contribute to carbon footprint reductions.
I was surprised by how significant the difference was between the two cities. Conversations with professionals in the energy sector helped explain this gap, as they highlighted the substantial energy savings associated with multi-family housing compared to single-family homes which corresponds strongly with both cities building patterns.
Emergency services in more spread-out communities often face greater operational challenges, because they must cover a much larger geographic area than services in more compact, higher-density communities. Directing future growth to existing urban centers through TDRs can improve service efficiency by reducing the area emergency services must cover.
High-density development as a result of using TDRs also provides increased opportunities for spontaneous social interaction. In walkable neighborhoods, residents are more likely to encounter neighbors while walking to parks, shops, schools, or transit stops, helping to build a stronger sense of community. Many walkable cities see an increase in civic engagement since residents find a stronger community identity when they frequently interact with neighbors.
While conducting this comparison, it was interesting for me to see my prior notions exemplified through statistical evidence. TDRs effectively help cities reduce carbon emissions, support vibrant communities, and increase the effectivity of public services through the fundamental principle of increasing densification where there is already infrastructure present. In this way, resources are used more efficiently.
There are many positive benefits to TDRs that could be brought to cities like Sammamish. Growth is inevitable, but the loss of our natural landscapes does not have to be.
By embracing tools like TDRs, we can choose a future where cities grow smarter, communities become stronger, and farms and forests remain protected. The time to shape Washington’s future is now.
