Sammamish, population 45,780 (2010), lies east of Lake Sammamish in King County, Washington, only 12 miles east of downtown Seattle. Despite its location within this major metropolitan area, a surprisingly large proportion of Sammamish remains in farms, forestland and other rural open space.

In 2008, Sammamish adopted its Town Center Plan, which included policy support for a TDR program aimed at preserving farmland, forest land, open space and wildlife habitat. In February 2011, the City adopted TDR regulations to implement that policy. These regulations were amended in September 2011 and those revisions are included in the description of Chapter 21A.80 found below.

Receiving area developers can transfer development rights from in-city or inter-jurisdictional sending sites. The in-city sending sites include underdeveloped or partly developed parcels within the Thompson sub-basin, the Inglewood Sub-basin, the erosion hazards special district overlay or the wetland management area special district overlay. Inter-jurisdictional sending sites include sending sites within unincorporated King County indentified in an interlocal agreement with King County or land identified in an interlocal agreement with another jurisdiction.

Sending sites must provide at least one of the following public benefits:

• Open space adjacent to a City park or other open space
• Wildlife habitat for threatened or endangered species
• Protection for sensitive sub-basins or environmentally-critical areas
• Farmland
• Forestland

In addition to location and public benefit, qualified sending sites must have unused development potential. For in-city sending sites, that means the ability to accommodate additional dwelling units based on the minimum lot size requirements of the underlying zoning district. (The code notes that every legal undeveloped lot has at least one unused development right.) For inter-jurisdictional sending sites, the TDRs are determined by the interlocal agreement.

The owners of qualified in-city sending sites can participate by submitting application. The City then issues a TDR certificate letter of intent with the number of available TDRs on the site. These letters of intent have no value until the property owner records a permanent conservation easement that not only limits future development but also limits the site to uses consistent with the required protections if the identified public benefit. When such a conservation easement has been recorded on the sending site, the City issues serially numbered TDR certificates. The interlocal agreement establishes the procedures for creating and transferring TDRs from inter-jurisdictional sending sites. The City cannot issue more than 630 TDR certificates.

In 2011, all receiving sites are located within the Town Center, specifically commercial properties in Zone A and residential properties in Zones A, B, C and D or the Town Center. However, the code has a placeholder for the inclusion of additional receiving areas at a later date. Chapter 21.B.25 establishes baselines and maximum densities for the Town Center residential districts, which vary by zone as follows:

Zone A: baseline 16 dwelling unit per acre and maximum 40 units per acre via TDR

Zone B: baseline 8 dwelling unit per acre and maximum 20 units per acre via TDR

Zone C: baseline 4 dwelling unit per acre and maximum 8 units per acre via TDR

Zone D: baseline 8 dwelling unit per acre and maximum 20 units per acre via TDR

The bonus available to receiving sites from TDR varies based on the zoning of both the sending and the receiving site. Consequently, the allowance ratios are established by the following table in which the columns represent the sending site zoning and the receiving sites represent the received site zoning.