Island County, Washington

Island County, population 85,141 (2019), consists of islands in Puget Sound, thirty miles northwest of Seattle, Washington. The County instituted an Interim Zoning Ordinance in 1966 which remained in effect for 18 years. In 1984, the County adopted a new zoning code designed to preserve natural resources and rural character partly by significantly reducing allowable development densities.

At the same time, the County adopted a TDR program to compensate property owners for this downzoning, which cut maximum allowable densities by up to one-eighth of their prior limits. For example, some properties which had been zoned at a density of one dwelling unit per 2.5 acres were rezoned to a density of one dwelling unit per 20 acres. In addition, the TDR program was designed to discourage the County Planning Commission from granting exceptions to the new zoning regulations based on the economic hardships caused by this downzoning.

The first TDR program was underutilized and, in 1998, Island County replaced the 1984 TDR program with an Earned Development Unit (EDU) system designed to address the shortcomings of the original program, particularly the lack of receiving areas.


In the 1984 Island County TDR program, sending sites were lands classified as Agriculture, Forest Management, wetlands, tributary streams, and their associated buffers. Owners of land in these sending areas could apply for certificates of development rights at the rate of one TDR per gross acre of sending site.

This transfer rate was significantly higher than the density allowed for development on the sending site. The Agriculture and Forest Management zones, for example, allowed on-site development at a maximum density of one dwelling per 20 acres; this transfer ratio of 20:1 was one of the highest in the nation, creating a significant motivation for sending site owners to transfer rather than build in this zone.

In the original program, potential receiving sites consisted of land classified Residential, Rural Residential, Agriculture, and Forest Management. In the Agriculture and Forest Management zones, the maximum density was one dwelling unit per 20 acres. However, when land parcels in these zones were proposed for projects using TDR, the maximum allowable density doubled to an average of one unit per ten acres, a 100 percent bonus. Similarly, the Rural Residential zone had a base density of one unit per five acres. However, TDR receiving sites of 20 acres or more were allowed up to an average of one unit per acre and sites of 100 acres or more could receive up to an average of six units per acre, a bonus of 2,900 percent. In the Residential zone, the base density of 3.5 dwelling units per acre could be increased to as much as an average of six dwelling units per acre for TDR receiving sites, a 71 percent increase.

Despite attractive transfer ratios and density bonuses, Island County was not satisfied with the number of transfers achieved under the original TDR program. In 1998, the County adopted a new comprehensive plan and replaced the original TDR program with a new implementation system called Earned Development Unit, or EDU.

In the EDU system, sending areas must be zoned Commercial Agriculture or CA. The County must approve a Farm Management Plan before an owner can transfer EDUs from CA-zoned land. In general, the Farm Management Plan must enhance the agricultural viability of the land and conserve prime soils. In particular, the Plan can only be approved if a Conservation Easement in perpetuity is recorded on at least 85 percent of the parcel subject to the Management Plan. EDUs are added to the base density and allocated at the ratio of 0.20 EDU per acre under Conservation Easement.

EDUs can be transferred to sites zoned Rural, Rural Agriculture, Rural Forest or Commercial Agriculture in accordance with an approved Management Plan and the following standards in effect in August 2011.

  • EDUs can be used on no more than 15 percent of the receiving site and cannot be located on prime agricultural soils.
  • Receiving sites zoned R, RA or CA must be in one ownership when the Management Plan is approved.
  • EDUs may not be used in combination with density bonus provisions.
  • In R and RA zones, EDU can increase base density by more than 100 percent.
  • Development using EDUs must be clustered and must be served by Rural Governmental Services.

EDUs offer the following development bonuses.

  • One single-family residential lot per EDU.
  • Campground: one EDU per acre
  • Boat launches: one EDU per lot
  • Country inn: one EDU per 2,500 sf of gross floor area
  • Churches: one EDU per 2,500 sf of gross floor area
  • Gun clubs & shooting ranges: one EDU per acre
  • Fire stations: one EDU per lot
  • Mini storage: one EDU per 2,500 sf of gross floor area
  • Restaurants: one EDU per 2,500 sf of gross floor area
  • Model hobby parks: one EDU per lot.

Program Status

Under the original 1984 TDR program, Island County anticipated requests for receiving site designations within a proposed Zone of Influence and proposed Urban Business Centers. However, the Zone of Influence and the Urban Business Centers were never adopted. Consequently, the original TDR program had to be implemented entirely through Planned Residential Developments (PRD). Furthermore, under the original program, the Planning Commission and the County Board had to determine, on a site-specific basis, the amount of additional development which would be allowed on the receiving site as a result of transferred rights. Also, as explained by Dwain Colby, Island County Commissioner, developers were often not interested in gaining the additional density offered through the original TDR program; consequently, the demand for transferred development rights was low.

Nevertheless, the original Island County program had several factors found in the most successful TDR programs. The sending site owners were encouraged to sell their development rights by a transfer ratio of up to 20:1. The receiving site owners could significantly increase the density of their projects by using transferred development rights. In fact, in some cases, the TDR bonus yielded a 2,900 percent increase in density. Due to these factors, 149 development rights were certified and 87.74 acres of land were protected by conservation easements between 1984 and 1995. During this time period, 18 TDRs were used in three planned residential developments. An additional 28 dwelling units were authorized on receiving sites.

As reported by Assistant Planner Michael Schechter, the new EDU program, adopted in 1998, had not yet been used as of January 2001.