Overview
Seattle's Mayor and two City Councilmembers are members of the Growth Management Planning Council of King County (GMPC). The GMPC is a body of elected officials from across the county that oversees implementation of the state's Growth Management Act, making decisions about where and how new households and employment should be accommodated. The comprehensive plans of all the cities in the county, and of the county itself, must be consistent with the GMPC's decisions.

Staff in DPD's Comprehensive and Regional Planning Unit provide support to the City's GMPC members and to the GMPC as a whole. For more on the GMPC, visit their website.

Recent GMPC Work
In 2002 the GMPC was engaged in important work on both buildable lands and growth targets, including the housing and job targets adopted in 2002. These activities are summarized below.

Buildable Lands - The Growth Management Act requires cities and counties to report on development activity that occurs within their jurisdictions. Each city and county must compile information about:
- new housing units
- square feet of new non-residential floor area
- average density of new developments in each zoning category

The term 'buildable lands' comes from the requirement that jurisdictions must also calculate the amount of remaining buildable land and how much more development the zoning can accommodate on that land.

In King County, where there are 39 cities ranging in size from the 570,000 people in Seattle to the 200 people in Skykomish, one challenge has been to come up with ways to report on activity in these very different environments in a comparable way. Another challenge that faced many of the individual cities, including Seattle, was collecting the information in the first place, since systems designed for recording building permits were not always developed with the idea of pulling this kind of data out of them.

DPD's Comprehensive and Regional Planning staff was responsible for extracting data about units, non-residential square footage and densities from the city's permit tracking system and for calculating the remaining amount of buildable land and development capacity in Seattle. The capacity estimates shows that the City could accommodate about 118,000 additional housing units and about 325,000 additional jobs.

King County staff has compiled the data and analysis performed by all the cities into a single report and has submitted that report to the state. The report, which includes Seattle's data, can be viewed in the Buildable Lands Report on the King County Office of Regional Policy and Planning website.

Growth Targets - The principal requirement of the Growth Management Act is that cities and counties must prepare 20-year plans to accommodate the population forecasts provided by the state Office of Financial Management. OFM first provided population forecasts for planning purposes in 1992. OFM provided new forecasts in 2002 that extend an additional 10 years into the future.

The new OFM forecasts showed that the state is expecting a much slower rate of growth in King County for the next 20 years than the forecasts prepared 10 years ago. The 2002 forecasts suggest that the county's population will grow only half as fast as projected 10 years ago.

DPD's Comprehensive and Regional Planning staff participated with a group of planning directors from many other jurisdictions in King County to help devise a way to distribute the population forecast across the county. During these discussions, the group had to contend with issues such as whether the region would pay for infrastructure in jurisdictions where growth was expected to occur, or whether cities should have to change their zoning so that they could accommodate higher amounts of growth.

The group recommended a method for distributing population growth that recognized the importance of locating employment and housing near each other. The method also recognized the differences in the types of households found in different regions of the county.

The first step in the method divided the urban portions of the county into four regions:

• Seashore - where Seattle is located, also includes the cities and unincorporated portions of King County between Lake Washington and Puget Sound.
• South County -cities and unincorporated portions of King County south of Seashore, all the way to the county line.
• East County - cities and unincorporated portions of King County within the urban growth area, east of Lake Washington and north of Renton.
• Rural Cities - six cities that are islands within the rural area.

These areas are shown on King County's Urban Sub-areas Map (file in PDF format).

The group then determined the proportion of future employment that the Puget Sound Regional Council (PSRC) has forecast for each of these regions and assigned the same proportion of the population forecast to each region. For instance, the PSRC forecast expects the Seashore region to take 33% of the county's new jobs over the next 20 years, and so was assigned 33% of the OFM population forecast for the county.

Because jurisdictions regulate growth by housing units and because it is easier to monitor growth by counting units than people (between Census years), the group converted the population forecasts for each region to housing units by using estimates of future household sizes. Different household sizes were used for each of the four regions, based on data observed in the 2000 U.S. Census, which showed two significant facts about household size:

1) the average household size in the county remained essentially the same as it was in 1990, defying a decades-old trend of continuous decreases;

2) average household sizes were quite different in the four different regions - smallest in Seashore and largest in the rural cities.

Finally, planning directors from each region met to allocate the households to each jurisdiction within the region, using factors such as the location of urban centers and other employment locations and the presence of existing zoning capacity.

In September 2002 the GMPC approved the household growth targets and accompanying employment targets developed by the staff group. These targets represent the amount of growth each city must be able to accommodate by the year 2022. This means that cities must have zoning and at least plans for infrastructure (roads, water, sewers, etc.) that would allow the targeted growth to occur.

The adopted targets, shown on the table below, will be incorporated into the comprehensive plan updates that all the jurisdictions are required to perform by December 2004.