I only moved to the Seattle area in 1996 so the Growth Mangement Act was already in place, but I knew there was a reason I dislike Maria Cantwell so much:
As a state representative, she helped write the Growth Management Act of 1990, which required cities to develop comprehensive growth plans, and she negotiated its passage.
Here is a study of the effect of Growth Management Policies from Florida
The literature portrays a social class bias in the adoption of growth controls (Navarro and Carson, 1991; Bollens, 1990;
Donovan and Neiman, 1992). Communities with a higher per capita personal income and educational attainment levels and smaller poverty populations are expected to have a greater commitment to growth management land use controls.
There is near consensus that regulatory policies raise housing prices because they reduce the supply of land or its developmental potential (Dowall, 1980; Denzau and Weingast, 1982; Landis, 1992; Engle, Navarro, and Carson, 1992).
Gruen (2001) contends that four kinds of actions (or inactions)
are primarily responsible for the lack of equilibrium in the housing market: (1) limitations on development; (2) imposition of high fees and exactions; (3) limitations on the use of vacant land for housing; (4) reduced capital funding for transportation, water, and waste treatment infrastructure.
So basically we have a law that is socially biased against the low to middle income groups and that raises housing prices in it's area of effect thanks to Senator Cantwell.