After almost five years, dozens of hearings, hundreds of public comments, multiple legal challenges, and enough environmental and legal analysis to fill a small apartment, the Seattle City Council is finally poised to pass the citywide Mandatory Housing Affordability (MHA) plan, which has been in the works, as part of the city’s Housing Affordability and Livability Agenda, since 2014.

The city council passed the plan out of committee on a unanimous vote last Monday, February 25, a fact that is remarkable in itself. The council spent hours debating some final nuances of the legislation (and ultimately rolled back upzones in some areas), but all nine council members fundamentally agreed on the overall goal of building more housing, including affordable housing, throughout the city—a notable turnaround from just four and a half years ago, when a Seattle Times story on a leaked draft of the plan sparked so much backlash that then-mayor Ed Murray decided to scale back the proposal.

MHA allows developers to build taller, denser residential and commercial buildings in the city’s multifamily and commercial areas and urban villages—neighborhood centers, typically located along major arterial streets, that have long been designated for future growth because of their proximity to transit, jobs, and services. It also expands some of those urban villages to allow second houses, townhomes, duplexes, and small apartment buildings on about 6 percent of the land that is currently zoned exclusively for detached single-family houses.

The rest of the city’s single-family areas, which occupy about 75 percent of the city’s developable residential land, will be untouched by the changes. This was a major point of contention during the MHA deliberations. Urbanists pointed to Seattle’s history of redlining and studies showing that exclusive single-family zoning perpetuates racial and income inequality to argue that the city should get rid of single-family zoning altogether.

In exchange for greater density, developers are required to build or pay into a fund to build housing that is affordable to people making less than 60 percent of the Seattle median income—currently $48,150 for a family of two. The city hopes that MHA will result in 6,000 units of new low-income housing over the next 10 years. The plan has already been partially implemented—six neighborhoods, including downtown, South Lake Union, and the University District—were upzoned two years ago. The legislation the council has been considering for much of the last year concerns the rest of the city.

The plan, on the whole, is modest, and its impacts won’t be visible right away. In most places, it bumps land up just one or two zoning designations—allowing two-story stacked flats, for example, in areas where only townhouses are allowed today, or raising the maximum height for apartment buildings from 30 feet to 40. It also restricts most of the biggest changes to major arterials, which already tend to be pretty dense. And since many of the changes in MHA are subtle (houses built under a new type of zoning called Residential Small Lot, for example, may be virtually indistinguishable from houses built under the previous zoning), people living in single-family areas that get upzoned might not even notice the difference.

The city has prevailed against legal challenges to the plan so far. The most recent of these was in November, when a city hearing examiner ruled against neighborhood activists who claimed the city didn’t do a sufficient environmental analysis of the proposal. But the final legislation does include a “clawback” provision, supported by MHA opponents and sponsored by West Seattle council member Lisa Herbold. It states the council’s intent to invalidate any upzones implemented under the plan if a court finds MHA’s affordability requirements invalid in the future.

This was another point of contention. Opponents said including the clawback provision in the bill was an invitation to lawsuits, while proponents argued that the provision ensured that developers wouldn’t get “something for nothing”—that is, if a court ruled against the city’s affordable-housing requirement, they wouldn’t be allowed to build denser housing anyway.

The full council is expected to approve the final MHA plan on March 18.