Proposed zoning changes should be dependent upon the developer ensuring some affordable housing.

The redevelopment of the Portland Co. is a significant opportunity to burnish Portland’s “most livable city” reputation. But to ensure that the new development reflects the cultural diversity and egalitarian values of the city as a whole, the city should not approve the necessary zone change until it includes a guarantee that a significant percent of the new residential units will be affordable.

The 10-acre Portland Co. complex is among the most desirable sites in New England because of its stunning panoramic views, its historic structures, its proximity to trendy Munjoy Hill and the Old Port and its access to the city’s outsized cultural amenities. The housing units there will command top regional prices of well over $1 million. While not a concern for the developer, it should be a concern for the residents of Portland because of the likely identity of the new inhabitants.

Over the past 20 years, Portland has attracted diverse new residents, many from around the world. They have dramatically enriched the cultural life of Portland; the quality of our schools, our arts and our cuisine, and the ambiance of our community.

In contrast, if the private market operates unfettered, the new Portland Co. housing will only be within the price range of very wealthy individuals.

Few of them will be from Portland or Maine, and given the demographics of the very wealthy, they are unlikely to be culturally or ethnically diverse. They may not be eager to integrate with the broader population, preferring instead to be a quasi-gated community.

Moreover, it seems unlikely that these new wealthy inhabitants will use Portland as their primary residence. Many will not be interested in wintering over in Portland, and will have the resources and, perhaps, the tax incentives to live elsewhere a majority of the year. A substantial part of the residences would likely be deserted for a significant part of each year.

The city’s comprehensive plan envisions that Portland should be a lively, year-round community. A commitment to include low- and moderate-income housing in the new development would move it closer toward this goal and benefit Portland as a whole.

Requiring a quarter of the units to be priced for and reserved for low- and moderate-income families as their primary residence would increase the stock of worker housing, increase the likelihood of a mix of cultures and lifestyles in the development, and ensure some year-round occupancy. Additionally, the development would attract market-rate inhabitants who are comfortable living in a community with a varied population; wealthy individuals seeking exclusivity would look elsewhere.

A requirement for the developer to include a range of affordable-housing units would be consistent with the Workforce Housing Study just completed by the Greater Portland Council of Governments.

That study found that the local housing market is not producing enough housing for those residents making below Cumberland County’s median household income of $58,500.

It also found that family-sized units are proportionately less affordable than other rental units. And it found that new high-end housing brings with it the need for housing for those with lower incomes to provide workers to service the high-end housing.

In a memo summarizing this report, city staff found “much merit” in an inclusionary approach that would require that all new residential developments over a certain size include a substantial portion of low- and moderate-income housing units.

Representatives of the developers have, on occasion, said that they may not be opposed to including some affordable housing in the Portland Co. complex.

But regardless of the current owners’ good reputation, this is not a commitment that should be left to an informal understanding. The current owners may not be the ultimate developers. Any commitment to include a certain percentage of affordable housing should be converted into a legal requirement.

To develop the site for commercial, hotel and/or residential use, the owners need the city to include the property in the B6 mixed-use zone, or they need to seek conditional rezoning under the Waterfront Special Use Zone.

No provisions in the B6 zone would empower the city to enforce a developer’s commitment to include affordable housing.

But entering into conditional rezoning under the existing zone could allow the city to enforce an agreement with a developer to include a certain percentage of affordable-housing units in this or any other development.

For the sake of making this new Portland Co. complex residential neighborhood truly a contributing part of Portland, the city should not approve a zone change until it includes an enforceable affordable-housing component.