People who are willing to pay the price of living on Oahu know the island’s living space is a precious, perishable commodity.

Nobody wants Honolulu to simply let buildings sprout wherever they may, extinguishing what’s left of the island’s beauty. And yet, judging by the recent community testimony on various plans for Kakaako, the Hawaii Community Development Authority is struggling to explain and execute the guiding vision for this area.

The agency holds court over some contentious issues in the region. There is an undeniable need for more housing on Oahu, but with relatively few exceptions, the land set aside for residential development is already built out. So few new homes are being built that the annual real-estate Parade of Homes showcase was canceled for the first time for lack of new models.

Efforts to constrain building outside the urban boundaries, coupled with a widespread fatigue from long commutes from the suburbs, mean that future homes inevitably will come through redevelopment of the city — what planners call "infill."

There are innumerable spots within urbanized Oahu where this infill is happening — the recent proposal for a mixed-use complex at the site of the old Kam Drive-In Theater is just one example — but the crown jewel for developers has got to be Kakaako.

The last, relatively sparsely developed section of Honolulu frontage was left to become what the governor now calls Oahu’s "Third City." Ownership of the properties was scattered, so lawmakers decided that a semiautonomous authority could provide the planning and coordination that was needed.

This was the reasoning behind establishing the HCDA, created by state law in 1976. To the extent that the agency has created a master plan for the area — and so far has reserved the priceless makai area for recreational, educational and other non-residential uses — its existence is justified. But if HCDA allows sophisticated developers to undermine the master plan through exceptions and variances, the public should push back.

Vigilance, by the residents and the agency itself, is essential.

The planning documents for Kakaako set out view corridors along its mauka-makai streets to keep it from becoming too densely packed. Directives for orienting buildings more or less perpendicular to Ala Moana Boulevard were aimed to prevent high-rises from lining up, in tombstone fashion, along streets to capture the best ocean views. This would create Manhattan-esque urban canyons, and it’s not what Honolulu should want for its future.

Sometimes the opposition from neighbors is trumped by other concerns. In the Symphony tower project, for example, a variance was granted because the lot size didn’t easily accommodate the desired mauka-makai building alignment.

By contrast, there was the 803 Waimanu project. After the neighbors raised alarms about its closeness to other buildings, and after HCDA issued a preliminary thumbs-down, the application was withdrawn.

This underscores the importance of residents staying engaged. The commu- nity also must press HCDA to hold more evening and weekend hearings so working people can attend.

Recently, testimony has become more heated and voluminous. The Collection, a development by A&B Properties Inc., and Kamehameha Schools’ Land Block E (Ala Moana and South Street), are two that have drawn concern.

A group consisting primarily of homeowners at the nearby One Waterfront Towers apartments has filed a petition protesting various aspects of the projects. Points of contention include building heights and setbacks, intrusion into view corridors, impact on crowded streets and strains on existing schools, according to the petition.

And, in what is perhaps the most vocal confrontation, residents spoke out for and against the development of a second tower at the 801 South Street project. The tower would provide needed condos priced at "workforce" levels, say its advocates. There’s no guarantee that the units won’t be flipped at a higher price, say some opponents.

If Oahu wants to "keep the country country" on the North Shore and other areas, more density in the urban core is needed. But if Kakaako is to become a well-planned Third City, HCDA needs to hew closely to its master plan.

That plan was drawn with community input. Departures from those carefully inked blueprints should come rarely, and with clear benefits to the public.