It’s all upside potential for the Board of Water Supply as it seeks to redevelop its Beretania Street site. Envisioned is a scenario that includes a 10-story structure on a 3-acre parcel the BWS currently uses as employee and fleet parking lots; that vertical growth is allowed under the site’s existing zoning for medium-density apartment heights.

What specific project emerges is yet to be determined: The BWS expects to solicit bids from private developers in the latter half of next year, in hopes of monetizing about half of its 6.4-acre property to help generate revenue to offset expenses. It’s a sensible plan to try to optimize this underutilized, prime chunk of urban real estate — but one that evidently is harder to realize than it seems: A 2013 effort that targeted nearly the entire property fell through.

This time around, the BWS is offering about 3 acres for a maximum 65-year lease, and a few scenarios are emerging: a 1,155-stall parking garage, or a 605-stall commercial parking structure with either 312 senior rentals or a 266-unit assisted-living facility.

One of the two latter housing scenarios sounds encouraging, given the high costs and shortage of homes, not to mention the growing needs as Hawaii’s population ages. As with all such land-use opportunities and choices, the BWS and prospective developers can — should — be part of crucial housing solutions.