The City and County of Honolulu has finally put forward its plan on ensuring that Oahu still has agricultural lands for its future needs. That’s never an easy thing to do, because as a consequence, some powerful landowners will not reap the returns that urban development would bring — far more than the yield of any farm.

But it’s worth celebrating that the administration did at last issue the “O‘ahu Important Agricultural Land Mapping Project,” a document that identifies the acreage that the city will set aside in perpetuity for agriculture.

Once the Honolulu City Council reviews and adopts it, as it should, the county will have a repository of land with long-term surety about its designated use. That shields it, to some extent, from the speculation that drives up land costs in a state with such a limited supply.

Forty years have passed since the state mandated the identification of an “important agricultural land” (IAL) base through an amendment to the Hawaii Constitution. According to the report, published by the Department of Planning and Permitting, 12,300 acres already have been designated IAL by the landowners through a voluntary petition process.

DPP studied 63,900 more acres and, after evaluating according to criteria set in state law, the agency has identified about 45,400 to be added to the IAL classification. Most is in Central Oahu, with several large tracts on the Waianae coast and in the Koolauloa and Koolaupoko districts.

There are major hurdles yet to surmount before the final maps become enforceable. The Council must review and approve them before the ultimate acceptance by the state Land Use Commission.

During its review, the Council will surely come up against pressure from landowner interests. However, DPP has indicated that the areas mapped as the most important to agriculture were chosen irrespective of ownership. That was based on the set criteria for cultivation suitability, according to the report.

Council members should keep the same quality-matters principle in mind in their review.

Further, state law provides for some landowner incentives for IAL lands and allows for the counties to add their own. Oahu has not yet done so, but part of the coming debate with stakeholders should include discussions about whether and how much to sweeten the pot.

Locking down the land base is a necessary step toward supporting agriculture, but not a sufficient one. Other steps have to follow to overcome myriad hurdles in the path toward reconstituting a successful agricultural sector, once foundational to the islands’ economy.

Gov. David Ige’s administration has adopted a series of sustainability priorities, including one to double Hawaii food production by 2020. That target date — right around the corner — still appears on Ige’s website, but it’s more aspirational than feasible.

Among the state’s current challenges: Firm figures to gauge homegrown food production are lacking; accurate baseline data are critical in documenting the deficiencies and charting the way forward.

The farming lobby also has pointed out other impediments in making agriculture more lucrative. The industry is torn by conflict over cultivation of genetically modified organism (GMO) crops. Labor shortages are acute. Unfunded mandates, such as federal food-safety rules imposing strict produce handling procedures, discourage startup farming enterprises.

Programs to promote public and private investments in the infrastructure of farming, such as meat and produce processing and packing, also would enhance the profit potential.

A lot of work remains before Hawaii can see agriculture thrive as needed. Adopting a safeguard for Oahu’s best farming lands, however, represents a necessary giant step toward sustainability that must not be delayed.