In completing the purchase of Sears Island and shifting the immediate focus from cargo to cruise ships, the state again is driving home an important point — 940 acres is room enough for both nature and commerce.

The tentative plan presented by Gov. Angus King and Transportation Commissioner John Melrose Wednesday to direct initial development toward tourism is a good step toward a goal of multiple use that must be reached if the island is to become anything other than high-priced subdivision lots. Environmentalists and economic developers must work together from the start to achieve that balance.

That did not happen last time. Twenty years of state planning and nearly $20 million invested by state taxpayers for a container-cargo terminal to take advantage of the island’s deep water and rail access, along with concession after concession to recreational users, could not overcome the persistent lawsuits and increasingly specious objections thrown up by environmental groups, led by the Sierra Club. The project was not killed by a lack of merit, it merely was stalled to death.

The causeway is built, the dredging is done, the virtually non-existent eelgrass that was the last straw last time still is as much a red herring as ever. A state-owned pier for ferries and cruise ships, a passenger rail terminal, private investment in lodging and other tourist amenities, and the largest chunk left wild makes an attractive package of balanced use.

For now, expansion of the region’s cargo capacity is being directed a stone’s throw across the bay to Mack Point. That’s fine, but that privately owned mainland site already is jammed with industrial uses and an upgrade that may go to voters in a bond issue request next sping merely buys time. The governor made it clear Wednesday that cargo may still have a place on Sears Island — it’s a given that all who want to guide the island’s future must acknowledge from the start.

Last time, opponents of the cargo terminal fondly called Sears Island Maine’s largest undeveloped island and a natural treasure. It is that, but it also is an chunk of land already surrounded by industry in a region that has long earned its living in the shipping trade. Sears Island is big enough for both.