The World Conservation Congress (WCC) has yet to begin, but when it concludes Sept. 10, about $12 million in state taxpayer dollars will have been spent on the high-profile international meeting.

Huge investments of public dollars are being made. In fact, the city is expected to foot $3 million to $4 million in security costs for the 10-day event.

While the importance of the premier conference of the International Union for Conservation of Nature (IUCN) and its overall goals are not in question, the public needs assurance that the expense of attracting and hosting world-class events such as the WCC produces a significant return on investment.

The only way to do that is to seriously assess, after all the dust settles, whether the overall costs and labor were worth hosting the WCC — which is being held in the United States for the first time when it comes to Honolulu Sept. 1. A postmortem look into the accounting of the estimated $12 million in taxpayer dollars spent for hosting could help determine whether bringing future international events of this scale to Hawaii is indeed beneficial. Such an assessment should be made available for public discussion.

The last time Hawaii hosted an event on such a grand scale was the 2011 Asia-Pacific Economic Cooperation (APEC) forum. APEC drew worldwide attention and brought roughly 15,000 visitors, including 2,000 journalists and heads of state from 21 member nations. That event was estimated to have pumped $120 million into Hawaii’s economy — a huge shot in the arm.

But the draw for WCC is about half that of APEC: Some 8,000 visitors, including 5,000 attendees and 200 journalists, are expected to generate an impact of $62 million. Conservation is a major international issue, but beyond local policy officials, it’s doubtful the conference itself has mass appeal. The Hawaii host committee, for instance, reports a fundraising shortfall of $500,000 to $1 million.

Colin Moore, director of the University of Hawaii’s Public Policy Center, said mayors and governors like to associate themselves with these blue-chip conferences, “but it’s not the bread-and-butter issues that the public cares about.”

Still, taxpayers end up footing the bill.

The state Department of Land and Natural Resources (DLNR) said that all state funds are going toward logistics of WCC hosting, including translators, interpreters, professional congress organizers, IT, audio visual, insurance, security and first aid.

Further, security for APEC cost the city $8.5 million, of which $4.5 million was reimbursed through a federal grant. For WCC, though, the city will have access to only $475,000 in federal funds to offset overtime costs, according to Melvin Kaku, director of the city Department of Emergency Management.

The city estimates WCC security costs will be $3 million to $4 million, with overtime alone for the Honolulu Police Department expected to reach $455,000. DLNR said the city will be handling its own security costs — however, as host of the WCC, the state should have included some reimbursement of security costs to the city.

“The city has not reached out to the state of Hawaii about the possible transfer of funds to cover the security costs associated with hosting the WCC,” city spokesman Andrew Pereira said in an email. “That is likely to happen sometime this week.”

If the state intends to host more large-scale international conferences in the future, it will have to do a better job of establishing public-private partnerships so that taxpayers aren’t forced to pay nearly the entire bill — and factor in costs incurred by affected counties. Without robust community support and the money that brings, it’s hard to justify spending millions of dollars when weighty issues such as homelessness, education and transportation are competing for those very funds.