The popular, but illegal, staircase up a Windward Oahu mountainside nicknamed “Stairway to Heaven” has a chance to live on under city ownership.

Leaders of the Honolulu Board of Water Supply voted unanimously Monday night to accept a plan by Mayor Kirk Caldwell to acquire more than 200 acres surrounding the Haiku Stairs from BWS and have the attraction managed responsibly by a contractor.

But the city agency governed by an independent board gave city leaders a deadline — 18 months to complete an acquisition or else BWS will proceed with a preferred plan presented by staff to remove the stairway in Kaneohe at an estimated cost of $1 million.

The decision followed a flood of testimony from about as many people as there are stairs — close to 3,800 testifiers compared with 3,922 steps — and the overwhelming sentiment was to maintain the more than 50-year-old metal stairway.

Of the testimony, nearly all by email, a little over 3,600 people voiced support to keep the stairs.

Supporters often called the apparatus a historic treasure, comparing it to recognized wonders of the world, and many said it can be managed appropriately to mitigate a longtime problem of nearby residents being disturbed by hikers cutting through their property to access the stairs that have had no illegal access for more than 30 years.

“It would be a terrible, terrible loss,” Matthew Kievlan told the board by phone Monday during a nearly 4-hour meeting where people testified by phone and a video camera in the agency’s lobby.

About 180 people urged the agency to remove the stairs, and included many residents who live close to the base of the hike and for decades have had to deal with trespassers crossing their property and sometimes causing trouble.