Just since mid-August, newly hired off-duty Honolulu police officers have kept at least 900 illegal hikers from trespassing onto one of Oahu’s most popular outlaw trails: Kaneohe’s Haiku Stairs, also known as the Stairway to Heaven.

The Honolulu Board of Water Supply, which owns most of the land around the more than 3,000 steps that lead to Puu Keahiakahoe at the top of the Koolau Mountains, has been relying on private security guards — without the benefit of police powers — to warn hikers that they were trespassing.

“We still do have a security guard at the base of the stairs to help turn people away,” said Board of Water Supply spokeswoman Kathleen Elliott-Pahinui, “but they can’t cite. They can only tell them it’s illegal and they’re not supposed to be there.”

So the Board of Water Supply last month started using an undisclosed number of off-duty Honolulu police officers at a cost of about $2,000 a week, Elliott-Pahinui said.

Trespassers face maximum penalties that could include citation, arrest, fines up to $1,000, community service of 100 hours or more and jail time.

In order to keep illegal hikers off guard, Elliott-Pahinui declined to say how many officers are in the area at any given time, or when they’ll be there.

“I really can’t talk to specific details,” Elliott-Pahinui said, “but they’ve been very effective in turning people away from the property.”

The officers also have issued 12 motor vehicle citations for violations including expired registrations and insurance.

The move to beef up security comes as the Board of Water Supply continues to hold meetings for a draft environmental impact statement, which is expected sometime in March or April, about the future of the Haiku Stairs.

The Navy installed the original set of wooden stairs in the 1940s to access radio antennas at the top of the Koolau range during World War II. They were replaced by metal ones in the 1950s, according to the Board of Water Supply.

The Coast Guard took over in the 1970s but closed its Omega navigation station in 1991. Even when the stairs were used for official business, they remained off-limits to civilian hikers because of the risk of falls, injuries and lawsuits resulting from the stairs, which get slippery and cold in the Koolau mist.

In 2005 the city rebuilt the stairs again as neighbors continued to complain about trespassers crossing their property, taking up neighborhood parking, causing vandalism, leaving trash and generally disturbing homeowners — especially in the early mornings and near sunset.

While the Board of Water Supply continues to work on the next plan for the stairs, Maurice “Mo” Radke, chairman of the Kaneohe Neighborhood Board, welcomed the extra security.

“It’s a good thing for the people who’ve had repeated trespassing on their property,” Radke said.

Elliott-Pahinui of the Board of Water Supply estimates that Honolulu firefighters made 20 rescues in the area last year — or nearly two rescues per month.

Fire Capt. David Jenkins did not immediately have the exact number of Haiku Stairs-related rescues available Monday, but said Elliott-Pahinui’s estimate sounds about right.

Hikers try to access Haiku Stairs any number of ways, including coming over from Moanalua Valley in order to climb down the stairs, Jenkins said.

“There are multiple routes getting to that area, and there are all kinds of different hazards,” Jenkins said. “It’s extremely treacherous and hazardous.”

When firefighters get a “high angle” or “mountain” rescue call for Stairway to Heaven, the department typically deploys its Air 1 helicopter, a battalion chief “and several firetrucks,” Jenkins said. “It does take emergency personnel and a considerable amount of manpower and assets. When people put themselves in harm’s way, it’s very distressing.”

But HFD will not ask an illegal hiker who gets lost or injured to reimburse the department for the cost of a search and rescue, Jenkins said.

“The Fire Department does not endorse charging for a rescue because we feel it would put both the patient, the people we’re rescuing, and the firefighters and all first responders at greater risk,” Jenkins said. “If someone feels they’re going to incur a fee for a search and rescue, which could be thousands of dollars, it may delay their calling for help when it’s needed. That could make a medical emergency become worse and make the rescue that much more difficult for both the patient and rescuers.”

Instead, Jenkins said the Honolulu Fire Department recommends that hikers enjoy any of the sanctioned hiking trails listed on the state Department of Land and Natural Resources’ website, which can be found here.