The 75-yard-long steel trestle maintained by Wailuku Water Co. starts from the back of the center and crosses over the river and onto a bank above Kepaniwai Park. The bank, however, has completely eroded away and a concrete slab walkway to the span has been undermined.

“That used to be ground on the bank,” company President Avery Chumbley said Wednesday. “The water has totally undermined and washed away the entire bank. That sidewalk is hanging in midair.”

The gate to the bridge is locked and signs have been posted warning locals and visitors. They say “Danger! Bridge closed due to storm damage” and “Unsafe!”

Large sections of the bridge railing on both sides are bent, and big roots have been exposed due to the erosion.

A sign warns hikers to stay off a popular footbridge spanning Wailuku River on Tuesday evening. The Maui News / MATTHEW THAYER photo

Some visitors were seen climbing over the gate and trying to hike up the river to Iao Valley State Monument recently. The state park closed earlier this month for repairs from a flood last year and is expected to reopen Dec. 16.

Jeeyun Lee, executive director of the Hawai’i Nature Center, said the bridge is too dangerous to cross. The center uses the bridge to access a conservation easement of 31 acres owned by Wailuku Water. The land was conveyed for the center’s use in the early 1990s to teach students environmental conservation.

“I really have to go and take a look and assess the damage to see what I’m dealing with,” Lee said Wednesday afternoon. “But I know it’s not safe right now.”

This is the second time in two years that the bridge has been closed due to flooding and erosion. Last year’s massive flood damaged the bridge and shut it down for a couple months for repairs.

Lee said the closures of the bridge following the September 2016 flood — and the nearby Kepaniwai Park — were a “really tough time for us.” She said their property was not damaged, but the closing of the county park and access for seven months through April stopped the center from busing students in for programs.

The concrete foundation supporting the end of a footbridge and irrigation pipe spanning Wailuku River is undermined in this photo taken Wednesday morning. The support was damaged after heavy rains early Tuesday morning that caused the river to swell. The Maui News MATTHEW THAYER photo

“We ended up partnering with other groups, like Maui Nui Botanical Gardens, and rescheduled students for spring semester” earlier this year, she said.

Lee said the bridge has drawn “hundreds more a day than normal” since the state monument’s closure upstream. She said one of their student’s parents even helped reinforce the bridge in the summer for the increased traffic and to ensure its safety for students this fall.

“We’re a small nonprofit, so we’re not setup to police the bridge,” she said. “We have safety concerns for the general public, which is why we took the time to post the signs.”

The center, which averages 20 to 60 students from public and private schools per visit, utilizes the bridge two to three times a week during the school year, Lee said. Since its inception in 1981, the center has served more than a million students on Maui and Oahu. The Maui center also hosts birthday parties and is available for overnight rentals and private programs for groups.

Chumbley could not estimate the cost to repair the trestle and did not know how long it would take for repairs. He did not believe the large pipe beneath the trestle — that also supports it — was damaged but planned to do further assessments with a team today.

Gov. David Ige (second from right) walks across a footbridge near Kepaniwai Park while touring storm damage on Sept. 22, 2016. That footbridge currently is unsafe after Wailuku River erosion from Tuesday morning’s storm. The Maui News MATTHEW THAYER photo

The bridge initially was built between 1910 and 1920. The pipe has been replaced at least once, Chumbley said.

Tuesday’s thunderstorm caused other damage to Wailuku Water’s systems, including to the Spreckels Ditch in Waihee and to the Waikapu Diversion, Chumbley said. He said no water was flowing from the diversion, which is completely filled by debris and sediment.

“There’s no flow coming out of that tunnel right now, so it’s all plugged up,” he said. “It’s not safe to send the crew up there right now, though, because it might flow still.”

Chumbley said his biggest concerns are further erosion during large floods, like the one Tuesday, and continued damage to the company’s systems by debris loosened by last year’s flood. He also had concerns about trespassers accessing the bridge that sits on private property.

“We’re going to have to figure out some way to block access at that small gate on the north side of the trestle,” he said. “Even though they’re trespassing, we have no waiver of immunity, so we still have some liability, so it is a liability concern to me.”

* Chris Sugidono can be reached at csugidono@mauinews.com.