Friday | October 20, 2017
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Southside flow

PAHALA — Water trapped between layers of volcanic ash, replenished as towering koa trees filter the mists of the rain forest high above the parched Ka‘u Desert, will soon be powering homes as well as irrigating crops as it rushes through pipelines that have replaced 1950s era plantation flumes.

Some 30 hikers last week were the first to participate in an ecotour where they trekked one and a half miles up the flank of Mauna Loa to the 3,500-foot elevation, taking in the history of plantation flumes that sustained generations of Ka‘u farmers and learning about a five-year, $2 million project that is bringing the technology into the 21st century.

“This is the first time we’re sharing it with the public,” said John Cross, land manager for landowner Edmund C. Olson Trust.

It probably won’t be the last. More than 60 people signed up for a hike that had to be limited to 30. Hikers were occasionally breathless during a walk that gained 400 feet in elevation over the course of the route, but the group, ranging in age from 25 to 75 and wearing a range of gear from hiking boots to what were once white tennis shoes, were unanimous in their enjoyment.

The hike was part of the Ka‘u Coffee Festival, an annual event that culminates today with a day of music, hula, coffee tasting, educational displays and demonstrations and vendors at the Pahala Community Center.

Men and women joining in on the three-hour “technical hike” navigated rocky trails and walked one-by-one on old flumes repurposed as bridges over deep gulches before arriving at a grassy helicopter landing pad where they munched sandwiches as endemic elepaio, apapane and iiwi twittered in the surrounding treetops.

In addition to massive koa and ohia trees, tree ferns and rare plants form leafy undergrowth, with an occasional sugarcane poking through at the lower elevations.

The water project taps into what was once Piikea B Flume, which in turn draws water from tunnel systems burrowed long ago to free the water from the volcanic mud layers.

There are more than 30 such tunnels along Mauna Loa’s flank between Wood Valley and Naalehu. The earliest ones, known as “Chinese tunnels,” were dug in the 1880s. Later came the USGS tunnels, blasted with dynamite to dimensions of 4-foot-wide by 6-to-8-feet tall.

“The Ka‘u tunnel systems are an engineering feat of the 1920s,” Cross said.

In the flume’s heyday in 1947, some 6.5 million gallons of water a day rushed down the mountainside. Nowadays, it’s more like 1.5 million, he said.

Cross points out water surging through a portion of the old flume that’s been left open.

“That’s a piece of history,” he said. “We need to keep what was once here on the mountain.”

In addition to constructing a pipeline to irrigate the 150-plus acres of coffee farm that goes into Ka‘u Coffee Mill’s award-winning coffee roasts, the company just last week received its first installment of machinery to create hydroelectric power from the rushing water. Cross said the company is in talks with Hawaii Electric Light Co. for a power purchase agreement.

As well as powering the Ka’u Coffee Mill farm and operation, the electricity could power as many as 400 Pahala homes.

The Edmund C. Olson Trust is also working with The Nature Conservancy to rid the private property of the invasive kahili ginger, which was once used to mark trails.

“We’ve found trails abandoned for 50 years just by following the kahili ginger,” Cross said. “They used them like breadcrumbs to mark their trails.”

TNC Hawaii Island Director Shalan Crysdale praised the trust for working with his group, which manages the adjacent 61,641-acre Ka‘u Forest Reserve, part of the largest and most intact piece of native forest in the state. The environmental group wants to ensure the ginger doesn’t creep over the property lines and has adopted a minimally harmful, yet tedious, method of killing the ginger by breaking it in half and using a dropper to instill a small amount of poison into each plant.

“It’s unusual for private landowners to work so closely to rid their land of invasive species,” said Crysdale.