The Water Tunnels of Ka’u Old Plantation Days January 2013

Many of the articles of “Old Plantation Days” in the Paradise Post have been centered on water and plantation water development. This months’ issue will cover one of the most interesting and fascinating developments of water by plantation engineers of the early 1920’s in the district of Ka’u.

The plantations of Hutchinson Sugar and Hawaiian Agricultural had a combined acreage of around 15,000 acres in cane. Cane needed water to grow, to transport it down the country side, and then it was needed for process water in the mill. How did that occur in a district that has NO (none, a’ole, nada, nine), perennial flowing rivers to tap into? The Ka’u district plantations developed one of the most unique methods of extracting water from the rocky lava flow slopes of Mauna Loa…they bored into the side of the mountain and tapped into trapped high elevation ground water. These tunnels were called Horizontal Shaft Ash Bed Tunnels. Just as the name implies the tunnels went horizontally into the mountain and they were dug at the region where a bed of dense “Pahala Ash” was covered by an ancient lava flow from the summit of Mauna Loa.

The hanawai men of the plantation had the help of the USGS when boring these tunnels. Several engineers were recruited by the plantation to assist in locating these hidden underground sources of water. One headline of the newspaper states “Water Witches arrive from Mainland!” The engineers and plantation staff would search the hillsides for wet areas with seeps or known spring sites. These were where an ash bed heavily compacted over eons of time and covered by subsequent lava flows were intercepting rainwater seeping down from the surface. The water upon reaching the dense ash layer tended to travel horizontally trying to find its way out or through the ash on its long and eventual path to the ground water of the island many thousands of feet below.

Once the ash bed was found and the tunnel driven into the slope, the water found a “release” from its captive high elevation head. The tunnels were often bored many thousands of feet long into the mountain. “Mountain House” tunnel above Naalehu was over 7,000 feet long. This tunnel continues tosupply domestic water to the current residents of Naalehu, Waiohinu, and South Point. “Noguchi Tunnel” above Wood Valley Homesteads is over 3,000 feet long and still to this day supplies domestic as well agricultural water to the macadamia orchards and coffee orchards below.

There are some 38 known tunnels within the district, yet only a handful are still currently working and supplying water. Most of the systems were abandoned in the late 1940’s after World War II. That was when deep well shafts were drilled near the mills and water was pumped from the ground water lens below. The high maintenance of the tunnels and wooden flume trestle systems were abandoned for cheap oil and electric powered pumps. Fast forward to the present….the plantation mills are gone, so are their pumps, so is cheap oil, so is cheap electricity. Ka’u was in desperate need of good inexpensive agricultural water but we had no way to get it from the deep wells that were now themselves abandoned and far too expensive to even consider renovating for agriculture. The free flowing gravity driven systems of the tunnels still existed way up in there in the mountains above and just a few ‘old timers’ knew where they were.

Current landowners, coffee growers, macadamia companies, ranching operators, and Native Hawaiian Homesteaders have recently formed the “Ka’u Agricultural Water Cooperative District”. This entity has been formed to work amongst themselves as a water cooperative and also with the Department of Land and Natural Resources, the State Department of Agriculture, the Agribusiness Development Corporation, and the County Department of Water Supply. This cooperative has been tasked to renovate some of the old tunnels and transportation systems to once again bring precious water down to the thirsty agricultural fields below.

One of the tunnels that has been recently renovated by the Ka’u Coffee Mill, LLC and the Edmund C. Olson Trust II as part of the KAWCD is “Clark Tunnel”. This tunnel was named after W.O. Clark, one of the original water witches from the USGS to come to Ka’u. This tunnel when re-discovered some three years ago was completely blocked at the portal. Once the portal was cleared of about 150’ of debris and boulders the tunnel once again started flowing. The photograph accompanying this month’s issueshows the beautiful mountain forest of Ka’u and the renovated Clark tunnel that now supplies about 250,000 gallons a day to the fields below.

These water systems will support the expansion of agricultural opportunities as clean hydro-electric power for Ka’u!