Waiahole Ditch | Images of Old Hawaiʻi

In 1897, the Oʻahu Sugar Company established a large-scale sugar plantation on the dry, southwestern side of Oʻahu. Irrigation water for the sugar-cane plantation was initially pumped from the Pearl Harbor aquifer.

Because of the high pumping cost, the Oahu Sugar Company constructed the Waiāhole Ditch System to transport, by gravity, surface water from the northeastern side of the Koʻolau Range. The Waiāhole Ditch collection and delivery system was initially constructed during 1913-1916.

The system intercepts large amounts of dike-impounded ground water at high altitudes (above approximately 700 to 800-ft) that previously discharged to Waiāhole (and its tributaries Waianu and Uwao), Waikāne and Kahana Streams through seeps and springs.

The main tunnel through the Koʻolau Range was primarily designed as a transmission tunnel. The success of this tunnel in intercepting large amounts of dike-impounded ground water in the Koʻolau Range led to the construction of additional high-level ground-water development tunnels.

Between 1925 and 1935, six tunnels with headings directed into the Koʻolau Range were added to the ditch system to develop ground water stored in dike compartments. Four development tunnels (Uwao, Waikāne 1, Waikāne 2 and Kahana) were considered successful.

For nearly a century, the Waiāhole Ditch System has diverted an average of approximately 27-million gallons per day of water from the wet, northeastern part of windward Oʻahu, to the dry, central part of the island to meet irrigation needs.

This diverted flow consists of ground water gained from the connecting tunnels, the four development tunnels, and the trans-Koʻolau tunnel and of surface water gained primarily from Kahana Valley.

The flow diversion through the tunnel is pretty low tech; a redwood board determines the flow direction and amount. Depending on which marker the board is raised or lowered to, more or less water flows to leeward or windward areas.

If the board is raised, more water flows to the leeward side. Conversely, the more the board is lowered, the greater the amount of water that flows to Waiāhole stream.

The Waiāhole Ditch collection and delivery system is a 26.5-mile-long system, also called “the ditch,” extending from Kahana Valley on the Windward side to the Kunia area on the Leeward side.

The effects of Waiāhole Ditch diversions received significant attention in 1993, when it became known that large amounts of diverted water were not being used for irrigation and instead were being released into streams on the leeward side of Oʻahu. This coincided with the Oʻahu Sugar Company announcement of the closure of its sugar-plantation operations.

Windward stream water for leeward uses initiated a legal proceeding (Waiāhole Ditch Contested Case) before the Hawaiʻi Commission on Water Resource Management (CWRM) over rights to the water.

The Waiāhole case arose from the efforts of small family farmers and Native Hawaiians, led by citizen groups Hakipuʻu ʻOhana, Ka Lahui Hawaiʻi, Kahaluʻu Neighborhood Board, Makawai Stream Restoration Alliance and a coalition of supporters (collectively the “Windward Parties”), to restore streams originally diverted by Central O`ahu sugar plantations.

But large scale agricultural and development interests, including Campbell Estate, Robinson Estate, Kamehameha Schools, Dole/Castle & Cooke, and others, joined by the State, pushed to continue the flow of Windward water to leeward lands to subsidize golf course irrigation, short-term corporate agriculture, and housing development.

After seven months of administrative hearings, the Water Commission issued its first decision in 1997, which both the Windward and Leeward parties appealed to the Hawaiʻi Supreme Court.

The Windward Parties argued that not enough water had been restored to the streams, while Leeward interests complained that too much water had been returned.

In August 2000, the Hawaiʻi Supreme Court issued a landmark decision in the first appeal. Although the Court acknowledged the Commission’s efforts at stream restoration, it vacated the Commission’s decision and sent the case back to the Commission.

After holding more hearings, the Commission issued a second decision in December 2001, which the Windward Parties again appealed.

The Court ruled that much of the decision failed to comply with the State Water Code and public trust principles, and the Commission had failed to make sufficient findings, based on evidence in the record, to support its various rulings.

It ordered the Commission to reconsider the amount of water the Windward streams need to support native stream life and community uses, vacated permits the Commission had issued to Leeward interests, and ordered the Commission to make a new decision on the permits that followed from the evidence.

On July 14, 2006, the Hawaiʻi State Commission on Water Resource Management issued a split decision in the landmark water rights litigation over the stream flows diverted by the Waiāhole Ditch System on O`ahu.

Four members of the Commission (a majority) voted to largely maintain the allocations the Commission approved in its original 1997 decision, including extensive diversions for Leeward uses, such as corporate agriculture and golf courses.

However, two Commissioners issued a dissent criticizing the majority for failing to give more protection to Windward stream resources and uses.

As Water Commission Chair, I was happy to have authored the dissent (with significant assistance from the Attorney General’s office) and pleased that Chiyome Fukino, state Department of Health Director, joined me in the dissent.

In 2010, the Intermediate Court of appeals vacated the water use permit issued in the 2006 decision and remanded the case back to the Water Commission. (Lots of information here from USGS and EarthJustice reporting on the ditch system and Waiāhole Ditch case.)

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Byron Alcos, superintendent of the Waiahole Irrigation Co., shines a light pon the source of the Waiahole water-(star-bulletin)

Monument at the Waiahole Ditch announces the completion date and names of contractor Mizuno, his surveyor, stonemason, and workers-(hawaii-gov)

Waterfall at one of the water sources of Waiāhole Stream, windward O‘ahu, Hawai‘i-(USGS)

Waikane_Valley-Loi_Kalo-Bishop_Museum-photo-1940

Waiahole Ditch-Land-use and land cover-(USGS)

Waiahole Ditch-generalized geology-(USGS)

Oʻahu Sugar Company constructed the Waiāhole Ditch System to transport, by gravity, water from the northeastern side of the Koʻolau Range. The Waiāhole Ditch collection and delivery system was constructed during 1913-1916.

The general plan or scheme of development adopted for the Waiāhole Water Co. was that recommended by Mr. J. B. Lippincott, C. E., who made an exhaustive study of the project, going fully into the past history and study already made by Mr. J. Jorgensen and other parties, and reported to the Board of Directors of the Oahu Sugar Co., Ltd., under date of August 19, 1911.

The general plan provided for collecting the water from the many streams and gulches on the windward side of Oahu by means of tunnels through the ridges or spurs, and conveying the water, after collecting, through the mountain in the main tunnel to the leeward side of the island, thence by tunnels, ditches and pipes, to the upper levels of Oahu Sugar Plantation.

The tunnels connect up the various streams on the North side, and take in the water at the adits in the gulches. There are 27 of these tunnels on the North side, varying in length from 280 feet to 2,332 feet, the aggregate length of the North side tunnels being 24,621 feet, or 4.66 miles, being in reality one continuous tunnel.

The maximum elevation at which water is taken into the tunnel is 790 feet above sea level, and the grade or slope of the North side tunnels is 1.3 feet per thousand. The length of the main tunnel through the Koʻolau Ridge is 14,567 feet, or 2.76 miles, the grade or slope being 2.0 feet per thousand.

The elevation of the North portal of the main tunnel is 752 feet above sea level, and at the South portal 724 feet. The size of tunnel section is approximately 7 feet wide and 7 feet high, but in many places the section is larger, due to the uneven cleavage of the rock, and the fact that certain portions are unlined.

From the tunnel, the water is then conveyed by means of cement-lined open ditches, elevated concrete ditches, four steel pipes, and three redwood pipes. It is delivered to the upper boundary of Oahu plantation at an elevation of 650 feet through several distributaries, and by the main ditch, which reaches this elevation at the boundary of Honouliuli.

The water is also delivered into numerous reservoirs, especially at night, when irrigating the cane fields is inconvenient. One of the larger reservoirs, on the line of the Waikakalaua storm water ditch, has long been in use. It is called Five Finger Reservoir. Its elevation was a determining factor in establishing the grade elevation of the Waiāhole conduit.

When the work was undertaken, the time of completion was considered an important element, and Mr. Bishop’s organization was planned to secure the most expeditious execution of the project. The General Superintendent of Construction, Mr. Albert Andrew Wilson, who was in direct charge of all the constructing work.

At the beginning of the tunnel work, three shifts of eight hours each were kept going. This was continued until the large amount of water coming into the tunnel, at North heading, became troublesome, and on account of the hardship on the men, working for eight hours in the cold water, it became necessary to cut the shifts down to six hours each, so that four shifts per day were employed for this heading.

The temperature of the water in the tunnel was approximately 66° F., or about 8° colder than the artesian water in Honolulu, or, roughly, about 1° for each 100 feet of elevation.

Camps were established and sanitary conveniences were built to comply with the requirements of the Board of Health. No serious sickness, such as typhoid fever, gave any trouble.

Special tribute should be paid to the Japanese tunnel men, without whom the excellent progress made on the tunnel would have been impossible.

These “professional” tunnel men, as they call themselves, prefer this work to any other, and they apparently take delight in the hardships incident to the work, the exposure to the cold water, and the risk in handling explosives.

They were on the job all the time and never failed to deliver the goods in situations in which white men or native Hawaiians would have been physically impossible. Most of the drilling and mucking was done by these tunnel men as subcontractors – a bonus being given for rapid work, which sharpened their interest and never failed to give results.

While it was suspected at the outset that considerable water might be encountered in the main bore through the mountain, it was not anticipated at the beginning that enough water would be developed to materially interfere with the progress of the excavation.

This hope was not realized, however, for the main bore had proceeded only about 200 feet from the North portal when water to the extent of two million gallons daily was developed—this on breaking through the first dyke.

These dykes are hard, impervious strata of rock lying approximately at an angle of 45° to the tunnel axis, and nearly vertical, and they occur at intervals of varying length. Between the dykes was the porous water-bearing rock, thoroughly saturated, and with the water pent up between the dykes often under considerable pressure.

When a dyke was penetrated, the water would spout out from the drill holes and would gush forth from the openings blasted in the headings. As the work progressed, the water increased in quantity and the difficulty of the work was enormously greater on account of the water.

The texture and hardness of the rock varied considerably— some of it being particularly soft and porous and much of it hard and flinty—particularly at the dykes. The dykes varied in thickness from 14 feet down to about 4 feet, all composed of very hard, close-grained rock which was apparently waterproof.

From the South portal the progress was rapid, often as high as 630 feet per month, or about 21 feet per day on an average, notwithstanding the long haul, which at the last was over two miles.

Eighty-percent of the length of the main tunnel was driven from the South portal, and 20% of the length was driven from the North portal, the difference in these proportions from the two headings being due to the presence of water at a much earlier stage in the North heading. Had there been no water to contend with, the length driven from each heading would have been approximately the same.

This system of tunnels is essentially a closed-conduit system, that is, the flow is entirely through closed tunnels, not subject to interruption by freshets or washouts or from rubbish or wash from the mountain streams, the intakes being so built as to admit only water as free from rubbish as practicable.

Only at three points in the tunnel system—and these are on the South side, one of which is a gaging station—does the water flow in open channels for an aggregate length of 160 feet.

It is intended to use the reservoirs so far as possible to take care of the water flowing at night, so as to utilize the conduit to its fullest capacity.

The Waiāhole Water Co. has taken over from the Oahu Sugar Co. The water delivered by the Waiāhole System is chiefly used on newly planted cane on land above the lift of the pumps. During construction the water developed in the main tunnel near the South portal was at times utilized for irrigation.

On May 27, 1916, with Mr. H. Olstad as Superintendent, continuous operation of the project was begun. (This post is from portions of a paper read by Chas H Kluegel before the Hawaiian Engineering Association, published in Thrum, 1916)

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