Waikolu Valley is on the North Shore of Molokai in Hawaii. Access to this uninhabited valley is restricted as it is a part of the Kalaupapa National Park. Hawaiians lived along the North Shore of Molokai including Waikolu Valley, cultivating taro and other food crops. These valleys were visited in the summer months when the area is sunny and accessible by outrigger canoes. In the winter months, large surf pounds this coastline and makes it difficult to ingress and egress by sea.
Waikolu Valley was where the first lepers, that were banned to Kalawao peninsula (Kalaupapa), were off loaded in 1866 to live their lives in isolation. Kalawao is a dry area and water for the growing settlement was obtained from Waialeia Valley, one mile from the settlement. Water had to be carried from a spring in this valley. In the late 30’s military jeeps were used to bring the water down to the settlement.
In the late 30’s, the limited water from Waialeia was insufficient for the growing needs of the settlement. A water development project was undertaken to provide a sufficient supply of fresh water from Waikolu stream.
An intake system was installed at the 520 foot elevation, 1.4 miles up the valley, with a catchment system in the upper Waikolu Valley. The water was piped in galvanized 8” and 6” pipe from the intake, crossing the stream several times and emerging at the shoreline where it was buried where possible and then ran above ground on concrete posts along the base of the high cliffs separating Waikolu from Kalawao. The pipeline had sufficient head to push the water up to Kalawao peninsula where the settlement was located. Remnants of this early water system are still evident today with concrete monuments along the shoreline, remnants of the pipeline and the intake and crossing points on the stream for the pipeline.
This system was difficult to maintain especially in the winter months when the shoreline is pounded with winter swells and storms often would damage or clog the intake. Maintenance crews would hike up to a point near the intake and camp in a maintenance shack to do repairs to the system. This system was replaced in 1982 with a well which gets water from an underground aquifer.
The modern water development from Waikolu Valley started with a federally funded project to divert water from Waikolu Stream to supply water to the dry western part of Molokai to help create jobs in construction and agriculture.
In the late 1960’s, a contract was awarded to construct the Waikolu diversion and development tunnel which diverts water from Waikolu Stream into a 5 mile tunnel that delivers water above Kaunakakai town. This water flows into the 100 million? gallon reservoir in Kualapuu and supplies domestic and agricultural water to Molokai farmers and residents. Two-thirds of the water is for the Hawaiian Homes lands of Molokai and one-third of the water is for other agricultural users and domestic users on Molokai.
The project took 5 years to complete. You can see 4 miles through the tunnel. It has a 4” elevation change to move the water through the tunnel. Cars can travel through the tunnel for maintenance work.
In the tunnel a well was drilled to add water to the tunnel. There are 6 springs that enter the tunnel from the side walls in the tunnel. When the well in the tunnel is turned on, it reduces the inflow from the springs and therefore it is rarely used.
Intake one was constructed to divert water from the main Waikolu Stream, and intake two from a side tributary both gravity feeding into the tunnel. A third intake is located about a mile below the tunnel and an intake and pumping system adds lower elevation water captured behind a dam and pumps the water up to the tunnel. The pumping is on demand. When there is sufficient water in the catchment area the pump automatically turns on until the level is at a designated level and then turns off. These pumps are run by electricity that is brought in through the tunnel. A series of 22 transformers are needed to get sufficient power to the pumps.
There are several environmental improvements including a fish ladder in the intake #1 and a water replacement pipe that allows some of the water from the lower elevation intake to flow back into the stream.
The tunnel is approximately 12’ round with a concrete floor that slopes. The tunnel has a drop of 4” over 5 miles. This water system generates approximately 2 to 5 million gallons of water per day.