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Soil and Water Conservation District



Waimea-Paauilo Watershed Project

The Waimea-Paauilo watershed is approximately 143,900 acres and is located in the northeast part of the Island of Hawaii. The area is bounded by Highway 19 to the north and the town of Paauilo to the east. The project extends to the 8,000 foot level of Mauna Kea in the south and to the Waikoloa Stream drainage in the west. Current land use consists of irrigated cropland, pastureland, forest reserve and watershed and urban area. The climate of the project area is characterized by moderate variations in annual temperature, and significant variations in average annual rainfall. The average annual temperature varies from 75 degrees F at the coastline to 40 degrees F on the upper slopes of Mauna Kea. The average rainfall varies from over 175 inches in the Kohala Mountains to 20 inches south of Waimea. This variation occurs in a distance of about 4 miles. Rainfall is not uniform throughout the year. There are dry periods that last from 30 to 90 days or more.

Most surface water in the project area originates on the higher slopes of the Kohala Mountain. Streams are perennial at their headwaters. Most of the flow in these streams is either diverted into lined ditches, tunnels, pipelines, and reservoirs or disappears into faults or lava tubes before reaching the coast. The major problem of the watershed is an inadequate water supply due to insufficient agricultural water storage reservoirs and a water collection system with high seepage losses. The distribution systems are inadequate for the agricultural enterprises in the watershed area. If implemented the project would improve agricultural water management through more efficient irrigation and livestock water distribution systems, will protect the soil resource base by facilitating better pasture management and improve the production of crops that are in deficit supply within the State of Hawaii.

Click here to download the Waimea Paauilo Watershed Plan and Environmental Impact Statement.