Water Use and Conservation

To keep our 36,000 acres of sugarcane healthy and maximize sugar production in the plant, we require, on average, approximately 200 million gallons a day (MGD) of water for irrigation. We know this is a lot of water and we are careful to use it efficiently. HC&S utilizes drip irrigation, which delivers a precise amount of water directly to the root of the cane plants, in all of its fields, except those which utilize recycled water from HC&S’ mill. In fact, HC&S is the largest privately owned drip-irrigated farm in the United States.

HC&S depends on three water systems to meet its water needs. The East Maui Irrigation (EMI) ditch system which collects water from the windward slopes of Haleakala; the West Maui ditch system, co-owned and operated by HC&S and Wailuku Water Co., which collects water from four streams originating from the West Maui mountains; and a system of 15 brackish water wells.

EMI Ditch System


HC&S’ sister company, East Maui Irrigation (EMI), operates a ditch system which collects surface water (rainfall) on the east side of the island and delivers it to HC&S’ fields in Central Maui, as well as to the County Department of Water Supply, which in turn treats and provides the water to Upcountry farmers and residents.

The EMI system was built more than a century ago—an engineering feat that would later shape water reclamation and irrigation procedures used by engineers of major projects on the U.S. mainland. Today, it encompasses 75 miles of ditch, tunnels, siphons, flumes and reservoirs. There are also three hydroelectric plants, producing clean renewable energy, incorporated into the ditch system, utilizing the force of the water as it drops from one ditch to another.


Today, EMI is not only the largest privately built and operated water system in the nation, but it remains one of the world’s most efficient. The ditch system is very efficient in transporting water as the majority of it (50 miles) is lined, thus reducing seepage, and evaporation losses are essentially eliminated in the 50 miles of enclosed tunnel due to the lack of exposure to sunlight and wind. EMI conducts a regular program of inspection and repair/maintenance. Thus, the physical features of the ditch system as well as EMI’s management practices serve to minimize the losses of water from the system.

Furthermore, there are no motors involved in moving the water through the system so no consumption of fossil fuels. A sophisticated remote telemetry system transmits data on ditch flows to EMI’s station every eight minutes. This enables water flow to be adjusted at collection points so that only the water that is needed is transported to HC&S’ ditches and reservoirs.

West Maui Ditch System

The West Maui ditch system collects water from the Iao, Waihee, Waiehu and Waikapu streams. It is co-owned and operated by HC&S and Wailuku Agribusiness, originally serving Wailuku Sugar’s and HC&S’s sugar fields in Central Maui. With the closure of Wailuku Sugar, much of that water is now used by HC&S to improve yields on its fields and to serve additional fields HC&S has leased for cultivation. The West Maui ditch system also serves the needs of other farmers, businesses, residents and kuleana lands.

Brackish Water Wells

HC&S utilizes a battery of 15 brackish water wells to supplement its ditch systems, when insufficient surface water is available. These wells are of limited use for a number of reasons. First, this well water cannot reach all of HC&S’ fields—there are 12,800 acres on the slopes of Haleakala that are completely dependent on EMI ditch water for irrigation. Secondly, brackish water is not as good for the cane plant and fresh water—the salt content not only reduces growth but will accumulate in place of sugar in the plant. Lastly, the cost of well water is considerably more than ditch water and it is important to HC&S’ viability to manage costs while increasing productivity.

Water Re-Use

  • All of the water used at the mill, to wash and process the cane, is recycled, filtered (to remove dirt) and re-used in our fields.
  • Water collected by the EMI ditch system is used to generate power, then in the fields for irrigation.
  • HC&S’s irrigated fields serve as ‘sponges’ to replenish Maui’s aquifers. Any water not directly consumed by the plant seeps into the ground, feeding Maui’s aquifers. Without the irrigated fields, aquifer yields are likely to decline. This is what happened on Oahu—when sugar cultivation ceased, the sustainable yield of the Pearl Harbor aquifer declined.