Reservoir levels continue to fall

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AVERAGE DAILY WATER USE

DistrictOct. 9-15Oct. 2-8Oct. 2007

Central Maui24.97 mgd24.77 mgd25.44 mgd

Upcountry7.89 mgd7.86 mgd7.61 mgd

Lahaina5.27 mgd5.12 mgd6.21 mgd

Hana0.33 mgd0.28 mgd0.30 mgd

Molokai1.18 mgd1.12 mgd1.32 mgd

Total39.64 mgd39.14 mgd40.88 mgd

WAILUKU - Periodic trade showers may have helped to keep demand for water stable over the past week, but consumption on the Upcountry system edged up for the third straight week while storage continued down.

Deputy Water Director Eric Yamashige said overall demand remained below 40 million gallons a day and urged consumers to continue to be careful with their usage.

He noted that Upcountry reservoir levels are continuing to fall from lack of adequate rainfall in the East Maui watershed. An official with Hawaiian Commercial & Sugar Co. said the lack of rain has blocked replanting of about 2,500 acres of sugar fields.

"Water production demand increased slightly in all areas this past week," Yamashige said in the department's weekly water use report. "I am glad to see total production below 40 million gallons a day. I hope we can keep it at this level until we get some rain."

In the Upcountry system, which relies on stream flows for most of the water provided to customers, inadequate rainfall continued to be a concern. Reservoir levels dropped steadily from 94.1 million gallons Oct. 6 to 72.9 million gallons Friday.

The Upcountry reservoirs have a capacity of 180 million gallons. With consumption running at well over 7 mgd, the reservoir levels represent just a 10-day reserve.

From Oct. 7 to Tuesday, flow in the Wailoa Ditch ran below 30 million gallons a day, falling to a low of 21.3 mgd Tuesday. The ditch supplies the county system at the Kamole Weir treatment plant and is also the primary water source for HC&S fields.

The ditch has a capacity of nearly 200 mgd. But it draws on streams flowing out of the East Maui watershed, which has been receiving below-normal rainfall for more than a year.

The condition of the watershed was evident at midweek. When a cloudburst dropped 1.49 inches of rain at the West Wailua Iki rain gauge overnight Tuesday, the rainfall sent flow in the Wailoa Ditch soaring to 132.7 mgd Wednesday. But the increased flow lasted just for a day, with the ditch dropping back to 34.3 mgd Thursday - an indication that the spike was solely from runoff, with much of the water soaked up by dried-out ground of the watershed.

"Reservoir levels are still dropping slowly, even though we have been pumping water up from the Makawao system to the Lower Kula system," Yamashige said. "We need rain, especially at the higher elevations."

Stream diversions that feed into the county's Piiholo, Waikamoi and Kahakapao reservoirs are at higher elevations, between 5,000 and 7,000 feet in the Waikamoi watershed. When the flows into the reservoirs are low, the county pumps water from the Kamole Weir to Piiholo to maintain storage levels.

The East Maui Irrigation Co. ditches divert streams at lower elevations, where there usually is more rainfall. But the low flows in the ditches are not providing sufficient water for the HC&S fields in Central Maui.

With the county drawing as much as 5 mgd at Kamole to provide for domestic consumption, EMI manager Garret Hew said the plantation is unable to replant 2,500 acres that were harvested this summer because of the lack of water.

"HC&S has 2,900 acres open for planting. Due to the low rainfall and ditch flows, 2,500 acres out of the 2,900 acres cannot be planted because they are solely dependent upon surface water for irrigation," he said.

"The spike in ditch flows on Wednesday only provided a small drink to keep the sugar cane alive for next year's crop."

All of Central Maui remains rated in extreme drought, while other areas - including the watersheds - are rated as abnormally dry. The National Climate Prediction Center is forecasting that the islands overall will be seeing below-normal rainfall through the end of 2008.

For the weekend and early in the coming week, the National Weather Service forecasts isolated showers blowing in on the trade winds. But showers will be light, and the trade winds are expected to weaken Monday.

Edwin Tanji can be reached at citydesk@mauinews.com.