Water will be pumped up from Piiholo to serve customers.

Storage in the two 50-million-gallon Kahakapao reservoirs was about 12.5 mg Monday, according to Deputy Director Eric Yamashige.

That was the lowest it has ever been in July. The previous record low was 20 mg in July 1999. The all-time low was zero gallons last September.

"It's pretty bad," said Yamashige of the current dry spell.

There was light rain over the weekend at lower elevations. That pushed consumption in the entire Upcountry system down from 9.2 mg on Friday to 8.0 mg on Saturday and 6.4 mg on Sunday.

The 50-million-gallon Piiholo reservoir held 39 mg Monday. The Wailoa Ditch was flowing at 103 mgd, significantly below its capacity of 199 mgd. There is no storage at Kamole Weir, which the ditch flows into.

That meant that the total of stored water was a little more than 50 mg – about 10 days' worth.

Paul Seitz, chief of the department's Water Treatment Division, said Monday that he had shut down one of the Kahakapao reservoirs because the water level was below the intakes feeding the Olinda plant.

The other reservoir "is fading fast," he said.

The Olinda plant can produce up to 2 mg a day when it has enough water. The 35-mg Waikamoi reservoirs have been dry for weeks.

Since June 25, the department has been pumping water uphill in order to extend the supply at the highest level of the system.

The island's dry season doesn't end until around Thanksgiving, which may mean months more of the same for Upcountry residents living under mandatory 10 percent water cutbacks.

Production at Olinda will be reduced to 100,000 gallons per day, which is approximately the consumption just in Olinda.

The Piiholo and Kamole Weir plants treat water with chlorine alone. The Olinda plant uses chloramines for disinfection. As a result, some people may be able to taste the difference in the water. However, that should not be evident before Friday, Yamashige said.

In 2004-06, normally dry weather did not cause much disruption because the water department had the wells at Hamakuapoko to fall back on. Late last year, the County Council prohibited use of those wells.

That throws Upcountry on the mercy of surface water flows, except for a small well in Haiku and a new, larger well at Pookela.

Those two wells provide, at best, around 1.7 mgd. That leaves most of Upcountry's water coming from Wailoa Ditch. The flow there has been as low as 25 mgd this year, although it fluctuates widely.

The Kamole Weir treatment plant can process less than 7 mgd. That means that on any day when consumption rises much more than 9 mgd, the system has to draw on its limited stored reserves.

Harry Eagar can be reached at heagar@mauinews.com.