Water flows near record lows

WAILUKU — While west Molokai slid into severe drought status with the approach of the summer solstice Friday, Maui water users cut down on consumption across the board over the past week.

But Water Director Jeff Eng said the seriousness of the continuing dry conditions is still to be determined, noting that water flows in the Upcountry system are approaching historic lows.

“Summer has officially begun and the potential severity of the drought is yet to be seen,” he said in his weekly water use report.

Even as Upcountry consumers cut use by 770,000 gallons a day, the Department of Water Supply cut back on its use of the Wailoa Ditch when the flows dropped below 16 million gallons a day for three days.

“Wailoa Ditch is the sole source of raw water for the Kamole Water Treatment Facility, Upcountry’s primary potable water source,” Eng said. “Water levels reached a flow of only 15 million gallons a day Thursday and there was a seven-day average flow of 17.4 million gallons a day.

“We have not seen ditch flows as low as this in many years. It is approaching all-time historical low levels.”

After water use climbed over the previous three weeks, demand on county systems fell by 1.2 mgd during the period of June 12-18, according to the department’s weekly report.

Even on Molokai, where the U.S. Drought Monitor showed conditions worsening on the west end, water use was down from 1.57 mgd to 1.5 mgd.

According to the Drought Monitor data, all of the islands have been abnormally dry since March. Central Maui and portions of Upcountry were listed in moderate drought last month, and west Molokai was rated in severe drought as of last week.

The drought index is based on factors such as stream flows and soil moisture. For moderate drought, soil moisture is measured at 11 percent to 20 percent; in severe drought it is from 6 percent to 10 percent. With moderate drought, there is expectation of water shortages; with severe drought, water shortages are occurring.

The Drought Monitor (www.drought.unl.edu/dm/monitor.html) noted that there have been scattered showers across the islands but said the rain missed the drought-stricken areas, and what fell wasn’t enough to alleviate the abnormal dryness.

In the East Maui watershed, the West Wailua Iki rain gauge recorded 1.63 inches of rain over the past week, most of it — 0.99 inch — falling on Thursday and Friday. The trade showers in the watershed helped to restore flows in the Wailoa Ditch. After falling to 15 mgd Thursday, the ditch was up to 31.4 mgd Friday.

But flows into the Upcountry reservoirs were minimal. On the Upper Kula system, the Waikamoi Reservoirs that had been empty picked up about 300,000 gallons Friday, but the 100-million-gallon Kahakapao Reservoir remained below 20 million gallons through the week, falling to 18.6 million gallons Friday.

On the Lower Kula system, the 50-mg Piiholo Reservoir was nearly full Friday at 44.7 million gallons.

The water department has been pumping water to the Lower Kula and Upper Kula systems, seeking to sustain levels in Piiholo. But with the Wailoa Ditch falling so low, the department cut use of the ditch from 5 mgd to 2.8 mgd — only enough to supply the Makawao-Haiku system — and began to draw on Piiholo.

The department has a drought watch on the Upcountry system, asking consumers to cut use by 5 percent.

“Please continue to control your discretionary water use,” Eng said.