March sets records for low rainfall on Maui

Troubling dry trend developing in normally wet period

By EDWIN TANJI City Editor
WAILUKU — March is normally one of the wettest months of the year, but March 2008 set records for low rainfall at five Maui County sites, including Haiku and the Kahului Airport, the National Weather Service reported last week.

The situation over the first three months of the year is not an indicator for the remainder of the year, but an early shortfall on rain will be a problem if it continues, according to weather service senior hydrologist Kevin Kodama.

“It’s kind of early to tell if this type of trend will continue, but if you can’t replenish your watershed before the summer months, that can’t be good,” he said. “If you get to the heart of the warm season, and we’re still looking at low reservoir levels and demand starts to go up, that is a problem.”

The mostly clear skies have Water Director Jeff Eng concerned, with water use climbing steadily through March and into April.

Last summer, the Department of Water Supply issued a drought warning, imposing mandatory restrictions for Upcountry consumers, and a water use advisory for the Central Maui system, urging consumers to cut use by 10 percent.

While the Central Maui advisory — directed at consumers from Wailuku to Paia to South Maui — remains in effect, it is still only a voluntary restriction that sets a target consumption rate of 25 million gallons a day. During the period from March 27 to April 2, demand on the Central Maui system edged up to just over the target at 25.14 mgd.

“We are really monitoring the Central Maui production,” Eng said.

The Upcountry system is also showing stress, although a week of trade wind showers on the watersheds helped to replenish water storage at the end of the week. The Upcountry system is more sensitive to low rainfall because most of the water for the region from Haiku to Ulupalakua is from stream flows in the East Maui watershed.

But the Central Maui system, which draws from the Iao and Waihee aquifers, also is affected by low rainfall when residents increase use to irrigate lawns and landscaping that dry out under clear skies.

“Comparing the production to a year earlier, we are actually hoping we are seeing some conservation effect,” Eng said. “I have to believe there are people out there doing the right thing.”

While demand on the Central Maui system has been rising for the past month, the usage over the past week still was below the average for the month of April 2007 — when the slowdown in rainfall also began early in the year.

Conversely, Eng noted that the average daily demand in March this year was up by 900,000 gallons a day over March 2007.

“While the department realizes that water conservation can be achieved by legislative mandates and penalties, we believe that conservation is best achieved when citizens take personal responsibility to preserve, protect and conserve our precious resources,” he said.

In his monthly rainfall report, Kodama said a dry, stable weather pattern appeared across the islands Feb. 9 with a stationary high-pressure ridge established through March 12. An upper-level trough destabilized the atmosphere around March 17-18, when more than 8 inches of rain fell on Puu Kukui over five days and about 5 inches fell at West Wailua Iki in the East Maui watershed over the same period.

But for all of March, the gauges in the two watersheds recorded rainfall well below normal. With 9.94 inches overall, West Wailua Iki was at 46 percent of normal for March, while Puu Kukui with 13.18 inches was at just 33 percent of normal.

Only one gauge recorded more than 50 percent of normal: Oheo, with 4.8 inches at 58 percent. Four gauges recorded no rainfall: Waikapu, Kihei and two on Kahoolawe.

Kahului Airport with 0.01 inch, Molokai Airport at 0.03, Ulupalakua Ranch at 0.11, Kahakuloa at 0.22 and Haiku at 0.77 were all record lows.

“The new records at Kahului Airport, Ulupalakua Ranch and Molokai Airport were of greater significance since these sites have more than 50 years of record,” Kodama noted.

The dry conditions are affecting the entire state, with all of the islands listed as abnormally dry by the U.S. Drought Monitor (www.drought.unl. edu/dm/monitor.htm) and the March rainfall report showing virtually every area in the islands recording rainfall well below normal for the first quarter of 2008. Lihue is at 41 percent of normal, the Honolulu Airport is at 10 percent, Kaneohe on Windward Oahu is at 15 percent, Lanai City is at 18 percent, Kaunakakai is at 12 percent and Makapulapai at Kalaupapa is at 14 percent. Most of East Hawaii is showing normal rainfall for the year, but West Hawaii gauges are not, with the Keahole Airport at 49 percent and Kamuela at 38 percent.

Kodama said “normal” in March is a lot higher than in other months, with nearly 10 inches in West Wailua Iki and more than 13 inches at Puu Kukui in the West Maui watershed providing a healthy amount of water.

“You can’t just focus on the percentage of normal because your normal is pretty high for the time of year,” he said.

But even if the trades continue steadily into the summer, they would be expected to be drier as the destabilizing winter frontal systems in the North Pacific shut down for the summer. During the summer, the most significant rainfall around Hawaii is generated by tropical storms developing in the eastern Pacific that bring instability from southeast of the islands.

While the water department monitors the increase in water use, Eng said he urges consumers to maintain water use discipline and control their discretionary use.

“We will be looking at options for controlling outdoor watering,” he said. “We want to work with the mayor and the council on what we can do to encourage conservation. Fortunately, they understand what we are trying to accomplish.”

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