State needs steady rain to fill aquifers

By Kevin Dayton
Advertiser Big Island Bureau

HILO, Hawai'i — The recent rain helped ease dry conditions in some parts of the state, but county water officials say the relief is only temporary.

County water managers say they are still hoping for lighter, more steady rainfall to recharge state aquifers, rather than storms like last month's deluge.

The storm late last month helped fill reservoirs in Upcountry Maui and reduce demand by water consumers across the state, but much of the rain ended up as runoff that flowed into the ocean instead of percolating down into island aquifers.

"We've been lucky in that we've had a lot of rain, but it's actually not the kind of rain that we're looking for," said Wanda Yamane, spokeswoman for the Honolulu Board of Water Supply.

If a storm dumps inches of rain on ground that is saturated, "it runs off rather than being able to recharge the ground water system," she said. "Most of that goes down the drainage lines and the ditches and such."

Overall, the state has had relatively dry conditions since 1997, with leeward areas affected the most, said National Weather Service hydrologist Kevin Kodama.

Clifford Jamile, manager and chief engineer of the Honolulu Board of Water Supply, announced early last month that O'ahu's aquifers were 6 inches lower than they were a year earlier.

Jamile warned that the aquifers would need to rise at least 2 feet to recover, and said mandatory restrictions might be necessary this summer.

Last month also was relatively dry until Feb. 26, when a strong winter storm eventually dumped 7 inches to 11 inches of rain in some areas, and caused flash flooding on O'ahu.

Rain gauges on O'ahu in February registered double or triple the normal rainfall for that month, while the 16.35 inches of rainfall recorded at Honolulu's airport for the first two months of the year is almost quadruple the normal amount, according to the Weather Service.

Yamane said there are signs that O'ahu's water sources are recovering, but they are not back to normal.

"With real concentrated conservation efforts by consumers and with additional rains to help to recharge, certainly those two things together would allow the water resource to recover to better levels," she said.

The February storm left the three Upcountry Maui reservoirs nearly full, and has dramatically reduced homeowners' use of water to upkeep their lawns, said Jacky Takakura, administrative officer for the Maui Department of Water Supply.

Kula resident Dan White, who lives at the 3,000-foot elevation, said his yard is looking "very lush" after receiving plenty of rain the past two months.

"Last spring I was able to mow about once every three weeks and get away with it, and now I'm doing it once every two weeks," said White, an educational consultant who works with private schools. "I should be mowing every week. But you know, I love grass, but I'm not going to do it that much."

On the Big Island, the recent rains brought some temporary relief to the county Board of Water Supply by replenishing mountain springs that provide water to communities such as Na'alehu, Wai'ohinu and Pahala.

"We rely on that heavily, so when rains come it really helps that, so we can kind of relax a little bit," said Milton Pavao, manager of the department. The county has wells in Na'alehu and Pahala that can be used when the springs are dry, but those sources are more expensive to operate, he said.

"It's temporary," Pavao said of the reprieve. "If it gets dry again it goes down. It's really, really dependent on the rainfall."

At Sea Mountain Golf Course in Ka'u on the Big Island, course manager Rodney Andres said it hasn't been necessary to irrigate for a week. Andres said that's unusual in Ka'u, where pumping is usually necessary every day to water the course.

The National Weather Service rates the weather in Ka'u for the past two years as "extremely dry," with the area struggling with some of the worst drought conditions in the state.

But the recent rains have made the course so lush that "we cannot keep up right now with the mowing," Andres said.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com or (808) 935-3916.