KOLOA, Kaua'i — The Waikomo Stream, normally a year-round free-flowing stream, for roughly two months has been completely dry a half-mile up from the ocean.

"I can't remember the stream ever being dry before," said Ted Blake, a lifelong resident of the region.

Nobody clearly knows why, other than there has been very little rain. But residents have many notions, including extensive blasting in recent months by developers, pumping of wells near the stream, multiple diversions from the stream for irrigation, and significant changes in water management in the region with the loss of sugar and the abandonment of reservoirs because of dam safety concerns.

Waikomo is now just a trickle as it crosses the Kiahuna Golf Course. It no longer flows at all past the county's Po'ipu Fire Station. It is dry as the rocky stream bed passes under the new Ho'onani Road Bridge. And no fresh water flows into a small rocky bay at Koloa Landing, where whaling ships once refilled their water casks.

The state Commission on Water Resources Management has investigated, but has no clear answers, said Ken Kawahara, the commission's deputy director.

"We've been watching Waikomo for a while," Kawahara said. "We are watching it very closely, and we are very concerned. We see the ecological value, and we believe the stream should continue to the ocean."

Clearly a significant issue — and in Kawahara's mind it is the the main issue — is dry weather. In another part of the island, the flow of water on the north fork of the Wailua River is at 48 percent of its median flow for May through July — and that is the lowest flow ever recorded for that period, he said.

"We've had people walk the river and look at diversions. All of the diversions we found are registered," he said. Furthermore, several of the pipes that took water from the stream no longer do so, because the water is so low that the intakes are above the current water level, he said.

Koloa resident Kaulana Sullivan said the river was running fine during the dry weather earlier this year, before numerous developers on the rocky Koloa plain began preparing land for new homes and resort complexes — and began a persistent program of blasting the rock.

"As soon as the blasting started, the water disappeared. I thought maybe the blasting caused cracks in the stream bed," she said.

Kawahara said his investigators found no signs of that.

The Advertiser walked the stream bed, and found no sudden disappearance of the stream. Instead, the flow diminishes gradually until it trickles into one final pond about a half-mile above Koloa Landing, and then flows no more. The final pond is alongside Po'ipu Road, a few dozen yards above Kukui'ula Store.

There are several wells in the region, including four registered to the Kiahuna Golf Course. Kawahara said there has not been a thorough hydrology study done to indicate whether heavily pumping wells could lower the water table and reduce stream flow. He said some water users in the area are using recycled wastewater to augment other water sources.

"We're also looking at the changing irrigation practices in the area," Kawahara said.

The watershed that once fed Waikomo Stream was significantly altered during the sugar era, with ditches and siphons moving water back and forth to fill reservoirs, which in turn were used to irrigate cane fields and assist in processing sugar cane at the Koloa Mill. Some of those irrigation systems have been diverted to other crops. Some are not being used at all. And at least two area reservoirs have been drained and stand empty, because of concerns after Kaloko Dam's failure last year that they were at risk of failure.

It's not clear whether the abandonment of reservoirs diverted incoming flows into new streambeds, and may have reduced the flow into Waikomo, Kawahara said.

But his sense, he said, is that Waikomo Stream's problem is associated with unusually dry conditions statewide on Kaua'i and statewide.

"It's not only Kaua'i. We're getting more complaints of dry streams, especially on the Big Island, where there is a drought. Waimea is very dry. There, two of three reservoirs are down because of earthquake damage, and some irrigation ditches collapsed," he said.

The leeward sides of most of the Hawaiian Islands have received just half of normal rainfall during the first six months of the year. The statewide situation has been so severe that Gov. Linda Lingle requested and received a federal drought declaration, which makes low-interest agricultural loans available.

The recent passage of Hurricane Flossie provided a little rain to the windward side of the Big Island, but didn't help in the driest areas, said Jim Weyman, meteorologist in charge at the National Weather Service forecast office in Honolulu.

"It really is dry, and we won't really get any rain now on the leeward sides until we get our rainy season back in October or November," he said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.