Continuing low rainfall across the state prompted the state Commission on Water Resource Management to issue a warning that streamside landowners cannot divert streams without a permit, The Maui News reported.

In a notice issued Wednesday, the commission said it has received reports of streams drying on all of the main islands, along with reports of unpermitted stream diversions.

The notice said the commission can impose fines of up to $5,000 per day for unauthorized diversions.

But commission Deputy Director Ken Kawahara said the primary message was to urge conservation of water by the public. In most areas of the islands, rainfall is less than half of normal, sharply cutting stream flows.

"Water is a precious resource, not only for consumptive uses, but to preserve the life of our native aquatic wildlife, such as the oopu and opae," he said.

"Especially during this period of drought conditions, we strongly encourage water conservation."

The weather service forecast light to moderate trade winds through the rest of the week as a low-pressure front passes north of the islands and weakens the trade winds.

On Wednesday, the trades were moderate to brisk, but an inversion layer allowed daytime temperatures and humidity to rise. In Hilo, the high of 88 degrees tied a record for the day on Wednesday.

On Maui, a high of 90 degrees in West Maui set the pace, although the Kapalua-West Maui weather station reported showers in the vicinity and winds gusting up to 28 mph.

In Kahului, the daytime temperature reached 89 degrees with brisk trades at 25 to 29 mph.

The upper-level ridge was helping to maintain atmospheric stability, the weather service said. While that allowed cloud buildup, the inversion mostly contributed to higher humidity. Around Maui on Wednesday, dewpoint reached 70 degrees, the temperature at which moisture in the air will condense indicating high humidity.

The brisk winds offset the lack of surf for windsurfers, although they did little for other ocean users. A high-surf advisory was issued late Tuesday based on an expectation of an incoming south swell, but was canceled when the waves remained below advisory levels.

The weather service said two cyclonic storms around New Zealand and Tahiti were expected to produce a series of swells through Saturday.

But the swell arriving Wednesday proved to be smaller than forecast at knee- to waist-high along the Maui coastline.

The larger concern was the low rainfall levels. Through the week, rain gauges across Maui County have recorded little rain with the key watershed gauges showing 0.2 inches in East Maui and 0.8 inches in West Maui since Aug. 22.

The effects of the low rainfall was showing in flows in the Wailoa Ditch, which is a primary source for the Upcountry Maui water system. Since Aug. 22, the flow has fallen from 81.4 million gallons a day to 53.7 mgd on Tuesday.

The ditch draws water from streams along the East Maui watershed to supply the county Department of Water Supply and Hawaiian Commercial & Sugar Co.

East Maui Irrigation Co. is permitted to operate its stream diversions as part of the century-old plantation irrigation system. But the water commission emphasized that any new stream alterations or diversions require permits from the commission as well as from county, federal and other state agencies.

Permits will protect existing users when there are competing interests, the commission notice said.

Anyone with questions may call the commission. From Maui, the number is 984-2400, ext. 70234; from Molokai or Lanai, the number is (800) 468-4644, ext. 70234.

The notice said the commission is mandated to consider all stream needs, including recreational, aesthetic and habitat, along with public uses.

"Water is a public trust resource and all residents, businesses, private and public agencies must do their part by not wasting water and being conscious of how much water they are using," Kawahara said.