CINDY ELLEN RUSSELL / CRUSSELL@STARBULLETIN.COM Glenn Higashi, an aquatic biologist for the Aquatic Resources Division of the state Department of Land and Natural Resources, swam in a stream at the Waiahole watershed in May. Higashi immersed himself in the water as part of a demonstration showing how aquatic biologists count and identify various crustaceans and fish in the watershed.

Waiahole water fallout

Scientists look for the effects of
shifting water from Windward streams

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By Diana Leone
dleone@starbulletin.com

As part of the state Supreme Court ruling in the Waiahole Ditch lawsuit, some of the water that used to flow through the ditch to Leeward sugar fields has been restored to Windward streams.

Whether enough water has been returned remains a point of contention.

"The animals (native fish and invertebrates) need a certain amount of water -- what is it?" asks Robert Nishimoto, Department of Land & Natural Resources aquatic biologist, part of a team of scientists gathering information in an attempt to answer that question.

Beginning today, Leeward users of Waiahole Ditch water will join the U.S. Geological Survey, the DLNR and the state Water Commission in funding such studies. Leeward users will contribute a total of $45,798 annually toward $104,000 worth of studies per year over the next four years, according to the Water Commission.

The Water Commission's ruling on the Waiahole case is on appeal to the state Supreme Court.

To study what's "normal" for Hawaii's streams, researchers needed an island frame of reference, Nishimoto says. They have that in a model recently designed by James Parham, who got his Ph.D. at the University of Hawaii before moving on to a research position at the University of Nebraska.

Parham took existing information about rainfall, stream flows, man-made changes and geology to make a three-dimensional computer model of how much water one would expect in any given stream at any given time.

CINDY ELLEN RUSSELL / CRUSSELL@STARBULLETIN.COM Alison Sherwood, a postdoctoral fellow with the Department of Botany at the University of Hawaii, demonstrated in May how she looks for stream algae at the Waiahole watershed. Stream algae is a main source of food for fish and insects in the area's ecosystem.

Scientists then can hypothesize what creatures one would expect to be in different sections of those streams, based on their preferred habitat. If native fish are not in a stream area that on paper looks like their natural home, the scientists will ask themselves why.

For example, says Nishimoto, the lower part of Kahana Stream has an overgrowth of hau trees, which slow the water. That can make living conditions more difficult or impossible for creatures you'd normally expect to find there.

Taking an inventory of existing life in the streams that feed the Waiahole Ditch will give an indication of stream "health" and provide a basis of comparison in the future, if restoration projects, such as removing hau trees from Kahana Stream, are undertaken.

Here is how it works in the field:

Quadrants on a stream are chosen at random from a master grid, says Glenn Higashi, a DLNR aquatic biologist. A biologist, outfitted in a wet suit, dive mask and snorkel, eases into the water downstream from the target area and inches upstream under water, in hopes of not disturbing any creatures that are there.

The biologist takes notes (underwater, on a special waterproof notebook) on any fish or other aquatic animals observed, as well as the condition of the stream.

Global positioning and altimeter measurements are taken so researchers can return to the exact spot years later.

It is painstaking work.

On a daylong field trip in May, Higashi and Darrell Kuamo'o, a fishery technician, expected to take readings on 20 or so sites on Waianu and Uwao streams in Waiahole Valley. With a three-man team they might get as many as 40 readings.

A cooperative program to gather information about Hawaii streams has been in place since the early 1990s, Higashi said, with 150 of the state's 364 perennial streams monitored at some level.

"All the water users are looking at Waiahole as the initial case of how the courts are going to handle the use of water," Higashi says, standing knee-deep in Waianu Stream after taking a reading there.

Parham's model of what animals one would expect in a given reach of stream should bring the research to a new level, Higashi says, and may help the courts clarify how much water is enough. "This will allow us to grab all the different pieces and put them together."