A demonstration project that uses plants to clean parts of the Ala Wai Canal is working but it has a long way to go before the polluted urban waterway is safe for swimming or fishing, officials with a private company say.

Early data from the year-long experiment show the floating plants have reduced the amount of nitrogen, bacteria and algae in the canal and increased visibility where they are anchored, near the Waikiki-Kapahulu Public Library and along the bank from the city golf course to the Manoa-Palolo drainage canal.

"The water has become more clean," said Wenhao Sun, vice president of Marine Agritech and principal investigator for the project. "It has become safer and the nutrient levels reduced due to the system of plants."

Sun declined to release testing data until an official report is issued, but said the monthly testing shows dramatic reduction in pollutants. The water is cleaner with more fish and birds living and feeding in the area, he said. The plants do not remove heavy metals such as lead, mercury and copper, which were found in the mud during a dredging of the canal in 2003.

Last April, Natural Systems Inc. was given permission to conduct a one-year demonstration project in the canal. Natural Systems partnered with Marine Agritech to place thousands of 'akulikuli plants on floating rafts with their roots dropping 3 feet into the water. Bacteria and microorganisms colonize the roots and improve water quality through their nutrient uptake.

The process is known as phytoremediation, or using plants to treat environmental problems.

"From the reactions we've had so far, we are encouraged," said Peter Young, chairman of the state Department of Land and Natural Resources. "It appears to be an effective way to deal with water quality that is relatively benign. We will be getting a more formal report later, but the preliminary indications we heard have been very encouraging."

Working with a $500,000 grant from the U.S. Department of Agriculture's Biosystems Technology Program, the companies grew the plants in a nearby drainage canal and placed them in the Ala Wai.

The report will be presented to the state by April.

Koalani Lagareta, a teacher at Halau Ku Mana Public Charter School, brought her middle school class to study the process yesterday.

The students are testing water quality, propagating the plants, making rafts and studying the history of the area.

"Our project is based around water usage and quality," Lagareta said. "Science, social science and math are all integrated into this one project. If you are talking about microorganisms in the water and ecology in the classroom and they never get a chance to actually see how those systems affect one another, then it's almost too abstract. It's been a really great resource for us to come down here."

The Ala Wai Canal is not a stream but part of the island's drainage system and is polluted by urban chemicals washed down from vehicles and homes. The canal is heavily used by canoe paddlers and kayakers. Staph infections are common when the canal's water gets into an open wound. The state Department of Health has posted signs warning people not to swim or eat fish caught in the canal and suggests that anyone who falls in the water should take a thorough shower as soon as possible.

Halau Ku Mana student Hae Ani, 14, is a canoe paddler and winces when recalling the time her boat tipped over, sending her into the water. Ani said it is fun to come down to the canal and see improvements in the water quality and environment.

"We are learning about how we can clean our water without using more chemicals," she said. "It is better then regular classes where you just read about it."

Chad Durkin, project manager for Natural Systems, said he is hoping the test results will lead to more grants to extend the work along the length of the canal.

Durkin has worked with students from 20 public and private schools to study the process and results of the phytoremediation. He said teaching children and the public to care for the environment can do a lot more in the long run than just working to improve one waterway.

"The Ala Wai is just one of more than 18 water bodies in the state," Durkin said. "If you fix one, it's nothing. But if you can change the mindset of people, eventually it will impact all the water bodies here and hopefully spread around the world. (Pollution) is a global problem."

Reach James Gonser at jgonser@honoluluadvertiser.com.