Volunteers on Saturday made an estimated 5,000 “genki balls” to throw into the Ala Wai Canal, part of a continuing effort to use microorganisms to clean the polluted waterway.

Hundreds of people gathered in April near the Waikiki-­Kapahulu Public Library to throw the baseball-­sized balls of soil, molasses, rice bran and sludge-eating “effective microorganisms” into the canal. After a few smaller tosses into the canal since, the Eco Rotary Club of Kakaako, the Genki Ala Wai Project and dozens of volunteers gathered Saturday morning near the library to form another 5,000 genki balls.

“To reach our goal of making the Ala Wai fishable and swimmable by 2026, we’ll need around 300,000 genki balls total to be thrown into the canal,” said Jenny Do, president of the Eco Rotary Club, which is involved in other conservation efforts.

This is the second year Do has organized the genki ball event at the Ala Wai Canal. On some tables under a large tent on the grass, volunteers mixed the dry ingredients — sifted soil and rice bran — while others mixed molasses and the naturally occurring effective microorganisms, namely yeast, lactic acid and phototrophic bacteria.

The dry ingredients were then mixed with the wet ingredients and formed into compact, oxygen-free mud balls.

“We need this kind of fine dirt to make the genki balls,” said Susan Swink, a member of the Eco Rotary Club. “I’ve been manning a table to make sure that the balls are the right size and that they’re packed well enough because the enzymes don’t like air.”

The bacteria are contained and fed in the mud balls, with the resulting fermentation taking place over a few weeks. On April 1, volunteers will take the genki balls and toss them into the canal.

Last year the balls were deposited into the water near the library, but this year volunteers will be directed to throw them closer to the middle of the canal, near the Ala Wai Community Garden.

Some 26,000 genki balls have been tossed into the canal since 2019, and since then they’ve been cleaning sludge from the notoriously polluted waters — so much so that wildlife is starting to return.

Schools of mullet, aholehole and other fish not previously present can be seen in the canal, and birds, turtles, rays and hammerhead sharks have been spotted. Most recently there was a report of a monk seal sighting. Hiromichi Nago, technical adviser for the Genki Ala Wai Project, even pointed out an exposed piece of coral near a canal wall during Saturday’s event.

The project has found that since the introduction of genki balls there’s been a drastic reduction in enterococci bacteria, which is found in fecal matter, and an increase in dissolved oxygen and water clarity, both signs the canal water is being restored.

There are smaller tosses throughout the year, and Nago said the goal is to get more genki balls into the canal every month. He said roughly 4,000 have gone into the water since the beginning of the year.

“Our track is to do 8,000 a month until 2026 because we’re trying to hit the goal of 300,000 throughout the whole canal,” he said. “Events like this are going to help.”

Farrah Truong, director of revenue management for the Ritz-Carlton Residences in Waikiki and an Eco Rotary Club member, was able to incorporate genki ball donations as part of the hotel’s Malama Hawaii Program.

With Nago’s help, advocates have been able to get 1,000 genki balls into the polluted Waihonu Pond in Hilo’s Lili‘uokalani Botanical Garden, and Nago said another 1,000 will be thrown into the pond on Earth Day, April 22.