The state Department of Land and Natural Resources is starting a $21 million-plus Ala Wai dredging project this month — good news for those who have been waiting nearly two decades to get relief from the buildup of sludge, sediment and debris in the man-made canal.

DLNR said a recommended dredging interval is every 10 to 12 years, and the canal was last dredged in 2002 and 1978.

DLNR’s Engineering Division said its contractor Hawaii Harbors Constructors JV will dredge the canal to depths ranging from 6 to 12 feet, removing about 186,000 cubic yards of buildup, accumulated silt, and sediments.

Many people in Waikiki had hoped that the crumbling canal walls would be attended to during the dredging project. But DLNR’s engineering division said “to repair all of the remaining damaged walls could cost in the millions of dollars, depending on the severity of the damage and the proposed fix.”

Still, DLNR did obtain a state Legislature appropriation this past session to repair the deteriorated section of the canal walls on the mauka side fronting Ala Wai Community Park and between the Kalakaua Avenue and McCully Street bridges.

Work hours for the yearlong project are 7 a.m to 10 p.m. Monday to Saturday and 9 a.m. to 10 p.m. Sunday and holidays.

Dredging is expected to help maintain the canal’s ability to efficiently move storm water to the ocean, reduce the risk of flooding and improve recreational use of the canal, DLNR said. It also will bring the canal’s recreational users and nearby residents and businesses some relief.

A controversial Army Corps of Engineers Ala Wai Canal flood management project is intended to protect Waikiki and several other Oahu neighborhoods from flooding by putting walls and berms around the canal and flood-control structures in the upper reaches of the watershed.

But many consider the dredging project overdue.

Lifelong paddler Henry “Kruiser” Kruse said parts of the Ala Wai Canal have grown nearly impassible for outrigger canoes since the state last dredged.

“I’ve been paddling on the Ala Wai Canal since 1977, and conditions are worse than they’ve ever been,” said Kruse, the head paddling coach at Roosevelt High School and the assistant paddling coach at the Waikiki Yacht Club. “I support the dredging. There are places up on the mauka side from the Marco Polo condominiums to ‘Iolani high school where you can’t paddle a canoe without hitting mud.”

Still, Kruse said paddlers will have to watch for equipment and worsening conditions just as high season goes into full swing for the seven or eight school teams that paddle the canal.

“It will affect the paddlers, but how much depends on how they do it. Last time, they used barges and a floating crane and it only took about half of the Ala Wai Canal,” he said. “The bad part is once they start stirring up the canal, the bacteria gets really high and you’ll see a lot of cases of staph infections and boils.

Once the dredging starts, Kruse said he’ll move his paddlers closer to the entrance to Ala Moana Park.

Waikiki Neighborhood Board member Kathryn Henski said she also supports the dredging, but she doesn’t think that people are truly prepared for the impacts that will come while the project is ongoing.

“There are trees growing out of the bottom of the Ala Wai Canal and I’m sure they’ll be pulling out shopping carts, mopeds, bicycles and other debris, ” Henski said. “This project is needed, but I don’t think people are going to be prepared for the stench and other disruptions.”

Henski said she’s also concerned about the timing of the project, which may increase congestion in Waikiki when projects like the Hilton Grand Vacations Club at the former King’s Village site and Brookfield Properties’ Lilia Waikiki project are moving forward.

“I think we’ll get a lot of complaints from people who aren’t prepared for the stench and the debris and the noise, especially since they are working seven days a week and holidays. It’s also going to be really crowed around Kapahulu Avenue and Ala Wai Boulevard,” she said.

But Rick Egged, president of the Waikiki Improvement Association, said the benefits of the dredging outweigh the inconveniences. Egged said he expects canal work to create some noise issues, but few parking or traffic disruptions.

“The main purpose of the canal is to divert the streams’ flows out to Waikiki and into the ocean to create dry land. Silt buildup reduces the canal’s capacity so it’s good that we get this done,” Egged said.

Waikiki Neighborhood Board chairman Bob Finley said keeping the Ala Wai Canal at optimum depth is one of Waikiki’s No. 1 protections against flooding.

“When there’s less depth to the canal, there is less room for water and more opportunity for water to overflow,” Finley said.

“When the canal overflows after a heavy rain, a lot of water comes out of the Ala Wai and into Waikiki basements. The elevator in my condominium building has gone out because the elevator sub pump filled with water and I’ve heard of a number of other buildings that have been similarly impacted. That should be a wake-up call. It’s time.”

GETTING DIRTY

The Ala Wai dredging project will start this month on an unspecified date:

>> Cost: $21 million plus

>> Contractor: Hawaii Harbors Constructors JV

>> Project hours: Monday- Saturday, 7 a.m to 10 p.m.; Sunday and holidays, 9 a.m. to 10 p.m.

>> Depths to be dredged: 6 to 12 feet

>> Buildup to be removed: 186,000 cubic yards

>> Previous years dredged: 2002 and 1978