The city is advancing plans to turn an old utilitarian flood-control canal in Kapalama into an inviting mile-long public recreation destination.

City planners envision turning both banks of the 81-year-old Kapalama Canal into landscaped linear park space with picnic pavilions and a pier overhanging the waterway, bike paths, raised promenades, two pedestrian bridges, numerous trees, lighting and public art at an estimated cost of $80 million.

The city Department of Planning and Permitting sought community input in 2016 that helped produce conceptual designs unveiled in 2017, but has spent the past two years adjusting the plan to accommodate a higher amount of potential sea-level rise.

“Basically, doing the right thing (accommodating 3.2 feet of sea level rise) took a little time,” said Harrison Rue, the city’s community building and transit-oriented development administrator.

On Saturday, the DPP published a draft environmental impact statement for the project that includes a challenging permitting process that could take two years to obtain approvals for dredging and disposing of sediment tested for hazards.

Construction is anticipated in phases with completion by early 2026.

The DPP views the project as especially timely because a nearby planned city rail station next to the canal has prompted interest from developers to add thousands of new homes in the largely industrial area within Honolulu’s urban core.

Such interest includes a master plan by Kamehameha Schools to produce 4,000 to 5,000 new homes largely in towers on land it owns along Kapalama Canal near the planned city rail station projected to open next to Honolulu Community College in early 2026.

Area residents have desired improvements to the canal for decades, according to the city, and Rue said the impetus with rail should help realize the canal park plan.

“Folks in Kalihi have been very patient looking to see their 20-year-old vision for a community park along Kapalama Canal to be realized,” he said. “It’s Kalihi’s turn. It’s time to invest in Kalihi.”

The drainage canal was built by the city in 1939 as a federal Works Project Administration endeavor during the Great Depression, and was designed to prevent heavy rains from flooding land created using fill dredged from Honolulu Harbor.

The canal starts mauka of the H-1 freeway with high rock retaining walls that descend to eroding low earthen banks closer to Nimitz Highway. Kohou and Kokea streets run along the banks of the canal where no sidewalks exist.

In 2015, the city lined the canal with chain-link fencing to deter homeless encampments and dumping that had become a problem.

The draft environmental report said the canal has led to degraded water quality running into Honolulu Harbor, and that part of the improvement plan includes dredging and sediment reduction to improve water quality.

“For decades, we’ve had longstanding issues with the canal,” said Jacob Aki, a lifelong area resident whose family history in Kapalama dates to the 1890s. “It’s been more of a burden.”

Aki, a member of the Kalihi-Palama Neighborhood Board, supports the city’s plan and said it will deliver on a general community desire for more green space.

The DPP’s plan also has garnered support during community workshops and from Joey Manahan, the area’s representative on the City Council.

One substantive change to the project’s design over the past two years is using seawalls, instead of rocky angled embankments, for canal sides to handle long-term sea level rise projections.

The public may comment on the environmental report before Sept. 22. More information on that is at 808ne.ws/31J9WDQ.

If approvals are obtained, construction is slated to be carried out in four phases, starting with dredging and bank stabilization work. Park improvements would be made in three phases, starting with the canal’s middle section and followed by the makai end and then the mauka end.