Question 1

Is the Ala Wai Canal contaminated?

Accepted Answer

The Ala Wai Canal carries elevated bacteria levels year-round due to sewage from aging cesspools, storm drain runoff, and urban pollutants. Bacteria concentrations regularly exceed EPA recreational swimming standards by significant margins. The Hawaii Department of Health has a permanent advisory against entering the canal water. A 2026 study published in Nature Scientific Reports found that contamination from the canal directly affects nearshore ocean water quality at Waikiki during rain events.

Question 2

Does the Ala Wai Canal affect Waikiki beach water quality?

Accepted Answer

During and after heavy rain, the Ala Wai Canal discharges contaminated water into the ocean at the western end of Waikiki. This discharge creates a plume of elevated bacteria that can spread along the shoreline. The effect is most pronounced after storms and can persist for 72 hours or more after rain stops. DOH water quality testing at Waikiki shows bacteria spikes that correlate with canal discharge events. Dry-weather conditions typically show much lower bacteria levels because the canal is not actively overflowing.

Question 3

What did the 2026 Nature study find about Waikiki flooding?

Accepted Answer

A 2026 study published in Nature Scientific Reports (DOI: 10.1038/s41598-026-38225-z) found that 100% of Waikiki storm drainage outfalls will fail by 2050 due to sea level rise and groundwater table changes. The study modeled compound flooding scenarios showing that even moderate rain events will cause widespread flooding in the Waikiki area, overwhelming the canal system and increasing contaminated water discharge into the ocean. This means water quality problems at Waikiki beaches are projected to worsen significantly over the coming decades.

Question 4

Can you swim in the Ala Wai Canal?

Accepted Answer

No. The Hawaii Department of Health maintains a permanent advisory against entering the Ala Wai Canal. The canal water contains sewage-related bacteria, heavy metals, and urban pollutants at levels far exceeding EPA recreational swimming standards. Contact with the water can cause serious illness. In 2006, a paddler died from a flesh-eating bacteria infection after falling into the canal. Canoe paddling clubs that train on the canal take precautions including avoiding water contact and showering immediately after practice.

Question 5

Why is the Ala Wai Canal so polluted?

Accepted Answer

The Ala Wai Canal was built in the 1920s to drain wetlands for Waikiki development. Today it receives runoff from three major streams (Manoa, Palolo, and Makiki), storm drains from urban Honolulu, and seepage from thousands of aging cesspools in the watershed. Hawaii has approximately 88,000 cesspools statewide, and a significant concentration exists in the Ala Wai watershed. During heavy rain, the canal system is overwhelmed, mixing sewage, animal waste, pesticides, and other pollutants before discharging into the ocean near Waikiki.

Question 6

When is Waikiki water quality worst because of the Ala Wai Canal?

Accepted Answer

Waikiki water quality is most affected by the Ala Wai Canal during and after heavy rain events, particularly during the wet season (October through April). Kona storms and other heavy rain events can cause the canal to overflow, sending contaminated water directly into the ocean. The worst conditions typically occur within 24 to 72 hours after heavy rainfall. The western end of Waikiki (near the Hilton Hawaiian Village and the canal outlet) is most affected. The eastern end near Kaimana Beach is generally cleaner because it is farther from the canal discharge point.

Question 7

Is there a plan to clean up the Ala Wai Canal?

Accepted Answer

The U.S. Army Corps of Engineers has proposed a flood mitigation project for the Ala Wai watershed, estimated at over $345 million. The project aims to reduce flood risk through detention basins, floodwalls, and improved drainage. Hawaii has also passed legislation to convert cesspools to septic systems or sewer connections by 2050, which would reduce a major source of contamination. However, the 2026 Nature study suggests that sea level rise may outpace these improvements, as rising groundwater will compromise drainage infrastructure regardless of cesspool conversion.

Ala Wai Canal Water Quality

During Dry Weather

During & After Rain

100% of Waikiki Storm Drains Will Fail by 2050