Water quality status and bacteria risk rating
📍 In Līhuʻe, Kauaʻi, next to the Kauai Marriott and Nawiliwili Harbor
Kalapaki Beach at Nawiliwili Bay is one of the most chronically contaminated beaches in Hawaii. Surfrider Foundation testing shows a 100% bacteria test failure rate at the Nawiliwili Stream mouth since 2016. Every single sample taken at this location has exceeded the Department of Health's 130 CFU/100mL swimming threshold enterococci per 100mL.
Kaua'i has approximately 14,000 cesspools leaching sewage into groundwater and coastal waters. Nawiliwili Stream collects runoff from the Lihue area and discharges directly into the bay. The contamination is not seasonal or rain-dependent — it is chronic and year-round. A brown water advisory has been active at Kalapaki since December 2025.
Surfrider advocated for warning signs at this beach for over a decade. Permission was granted in 2024, and signs were placed near the Nawiliwili Stream mouth — but not at the main tourist beach area near the Marriott.
Based on: Surfrider Foundation Blue Water Task Force 2016-2024 data, DOH monitoring, 14,000 Kauai cesspools
The Hawaii Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain, even if the water looks clear. At Kalapaki Beach, this rule barely applies because the contamination is chronic. The Nawiliwili Stream mouth has failed every bacteria test since 2016 regardless of recent rainfall. Even on dry, sunny days, bacteria levels at this beach can exceed safe limits.
Worst conditions. Kauaʻi is Hawaii’s wettest island, and Līhuʻe averages 40+ inches of rain per year. Wet season storms flush additional urban runoff, agricultural chemicals, and cesspool overflow into Nawiliwili Stream. Bacteria counts during this period can exceed DOH safe limits by 50–100x.
Still fails every test. Unlike beaches such as Poipu Beach that are only risky after rain, Kalapaki’s contamination is chronic. Cesspool leaching continues year-round. Dry season readings are lower but still consistently above the 130 CFU/100mL EPA recreational threshold.
Extreme conditions. The March 2026 Kona Low storms produced catastrophic flooding on Kauaʻi. Brown water advisories remained active for weeks. Nawiliwili Stream’s bacteria counts during these events are off the charts. Recovery time at Kalapaki is slower than most beaches because the stream continues delivering contamination even after the rain stops.
Nawiliwili Stream flows through residential Līhuʻe and empties directly into Kalapaki Bay. The stream collects runoff from roads, parking lots, and properties — many of which use aging cesspools instead of modern sewage systems. Kauaʻi has approximately 14,000 active cesspools, the second-highest concentration in Hawaii.
Unlike most contaminated beaches that only fail tests after rain, Kalapaki’s stream mouth has failed every single bacteria test since 2016 — rain or shine, wet season or dry season. Enterococci levels routinely exceed the DOH threshold of 130 CFU/100mL for recreational swimming by 10x or more.
The Surfrider Foundation advocated for warning signs at this beach for over a decade. Signs were finally installed near the stream mouth in 2024, but no warning signs are posted at the main tourist swimming area near the Kauai Marriott — just a few hundred yards away from where every test has failed.
Nawiliwili Harbor also sits adjacent to the beach. Commercial shipping and cruise ship activity add to the pollution concerns in this semi-enclosed bay.
Anini Beach (North Shore) and Salt Pond Beach (West Side) are also cleaner options if you want to avoid stream-fed beaches.
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⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent passion project — it is not affiliated with the Hawaii Department of Health or any government agency. Water quality ratings on this site are estimates based on publicly available testing data and geographic analysis. They are not real-time measurements and may not reflect current conditions. “No DOH Alerts” means no advisory is currently posted — it does not mean the water was tested and found safe. DOH only monitors a fraction of Hawaii’s beaches, and some areas have no regular testing at all.
Always verify current water quality conditions with the Hawaii Department of Health Clean Water Branch before entering the water. This site is for informational purposes only and should not be the sole basis for any swimming decisions.
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