Brown water advisory keeps swimmers out of Hanalei Bay

Officials issued a brown water advisory for Hanalei Bay on July 22 after heavy runoff pushed sediment and other material from the watershed into the bay. The warning kept swimmers, surfers, paddlers and other ocean users out of one of Kauai’s busiest North Shore beaches while the water remained discolored.

The advisory is more than a visibility notice. Brown water warnings are public health alerts because runoff can carry bacteria, debris and other pollutants into coastal waters after rain, raising the risk of exposure for anyone entering the ocean. Hawaii Department of Health guidance says people should stay out of brown or murky water after rainfall and wait about 48 to 72 hours after rain stops before returning, ideally after the beach has had full sunshine to help clear conditions.

That timing matters at Hanalei Bay, where families, swimmers and paddlers pack the shoreline and where conditions can change fast after a storm. Kauai’s North Shore, including Hanalei Bay, Anini and Tunnels Beach, is especially prone to runoff, while South Shore beaches such as Poipū and Brennecke Beach tend to run cleaner in the rain shadow. Kauai also gets more rainfall than any other Hawaiian island, and Mt. Waialeale is cited at about 450 inches of rain a year. Another long-running water-quality concern is the island’s roughly 10,000 cesspools still in use.

Hanalei Bay has also drawn repeated warnings before. Kauai officials posted a no-swimming advisory there on Jan. 27, 2025, and a brown water advisory was issued for Waioli Beach at Hanalei Bay on June 25, 2025. That pattern underscores the pressure on the county’s Ocean Safety Bureau, the state Health Department’s Clean Water Branch and other alert systems to get the message to beachgoers quickly enough before people enter the water.

Kauai’s beach-water tracking system and advisory notices are built for short-lived but repeatable events like this one, but Hanalei’s popularity means the warning has to move as fast as the rain. The Hanalei Initiative, formed after the catastrophic 2018 floods that disrupted local life and the economy, reflects how closely the community lives with runoff, shoreline damage and the water-quality fallout that follows heavy storms.