It’s easy to think otherwise, but the Department of Health issues brown water warnings when polluted water makes it unsafe for you to swim, not when a new Starbucks opens.
And if you’re caught off guard in the water, things can really turn bad. So to help save you from this brown water surprise, scientists at the Pacific Islands Ocean Observing System (PacIOOS) created a new tool that forecasts where and how much brown water might run out into the ocean from the Ala Wai Canal.
Called the Ala Wai Turbidity Plume Model, it monitors the Ala Wai, which is special because it funnels a lot of the polluted runoff from Makiki, Manoa, and Palolo’s streams and dumps it into the Ala Wai Harbor. But where does it go from there, and will it affect your surf session at Bowls, Kaisers, or Rockpiles? The PacIOOS tool hopes to answer these questions.
Here’s what happens: After it rains, tiny solids suspended in the water column get washed out, confusing the clarity of the water, or the turbidity level. More solids (which can be anything from household chemicals to leptospirosis to poop), equal cloudier, browner water. The cloudier the water, the more likely it is to ruin your day.
The Plume Model uses near real-time data of runoff and turbidity for the canal in a “Regional Ocean Modeling System” forecast, and will present the forecast in an animated map. It also predicts where the affected water might go after leaving the Ala Wai, good info for south shore surfers.
In addition to the plume tool, PacIOOS also does cool things like track tiger sharks and predict rising sea levels for Guam and Palau. And if you want to check on water clarity for other, non-Ala Wai waters, PacIOOS monitors that here.