Here’s why San Diego’s waves have turned pink

Visitors to Torrey Pines State Beach in San Diego this week may have seen something they struggled to believe: pink waves rolling in from the Pacific Ocean.

But the pink hue to the normally blue-gray water is not a mirage: it’s part of a Scripps Institution of Oceanography project to discover more about how salt water interacts with fresh water near the shoreline.

To see clearly what kinds of reactions are happening, researchers with the University of San Diego-based institution released a non-toxic pink dye into the nearby Los Peñasquitos Lagoon coastal estuary. That dye helps researchers see what happens when some of that fresh lagoon water ends up in the surf zone along the beach.

“I’m excited because this research hasn’t been done before and it’s a really unique experiment,” said Sarah Giddings, a Scripps coastal oceanographer, told the UC San Diego website. “We’re bringing together a lot of different people with different expertise, such that I think it’s going to have some really great results and impacts. We will combine results from this experiment with an older field study and computer models that will allow us to make progress on understanding how these plumes spread.”

The researchers are using a vast array of tools to track the progression of the dyed water, including drones, sensors placed in the river and ocean, and a “jet ski outfitted with a fluorometer.”

The results of the ongoing study are expected to provide critical insights into the speed at which sediment, pollutants, larvae, and other materials are spreading near the shore.

The research outfits says that the pink dye noticable to members of the public poses absolutely no threat to the environment, though the university is urging beachgoers to move their base operations away from the estuary on dates when the pink dye is released.

The dye is visible to the human eye for several hours after it is first released, but can be sensed by research sensors for 24 hours.