What’s causing weird foam to appear at Santa Rosa Creek?

Some scientists believe a floating mass of foamy goo seen recently near the mouth of Santa Rosa Creek most likely is made up of algae, shreds of kelp, diatoms, other small organisms and other stuff washed over the sand bar by recent high waves from historic-level king tides.

Some locals agree. As former county supervisor and longtime area resident Shirley Bianchi said Dec. 8, “If there are high waves and surf, there will be goo and stuff in the lagoon” and/or lower reaches of a creek.

It would take formal water tests to prove unequivocally what the composition is of the sticky islands, some of which are floating in the creek, with others nestled against weeds, brush and the edge of the creek bed.

Bridget Hoover, water quality specialist for the Monterey Bay National Marine Sanctuary, said in an email Dec. 7 that while the gunky stuff “likely is natural organic matter,” it’s difficult to say for sure without doing water-quality tests, such as for dissolved oxygen, pH and salinity.

Connie Gannon of Greenspace — The Cambria Land Trust, said she’s not 100 percent sure about the nature of the foam. “I know there have been abnormally high levels of several algae in the ocean and in San Simeon Creek, but the lagoon at Santa Rosa Creek was clear most of the summer.”

However, she added that she does think the natural-cause assessment probably is correct.

Gannon added that, unfortunately, “the gunk will stay there until the creek breaks through” to the ocean after more rain falls.

Similar goo apparently is showing up in some other area creeks.

This story was originally published December 10, 2015 at 4:42 PM with the headline "What’s causing weird foam to appear at Santa Rosa Creek?."