ON THE WATER: Group scans ash flow

The recent Santiago Canyon wildfires polluted not only the air, but also the water. Fortunately, though, Costa Mesa researchers say debris basins built to stop the flow of ash into the ocean are working.

Those are just some of the findings scientists associated with the Costa Mesa-based Southern California Coastal Water Research Project have reached as they turn their attention to the effects of the wildfires on local watersheds.

Eric Stein, a scientist with the group for six years, led similar studies of 2003 wildfires in Simi Valley. Data from that study has helped him with this project.

In 2003 he compared heavily scorched land with property farther south, which escaped much of the damage. The more scorched parts of the watershed had more runoff, sediment deposits and metal and organic contaminants, Stein said.

There were also high levels of PAHs — a byproduct of burning organic materials. Fire sends it adrift, and it heads toward the land and water. It can be fairly toxic, Stein said.

Fires tend to vaporize chemicals, like mercury, and lift them into the air through the smoke, Stein said. When the toxins settle on land, they can wreak all kinds of havoc on natural habitats, he added.

Researchers found that the sediment in the watersheds took three-to-seven years to dissolve.

“Santiago Creek Watershed is an interesting case. Up there by the toll road you have a series of debris basins paralleling the 241,” Stein said. “If those debris basins function as they are designed, then they should capture a lot of the material before it gets down to the Newport Bay watershed.”

Officials just have to watch out for storms that could overflow the basins.

More urban areas such as Marina Del Rey and Los Angeles showed contamination “six times higher than what we normally see in normal urban runoff,” Stein said. But once the ash settled down, it washed away considerably after three or four storms.

“My guess would be that the nature of urban areas allows the deposits to wash off more quickly as there is concrete and makes the runoff much more efficient, although not necessarily in a good way,” Stein said.

After the recent Santiago Canyon fires, the group observed scorched land and other areas that escaped the flames, but were affected by the ash.

“We focused on metals and organic contaminants, and we definitely saw tantalizing results,” Stein said. “The problem that we have was that we were just able to sample a couple of storms, nothing to hang my hat on.”

KELLY STRODL may be reached at (714) 966-4623 or at [email protected].