Tests show Bay water is clean

Although concerns of residual oil from the Nov. 7 Cosco Busan spill still linger around the Bay, two separate tests have shown no conclusive proof that fuel has threatened an important fishery in the North Bay or a shipping channel in Oakland.

There were concerns that residual fuel may have sunk — by becoming attached to pieces of dirt or sand — into the sediment around Oakland’s shipping channels, impeding the Oakland 50 dredging project.

But a test done this morning came back conclusively clean, with no sign of Cosco Busan oil or other contaminants, Army Corps of Engineers spokeswoman Maria Lee said.

The project — to deepen the channel to 50 feet by removing approximately 12 million cubic yards of sediment — is contributing more than 2 million cubic feet of that dirt to the Hamilton Wetlands Restoration Project.

“Before we do any dredging, especially when it involves material placed in a reuse site, all the material is tested,” she said. “We planned for this testing a long time ago, but this was an extra precautionary note after the Cosco Busan spill that the Corps decided we should do.”

Additionally, state officials said that tests conducted by a California Department of Fish and Game biologist last week that found what seemed to be oil found in local herring fisheries were “inclusive,” according to Lt. Rob Roberts of the Department of Fish and Game’s Office of Spill Prevention and Response.

Roberts added that the collection was not done to state standards and that his agency will be retesting the area this weekend.

The fishery in question is a section of Bay covered in eel grass — like thick, long blades of grass — that acts as a nursery for herring.

“We couldn’t tell if it had actually come from the eel grass, it was contaminated so we don’t know where it came from, so we’re going to do a more controlled sampling process,” he said. “The sampling wasn’t done in the most scientific way, and because this is a criminal case, we need those standards to be in place.”

In both cases, the water is tested using groups of “pompoms” just slightly larger than a basketball dragged by boats. The absorbent plastic material of the pompoms — similar to Swiffer kitchen cleaning wipes — is then analyzed for oil or other materials.

Damage to Bay habitats or shipping channels would become part of any criminal cases against the Cosco Busan’s owners, which would likely include assessed values to any damaged environments or species, Roberts said.

jgoldman@examiner.com

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