The oil spill, which was reported at about 8:15 a.m. Monday, came from a 60-foot, 90-ton tugboat that was being salvaged, Department of Fish and Game spokeswoman Alexia Retallack said.
Between 200 and 600 gallons of lube oil spilled into the river, creating a 2-mile sheen that stretched from Hopper Street to U.S. Highway 101, Retallack said.
Crews spent most of today trying to figure out how to safely pull the boat out of the water but stopped at about 4 p.m. to reassess, she said.
The plan was to separate the boat into three parts because separating it into two parts was "still too big for us to handle," she said.
"We're going to come back tomorrow and look at what we want to do, and if the equipment we have will work, or if we need to bring in more equipment," Retallack said.
On Tuesday, officials placed a temporary ban on fishing from the shoreline or by boat in an area of the river between the Payran Street bridge and Highway 101. The ban was lifted as of 10:30 a.m. today, she said.
There have been no signs of wildlife affected by the spill.
"We've had biologists go around with cleanup crews and will do more surveys" Thursday to ensure no animals are harmed by the spill, Retallack said.
There are still three absorbent booms in place in different areas of the river, but others have been removed because "we have most of the oil collected," she said.
Investigators are still looking into what caused the leak during the salvage of the boat, which was owned and being dismantled by ATOP TRC Inc., an Alameda-based salvage company, according to Retallack.
She said local, state and federal officials are working together to determine the costs of the response and cleanup, which the responsible party will be liable for.
"The goal is that taxpayers do not pay for pollution like this," she said.
Anyone who sees wildlife on the shores of the river near the spill is asked to call the Oiled Wildlife Care Network at (877) UCD-OWCN rather than try to help the animal.
Anyone whose boat might have gotten oil on it from the spill is asked to contact the U.S. Coast Guard's National Pollution Funds Center by filling out a claim form that can be found at http://www.uscg.mil/npfc. The code for claims connected to this spill is E10911.