The spill, which was reported at about 8:15 a.m. Monday, came from a 60-foot, 90-ton tugboat that was in the process of 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 two-mile sheen that stretched from Hopper Street to U.S. Highway 101, Retallack said.
As a precautionary measure, officials are not allowing fishing from the shoreline or by boat in the area between the Payran Street bridge and U.S. Highway 101. The ban is in effect until further notice.
"We put that in place because of sheening in the area," Retallack said. "We just want to make sure everything's safe."
No adverse effects to wildlife have been reported so far in connection with the spill, according to Retallack. The sheen had mostly evaporated by Monday evening, but authorities continued to monitor the area today.
A vacuum truck was brought in to suck the remaining oil off the boat late Monday night and today, she said.
Some of the oil remained on the boat when crews stopped at about 2 p.m., when the high tide came in, Retallack said.
The tail end of the boat is in the water while the rest of it is on the riverbank, she said.
Authorities hope to remove the vessel from the river Wednesday.
"The goal is to get the ship out of the water because then we don't have a spill threat anymore," Retallack said.
Crews are still investigating what caused the leak and have placed absorbent boom in the water to remove the oil and stop the sheen from spreading, 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.