Crews continue to remove coolant fluid from electric cables that sprang a leak in the Straits of Mackinac earlier this week.
The U.S. Coast Guard says about 600 gallons (2,271 liters) of mineral-based synthetic oil escaped into the waterway linking Lakes Huron and Michigan. The cables are operated by Wisconsin-based American Transmission Company, which has taken them out of service.
A company contractor is removing about 800 gallons (3,028 liters) of oil remaining in the two damaged cables. The Coast Guard says about 10 percent was sucked out Wednesday.
Officials say there's little risk to the public or wildlife because the fluid will be diluted, while heavy shoreline ice should prevent anyone from coming in contact with the oil.
Coast Guard air crews haven't spotted any oil on the surface.
