The Coast Guard said Saturday that an area of discolored water near a Mississippi River pass south of New Orleans appears to be an algae bloom, but another spot 10 miles away could be oil.

Jeff Hall, spokesman for the Unified Area Command, said tests could determine if the suspected oil is from the BP spill. The Coast Guard sent two flights over the West Bay area near Venice on Saturday. Two boats also went out to check the waters.

New Orleans Times-Picayune: Massive stretches of weathered oil spotted in Gulf of Mexico

Hall told The Associated Press that tests will be done Monday on water samples from an area where a marine investigator believes there's an algae bloom near Venice. The area of discolored water there was about 2.5 miles long and 300 yards wide, Hall said.