The public is allowed to enjoy the water at Lake Siskiyou again after the lake next to Mount Shasta City was closed to swimmers Tuesday afternoon. A bright green substance was found near the north shore of the lake, and officials urged the public to stay out of the water. A laboratory determined that the substance was an approved food-grade coloring used to test storm drains. Apparently an excessive amount was released which caused the concerning green color. The lake reopened to swimming Wednesday.