If anyone needs another reason not to swim in Big Chico Creek right now, it has turned brown. Opaque, murky water was present on Friday in Big Chico Creek at Sycamore Pool and as far as Forest Ranch after more than two months of a no-swim advisory, placed on Big Chico Creek because of the presence of E. coli that made five people sick this year. … The Chico Parks Department’s best guess is that the turbidity is from runoff caused by thunderstorm activity this week in the foothills.