The 1,000-gallon spill was caused by a blockage in a sewer line in Anaheim, according to the Orange County Health Care Agency.
Orange County health officials closed the bay to water-contact sports between Sunset Aquatic Marina and Portofino Cove Marina on Sunday.
The water is being tested, and the area will stay closed until the water quality meets acceptable standards.
For information regarding Orange County ocean, bay or harbor postings and closures, call (714) 433-6400 or visit www.ocbeachinfo.com. To report a sewage spill, call (714) 433-6419.