Beaches in Parts of Newport Bay Closed by Spill : Health: Sewer leak near Fashion Island is repaired, but affected shoreline won’t reopen to swimmers until Wednesday.

Health officials closed beaches on parts of Balboa Island and Corona del Mar to swimmers Sunday after two sewer pipe plugs blew off near Fashion Island shops, sending a stream of raw sewage down storm drains and into Newport Bay for more than four hours.

The plugs, capping a small pipe that branches off the main sewer pipe underground, blew off about 7 a.m., after the main pipe became blocked and sewage backed up into the smaller pipe near a Fashion Island parking lot, Fire Department Capt. Dave Bowman said.

The leak was not reported to authorities until 11:35 a.m., Bowman said, after the sewage had been flowing down storm drains and into the bay about three-quarters of a mile away for several hours. No hazardous chemicals were contained in the spill, he said.

As a precaution, a county Health Care Agency official barred swimming on Little Island (the part of Balboa Island east of the Grand Canal) and on the mainland shoreline from a point opposite Little Island south to the harbor entrance jetty. The area, mostly made up of private beaches and docks, is expected to remain closed until Wednesday, Bowman said.

Restaurants in the Fashion Island area turned away customers until the spill was cleaned up Sunday afternoon, Bowman said.

No estimates were available Sunday on the size of the spill, but the leak wasn’t “gushing,” Bowman said. “We’re not talking huge quantities. It was not a big geyser.”

The main pipe, leading from Fashion Island businesses, was under a great deal of pressure because many of the businesses are two and three stories high, Bowman said. The smaller pipe, called a “clean-out,” was a connection put in so that plumbers could easily clean out a clog in the main pipe.

Fire officials and employees of the city’s General Services Department initially responded to the spill by building six- to eight-inch dikes with earth from nearby planters to stop the flow of sewage into storm drains.

“We diked up the streets and gutters, then started collecting the sewage,” Bowman said. By 2:15 p.m., Bowman said, the pipe was unclogged and the caps were replaced on the clean-out pipe.