SEATTLE - A contractor broke a 20-inch city water main Wednesday morning in the south Lake Union neighborhood, sending a huge amount of water flooding onto area streets.

The broken 20-inch main near the intersection of Dexter and Harrison released a flood of water that disrupted traffic at the Mercer Street ramps to Interstate 5. Water had already flooded into several business along Dexter Avenue before crews managed to shut off water flowing to the broken pipe.

Twenty-six businesses along the east side of Dexter Avenue lost water pressure, leaving them without working sinks and toilets.

There was some minor water damage to nearby businesses, but it could have been worse. By luck, construction crews had some asphalt in the area, and were able to line the fronts of area businesses to keep some of the water from getting inside and limiting damage to some wood floors and carpet.

Nearby, a new University of Washington medical lab building that is being built had about 6 inches of water inside their ground floor, but they too could have fared worse. They happened to have some sheet rock delivered earlier in the morning, so the construction foreman instead had the sheet rock stacked out front as a virtual dam and that kept water damage to a minimum.

"We're focusing on getting this stopped and making sure there's as little damage to local business as possible," said Mayor Greg Nickels. "We'll get people back to normal as fast as possible."

City engineers and firefighters also scrambled to contain the water and prevent it from entering nearby electrical vaults. A little water got into a few electrical vaults but didn't cause problems. Seattle City Light says no one lost power, but some businesses voluntarily cut power just in case.

It was not immediately clear whether the water main was marked or if the contractor knew it was there.

Engineers say some businesses could get their water back by noon, while others might have to wait until later in the evening.

"We have to replace a 12-foot section of pipe," said Joe Mickelson with Seattle Public Utilities. "We're hoping to have the water on between 6 and 8 o'clock tonight."

In the aftermath, engineers say they are getting reports of cloudy water or low water pressure from the Ship Canal area south to near Boeing Field, and from I-5 west to the waterfront, including the entire Downtown Seattle corridor.

Seattle Public Utilities say customers experiencing discolored water are advised to try running the water for a few minutes to see if it is clearing or still discolored. If the water does not clear, let the water sit for an hour. Then run the water for a few minutes and flush the toilet a couple of times. If the water remains discolored, please contact their customer service at (206) 684-3000.