SEATTLE - The Washington State Department of Transportation is looking for the boat or barge that hit an underwater cable that connects one of the 520 bridge pontoons to the bottom of Lake Washington.
The severed cable was discovered early Tuesday morning during a routine inspection.
It happened in a restricted zone, on the north side of the bridge.
"This cable was impacted between 80 and 100 feet out, roughly 20 feet below water line,” said Dave McCormick, WSDOT’s regional maintenance engineer.
There are several contingency cables, so the bridge was not at risk of floating out of alignment.
The 520 bridge has remained open since the discovery.
Workers are going to string a new cable Friday and Saturday.
There's not a detection system to alert the engineers if a cable has been compromised, so WSDOT officials are thankful the problem was caught during a routine visual inspection.
Figuring out who struck the cable will be a difficult task.
There aren't any cameras that would have seen a ship or barge in the restricted area.
But engineers said it would have to be a big vessel, which sits at least 20 feet below the surface.
The DOT is filing a report with the Coast Guard to help find whoever is responsible.
Officials are also checking with the contractors who are building the new 520 bridge, to see if one of their vessels may have struck the cable.
It’s going to cost roughly $200,000 to repair the damage.
The WSDOT plans to go after whoever broke the cable to recoup those costs.