SEATTLE -- State transportation officials have acknowledged the new State Route 520 bridge over Lake Washington was "structurally deficient" months before it opened to traffic in April 2016.

The determination came from an inspection given to the Federal Highway Administration. It was included in a report published Wednesday by an association of road builders.

At issue were the majority of anchor cables that connect the bridge span to anchors at the bottom of the lake. After installation, "kinks or anomalies" were found in 46 of the 58 cables. Washington's Department of Transportation decided to have them all replaced. To date, most of them have been swapped out.

"They already passed the strength test," said WSDOT spokesperson Steve Peer, "But, we want (the cables) to pass our longevity test as well."

Cables are expected to last at least 20 years, and Peer said that was in doubt.

"It's really a difficult thing to determine whether it was in the spooling, how we installed them, in the design, if it was a manufacture default," said Peer, "The main thing is it was there."

However, because the strength of the cables was not in question, the bridge was deemed safe and opened in April before the replacement program began.

Peer said the cable replacement will not cost taxpayers any extra money, though an exact figure was unavailable Thursday night. The cables were included in a recent $2 million change order, but according to Peer, was not the only item on the order.