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SR 520 - Floating Bridge and Landings Project: Boater Information

Key resources for drivers and boaters

SR 520 Bridge Information page

More info on WSDOT movable bridges

Updated: Oct. 12, 2016


Construction activities continue near SR 520

Due to the volume of construction activities taking place near the floating bridge and near the new West Approach Bridge North, boaters should be vigilant and boat with care. Using appropriate boater etiquette and following speed limits near construction activities will keep both boaters and construction crews safe.

The east and west navigation channels will be periodically blocked for critical construction activities. During these blockages, marine vessels should plan to navigate through the unaffected channel (see below for navigational height restrictions). Please note that one navigation channel will always be open and accessible to boaters. 

To receive updates about upcoming blockages of the navigation channels, email us.

Navigation restrictions

East navigation channel fully obstructed through Monday, Oct. 31

The east navigation channel will be fully obstructed through Monday, Oct. 31. Vessels with vertical navigational clearance of more than 44 feet can request to have the east channel obstruction moved by contacting:

  • Calling Matt Steffens at 425-749-6675 or emailing him at
  • Contacting the Big Eagle on VHF channels 16 or 20-Alpha.

The eastern navigation channel will have a horizontal clearance of 256 feet and a vertical clearance of 70 feet when open to marine traffic.

West navigation channel open to boaters

The west navigation channel is open to boats with a navigational height of 44 feet or less. The west navigation channel has been opened with a varied horizontal clearance between 94 feet and 150 feet. Mariners should use caution while navigation this channel due to the varied channel widths.

Please note that one navigation channel will always be open and accessible to boaters during the decommissioning process.

Navigation channel restrictions
Navigation changes on Lake Washington at SR 520. Click image for printable version (pdf 684 kb).

Safety precautions

Mariners should maintain a safe distance and minimize wake around all floating derrick barges and other construction vessels within the SR520 project area.

Mariners are advised to use caution while transiting near derrick (crane) barges and work barges within the SR520 project area. These vessels are currently anchored and may present submerged hazards. Work zones around some derrick barges have been marked with red/white buoy strings. Mariners should maintain a safe distance and minimize wake around all floating derrick barges and other construction vessels. Demolition of these piers and columns is continuing through Wednesday, Nov. 30, 2016 and will present hazards to approaching vessels.

The pontoons that made up the old SR 520 bridge will be transported from Lake Washington to Shilshole Bay through December 2016. Exclusion area buoys and signage will mark the four Pontoon Alpha submerged anchor wires near the west navigation channel (enclosure 4). Mariners should avoid passing through active demolition work in this zone.

12 temporary barge mooring pilings have been placed on the north side of the bridge just west of the east navigation channel and marked with quick flashing yellow lights (QY), which may be obscured at times when barges and other equipment are moored at the site. Eight temporary white mooring buoys (six on the north side and two on the south side) marked with white lights flashing every 4 seconds and blue retroreflective tape have been relocated near the bridge for the mooring of the deconstructed old bridge sections.

East navigation channel clearance under the new SR 520 floating bridge

Once the east navigation is reopened, boaters will see two signs indicating clearance. Both signs are gauges posted at the water level to show the clearance for boaters at the current water level. The graphic below shows the east navigation channel clearance under the new SR 520 floating bridge.

The only sign currently posted on the bridge is on the pontoon located at the west side of the channel. While this sign is a gauge, as shown below, this sign will always show a clearance of 70 feet at water level since the pontoon rises and falls with changes in water levels on Lake Washington.

A sign will be posted on the fixed, east approach column at the east side of the channel. The clearance is 65 feet at the east end of the channel so boaters will see that portion of the sign at water level. As water levels lower, the clearance on the east side of the channel may rise up to approximately 67 feet. 

East navigation channel gauges

East navigation channel height of the new SR 520 floating bridge. Click on the image above for a larger, printable version (pdf 6.3 mb).

Decommissioning update

The pontoons from the old floating bridge will continue to float out through the Hiram M. Chittenden Locks for the remainder of the year. There are also a variety of other decommissioning activities happening in and around the SR 520 navigation channels. Please view our decommissioning factsheet (pdf 1 mb) to learn more about some of the upcoming bridge-removal activities and what you can expect to see in the water.