Skip Top Navigation

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: March 23, 2017


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

West navigation channel closure extended through April 7

The west navigation channel closure will be extended through April 7, as crews install the anchor for the final, permanent navigation buoys. While the west navigation channel is closed, boaters can continue to use the east navigation channel.

East navigation channel open

Pier removal continues near the east navigation channel, but the channel is open with a navigational clearance of 70 feet and a horizontal clearance of 256 feet.

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

Navigation changes on Lake Washington at SR 520. Click image for printable version (pdf 301 kb).

Safety precautions

While all of the pontoons and much of the other marine equipment has been removed from the lake, mariners should continue to maintain a safe distance and minimize wake around all floating derrick (crane) barges and other construction vessels within the SR 520 project area.

Mariners are advised to use caution while transiting near derrick 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.

East navigation channel clearance under the new SR 520 floating bridge

At the east navigation channel, 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).


Nautical mile markers

The new SR 520 floating bridge has nautical mile markers to indicate distance for boaters on Lake Washington. The markers are placed on both the north and south side of the bridge. The graphic linked below shows the layout for the nautical mile markers.

Nautical Mile Marker
Click on the image above for a larger, printable version (pdf 4.16 mb).

Decommissioning update

All 31 pontoons from the old floating bridge have now floated off the lake through the Hiram M. Chittenden Locks, with the final pontoon departing on Jan. 14, 2017. There are a few final decommissioning activities happening in and around the SR 520 west navigation channel, currently planned to be complete by the end of February. Please view our What’s Happening Now? webpage to learn more about some of the upcoming bridge-removal activities and what you can expect to see in the water.