Water fight: Lots of work to curb erosion along Hood Canal on State Route 106 in Mason County

By: April Leigh 

State Route 106 meanders along an idyllic landscape of water, rock and treed hillsides.

SR 106 is a two-lane highway along the Hood Canal in Mason County.

But when you couple strong storms with king tides at this picturesque spot, it’s a recipe for roadway flooding.

Heavy rains cause higher, faster water to run down the hill on one side. On the other side, higher tides can surge and overwhelm drainage systems.

Destructive waters

We’ve seen mother nature’s destructive touch on this road firsthand. Over the last three years we’ve had to close portions of SR 106 several times due to flooding. We’ve also had to fix several slides along the shoulder where steep hills meet the highway.

A slide closed SR 106 for several hours at milepost 2.4 after heavy rains in November 2024.

Most recently, our maintenance crews have focused on shoreline erosion along the side of the road near Hood Canal. Steeper areas have slowly eroded. In some places you can see where the embankment has inched closer to the shoulder of the road.

An embankment fell and closed the shoulder of SR 106 at milepost 2.9 in April 2025.

A soggy uphill battle

This time of year, our maintenance crews are gearing up for another season of fighting water on SR 106. It will be a bit different this year though. During the wet months ahead, they’ll closely watch a series of new hillside repairs built this summer.

Maintenance crews use biodegradable mats and vegetation to shore up an embankment next to SR 106 along the Hood Canal in Mason County.

From May through September this year, we built erosion control projects at 17 spots along the 20-mile highway.

Crew members are no strangers to this type of erosion control work on SR 106. However, completing 17 projects in one summer is a huge achievement, particularly when you consider how close the work is to the shoreline. Before we begin construction, we have to understand how the work will affect the environment. We also have to get engineering approvals and all the right permits.

During construction, we rebuilt rock walls at some locations. We reinforced other locations with biodegradable fabric and plants to help hold the hillside in place.

This work is designed to slow the water down and promote a better environment for wildlife along the canal.

It’s an uphill battle though. Each of the 17 locations completed this summer were prioritized based on need at the time.

There are more than 40 other locations along this highway currently identified for repairs. And that list gets longer and changes every time we have a strong storm event at the same time as a king tide. We plan to complete more sites in the coming years, but a lot depends on priority, available resources and mother nature.

Maintenance crews use an excavator to place boulders along a newly rebuilt retaining wall beside SR 106.

The work on SR 106 is just one kind of work our crews focused on this summer. Our summers include many types of projects that help prepare our roads and bridges for the upcoming rainy season.

See more photos of summer maintenance work in 2025 in Olympic Region.

Help prevent roadside flooding

Roadside flooding is not just a problem along SR 106. It’s everywhere in western Washington. Soon, we’ll see water rush down steep hills, flood storm drains and pool on roadways.

If you live near a state highway, you can help reduce the chances of roadside flooding. Here are some preventative maintenance tips for your property:

• Clean out your roof gutters
• Keep your storm drains clear
• Check your driveway culverts for debris