Flood season has arrived in the Snoqualmie Valley, where every town is either in the Snoqualmie River’s 100-year floodplain or adjacent to it.

Unlike other large Washington rivers, the Snoqualmie River runs wild, with no large dams to control it. As beautiful as this makes the river, it can be equally dangerous during the flood season months of November to April.

This year, officials are warning of the added effects of the La Nina winter, which brings cooler and wetter weather to the Pacific Northwest. Local experts agree that Snoqualmie Valley residents should stay up-to-date on helpful flood information.

North Bend in particular has a high flood risk caused by two rivers in the city: the Middle Fork Snoqualmie River and the South Fork Snoqualmie River, which flows right through downtown. According to the city’s website, 42% of North Bend, mostly the west side, sits in the 100-year floodplain.

“If and when the 100-year flood happens, the water level on city streets could be up to 3, 4, 5 feet deep in places,” said Mark Rigos, North Bend Public Works director.

The name “100-year flood” may sound daunting, but it simply describes how likely a flood of a certain magnitude is to occur in any given year, according to the National Weather Service.

A 10-year flood has a 10% chance of occurring in any given year, a 100-year flood has a 1% chance and a 500-year flood has a 0.2% chance. It should be noted that a 100-year flood doesn’t just happen once every 100 years — it has an equal chance of occurring every year, regardless of past events.

Rigos said his department puts work into mitigating floods all year, but especially from fall to spring. North Bend Public Works has a facility with thousands of sandbags available to the team and the community if needed. The department uses its vactor truck, which has a powerful vacuum, to clean out sewers or power wash culverts to break up debris and maintain water flow. The city also has more than 50 miles of storm drainage pipes and several thousand catch basins to collect stormwater.

“There’s a lot of potential property that could be damaged in a flood scenario,” Rigos said. “We have to take it seriously as a city.”

North Bend recommends residents take flood mitigation seriously. Recently, North Bend Mayor Mary Miller declared November “Flood Awareness Month,” encouraging residents to join her in learning how to be prepared for and reduce the risk of flooding.

According to North Bend’s 2024 flood newsletter, residents can take measures like retrofitting, grading a yard and correcting drainage problems. In an emergency, they can move furniture and put down sandbags. Residents can also elevate their homes, and the city offers to help with the grant process to do so.

“There are things you can do to reduce your risk, chief among them is just making sure that the normal drainage around your house isn’t blocked,” said Elizabeth Gildersleeve, an agent at Kevin Hauglie Agency in Fall City.

Flood insurance

The next thing residents can do is invest in flood insurance. Properties in a 100-year floodplain have a 26% chance of experiencing a 100-year flood during the life of a 30-year mortgage, and just 1 inch of flood water can cause up to $25,000 in damage, according to the Federal Emergency Management Agency (FEMA).

Rigos said he thinks anyone with property within a couple of feet of elevation from the 100-year floodplain should have flood insurance. That elevation, known as base flood elevation, differs depending on location and can be checked by searching an address in FEMA’s National Flood Hazard Layer Viewer.

Property insurance policies do not come with flood coverage, but many homeowners, renters and businesses in the Valley can get flood insurance because their cities participate in the National Flood Insurance Program managed by FEMA.

Last year, the National Flood Insurance Program finished implementing a new model for flood insurance pricing in an effort to make rates more equitable, Gildersleeve said. Insurance rates are now based on a home’s unique flood risk. The program considers more flood variables, like frequency, flood type and distance to the water source, as well as the specifics of the home itself.

“It used to be you could, like, ask your neighbor, ‘Hey, what are you paying for flood insurance?’ and your numbers should be pretty similar,” Gildersleeve said. “That just isn’t the case anymore, unless it’s an identical house.”

The new program also includes a Community Rating System, which can provide residents with a discount on flood insurance depending on the city’s flood mitigation efforts. Residents in North Bend can get 25% off of flood insurance because of the city’s extensive flood management plan.

Residents can also get mitigation credits on their policies by providing an elevation certificate, Gildersleeve said. Elevation certificates show a building’s location, specific elevation information and flood zone. Policyholders can hire a licensed surveyor to come to their property and certify its elevation information, according to FEMA.

Elevation certificates are also helpful for residents themselves, Gildersleeve said, because they give an idea of where flood water would end up in the property. With that information, she said, people can move some furniture and prepare their homes before the flood arrives.

As flood season sets in, it’s important for people to contact their agents as soon as possible, Gildersleeve said, since most flood insurance policies have a 30-day waiting period before they set in.

“We hope you never have to live through a flood claim,” Gildersleeve said.

Check city websites or contact public works for more details on an individual city’s flood plan.