When flooding is in the forecast
Climate change makes floods more frequent and dangerous, but here’s how to prepare
Flooding is a serious problem in Washington. Fall and winter rains often fill rivers. In spring, melting snowpack adds to the threat from rainstorms. And coastal regions often experience flooding at extremely high tides.
Climate change will make all these problems worse. But we can do something about it.
How Climate Change Affects Flooding
If you pay attention to Washington weather, you’ll probably hear the term “atmospheric river.” It’s when warm, moist air flows up from the tropics, often over Washington, bringing storms that last for days. The U.S. Global Change Research Program says that “they often transport as much water as the Amazon River.” Atmospheric rivers contribute up to 40 percent of annual snowpack on the West Coast.
These atmospheric rivers significantly affect Washington’s precipitation and water supply. That’s why it’s so important to understand how they’re connected to climate change. Studies show atmospheric rivers along the West Coast will become more frequent and intense because of climate change.
As heavier storms fall more often on Washington state, the likelihood of flooding increases.
Construction plays a part in flooding, too. Areas built with impermeable surfaces such as roads, parking lots, and buildings increase stormwater runoff into rivers and streams. The additional water can’t get absorbed into the ground like it does in vegetative areas and makes flooding more dangerous and destructive.
Floodplain planning, including the use of permeable surfaces, can reduce the threat from floods in developed areas.
On the coasts, as polar and glacier ice melt, the height of tides will increase. And as oceans warm, the water will also expand. The increased water levels will threaten people living along the coast by making high tides even higher.
What We Can Do
Floods are the most common and widespread of all natural disasters. Here are some tips to consider if you live in an area where floods occur.
Before a flood:
- Plan for evacuation, including where you are going to go, your mode of transportation, and the route you will follow. Have an alternate route in case flooding blocks one.
- Buy flood insurance.
- Keep all insurance policies and a list of valuable items in a safe place.
- Take photos or a videotape of the valuables you keep in your home.
- Have a transportation plan. Know how your local transit agency responds to floods. Check if there are social services to provide transportation you might need. And keep your vehicle charged or full of gas.
- Learn how to treat water to make it potable. We also offer advice on treating water during an emergency. Get the supplies you will need if you have a well, and learn how to do post-flood decontamination.
- Prepare your home for a flood. Check with your local building department or office of emergency management to learn if home or landscape changes can help.
During a flood:
- Don’t try to cross flooded areas. Water can be deeper than it appears, and water levels rise quickly. Follow official emergency evacuation routes. If your vehicle stalls in floodwater, get out fast and move to higher ground.
- Stay away from moving water. Moving water 6 inches deep can sweep you off your feet. Just 2 feet of water can easily sweep cars away.
- Listen to your radio or television for reports of flood danger. Follow social media accounts for the National Weather Service or your local news stations.
- Stay away from flooded areas unless authorities ask for volunteers.
- Stay away from downed power lines.
- If your home floods, turn the utilities off until emergency officials tell you it’s safe to turn them on. Don’t pump water from your home until the floodwaters recede. Avoid weakened floors, walls, and rooftops.
- Wash your hands frequently with soap and clean water if you touch floodwaters.
After a flood:
- Wear gloves and boots when cleaning up.
- Open all doors and windows. Use fans to air out wet areas to prevent mold or mildew. If you have a basement, we have some tips on cleaning it after a flood.
- Remove dirt and mud from walls, counters and hard-surfaced floors with soap and water. Disinfect by wiping surfaces with a solution of one cup bleach per gallon of water.
- Wash all clothes and linens in hot water.
- Discard mattresses and stuffed furniture. Cleaning them will not be enough.
- Throw away any food that contacted the floodwater. Canned food is all right, but thoroughly wash the can before opening.
- If your well floods, your tap water is probably unsafe for drinking, cooking, food preparation, washing dishes, or brushing teeth. If you have public water, the health department will let you know — through radio, television, and social media — if your water is not safe. Until you know your water is safe, only use bottled water, boiled water, or disinfected water.
- Do not use your septic system when water is standing on the ground around it. The ground below will not absorb water from sinks or toilets. When the soil dries, it is probably safe to again use your septic system. To be sure, contact your local health department. We offer tips on toilet use during an emergency. The EPA also has advice for septic system owners on what to do after a flood.
- As floodwaters recede, look out for weakened or collapsed road surfaces or sidewalks.
Learn more about climate change and what you can do to fight it on our website.
More Information
Information in this blog changes rapidly. Sign up to be notified whenever we post new articles. For more information from the Washington State Department of Health, visit doh.wa.gov.
Questions about COVID-19? Visit our COVID-19 website to learn more about vaccines and booster doses, testing, WA Notify, and more. You can also contact the Department of Health call center at 1–800–525–0127 and press # from 6 a.m. to 10 p.m. Monday, and 6 a.m. to 6 p.m. Tuesday — Sunday and observed state holidays. Language assistance is available.
