Spring snowmelt in Spokane builds slowly. Melt runs off saturated ground, collects against the foundation and seeps through walls, joints and window wells. The Spokane County Flood Insurance Study describes spring snowmelt floods as one of the county's two main flood types, and the water often shows in a basement after the street is clear.
Key takeaways
- Snowmelt is a slow flood that saturates the ground around the house, so water can keep arriving for days after the snow is gone.
- The Spokane County Flood Insurance Study names spring snowmelt floods as one of the two main flood types in the county.
- Water often enters through the foundation wall, the floor joint, a window well or a bulkhead door rather than through the floor drain.
- A sump pump that runs for long stretches during a thaw should be checked, because it may not be keeping pace.
- Clearing snow and debris away from the foundation and the window wells before a thaw reduces the water that reaches the wall.
How does snowmelt get into a basement?
Melt water soaks into the ground and keeps the soil saturated, and the pressure pushes water through foundation walls, cold joints, window wells and the seam between the floor and the wall. The water moves toward the lowest point it can reach.
A deep snowpack holds a large volume of water. When warm weather arrives, the melt runs off the surface, into the soil and toward the foundation. Where the soil is clay or packed fill, the water drains slowly and builds up against the walls for longer.
The water does not always come in as a pool. It often appears as a damp line on the wall, a patch of wet concrete at the corner, or a thin film of water along the floor edge. That is the pattern to look for after a thaw.
What does the county record say about snowmelt?
The Spokane County Flood Insurance Study describes spring snowmelt floods as one of the two main flood types for the county. The study also describes winter rain-on-snow events as a separate type, and it notes that Coeur d'Alene Lake reduces peak flows on the lower river.
A flood type describes how the water arrives. Snowmelt is a gradual rise that can last a long time, while a rain-on-snow event adds rain to the melt and produces a faster, larger runoff. Both can put water against a house, so a homeowner in the flood-prone reach should know which one has happened.
The Spokane County record includes large historic floods, and the study names December 1933 as the largest with water-surface data and a May 1894 flood as the highest on record since gaging began. The study does not tie each of those floods to a single cause, so the record is best read as the range the river has reached.
How does the thaw show up inside a house?
The first signs are often a damp corner, a stain along the bottom of the wall, a smell of wet earth and a sump that runs more than usual. Water that appears after a warm spell, when the ground is soft, usually points to melt.
A basement wall that is wet only in one corner points to a water path at that corner, perhaps a window well or a crack in the foundation. A wall that is wet along its whole length points to saturated soil against the foundation.
The smell is a signal as well. Earthy or musty odors that appear after a thaw suggest that the framing and the cavity are holding moisture, and that the drying should be checked even if the floor looks dry.
What should I check before the thaw?
Clear snow and ice away from the foundation and the window wells so melt runs away from the house. Check that gutters and downspouts discharge well away from the walls. Test the sump pump by pouring water into the basin and watching the discharge.
Snow piled against the house holds moisture against the foundation and melts there. Pull it back far enough that the melt runs away from the wall, and keep clear of icy slopes and roofs. Clear the window wells and the bulkhead door so water can drain out of them.
Test the sump before the warm spell. Pour water into the basin, check that the pump starts, and make sure the discharge line runs well away from the house. A sump that cannot keep pace is a sign that the water path needs attention before the thaw.
When does a thaw need a professional visit?
Call for a visit when water is standing on the floor, when the sump cannot keep up, when the water has reached the electrical panel or an appliance, or when a smell persists after the water has gone. A visit at that point records the water and the readings before the damage grows.
Standing water near electrical equipment is an emergency. The line is answered at any hour, and a local technician is sent as soon as one is free. No arrival time is promised on the call.
A damp wall that is not standing in water is still worth a reading. A technician can measure the moisture in the framing and tell you whether drying is needed, which can prevent growth in the cavity later.
Why do snowmelt events come back?
They come back when the ground saturates again and the water has the same route to the foundation. The cleanup removes the water that is in now, but the drainage, the grading and the window wells decide what the next thaw does.
The county hazard mitigation plan lists flood declarations in 1956 and 1957, and the February 1996 flood reached the county. Repeated declarations show that high water in the county comes back, so a property in a flood-prone reach should plan for the next thaw.
A grading contractor or a drainage specialist can review the slope of the lot and the path of the water. A cleanup crew records the path and the readings, which gives that specialist a starting point.
What happens to the lower wall after melt water?
Wallboard and insulation that have taken water from the outside may need to be cut out and dried. The crew reads the wall at several heights and sets the cut at the level the moisture requires.
A wall that is wet from the outside often holds water in the bottom plate and in the insulation. Drying the cavity without cutting the wallboard is possible for a lightly damp wall, but a soaked wall usually needs an opening.
The cut is planned on the readings and recorded for the insurer. Replacement and finishing are separate work for a contractor you choose.
What should I write down during a thaw?
Note the date each water sign appeared, the weather before and during it, where the water showed and how deep it was. That record shows whether the water comes back in the same place each thaw, which helps the next visit.
Photograph the wall and the floor at the same spot each time, with a reference such as a measuring tape. A set of dated photographs is the simplest record of a recurring water path.
Keep the record with the house papers, along with the crew's readings and any insurance correspondence. It is the single most useful thing to show a contractor or an insurer about a snowmelt problem.
What if my basement has a finished room?
A finished room takes water differently from an unfinished one. Carpet, pad, drywall, trim and furniture hold water and hide moisture, so the crew reads the wall above the visible line and checks the floor under the finish.
A finished basement needs more survey time than a storage basement, because the moisture is often behind a wall or under carpet. The crew explains which finishes must be removed and which can stay in place while they dry.
Ask the crew to show you the readings on the finished wall before any cut is made. A reading you can see is the simplest way to understand why a section is being removed and another is being kept.
How do I plan for next year's thaw?
Plan the thaw as a checklist: clear the snow from the foundation, clear the window wells, test the sump, check the grading and note where water appeared last time. A written plan from the last event makes the next thaw simpler to manage.
Keep the photographs and readings from the last event with the thaw checklist. Compare the water line and the wet spots with the new readings to see whether the water path has changed.
If the same spot takes water every year, a grading contractor or a drainage specialist can review the path, and the record from the cleanup gives that specialist something concrete to work from.
Frequently asked questions
Why does my basement get wet after the snow has gone?
The ground stays saturated for days after the surface looks dry, and water keeps moving toward the foundation. A basement can wet up late for that reason, even when the street and the yard look clear.
Should I run the sump all through the thaw?
Run it when water is rising, and keep the discharge line clear of the house. If the pump cannot keep pace, note that and have a plumber look at it before the next thaw.
Is snowmelt covered by a homeowner's policy?
That depends on the policy and on how the water arrived. Outside water and flooding are often treated differently from water that enters suddenly from inside the home. Ask your insurer directly, and keep the crew's record.
How can I tell if the water is melt or a pipe?
Melt tends to come and go with the weather and to appear at the wall or a window well. A pipe leak is steady, usually clean and starts at a fixture. A technician checks both on the first visit.
Should I cover the window wells?
A cover can keep snow and debris out, but it can also trap water if the well cannot drain. Make sure the well drains before you cover it, and ask a contractor if the drainage is poor.
Does a thaw always mean the basement will flood?
No. A thaw brings water to the ground around the house, and whether it reaches the basement depends on the grade, the drainage, the walls and the window wells. Checking those before the thaw is the way to tell whether the house is at risk this season.
Sources
- City of Spokane, Spokane County Flood Insurance Study
- National Weather Service, Advanced Hydrologic Prediction Service, Spokane gage
This guide is general information for Spokane County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.