Walnut Creek is a tributary of the Raccoon River that runs through Polk and Dallas counties. Its floods tend to come in short, high peaks that pass quickly, and the water leaves moisture behind. After a creek flood, check the lowest entry points, measure the walls and record what is seen before cleanup. Ankeny Water Damage Restoration takes calls for this work in Ankeny and the metro at any hour.
Key takeaways
- Walnut Creek is a tributary of the Raccoon River, and it runs through Polk and Dallas counties.
- A 1979 environmental report described the creek's flooding as recurring, with high peaks that pass quickly.
- The 1986 flood is the largest on record at the Walnut Creek gauge at Des Moines.
- Creek water usually enters a home at a low point such as a walkout door, a window well or a floor drain.
- The water can leave, but the moisture it carried into walls and floors can stay for much longer.
How does Walnut Creek flood compared with a river flood?
A creek rises and falls faster than a large river, and its flood water tends to arrive in short, high peaks. The water may cover a low area for a few hours rather than many days. The moisture it leaves in walls and floors, however, is the same kind of problem, and it needs the same measured drying.
Walnut Creek is a tributary of the Raccoon River. It runs through Polk and Dallas counties, and Polk County is where Ankeny sits. A 1979 environmental report described the creek's flooding as recurring, with high peaks that pass quickly. That is the pattern to expect: a rise that is sudden, a peak that is high and a drop that comes soon after.
The short peak can fool a homeowner. Once the water has gone back into its channel, the house may look almost normal. The damage, however, is often inside the walls and under the floor, where the water soaked in during the peak and stayed after the surface dried.
How does creek water get into a basement or a lower room?
Creek water finds the lowest openings of a building. A walkout door set low to the ground, a window well that fills, a floor drain that backs up and a crack in a foundation wall are the common routes. The first step after a creek flood is to find which of these took the water in.
A walkout door is one of the most direct routes, because it can sit at or below the level of the water running across the yard. A window well that overflows drops water straight down to the basement window and then onto the wall below it. A floor drain can back up when the storm and sewer lines are full, which is a different and more contaminated route.
Foundation cracks and joints can let water through when the soil around the wall is saturated. The crew checks each opening, looks at the grade beside the house and notes which entries were wet. The route decides where the moisture is most likely to be, and it tells the crew where to measure first.
- Walkout doors set low to the ground
- Window wells that fill and overflow
- Floor drains that back up when lines are full
- Cracks and joints in the foundation wall
- Grade that slopes toward the foundation at a corner
What should I check once the creek water drops?
Look at the silt line on the walls, the damp spots at the baseboard, the window wells and the walkout door. Smell the room for mustiness, and press gently on the bottom of the drywall to check for softness. A moisture reading is the reliable check for what you cannot see, and it is worth taking even when the floor looks dry.
Start outside. Look at where the water flowed toward the house and which window wells filled. Note the silt, leaves and debris left on the ground and in the wells, because they show the path the water took. Then go inside, starting at the lowest point, and work up the walls.
A flashlight held low against the wall can show a stain or a bloom of white mineral deposit that marks the waterline. Press gently on the bottom edge of drywall. Soft or crumbling board has taken water and will not dry back to its original strength. Do not poke holes in the wall to test it.
| Where to look | What it can show | What to do next |
|---|---|---|
| Window wells and walkout door | The entry route and the silt that came with the water | Photograph and note the route; keep the debris for the record |
| Lowest wall at the baseboard | The height of the waterline and any wet zone | Take a moisture reading and note the height |
| Floor and floor drain | Silt, staining and whether the drain is holding water | Clear the drain only after the power is confirmed safe |
| Stored items and shelving | Water marks on the bottoms and softened cardboard | Move items out and photograph each before removal |
| Sump pit | Whether it is still filling or has overflowed | Check that the pump is running and the discharge is clear |
| Smell and dampness | Moisture still held in the wall or floor | Ask for a reading; do not seal the room |
What should I photograph after creek flooding?
Photograph the outside where the water came in, the window wells and the walkout door, the waterline on each wall, the damage to each finish and every item removed. Take wide and close pictures, and note the date and time. These photographs are the core of the record an insurer usually asks for.
Take the outside photographs first, while the water is still visible and before any silt has been disturbed. Show the slope of the ground, the window well and the walkout door. A photograph of the route is more useful than a photograph of the damage alone.
Inside, photograph each room from the same corner so the set is easy to compare. Take a close picture of the waterline with a ruler or a known object beside it if one is at hand, and photograph each item before it is moved. Keep the original files with their date information.
Why does the moisture stay after the creek has gone down?
Water soaks into the soil, the wall cavity, the insulation and the subfloor during a creek peak. Those materials release moisture slowly, and the ground outside can stay wet long after the creek is back in its channel. The moisture keeps working on the structure until it is measured and dried.
A wall that looks dry on the surface can hold water in the cavity behind the drywall. Insulation holds moisture and releases it slowly. The subfloor and the bottom plates of the walls can stay wet for longer than the floor above them looks wet.
The ground outside matters as well. Soil around the foundation can stay saturated after the creek has dropped, and it can keep feeding moisture into a basement or crawl space. The crew measures the ground at the foundation as part of the drying plan.
What does the cleanup look like after a creek flood?
The cleanup starts with safety and the removal of standing water, followed by the removal of silt and debris and the opening of wet materials at the readings. Drying equipment is then set and read on each visit, until the structure reaches the dry level set at the start. The record is kept throughout.
Standing water is pumped or extracted at a measured pace, with the discharge route set so the water does not return to the house. Silt is removed while it is still damp, because dried silt is hard to clean and holds moisture against the floor.
Wet drywall and insulation are removed where readings show the moisture has reached the cavity. Air movers and dehumidifiers are then placed and read on each visit. Equipment comes out when the readings show the structure is dry, not when the room looks better.
What can I do to lower the risk next time?
Keep window wells clear, check that the grade slopes away from the house, make sure the sump and its discharge are working, and clear floor drains before a storm. A qualified contractor can advise on the grade, the drains and any repair to the foundation.
Window wells with a cover or a drain at the bottom keep the opening clear during a storm. Downspouts should carry roof water well away from the foundation. A sump pump should be checked before the wet season, and its discharge line should not end where water can flow back toward the house.
Grading changes and foundation repairs are for a qualified contractor. The crew's record of the water path can be shared with that contractor, so the repair is planned around where the water actually went.
Frequently asked questions
Is Walnut Creek the same as the Raccoon River?
No. Walnut Creek is a tributary of the Raccoon River, and it runs through Polk and Dallas counties. A creek flood and a river flood can both reach the metro, but they arrive in different ways and at different speeds.
Why does the creek flood only last a few hours, but the basement stays damp for days?
A short peak can leave water in the soil, the wall cavity and the subfloor. Those materials release moisture slowly, so the basement can stay damp after the water has gone. A reading shows whether the moisture is still there.
Should I seal the window well after the water is gone?
Not until the crew has seen it and the source is documented. Sealing hides the route and can trap moisture that is still coming in. Photograph the window well, and ask the crew about covers or drains for the future.
Can I clean the silt off the floor myself?
Silt can be cleared while it is damp, but it should be handled with gloves and boots, because creek water can carry debris and contaminants. Dried silt is hard to clean and can keep the floor damp, so it is better removed during the cleanup.
Will the crew check the sump pump?
Yes, when the crew is on site for a creek call it checks the pump, the float, the check valve and the discharge line, and it reports what it finds. A repair is made by a qualified contractor.
Does my insurance cover a creek flood?
That depends on the policy and on whether flood coverage was added. Many standard homeowner policies treat flood water differently from sudden water sources. The insurer decides the claim, and the crew's photographs and readings are the facts it will look at.
Sources
This guide is general information for Polk County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.