Guide
The same muddy back yard can have two very different causes. One can be fixed on the lot. The other belongs to the creek, the city and, often, a flood policy.
Updated November 5, 2026
Watch where the water comes from. If rain falls on your lot and its neighbors and collects in a low spot, it is a drainage problem that grading, basins or drains can fix. If water rises out of a creek, channel or the Trinity and spreads across the yard, it is a floodplain problem that no yard drain can stop. Rein Irving Drainage Company works on the first kind.
| Clue | Points to a lot drainage problem | Points to a floodplain problem |
|---|---|---|
| Where water enters | From the roof, the lawn, a neighbor’s lot or the street | From the direction of a creek, channel or river |
| When it peaks | During or just after the heaviest rain | Hours later, as the channel rises from rain upstream |
| How it leaves | Sits in a low spot and soaks in slowly | Recedes as the channel drops, often all at once |
| What it leaves behind | Puddles, soft ground, bare patches | A debris line, silt or trash carried in from the channel |
| Who else is affected | Mostly your lot, maybe one neighbor | A whole row of houses along the same creek |
Photos and the time of each one, taken during a storm, settle most cases. A video showing water flowing in from the creek side is better than any description.
FEMA publishes Flood Insurance Rate Maps showing the regulatory floodplain, including the 1% annual chance floodplain. You can look an address up on FEMA’s Flood Map Service Center. In Dallas County, the appraisal district map also has a FEMA flood-zone layer, which is often the quicker way to see a specific lot. Dallas’s own zoning map shows it too.
Two cautions. A map line is not a wall: lots just outside it can still flood, and older maps can miss newer development upstream. And a lot partly inside the line is treated as in it for any earthwork on that part.
Low ground near creeks has its own soils. The USDA soil survey maps Ovan clay, frequently flooded, at a north Irving sample point, and Frio silty clay, frequently flooded, at a south Irving point and in north Grand Prairie. “Frequently flooded” is the survey’s own flood class for those soils. These are sample points, not every lot, but if a yard sits on that kind of ground, two things follow: water drains slowly through the clay, and any outlet nearby may sit higher than the yard when the creek is up.
Every gravity drain depends on a lower outlet. When a creek or the storm system is full, that outlet is under water and the drain backs up. A sump pump can lift rain that collects on a lot to a higher outlet, but it cannot pump down a rising creek. Raising the yard with fill is not a simple fix either: in a mapped floodplain, fill can push water onto others, and cities review it. In Dallas, earthwork within the 1% annual chance floodplain is reviewed before construction is permitted.
What drainage can still do on a floodplain lot:
Creeks and major channels are public drainage, and cities manage them.
Many creekside lots have both problems: they flood from the channel a few times in a decade and stay soggy after every ordinary rain. The ordinary wetness is usually a yard drainage job. The flooding is a matter for flood insurance and the city. The insurance guide explains why the two are treated so differently.
Look the lot up on the FEMA map, then take photos during the next storm showing where water enters. If it comes from the lot, the roof or the street, the step-by-step guide explains the fix, or send the photos to us.
It is the area FEMA maps as having a 1 in 100 chance of flooding in any given year, often called the 100-year floodplain. Over a 30-year mortgage, that adds up to a meaningful chance of at least one flood.
Not without approval. Fill in a mapped floodplain can push water onto other properties, so cities review it. In Dallas, earthwork within the 1% annual chance floodplain is reviewed before construction is permitted.
Because its outlet is lower than the water in the creek or storm system. Water cannot flow downhill into a channel that is already full, so it backs up the pipe until the creek drops.
Send a photo during the storm and tell us how close the nearest creek or channel is.
