Storm & Flood Damage Recovery in Cedar Rapids, IA

That is normal and it is the most important thing to understand about flood risk in this valley. The Cedar drains a very large agricultural basin upstream, and what happens two counties away determines the stage here. Local rainfall is a poor predictor. Following the upstream gauge readings rather than the local forecast gives far more warning, and in a large event that difference is measured in days rather than hours.

It changes what to expect from it. Loess takes water in readily, which is good, and then holds it and loses strength, which is not. Backfill against a foundation can settle after a prolonged wet period, opening a gap at the wall that channels the next rain straight down to the footing. Checking and refilling settled backfill after a wet year is worth doing here specifically, more than in a place with stable clay.

Safer, but the flood level is not the only mechanism. In a large river event the groundwater across the whole terrace rises with the river, and basements above the surface flood line still take water through the floor and wall joint from below. Sump systems in that condition run continuously and can be overwhelmed. Elevation relative to the river answers the surface question and leaves the groundwater one open.