A creek runs under the west side, inside a pipe
Allen Creek was buried in a drain last century. The city kept developing west above it, and the runoff routed into that pipe kept rising until the pipe was over capacity. The City of Ann Arbor and the Huron River Watershed Council both describe the result plainly: in a large storm the storm sewer cannot take everything at once, and water surfaces in the streets above the old creek line. Homeowners in the creekshed are frequently unaware they live on top of a creek at all.
What it means for the job. A house can flood on a storm that leaves a house a mile away dry, and the pattern repeats in the same blocks. That is a drainage-capacity loss, not a plumbing failure, and it is the reason a repeat is likely unless something changes at the property.

