Residents along the river flats have spent years watching water arrive where the maps say it should not. In storms rated as ordinary, driveways turn to shallow ponds and basements take on inches. The maps that govern their insurance and their building permits, however, still describe the flats much as they did decades ago, and the gap between the paper and the puddles is starting to cost people money.
Why the maps lag reality
Flood mapping is expensive and slow, and the flats sit at the awkward intersection of a shifting river channel and gradually compacting soil. Neither factor is dramatic in any single year. Over a decade, though, they add up, and the cumulative change is exactly the kind that periodic official surveys tend to miss.
- Storm drains built for an older rainfall pattern back up more often
- Newer fill on upstream lots may be pushing runoff downhill faster
- Some homeowners cannot get accurate quotes because the base data is stale
We are not equipped to remap a floodplain, and we will not pretend otherwise. What we can do is collect what residents are seeing: dated photographs, high-water marks, and storm-by-storm notes. Assembled carefully, that record can make the case for an updated survey far better than any single anecdote.
If you live on the flats and have watched the water, we want your photographs and your dates. The paper trail starts with the people who live there.
Related: Environment & Land · the culvert nobody will own
Further reading: Land subsidence explained
