What The Winona Levee Protects, And What It Does Not
Downtown Winona sits behind roughly ten miles of sand levee and concrete floodwall, put in through the 1960s and 1980s. It works. When the Mississippi runs high, the water stays on the river side and the city stays dry. Prairie Island floods, Levee Road goes under, and downtown carries on.
That protection creates a false sense of safety. The levee stops river water from coming over the top. It does nothing about the water already underneath your house.
When the river climbs, the water table under the flats climbs with it. Five flood pumps push interior drainage back over the levee, and when the river is high those pumps are working against pressure. Storm sewers slow down. Groundwater rises against basement walls that were never built to hold it back. That is when downtown basements take water, and it is almost never from the direction homeowners expect.
River Stage And What It Means For Your Basement
The gauge that matters is the one at the Winona pumping station. Here is how the readings translate to risk on the flats.
| Gauge reading | What happens | Basement risk downtown |
|---|---|---|
| 9 feet | Levee Road goes under water | Low. Worth checking your sump and drain tile now. |
| 13 feet | Official flood stage at Winona | Rising. Groundwater pressure builds against foundation walls. |
| 20 feet | The concrete flood control wall engages | High. Interior drainage is slow and sump pumps run continuously. |
| 22 feet | Wall design height, with two feet of freeboard above | Severe. Sustained pumping and standing water in low basements. |
The record crest at Winona is 20.77 feet, set on 19 April 1965. Most homeowners who lose a basement downtown never see the river at all. They see two inches of water on a finished floor while the Mississippi sits calmly behind a wall six blocks away.
Older Downtown Housing Stock And Where Water Gets In
Much of the housing in Downtown Winona predates the levee by decades. That means limestone and rubble foundations, mortar joints that have been repointed more than once, floor drains tied into clay laterals, and basements finished at some point in the last forty years with framing set straight against masonry.
Those buildings fail in predictable places. Water tracks in at the cove joint where the wall meets the slab. It wicks up through unsealed stone. It backs up through the floor drain when the sanitary line surcharges. In a finished basement, all three routes put water behind drywall where nobody sees it until the smell arrives.
We open those cavities. Moisture behind a finished wall does not dry on its own, and a fan pointed at the carpet does nothing for the bottom sixteen inches of insulation that is already saturated.
How We Handle A Downtown Winona Water Loss
First call is triage. We ask what the water is, where it came from and how long it has been sitting, because a clean supply line failure and a sanitary backup are two different jobs with two different safety protocols.
On site, the contractor maps moisture before touching anything. Thermal imaging and pin meters find the wet edge, which in a stone basement is usually further out than the visible water line suggests. That map decides what gets removed and what gets dried in place.
Extraction runs first, then containment, then air movers and dehumidifiers sized to the actual cubic footage. Readings get logged daily against a dry standard taken from an unaffected part of the building. Equipment comes out when the numbers say so, not when the calendar says so.
If the source was a sanitary backup, the affected materials come out rather than getting dried, and the space is cleaned and treated before anything is rebuilt. For that work see our sewage backup cleanup page.
Call (507) 698-9249 and we will route you to a restoration contractor working downtown.
What To Do Before The Contractor Arrives
Shut the water off at the main first. In most downtown houses that valve is on the wall facing the street, often behind the stairs. If the water is coming up through a floor drain rather than out of a pipe, the main will not help and you should skip to the next step.
Kill power to the affected circuits at the panel. Standing water and basement outlets are a bad combination, and in older downtown wiring the basement is frequently on the same circuit as something upstairs.
Then stop. Do not run a shop vac through a sanitary backup, and do not pull up carpet you intend to claim on before it has been photographed. Take pictures of everything, including the water line on the wall, and leave the rest to the crew.
