Where do floodwaters go when they recede, and what do they leave behind?
MINNEAPOLIS -- The Mississippi River is getting mightier in downtown St. Paul and Hastings, but it is receding in towns to the north. Levels in other river cities are also dropping for now.
That left us wondering: When floodwater recedes, where does it go, and what does it leave behind? Good Question.
If you thought only one Twin Cities lake carried the name Harriet, then you haven't visited St. Paul recently.
"We live in the condos across the river and basically have been seeing this new lake form over here at Harriet Island, which I've been calling Harriet Island Lake," one resident said.
But where does that water go?
"I'd assume most of it heads south to the southern states, maybe New Orleans," one resident said. "St. Louis?"
For the most part, that's right.
"Most of the water is going to flow back into the river system and downstream, ultimately to the ocean," National Weather Service hydrologist Shawn DeVinny said.
Whether it's a lake, stream, or river, he says floodwater mainly returns to its original source. Some of it does soak back into the ground as well.
"We had the severe drought leading into the winter and so a lot of water did soak into the ground," DeVinny said.
And then, of course, some of it evaporates and goes back into the atmosphere. Dry and sunny days can speed up the floodwater recession in that regard.
"Conversely, if it's cool and cloudy and humidity's higher, it's going to slow down our evaporation rate, so it definitely plays a role," DeVinny said.
And that water movement can leave the landscape somewhat altered.
"It's gonna need some time, significant time to dry out, and it can leave behind debris, lots of sediment," DeVinny said.
And, unfortunately, also some garbage.
Minnesota functions somewhat as a barometer for what the towns and cities further south can expect in the coming days and weeks.
"I think about places like Davenport, Iowa along the Mississippi River, and they didn't have a ton of snow and rain this winter kind of like we did, but they have this big flood wave coming down the main stem river," DeVinny said. "So they're watching what we're doing up here and how much water we're going to be sending, and they're watching closely."
DeVinny says river towns remain vulnerable even as the water recedes. If the ground doesn't dry out and more rainfall comes, another crest is possible for some areas.
