BY GABE LICHT
DELANO, MN Many factors play a role in the flooding of the South Fork of the Crow River in Delano.
Experts with the National Weather Service and local officials are evaluating those factors ahead of spring to determine the likelihood of flooding.
As it stands now, that likelihood is higher than average.
“We remain on track for a very active spring flood season, given that soil moisture content is very high and river levels remain well above historical normals for midwinter,” NWS hydrologist Craig Schmidt wrote in an email to a number of stakeholders throughout Minnesota. “Frost depth is encouraging so far, as it is shallower than normal, but the extent of flooding will be determined by temperatures and precipitation in February, March, and April.”
There was an elevated flood risk in 2019, as well, but the ideal conditions experienced that spring mild days with cold nights and three weeks of no snow or rain in March are far from guaranteed in 2020.
“The key point is that we are in a more vulnerable situation this year than last year at this time, but we had an ideal melt last spring, which kept flooding from being much worse than it was,” Schmidt wrote.
Even a “normal” amount of precipitation in the winter would bring an elevated risk for flooding in the spring, according to the outlook Schmidt sent to stakeholders.
“There is a ton of water in the system,” Delano City Administrator Phil Kern added. “All the backwater areas are high from heavy rains last fall. Everything is queued up for an elevated risk this spring.”
According to the NWS, the entire Upper Midwest received well above normal rain in the fall, mostly 150 to 200 percent of normal. That caused river levels throughout the region to remain very high. While the South Fork of the Crow River did not set any records, many other rivers did.
Precipitation from this point on will play a large role in flooding probability.
“Outlooks continue to favor near to above normal precipitation for the winter months,” according to the NWS outlook. “The indicators are fairly weak in the global pattern this winter (no strong El Niño or La Niña), so confidence is not particularly high this year. Temperatures will be fairly mild into early February, then potentially below normal the rest of the month.”
The lack of frost depth is the silver lining.
“There’s very little frost in the ground,” Kern said. “When the melt comes and spring comes, hopefully the time period in which the ground won’t absorb water will be much less than last year. That’s a big factor working in our favor.”
One factor that cannot be predicted is ice, as an ice jam caused the river to rise dramatically in 2019, prompting city crews to erect the temporary floodwall along River Street.
“We had an ice jam at the bridge and north of town that raised levels by 2 feet and stayed there for the better part of a week,” Kern said. “This year, we’re going to be susceptible to typical flooding, but we’ll also have to be aware of ice and the potential for a quick melt.”
Improvements have better equipped the city to handle potential flooding.
The temporary floodwall city crews can erect downtown is just one asset the city has in the fight against floodwater.
Now, through a partnership with Wright County, the city also has a permanent floodwall on County Road 17, north of Highway 12.
“It’s probably been the one area of town that’s caused us the most concern in recent years because the bank had been eroding away and was really weak,” Kern said. “We’ll no longer have to build a temporary levee across River Street like we had to last year and a number of years over the past 10 years . . . We are looking forward to dealing with floodwaters with that in place.”
There is another less visible improvement the city has made west of the American Legion on Highway 12.
“We replaced a storm sewer pipe that has allowed the river a back channel into town to the area across from the Legion,” Kern said. “When the river comes up, we can close the valve. Property owners on the west side of Highway 12 have dealt with water in their backyards quite regularly over the past few years because of a leaking storm water system that is now taken care of and will be able to handle that much better.”
With those improvements, the city is well-positioned to handle rising water.
“We’re more prepared than we’ve ever been, but we’re also cautious and aware that a major flood can have major impacts on the community,” Kern said.