As Chippewa Valley residents dig out from yet another snowstorm this weekend, local officials are looking ahead to what happens when it all melts.
Though it might seem hard to imagine at this point, the towering snow banks lining streets and driveways soon will turn to water. And with that much-anticipated rite of spring will come the risk of flooding.
The National Weather Service is predicting a higher-than-usual risk of flooding this spring for much of the Upper Midwest, including west-central Wisconsin, as a result of the winter’s record-setting snowfall. Eau Claire received 53.7 inches of snow in February, shattering a 90-year-old record for monthly snowfall in what through Friday had been the third-snowiest winter in recorded history.
“We’re taking this pretty seriously,” said Tyler Esh, emergency management coordinator for Eau Claire County. “With the historical snowfall levels after a fall that was wetter than normal and more precipitation in the forecast, a lot of factors are lining up to potentially make it a bad year for flooding.”
Local public works officials and emergency response personnel will meet Monday to go over flooding response plans and discuss the latest National Weather Service flooding outlook, which was released Thursday.
The agency’s analysis indicated the Chippewa River has a 30 percent chance of reaching major flood stage, or 778 feet above sea level, in downtown Eau Claire. That compares with the typical spring risk of less than 5 percent. It set the risk of reaching moderate flood stage (776 feet) at 34 percent, up from 7 percent normally, and the risk of minor flood stage (773 feet) at 62 percent, up from the usual 14 percent.
The forecast showed a 63 percent chance of minor flooding and a 26 percent chance of moderate flooding of the Eau Claire River near Fall Creek, both significantly higher than normal. However, the risk of major flooding on the Eau Claire River was set at the typical level of less than 5 percent.
Major flood stage risk was estimated at 50 percent or more all along the Mississippi River south of St. Paul.
“The amount of snow water equivalent in this snowpack is in the upper 10 percent of historical records over a widespread area ... leading to a high flood potential for many river basins,” states the Weather Service report, which recently increased the Chippewa Valley’s risk level.
“The bottom line is the flood potential has increased because of more snow — the storm expected this weekend and a chance of more snow in the middle of the week,” Weather Service meteorologist Tyler Hasenstein said. “That’s two more chances to add to the already high moisture content.”
A predicted 7 inches of snow this weekend in Eau Claire would bring the season total to 88.8 inches, or just a half inch short of the all-time record of 89.3 inches set in 1996-97.
Such warnings have local officials studying historical flood levels and putting in place response plans for expected new flooding, all while keeping an eye on the latest forecasts.
“We’re preparing for the worst and hoping for the best,” said Jeff Pippenger, community services director for the city of Eau Claire, who is designated as the city’s incident commander in the event of serious flooding.
As part of that approach, Pippenger ordered 30,000 sand bags Friday to add to the city’s just-in-case stockpile of 20,000.
The city estimates 32,000 sand bags would be needed in the event water rises high enough that the top of the dike along Forest Street would need to be reinforced to protect the adjacent neighborhood, which historically had many houses fill with floodwater in the springs before the city acquired 50 properties in the area after the so-called “Great Flood” of 1993.
City officials know from experience the impact of flooding when the Chippewa River reaches various levels.
Minor flood stage would lead to the closing of low-lying stretches of the Chippewa River State Trail and parts of the parking areas by Hobbs Ice Arena. Moderate flood stage means much of Owen Park would be covered in water nearly to First Avenue. Reaching major flood stage, which has happened only five times in the last 135 years, would result in water inundating First Avenue, the low side of Haymarket Plaza and the road leading to the city’s wastewater treatment plant.
All of the new construction downtown should stay dry even if major flood stage is reached because structures are now required to be built above the 100-year flood elevation of 781.8 feet above sea level, a high water mark that hasn’t been reached since the record flood of 1884, said city engineer David Solberg.
If water rises to a certain level, city crews will attempt to reduce the risk by inflating pneumatic plugs in storm sewer pipes to prevent river water from coming back into the drainage system, Pippenger said.
Eau Claire County Highway Commissioner Jon Johnson said officials are planning for worse-than-usual flooding this spring.
“We’re going to have a mess on our hands,” he predicted.
The latest Weather Service flooding outlook for Durand, a Pepin County community with a history of Chippewa River spring flooding, shows about a one in three chance of hitting major flood stage and a two in three chance of reaching moderate flood stage, both about five times the typical risk. The city has a 95 percent chance of having minor flooding.
Despite the elevated risk, Durand city administrator Scott Rasmussen said most residents are taking a been there, done that approach to the possibility of the river overflowing its banks in the downtown business district.
“It’s kind of business as usual at this point,” Rasmussen said. “People just don’t get too excited about it. It is what it is down here.”
Longtime Durand residents understand the inevitability that spring flooding likely will mean some streets along the river will have to close and businesses backed up to the river will get water in their basements and thus will have to get items that can’t get wet off the floor.
“At this point, nobody is really nervous,” Rasmussen said, noting that officials have no plans to deploy sand bags or take other extraordinary steps to protect property from rising water. “The plan is just to let it run its course and hope for the best. There’s nothing we can do about it is what it comes down to.”
In Eau Claire County, Esh said, residents can take some steps to lower their risk of suffering personal or property damage and the chance of dealing with flooded streets.
To reduce the probability of having neighborhood streets covered in water, he said, residents can help street crews by clearing the area around storm sewer drains, many of which remain covered by several feet of snow.
Esh also advised members of the public to get anything valuable off basement floors, sign up for emergency notifications through the county website and keep a vehicle full of gas and prepared to go on short notice in case of flash flooding.
The timing and severity of spring flooding will be largely dependent on how fast warming begins and how much precipitation is received during the snowmelt period.
“What we have to hope for is moderate temperatures during the day and below freezing temperatures at night,” Pippenger said.
Such an ideal scenario would reduce the flooding risk by bringing about a gradual thaw.
“A slow melt would make a lot of people happy even though I think city personnel are craving warm weather as much as anyone else,” Solberg said.
Significant rain during the snowmelt period would have the opposite effect, especially considering the existing snow covering the ground has a higher-than-usual moisture content and any additional snow accumulation in the spring often is the heavy, wet variety.
“If we get any major rainstorms or a sudden warm-up, it would skew our numbers significantly and could be a very dangerous event,” Esh said, adding that the highest-risk time period for flooding is projected to begin the last week of March and run through mid-March. “If we were to start melting snow soon, with frost still several feet deep, there’s nowhere for all the water to go.”