News

Low risk of major flooding along Cedar, Iowa rivers

Flooding likely on Mississippi River because of snowpack in Minnesota and Wisconsin, National Weather Service forecasts

Work continues on the flood wall along the Cedar River near the Quaker Oats plant in Cedar Rapids on Thursday, Dec. 26,
Work continues on the flood wall along the Cedar River near the Quaker Oats plant in Cedar Rapids on Thursday, Dec. 26, 2019. The project started in 2018 and is expected to be finished in 2021. Earlier this month, the city cleared a hurdle in agreeing with Union Pacific Railroad Co., whose tracks intersect the flood wall here, on a $3.1 million agreement to allow construction of a railroad floodgate in 2021. (Liz Martin/The Gazette)

CEDAR RAPIDS — There’s a slightly elevated risk of spring flooding on the Cedar and Iowa rivers, but nothing like what’s expected on the Mississippi River.

The Cedar River at Cedar Rapids has a 9 percent likelihood of reaching major flood stage of 16 feet this spring, compared with the 7 percent historical average, the National Weather Service reported Thursday. The river is 31 percent likely to reach minor flood stage at Cedar Rapids, but the historical risk of that is 26 percent, so not a huge increase.

The risks of major spring flooding on the Iowa River also are relatively low.

The Iowa River at Iowa City historically has a less than 5 percent chance of reaching its major flood stage of 26 feet and that’s the likelihood for this spring as well, the Weather Service reported. The likelihood of minor flooding in Iowa City this spring actually is lower than the historical risk.

“Right now we don’t have a whole lot of snow on the ground in Iowa and in the Cedar River watershed,” said Jessica Brooks, a hydrologist with the Weather Service Quad Cities. “The real threat for flooding will rely on getting some heavy spring rains, which is harder to quantify.”

Thursday’s forecast was the first of the spring season. The service plans to issue an updated flood forecast Feb. 27 and March 12.

The Weather Service’s Quad Cities Hydrologic Service Area, which covers part of Eastern Iowa, northwest and west central Illinois and extreme northeast Missouri, predicts 2020 could be a repeat of 2019 on the Mississippi River, which rose to record levels last year and inundated many communities.

The likelihood of the Mississippi River at Dubuque reaching major flood stage of 21.5 feet is 91 percent, compared to the 13 percent historical average. At Rock Island, the risk of reaching major flood stage of 18 feet is greater than 95 percent, compared to 22 percent historically.

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Brooks said the Mississippi River forecast shows higher risks of spring flooding because of the vast snowpack in Minnesota and Wisconsin, where soils already are saturated.

“Almost all of that snow, when it melts, will be released into the rivers and into the Mississippi River,” she said. “We have higher confidence right now that we’re going to have flooding on the Mississippi because of the snow itself. If we get into a wet pattern this risk could increase.”

In recent years, Cedar Rapids has put projects in place to reduce the effects of flooding.

They include the Sinclair levee project — a half-mile levee and flood wall, pump station and 4.4-acre water retention basin completed in 2017 — and storm sewer upgrades.

This year, the city plans to finish a $17 million project to build a flood wall and pump stations near Quaker Oats. The wall, which will be up to 18 feet in some places, was designed to offer protection up to the levels of 2008, when the Cedar River flooded 10 square miles of the city.

Cedar Rapids is doing design work for the flood system through downtown and the Eighth Avenue Bridge replacement.

Comments: (319) 339-3157; erin.jordan@thegazette.com

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