Rains from tornado-spawning storms shrink area of Iowa's 4-year drought, but fail to bust it

Powerful storms that sparked tornadoes across Iowa last month brought rainfall that's helped move half the state out of drought, a new report shows.

About 50% of the state is experiencing either no drought or only abnormally dry conditions, with roughly an equal percentage experiencing moderate to extreme drought, according to the U.S. Drought Monitor, released Thursday. That’s a shift from January, when nearly 80% of the state was gripped in drought, and about 20% of the state experienced no drought or abnormally dry conditions.

While still investigating, experts say Iowa saw 41 tornadoes hit the state in April, including the string that damaged Iowa towns last week. The storms brought 1 to 3 inches of rain over large parts of Iowa in the past two weeks, with parts of southern and northwest Iowa getting 4 to 5 inches, said Kristy Carter, a meteorologist with the National Weather Service in Des Moines.

So, with ponds of water standing across the state, is Iowa still in the grip of the longest drought in 65 years? The short answer is yes.

“We’ve seen improvement over the last several weeks with rainfall that’s been extremely beneficial in terms of attempting to bust the drought,” said Justin Glisan, Iowa’s state climatologist. “But there are parts of the state that are not out of the drought.”

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Here’s what to know about drought and recent rains:

How can Iowa still be in a drought?

Parts of Iowa have been gripped by drought since July 2020. And it continues. Nearly 48% of Iowa still struggles with moderate to severe drought, and about 2% of Iowa — seven counties in northeast Iowa — is still in extreme drought, according to the Drought Monitor, which measured conditions through Tuesday. Rainfall since then will be captured in next week's report.

April brought an average of 4.5 inches of rain statewide, about an eighth to a half inch more than normal, Glisan said.

How much more rain does Iowa need?

“We’re chipping away at drought, but we’ve been very dry over an extended time,” Glisan said.

Several months of above average rainfall would help drought-stricken areas of Iowa recover, he said. Even if the Drought Monitor indicates the state has escaped drought, parts could easily get pulled back in, given that some areas are short 30 inches or more of rainfall.

“That’s almost a year's worth of precipitation,” Glisan said.

Is the rainfall we’ve seen helping to replenish subsoil moisture and groundwater?

Parts of Iowa have experienced long soaking rains that are penetrating the soil as well as hard rains that run off and help recharge the state’s rivers, streams, lakes and ponds, Glisan said.

“We need to see all of the above to bust the drought,” he said.

What’s the rain's impact on farmers, who are trying to plant their crops?

Through Friday, Iowa farmers had planted 39% of their corn acres and 25% of soybean acres. While planting is ahead of the five-year average, rain showers are again forecast through the weekend and early next week.

More: Iowa farmers head into fields, hoping rains will continue, help pull state out of drought

Farmers will need “several days of sunshine for things to dry up,” Mike Naig, Iowa’s agriculture secretary, said in an email Thursday.

“Progress has been slow at our farm in northwest Iowa as it has been for others around the state,” said Naig, whose family farms near Cylinder. “I know farmers are anxious to get back in the field.”

What impact is Des Moines Water Works seeing?

Des Moines Water Works, Iowa’s largest drinking water supplier, anticipates it will need to begin running its nitrate removal system in the days ahead, said CEO Ted Corrigan.

Nitrate levels in the Raccoon and Des Moines rivers, the water utility’s source water, are already over 10 milligrams per liter, the federal standard that drinking water utilities must be below. And it’s pushing close to 20 milligrams per liter, based on tests in northern Iowa, he said.

Nitrogen-based fertilizers used to grow crops can be picked up during rainstorms and carried into drinking water supplies. High levels of nitrates can be deadly to infants, and prolonged exposure to low levels have been tied to some cancers. Nitrates also can contribute to toxic algal blooms that make water supplies difficult to treat or unusable.

The large rainfall helps dilute nitrate levels, but Corrigan expects that once the storms end, levels will rise. Nitrate concentration levels often are high during spring rains after a drought, he said.

"We don't know exactly what to expect, but we anticipate seeing higher nitrates," Corrigan said.

Running the nitrate removal system is costly, reaching about $10,000 a day.

The rains also have been beneficial, Corrigan said, increasing the Raccoon and Des Moines river levels as well as replenishing the shallow aquifers that help provide the metro area’s water supply. Because of the drought, the utility has had to put up flashboards over the past three years to boost Raccoon River levels.

Donnelle Eller covers agriculture, the environment and energy for the Register. Reach her at deller@registermedia.com or 515-284-8457. 

This article originally appeared on Des Moines Register: Rains from tornado-spawning storms have helped lessen drought in Iowa