Damages remain visible in the McCook Lake community on July 3, 2024, after a massive flood hit the area on June 23. (Joshua Haiar/South Dakota Searchlight)

When a record-high surge of water flowed down the Big Sioux River toward the southeast corner of South Dakota last month, local and state authorities activated a flood mitigation plan from 1976.

It saved North Sioux City and Dakota Dunes from disaster. But their neighbors in McCook Lake suffered a graphic reminder of how different their community is today than it was 48 years ago.

“Back when there were a few little cabins on the lake that you could replace for $20 apiece, and now there are little McMansions,” said Jay Gilbertson, geologist and manager of the East Dakota Water Development District, based in Brookings. 

‘We have nothing’: Flood victims say government failures continue after botched flood warning

He said it’s time for an update.

“Most definitely. The idea that a plan drawn up back then would still be applied today is kind of silly.”

Utilizing the existing plan, local and state authorities plugged the area under an Interstate 29 overpass with a sandbag-and-clay levee, to tie in with permanent levees that protect North Sioux City. The system diverted water toward McCook Lake, as intended.

But there was more water than anybody had ever seen before. Instead of causing a manageable rise in the lake, floodwaters slammed into dozens of homes, destroying around 30 of them and carving giant gouges in the land on the lake’s north shore. Fortunately, nobody was killed.

Union County Emergency Management Director Jason Westcott said officials thought the plan would work as it had in the past. Now he says something needs to change.

“We’re having a bad flood every four or five years,” he said. “Our rivers are changing and us humans are doing something to them.”

Some researchers and scientists say the changes are due to a greater frequency of severe rainfall and shifts in land use. And they say mitigation plans have not kept up.

“There’s no question about it,” said Carter Johnson, distinguished professor emeritus of ecology at South Dakota State University. “Mitigation plans, building standards and regulations are based on the 20th century data, which made sense, but we’re changing.”

Mark Sweeney, an environmental science professor at the University of South Dakota, shares those concerns. 

“Flood mitigation plans should never be considered static,” Sweeney said. “River channels are in a constant state of change, meaning flood hazards are likely to change, especially over decades.”

The recent flooding began when three days of heavy rainfall inundated southeast South Dakota, southwest Minnesota and northwest Iowa. The McCook Lake community did not anticipate the volume of water that overwhelmed some of their homes on June 23, according to Dirk Lohry, president of the McCook Lake Association.

But in hindsight, the disaster looks like another step in a progression of more frequent, more severe floods affecting the area during the past 15 years.  

“I’m 1,000 years old,” Lohry said. “I have now lived through two once-every-500-year floods.”

A changing environment

Warning signs have been accumulating in recent years about changing river flows in eastern South Dakota.

A U.S. Geological Survey report found a 298% increase in streamflow for the James River near Scotland, for example. The report says increases are linked to higher precipitation, urban development, tile drains used under farm fields, and grassland-to-cropland conversion.

The report found “a hydrologically unique trend in the eastern Dakotas that is not being observed anywhere else in the conterminous United States.” 

“Specifically, streams in the eastern Dakotas have experienced the greatest increases in streamflow during the last 60 years in comparison to any other USGS gaged stream in the United States.”

When North Sioux City developed its flood mitigation plan almost five decades ago, the highest recorded flow rate of the Big Sioux River in the city was 77,500 cubic feet per second, according to a North Sioux City official who spoke during a July 1 city council meeting. The flow during the recent flooding overwhelmed stream gauges, reaching what some city officials estimated to be 170,000 cubic feet per second.

Severe floods across the Midwest are becoming more common, mostly due to a greater frequency of severe rainfall, said Jonathan Remo, a geologist at Southern Illinois University. He said the “once-every-500-year” title given to some floods is a probability based on historical data.

“But we’re now seeing an unprecedented frequency of major precipitation events,” Remo said. “Something has fundamentally changed, and it’s related, in part, to climate change.”

Around the globe, large amounts of heat-trapping greenhouse gases are being emitted into the atmosphere. Warmer air holds more moisture, which, when it condenses, results in more intense precipitation. 

The state climatologist at South Dakota State University, Laura Edwards, has been saying for years that South Dakota’s climate is becoming wetter during wet cycles and drier during dry cycles, translating to more severe droughts and floods.

Carter Johnson, also of SDSU, has studied climate change for decades and said, “We’re seeing changes at rates that have never been observed before.” 

He said South Dakota can fund better preparation and mitigation for natural disasters, or spend more on recovery.

“Taxpayers are paying for it either way,” he said. “Insurance rates will continue to go up, natural disasters will continue to happen, and emergency response and cleanup is not cheap.”

Land-use changes

USD’s Sweeney said climate change is the biggest concern for the future, but added that changes to the landscape, like urban sprawl, are also contributing to worsening floods. He said water that would normally soak into the ground like a sponge, slowing its flow rate, now hits asphalt and runs right off. 

“We have known for a long time that runoff from asphalt is faster than from grassland,” Sweeney said.

Drain tile — perforated pipe installed under cropland to drain excess moisture — is another factor. When drain tile systems are installed, water that would otherwise accumulate in a field before absorbing into the ground or evaporating is instead channeled into ditches, creeks and rivers.

“Personally, I think tile drains are a slow-motion experiment we are playing,” Sweeney said.

A 2014 study in Ohio found that tile drainage significantly contributed to the amount of water discharged in the watershed. In Iowa, 2016 research indicated that tile drainage significantly alters streamflow, contributing 30% more water to the observed streams during precipitation events.

Converting grasslands to cropland can also make flooding worse. 

Meghann Jarchow, a USD professor of sustainability and grassland specialist, referenced a study showing grassland holds more water than cropland, with or without cropland drainage systems. Prairies have a thick layer of plant material that soaks up rain, which leads to less water draining away.

“We’ve changed so many things in our environment,” she said. “Policies need to keep up.”

Between 2008 and 2016, nearly 5 million acres of grassland were converted to cropland across 12 Midwestern states – including South Dakota – primarily for corn and soybean production, according to a 2021 study. That’s the equivalent of about five Rhode Islands. 

Solutions

For the residents of McCook Lake, one priority is clear: They want assurance that their homes will not be “sacrificed” again.

“They’ve got to change that plan,” Dirk Lohry said.

McCook Lake residents called on North Sioux City officials to change the current mitigation plan during a July 1 meeting, suggesting a large ditch be built to direct water to nearby Mud Lake — which does not have a community surrounding it — rather than McCook Lake.

Jay Gilbertson thinks it’s time those “once-every-however-many years” estimates get updated, partly because of how those odds drive design standards for infrastructure like waste management systems and dams. 

“You might have to make a system able to handle a once every 50-year event based on historical records,” Gilbertson said. “But 50 might not be 50, it might be 30.”

He said those adjustments could help ensure dams and levees are being built for the environment of the 21st century and beyond, not the 20th. 

Federal agencies and state and local governments are all responsible for updating design standards to reflect current climate data.

Zoning laws could also be updated to illustrate flood zones more accurately, Gilbertson said, restricting development in high-risk areas, and ensuring adequate park and wetland space to help absorb floodwaters. 

In 2020, State Climatologist Laura Edwards wrote about increased flood risks in South Dakota, highlighting how many properties are at greater risk than currently indicated by Federal Emergency Management Agency (FEMA) flood plain maps. Multiple McCook Lake residents told South Dakota Searchlight they do not have flood insurance, because of the expense and because they’re not in an area designated by FEMA as requiring it.

Sweeney said the accuracy of flood plain maps is critical, as are local government decisions about what development, if any, is allowed.

“We will never be able to eliminate flood hazards as long as the government allows people to build in flood plains,” Sweeney said.

SIOUX FALLS, S.D. (KELO) — A Microsoft outage is affecting South Dakota.

Dan Letellier with the Sioux Falls Regional Airport said Delta and United Flights are delayed.
He recommends travelers check their airline website for updated flight information.

The Rapid City Regional Airport said on its X account, that because of the “global technology issues impacting multiple airlines, we anticipate significant delays throughout the day. We ask customers to verify your flight status with your airline prior to heading to the airport.”

The city of Sioux Falls posted on its Facebook page that its website is affected by the Crowdstrike outage. The city said it is working with vendors to restore access as soon as possible.

The city said customer self service is working

The airport’s website is apparently having issues as flight statuses have not been updated this morning, Letellier speculated the issues are related to the outage.

The outage is a Microsoft outage linked to Crowdstrike, multiple media are reporting.

The outage has caused issues around the world. Long lines formed at airports in the U.S., Europe and Asia as airlines lost access to check-in and booking services. Cybersecurity firm CrowdStrike says that the issue believed to be behind the outage was not a security incident or cyberattack.

The first case of measles in South Dakota in nine years was reported Thursday by the state Department of Health.

Measles is a highly contagious viral disease that can cause health complications, especially in children younger than 5 years old.

The case was found in a Pennington County adult who traveled internationally and tested positive at Monument Health in Rapid City this month. The patient could have exposed people at the Black Hills Urgent Care from 10 a.m. to 2:30 p.m. on July 9 and the Monument Health Rapid City Emergency Department waiting room from 5 p.m. to 12 a.m. on July 12, the Department of Health said.

“Measles is a highly contagious viral disease and spreads through the air when an infected individual coughs or sneezes,” said Dr. Joshua Clayton, state epidemiologist, in a news release Thursday. “Individuals who have not been fully immunized with two doses of measles vaccine have an increased risk of infection if they have contact with an infected person.”

The measles vaccine is typically given to children between 12 and 15 months old, with the second dose given at 4 to 6 years old. Two measles shots usually produce lifelong immunity, according to the news release.

The last time a measles case was reported in South Dakota was in January 2015, when there was an outbreak of 13 cases in the Mitchell area and one case in an unvaccinated Sioux Falls 10-year-old.

Aside from an unvaccinated child younger than 5 years old contracting measles in Mitchell in December 2014, South Dakota hadn’t had a measles case since 1997.

Measles appears in two stages. First, the patient may have a runny nose, cough, slight fever and reddened eyes sensitive to light. Second, on the third to seventh day, the patient has a temperature of 103-105 degrees Fahrenheit and a red, blotchy rash beginning on their face and spreading across their body. The rash lasts up to a week.

Measles, mumps and rubella (MMR) vaccination rates have been on the decline in the United States for over a decade after the disease was declared eliminated in 2000. More than 160 cases have been reported nationwide so far in 2024, with 53% of cases hospitalized. Over 60% of cases in children younger than 5 years old have been hospitalized so far this year.

South Dakota’s MMR vaccination rate among kindergarteners decreased from 96.8% during the 2009-2010 school year to 92.5% during the 2022-2023 school year, according to the Centers for Disease Control. That is below the Office of Disease Prevention and Health Promotion’s goal of 95%, which establishes herd immunity.

Children entering school or an early childhood program in South Dakota must have received, or be in the process of receiving, two doses of the MMR vaccine and some other vaccines. Exemptions are available if a licensed physician says it would endanger the child’s life or health, or if the child’s religious doctrine opposes immunization.