South Dakota
South Dakota's mosquito war
SOUTH DAKOTA (SDNW)– A South Dakota county with the second-highest national rate of lethal West Nile virus in humans shares a border with a county that has never reported a single case.
Between 1999 and 2023, Dewey County recorded 13.74 neuroinvasive cases per 100,000 people, just behind King County in Texas, according to the U.S. Centers for Disease Control and Prevention. Neuroinvasive refers to those more serious cases that can affect the brain and can be deadly.
Ziebach County, which borders the western boundary of Dewey County in north-central South Dakota, shows zero neuroinvasive West Nile virus cases, according to the CDC. The Cheyenne River Indian Reservation covers most of both counties.
“That’s wild,” Randolph Runs After, environmental health specialist at Cheyenne River Sioux Tribe, said after learning about the Dewey County ranking. “We actually haven’t had that many cases in the last few years.”
The data aren’t wrong but needs explaining.
“The medical facility for both counties is in Eagle Butte, Dewey County, and they are the ones who report to the health department,” said Michael Claymore, director of the Cheyenne River Sioux Tribe Prairie Management Program.
Population numbers also impact incidence rates, Tia Kafka, marketing and outreach director at the South Dakota Department of Health, said in an email. The fewer residents live in a county, the more impact a single West Nile virus cases will have, she said.
“Historically, Brown County has been the hotspot for West Nile virus activity in South Dakota, with the most cumulative West Nile virus cases reported,” Kafka said.
Brown County, whose county seat is Aberdeen, recorded more than 340 West Nile virus cases between 1999 and 2023, which ranks it 24th among other counties in the United States, the CDC said. Within South Dakota, Brown County is followed by Pennington County, with more than 220 West Nile virus cases during that time, and Minnehaha County, with almost 200 incidents.
The U.S. Department of Health and Human Services defines a high incidence rate as one that is greater than 1.1 per 100,000 people. Analysis of the CDC’s historic data within this framework showed that 61 out of 66 South Dakota counties – which amounts to 92% – have a high incidence of West Nile virus cases in humans.
When bitten by a West Nile virus-carrying mosquito, most people will not show any symptoms, said Erin Staples, M.D., medical epidemiologist with CDC’s Division of Vector-Borne Diseases. Some will develop West Nile fever, but even fewer will get a neuroinvasive West Nile virus disease, which affects the brain or the space around it. Non-neuroinvasive cases are generally less serious.
Virus reached SD in 2002, has been declining
Runs After remembers the first years of West Nile virus in South Dakota when “you could find dead birds here and there.”
The first reported case was in 2002 in a crow in Aberdeen, according to a Rapid City Journal story from July 2002.
West Nile virus first appeared in the United States in New York City in 1999 and reached the West Coast by 2004, Staples said. She added that a lot of people got infected at the time because “there was no immunity in anybody.”
Since 2002, the South Dakota Department of Health has recorded more than 2,800 human cases, 53 of which were fatal.
In 2003, Virgil Christensen, an 89-year-old man from Wakonda in Clay County, became the first South Dakotan to die from West Nile, according to the Vermillion Plain Talk.
Both South Dakota and the United States observed a peak in the number of West Nile cases that year. The state Department of Health recorded 1,039 occurrences.
This year, the South Dakota Department of Health has already recorded the first West Nile virus case of 2024.
The department’s West Nile Virus Surveillance tool shows that this non-neuroinvasive case of West Nile virus disease was found in a resident of Beadle County who is at least 64 years old.
The CDC’s surveillance tool shows that neighboring North Dakota and Nebraska have already recorded one and four cases, respectively.
Weather and human activity increase mosquito numbers
As of July 17, the South Dakota Department of Health predicted 48 West Nile virus cases for 2024 in the state.
Kafka said the state health department uses a model, updated weekly, that considers factors like historical human West Nile virus case data, environmental data, and current year mosquito pool testing data.
Historically, late July and August tend to accumulate the highest number of West Nile virus cases across the United States.
South Dakota experiences the same trend because of “several interrelated factors,” Kafka said.
Mosquitoes that can transmit West Nile virus reach their highest population numbers during the warm summer. In addition, heavy rains create puddles and stagnant bodies of water, which are favorable conditions for mosquitoes.
“Warmer temperatures not only support mosquito breeding but also accelerate the development of the virus within mosquitoes, enhancing the risk of transmission to humans,” Kafka said.
People also like to spend more time outdoors during the summer, camping, hiking, and participating in evening gatherings, which increases their chances of encounters with mosquitoes, she said.
Mosquitoes are ‘the main culprit’
Staples, of the CDC, said West Nile virus is usually transmitted through a mosquito bite.
When bitten by a West Nile virus-carrying mosquito, some people will not exhibit any symptoms at all, she said. One in 5 will develop a febrile illness, which may involve getting a fever, a rash, a headache, muscle pain or joint pain. This is also referred to as West Nile fever.
Some people will go on to develop a West Nile neuroinvasive disease. This can lead to encephalitis, which is inflammation of the brain, or meningitis, which is inflammation of the tissues around the brain and spinal cord, Staples said.
“Mosquitoes are often referred to as the deadliest animal in the world, as they cause more death and disease than any other animal on the planet,” Staples said.
Birds also contribute to the spread of West Nile virus. Once infected, they can develop enough virus to pass it on to a non-infected mosquito, which is why they are sometimes called “amplifying hosts,” she said.
Humans do not have the same capabilities, although they can spread the virus to one another through blood transfusion, Staples said.
Several vaccines have gone through the early stages of clinical development but are currently stuck at the part called efficacy trial, she said.
“You need to be able to say, ‘Where is there West Nile? I’m gonna start vaccinating people and look to make sure that the vaccine is very effective and can prevent infection,’ Staples said. “Unfortunately, we haven’t been able to necessarily predict where West Nile is going to occur. That’s really the sporadic and unpredictable nature of West Nile virus.”
CDC and state fund mosquito control
The South Dakota Department of Health received almost $1.5 million in 2023 for the department’s West Nile virus media campaign and laboratory testing of mosquito pools through the CDC’s Epidemiology and Laboratory Capacity Program.
This year, the state Department of Health allocated $500,000 in grant funds to distribute among cities, counties and tribes for mosquito control in amounts ranging from $500 to $20,000. Kafka said that 166 applicants received money based on the population and history of human cases.
The Cheyenne River Sioux Tribe Prairie Management Program received $9,325 as part of the grant.
Claymore said the Prairie Management Program tries to eradicate mosquitoes in several different ways. He said the team monitors traps and tests captured mosquitoes to see if any of them carry viruses.
The program also conducts larva sightings, which involve putting chemicals in standing water to kill mosquitoes before they get a chance to develop into adults.
Workers also spray the ground, fog the trees and disperse microscopic droplets of a chemical compound mixed with oil through aerial fogging.
Claymore said the program uses all of the Department of Health grant money to buy just enough chemicals to last a season.
“I tell people to just watch the news and see where the mosquitoes are at, and they are moving towards us,” Claymore said. “Now it’s really important to be more vigilant with your personal protection.”
Mosquitoes in Sioux Falls ‘as bad as ever’
The city of Sioux Falls, Aberdeen and Pennington County, received $20,000 each.
Dominic Miller, environmental health manager for the Sioux Falls Department of Health, said in an email the city’s mosquito control program was created the same year the city recorded its first West Nile virus case, 2003. Now that over 20 years have passed, the number of mosquitoes in 2024 is “as bad as (the city has) ever seen it,” he said.
The city of Sioux Falls is divided into 18 spraying zones, and each zone has at least one mosquito trap. Every morning during weekdays, the mosquito control team checks all traps to count and test captured mosquitoes.
This summer, one of the traps collected 6,300 mosquitoes overnight, Miller said.
The mosquito control team uses the number of trapped mosquitoes to determine what zones to spray and aims to eradicate all kinds of mosquitoes, not just those that may carry West Nile virus, he said.
Ways to prevent infection
Kafka said homeowners can minimize the risk of being bitten by installing or repairing window and door screens to keep mosquitoes outside of homes.
The state Department of Health also encourages people to reduce the risk of being bitten by mosquitoes and contracting West Nile virus by joining “the S.W.A.T. team:”
- Spray: When outdoors, apply mosquito repellents that contain compounds like DEET, picaridin, 2-undecanone, param-menthane-diol, IR3535 or oil of lemon eucalyptus.
- Water: Remove standing water from old tires, buckets and other containers that can give mosquitoes a place to breed; regularly change the water in bird baths and pet dishes, and stay away from areas near standing water.
- Arms: Wear pants and long-sleeved shirts to cover exposed skin.
- Time: Limit time outdoors at dawn and from dusk until midnight when mosquitoes are most active
Susan Hoover, M.D., an infectious disease physician at Sanford Health, said that since there is no treatment for West Nile virus, it’s paramount to take those precautions.
If a person is bitten and exhibits such symptoms as fever, vomiting, diarrhea, headache or body aches and suspects they may have West Nile virus infection, they should contact their health care provider, she said.
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The existing water treatment plant for the Minnehaha Community Water Corp. on June 9, 2026, south of Dell Rapids, S.D. (Photo: Bart Pfankuch / South Dakota News Watch)
DELL RAPIDS, S.D. – Scott Buss can only imagine what this town north of Sioux Falls might have looked like – and how many jobs and taxes would have been generated – if there wasn’t a local shortage of available water.
Buss, executive director of the Minnehaha Community Water Corp., sat in the conference room of the rural water system based in Dell Rapids recently and ticked off the industrial and agricultural projects turned away due to a lack of water.
After hitting its limit on how much water it can provide a few years ago, the rural system has had to turn away proposed projects valued at hundreds of millions of dollars that offered an untold number of new jobs, he said.
The rejected projects include the Agropur Cheese plant that eventually opened in Lake Norden. A few proposed hog farms and dairy expansions in northern Minnehaha County were also stalled, Buss said.
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Other proposals, most of which never came to fruition in South Dakota, included the $1.5 billion Gevo corn-based jet fuel plant, the $5oo million Wholestone Farms hog processing plant and a data center that at some point all eyed the Dell Rapids area for development.
“All the water rights are spoken for between Dell Rapids and Sioux Falls, so there was no more water to be had in Minnehaha County,” Buss told News Watch in an interview in June. “With all the (residential) development that was coming in, we realized that our well capacity and our treatment capacity was limiting our ability to take on new high water-use customers.”
Buss and the nonprofit corporation’s board of directors aren’t waiting around to potentially miss out on more opportunities.
In a unique arrangement, the corporation is partnering with the neighboring Big Sioux Community Water System to the north on a $170 million expansion project called Shared Resources. The expansion, started three years ago, will use new wells into the Big Sioux Aquifer to generate 8 million gallons of water more per day starting this fall.
“It’s going to be a huge and great benefit for Big Sioux and Minnehaha water,” said Jodi Johanson, director of the Big Sioux system based in Egan. “This project is going to make sure that down the road we have enough water for the future.”
2 systems get stronger together
The Minnehaha water corporation is still able to bring on new residential and retail customers who consume part of the 9.2 million gallons of treated water it can provide on a daily basis.
The system was formed by a group of farmers and landowners in the 1970s but sought a reliable way of providing more and cleaner water to residents of Minnehaha County outside of Sioux Falls who relied exclusively on individual wells. The system started with about 1,200 customers but has grown to more than 5,500 now in seven cities, mostly north of the Sioux Falls metro area.
Given the limits on water from the aquifer, and balancing the water needs of consistent housing and retail growth in northern Minnehaha County, the water system had to say no to developments that request 1 million or more gallons of water per day, Buss said. A million gallons per day is equivalent to the water consumption of about 4,300 homes, he said.
Billions needed to keep South Dakota taps flowing
South Dakota water systems will increasingly turn to the Missouri River to provide water for future population, agricultural and industrial growth. But plans will require billions of dollars and decades of construction to keep taps flowing freely.
As with other rural water systems in South Dakota, the aquifers the systems rely on for their water are either running low or are legally tapped out, or both.
In the case of Minnehaha water corporation, the Big Sioux River Aquifer has gotten drier, but state law is also preventing it from taking more water from the aquifer.
In 1996, the state Water Management Board allocated water rights, or withdrawal limits, to systems that take groundwater from the aquifer, Buss said.
Those limits have now been reached, meaning that Minnehaha water cannot take any more than the 7 million gallons per day it is drawing now.
The system also receives about 2 million gallons per day from the Lewis & Clark Regional Water System, making its daily maximum capacity of about 9.2 million gallons per day, which it sometimes reaches, especially during spring planting season or hot summer months.
Directly to the north, the Big Sioux Community Water System produces up to 2 million gallons per day for about 2,400 customers in Moody and Lake counties as well as some in Brookings County and in western Minnesota, Johanson said.
The system still has room within its water rights to draw more water, making it an attractive partner for Minnehaha water.
Though Big Sioux Community Water System has not turned away any large projects, it needs more water to serve a boom in residential growth in the region, Johanson said.
In the area around Lake Madison, near Madison, developers are considering projects that could someday bring 500 new homes and a new nine-hole golf course, she said.
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The system also serves a number of dairies that use significant water and provides water to the Dakota Ethanol plant in Wentworth, which is undergoing an expansion. Farmers in the region are also using greater quantities of water to deliver chemicals onto their land, Johanson said.
“This is our first expansion,” she said. “We’re looking forward and we’re trying to find the solution before we face a problem.”
Federal government and customers pay the way
The biggest Shared Resources ticket item is a new $80 million water treatment plant that is nearly completed on 240th Street a few miles north of Dell Rapids.
A 20-inch pipeline from the plant to the east will end at a 1.5 million gallon water tower, and a 24-inch pipeline to the west will terminate at a ground-level storage tank with a 4 million gallon capacity.
Six new wells will draw the water, and the storage tanks will provide both pressure and the ability to adapt to changing demands without service interruption, Buss said.
As with most modern water projects, the costs will be shared by government and end users. The systems are funding the project with $49 million in grants from the Biden-era American Rescue Plan Act and $121 million in low-interest loans from South Dakota’s Drinking Water State Revolving Fund.
The two systems are sharing the cost of the project loans commensurate with how much water they will receive, meaning Minnehaha will pay 65% of the costs for its 5 million gallons per day while Big Sioux will kick in 35% for its 3 million gallons more per day.
Minnehaha water is assuming $87 million in new debt and Big Sioux will take on $42 million in new debt, Buss said.
The average residential consumer in both systems that uses about 7,000 gallons per month will see their bill rise to $135 a month, roughly double the cost in 2020.
“It’s a big project, and it’s a good example of how two systems can work together to have some economies of scale,” Buss said.
Ratepayers will see a significant increase in their monthly water bills. The average residential consumer in both systems that uses about 7,000 gallons per month will see their bill rise to $135 a month, roughly double the cost in 2020, Buss said.
A big project, but even more water needed
But both systems view the Shared Resources project as a temporary fix and both are looking toward proposed projects that will tap the Missouri River for more water in the future.
Buss said his system has applied for 10 million gallons more water per day from Lewis & Clark, which has two expansion efforts planned.
Minnehaha water has simultaneously applied to receive 10 million gallons per day from the proposed Dakota Mainstem Regional Water System, a potentially $10 billion project to carry Missouri River water to more than 50 communities and organizations across eastern South Dakota and parts of Minnesota and Iowa.
The dual application effort is to make sure Minnehaha water can rely on taking in more water from at least one of the two systems as they come online, Buss said.
Johanson said Big Sioux has also signed on to accept water from Dakota Mainstem, even if it takes 20 to 40 years for the water to begin flowing.
To ensure that steady supply of high-quality drinking water, four major projects are in progress to take more water from the Missouri River – including WEB Water in the northeast, Lewis & Clark and the proposed Dakota Mainstem in the southeast as well as the proposed Western Dakota Regional Water System in western South Dakota and the Black Hills.
The projects are part of a wide-scale increase in water service capacity now underway in South Dakota, where water managers of several systems are implementing plans to serve the state for the next 40 to 50 years.
Regional rural water systems such as Minnehaha and Big Sioux are critical components of those projects because they provide water to communities and individual customers at the end of the delivery system.
Alicia Deschepper, zoning administrator for Moody County, said the water system expansions should allow for more growth to occur in Moody and Minnehaha counties, which are seeing new single-family housing developed at a rapid rate.
“I think it will be a great thing for our county and hopefully enable us to bring in more bigger businesses as well as more homes,” Deschepper said.
South Dakota News Watch is an independent nonprofit. Read, donate and subscribe for free at sdnewswatch.org. Contact content director Bart Pfankuch: 605-937-9398/bart.pfankuch@sdnewswatch.org.
SIOUX FALLS, S.D. (Dakota News Now) – The South Dakota Department of Public Safety said a nine-year-old girl from Waterloo, Iowa, is dead following a fatal Hughes County crash on Saturday.
This crash happened on Saturday, July 4, near the Spring Creek Recreation Area about 15 miles northwest of Pierre.
Preliminary crash information suggests a utility vehicle driven by a 37-year-old Iowa man was driving south on Spring Creek Drive. He attempted to turn around and rolled the vehicle.
A 16-year-old boy was also in the vehicle and was hurt, while the driver was not hurt.
The South Dakota Highway Patrol is investigating the crash.
Copyright 2026 Dakota News Now. All rights reserved.
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