As much as 900 gallons of agricultural chemicals – including the primary component of the weed-killer Roundup – flowed into the Big Sioux River after a truck rolled over and spilled its load near Estelline in eastern South Dakota in late June, South Dakota News Watch has confirmed.

A semi truck carrying a flatbed loaded with agricultural herbicides rolled off a road in Hamlin County near Estelline on June 26, sending up to 900 gallons of chemicals into the adjacent Big Sioux River. The driver was not injured in the wreck. Photo: Courtesy South Dakota Department of Highway Safety

The liquid herbicides that spilled on June 26 included glyphosate, used in Roundup, as well as dicamba and acetochlor, also chemicals used to control weeds on farms, according to Katherine Jenkins, a community-involvement coordinator for the U.S. Environmental Protection Agency. Acetochlor is the only one of the three chemicals defined by the federal government as a “probable carcinogen,” though glyphosate has recently been linked to one form of cancer.

Jenkins said the agency had run tests both upriver and downriver from the accident site and believed that high water flows in the Big Sioux River allowed the chemicals to fully dissipate in the water. No humans, animals or fish were known to have been hurt by the chemical release, she said.

“The chemicals have dispersed and are no longer a threat to the area,” Jenkins said. “The analytical results show that the traces of those chemicals are no longer in the river.”

Jenkins said a diesel tank on the truck also ruptured and spilled fuel and oil into a ditch next to the Big Sioux River. A dirt berm was created to block those materials from entering the river, and a vacuum machine was used to remove them from the site, Jenkins said. The dirt berm will eventually be removed and trucked to an approved toxic-waste dump, she said.

While no public drinking water systems pull water directly from the Big Sioux River near the spill site, several regional water systems, including the city of Sioux Falls, get drinking water from the underground aquifer supplied by Big Sioux River water.

The day after the accident, the city of Sioux Falls shut down its drinking-water wells located closest to the river and began testing river water and its treated water from the aquifer to check for any residual chemicals related to the spill, said Tim Stefanich, environmental engineer and lab supervisor for the city. No traces of chemicals from the spill were found, he said.

“Everything came back clean,” Stefanich said. “We haven’t seen anything above the background of what’s normal in the river; that is, what’s normal for a watershed that has agriculture and typical runoff.”

The day after the June 26 crash, a bulldozer built an earthen berm around the area in an unsuccessful attempt to prevent spilled chemicals from entering the Big Sioux River, visible at upper left. Photo: Courtesy U.S. EPA

Glyphosate has been in the news recently after a federal jury ruled in May that a California couple should receive about $2 billion in damages after claiming they contracted non-Hodgkin’s lymphoma, a type of cancer, after using the chemical on their farm for 35 years.

Since the ruling, attempts have arisen to file class-action lawsuits on behalf of people who claim they got cancer from Roundup. The U.S. Centers for Disease Control & Prevention published a research review in April noting that although “most studies found no association between exposure to glyphosate-based products and risk of cancer,” testing showed there is “a possible association between exposure to glyphosate and risk of non-Hodgkin’s lymphoma.” The CDC also noted that exposure to glyphosate can affect the development of infants and can damage the urinary tracts of adults.

Dicamba, also known commercially as Banvel and Oracle, is an herbicide that has been criticized by some farmers in South Dakota and elsewhere who say the chemical has drifted from neighboring properties onto their land, where it has led to crop losses. The South Dakota Department of Agriculture has a page on its website devoted to helping farmers document and report any damage caused by dicamba. Dicamba exposure is known to cause reduced weight during maternity and also fetal toxicity, according to the CDC.

Acetochlor is also an herbicide that can have significant negative impacts on human health, including damage to the nervous, reproductive, hepatic, urinary and hematological systems within humans. Exposure to the chemical can also hinder the proper development of a fetus, the CDC said. The chemical is also listed as “moderately toxic” to fish and honeybees, the CDC said.

Officials with the U.S. Environmental Protection Agency sample water in the containment pool that was created in an attempt to keep spilled chemicals out of the Big Sioux River. Absorbent flotation materials can be seen in the water. Photo: Courtesy U.S. EPA

According to the South Dakota Highway Patrol, the accident occurred at 4:55 p.m. on June 26 about two miles south of Estelline. The patrol said a 2005 Kenworth T800 semi pulling a flatbed trailer loaded with chemicals was southbound on 465th Avenue near 196th Street and tipped over into the ditch, pulling the truck’s cab onto its side. The driver was not injured, the patrol said. Charges are pending against the driver in the crash that happened on a left-hand curve in the road, the patrol said.

Once the spill occurred, police and emergency management officials from Watertown and Hamlin County were dispatched and began immediate assessments and attempts to prevent chemicals from flowing into the river.

The day of the spill, the EPA was notified through a national spill-alert system and by the South Dakota Department of Environment and Natural Resources, according to an EPA timeline. Two EPA employees flew in and spent about three days in South Dakota to help coordinate the response, which included construction of an earthen berm, deployment of absorbent materials and use of a containment boom.

Jenkins said the river was flowing too fast to prevent the chemicals from entering the river. Some of the spilled materials may have also entered the river on July 2 after flooding in the Big Sioux River washed out the containment berm, which then had to be rebuilt, the EPA said.

“With the chemicals, they tried to contain it in that area but with the flood and rising flood waters, it went downstream,” she said.

Dana Loseke, chair of the nonprofit group Friends of the Big Sioux River, said it was fortunate the accident happened at a time the river is flowing much higher and faster than normal.

“I’d say we dodged a major bullet, and it could have been a lot worse,” Loseke said. “You have to look at it simply as a bad break for the river, not like it’s a chronic thing that could happen every few months.”