Water quality group gives Big Sioux River an ‘F’ grade over E. coli contamination

A water conservation non-profit gives the Big Sioux River an ‘F’ grade over E. coli levels beyond what’s considered safe by the state Department of Agriculture and Natural Resources (DANR).

Nitrate levels in the river, fueled in part by agricultural fertilizer runoff, are also rising.

The report card was presented Monday evening at Augustana University in Sioux Falls by Friends of the Big Sioux River (FBSR) in the form of its 2022 water quality summary of the Big Sioux River watershed.

A watershed is an area of land with a common set of waterways and streams that all drain into a single larger body of water, such as a river. To assess the Big Sioux watershed, FBSR took 500 samples at 18 locations along the river, from Dell Rapids to Akron. 

The group reports that over 75% of water samples taken throughout 2022 had E. coli levels considered “unsafe for emersion.”

Water quality degrades in the Big Sioux River as it flows south, according to the nonprofit’s report. The southern monitoring sites at Newton Hills and Akron have higher levels of contaminants.

The primary cause of the unsafe levels is cattle feces, which runs off from farms after rainfall events and makes its way to public waters. A water sample taken just south of Brandon two days after record rain showed E. coli levels almost 200 times higher than the DANR’s allowable limits.

Pollution high in spite of dry conditions

This year’s results are telling, given that the region didn’t receive a lot of rain, said FBSR Treasurer Rachel Koos.

Some Sioux Falls residents want to see the state do something about contaminants. A river with high levels of E. coli running through the state’s largest city is not safe, they say – especially given children play along the river.

FBSR has turned the water sample findings over to DANR. The department is required to issue a water quality report every two years for the federal government.

DANR did not immediately reply to a request for comment regarding the department’s efforts to limit cattle feces from entering the Big Sioux River watershed.

DANR’s biannual reports have shown high levels of E. coli for years. 

Travis Entenman, managing director of FSBR, said the state offers a lot of “carrots” to keep livestock waste out of public water. It may be time for some “sticks,” Entenman said.

“The fines that we give after someone violates a permit could have more teeth to them. Maybe it’s getting cattle out of the water bodies altogether like in many eastern states,” Entenman said. “Or, we could look at what Minnesota has done with mandatory buffer strips.”

A buffer strip is a vegetated area along a stream or river that helps filter out the waste and soil prior to entering the water.  Buffer strip root systems prevent soil erosion along the stream and river banks. 

Nitrates on the radar

FBSR also tests for nitrate levels, which continue to rise but are within safe levels. However, for the second year in a row, nitrates in one water sample exceeded safe levels in the Big Sioux River.

Nitrogen is one of the necessary nutrients for plant growth — it’s often applied to fields in the form of fertilizer. Nitrates are a combination of nitrogen and oxygen.

Nitrates can be carried into watersheds by drain tiles, which are perforated pipes buried under farmland to remove excess water during wet seasons. They stabilize the water table for the crops a farmer has planted, but they also carry anything water soluble with that water – like nitrates.

The number of drain tile projects increased in eastern South Dakota in the 2000s, generally because of increased precipitation and demand for higher yields. Some farmers have taken advantage of the drought to install drain tile where fields had previously been too wet to get the tile installed.

Iowa has experienced the downsides of drain tile, however.

Des Moines had to build nitrate removal facilities in response to drain tiling.

Newborns began developing Infant Methemoglobinemia, or “blue baby syndrome,” where nitrogen levels starve the body of oxygen.

The Big Sioux River is not at that level yet, according to Koos, the FBSR treasurer

“Nitrates are not a really big problem for us right now. But we want to proactively watch it because we know how big of a problem that can be,” Koos said.

‘Heartland River’

The impetus for the event was the release of “Heartland River,” a collection of essays that aim to tell the story of the Big Sioux River. 

The book was not conceived as a means to advance water quality discussions, but some authors featured in the book hope its documentation of the river’s history and cultural significance can serve to inform them.

David O’Hara, director of sustainability at Augustana University, said if people learn the history of the river, they may come to care more about it.

“It wasn’t that long ago that this river was clear as glass,” O’Hara said. “This is going to come down to asking the question, ‘how can we, along the banks of the Big Sioux River, become leaders in water and soil conservation in such a way that we’re making money doing that.”