State sues Sioux City for Missouri River pollution from wastewater plant

For years Sioux City has failed to properly treat its wastewater to ensure excessive amounts of bacteria or treatment chemicals weren’t expelled into the Missouri River, according to a state lawsuit that was filed against the city Friday.

“The city potentially endangered human lives and wildlife by violating water-quality rules and perpetrating a fraud to conceal its employees’ actions,” Iowa Attorney General Tom Miller said.

Miller’s office is litigating the issue on behalf of the Iowa Department of Natural Resources, which oversees treatment plants in the state. Guy Cook, an attorney for Sioux City, said the fault lies with two former city employees.

“Contrary to the lawsuit claims, no people or wildlife were endangered by the rogue actions,” Cook said. “Likewise, there was no ‘scheme’ or ‘fraud’ by the city, only rogue actions of the two men who were fired.”

Problems at Sioux City’s wastewater treatment plant — which disinfects millions of gallons of wastewater each day and discharges it into the Missouri River — have persisted for about a decade after a new disinfectant process began in 2011, the lawsuit alleges. The next year, an engineering firm found that large amounts of wastewater from industrial sites were interfering with chlorine the plant used to eliminate biological contaminants such as E. coli bacteria.

The firm concluded the treatment plant could not adequately disinfect the wastewater and recommended additional sampling and other disinfection methods in a draft of a master plan it produced under a $1 million contract with the city, the lawsuit says, but the city told the firm not to finalize the plan and later hired a different engineering firm.

For the following two years, workers at the plant juked tests of the wastewater to conceal the problem from the DNR, which led to the federal prosecution of the plant’s former superintendent and a shift supervisor for Clean Water Act violations.

Superintendent Jay Niday was sentenced to three months in federal prison last year for charges of conspiracy and knowingly falsifying the tests, to which he pleaded guilty. Supervisor Patrick Schwarte pleaded guilty to the same charges in 2019 and got probation.

“Jay Niday deliberately worked with others to cheat on environmental tests, knowing he was polluting the Missouri River,” U.S. Attorney Sean Berry said in April. “His actions not only put recreational users of the river at risk, but also endangered the river’s aquatic life. Niday’s blatant disregard for the law, the safety of the community, and his reprehensible treatment of a vital waterway was outrageous.”

The issue came to light in 2015 when someone at the plant sent a letter to the DNR that alleged the plant was only treating wastewater sufficiently for E. coli on days the staff sampled it for state-mandated testing.

On typical days, the plant was using liquid chlorine at a rate of about 2.5 gallons per hour to kill bacteria, but on testing days it used between 70 and 120 gallons per hour to pass the test, Berry said. Staff then reduced the flow of chlorine before testing the treated wastewater for the chemical, which is also regulated by the state and shouldn’t exceed certain levels.

Cook said the city promptly fired Niday and Schwarte when it became aware of the testing falsifications.

“The city has since taken considerable steps and dedicated substantial resources to upgrade and improve the wastewater treatment plant,” Cook said. “Those improvements are ongoing.”

The plant has continued to struggle to limit the amount of chlorine and ammonia that reaches the river, according to the lawsuit. In August, it notified the DNR it had expended all of its supply of sodium bisulfate, which is used to remove chlorine after the chlorine has killed the bacteria. However, it was able to acquire more of the chemical the next day.

The lawsuit seeks fines of up to $5,000 per day for the violations and a court order for the city to comply with DNR regulations.