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Press Release

Former Sioux City Wastewater Treatment Plant Shift Supervisor Sentenced for Violating the Clean Water Act

For Immediate Release
U.S. Attorney's Office, Northern District of Iowa
Rigged Environmental Testing for Years

A Sioux City man who conspired to rig environmental testing at a large Iowa regional wastewater treatment plant was sentenced today.

Patrick James Schwarte, age 71, from Sioux City, Iowa, received the sentence after a January 23, 2019, guilty plea to one count of conspiracy and one count of knowingly falsifying, tampering with, and rendering inaccurate a monitoring device or method required to be maintained under the Clean Water Act.

The evidence at the guilty plea and sentencing hearings showed that Schwarte was employed at the Sioux City Wastewater Treatment Plant (WWTP) for over 30 years, most recently as shift supervisor.  Schwarte maintained a wastewater treatment certification from the State of Iowa’s Department of Natural Resources (IDNR) and possessed extensive training and experience in municipal wastewater treatment.

The WWTP is a large regional sewage treatment plant for wastewater from industrial, commercial, and residential sources throughout Siouxland, including Sergeant Bluff, Iowa, South Sioux City, Nebraska, North Sioux City, South Dakota, and Dakota Dunes, South Dakota.  The WWTP’s more than 20 industrial users produce a large volume of high-strength wastewater.  Under a Clean Water Act (CWA) permit, the WWTP was required to treat wastewater before discharging it into the Missouri River, which has heavy local recreational use.  Between March 15 and November 15 each year, when public use of the Missouri River was at its highest levels, the WWTP was also required to disinfect its wastewater to remove potentially dangerous human pathogens, including fecal coliform bacteria or E. coli.

The WWTP treated its wastewater with liquid chlorine, which kills bacteria but is potentially toxic to aquatic life.  The WWTP’s permit required WWTP to periodically test its wastewater not only for the presence of fecal coliform bacteria or E. coli, but also total residual chlorine (TRC) levels, to ensure that the Missouri River was not polluted.           

From July 2012 through June 2015, Schwarte and his direct supervisor, the WWTP Superintendent, tampered with the monitoring methods at the WWTP in order to ensure the WWTP would pass all of its tests.  Specifically, early in the morning on testing days for bacteria, Schwarte and the Superintendent instructed first-shift operators at the WWTP to increase the rate of liquid chlorine supplied to the wastewater.  After an hour or two passed, and an artificially high level of chlorine was fully mixed into wastewater, they ordered the WWTP’s first-shift operators to use hand-held colorimeters to gauge the levels of chlorine.  Only when the colorimeter “maxed out” would the Superintendent take a sample for fecal coliform bacteria or E. coli.  This fraudulent procedure allowed for the chlorine in the wastewater to reach sufficient concentrations to avoid showing elevated levels of fecal coliform bacteria or E. coli, which would violate the WWTP’s CWA permits.  The WWTP never reported any exceedances of its CWA permit limits for bacteria or residual chlorine after July 2012.

The liquid chlorine rate was increased from about 2.5 gallons per hour, to somewhere between 70 to 120 gallons per hour, for up to two hours.  On non-testing days, WWTP employees maintained the chlorine feed rate at minimal levels, well below the designed feed rate of the WWTP and at a rate clearly insufficient to ensure the WWTP consistently and adequately disinfected its wastewater, as the WWTP’s CWA permits required.  The engineering firm that designed the liquid chlorine feed system at the WWTP estimated that approximately 16.7 gallons of chlorine would need to be fed per hour to properly kill bacteria.

Then, in the afternoon on fecal coliform bacteria or E. coli testing days, well after the high amounts of chlorine had dissipated from the WWTP’s chlorine contact basin, and when an insufficiently low rate of liquid chlorine was supplied to the basin, Schwarte and the Superintendent would test again for TRC.  In the afternoon, they were certain the TRC would pass, because only a minimal rate of liquid chlorine was supplied to the chlorine contact basin at that time.  Again, this minimal rate was clearly insufficient to ensure the WWTP consistently and adequately disinfected its wastewater, as required.

The WWTP was also not operated or maintained in good working order, which also violated the WWTP’s permit.  For example, the WWTP’s computer system was not only insufficiently connected and inadequately programmed to work with the various parts of the WWTP, but also it worked only intermittently.  Although the WWTP was designed to have two operational chlorine contact basins, for years the City operated the WWTP with only one operational chlorine contact basin.  Because both chlorine contact basin gates were “old and very leaky,” as reflected in an engineering report provided to the City in April 2012, wastewater constantly poured into the “offline” chlorine contact basin and later, out of the “offline” chlorine contact basin and into the Missouri River.

Schwarte was sentenced in Sioux City by United States District Court Chief Judge Leonard T. Strand.  Schwarte was sentenced to two years of probation, including two months of home confinement, and fined $5,000. 

“Patrick Schwarte intentionally cheated on environmental tests, knowing he was violating the Sioux City Wastewater Treatment Plant’s environmental permit and polluting the Missouri River,” said United States Attorney Peter E. Deegan, Jr.  “By doing so, he put recreational users at risk and endangered the river’s aquatic life.  This blatant disregard for the law and reprehensible treatment of one of our nation’s treasured waterways was nothing short of outrageous.”

The case was prosecuted by Assistant United States Attorneys Timothy L. Vavricek and Matthew J. Cole and investigated by the Environmental Protection Agency, Criminal Investigation Division, the Environmental Protection Agency, Office of Inspector General, and the Federal Bureau of Investigation. 

Court file information at

The case file number is 19-CR-4001.

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Updated November 9, 2020

Public Corruption