La Porte City has failed for years to adequately treat its wastewater to reduce bacteria and has routinely discharged it into a creek at levels that are hundreds of times higher than state limits, according to the Iowa Department of Natural Resources.

The DNR recently levied a $7,000 fine against the city for its delays in upgrading its wastewater treatment facility, according to a DNR order. The wastewater discharges into Wolf Creek, a tributary of the Cedar River.

The city was told five years ago to make a plan to update the facility and to have the work completed by January 2020, the order said. Specifically, the city had agreed to install a new treatment component that uses ultraviolet light to limit bacteria.

Tests in April of the wastewater leaving the facility found E. coli bacteria in concentrations of about 58,000 per deciliter. The limit is 126. The lowest average monthly concentrations in past tests have been about 16,000 viable organisms per deciliter.

“These are the levels that have been going into that stream for years,” said Amber Sauser, a DNR environmental specialist who is monitoring the situation.

The DNR tests for E. coli concentrations because the bacteria can irritate skin or infect people who come into contact with contaminated stream water. The tests are also used as a barometer for the presence of other bacteria in the wastewater. The DNR imposes the limits on La Porte City from March to November, when people are most likely to be on or near rivers and creeks.

The DNR issued a construction permit to La Porte City to upgrade the wastewater facility in 2019, but work was delayed when city leaders altered their plans.

The facility is about 35 years old and has had no major updates. It lacks the capacity to handle influxes of wastewater, especially during periods of flooding, said Clint Wienen, a senior project engineer for MSA Professional Services in Dubuque, which is designing the treatment plant upgrades. Groundwater is apparently leaching into the system.

“It’s hard to tell exactly where it’s coming from,” Wienen said. “It could be cracked pipes. It could be sump pumps that private residents have. It could be manholes that are underwater. There’s just a number of ways that it can get into the system.”

Wienen is working to finalize the estimated $7 million project, which is anticipated to start construction in about a year. The city will use grants and a state loan to pay for it, he said.

“Everything needed to be upgraded,” Wienen said, “but also there’s this additional flow component, which led to a different treatment process that can handle the higher flow.”