Various health advisory signs, pictured July 3, 2017, were posted around a creek just west of Monterey Way between Sixth and Eighth Street where unauthorized dumping of used cooking grease was discovered.

Whoever illegally dumped several thousand gallons of cooking grease into a city manhole has yet to be held accountable.

It has been six months since someone dumped the grease, which contaminated the city’s storm sewer system, nearby waterways and resulted in a dayslong cleanup for the city.

Lawrence Police Sgt. Amy Rhoads told the Journal-World this week that the grease-dumping incident is no longer an active investigation.

“(It) does not appear there are any current leads being investigated,” Rhoads said in an email. “Certainly, if anyone has any new information related to the grease dumping or suspect identification, we would encourage them to contact us.”

The grease was dumped into a manhole near the intersection of West Sixth Street and Monterey Way. The manhole is between Hy-Vee grocery store and a strip mall with several businesses.

Following the dumping, city engineers told the Journal-World that the city had to hire plumbers to clean the city sewer lines; a hazardous materials cleanup crew to decontaminate a nearby creek; and a septic service to collect runoff from the cleaning.

The Journal-World has requested, but not yet received, an estimate from the city of the total cost of the cleanup, which will likely include the cost of the contracted services as well as city staff time.

Dumping oil of any kind is illegal under federal law and city ordinances that regulate pollutants. Cooking grease (both animal fat and vegetable oil) is as damaging to the environment as petroleum oil, according to the Environmental Protection Agency. Businesses are required to collect cooking grease and dispose of it properly, and they typically pay outside companies to perform the task.