Dallas County Diesel Spill Spurs Felony Charges and $100K Cleanup Effort

DALLAS COUNTY, Iowa — A criminal investigation is underway after a massive diesel spill on a Dallas County farm contaminated soil, water, and nearby ecosystems, prompting a multi-agency emergency response and felony charges against a former employee.

The incident occurred early Saturday morning when an above-ground storage tank on a farm near Dallas Center began leaking, ultimately releasing approximately 4,000 gallons of diesel fuel into the environment. The fuel trickled from the tank into a nearby pond and then traveled further, reaching Little Walnut Creek, a tributary vital to the local ecosystem.

Although Iowa Department of Natural Resources (DNR) officials were able to contain the spill with absorbent booms before it reached broader waterways, the environmental impact has been severe. The contamination prompted immediate public concern, with residents in nearby Waukee reporting a strong odor of diesel fuel emanating from the creek area. Authorities quickly advised the public to avoid contact with the water, although they noted there is currently no known health threat. No fish kills have been observed, but monitoring continues.

The Dallas County Sheriff’s Office announced Wednesday that 36-year-old Aaron Wayne Peek of Des Moines has been arrested in connection with the spill. Peek, a former employee of the affected farm—Manning Ag—was charged with first-degree theft, first-degree criminal mischief (both felonies), and trespassing. According to investigators, surveillance footage and witness statements confirmed that Peek intentionally caused the leak, leading to extensive environmental and financial damage.

Joe Manning, whose family owns and operates the farm, expressed his disbelief following the arrest. “As of March 31, I never heard from Aaron. He left here, and I haven’t talked to him since,” Manning said. “I don't know if he was upset or had other things going on in his life and wanted to retaliate with us or someone at Manning Ag.”

Cleanup crews have since been working around the clock to mitigate the damage. Diesel fuel has been found up to three feet beneath the surface of the affected site, requiring extensive soil removal and water treatment. The total estimated cost of the cleanup has already exceeded $100,000, with additional remediation efforts likely to continue for weeks or even months.

The Iowa DNR is continuing to monitor the site and assess long-term environmental impacts. The case has sparked renewed calls for better safeguards on agricultural fuel storage, including enhanced security measures and stricter oversight of former employees with access to sensitive infrastructure.