Clogged line led to massive fertilizer spill to East Nishnabotna River

A farmers’ co-op employee left open a valve on a clogged fertilizer line that — for an unknown reason — became unclogged when no one was present and heavily polluted the East Nishnabotna River in March, according to the Iowa Department of Natural Resources.

The spill at NEW Cooperative in Red Oak happened over a weekend from March 9 to 11, until it was discovered that Monday morning by co-op employees who were starting their work week.

It leaked about 265,000 gallons of liquid nitrogen fertilizer that flowed through a stormwater ditch, under a levee and into the nearby river, where it killed almost all the fish and other aquatic creatures downstream for about 60 miles.

It was among the worst river contaminations in the state’s history and was so potent that its deadly effects on aquatic life only ceased when it reached the Missouri River and was diluted by that river’s significantly larger water flows.

The co-op has attributed the spill to an error by one of its workers but has declined to publicly comment further.

The DNR is awaiting more information about the incident and the company’s response to it, said Brent Martens, an environmental specialist for the department.

The department will ask the state’s Environmental Protection Commission this month to refer the matter to the state attorney general’s office for enhanced enforcement in district court, Martens said. The DNR’s administrative fines are capped at a maximum of $10,000, and the attorney general could seek much more.

A clogged pipe

The spilled fertilizer had been stored in a 500,000-gallon tank that has barriers around it to prevent a leak from spreading, according to an investigative report Martens compiled.

It typically flows through a pipe to a nearby building to be distributed to trucks for transport that has no similar barriers.

But that pipe had developed a crystalline blockage before the spill, and an employee apparently left its valve open, Martens said.

Parts of the fertilizer — a urea ammonium nitrate solution that is 32% nitrogen and commonly known as UAN-32 — can crystallize during cold winter months. That material has the potential to block distribution lines.

The blockage in the NEW Cooperative line is believed to have dissipated when no one was at the distribution site and allowed fertilizer to flow out of the open valve.

The fertilizer went over land and through a stormwater drain into a ditch that goes to the river.

The spill was discovered by co-op workers about 5:30 a.m. on March 11, according to Martens’ report. They used soil to block the ditch and stop further contamination of the river.

But the damage had been done: The fertilizer plume killed more than 750,000 fish in Iowa and Missouri, conservation officers estimated.

They also noted dead frogs, mussels and snakes and are waiting to learn whether turtles that buried themselves in the river bottom over winter survived.

The cleanup continues

NEW Cooperative, which is based in Fort Dodge and has numerous locations in the western half of Iowa, hired a company to remove contaminated soil from the area, and the work is ongoing.

Martens said the decontamination has been slowed by repeated rainfall in recent weeks. The co-op is expected to provide a report that details how the spill happened and what the co-op did to remedy it when the work is finished.

The state Environmental Protection Commission is expected to take up the issue at its May 22 meeting and vote whether to refer it to the attorney general’s office — an uncommon request that is usually reserved for the most egregious environmental violations.

The commission’s last biennial report — which covered its actions from July 2020 to June 2022 — said it asked the attorney general to intervene in three cases of improper solid waste disposal during that time frame.

A NEW Cooperative spokesperson did not immediately respond to a request to comment about the potential referral.

It’s unclear what the state might seek, but restitution for the dead fish — which is often one component of the penalty — was estimated to total more than $200,000.