MASON CITY, Iowa - Imagine walking along a trail in a wooded area, you look down at a hole in the ground, and see water that's as white as milk.
That's what walkers found Wednesday morning along an unpaved path near the Mason City Industrial Park. Iowa DNR was called in to investigate it, and an investigation traced the mysterious color from an organic milkshake ingredient that spilled inside the nearby Martin-Brower facility, which is a McDonald's distribution center, on Monday. The ingredient that was spilled was hosed into a storm drain that ended up in a plunge pool along the path, and into part of a tributary. A contractor quickly arrived on scene to pump out about 6,000 gallons of the discolored water and any residual water remaining. None of the discolored water ended up downstream in Black Pit.
While water sample tests showed dissolved oxygen and normal pH levels, Supervisor Trent Lambert says there is still a bit of concern when the ingredient breaks down and dissolves over time.
"It takes oxygen to help complete that process. What it would do is pull the dissolved oxygen out of the water, leaving any fish, any aquatic invertebrates, they would suffocate and die. There's always that possibility."
Fortunately, there wasn't enough water in the tributary to carry it downstream, making it easier to clean up.
"Had we been in a typical spring situation with frequent rainfall and a lot of water running through storm sewers, the volume and velocity would've been much higher in the creek, and it may have got there before we could've got to it to clean it up."
Lambert advises people to avoid dumping into streams and ponds.
"A lot of times, when we think of storm sewer, is what we call it. But it does not mean it goes to the sewer treatment plant. Only the sanitary sewer does that. Your storm sewer or storm drain is going to go to a surface water. If you're not sure where that drain goes, we shouldn't be dumping anything in there. Be it paint, any kind of fuel, even chlorinated water from a swimming pool."
Iowa DNR continues to monitor the situation, and the investigation is ongoing. Lambert says it's likely that Martin-Brower will be cited for an illegal discharge, but that's not going to typically entail steps like fines or sanctions, as they believe the discharge was accidental, and that Martin-Brower responded to it quickly.
In Western Iowa, the DNR is investigating two manure spills that have killed fish in Lyon and Kossuth Counties.