DNR finds more than 700,000 fish killed in East Nishnabotna spill

The investigation into the fish kill in the East Nishnabotna River has been completed.
The fertilizer spill in Red Oak in Montgomery County earlier this month killed nearly all the fish in an almost 50-mile stretch of the East Nishnabotna River to the Missouri border
On March 11, NEW Cooperative, Inc. in Red Oak notified the Iowa Department of Natural Resources (DNR) of a release occurring on-site. Approximately 1,500 tons (265,000 gallons) of liquid nitrogen fertilizer (32% solution) discharged into a drainage ditch, then into the East Nishnabotna River. The release occurred due to an aboveground storage tank valve left open for the weekend.
John Lorenzen is a fisheries biologist for the Iowa DNR. Lorenzen said he was called to begin his investigation early that afternoon.
“We reported to the call like we normally would, and didn’t respond to it any differently than we would for any other fish kill investigation. We just started flagging out survey transects at each bridge, working our way down river to where the kill was currently at,” Lorenzen said.
While not able to speak for everyone, Lorenzen said on a personal level, he hadn’t been involved in a fish kill of this size before.
“Personally, it’s the biggest fish kill I’ve ever been involved with. I can’t say that for all of the state personnel, however. It did impact approximately 50 miles of the East Nishnabotna in the state, and then it continued on into the state of Missouri where it flowed until it reached the Missouri River. It impacted fish the entire reach of the river, making it a long fish kill,” Lorenzen advised.
Water testing indicated nitrogen levels were 60 times higher than they should have been at the location where the spill occurred. When high levels of nitrite is in the water, it can cause fish to suffocate due to altering the fish’s ability to transport oxygen in its blood, but it this case, it was different. 
“It was such a large concentration that the fish succumbed to it from mere exposure. The toxic levels of the chemical were most likely killing tissue at the gills. It destroyed the cells and killed the fish due to acute toxicity,” Lorenzen explained.
In addition to fish, Lorenzen noted other impacted wildlife, though the survey Lorenzen uses focuses mainly on the fish population.
“We’re there to survey dead fish species and length. If we encounter amphibians, mussels, and things like that, we document them, but we’re specifically looking at fish. There is a different survey used to count mussels, as an example. There’s also a separate survey to evaluate turtles. We counted dead frogs, snakes, and mussels, but we by no means were able to do an extensive investigation into those types of animals,” Lorenzen commented.
While the fish kill was large, Lorenzen said it would have been worse had the spill happened a month or two from now.
“If this would have happened in late April or May, we’d have lost a lot more fish. A lot of the larger bodied river fish that people think of when they go to the river to fish, like channel catfish, blue catfish, flathead catfish, gar and walleye, those fish, for the most part, are still out in the Missouri river over wintering,” said Lorenzen. “They will move back up into our interior rivers, like the Nishnabotna, when water temperatures cue them to come up river. The Nishnabotna will warm up faster than the Missouri River. At certain temperatures, those fish will move up. They haven’t done that yet.”
Also, Lorenzen said the flows of the Nishnabotna are far less than normal due to the drought conditions, which helped preserve some fish, as higher flows could have cued fish to move up into the Nishnabotna as well.
Lorenzen said it’s difficult to anticipate what the wildlife response is going to be in the near future.
“I’m hopeful the fish will move up river as if nothing else has happened. The base forage will be much less, if not gone completely, but there are tributaries to the Nishnabotna that acted as refuges for fish, and those fish will help repopulate the river. The upper stretch above the kill were unaffected, and they will spread out and move downstream. I’m hopeful that the forage base will improve and the river repopulates with all these fish by next year. This year, it’s hard to say exactly how the fish will react with far less prey available,” Lorenzen advised.
As for the lasting impact, Lorenzen said even with the investigating done to now, it’s still too early to speculate.
“We’re going to do turtle surveys and see how it affected the turtle population. For years, we’ve had long-term turtle netting sampling that occurs on the East Nishnabotna north of Red Oak. We’re going to sample those sites and sample for turtles in the area where the spill occurred,” stated Lorenzen. “The turtles are still under the sediment at the bottom of the river this time of year. They don’t go into hibernation, but it’s something very similar. They have permeable skin and the oxygen they need through winter months moves through their skin and this is how they breathe during this time. We’re assuming they were susceptible to something like this, but we can’t inventory the population or what happened until later in the spring when the water temperatures are warmer. If those turtles ended up dying, they’ll float up out of the sediment when they bloat, and we’ll be able to tell then.”
Lorenzen remains hopeful that things will rebound and return to normal in a shorter time rather than a longer time.
On March 20, there was a fuel spill at an Atlantic Casey’s in Cass County that also flowed into the East Nishnabotna. While investigated by a separate division within DNR, Lorenzen said he wasn’t called in to investigate that scene.
“The Environmental Services Division are contacted by the public if they notice a spill or if the spill is self-reported. If ESD doesn’t see dead fish, myself and my office are not contacted. I was never called by ESD about the fuel spill in Atlantic, so as far as I’m aware, it was not at any level that caused fish to die.”
Officials with the DNR recommend anyone that has water wells near the river have their drinking water tested if they haven’t already. This service is free using Iowa’s Grants-to-Counties (GTC) program.
On March 28, the Iowa DNR issued a press release of Lorenzen’s investigation.
DNR Fisheries staff used methods outlined in American Fisheries Society, Special Publication 35, and 571 Iowa Administrative Code Chapter 113 to evaluate the extent of the fish kill and estimate the number of dead fish. The rules and the use of the American Fisheries Society’s methodology are authorized by Iowa Code section 481A.151.
The breakdown of the fish kill is as follows:
• Minnow Shiner Dace Chub: 707,871.
• Suckers: 1,542.
• Goldeye: 201.
• Common Carp: 9,255.
• Carpsucker: 14,500.
• Buffalo: Four.
• Sauger: 199.
• Channel Catfish: 7,681.
• Flathead Catfish: 264.
• Green Sunfish: 935.
• Silver Carp: 67.
• Largemouth Bass: 69.
• Grass Carp, diploid: 6,654.
Cleanup efforts at the NEW Cooperative facility are ongoing. Contaminated soils continue to be removed from the facility and from around a levee west of the facility. The contaminated soils will be land applied at approved locations, at agronomic rates consistent with Iowa law. Additionally, NEW Cooperative is pumping water from the east side of the levee. The pumped water will be stored in on-site holding tanks until land application can occur. A third-party consultant is collecting samples of the water-fertilizer mixture to determine accurate land application rates.
Per Iowa Code section 455B.186, a pollutant cannot be discharged into a river without a permit. DNR field staff are working with the DNR’s Legal Services Bureau to determine next steps with regards to enforcement action and restitution for lost aquatic life. The DNR will continue to monitor cleanup efforts.
Field test results indicate ammonia levels are declining in the river. The DNR continues to advise people to avoid recreating on the river and collecting and/or eating dead fish found on or near the river.
Officials with NEW Cooperative declined to make a statement.