State blames organic matter for fish kill, professor agrees

Dead fish float in Sand Creek earlier this summer.

By Adam Strunk

The final report from the KDHE blames organic debris for Newton’s July 3 fish kill.

The KDHE report included lab testing of oxygen, nitrate and phosphorous testing, as well as visual observations from those charged to investigate the kill that left fish large and small dead in the creek.

The report concluded that a rain event pushed milo stalks, grass, limbs and other debris into the water. As the organic material decomposes, it can lower oxygen levels in the water, which eventually will kill fish.

Because the creek is damned and flows slowly, the KDHE report concluded it took a while to dilute the organic matter resulting in the kill.
“Dissolved oxygen readings were higher in sampling locations further north from the dam,” the report stated. “Dissolved oxygen readings continued to improve the week following the incident. Dissolved oxygen readings south of the dam remained higher throughout the event due to the aeration of the water over the dam.”

The report noted that oxygen levels in the water continued to improve as time passed from the event.

The reports also highlighted the differences in fish observed during the investigation. The closer to the dam they got the smaller the visible living fish became. The water was also a clear, but dark coffee color, indicating decomposing organic materials.

The report did test for nitrates and phosphorous but did not determine levels of either chemical played a role in the fish kill. The report does not test for additional chemicals, like pesticides present in the water.

Harvey County Now sent the testing results to Keith Gido, distinguished professor at Kansas State University’s Division of biology, for independent confirmation of the state’s conclusions.

He said that fish kills during flooding were not that unusual. Landscape where native grass has been plowed up for instance doesn’t hold back sediment and debris he explained.

“The low oxygen levels in the report < 4 mg/L are pretty low,” he said. “Fish kills typically occur when dissolved oxygen is < 2 mg/l, but different species can be more or less resistant. “

Gido said nothing odd stood out to him in the report. 

“The nitrogen values were high, but not atypical for streams that have agriculture fields upstream,” he said.

While the amount of dead fish were dramatic at the time, state reports did show plenty of fish were still alive and swimming in the creek the days after the event.

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