When the oxygen level of a lake is zero, that water, for practical purposes, is dead. Certainly all aquatic organisms in water having less than 1 milligram per liter of dissolved oxygen perish.
You know that water behind my house I call the duck pond? Sometimes I write about it or share pictures of the ducks and egrets there. The Environmental Protection Agency says it may have been contaminated by a truck spill. So they posted a warning sign (photo below) there and at other sites along the Kishwaukee River system.
We know the water is unhealthy because the EPA tested it on July 31, after reports of hundreds of dead fish, and found no oxygen in some areas. The disaster was featured on the news. The cause for the die-off is traced back to a July 25 semi tractor-trailer accident on nearby Illinois Tollway 90. My husband and I saw the smoke and flames from that truck accident, but we didn’t realize that the truck was spilling a concrete curing agent called Ethoxylated C10-16 Alcohol into the ditch.
Huntley water contaminated
Below is a photo I took of the truck on fire two weeks ago. I-90 is under construction and you can see a ditch with water in the foreground. On July 29, Illinois EPA’s Office of Emergency Response started investigating the source of the water contamination. An environmental consultant for the trucking company involved in the accident disposed of the dead fish, sucked up some of the pollution, and sent water samples to a lab in Singapore. The trucking company received a violation notice from EPA.
The Kishwaukee River system includes our duck pond and local lake. We don’t know yet the full extent of the contamination. We’ll see what happens. I hope our water comes back to life.
I miss the egrets.
Egret on the “duck pond” before the contamination
OF THE EARTH by Barbara Terao 
How sad to think that this egret cannot yet return to this lovely native pond. How is the clean up progressing?
Hi, Clare! Most of the clean-up is complete and the warning signs by the water have been removed. Full recovery will take a while. We used to hear the croaking of frogs and now it is silent. Without the frogs and fish to eat, the egrets go elsewhere. For now.
Follow up? Have the egrets returned?
Thanks for asking, Bob! In the fall after the completion of the clean-up, we saw egrets back in the pond! Now that it’s winter, there are ducks and geese there. Hard to tell if there are any lasting effects of that specific contamination, but life in the Kishwaukee River system and wetlands seems to be back to what it was before the spill. (You know how I treasured the gorgeous white birds we saw in Florida, in your neck of the woods. So I do love seeing the Great White Egrets here.)