I called the local Soil and Water office, where the woman said the fish kill was probably due to chemical run-off from a nearby field, and she suggested I call a fish biologist at the Department of Natural Resources, which I did. But he wasn't in his office, so I left a message, and of course he called back when I wasn't home. He spoke to my son and told him to call the EPA, which my son did. The person on the phone there said that someone would probably come out to investigate.
Today I realized that if the EPA put our address in a GPS system, they'd arrive at the pond down the road and leave because it looks lovely. (GPS doesn't know where we are.) So, I called the EPA this morning and had a lengthy conversation with someone who told me that they don't usually get involved in private pond problems unless there is evidence of definite pollution. So, he suggested I call the DNR. I told him that DNR had actually referred us to him, and he said that maybe DNR thought the EPA would be interested, but they're not, and the fish biologist at DNR would be our best bet in figuring out what happened. He said that most fish kills are due to oxygen deprivation, but he also gave me the name of a water testing lab in Peoria in case we wanted to check for the presence of chemicals in the water.
I emailed the water testing lab, and they said the fish kill was probably due to oxygen deprivation, but for a few hundred dollars they could test the water. So, I've spent the last few hours reading about fish kill and duckweed.
As you can see in the above photo, the surface of the pond is mostly green. It's not algae though. It's duckweed, which has never been a problem until this year. Apparently it can be spread by wild waterfowl visiting your pond and dropping off a plant or two, which can then multiply every single day! And before you know it, the surface of your pond is covered with duckweed. The good news is that it killed the algae because it doesn't allow any light to get into the pond. The bad news is that it's as bad for the fish as a huge algae bloom because it can ultimately reduce their oxygen and suffocate them.
So, we have one vote for poisoning and two votes for suffocation, and my reading is leading me to think that suffocation is probably the culprit. I did call the fish biologist again, however, and am waiting for him to call me back.
3 comments:
I feel your pain. We live in Southern IL (St. Louis Metro East). We have a 1.5 surface acre pond that has been covered with duckweed every summer since 2012. It disappears after a hard freeze, but returns in April and soon covers the entire pond. We have done a lot of research, and installed a $7000 aeration system in 2013, but results were less than satisfactory. We have explored the use of chemicals as a last resort (I know that is not an option you would choose), but the only effective herbicide for duckweed is exorbitantly expensive, and would require multiple treatments each season, and need to be repeated every season to assure the duckweed doesn't return. On the bright side for us, we still have abundant fish and wildlife. I don't know how the fish survive. We bought the property in 2009, primarily to enjoy the (then) crystal clear water views and access. Hope you can find some solution.
My Dad had the same thing happen 30 yrs ago, maybe longer. There was no pollution involved. He used the term "Turn Over" Apparently every 10-15, maybe 20, the water in the pond just "turns over" and a bunch of fish will die. Daddy explained it was a lack of oxygen that caused it to happen, and the conservation guy told him there wasn't a lot one could do about it. It was just a process. I'm sure there are more studies out there...so perhaps you will be able to find a better solution. Daddy was told it wouldn't be a problem for another 10-15 yrs...which, as far as I know, it never did it again.
I'm sorry---I know its such a shock...the last 2 winters, along with the massive rains we've had, has probably just turned everything on its end.
While I understand the concern about potential chemicals, looking at the duckweed on your pond, my vote goes to suffocation. I lost all of my very large goldfish overnight because of duckweed. That was in spite of a circulating pump. I was later told it is quite common, especially in hot weather. It was so hard to believe that literally every fish in my pond could die in just hours, but it happened. If you had been near the pond and noticed, you would have seen fish at the surface gasping for air as if they were an air-breathing animal suffocating.
So, until we find a solution to an overgrowth of duckweed or some way to control it, it is a fact of life and will happen again. I've not heard of some hungry duckweed-eating creature.
In my case it was doubly heartbreaking because of the nature of my fish. When I bought this house there were two very small goldfish in a filthy pond. We cleaned the pond, the fish grew and multiplied, showing their gratitude after years of neglect. I had all colors, literally, even "clear." I was still freshly grieving my youngest son's death and posted about the fish often in our support group and referred to them as my miracle fish. I compared them to ourselves, they start out dark and tiny and over time most grow into beautiful adults as they embrace life and thrive and we don't know what they will look like, gold, spotted, yellow, etc., but sadly some do not and never become the beautiful fish they can be. I spent many hours watching those fish and writing about them; the pond is right outside my dining room window so in a good place to give hope.
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