The cause of the death of numerous fish at the pond in East Park is a mystery.
The City of El Dorado has investigating the cause after received the report of dead fish Wednesday.
After inspecting the pond, they found a lot of big and little fish dead.
"The first thing we did was start adding new water," said Herb Llewellyn, city manager. "The solution to pollution is dilution. We have been cleaning up and adding water ever since."
They first suspected it was due to waste from the geese and ducks, which had taken all the dissolved oxygen out of the water, but when they checked, there was a lot of oxygen.
"We then started looking for other things," Llewellyn said.
They have been in contact with Randy Just, from the El Dorado State Park, and Craig Johnson, Kansas Department of Wildlife, Parks and Tourism fisheries biologist for El Dorado, to try to determine the cause.
Kurt Bookout, public utilities director, said he had talked to Johnson and they both were stumped as to the cause.
“We’ve run all the tests we know to run in our lab and didn’t find a cause,” Bookout said.
He said they are continuing to flush fresh water through the pond.