Low oxygen levels appear to be the cause of fish kill in Silver Creek, just below the Silver Lake dam spillway along Illinois Route 143 in Highland.
Hundreds of fish — catfish, carp and Asian carp — could be seen floating for several hundred yards below the spillway and also washed up on the creek’s banks.
When the kill occurred exactly is unclear. Some fish that had washed up on land had been reduced to skeletons. At the same time, some live fish could still be seen swimming in the creek waters below the dam.
Despite recent rains, the spillway, which serves as an overflow relief outlet when the 550-acre lake gets too high, has not had water flow over it in some time. That means no new water has flowed into Silver Creek, causing oxygen to get depleted in the standing water.
There were no reports of fish kills in Silver Lake itself.
Also, while there were Asian carp among the fish killed in the creek, that species has never been reported in Silver Lake itself.