MASON CITY – A fish kill taking place Saturday in a Mason City park is being caused by low oxygen levels also known as oxygen sag.
The fish kill was investigated by the Iowa Department of Natural Resources at Black Pit, a 16-acre pond in Lester Milligan Park on the southwest side of Mason City. Stressed fish of different species were observed on Friday with dead fish beginning to appear on Saturday. Water samples taken on Saturday indicated low oxygen levels.
The water at Black Pit is also currently experiencing an algae bloom. When algae blooms occur, the oxygen in the water can be greatly reduced causing fish kills.
