A major fish kill was prevented on Monday 15 July as a result of the Environment Agency’s fast response to a water quality issue on the River Delph at Welney.
Routine monitoring results showed a significant dip in dissolved oxygen levels in the river at Welney on Monday. Further testing by Environment Agency staff confirmed the issue which posed a significant threat to fish.
Water aerating equipment has been installed in the River Delph and teams continue to dose the water daily with hydrogen peroxide to increase dissolved oxygen levels and improve water quality for fish.
So far only a handful of fish have been reported dead.
Ian Hirst, Fisheries Team Leader at the Environment Agency, said: “This is a known problem which we monitor and respond to annually.
“Earlier this year we installed new water quality monitoring equipment which allows us to check the situation remotely in real-time – this meant we were able to respond as soon as water quality dropped.
“Our staff took immediate action, dosing the water with oxygen-enriching hydrogen peroxide to prevent a major fish kill.
“Without funds provided by anglers Rod Licence income the Environment Agency would not be able to respond to incidents of this nature in this way.”
The exceptionally hot weather is forecast to continue for the next week or so which is likely to exacerbate the situation. The Environment Agency is investigating further options to improve the water quality within the channel which might include transferring water in from other water courses, however, this solution comes with a number of considerations for navigation, abstraction and biodiversity.
The Environment Agency must balance the water needs of people, businesses (including agriculture) and the environment.
Different species of fish can tolerate different levels of dissolved oxygen, for example trout need a much higher water quality than pike but they all have limits and are harmed by rapid changes in the quality of the water.
The tell tale signs of fish in distress are fish gasping at the surface of the water or swimming on their sides or upside down.
Be vigilant, if you spot fish in distress call the Environment Agency incident hotline number 0800 80 70 60 with a clear description of what you witnessed and the location so that officers can investigate. Fish can often be saved if they are helped quickly.