MORE than 300 carp were rescued from a Fenland leisure park after salt water from the River Nene seeped underground into a fishing lake. But 200 fish were killed in the incident, at the Little Ranch Leisure Caravan Park at Begdale, near Wisbech. Environme

MORE than 300 carp were rescued from a Fenland leisure park after salt water from the River Nene seeped underground into a fishing lake.

But 200 fish were killed in the incident, at the Little Ranch Leisure Caravan Park at Begdale, near Wisbech.

Environment Agency fisheries officers were called to the leisure park on Friday evening, after reports of fish dead in the lake.

A water sample taken from the lake for chemical analysis found high salinity levels, which can lead to the presence of the alga, Prymnesium, which can produce a toxin lethal to fish.

Paul Wilkanowski, ecological appraisal officer for the Environment Agency, said: "Acting quickly was key to preventing the death of more fish in Begdale and we were able to identify the cause of this incident very quickly."

A spokeswoman for the Environment Agency said the lake's proximity to the estuary of the River Nene, which runs through Wisbech, meant water could seep through the ground and into the lake.

She added: "A certain amount of salt in the lake combined with certain weather conditions can lead to the algae."

The lake was dosed with hydrogen peroxide to kill the alga and prevent any further release of toxins. Further tests a few days later showed that the Prymnesium was killed by the chemical.

The live carp were temporarily re-homed in a nearby leisure park swimming pool and have been returned to the lake. Discussions are ongoing about the reopening of the lake for fishing.

Mr Wilkanowski said: "Anyone who sees dead fish, fish in distress, or pollution in our rivers and streams should call our emergency hotline number as soon as you can.

"In this case, it was the swift action of our officers that saved the carp, but the story could very easily have been different."

• Environment Agency emergency hotline number: 0800 80 70 60.