Hundreds of fish in a city centre river are believed to have died as a result of the recent heatwave and contamination from drainage water. Residents and wild swimmers were horrified to find them washed up on Saturday, appearing to gasp for air, in the River Wensum through Norwich.
Lucy Galvin, the city council leader, said she and other residents had noticed dead pike, carp, roach, eel, rudd and dace. Local river campaigner Sarah Eglington said the scenes were "absolutely heartbreaking".
The Environment Agency said it believed the incident was the result of the recent heatwave - ultimately depleting the river's oxygen - and because heavy rainfall on Thursday had likely flushed in contamination from surface water drainage systems. A spokesperson explained that high temperatures created the conditions that "significantly" reduced dissolved oxygen levels in the water.
What did residents see at the river?
Residents and wild swimmers said they were shocked by the number of dead fish at the River Wensum through Norwich on Saturday. The fish were reported to have been washed up and appeared to be gasping for air, prompting concern among those using the river.
Eglington, who is from the Wensum Riverkin group, which campaigns for better maintenance of the river, said the water had seemed "beautiful" when she swam there with her son on Wednesday. She said "you wouldn't recognise" it was the same river.
"I can't quite believe what I'm seeing. It's absolutely heartbreaking."
Green Party city council leader Lucy Galvin said she was "absolutely devastated" by what she had seen when visiting the river at Cow Tower.
She said she and other residents had noticed dead pike, carp, roach, eel, rudd and dace. "What we are seeing are the effects of climate change and it is catastrophic," said Galvin.
"What we are seeing are the effects of climate change and it is catastrophic,"
Why do officials believe the fish died?
The Environment Agency said it believed the recent heatwave had depleted oxygen in the river, while heavy rainfall on Thursday had likely flushed contamination from surface water drainage systems into the River Wensum. The agency said its officer "promptly attended the scene" and that its investigation concluded the most likely cause was contamination from surface water drainage systems combined with low river flows and high temperatures.
A spokesperson said the high temperatures created the conditions that "significantly" reduced dissolved oxygen levels in the water. The agency said:
"The most likely cause of the incident was heavy rainfall on Thursday evening flushing contamination from surface water drainage systems into the river."
"This has coincided with a period of low river flows and high temperatures, creating conditions that significantly reduced dissolved oxygen levels in the water."
It said it would continue to monitor the river and work with partner organisations.
How important is the River Wensum?
The River Wensum stretches about 44 miles (71km) through Norfolk and is designated as a Site of Special Scientific Interest and Special Area of Conservation. It is believed to be home to more than 100 plant species and rich invertebrate fauna, and is recognised as one of the most important chalk river habitats in England.
Rose, 24, is part of swimming group Cow Tower Dippers, which meets at the river most weekends. She said:
"It's never been like this, it is devastating."
Rose said she had been coming to the river for the past year and had never seen anything like this before.
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