We tested the Wensum for human waste - this is what we found
- Credit: Sonya Duncan
Water in the protected river Wensum has high levels of bacteria found in human and animal excrement, according to tests carried out by this newspaper.
Our reporter took a sample at Carrow Bridge and sent it to a lab for testing. Scientists found high readings of a type of bacteria contained in mammal waste called coliform, the most common of which is E.Coli.
The sample had a reading of 4,800 colony forming units (cfu) per 100ml of water. There is no legal limit for the amount of coliforms in rivers in the UK but in other countries such as New Zealand and India, limits range from 2,500 cfu to 4,000 cfu.
When it came to E.Coli we found 1,400 cfu/100ml. Anything above 900 is deemed “poor” under the UK's Bathing Water Directive.
We also found a second type of bacteria contained in mammal excrement called Intestinal enterococci. A reading of more than 330 cfu/100ml is classified as poor. Our reading was more than twice that at 670 cfu/100ml.
An Anglian Water spokesman said coliforms were “natural” in waters and therefore they were not shocked by the findings.
The biggest causes of pollution in our rivers, according to the Environment Agency, are agriculture and water companies discharging untreated sewage.
In October we reported how sewage was poured into the region's rivers and sea 4000 times last year through storm overflow drains run by Anglian Water.
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The drains are used by water companies during heavy rainfall but figures showed they were being used the equivalent of 10 times a day last year.
The situation was particularly bad in Norwich with drains located on the Wensum pouring out the most raw sewage.
At Bishopsbridge Road, Elm Hill, Riverside Road and Chalk Hill Road drains had a combined 720 sewage spills, lasting for 12,000 hours in 2020. That is equivalent to a continuous flow of waste into the Wensum every minute for 18 months.
However, the city council is hoping to attract more people to use the river through its River Wensum Strategy.
It wants more people to paddleboard on the water and last week cabinet member Mike Stonard said: "I feel the river has been an underused asset for some time and we could really one it up for that type of use."
But our tests show the river is not safe to swim in.
Anglian Water deflected responsibility for the high readings in our samples, saying it had not discharged raw sewage from its nearest storm drains upstream or downstream of where our reading was taken in the 48 hours beforehand.
But Green Party councillor Ben Price attacked the water company for not doing enough to upgrade drains in the city.
“I am shocked but not surprised by these test results,” he said. “I’ve seen no evidence of climate adaptation planning and sadly the city council’s river Wensum strategy fails to take a leadership role on the issue.
“Climate induced extreme rain and flooding events will only become more commonplace, meaning the situation will only get worse, putting river users and this finely balanced ecosystem at unacceptable risk.”
Dr Richard Cooper, from the UEA’s school of environmental sciences, said coliforms were a good indicator of human and animal waste.
He described our readings as "high" and added: "I would expect to see lower readings than this in the winter as there has been a lot of rain to dilute the sewage. Usually, you get higher readings in the summer after heavy rainfall."
Dr Cooper said the government needed to tighten regulations which allow water companies to put sewage into our waterways. He also called on the Environment Agency to carry out more testing of the river for coliforms.
“There is nothing really to stop this pollution," he said. "It is being caused by continued housing developments and growing populations. The sewage system, which was built decades ago, just can’t cope so we are seeing water companies put more untreated sewage into the rivers.
“Anglian Water has upgraded a lot of their treatment works but the population pressure means more sewage is going through.”
He said it had a knock-on impact on wildlife and fish as well as the cleanliness of water in coastal areas where people swim.
A spokesman from Anglian Water said of coliforms: “They grow in vegetation and are found in bird and fish waste too, so it’s unsurprising that your samples showed high levels."
A spokesman for the Environment Agency said: “We all have a part to play in protecting our rivers, as climate change and population growth are putting pressure on waterways.
“The Environment Agency works with government, business and others to meet the challenge brought by extreme weather, which can have an effect of water quality.
“Anyone who suspects a reduction in the quality of our rivers, canals and streams should contact our free, 24-hour incident hotline: 0800 807060.”
Protecting the Wensum
The whole of the river Wensum is designated as a Site of Special Scientific Interest (SSSI). That means it has legal protection for its wildlife.
However, that does not stop untreated sewage being dumped into it or animal waste from farming - the two biggest causes of pollution.
But both Anglian Water and farmers have deflected the blame. In the upper parts of the Wensum valley samples collected by farmers show, they claim, that agriculture's contribution to the pollution is not as high as national figures suggest.
The chalk river had more sewage spills than any other river in the region last year, according to figures from the the Environment Agency.
Its ecological status is ranked as "moderate" by the agency.
- Additional reporting by Joel Adams
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