Shocking levels of damaging phosphates have been found in one of the Midlands' biggest rivers, as chemicals washed in from farmland and other waste combine to create a potentially deadly cocktail of pollution.
In fact, people who use the River Wye through Herefordshire say they're already seeing plant, fish and bird life dying off - a problem which experts warn is contributing to a “global crisis” for our waterways.
“I started fishing this river back in the 1970s, and you could catch salmon every time you’d come down, two or three in a go, and big ones,” keen angler Jonathan Daniels told us.
“And over the years it’s declined, and now there’s very little left. I fear for it, I really do.
“This river is full of sewage, and it’s ruining it - it’s killing all the fish. And it’s killing birds - there used to be thousands of swans on the river, but look at it now. They’re all gone. Because we find them dead on the river banks, poisoned or starved."
He’s a member of the Ross-on-Wye Angling Club, which for the few months has been monitoring phosphate levels in the water there.
It began in July last year, after they noticed an unusually high level of algae - and together with the Wye Salmon Association, they decided to investigate.
Fellow member Trevor Hyde has been the one taking samples on a weekly basis and testing them for phosphates.
He said he was shocked by what he found.
The phosphate limits along the Wye vary between 0.03 and 0.05 parts per million. So far, only three of the samples he took came in on target, with many coming in much higher.
Several samples have recorded levels five times that limit - a couple have been ten times higher.
“I wasn’t sure what I was going to find. Initially, I came at it with an open mind and I was astounded by the results I was getting, right from the off,” he said.
“It’s heartbreaking to be honest.”
Club chairman Rob Leather said members have reported a significant deterioration in recent years.
In 2016, he said, salmon fishers caught 44 between them. Last year, they caught two.
“It’s the algae, the phosphates, the gravel that the river is famous for - the river would normally be running clear. Instead it’s covered already in this brown slime,” he said.
“That will affect the eggs, they won’t have enough oxygen to survive. The lack of weeds will affect the bug life. So already you can see the eggs are going to have trouble, the fish are going to have trouble feeding, and so will the birds.
“And the danger is that it’s insidious - we see now there’s a few problems but it really won’t be noticed for maybe five years. But it’s real and it’s happening right now.”
Wild swimmers who frequent the Wye have reported a similar decline in water quality and wildlife.
Angela Jones can be found in the water there pretty much every day. She tells me the river “runs through [her] veins”, and she uses her swims to keep tabs on the underwater environment.
“In the last five years I’ve noticed a huge decline. I’ve been monitoring the fish, the salmon, the eels, and also I’ve been logging the water crow foot, which is an aquatic plant which lives in blankets over the Wye. And we’ve lost 95% of that over the last two years through pollution,” she said.
“I’ve brought attention to it, I’ve been videoing it, monitoring it, I’ve done magazine articles, newspaper articles, I’ve even painted myself green because of the amount of green algae from the phosphates which are washed off into the Wye.
“Last year, I spent a lot of time below the surface, monitoring and looking at salmon pools. I couldn’t even see below the surface because it was that poor, it was that green with algae.
“They need to address this, because there’s going to be a time when there’s no turning back. And I think we’ve reached that time now.”
Rob echoed her call to action.
“No one wants dirty rivers. No one wants to see this on their own doorstep, especially with the number of river users we get,” he said.
“The county gets five million visitors a year, and the river’s the life blood of the county and it’s why they come here. And that number will certainly go down if the river stays green and unhealthy.
“It’s astounding really. It’s enshrined in law. There are agencies out there supposed to be monitoring it, and then enforcing it. And it isn’t happening.”
And as ever when it comes to the environment, everything is connected. This is about more than just a few miles of river in Herefordshire - it’s threatening what experts warn is building up to a “global crisis”.
Phosphates which enter the water here will inevitably get carried downstream.
The Wye enters the Severn Esturary near Chepstow, on the Gloucestershire-South Wales border - a designated Site of Special Scientific Interest.
Any pollution in the Wye threatens the delicate ecosystem there, as well as the ocean at large.
Dr Peter Richardson, from Herefordshire-based charity the Marine Conservation Society, said: “We know that phosphates can have a really serious impact on marine wildlife and can contribute to ocean acidification so this is not just a local problem, this is a national, international problem, contributing to a global crisis.”
The Environment Agency told ITV News Central that it was aware of the problems along the Wye, but said currently they are focused on the exceptions in a different part of the county - a tributary to the River Lugg.
A spokesman said they were working with a number of parties, including Natural England and authorities in Wales, to address concerns - and warned that any breach of regulations found would be investigated, with enforcement action possible.
He added: "In Herefordshire, the issue is causing damage to a number of the county’s sensitive watercourses.
“We are targeting regulatory activity towards high risk areas and have reminded farmers that they are legally obliged to test soils and to prevent significant run-off.
“Any breach of the regulations may result in an investigation and enforcement action being considered.”