The former Undertones lead singer and keen fly fisherman is taking on the water companies and Environment Agency

Feargal Sharkey, the former frontman of the Undertones, is not a man who is short of opinions. By the time we’ve walked a few hundred metres, he’s discussed the plight of journalism, the destructive monopoly capitalism of Google and Facebook, the state of the music industry and the irrepressible nature of British creativity.

But those are not the subjects I have come to talk to him about. We’re walking along the River Lea, one of southern England’s abundant chalk streams. There are, according to Wikipedia, 210 chalk streams in the world, and 160 of them are in England. Sharkey puts the figures slightly higher. The point is, though, according to this keen fly-fisherman, the large majority of them are in a parlous state.

As we walk along the Lea valley, heading south from Luton, he points to stretches of grey, stagnant-looking water. “I can tell you – it should not be grey,” he says. “It really shouldn’t.”

Sharkey has become something of an expert on chalk streams, and has his own impressive stream of facts and figures. They pour effortlessly from the famously inverted mouth that once sang the lyrics to such classics as Teenage Kicks and My Perfect Cousin, as well his own solo work, such as A Good Heart.

If southern England’s rivers flowed like Sharkey’s condemnation of their ecological regulation, then there wouldn’t be much of a problem. He talks about the various agencies tasked with overseeing the health of England’s rivers – the Thames Water Authority, the National Rivers Authority and finally the Environment Agency.

“In 42 years a bunch of bureaucrats have generated hundreds and thousands of pages of reports, models, hydrological studies, geological studies, fisheries studies and flow data. The last time I looked there were 39 separate reports about chalk streams in Hertfordshire alone. And yet only 14% of rivers in England reach good ecological standards. What the hell have they been getting up to for the last 42 years?”

The way he tells it – with a kind of breathless passion in his still-intact Derry accent – there has been a shocking lack of investment in infrastructure, while demand for water, particularly in southern England, has hugely increased.

“In the south of England,” he says, “we have not actually built a new reservoir since 1976.”

The result is that water companies are drawing supplies from rivers that can’t cope, leading to drying river beds. They are also using them to deal with excess sewage. He cites the example of Thames Water, which was last year fined £20m for spilling 1.9bn litres of untreated sewage into the Thames.

He says the water companies have been fined many times, although not at that scale. But as the judge noted in the Thames Water case, it’s often cheaper to offend than take the appropriate precautions. This is where Sharkey believes the Environment Agency has been far too soft on the water companies, allowing them to shirk their ecological responsibilities time and again.

Facebook Twitter Pinterest Sewage foam collecting around boats on the Thames. Photograph: Environment Agency/PA

Sharkey honed his disputing skills during his years in the music industry. After he quit performing, he worked for Polydor Records and later headed UK Music, which represented all sectors of the industry. He is now retired and spends a fair amount of his leisure time at Amwell Magna Fishery, Britain’s oldest angling club, some miles further down the Lea.

It’s based on a stretch of water that has been fiercely protected by the club from intruders, including the Ministry of Defence and the water agencies. The result is a pristine environment in which trout fishing is possible.

But this fishery is a rare exception. The norm is increasingly exhausted rivers with minimal flow and poor management. As we walk past the East Hyde sewage treatment works, whose sign reads “Hello and welcome”, Sharkey takes out his phone and shows me a flow gauge of the river. Its peaks and troughs correspond to treated sewage being pumped into it between 9am and 6pm each day.

“Guess what it does to the ecology of the river when you’re increasing the flow by six or seven times the normal amount every 12 hours? You destroy the river. Nothing can establish itself – not weeds, not invertebrates. Why can’t they drip-feed it over 24 hours?”

Suddenly I feel like I’m in a Home Counties version of Roman Polanski’s Chinatown, with murky goings on with the water company, and a dogged individual in the Jack Nicholson role, busy joining the dots. But the water companies are not the only people Sharkey blames. He says it’s estimated that 5% of homes in London are misplumbed, so that their waste goes into rivers rather than the sewage system. There’s one school in north London, he claims, that dumps 98,000 litres of effluent each day into a local river.

He is calling for a complete overhaul of the water regulation business, the building of more reservoirs, a national water plan – rather than separate companies looking after themselves – and a national distribution network.

It’s an ambitious list of demands but he says he’s hoping to get the ear of Michael Gove, the environment secretary, a man with a reputation for getting things done.

“Whether or not they’re the right things …” he adds dryly.

It would be a mistake to write Sharkey off as a former pop star with too much time on his hands. Now 60, he retains the youthful energy and gimlet-eyed focus of those explosive early Undertones performances. He’s got the bit between his teeth and he knows how to get access to powerful people.

“We can’t continue this decimation of 85% of the world’s chalk streams,” he insists. “They’re our Amazon rainforest. If it was some other country doing this, the UK would be at the bloody UN shouting and screaming.”

At the moment, it’s just Sharkey doing the shouting. But be warned, he’s got some voice.