You should read TFA. Among it's many unambiguous claims is that the root cause was extensive dumping at Morgans Farm by Robins of Herstmonceux, and that fixing it could be model for how to fix similar problems throughout Britain.
I do not, in fact, see such an unambiguous, unhedged claim in OP. Can you quote it?
An unhedged claim can't be quoted because there isn't one, but nobody claimed otherwise. Absolutist claims are, of course, an unrealistic bar for journalism. It's unclear why you are writing ominously/non-colloquially. I'm guessing you have some kind of unstated bias here, and are falling into the internet trope of speaking as though something doesn't even exist unless it is proven in a court of law or via formal math or something.
What on earth are you even referring to? Everything written in the article seems relevant. Isn't the claim that this entire lake was killed due to negligent pollution from an upstream farm, and is one of many cases? Isn't the conclusion that these cases are caused by a lack of regulation/enforcement?
Did you even read it? It's a pretty deep dive yes, but it does have some real background and makes clear claims on what is going on.
I guess I was hoping for concrete evidence, charges brought and consequences. Given the length of the read I'd wanted some payoff...
Yes I found there was some suspicion. The rest read to me as related thematic padding.