The Glebe Mining lagoon flooded into water at Stoney Middleton and Calver in January last year and the EA's latest findings – revealed at an update meeting at the Peak Park authority's offices in Bakewell last Wednesday – said that there was no short-term harm to wildlife or health.

But the Anglers Conservation Association's report claimed to have discovered heavy metals in sediment found at Stoke Brook, and the group criticised delays in remediation work.

ACA solicitor Justin Neal said: "We're pleased remediation has been carried out but there remains the risk of an effect on fish due to a presence of heavy metals.

"The EA will continue monitoring and we'll be considering civil action against Glebe Mining due to potential harm to fish and loss to members."

ACA launched its study after claiming EA sampling was limited and criticised the time Glebe, of Cavendish Mill, Stoney Middleton, took before starting remediation in June.

The study found heavy metals in the food chain and ACA believes these exceed safe limits for human consumption.

Ecologist and angler Dr Steve Furness, of Calver, said: "Heavy metals appear to be entering the food chain and we're worried about the future.Effects may have yet to be seen, which is why it's important the EA keeps testing vigorously."

Glebe, which mines minerals for the metallurgical industry, and the EA argued meticulous planning was necessary because of the size of the area and wildlife and long-term impacts could not be evaluated yet.

EA spokesman Lyn Fraley said: "There is still three-to-five-year monitoring in place and the only thing we altered due to the ACA study was to consider samples involving bullhead fish.

"But the short term conclusion is there is no harm to either wildlife or health."

Glebe general manager Gary Goodyear said: "We believe the system has been cleaned to a high standard and it's too early to comment on legal proceedings."