IT came to represent the rural idyll of an unspoilt Ireland for millions around the globe, but the real-life river featured in the TV programme Ballykissangel hides a dark secret that the tourist brochures tend not to talk about. While characters were seen panning for gold in the fictional Angel river, its real-life counterpart, the Avoca, is the most polluted in Ireland.

Avoca became a tourist mecca due to the popularity of the BBC series, but unknown to visitors, the stretch of river running under the bridge is almost lifeless. According to EPA figures, it is the most polluted stretch of inland waterway in the country.

The pollution is directly attributable to the now-closed Avoca copper mines, just over a mile upstream from the village. The copper reacts with rainwater to create acidic effluent, which then leaks through groundwater into the river from open fissures. As a result, part of the famous river is almost lifeless because of the high acidity levels. However, the Eastern Regional Fisheries Board (ERFB) now hopes to address the problem and rehabilitate the river.

"It's a 250-year-old problem, " says the ERFB's Josie Meehan, project leader in charge of plans to rehabilitate the river. "The mines have been operating since that time and we have letters from nearly 100 years ago complaining about the problem." The board has commissioned a study by experts from Newcastle university, who are due to report later this month with a series of recommendations.

However, fixing the problem will cost millions and the state is likely to have to foot the bill as the mines are in receivership.