The two major mining-related events between 1998 and 2002 highlighted the very severe environmental impacts and huge economic costs.

The accidents occurred near the Doñana National Park in south-western Spain in April 1998 and in the Baia Mare region of northern Romania in January 2000.

On 25 April 1998, the dam storing waste water from mining operations by a Spanish subsidiary of the Canadian-Swedish Boliden company in Aznalcóllar breached and spilled around four million cubic metres of acid waters, as well as two million cubic metres of toxic mud, into the fluvial system of the Agrio and Guadiamar rivers.

The toxic flood inundated about 5 000 hectares of land near the watercourses (60 % crops and fields, 40 % pastures and river vegetation). While the mud accumulated in the first 40 km of the river, the acid water flowed 20 km further downstream. It was stopped by an emergency containment dam just before entering the National Park and then redirected to the Guadalquivir river. However, 98 hectares of the National Park were directly affected (0.19 % of its total area).

On 30 January 2000, almost 100 000 m3 of water polluted with high cyanide concentrations spilled out through a 25 metre break in the dam of a waste (or ‘tailings’) sedimentation pond at the mining company SC AURUL SA in the region of Baia Mare in north-western Romania. It was the beginning of one of Europe’s worst transboundary pollution incidents in recent years. The contaminated water flowed into an adjoining area of

around 20 hectares of agricultural land. Through drainage systems it reached the Lapus River and from there the Somes/Szamos, Tisza and Danube rivers before reaching the Black Sea.