Twenty years ago the streams of the upper Wye and Irfon catchment appeared to be in pristine condition. But taking a closer look would reveal they were lifeless – no fish, invertebrates, plant life or even slime on the stones.

This had been caused by an increase in the frequency and intensity of flushes of acidity flowing into them after rainfall. The result was devastating not just for fish but for the ecology of the whole area.

Read more about acidification, how it came about and what the Foundation and its partners have done to correct it.