Restoring the damage
Lakes and rivers can have powdered limestone added to them to neutralise the pH of the water - this is called "liming". Liming, however, is expensive and its effects are only temporary - it needs to be continued until acid rain stops. The people of Norway and Sweden have successfully used liming to help restore lakes and streams in their countries.
A major liming programme took place in Wales where 12,000 km of its waterways were acidified. In 2003 liming of the river Wye led to a return of the salmon which had completely disappeared in 1985. However, other parts have taken longer to recover and there are still no signs of life.
Recently a more positive side of acid rain has been noted as it can be very effective at reducing the natural production of methane, a “greenhouse gas” approximately 23 times more powerful than carbon dioxide, especially in wetland areas. The sulphur in acid rain limits the activity of methane-producing microbes found in wetland areas. (New Scientist)