As with air quality, this is in part because of regulatory restrictions on emissions. However, levels of phosphorus and nitrogen may still be higher than is desirable in certain areas. One reason for this is subsidies to agriculture, which encourage the overuse of nitrogen and phosphorus fertilisers. Water use in Britain has declined whilst availability remains roughly constant. This is largely a result of the privatisation of water companies, which led to charging for each unit of water supplied to all commercial and some domestic customers, creating price incentives to conserve water.
Forests can provide habitat for numerous species of plant and animal.
The total area of forested land in Britain grew by a third from 1.8 million hectares in 1970 to 2.4 million hectares in 1995. They include marshes, swamps, and bogs. In Canada and the US, the area of wetlands has remained stable since the mid-1980s at 13 million and 1.2 million hectares respectively. In the UK, the area of wetlands increased by about 6 per cent between 1984 and 1990 to around 300,000 hectares. When precipitation levels exceed the soil's capacity to absorb water, soil and soil nutrients are carried away in streams and gullies.