Diffuse pollution from rural areas
This is pollution that comes from widespread activities and may enter water across an area not necessarily from a single point. For example nutrients entering a stream from a neighboring field. This can be directly toxic to all wildlife, however more often it causes a change to the eco system, resulting in an indirect loss of wildlife. Such as, additional nutrients causing explosive growth of algae and/or aquatic weed, this will choke the river and can cause available oxygen levels to crash at night killing fish and invertebrates, however it could be more subtle and just slightly reduce the available oxygen. This will reduce the numbers of fish and inverts that are supported by the stream, with knock on effects to other wildlife. Health Eco systems rely on abundance.
In rural areas this is mainly from agriculture, in the form of over applicated or in appropriately applicated fertilizers or pesticides, such as artificial nitrates, slurry or herbicide. There are strict guidelines on the application of all of these, however all to often these are ignored or the landowner will not realise this. Some sources and results of Diffuse rural pollution
What can you do?
Buy produce from local farmers and farmers markets (especially certified producers), as small producers generally are more environmentally friendly than the larger factory farms. Also try and by organic certified food.
If you see rivers or streams running with slurry, or dead fish report it to the Environment Agency on the Pollution Hotline 0800 80 70 60.