Posted on

Perhaps the most well-known issue affecting the water environment is pollution. Pollution can threaten the quality of all categories of water and during all parts of the water cycle. Pollution means that there is too much of a material (a pollutant) in the water that is harmful to water quality or aquatic plants or animals. A pollutant can be anything from a poisonous metal or pesticide to a nutrient which can choke waters with excessive plant growth, or even silt that can smother fish spawning beds.

Pollution comes from one of two types of sources:

  • Point sources, e.g. pipes discharging effluent from industrial sites, wastewater treatment plants or mines
  • Widespread sources (diffuse pollution), e.g. land use activities such as farming, forestry and urban areas

Point source pollution

Point source pollution refers to contaminants that enter a waterway from a single, identifiable source, such as a pipe or ditch. A way to remember what point source pollution is that you can point to where the pollution came from. There are many sources of point source pollution and incidents occur frequently throughout the Ribble catchment.

In rural areas, point source pollution may come from a leaking slurry tank or a faulty septic tank. Disposals to land, including waste sheep dip and pesticides, which cause groundwater pollution are also classed as point source pollution.

Sewage disposal is a long-standing source of pollution. The most serious problems are now associated with sewers, which often date back to Victorian times. During heavy rain these sewers overflow into rivers, causing pollution. During prolonged periods of heavy rain, some sewers back up and contribute to flooding of urban areas. Industrial discharge is also a major issue, especially during low flows when there is less water to dilute it.

Diffuse pollution

Diffuse pollution is pollution arising from rural and urban land-use activities spread across a catchment or sub-catchment. The sources are heavily influenced by rainfall and can be individually minor but collectively significant.

In rural areas, diffuse pollution comes from a range of land use activities including agriculture, forestry and mining, and areas maintained for recreational purposes such as parks, green spaces and golf courses. Septic tanks from individual dwellings or small clusters of properties can also contribute.

Diffuse agricultural pollution arises from land-use activities such as livestock grazing and cultivation of land to grow crops and from farm steading run-off. Such activities can give rise to a release of potential pollutants which individually may not have an impact but together, at the scale of a river catchment, can impact on water quality. Much of this pollution is unintentional and good agricultural practice can help address the problem.

The pollutants are transported to waters by a number of recognised routes. As a result, both land use and run-off management are important in the control of diffuse agricultural pollution.

The rain falling upon urban or built areas (roads, pavements, yards and roofs) creates polluted run-off. Frequently, this run-off drains to surface water drains which pass directly to the water environment. This type of pollution is toxic, creating an oily film on the bed of rivers killing fish and the insects that live in the rivers.

Many people are unaware of the type of drainage system serving their home or work place. Pollution can occur when chemicals, waste oil or other polluting materials are illegally disposed of ‘down the drain’ directly into watercourses (albeit often without an intent to cause pollution).

If you notice a pollution incident on any part of the Ribble Catchment, please call the Environment Agency incident hotline on 0800 80 70 60 at any time.