Diffuse pollution

Diffuse sources of pollution include run-off from roads, houses and commercial areas, run-off from farmland, and seepage into groundwater from developed landscapes of all kinds. Diffuse sources are often individually minor, but collectively significant.

It is irrelevant whether the source is a pipe or not, more important is that such contamination is driven by the nature of the land use and the impact of rainfall events.

In the Significant Water Management Issues report (2007), the importance of diffuse sources of pollution was very evident:

  • for rivers, diffuse sources associated with agriculture were the largest sector identified;

  • for rivers, diffuse sources accounted for three of the top four sectors (agriculture, collection and treatment of sewage, urban development (rainfall driven contaminated drainage), and forestry);

  • for lochs at risk of failing to meet good status, agriculture is again the largest sector by impact and forestry is a close third (behind aquaculture).

  • agriculture was also important in transitional and coastal waters, the second largest impact.

How is it regulated?

Diffuse pollution is regulated under the Water Environment (Controlled Activities) (Scotland) Regulations 2005 (CAR) which provide SEPA with powers to control activities such as abstractions, impoundments and engineering works.

If you have knowledge of case study sites or developments, or diffuse pollution hotspots, or are involved with projects and other work that can inform development of action programmes in Scotland, let us know by emailing diffuse.pollution@sepa.org.uk