Diffuse water pollution can arise from many sources, which may be small individually, but their collective impact can be damaging. Diffuse pollution can be caused by current and past land use in agricultural and urban environments.
Diffuse water pollution
Diffuse water pollution is mainly related to the way we use and manage land and soil. It can affect rivers, lakes, coastal waters and groundwaters.
Groundwaters are vulnerable from, and can be affected by, pollutants that leach from the land surface and from areas of contaminated land. Surface waters are affected by rainfall that washes over and off the land (run-off).
Rivers can also be influenced by springs and seepages from groundwater that contribute to their flow . If the groundwater connection with surface waters is high, pollution can pass from one to affect the other.
Run-off has increased as agriculture has intensified and as we have built more roads and houses. This often happens where we have degraded the natural permeability of the landscape and reduced its capacity to retain water.
Unlike point source pollution, we cannot easily control diffuse pollution by issuing licences or permits. Regulatory approaches have to be more subtle and in many cases need to be well connected to the land use planning system.
Diffuse pollution tends to arise from sites not directly regulated by the Environment Agency. However, we are continuing to make water quality improvements by tackling diffuse pollution issues and as we adopt innovative ways of controlling the risks from diffuse sources. The Water Framework Directive will offer fresh opportunities for us to tackle these risks.