Diffuse pollution resulting from agricultural practices, typically arises when nutrients, pesticides, herbicides and fine sediments enter watercourses from the land, either by run-off (i.e. surface water) or leaching (i.e. water moving through soil into groundwater).  This can happen when dung or chemicals are spread in close proximity to watercourses; when livestock poach riverbanks; and when the land is cultivated too close to the watercourse.  When these activities take place across the catchment during heavy or prolonged rainfall, water quality, riparian habitats and the species that depend on them, are negatively impacted.  

The Nitrates Directive, which was introduced in 1991, aims to protect water quality and requires action to be taken to reduce the risk in identified areas where Nitrate limits have been, or are likely to be, exceeded. These identified areas are known as 'Nitrate Vulnerable Zones' (NVZ). There are five designated NVZs in Scotland and the South Esk catchment is part of one of them - a map of the Strathmore, Fife and Angus NVZ can be found here. 

The risk of diffuse pollution from agriculture can be reduced by:

• Adopting regenerative agriculture practices such as growing cover crops over winter, minimising soil cultivation and loosening compacted soil;
• Having a holistic nutrient management plan, based on soil sampling results;
• Increasing the crop rotation;
• Cultivating along the contour, where appropriate;
• Introducing or increasing the width of natural barriers such as riparian buffer strips, field margins and wetlands;
• Changing the land use in high-risk areas, for example, having permanent grassland and woodland in flood-prone areas; and
• Providing water troughs for livestock and exclude them from water courses.

Further information on the occurrence of chemicals associated with agriculture and other industries, and their impact on individual water courses in the catchment can be found at in SEPA’s Water Classification Hub.