In recent years, legislation and regulatory advice from the Environment Agency have been introduced to protect designated catchment areas across England from the impacts of increased nutrient run-off.

Given that watercourses create essential ecosystems – supporting aquatic organisms (fauna and flora), natural habitats and recreation for humans – there is a need to protect them from pollution. Various land uses (agriculture, wastewater treatment and housing developments) have the potential to contribute to nutrient pollution by releasing nitrogen and phosphates into watercourses.