Human activity can create an imbalance of nutrients, including nitrogen and phosphorus, in river courses; sources of additional nutrients include agricultural fertiliser run off, animal waste, and wastewater from homes. A major consequence of excessive phosphate levels is eutrophication: seasonal algae bloom, which can restrict the growth, distribution and variety of food for native bird species and marine life.
Self-builders in Herefordshire are facing planning delays and obstacles as a result of a housing moratorium issued by the local council. Herefordshire Council issued the suspension on new development due to phosphate contamination in the protected River Lugg catchment area - which covers about 40% of the county - in October 2019. The catchment forms part of the River Wye Special Area of Conservation (SAC), and currently exceeds its limits for phosphates, as a result of water pollution.