Diffuse pollution refers to input occurring over a wide area, rather than via one defined point
Pollution running off farmland and tracks, and from sewers and septic tanks in rural areas adds to the nutrient and sediment loads in the catchment. Increased nutrient levels lead to increased algal growth, which smothers the river bed and the plants growing on it. Pesticides, including the slug pellet Metaldehyde, also cause problems in the catchment particularly on the River Enbourne. Sediment washed off fields and farm tracks chokes the clean gravels of the river bed, making them unsuitable for fish to spawn.
Catchment senstitive farming is an important tool for helping farmers and land managers to reduce their impact on the river. Catchment Sensitive Farming has been active in the catchment for several years.