Agricultural pollution

Fertilisers, pesticides, and manure are a key part of food production, but their overuse and mismanagement results in these chemicals entering our rivers. Primarily, chemical pollution occurs through the process of surface run-off during excess rainfall, where pollutant-rich soils wash into rivers and waterways, introducing excessive nutrients that disrupt river ecosystems.

70% of nitrogen and 25% of phosphorus in UK waters can be attributed to attributed to agricultural runoff.

The intensification of farming, especially in the dairy sector, has led to a surge in manure and slurry production meaning a greater need for high-quality storage units. However, slurry storage units are costly to install and maintain, making them unaffordable for many farmers. As a result, many slurry storage units are faulty, and leach high-nutrient slurry and manure onto the land and into our waterways. In other cases, farmers opt for cheaper, environmentally harmful alternatives like spreading slurry on fields, entering our rivers through surface run-off. Read our Dairy Report for more information.

Damaged soils and weakened riverbanks are more vulnerable as climate change causes more intense and frequent rainfall, accelerating soil erosion and sediment runoff, which impacts water quality and soil stability. Additionally, increasingly frequent hot, dry periods bake the soil, preventing rain from being absorbed.

Policy and regulatory failures have exacerbated this issue, with insufficient support for farmers to improve environmental performance and inadequate enforcement of laws to prevent river degradation.

The current policy framework for regulating the relevant agricultural practices is outlined in the Farming Rules for Water (2018). These rules seek to prevent agricultural pollution of rivers, by regulating fertiliser and pesticide use, livestock management, and slurry storage.

Yet, these rules fall short in their protection for rivers and are poorly enforced. Analysis revealed that farmers can expect to receive an inspection from the regulator just once every 263 years, and despite the recruitment in 2022 of 50 new agriculture regulatory inspection officers, the regularity of inspections increases to only once every 50 years.

Even then, the government’s approach is often to ‘advise’ rather than enforce the law.

A broader issue lies in the supply chain, which demands cheap produce from farmers but fails to pay for the true cost of production, particularly its environmental impact. As a result, the public shoulders the burden—both through environmental damage and the taxpayer-funded costs of the ELMS. Both consumers and the supermarkets must take more financial and environmental responsibility for the pollution caused by agricultural practices.

High quantities of phosphates and nitrates in surface run-off disturb the ecological balance of the river, instigating the process of eutrophication. Eutrophication occurs when excessive nutrients enter a waterway, stimulating algae growth. These spurts of algae growth are known as ‘algal blooms’. The algae growth blocks sunlight from entering the water, disrupting the process of photosynthesis and starving the river of oxygen. This creates ecological ‘dead zones’ in the river, destroying habitats for important invertebrates and fish larvae. River Action’s campaign on the River Wye highlighted the severe impacts of nutrient run off, emphasising the need for stricter regulation.

Pictured: Algal Bloom, Lough Neagh, Northern Ireland.

Arable farmland across England and Wales shows significant signs of erosion, with already damaged soils more likely to be swept away. This soil ends up in our rivers as sediment, reducing water quality and damaging habitats by coating riverbeds in a layer of silt and suffocating life beneath. Erosion also reduces soil health, making farming more challenging and often leading to the increased use of fertilisers, resulting in a cycle of environmental degradation and harmful run-off into our rivers.

Additionally, the longer, drier summers as a result of climate change harden soils, reducing their ability to absorb rain. This leads to more frequent flash flooding events, which can have catastrophic consequences, washing away surface soil and nutrient-rich fertilisers into our rivers.

Improper slurry management and nutrient runoff drive up water treatment costs for water companies tasked with removing these excess nutrients, bacteria, and sediment. The financial burden of these enhanced treatment processes often falls on consumers. Water companies may pass increased operational costs onto households through higher water bills. A study by the Parliamentary Office of Science and Technology (POST) highlights that preventing water pollution at source can have a cost-benefit ratio as high as 1:65, underscoring the economic advantages of proactive measures.

Agricultural pollution often remains unchecked and unaddressed due to weak regulatory enforcement and inadequate penalties. We need a system that issues penalties to the farms that pollute our rivers, whilst also providing support and expert guidance.

This means properly enforcing existing rules such as the Farming Rules for Water and slurry regulations and properly resourcing the Environment Agency to train staff and carry out regular inspections. High-risk sectors, including intensive livestock and large dairy and beef operations, must be subject to appropriate permitting and oversight, and serious or repeat breaches must face meaningful consequences.

To protect and restore our rivers farmers need clearer rules, practical guidance, and the financial support to comply. Many farmers are constrained by under-investment, complex planning systems and agricultural subsidy schemes, such as the Environmental Land Management Schemes (ELMS), that are difficult to access.

Support should focus on making it easier for farmers to upgrade failing infrastructure, meet regulatory requirements, and manage nutrients responsibly. Supermarkets and food companies should also offer fair pricing that enables farmers to invest in sustainable practices.

Many of the most effective measures for reducing agricultural pollution are about how land is managed, because runoff and erosion are the main routes by which nutrients, sediment and chemicals reach rivers. Preventing pollution through water-sensitive land management is often cheaper and more durable than relying on downstream treatment once contaminants are already in the water.

This includes practical changes such as improving soil structure and ground cover, integrated pest management, and rotational grazing. River buffers – where agriculture ends and natural vegetation begins – are another proven measure: woodland, scrub and grass margins can trap sediment and nutrients before they enter watercourses, reduce bank erosion, and provide habitat.

These measures work best when they are planned at the scale of the catchment. Nutrients and sediment do not stay within field boundaries, and in some areas long-term “legacy” nutrients stored in soils continue to drive pollution even after practices improve. Catchment-level coordination and robust whole-farm nutrient planning help ensure nutrients are applied in line with soil and crop need, avoid oversaturation in stressed areas, and address cumulative impacts in rivers that are already failing ecological standards.

See this detailed proposal The Beaver Trust submitted to the government here.