Spring and the increase in agricultural water pollution from nutrient enrichment

Spring and the increase in agricultural water pollution from nutrient enrichment

Richard Garner Williams, National Officer for Wales
19 May 2021

For much of the natural environment spring is a season of productivity and new life. For rivers it highlights agricultural water pollution and the overwhelming amount of waste that intensive, modern farming produces from animal bi-products to arable run-off. 

Despite Farming Rules for Water, which came into effect in England in 2018, and new rules just being introduced for Wales the challenge, of farm inspections and enforcement of legislation, remains. Farmers are given little incentive to follow the rules with regulator budgets limiting the likelihood of a farm inspection to once every 260 years. Yet, according to evidence collected by the Environment Agency, the body responsible for inspecting and enforcing Farming Rules for Water, 40% of English rivers are failing to meet good ecological status because of agricultural water pollution.

Water Action - spreading slurry - 190521

Nutrient enrichment

One of the major problems from agricultural water pollution is nutrients in the form of slurry and fertilisers. Excess nutrients, specifically phosphorous and nitrogen, end up in our rivers, starving them of oxygen and killing the wild fish populations they support. Lesley Griffiths, the current Welsh Minister for Rural Affairs, stated:

The impacts of intensive agriculture on rivers and fish are largely as a consequence of the impacts of nutrients on the natural balance of aquatic plants and algae. A rise in the availability of nutrients, especially phosphorous, leads to a rapid increase in algal growth which depletes the surrounding water of its oxygen content. Pollutants make varying demands on the available oxygen according to type”.

You can find more information about the impacts of agricultural water pollution, specifically excess nutrients on waterbodies, in our report on the impacts of elevated phosphorous on flora and fauna in river systems.

Getty Images: algal bloom in freshwater.
Getty Images: algal bloom in freshwater.

Where does nutrient pollution come from?


Filters into watercourses as ground pollution in the form off:

  • Slurry, a liquid combination of faeces and urine, from housed cattle – mostly dairy but some beef. Problems arise from excessive spreading.
  • Poultry litter from bird houses. Theoretically more easily managed than slurry as it is relatively dry and can be contained and moved with much greater ease. Run off from free range units, however, poses a great threat to watercourses.
  • Pig slurry from housed herds and run off and permeation to groundwater from outdoor units.


These manifest in two ways:

  • Excessive application or applying in unfavourable weather conditions (i.e., rain), accidental spills or infrastructure failures.
  • Excessive dispersal (spreading) over time resulting in a build-up of nutrients in the land which then leaches into watercourses.
Farmyard run-off.
Farmyard run-off.

Farming and the environment balance a delicate set of scales that desperately need more equilibrium. If stronger Government enforcement is not achieved agricultural water pollution will continue to kill wild fish and destroy the freshwater environment. The damage is reversible but the time to act is now.

How can you help?

If you see something you don’t like take a photograph, make a note of the location, time and date and report your concerns using the form on our website. We will follow up with the Environment Agency.