Water pollution from animal ag

Good reading you haven't done: page 32 onwards of this parliamenary committee report.

Fertilizers used in agriculture, particularly those containing nitrates and phosphates, are a major source of nutrient pollution. When it rains, excess nutrients from fertilizers can be washed off fields and into nearby rivers and streams. This runoff leads to an overabundance of nutrients in water bodies, causing eutrophication, which can result in harmful algal blooms and dead zones where oxygen levels are too low to support aquatic life.

Manure from livestock contains not only nutrients like nitrogen and phosphorus but also pathogens, organic matter, and sometimes antibiotics.

Nitrogen (N) and Phosphorus (P) cause Eutrophication. It is estimated that agriculture accounts for around 61% of the total nitrogen and 28% of phosphorus load in river water in England and Wales .

Nitrogen

N is the main cause of eutrophication in Saltwater
In nitrogen-contaminated water, algae can multiply faster than usual, blocking sunlight for plants lower down. When this algae dies off and decomposes, the process consumes oxygen in the water, suffocating aquatic life.

Phosphorus (P)

In the body of a chicken, phosphorus is converted to phosphate and excreted in manure, which is subsequently applied to the land as a fertiliser.
P is the main cause of eutrophication in freshwater
P accounts for more water bodies failing to achieve good ecological status than any other water quality pressure.

Really good review of industrial ag and water pollution: https://foodprint.org/issues/how-industrial-agriculture-affects-our-water/

just 14% of English rivers are of good ecological standard Figures released by the Environment Agency show for the first time that no river has achieved good chemical status, suggesting pollution from sewage discharge, chemicals and agriculture are having a huge impact on river quality. In 2016, 97% of rivers were judged to have good chemical status, though the standard of tests used this time was tougher.

How it happens

Can either be from a discrete point, such as a leaking slurry store, or diffuse, caused by an action spread across a large area.
It usually happens when they are applied in excess or during wet weather.
The Green Alliance outlines ten recommendations, from quick wins to longer term action, to tackle pollution from agriculture.
Policy idea: More of the budget should be directed into the Higher Tier and Landscape Recovery Schemes which can support smaller marginal and upland farms in water catchments. Continuing the Slurry Infrastructure Grant, and allowing small farms to access larger grants, will improve slurry management and prevent runoff into water courses.

Monitoring and regulations are insufficient

In the UK, 2/3 of rivers are not sampled enough by the EA, and 43% had no samples taken in 2023. Evidence from published studies have shown that spot sampling can underestimate phosphorous pollution loads by 60% and that up to 80% of the phosphorous pollution load can enter rivers in just 2 or 3 rainfall runoff events.

slurry storage regulations aren’t working. In a study in Devon, 90% of farms visited by an Environment Agency officer were violating slurry storage regulations. Of these, two thirds created river pollution.

Why care about polluted water?

Eutrophication increases the cost of drinking water abstraction and treatment, adversely affects angling, water sports and other recreational activities, and causes the loss of sensitive plants and animals in rivers and lakes.