The Environment Agency has published a detailed new report on challenges created for the water environment by phosphorus, including sources of phosphorus, eutrophication issues, which examines current and future problems and solutions.

Phosphorus (P) and nitrogen (N) are the main nutrients involved in eutrophication, with phosphorus the main cause of eutrophication in freshwaters.

The Environment Agency and other interested groups have identified the risks and impacts of freshwater eutrophication in England as a significant concern for more than two decades.

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.

P concentrations in England’s rivers increased significantly between 1950 and the 1980s due to the introduction of P-based detergents, population growth and the growing use of artificial P fertilisers.

Despite good progress in tackling phosphorus pollution since 1990, 55% of assessed river water bodies and 75% of assessed lake water bodies in England fail the current Water Framework Directive Regulations phosphorus standards for good ecological status which aim to prevent eutrophication.

Phosphorus is the most common cause of water quality failures under the WFDR in England - the number one reason for water bodies not achieving good ecological status.

The main sources of phosphorus in rivers and lakes are sewage effluent (primarily from water industry sewage treatment works) and losses from agricultural land. Food waste, food and drink additives and P dosing of drinking waters all contribute to sewage P loadings. Septic tanks and package sewage treatment plants are small sources nationally but can be important locally, particularly in the headwaters of catchments. Leaking water mains are a newly identified P source entering ground and surface waters.

However, phosphorus loadings to English rivers from water industry sewage treatment works (STWs) have reduced dramatically since 1995. By 2020 the STW P load will have been cut by 66% (to 7.2kt/year), at a cost of £2.1 billion capital, with further reductions committed for the PR19 water industry investment period 2020 to 2025.

Agriculture and rural land management has now overtaken water industry STWs as the most common cause of water bodies not achieving good status for P.. This is a significant change from second cycle of the river basin management plans when water industry sewage works were the most common cause.

The report describes:

• current and potential future problems with high concentrations of phosphorus and eutrophication in freshwaters
• sources and evidence gaps
• current solutions
• the extent of the challenge for agricultural and non-agricultural sources
• potential future approaches and solutions
• A set of annexes include:
• current and possible future control measures for the main sources of phosphorus
• river basin management planning assumptions
• a summary of projects to close the evidence gap

Click here to download the report in full