Hand holding a test tube in water

Farmers must act if Poole Harbour is to be restored

Farms around the harbour must reduce the amount of harmful nitrates entering the water
03 March 2022 , By Steve Smethurst

The EA is providing farmers with tools to calculate nutrients being lost to the natural environment, and tasking them with reporting on their compliance and nutrient loss, in order to save harbour

Poole Harbour in Dorset is paying the price of 50 years’ worth of nutrients leaching into the waters from surrounding farms, prompting the Environment Agency (EA) to task farmers with halving the amount of pollutants pouring into the water. The amount of nitrogen – widely used in synthetic fertilisers – entering the harbour has more than doubled since the 1960s to around 2,300 tonnes/year.

Excessive nitrogen pollution is harmful to biodiversity as it allows nitrogen-tolerant species to thrive at the expense of other wild plants. One consequence is that the harbour’s mudflats have become covered in green algae, which has smothered sea grass and saltmarsh, to the detriment of wetland birds and other wildlife ecosystems.

As the harbour is designated a Special Protection Area (SPA), Site of Special Scientific Interest (SSSI) and Ramsar (international wetlands) site, this has proved concerning. 

The EA has set out interim nitrogen and phosphorus targets that states that nitrogen loads reaching the harbour should be reduced to 1,500 tonnes/year, and ortho-phosphate (OP) loads from 51 to 22 tonnes/year.

Farmers must now report on their compliance and nutrient loss. The EA is providing them with tools that allow them to calculate the amount of nutrients they are losing to the natural environment and to ensure they are compliant with existing regulations. The EA warns that ‘those farmers not returning information are likely to be prioritised for inspection by newly-appointed agricultural officers.’

Farmers are also being advised to avoid planting crops like maize on ‘high-risk’ land, specifically steep slopes with thin soil that is prone to run-off, and in some cases will have to cut their overall fertiliser use or risk a fine under the Environmental Permitting Regulations.

“It will take several years for this reduction to have an effect on levels of algae as it can take many years for the nutrients to drain into Poole Harbour from the surrounding land.”

Graham Farrant, Chief Executive at Bournemouth, Christchurch and Poole Council (BCP Council) said that BCP council welcomed the action by the Environment Agency, which will complement the council’s ‘Nitrogen Reduction in Poole Harbour Supplementary Planning Document - How residential and commercial development in the catchment of Poole Harbour will achieve nitrogen neutrality’.  

It is recognised that it will take several years for this reduction to have an effect on levels of algae as it can take many years for the nutrients to drain into Poole Harbour from the surrounding land,” said Farrant.

Alongside farmers, the EA is working with Wessex Water, local authorities and local industries. The EA Wessex Area is applying the same principles across its highest-risk groundwater zones, for example. Giles Bryan, Senior Technical Specialist for the Wessex Area, said it has been working closely with Natural England, the farming community and the water company to agree the new water quality objectives. 

“This plan will ensure all sectors that have contributed to rising nutrient concentrations will proportionally deliver the improvements and solutions this environment needs,” he said.

Nikki Hiorns, manager for Natural England, described the setting of tighter water quality targets as an important start to restoring water quality in the harbour. “Reducing the nutrients entering the catchment and restoring the harbour is achievable,” she said, “but only by continuing to work with farmers and other stakeholders.”

Image credit: Shutterstock

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