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Steve Mustow, Environmental Consulting & Consenting Director (Water), StantecIt’s going to be a fine-line balancing act between building enough homes, while protecting threatened species and water quality.
In the most sensitive catchment areas in England, Nutrient Management Plans (NMPs) have been put in place. Why? To help protect key protected habitats sites including Special Protection Areas (SPAs), Special Areas of Conservation (SACs) and sites designated under the Ramsar Convention. These habitats sites provide a network of core breeding and resting grounds to safeguard rare and threatened species.
What are the implications of these NMPs and the restrictions being placed on development to prevent increased nutrient pollution? How will this affect the growth objectives of the UK as it tries to solve a housing crisis?
It’s not going to be easy. We must address the balancing act between building enough homes for a growing population, while protecting our ever-threatened environment.
Areas under the spotlight
Stretches of several of our rivers are within SACs and have had NMPs put in place. For example, on the River Avon, phosphorus is preventing favourable conservation status being achieved across the catchment. On the River Wye, the levels of phosphate exceed the target level in the conservation objectives, and on the River Clun—a SAC for freshwater pearl mussel—the freshwater pearl mussel population has been non-functioning since 1995 because of phosphorus, nitrogen, and sediment pollution. On the River Mease, excessive levels of phosphate are preventing the achievement of favourable condition. And at the Poole Harbour SPA, increasing nitrogen levels from sewage and agriculture are contributing to the growth of algal mats in the harbour, restricting food for wading birds and smothering estuarine habitats.
Controlling the pollution
NMPs provide solutions to address excessive phosphorus and nitrogen, through a combined approach to tackle both point sources and diffuse sources.
For point sources, actions may include upgrading sewage treatment works to strip out nutrients; reducing phosphorus emissions from fish farms and cress farms; preventing infiltration to the sewer network; reducing discharges from Combined Sewer Overflows and retrofitting Sustainable Urban Drainage Systems.
“Careful attention to providing sufficient evidence showing that nutrient neutrality or betterment will be achieved is now the norm”
For diffuse sources, various measures can be applied. Integrated soil, water, and nutrient management plans for farms; encouraging the use of winter storage reservoirs within the horticultural sector; rectifying sewer misconnections and reverting to semi natural vegetation are just a few.
Implications for new developments
New housing developments, and similar developments such as hotels and student accommodation increase nutrient loads in sewage. There is an urgent requirement for new housing in the UK, but there is also an urgency to protect our environment and waters. We need to strike a balance between environmental protection and the implications of construction.
Developments may still be able to proceed, where they can prove that resulting nutrients can be removed at the sewage treatment works or via offsetting and other measures. And not all restrictions are the same for each catchment. In the catchment of the River Mease, new development must contribute to the Developer Contribution Scheme (DCS) to be phosphate neutral. The contribution is assessed on the development size and its sustainability. However, the DCS has recently been used up, so the relevant councils are leading work with the Rivers Trust to try and identify and cost appropriate phosphorous mitigation measures, potentially in the form of a new DCS. At Poole Harbour, new development must mitigate 25 percent of the additional nitrogen it produces—the other 75 percent is expected to be removed at the sewage treatment works by Wessex Water.
However, in several catchments, house building has effectively been put on hold due to strict requirements from Natural England for developments to meet nutrient betterment or neutrality. For example, in Herefordshire the Council wrote to the Secretary of State for Environment, Food and Rural Affairs in June 2021, stating that approximately 1650 houses were caught up in applications until a way forward on nutrient pollution could be found. This applied to both commercial and agricultural development, as well as proposals for the development of NHS facilities.
Seeking solutions
There is continuing concern amongst councils, planning authorities, and developers about how to meet the strict interpretation of nutrient neutrality requirements by Natural England. These requirements were born out of the outcome of a law judgement known as the ‘Dutch judgement’.
Councils have therefore been refining their nutrient management plans and strategies so that they are based on comprehensive and up-to-date information. Careful attention to providing sufficient evidence showing that nutrient neutrality or betterment will be achieved is now the norm. As a bonus linked to that, several councils have been developing nutrient budget calculators, such as the phosphate budget calculator developed by the Somerset councils.
These solutions may allow housing development to recommence. However, there is concern whether the solutions being developed by councils are sufficiently well advanced, and feasible. There are still considerable practical difficulties to overcome, including availability of suitable land for offsetting schemes such as wetlands and issues of financial viability.
The government response to this problem has been slow, despite the significant impact on economic development. However, in 2022 there have been some significant steps forward. These include the publication of comprehensive guidance for planning authorities in March and the announcement in July of plans for Natural England to accredit mitigation delivered through a new Nutrient Mitigation Scheme. An amendment to the Levelling Up and Regeneration Bill will also be tabled to place a new statutory duty on water and sewerage companies in England to upgrade wastewater treatment works to the highest technically achievable limits by 2030 in nutrient neutrality areas.
These developments are welcome, although given the complexity of the new guidance from Natural England there may be a lag before it is fully implemented by planning authorities. It is important that the Nutrient Mitigation Scheme is put in place as soon as possible, but it must avoid adversely impacting existing schemes. Rapid action will also be required to ensure that improvements to wastewater treatment works are incorporated into company investment plans if delivery is to be achieved by 2030.
