Phosphates and nitrates are all around us – naturally occurring and man-made. They are essential to plant and animal life and our planet would be a very barren and unwelcoming place without them.
But these life-giving chemicals can also be destructive when they reach our rivers and wetlands, with local authorities required to participate in the safeguarding of protected habitats which are adversely affected by high phosphate or nitrate levels and ensure that new developments within catchment areas of protected wetland habitats/waterbodies do not increase the phosphate or nitrate levels.
This has wide-reaching implications for developers operating within affected areas and further areas may be affected as other habitats in need of protection from high phosphate or nitrate levels are identified.
What’s the problem with nitrates and phosphates?
Nitrates and phosphates are naturally occurring and also widely found in a host of products including artificial fertilisers, cattle feed and detergents. They are incredibly useful – until they reach bodies of water.
The problem is that as well as giving us healthy crops and bright white shirts, when the chemicals find their way into watercourses and wetlands in high concentration, they encourage growth of aquatic algae and plants. This dramatic increase can in turn negatively impact other organisms within the habitat by preventing their access to light and water. Over time this depletes the resilience of the habitat and can have disastrous effects on biodiversity and the food chain.
The UK is fortunate to be home to a number of internationally and nationally important wetlands and waters, including the Solent, the Somerset Levels and moors and the River Lugg in Herefordshire. Those habitats, however, are delicate and the very reasons for their international and national recognition (i.e. their biodiversity and strategic locations) make them particularly vulnerable to nitrate and phosphate damage.
By building houses or carrying out other development in the catchment areas of vulnerable (and usually protected) wetland habitats, the concentration of nitrates and phosphates in the local water is almost inevitably going to rise. This is because the amount of phosphate/nitrate generated by household activities will usually outstrip the ability of the local water treatment works to remove it from processed sewage water ultimately discharged into local watercourses.
As a result, there is a greater requirement on local planning authorities to scrutinise the effects of granting planning permission for further development where water quality within protected wetland environments is already unfavourable or at risk of becoming unfavourable.
What are the rules now?
Natural England, the body that advises the government on the natural environment, is the lead on producing guidance for local authorities - similarly, it is also leading on the rollout of Biodiversity Net Gain (BNG) measures.
Natural England advises that the impact of contaminants to a protected site should be assessed at the planning application stage and that local planning authorities should only grant permission for developments where “nutrient neutrality” can be achieved.
How can nutrient neutrality be achieved?
The most effective way to eliminate contamination is for nitrates and phosphates to never leave the site of development. In some cases, this can be achieved with treatment works on-site that neutralise phosphates and nitrates or dispose of them safely then discharging wastewater to the sewage system to be further treated by water authorities.
In practice, this is difficult to achieve by on-site measures alone, and most developments are likely to be a source of phosphates that will find their way to watercourses until all water recycling centres are upgraded. As a result, there are currently two other options available:
Offsetting - The developer secures land that currently emits phosphates and nitrates (for example, farmland) and commits to rewilding it, effectively balancing out the contamination caused by the development. That offsetting can be achieved onsite by sterilising part of the potential development area, or by creating an offsite scheme.
Purchasing credits - This is similar to the system of BNG credits, in that the developer buys credits which fund mitigation schemes in the catchment area where the development is taking place - i.e. wetland and woodland creation, to soak up or mitigate the impacts of unavoidable nutrient pollution.
What does this mean for developers?
Developers in areas where there is a protected site within the same catchment area will need to be aware of their obligations relating to nitrates and phosphates and take advice at an early stage from a specialist.
It will be essential for them to carry out a Habitats Regulation Assessment using a recognised phosphate calculation tool to satisfy the requirements set out by Natural England to ensure developments do not contribute to increased nutrient levels.
Local authorities will vary in how they seek to ensure conditions are met – this may be, for example, through Section 106 planning obligations agreements or possibly through Council-led projects. We are still feeling our way – with national and regional policies slowly being developed and rolled out. Developers, however, should be aware of the extra time and costs the nutrients issues are likely to bring into the planning process, as well as the need for sound, specialist advice from the planning stages right through the life cycle of a scheme.
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