Understanding the Shadow Habitats Regulations Assessment (SHRA) for Salisbury Developments

When planning a residential conversion in an urban center like Salisbury, developers must navigate a complex landscape of environmental law. A critical component of this process is the Shadow Habitats Regulations Assessment (SHRA).

Recently, a project involving the conversion of commercial space into 44 apartments in the heart of the city underwent this rigorous evaluation to ensure the protection of the River Avon Special Area for Conservation (SAC).

What is a Shadow Habitats Regulations Assessment (SHRA)?

An SHRA is a technical report prepared by environmental consultants to assist the Competent Authority (in this case, Wiltshire Council) in fulfilling their legal obligations under the Habitats Regulations 2017.

Because the River Avon is highly sensitive to nutrient loading, any project that increases wastewater must prove it will not adversely affect the “integrity” of the protected site.

Atlantic Salmon

The Nutrient Neutrality Challenge in Wiltshire

The primary hurdle for Salisbury developments is Phosphorus (TP). Excessive phosphorus leads to eutrophication—a process that depletes oxygen in the water and threatens qualifying species such as:

• Atlantic Salmon (Salmo salar)

• Bullhead (Cottus gobio)

• Desmoulin’s Whorl Snail

For this specific city-center conversion, the initial Phosphorus Budget identified a potential loading of 4.03kg/year (including a 20% precautionary buffer).

Achieving Stage 2: Appropriate Assessment

Under Stage 1 (Screening), it was determined that a “Likely Significant Effect” could not be ruled out due to the site’s hydrological connectivity to the River Avon. This triggered a Stage 2: Appropriate Assessment.

To mitigate the impact, the project adopted two key strategies:

1. Water Efficiency: Restricting consumption to 85 litres per person/day to minimize wastewater volume.

2. Phosphorus Credits: The remaining 3.2kg/year budget is offset via a credit scheme managed by Wiltshire Council.

Key Takeaways for Developers

• Nutrient Neutrality is Mandatory: If your project is within the River Avon catchment, you must demonstrate a net-zero nutrient impact.

• The Role of Mitigation: Following the People Over Wind case law, mitigation (like purchasing credits) cannot be considered at the Screening stage; it must be addressed within the Appropriate Assessment.

• Strategic Planning: Securing phosphorus credits as a pre-commencement condition is often the only viable path for high-density urban conversions in Salisbury.

By utilizing a professional Shadow Habitats Regulations Assessment, developers can provide the necessary scientific evidence to Natural England and the local planning authority, ensuring that city growth and river conservation go hand-in-hand.