C1. Thames Basin Heaths SPA SPD

The Thames Basin Heaths SPA is an internationally significant network of lowland heathland habitats, designated to protect rare ground-nesting birds such as Woodlark, Nightjar, and Dartford warbler. 

Within Bracknell Forest, the SPA includes Broadmoor to Bagshot Heaths SSSI, Sandhurst to Owlsmoor Bogs SSSI and Heaths / Wildmoor Heath SSSI. A significant part of the borough falls within five kilometres of the SPA, with some areas lying within 400 metres, meaning that many residential developments could potentially impact the SPA if mitigation is not implemented.

The Thames Basin Heaths SPA Supplementary Planning Document supplements policies set out in the Bracknell Forest Local Plan, LP31 and LP32, that provide the statutory framework for protecting the SPA. The SPD provides more detailed guidance to ensure compliance with the Habitats Regulations and sets out in practical terms how avoidance and mitigation requirements should be applied, ensuring that mitigation measures are consistently applied across the council area.

The Thames Basin Heaths SPA Supplementary Planning Document (SPD) details guidance for developers, decision-makers, and stakeholders. It replaces the previous 2018 SPD and is a material consideration in planning applications.

At a strategic level, it sets out a borough-wide framework for understanding the Zones of Influence (ZoI) and the types of mitigation required for all new residential development. At the site-specific level, it provides tailored guidance for developments depending on their proximity to the SPA, taking into account the sensitivity of nearby habitats, the presence of SSSIs, and potential pathways of impact, such as increased recreational pressure on heathland.

To achieve this, the SPD gives a structured mitigation framework that converts high-level strategic policy requirements into measurable and enforceable development requirements. Central to this is a spatially tiered approach that links development impacts directly to defined ZoI around the SPA. These zones provide a clear decision-making hierarchy:

• 0m to 400m zone: There is a presumption against net new residential development because mitigation is generally considered insufficient to avoid adverse effects. Any proposal must demonstrate through Habitats Regulations Assessment that no adverse effect will occur. Some sites close to the SPA may require provision exceeding this baseline where impacts are likely to be greater.
• 400m to 5km zone: Development is likely to have significant effects unless mitigation is provided, and avoidance measures must be delivered before occupation and secured in perpetuity. Suitable Alternative Natural Green Space (SANG) provision must meet a minimum standard of 8 ha per 1,000 residents (equivalent to roughly 1 ha per 125 residents) and contributions must be made to Strategic Access Management and Monitoring (SAMM) measures.
• 5km to 7km zone: Large schemes (typically ≥50 units) require individual assessment with Natural England to determine whether mitigation is necessary. Mitigation land requirements for alternative recreation greenspace provision may be reduced to around 2 ha per 1,000 residents, subject to case-specific assessment.

• Evidence led 

The SPD is underpinned by a robust and comprehensive evidence base. The ZoI and mitigation standards are derived from visitor survey data, ecological research, and long-term monitoring across the Thames Basin Heaths Partnership area. This evidence-led approach ensures that mitigation measures are proportionate, justified, and directly related to identified impact pathways, rather than being purely precautionary or arbitrary. The strong evidence base also improves the legal robustness and soundness of the approach under the Habitats Regulations.

• Clear messaging 

A key strength of the SPD is the clarity and structure of the guidance. The document uses structured explanations, tables, flow diagrams, and clearly organised sections so that users can quickly determine whether development is likely to trigger mitigation and what form that mitigation should take. This structured presentation supports consistent decision-making, reduces uncertainty, and enables developers to anticipate mitigation requirements early in the scheme design process.

• Use of spatial zones 

Spatial ZoI are clearly defined and directly linked to specific mitigation requirements, reducing ambiguity and limiting the need for case-by-case interpretation. The use of mapped zones provides clarity for applicants, planning officers, and decision-makers, and ensures a consistent approach to mitigation across the plan area. This spatial approach also reflects visitor behaviour evidence and therefore aligns mitigation requirements with actual recreational pressure patterns.

• Detailed information on delivery 

The SPD provides detailed guidance to applicants and developers to support the delivery of mitigation. This includes information on financial contributions, SANG standards and long-term maintenance arrangements.

Financial contributions toward strategic mitigation are standardised through tariff schedules and index-linked rates, ensuring that requirements can be calculated transparently and remain effective over time. These quantified mechanisms increase transparency and defensibility in planning decisions while allowing ecological protection measures to scale alongside development.

Mitigation measures must be secured through enforceable mechanisms such as planning conditions and Section 106 obligations, with clear requirements regarding the timing and delivery of mitigation before development impacts occur. This ensures mitigation is deliverable and legally secured.

• Partnership working 

The SPD is embedded within a broader strategic mitigation framework operating across multiple local authorities through the Thames Basin Heaths Joint Strategic Partnership Board and Delivery Framework. This ensures that mitigation is coordinated at an ecologically meaningful scale rather than fragmented across administrative boundaries. Strategic partnership working is particularly important for protected sites where impacts arise from cumulative development across a wide area.

• Monitoring 

The SPD incorporates monitoring and review mechanisms, allowing mitigation effectiveness to be tested and refined over time. As the document represents a later iteration of the strategy, it demonstrates how policy can evolve through ongoing evidence gathering and adaptive management. This monitoring-led approach ensures that mitigation remains effective and allows the strategy to respond to changes in visitor behaviour, housing growth, and environmental conditions over time.