SEPA vs Environment Agency: Key Differences for Developers

Developers working across the UK border — or expanding from England into Scotland for the first time — quickly discover that the flood risk regulatory landscape is fundamentally different north of the border. While the underlying physical principles of flood risk are the same, the policy framework, the role of the regulator, the planning system, and the technical requirements diverge in ways that can catch the unwary off guard.

This article sets out the key differences between SEPA (the Scottish Environment Protection Agency) and the Environment Agency (EA) as they relate to development and flood risk, and provides practical guidance for developers and consultants navigating both systems.

The Regulatory Framework

England: NPPF and PPG

In England, flood risk policy for development is set by the National Planning Policy Framework (NPPF) and the associated Planning Practice Guidance (PPG). The NPPF establishes the Sequential Test and Exception Test, defines vulnerability categories, and sets out the expectations for Flood Risk Assessments.

The Environment Agency is a statutory consultee on planning applications in flood-risk areas and provides detailed technical guidance through its Standing Advice and bespoke consultation responses.

Scotland: NPF4 and SEPA Guidance

In Scotland, flood risk policy is set by National Planning Framework 4 (NPF4), which replaced the previous Scottish Planning Policy (SPP) in February 2023. NPF4 Policy 22 addresses flood risk and water management.

SEPA is a statutory consultee on planning applications that may be affected by flood risk. SEPA publishes its own guidance, including the “Land Use Vulnerability Guidance” and the “Technical Flood Risk Guidance for Stakeholders,” which set out how flood risk should be assessed and managed in the planning process.

Key Policy Differences

No Sequential Test in Scotland. One of the most significant differences is that Scotland does not have a Sequential Test in the same form as England. NPF4 Policy 22 adopts a risk-based approach: development must not be at significant risk of flooding, and must not materially increase flood risk elsewhere. But the English-style sequential process — requiring the developer to demonstrate that no sites at lower flood risk are available — does not apply.

No Exception Test in Scotland. Similarly, Scotland does not have an Exception Test. Instead, NPF4 sets out the types of development that are (and are not) appropriate in different flood risk categories. If the policy says the development is not appropriate, there is no formal mechanism to demonstrate that the wider benefits outweigh the risk.

Different vulnerability categories. Scotland uses its own vulnerability classification, set out in SEPA’s Land Use Vulnerability Guidance. The categories are broadly similar to England’s but differ in detail. For example, Scotland distinguishes between “most vulnerable” and “highly vulnerable” uses, and the compatibility with flood risk categories is different.

Functional floodplain. In England, Flood Zone 3b (the functional floodplain) is defined as land that would flood in a 1 in 20 year event. In Scotland, the equivalent concept is the “medium likelihood” flood extent (0.5% or 1 in 200 year event for coastal or 0.5% for river), which is a higher standard. SEPA defines its own risk categories: high likelihood (10% annual probability), medium likelihood (0.5% annual probability), and low likelihood (0.1% annual probability).

Flood Mapping

Environment Agency Flood Maps

The EA publishes three main flood mapping datasets:

Flood Map for Planning (Rivers and Sea). Shows Flood Zones 1, 2, 3a, and 3b. This is the primary dataset used for the Sequential Test and to determine when an FRA is required.

Risk of Flooding from Surface Water. Shows areas at risk of surface water flooding at three probability levels (high, medium, low).

Risk of Flooding from Reservoirs. Shows the maximum extent of flooding in the event of a reservoir breach.

The EA’s flood maps are based on national-scale hydrological and hydraulic modelling, supplemented by detailed local modelling in some areas.

SEPA Flood Maps

SEPA publishes flood maps that cover three sources:

River (fluvial) flooding. Shows the indicative extent of flooding at high likelihood (10% annual probability), medium likelihood (0.5%), and low likelihood (0.1%).

Coastal flooding. Shows the indicative extent of coastal flooding at the same three probability levels.

Surface water flooding. Shows areas at risk of surface water flooding. SEPA updated its surface water flood maps in 2025, providing significantly improved resolution and accuracy.

Key differences in mapping:

• SEPA’s maps use different probability thresholds than the EA’s. The EA’s “high risk” is 1% (1 in 100) for rivers; SEPA’s “medium likelihood” is 0.5% (1 in 200) for rivers, which is a more stringent threshold.
• SEPA’s maps are described as “indicative” and are not intended to replace site-specific flood risk assessment. The EA’s Flood Map for Planning is also indicative but is used more prescriptively in the planning process.
• SEPA’s maps do not distinguish between defended and undefended areas in the same way as the EA’s Flood Zones.

The Consultation Process

Environment Agency Consultation

In England, the EA is a statutory consultee on planning applications where the site is in Flood Zone 2 or 3, or where the development is “major” and in Flood Zone 1 with known surface water flood risk.

The EA’s consultation response can be:

• No objection — the FRA is satisfactory and the development is safe
• No objection subject to conditions — the EA recommends planning conditions to ensure flood risk is managed
• Objection — the FRA is inadequate, the development is unsafe, or the Sequential/Exception Test has not been passed

The EA publishes Standing Advice for minor development in flood zones, which the LPA uses to assess applications without bespoke EA consultation.

SEPA Consultation

In Scotland, SEPA is a statutory consultee on planning applications that may be at risk of flooding. SEPA’s consultation triggers are broadly similar to the EA’s but use the Scottish flood risk categories.

SEPA’s consultation response can be:

• No objection — the FRA is satisfactory
• No objection subject to conditions — SEPA recommends conditions
• Objection — the development is at unacceptable risk of flooding, or the FRA is inadequate
• Holding objection — SEPA requires further information before it can provide a substantive response

Key differences in consultation:

SEPA’s approach to objections is more binary. Where the EA might offer conditions that allow a development to proceed with modifications, SEPA is more likely to object outright if the flood risk is unacceptable. SEPA’s published guidance states that it will object to development in the medium likelihood flood extent (1 in 200 year) unless the development is appropriate for that level of risk.

SEPA does not provide a Standing Advice equivalent. While SEPA publishes general guidance, it does not have the same tiered consultation system as the EA. All applications where SEPA is consulted receive a bespoke response, which can lead to longer consultation timescales.

SEPA’s approach to climate change. SEPA requires climate change to be considered in all flood risk assessments, but does not publish the same granular, location-specific climate change allowances as the EA. Instead, SEPA’s guidance refers to the UKCP18 projections and provides general recommendations. The EA publishes specific percentage allowances for peak river flow and peak rainfall intensity by river basin district and time horizon.

Independent review. For certain types of development in Scotland, SEPA requires the FRA to be independently reviewed by a suitably qualified professional. This is not a standard requirement in England.

Technical Requirements for FRAs

England

The EA’s requirements for FRAs are set out in the PPG and the EA’s published guidance. Key requirements include:

• Assessment of flood risk from all sources
• Application of EA climate change allowances (specific percentages by river basin, time horizon, and allowance category)
• Finished floor levels at least 300mm above the design flood level (with climate change)
• Safe access and egress during the design flood event
• No increase in flood risk elsewhere
• Demonstration that the Sequential and Exception Tests are passed (where applicable)

Scotland

SEPA’s requirements are set out in its Technical Flood Risk Guidance. Key requirements include:

• Assessment of flood risk from all sources
• Application of climate change allowances based on UKCP18 projections
• Finished floor levels at least 600mm above the design flood level (SEPA’s standard freeboard is 600mm, compared to the EA’s 300mm)
• Safe access and egress — SEPA generally requires dry access above the 0.5% annual probability flood level
• No increase in flood risk elsewhere
• Assessment of the development’s vulnerability in accordance with SEPA’s Land Use Vulnerability Guidance

Key technical differences:

Freeboard. SEPA requires 600mm of freeboard above the design flood level; the EA typically requires 300mm. This is one of the most significant practical differences, as it affects finished floor levels, building design, and site levels.

Design flood event. SEPA uses the 0.5% annual probability event (1 in 200 year) as the standard design event for river and coastal flooding. The EA uses the 1% event (1 in 100 year) for river flooding and the 0.5% event for coastal flooding. This means that the baseline flood level in Scotland is typically higher than in England (before freeboard is applied).

Climate change allowances. The EA publishes location-specific climate change allowances as percentage increases to peak river flow. SEPA’s approach is less prescriptive, requiring the FRA to consider a range of climate change scenarios based on UKCP18.

Modelling standards. Both SEPA and the EA accept standard hydraulic modelling software (TUFLOW, Flood Modeller, HEC-RAS). However, SEPA has specific requirements for model setup, calibration, and reporting that differ in detail from the EA’s.

Drainage and SuDS

England

In England, the LLFA is the statutory consultee for surface water drainage on major development. The drainage strategy must follow the SuDS hierarchy (infiltration, watercourse, surface water sewer, combined sewer), and the LLFA reviews the strategy against national and local requirements.

From 2024, the government has signalled its intention to implement Schedule 3 of the Flood and Water Management Act 2010, which would create SuDS Approving Bodies (SABs) in England. However, as of early 2026, Schedule 3 has not yet been commenced in England.

Scotland

In Scotland, Scottish Water is the statutory water and sewerage authority, and surface water drainage connections are managed through Scottish Water’s development process. The key differences are:

Scottish Water’s “right of connection.” Developers in Scotland have a right to connect surface water drainage to the public sewer network, subject to Scottish Water’s requirements. This is subtly different from England, where the right of connection exists but water companies can negotiate discharge rates.

Surface water connection policy. Scottish Water has published guidance on surface water connections, encouraging SuDS and limiting connections to combined sewers. Their “Sustainable Development” criteria apply to all new development connecting to the public network.

No SABs in Scotland. Scotland has not implemented SAB-equivalent bodies. Instead, drainage approval is managed through the planning and roads construction consent processes, with input from Scottish Water and SEPA.

Roads construction consent. For development that includes roads to be adopted by the local authority, the roads authority (the council) reviews the drainage design as part of the roads construction consent process. This adds an additional layer of approval that does not exist in the same form in England.

Practical Implications for Developers

Working in Both Jurisdictions

If your development portfolio spans England and Scotland, be aware that:

• FRAs must comply with different standards. An FRA prepared to EA standards will not necessarily satisfy SEPA’s requirements, and vice versa. Ensure your flood risk consultant is experienced in the relevant jurisdiction.
• Timescales differ. SEPA’s consultation process can be slower than the EA’s, particularly for complex sites. Factor this into your programme.
• Technical requirements differ. Higher freeboard requirements in Scotland can affect building design, site levels, and construction costs. Address these requirements early in the design process.
• Drainage approval routes differ. The role of Scottish Water, the LLFA (England), and the roads authority (Scotland) differ significantly. Understand which bodies need to approve the drainage design and engage with them early.

Cross-Border Projects

For development sites that straddle the England-Scotland border, or that have flood risk implications on both sides of the border, engagement with both SEPA and the EA is required. These are rare but can be complex.

Choosing a Consultant

When selecting a flood risk or drainage consultant for projects in Scotland, check that they have specific experience of working with SEPA and the Scottish planning system. The technical and policy differences are significant enough that generic “UK-wide” experience may not be sufficient.

How Aegaea Can Help

Aegaea prepares Flood Risk Assessments and drainage strategies in both England and Scotland. Our team includes engineers experienced in both the EA and SEPA consultation processes, and we understand the technical and policy differences between the two jurisdictions.

Whether you are developing in England, Scotland, or both, we provide the jurisdiction-specific expertise needed to navigate the flood risk and drainage requirements efficiently.

Contact us to discuss your project.