Flood risk activity permits and the 8 metre byelaw distance

If you are building, excavating or placing anything within 8 metres of the top of the bank of a main river, you need a flood risk activity permit from the Environment Agency as well as planning permission. The flood risk activity permit main river regime sits in the Environmental Permitting (England and Wales) Regulations 2016, and it is a separate consent with its own application, its own fee and its own grounds for refusal. A planning permission does not carry it, and a council cannot grant it.

The 8 metre figure is the one to remember. It applies from the top of the bank of a main river, and the same distance applies either side of a flood defence structure and either side of a culverted main river.

Which watercourses count as main rivers

Main rivers are designated and shown on the statutory main river map published by the Environment Agency. Everything else is an ordinary watercourse.

The distinction is not about size. A modest urban brook can be a main river where it carries a designated flood risk function, and a substantial field ditch can be an ordinary watercourse. Check the map rather than judging by the width of the channel.

For an ordinary watercourse the consenting body is the lead local flood authority, or an internal drainage board inside its district, under section 23 of the Land Drainage Act 1991. That is a different application with different timescales, covered in land drainage consent for works to an ordinary watercourse. Getting the two confused is the most common way a site loses six weeks.

Culverted main rivers catch people out most. A main river that has been piped beneath a car park is still a main river, and the 8 metre distance still applies to ground either side of it, even where there is nothing visible on the surface.

The 8 metre byelaw distance

Within 8 metres, the activities that need a permit cover more than building. Excavation, raising ground levels, placing a structure, planting, erecting a fence with posts, storing materials and driving plant can all require consent depending on the detail.

The reasons behind the distance are conveyance, defence integrity and access. The Environment Agency needs to be able to bring plant along the bank to maintain the channel and any defence, and it needs the floodplain and the channel to keep working hydraulically. A new building hard against the top of bank blocks all three.

Exclusions, exemptions and permits

The regime is tiered, which is worth knowing before you assume the worst.

1. Excluded activities need nothing. These are low risk works that the regulations put outside the regime altogether.
2. Exempt activities need registration with the Environment Agency rather than a permit, provided the activity meets every condition of the exemption. Registration is normally free and quick.
3. Standard rules permits apply to defined activities that can be carried out to published rules. The application is simpler and the determination faster.
4. Bespoke permits are needed for anything that does not fit a standard rules set, including most new buildings and most works to a defence.

Read the current published lists of exclusions and exemptions rather than relying on a precedent from an earlier scheme, because they are revised. Where an activity nearly fits an exemption but breaches one condition, the whole activity needs a permit, so check each condition individually.

Applying, and how long it takes

Applications go to the Environment Agency with drawings, a method statement, a hydraulic justification where the works affect the channel or floodplain, and the fee set out in the current environmental permitting charging scheme. The scheme is revised, so check the current figure rather than budgeting from last year's.

Determination periods differ sharply between standard rules and bespoke applications, and the Environment Agency publishes its target periods. Treat a bespoke permit as a matter of months rather than weeks, and build it into the programme at the point you fix your start on site date, not afterwards.

Two things shorten the process. A pre-application discussion with the local Environment Agency team, which is normally charged but worth it on anything touching a defence. And a method statement that already answers the maintenance access question, because that is the point on which bespoke applications are most often sent back for more information.

Flood defences and maintenance access

Where the site adjoins a raised defence, an embankment, a wall or a sheet pile line, the permit application is really about the defence rather than about your building.

The Environment Agency will want to know what loading the works impose on the defence, whether excavation could affect its stability or its seepage path, how the defence will be monitored during construction, how it will be reinstated, and how it will be reached for inspection and repair afterwards for the whole design life. An access strip clear of permanent structures, with a route for tracked plant and a hard standing to work from, is usually a condition rather than a negotiation.

Design the development to leave that strip from the first sketch. Retro-fitting an 8 metre maintenance corridor into a consented layout means losing plots.

Sequencing against the planning application

The permit and the planning permission are independent, and neither guarantees the other. The order that works in practice is this.

Establish the main river designation and the 8 metre line at the feasibility stage, before the layout is drawn. Prepare the Flood Risk Assessment with the permit requirement identified in it, so the Environment Agency's consultation response on the planning application and its permitting view are consistent. Hold a pre-application discussion covering both. Submit the planning application with the layout already respecting the byelaw distance. Then apply for the permit once the layout is settled, and before any works start.

Councils often attach a condition requiring evidence of the permit, or of the Environment Agency's confirmation that none is needed, before development begins. That condition is reasonable and easy to discharge if you have planned for it.

The permitting position also interacts with the surface water design, since an outfall into a main river is itself a permitted activity. Set out the outfall detail in the Drainage Strategy rather than leaving it to a later technical submission, because the headwall, the invert level and the scour protection are what the permit will control.

Where the development sits in the floodplain rather than only near the channel, resilience measures and safe access become part of the same conversation, and the approach to those is set out in residual flood risk and property flood resilience measures.

Where a permit will not be granted

Some proposals do not get through, and it is better to know which before you design around them.

Culverting an open watercourse faces a strong policy presumption against it, and the justification has to be more than convenience of layout. Building over an existing culvert is resisted for the same reasons of access and structural risk. Loss of floodplain storage without level for level, volume for volume compensation on the same site is normally refused, and compensation on land you do not control is not compensation. Works that obstruct conveyance in the channel, that impede access along the bank, or that put additional loading on a defence without an engineered solution will not be permitted.

One honest note. The Environment Agency's position on a specific defence depends on asset records and condition data you cannot see from outside, so the only reliable way to know whether a scheme is permittable is to ask, early, with drawings.

Browse all 66 PlanScope report types to see which flood and drainage documents a site beside a main river is likely to need.

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