Consents
If your works affect a watercourse, planning permission is not the only consent you need. Ordinary watercourse consent is separate, it is a legal requirement, and getting it late can stop a job that is already on site.
It is the consent most often missed, because nothing in the planning process necessarily tells you that you need it.
Ordinary watercourse or main river?
Which body you apply to depends on how the watercourse is classified, and the two routes are entirely separate:
- Ordinary watercourse — every ditch, brook, stream, drain, culvert and dike that is not designated a main river. Consent comes from the lead local flood authority, or from the internal drainage board where the site sits inside an internal drainage district.
- Main river — designated watercourses shown on the Environment Agency’s main river map. Works in, over, under or within a set distance of the bank need a flood risk activity permit from the Environment Agency instead.
Plenty of sites have both. A culverted brook running through a development can be an ordinary watercourse along its length and join a main river at the boundary, and the two consents are applied for separately.
When consent is required
Under section 23 of the Land Drainage Act 1991, written consent is needed before you erect a culvert in an ordinary watercourse, or alter an existing culvert in a way likely to affect the flow. More broadly, any works that obstruct the flow within the channel need consent — including temporary works.
The practical test authorities apply is a useful one to hold in mind: would the works affect the flow when the watercourse is full to the top of the bank? If the answer is yes, consent is needed.
Things that commonly need it
- Culverting an open ditch, or extending an existing culvert
- A new or altered headwall, outfall or discharge structure
- A flow control device, penstock or orifice plate in the channel
- A bridge, crossing or access over a ditch
- Diverting, regrading or infilling a watercourse
- Temporary works — a piped crossing for construction traffic, or a dam for dewatering
A new surface water outfall discharging into a ditch is the one that catches most developments. It is a very ordinary part of a drainage strategy, and it needs a consent of its own.
Why it matters more than it looks
Carrying out works without consent is an offence, and the authority can require the works to be removed or altered at your cost. Because it sits outside the planning process, nobody is obliged to warn you — a permission can be granted and conditions discharged without the consent ever being mentioned.
It also takes time. Authorities typically quote around two months to determine an application, and most charge a fee. That is time you do not want to discover while a contractor is standing on site waiting to install an outfall.
A note on culverting
Most lead local flood authorities start from a presumption against culverting an open watercourse. Culverts increase flood risk, block up, are difficult to maintain and remove habitat. If your layout relies on culverting a ditch to gain developable area, expect to justify it thoroughly — and expect the alternative of designing the watercourse into the scheme as open channel to be raised.
That is worth knowing at layout stage rather than after a masterplan is fixed, because it moves plots.
Riparian ownership
If a watercourse runs along or through your land, you are likely to be a riparian owner. That carries ongoing responsibilities — maintaining the flow, keeping the channel clear, and not causing an obstruction — regardless of whether you are developing. Consent deals with the works; riparian responsibility does not end when they are finished.
How we handle it
When we prepare a drainage design we establish early whether the outfall involves an ordinary watercourse or a main river, and whether a consent is needed. Where it is, the application is prepared alongside the drainage strategy rather than after it, so the two run in parallel instead of one waiting on the other.
Send us the site address and we will tell you which watercourses are involved, how they are classified, and which consents your scheme will need. See also drainage planning conditions and the authorities we work with.
Source: Land Drainage Act 1991, section 23. Fees and determination periods are set locally and change — we check them for your authority at the start of the job.