Ordinary watercourse consent

If you are planning to undertake works within a watercourse within the UK, you need permission to do so by law. It is essential that anyone who intends to carry out works in, over, under or near a watercourse, contacts the relevant flood risk management authority to obtain the necessary consent before starting the work. In relation to works on an ordinary watercourse, the legal provisions are as follows:

Section 23(1) of the Land Drainage Act 1991 states: "No person shall:

(a) erect any mill dam, weir or other like obstruction to the flow of any ordinary watercourse or raise or otherwise alter any such obstruction, or

(b) erect a culvert in an ordinary watercourse, or

(c) alter a culvert in a manner that would be likely to affect the flow of an ordinary watercourse, without the consent in writing of the drainage board concerned.”

Ordinary watercourses include every river, drain, stream, ditch, dyke, cuts, sluices, culverts, sewer (other than public sewer) and passage through which water flows that do not form part of main rivers. The Environment Agency remains responsible for regulating activities affecting the coast and main rivers. It is not required for water to always flow for it to be considered as a watercourse.

For ordinary watercourses in Cambridgeshire, outside an Internal Drainage Board (IDB) area, the relevant authority is Cambridgeshire County Council (CCC). The consent granted by CCC for working on a watercourse is known as "Land Drainage Consent”. Some ordinary watercourses are under the jurisdiction of an IDB, and the IDB will be the consenting body for these watercourses. Changes to structures (e.g. dams, weirs, culverts or other such obstructions) that are already in place will also need consent from CCC or the IDB.

When considering if proposed works to an ordinary watercourse will require consent, you should consider whether the proposed structure would affect the flow of the watercourse when the channel is full. If the answer to this is yes, then consent from CCC or the IDB will be required. Consent will be required irrespective of whether works are permanent or temporary. Please note that the maximum length of time that can be consented for a temporary structure is 12 months.

The reason for the consenting process is to ensure that any proposed works do not endanger life or property by increasing the risk of flooding nor cause harm to the water environment and nature conservation. CCC will consider each application to work on a watercourse on its own merits, but it is CCC policy to keep watercourses as open channels without obstructions to flow wherever is reasonably possible. We will not permit culverting of a watercourse where there is no genuine need, or where the inclusion of a culvert would lead to an increase in flood risk in the area. In all cases, where it is appropriate to do so, applicants must provide adequate mitigation measures.

You are advised to contact the council to check whether your works will be deemed to affect an ordinary watercourse - floodandwater@cambridgeshire.gov.uk


In relation to works to culverts, our Culvert Policy should be followed.

Natural flood management

Read our natural flood management guidance.

Pre-application advice

Ordinary watercourse consenting pre-application charging schedule.

Pre-application enquiry type Access culverts less than 6m for a single householder (cost per structure including VAT at 20%) All other structures, including, but not limited to access culverts (cost per structure including VAT at 20%)
Written advice in response to a written enquiry n/a £60
Meeting and written advice with officer at the council office. General discussion of requirement, provision of info and sign-posting of further information sources; support and advice available n/a £90
Meeting on site with an officer followed by written advice £60 £120
Additional work £60 per hour plus travel expenses (£0.45 per mile)

We strongly encourage pre-application discussions and potentially site visits to discuss the appropriateness of your proposed plans and to ensure that everything you need to submit is provided when the application is made.

Making an application for ordinary watercourse works

Please read the application guidance document and apply online using the form below.