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Class D: Development by the Environment Agency
Class D gives the Environment Agency specified permitted development rights for its functions, including underground water-resource works, watercourse and drainage maintenance, surveys and flow measurement.
There are important limits on reservoirs, new buildings, alterations and plant. Survey equipment is temporary.
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Limits and temporary work
D(a) does not permit building a reservoir. D(f) covers some development on operational land but not a new building; the height, external appearance, volume and floorspace of altered buildings and the height of plant are restricted.
For D(c) surveys, operations cease and equipment is removed at completion or after six months from commencement, whichever is sooner, followed by restoration as soon as reasonably practicable. See Part 13, Class D and the general limits.
Legislation
Class D – development by the Environment Agency
Permitted development
D. Development by the Environment Agency for the purposes of its functions, consisting of—
(a) development not above ground level required in connection with conserving, redistributing or augmenting water resources;
(b) development in, on or under any watercourse or land drainage works and required in connection with the improvement, maintenance or repair of that watercourse or those works;
(c) the provision of a building, plant, machinery or apparatus in, on, over or under land for the purpose of survey or investigation;
(d) the maintenance, improvement or repair of works for measuring the flow in any watercourse or channel;
(e) any works authorised by or required in connection with an order made under section 73 of the Water Resources Act 1991 (power to make ordinary and emergency drought orders);
(f) any other development in, on, over or under their operational land, other than the provision of a building but including the extension or alteration of a building.
Development not permitted
D.1 Development is not permitted by Class D if—
(a) in the case of any Class D(a) development, it would include the construction of a reservoir;
(b) in the case of any Class D(f) development, it would consist of or include the extension or alteration of a building so that—
(i) its design or external appearance would be materially affected,
(ii) the height of the original building would be exceeded, or the cubic content of the original building would be exceeded by more than 25%, or
(iii) the floor space of the original building would be exceeded by more than 1,000 square metres; or
(c) in the case of any Class D(f) development, it would consist of the installation or erection of any plant or machinery exceeding 15 metres in height or the height of anything it replaces, whichever is the greater.
Condition
D.2 Development is permitted by Class D(c) subject to the condition that, on completion of the survey or investigation, or at the expiration of 6 months from the commencement of the development concerned, whichever is the sooner, all such operations cease and all such buildings, plant, machinery and apparatus are removed and the land restored as soon as reasonably practicable to its former condition (or to any other condition which may be agreed with the local planning authority).
Page updated: 24th September 2026