The general Risk Management Authority (RMA) responsibilities in relation to flood risk and surface water management are outlined below:

The Environment Agency (EA) is responsible for managing flood risk from the sea, main rivers and reservoirs and has a strategic overview role for all flood risk management. It is a key local partner for Dorset Council, especially when managing the risk from combined sources and in the event of a large flood incident. The EA also provides a flood warning service throughout England and Wales in areas at risk of flooding from main rivers or the sea.

Dorset Council as the Lead Local Flood Authority (DC LLFA) is responsible for the management of flood risk from local sources, including ordinary watercourses, groundwater and surface water runoff. It is also responsible under the Land Drainage Act 1991 for consenting works and enforcing the removal of any unlawful structure or obstruction within ordinary watercourses. The LLFA must also prepare a Local Flood Risk Management Strategy, maintain a record of flood risk assets and undertake investigations. It is also a statutory planning consultee for the management of surface water drainage to major development sites (ten or more houses and commercial development of floor space greater than 1000m2 or sites larger than 1Ha).

Since merging with the District Councils in April 2019, certain functions and responsibilities now come under Dorset Council as the new Unitary Authority. For example, the preparation of Development Plans, and offering discretionary comments regarding flood risk on minor planning applications. There are also powers under the Public Health Act 1936 to ensure the removal of any blockage within an ordinary watercourse that is considered a nuisance.

Dorset Council as the Highway Authority (DC HA) maintains the highway drainage system to reduce the amount of surface water generated on the highway. This is achieved by managing surface water via the maintenance of highway drainage infrastructure.

Water and Sewerage Companies (Wessex Water) Water and Sewerage Companies are responsible for managing the risks of flooding from surface water and foul or combined sewer systems including drainage from buildings and yards.

Highways England (HE) is responsible for managing, maintaining and improving the motorways and trunk roads across England and any associated drainage and flood risk.

Risk Management Authority Responsibilities

Flood source - rivers

  • main river - Environment Agency
  • ordinary watercourse - Dorset Council - LLFA

Flood source - surface water run-off

  • surface water - Dorset Council - LLFA
  • surface water from highway - Dorset Council - Highways


  • sewer flooding- Wessex Water
  • the sea - Environment Agency
  • groundwater - Dorset Council - LLFA
  • reservoirs - Environment Agency

All RMAs have a duty to co-operate and to share information in relation to their flood risk management functions.

  • Land/Property Owners that have a watercourse in or adjacent to their land have riparian responsibilities on that watercourse. This means the landowner must:
  • let water flow through their land without any obstruction, pollution or diversion which affects the rights of others.
  • accept flood flows through their land, even if these are caused by inadequate capacity upstream.
  • keep the banks clear of anything that could cause an obstruction and increase flood risk, either on their land or downstream if it is washed away.
  • maintain the bed and banks of the watercourse and the trees and shrubs growing on the banks and should also clear any litter or debris from the channel and banks, even if it did not come from their land and to keep any structures, such as culverts, trash screens and debris grills, weirs and mill gates, clear of debris.

Share this page