The Environment Agency keeps a public register of the 2,102 (1,899 in England) large raised reservoirs which are capable of holding 25,000m3 or more of water above natural ground level. The Environment Agency is the enforcement authority for the Reservoirs Act 1975 in England and Wales.
The register does not contain details of the systems for releasing water from the reservoirs. However, most reservoirs do have such systems for operation and maintenance purposes.
The Environment Agency is the operator for 182 flood storage reservoirs in England. The purpose of these reservoirs is to provide storage for excess rain.