Non statutory reservoirs – a journey of discovery

The National Trust owns some 200 reservoirs, of which 47 are Statutory Large Raised Reservoirs; of the remainder circa 40 are thought to have volumes in the range 10,000 m3 to 25,000 m3. The reservoirs were mostly built in the 18th, 19th or 20th centuries, when construction methods were both varied and evolving. They have therefore never been fully assessed against modern dam engineering standards. The National Trust has endeavoured to identify and manage all its non-statutory reservoirs with a view to understanding the risk they pose, assessing investment requirements, their significance within the landscape and developing appropriate management and monitoring practices to ensure dam safety. With the likely change in threshold for registration with the regulator on the horizon the Trust has reviewed its non-statutory reservoir assessments and collected a number of common challenges and themes which appear regularly across its portfolio. These range from working within complex heritage designations, tree and vegetation management, through to better understanding of the resilience of reservoirs in small catchments. This paper aims to share some of this knowledge and raise some questions about potential future regulation and management of reservoirs. This paper contributes to UN Sustainable Development Goal 9 on Infrastructure and Goal 15, Life on Land.