 It was stated in a statuary report, under the Reservoir Safety Act 1975, dated 12 June 1984, that all five reservoirs could be over-topped during a Probable Maximum Flood, so major works were undertaken.The retention level was raised by , the embankment crest by , and the wave wall was rebuilt.An wide auxiliary spillway was constructed, two new butterfly valves installed and existing valves descaled and motorised.