Grafham Water is a reservoir with a circumference of about 10 miles. The lake was created by filling a valley full of water which is retained by an earth and a concrete dam built in 1965. The reservoir was immediately colonised by wildlife and a nature reserve surrounding the western side of the reservoir was soon created. Grafham Water, now owned and managed by Anglian Water, is popular for a range of leisure activities including boating,fly fishing and cycling.
We only walked a very short part of the 10miles - from Plummer Park to the Marlow Park and back again
About half way we came to the Valve Tower which is accessed via a long access bridge.