The River Gade is a river running almost entirely though Hertfordshire. It rises from a spring in the chalk of the Chiltern Hills at Dagnall, Buckinghamshire and flows through Hemel Hempstead, Kings Langley, then along the west side of Watford through Cassiobury Park. After passing Croxley Green it reaches Rickmansworth, where it joins the River Colne. For its whole course the Gade is unnavigable.