River Dunsop
It begins at the confluence of the Brennand River and Whitendale River, both of which rise high up in the surrounding moorland. It then flows through the steep-sided Dunsop Valley before meeting the Hodder. An aqueduct carrying water to Blackburn runs alongside.
The Dunsop drains a catchment approximately 9 km by 5 km, which comprises the sub-catchment areas of the Brennand and Whitendale, and is classed as a fifth order catchment. The catchment is primarily Millstone Grit, but the tributaries run through older shale and limestone strata
On 8 August 1967 Dunsop Valley entered the UK Weather Records with the Highest 90-min total rainfall at 117 mm. The peak flow of the flood was deduced primarily from wrack mark evidence and roughness coefficients. As of July 2006 this record remains.