Named because the high proportion of iron in the rocks of the Great Whin Sill, over which the sike runs, results in a red tinge to the rocks in the stream.
Before this major dam was built (post WW2), primarily to provide water to ICI and the rest of the industrial area at the mouth of the Tees, there was a 'ghastly, serpentine lake' (the cauldron of Cauldron Snout) here - known locally as 'The Weel'.