It turns to the north and then west and is again culverted, before entering a tunnel under the Leeds and Liverpool Canal and junction 13 of the M65 motorway, emerging next to Nelson and Colne College and shortly after flowing into Pendle Water.

[5] The name possibly originates from a contraction of the Old English words wælla (stream) and fyrhþ (frith),[c] with denu (valley).

[2] The first Ordnance Survey map of the area, published in 1848, shows a corn mill with a pond at what was still the small village of Bradley (today the centre of town).

[e][9] By the time Nelson developed into a mill town water-power had given way to the steam engine, however these still required a good supply of water.

[10] Although the act that authorised the creation of a compensation reservoir passed in 1866, construction was delayed as all the tenders exceeded the budget of £3196.