After passing under the A680 Hyndburn Bridge, the brook eventually joins the River Calder, next to the district's waste water treatment works, at Martholme.

[4][5] An ongoing river improvement scheme aimed to allow migrating salmon, trout, and eels access to the River Hyndburn saw the construction of a fish bypass during 2017, at the 4-metre (13 ft 1 in) high nineteenth century Oakenshaw Print Works Weir.

[8][9] Work started on a similar project in June 2019, this being upstream at the Dunkenhalgh Weir near Rishton.

[10] United Utilities had put the two hundred metre stretch of Hyndburn Brook up for sale in February 2009, and it was being auctioned with no reserve price.

[11] Environment Agency officials praised Blythe’s Chemical Works for reducing pollution in the stretch of the brook in January 2000.