New River Corridor Studies Published

Greater Manchester Combined Authority commission a River Corridor Study of the Whittle Brook Catchment in Bury and Rochdale.

Findings and recommendations will inform the strategic and detailed planning of the Heywood-Pilsworth development.

Whittle Brook runs through mostly agricultural land between Bury and Rochdale in Greater Manchester and the catchment includes Brightley Brook and Castle Brook.  It is a tributary of the River Roch, which in turn feeds into the River Irwell.  It is important to understand and improve these headwaters because what occurs here impacts all the rivers downstream.

Whittle Brook is one of a few Waterbodies in the Irwell Catchment not designated as heavily modified by the EU Water Framework Directive (WFD), whilst several of the WFD classifications currently only have a ‘moderate’ status whereas the target is ‘good’.  We wanted to examine this Waterbody because an earlier Natural Course report found that some of the Reasons For Not Achieving Good Status (RFNAGS) were unknown, that there were barriers to fish migration, and that there was excessive suspended sediment.  The waterbody is also of interest because an earlier Natural Flood Management (NFM) Opportunity Mapping also carried out as part of Natural Course identified this waterbody as a priority for NFM interventions.

In response to these reports, Greater Manchester Combined Authority (GMCA) commissioned a study of the current ecological value of, and WFD pressures and opportunities on, Whittle Brook, Castle Brook, and Brightley Brook.  A targeted site-based Integrated Riparian Survey (IRiS) with UK Habitat Classification System (UKHab) survey was carried out, including a desk-based geomorphological and ecological assessment. This assessment covered the rivers, their floodplain and the processes that control sediment availability along the system.  In addition, a natural capital approach was applied to evaluate the wider opportunities that could be delivered as part of the development of the site.

The proposals in the report aim to improve the WFD status of the waterbodies as well as increasing the ecological value via providing additional habitats, such as backwater features, wet woodland, riparian buffers for protected/notable species and improving species-richness.  It was also recommended to take steps against invasive species such as Himalayan balsam and Japanese knotweed that are present within the catchment.  Altering the river management by such actions as regrading banks can reduce sediment runoff into the watercourses. Flood regulation is also potentially supplemented at Whittle and Brightley Brook with additional planting and floodplain connectivity increasing infiltration into the surrounding areas resulting in reduced peak flows.

Much of the area of the study is within the Heywood-Pilsworth allocation of the Places For Everyone Joint Development Plan.  This strategic-scale development will provide opportunities to implement the suggested environmental enhancements.  Meanwhile, advice given to land managers will help them prevent sediment and other pollutants from entering the brooks.

Natural Course Project Officer Mike Beard said…

“Up to now we knew that these rural headwaters had environmental problems but not precisely why.  Thanks to this study we now have a much better idea of their causes, as well as practical suggestions to assist resolution of those issues.  The land managers can benefit from expert recommendations, and we have added to the list of available options for enhancing environmental benefits during the build out of the large-scale Heywood-Pilsworth allocation.”

You can read the full river corridor study here: https://naturalcourse.co.uk/uploads/2021/07/RiverCorridorStudy_Main_FINAL_compressed.pdf

You can find the ecosystem services assessment scoping report here: https://naturalcourse.co.uk/uploads/2021/07/RiverCorridorStudy_ESS_FINAL.pdf