Elevated nutrients coming from a sewage treatment works in the Upper Mun is thought to be limiting stream invertebrate biodiversity and polluting a lake downstream. The restoration will divert the stream water through a series of shallow plant-filled lakes so that the excessive nutrients coming from the sewage treatment works are converted to plant biomass, thus providing a filtering system. Stream habitat will also be diversified using LWD (large woody debris) and through the creation of backwater habitat. These new features will provide areas for slack water-associated organisms, while also increasing water velocity in localised areas adjacent to the LWD structures affording habitats for fast water dwelling species. Using a BACI monitoring design similar to The River Nar project , ENSIS aim to assess ecological response to the restoration

Objectives: The purpose of the project is to determine:

  1. What effect the river restoration works have had on stream invertebrate community composition, biomass and density
  2. Whether, nested within the overall change resulting from stream diversion, any specific changes in the invertebrate community have been brought about by introduction of large woody debris

Methods: ENSIS surveyed river invertebrates including a control site and downstream of the Froghall STW (treatment site). One sampling run was carried out prior to completion of the river restoration work, and one afterwards (September 2014). Invertebrate surveys were quantitative, allowing the assessment of compositional change, density and biomass. ENSIS carried out species identification and data analysis.

Results/Conclusions This project is ongoing

Links:

ENSIS river restoration

Community volunteers involved in pioneering river clean-up project, Eastern Daily Press 4th November 2014

Norfolk Rivers Trusts website

River Mun Restoration
Volunteers help plant aquatic plants at the River Mun in Northrepps to help with water quality improvement © Murray Thompson