Essex Rivers Hub

This catchment consists of the River Roach and Prittle Brook. The Roach is made up of 2 main tributaries, which are Nobles Green Ditch to the north and Eastwood Brook to the south, these three water bodies have a total length of 21km. Prittle Brook flows into the Roach Estuary and has a length of 6km.

The Water Framework Directive classification for this catchment is moderate and it is failing for phosphate and aquatic invertebrates throughout but is also failing for ammonia, river structure and flow within Prittle Brook. The Roach and associated tributaries are also failing because some mitigation measures are still outstanding. On a positive note the whole catchment has good fish populations and good dissolved oxygen levels and the Roach and its associated tributaries has good flows and low ammonia levels (a part from Nobles Green Ditch where the sewage treatment works is having a large impact).

Phosphate is a catchment wide impact. The Roach and associated tributaries have a WFD status of bad, while Prittle Brook has a slightly improved status of poor. Within the Roach the exact causes are not clear but the sewage treatment works will be having an impact, more investigation is needed to determine the exact sources. In Prittle Brook, point and diffuse pollution sources have been identified. Work needs to be done with Anglian Water to identify sewage overflow hotspots and misconnections. Permitted drainage also needs to be looked into for this water body to determine if these need to be reviewed and then continued investigation into the areas that have the highest impact.

Aquatic Invertebrates are also a catchment wide failure. In the Roach and associated tributaries it has a WFD classification of moderate for these invertebrates whereas within Prittle Brook it is significantly lower with a classification of bad (the lowest status possible). The catchment wide reason for failure is diffuse and point source pollution and has a direct correlation to phosphate pollution. Within this catchment inputs from sewage treatment works and urban drainage are having a significant impact on invertebrate populations. Within Prittle Brook an additional pressure on invertebrate populations is the effects of urbanisation that has resulted in long stretches of this water body to become completely concrete lined, reducing all suitable habitats that aquatic invertebrates need to survive.

Morphology (river structure) and ammonia have a WFD classification of moderate within Prittle Brook. There are mitigation measures that are outstanding that could address morphology so these need to be assessed to see if they are still feasibility and action those that are appropriate. Ammonia was classified as high in 2011 but that has now deteriorated to moderate. Therefore data needs to be examined and more investigations completed to ensure the moderate classification is correct. If it is accurate then the cause of the failure needs to be determined.

Hydrology or flow is classified as not high therefore investigation is needed to determine what the reasons are and actions taken to improve flows.

Mitigation measures are another catchment wide failure as not all measures have been implemented. The following measures are not yet in place:

  • Increase in channel morphological diversity.
  • Appropriate techniques to align and attenuate flow to limit detrimental effects of these features (drainage).

 

 

 

 

 

 

 

 

Website key stakeholders:

Environment Agency logo      Essex Wildlife Trust logo           

Design by LTD Design Consultants and build by Garganey Consulting based on an original concept by Herts and Middlesex Wildlife Trust