Essex Rivers Hub

Roman River Catchment Overview

The total length of river within this catchment is 35.9km, consisting of the following water bodies: Layer Brook 14.8km, Roman River 18.1km and Virley Brook 3km.

The Water Framework Directive (WFD) status for both of these water bodies within this catchment is Moderate Potential. Phosphate levels are classed as bad for all but the Roman River, which is still classed as poor. Generally water quality is otherwise good, except for Layer Brook which has high levels of ammonia, and also low dissolved oxygen levels.

Virley Brook has had the least data collected which means that biological classification cannot be commented on at this stage. Morphology is currently classified as moderate, due to historical modifications, but other than this, the only identified issues are those with phosphate.

Layer Brook currently has little information about it with further data needing to be collected. It has a moderate classification for both fish and hydrology. Abberton Reservoir is situated within this water body, recent maintenance activities have caused an increase in the level of sediment in the water, which could be causing the problems that are present for fish. It is likely that there are problems with flow due to Abberton Reservoir abstractions, therefore causing this moderate classification. In order to prevent further issues caused by these abstractions, mitigation measures were put in place. Unfortunately these measures were not taken forward, so still remain park of future objectives:

  • Ensure the rate and range of any artificial drawdown is appropriately managed to maintain aquatic plant and animal communities in the shore zones of water storage and supply with gently shelving shore zones.
  • Ensure the seasonal pattern of water levels during each year is managed so as to enable the establishment and retention of aquatic plant and animal communities in the shore zone of the impoundment.

 

The Roman River has been investigated more than Layer Brook and apart from phosphate, only has issues with fish and diatom (plants smaller than the eye can see) levels, which are both classed as moderate. The reason for the diatom classification has not yet been determined, however, high phosphate levels could be contributing to this. Fish levels are lower than expected due to a combination of high sediment loads, and the upper and lower reaches of the river not maintaining the high standards that the middle section has. In order to fix these issues, many mitigation measures were suggested, but these were unfortunately not put in place:

  • Appropriate channel maintenance strategies and techniques - minimise disturbance to channel bed and margins
  • Appropriate channel maintenance strategies and techniques - woody debris
  • Improve floodplain connectivity
  • Increase in-channel morphological diversity
  • Retain marginal aquatic and riparian habitats (channel alteration)
  • Operational and structural changes to locks, sluices, weirs, beach control, etc.
  • Set-back embankments
  • Structures or other mechanisms in place and managed to enable fish to access waters upstream and downstream of the impounding works

 

Moreover, as part of their ongoing efforts to prevent the pollution of river water, the Environmental Agency considers the following pesticides to be risks and must therefore be carefully managed through Safeguard Zone Action Plans, to protect raw water sources that are used to provide drinking water:

  • Metaldehyde - An organic pesticide used against gastropods in both household and agricultural settings. It is mildly toxic when consumed by other organisms, especially predators of gastropods (hedgehogs, frogs, wild birds), and has been linked to their decline. Read more.
  • Carbetamide and propyzamide - these are herbicides used for winter oilseed rape and winter field beans which target various annual grasses and broad-leaved weeds. They pose no known risk to mammals, birds and bees but are highly toxic to aquatic organisms.

 

As always, local water companies will continue to strive to abide with EU regulations as studies have shown that metaldehyde, carbetamide and propyzamide pose a very low risk to human health in low doses.

 

 

 

 

 

 

 

 

 

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