Essex Rivers Hub

This catchment only consists of the River Pant which is 19km in length.

This water body has a Water Framework Directive classification of moderate and is failing due to phosphate and dissolved oxygen levels, diatom (plants not visible to the naked eye) presence, lack of natural structure to the channel and problems with flow. On a more positive note this water body has good populations of fish and aquatic invertebrates and low levels of ammonia.

Phosphate has a WFD status of poor within the Pant and the sources of this have been identified as the Ely Ouse transfer Scheme (this is where water is fed into the Pant from these rivers to increase water availability within this catchment). This transfer scheme brings with it phosphates picked up in the other catchments, depositing them in the Pant. This is not the only source; phosphate has also been linked to agriculture and rural land management as well as a possible impact from effluent from point source pollution. More investigation is needed to determine the full impact of the Ely Ouse transfer scheme and also to look into point source pollution and the exact areas of concern, such as sewage treatment works and private discharges. Work should also be done with rural land managers to help them reduce their impact.

Dissolved oxygen has a WFD classification of poor in this catchment, which is an improvement from 2011 when it was classified as bad, and some of the reasons for this are natural. The levels have a seasonal pattern and are particularly low in summer and early autumn when flows are at their lowest and temperatures are high. This mixed with high levels of effluent, that has less dilution potential due to the low flows, can impact on the levels of oxygen within the water significantly. As fish and aquatic invertebrate populations are now at good levels it seems that this is not having a significant impact on species populations.

Diatoms have a WFD classification of moderate and this has been linked to the phosphate levels within this river. Therefore measures to reduce phosphates will have a favourable impact on these plants. It is possible that new data and investigations will reveal no failure for diatoms in the next round of results.

The structure of the river, or morphology, has been classified as moderate and also as heavily modified. This indicates that there are limited natural features within the channel such as meanders (curves and bends), variation in channel width and depth, etc. This can be addressed by looking at the mitigation measures that are not in place and determining if these are suitable and should be taken forward.

Flow or hydrology has a WFD classification of 'not high' so some improvement is needed here and is one of the causes of failure for dissolved oxygen. This is likely linked to the heavily modified nature of this water body so mitigation measures could also help here to improve flow in some cases.

Mitigation measures currently not in place are as follows:

  • Re-engineering of the river where the flow regime cannot be modified
  • Appropriate channel maintenance strategies and techniques – minimise disturbance to channel bed and margins
  • Ensure there is an appropriate baseline flow regime downstream of the impoundment.

 

 

 

 

 

 

 

 

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