East Cambridgeshire District Council Water Cycle Study Detailed ...

Stage 2 Water Cycle Study: Final Report
Sept 2011
2
Cambridgeshire Horizons
East Cambridgeshire – Detailed WCS
hence growth should not be seen as a barrier to watercourses in the District meeting ‘Good Status’ in the
future.
Ecological impacts on Designated Sites
There are three statutory designated sites which were identified in the outline WCS as being connected to
WwTW discharges in East Cambridgeshire – Wicken Fen SAC/Ramsar site/SSSI/LNR, Ouse Washes
SAC/SPA/Ramsar site/SSSI and Cam Washes SSSI. There is one County Wildlife Site (New River/Monks
Lode) which is linked to a wastewater treatment works.
Wicken Fen SAC/Ramsar site/SSSI/Local Nature Reserve
Burwell WwTW discharges to the Catchwater Drain which itself drains to Burwell Lode. Wicken Lode flows
into Burwell Lode at the south-west corner of Wicken Fen. It is theoretically possible for water to backflow
from Burwell Lode into Wicken Lode, but the EA in their RoC considered this a low eventuality. There is
thus no evidence on which to conclude that discharges to Burwell Lode associated with the increase in
discharges from Burwell WwTW will have any impact on Wicken Lode or Wicken Fen.
Cam Washes SSSI
Burwell Lode joins Reach Lode approximately 1km upstream of the River Cam which is the watercourse
into which Reach Lode drains. The Cam Washes are offline meadows which depend upon seasonal
inundation from the River Cam to maintain their ornithological interest. Burwell and Bottisham WwTW’s will
both require changes (or a new solution) to their discharge consents to ensure ‘no deterioration’ in the
quality of the receiving watercourses as a result of the increased discharge volumes from each WwTW.
However, given that Burwell WwTW and Bottisham WwTW make a relatively small contribution to
phosphorus loads in the downstream River Cam, it is reasonable to conclude that the upgrades necessary
to achieve ‘no deterioration’ in the receiving watercourse should adequately address the WwTW’s
individual contribution to phosphorus loading in the River Cam.
New River/Monks Lode County Wildlife Site
Monks Lode contains a number of fish species including spined loach, bitterling, bream, dace, eel, perch,
roach and pike. The Outline Water Cycle Study identified a potential connection between discharges of
Burwell WwTW and the New River via Catchwater Drain which is the receiving watercourse for the WwTW.
Further scrutiny for the Detailed WCS has identified that the prevailing direction of flow will in fact prevent
significant backflow into the New River and there is thus no evidence of a connection between Burwell
WwTW and Monks Lode.
Ouse Washes SAC/SPA/Ramsar site/SSSI
The EA RoC process concluded in the Stage 4 Report that ‘the water quality in the Hundred Foot Drain is
dominated by the water quality upstream of Earith in the Bedford Ouse Catchment. Phosphate
concentrations do not increase along the course of the Hundred Foot River, suggesting that inputs from the
STWs in the East Cambridgeshire study area are having little or no effect on water quality within this
watercourse. In addition the connection between the Hundred Foot River and the designated SAC rivers is
limited meaning water quality in the Hundred Foot River is unlikely to significantly influence the Old
Bedford Ouse’. The RoC therefore ultimately concluded that there was no amendment required to the
existing consents. The current evidence therefore does not indicate that existing phosphate discharges
from the WwTWs in East Cambridgeshire are likely to be having an adverse effect upon the Ouse Washes
SAC/SPA or SSSI.
Before changes to the consents for relevant WwTWs are made, it is necessary to determine which
WwTWs that discharge to tributaries of the Hundred Foot River are likely to require changes to their
consented discharge volumes and quality standards and whether this will result in a change to the existing