Our sampling volunteers and testing hubs have been busy again this month with over 50 locations within the Deben catchment having water samples taken. The range of tests we do now cover not only bacterial and chemical analysis but also physical measurements such as pH, temperature and electrical conductivity. This past month we have also added the Riverfly invertebrate studies to the activities we are doing.
E. Coli - November’s results are broadly in line with previous trends; we did not find any serious pollution in the Debentidal section this month and elsewhere the high readings are mostly coming from STW outfalls. There are a couple of exceptions in downstream and upstream sections on the River Fynn and around Debenham. Both may be due to low flow but the Debenham results are being investigated further by the Debenham Green Team. On the River Fynn, we sampled for the first time at Henley, just below the Anglian Water STW and found high E.coli; at Rendlesham STW after several months with moderate E.coli this time the readings spiked at over 30,000 CFUs per 100 ml (300 colonies per 1ml).
Phosphate - the phosphate results outside the Anglian Water STW’s are generally under 1.0 ppm with the majority close to the 0.1 ppm healthy river level. The exception here are the Rivers Lark and Fynn which continue to have high phosphate readings; this may be due to low river flow and/or the presence of small sewage treatment works which have not had any investment for some years.
Phosphate: There is growing evidence that, where Anglian Water have invested in and installed phosphate removal technology, that the STW phosphate levels have tumbled in recent months and are within the new permit levels due to come into force in January 2025. The outlier is Rendlesham where phosphate levels have climbed back to those seen at the start of 2024; this plant looks unlikely to meet its permit level by the end of 2024, so we are requesting an explanation from Anglian Water and the Environment Agency.
Riverfly Surveys - since the Training Day on 1st October, our survey groups have been busy starting to conduct Riverfly invertebrate studies. We now have 8 locations set up on the UK-wide database Cartographer. Thus far, 8 surveys have been completed and approved; initial results show that aquatic life in the River Deben is relatively healthy. At Wickham Market, near Rackham’s Mill, our underwater camera recorded a stream “teeming with fish”. This is good news for our river and the potential for its recovery.
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