Report to Parish Council

24 th October 2020

Upper Thames Partnership – river water quality investigations

For reference: The Upper Thames Partnership (UTP) is supported by the Environment Agency, Natural , Rural Community Council, Cotswold Conservation Board, Swindon Borough Council, National Farmers Union, Thames Water, Gloucestershire Wildlife Trust, Gloucestershire County Council, Council, , Cotswold Rivers Trust, Wiltshire Council, Wiltshire Wildlife Trust, National Trust, various fisheries groups plus a number of Parish Councils along the rivers Churn, Windrush and Coln.

The purpose of the UTP is to improve the water quality of the 3 main catchment rivers feeding into the Thames. There has been a marked deterioration in the quality of these 3 rivers over the last 20 years with a corresponding deterioration in fish and other ecological features.

Since the start of the Covid lockdowns there have been no formal meetings and various training courses and briefing meetings have had to be cancelled and so far UTP has not managed to use online video conferencing to replace face to face meetings and so there has been some loss of impetus. Wendy and I have continued to monitor water quality on the River Coln mainly on a monthly basis (except during lockdown) and are reporting these findings into a national data base. Essentially, we are testing for Ammonia which is primarily an indicator of sewerage discharge and Phosphate which is broadly a measure of fertiliser run off. We also participated in the 21 st September UK National Rivers Survey which covered all the main UK rivers.

For reference, water quality is tested using the Defra/FWAG specified testing equipment purchased on behalf of Bibury Parish Council, namely Hanna photo colorimeters type HI715 Ammonia Medium Range and HI713 Phosphate Low Range meters. Each test requires the purchase and use of chemical reagents from Hanna Instruments. Such measurements are accepted as being of sufficient quality by the various agencies involved. We also make observations regarding the presence of algae growth which is regarded as indicator of excess fertiliser runoff in particular and we record turbidity (cloudiness) of river water as this considered damaging to fish and other river ecology. We also note the cleanliness of the river gravels which are vital to fish breeding.

Water samples are tested at the following locations on an approximately monthly basis

1. Ablington road bridge 2. Bibury – alongside Rack Isle 3. Approximately 100 meters below the Bibury Sewerage plant outfall on the Bibury Court Farm Estate. We have identified a further locations up stream of Bibury at Winson Mill if we find excessively poor water quality so that any sources of contamination can be better identified. We also periodically sample the spring at the Swan just to confirm it remains uncontaminated. Other groups survey river water quality and condition in the headwater of the River Coln (at and further upstream) and other parties carry out water quality surveys near .

Progress to date Anecdotally reports appear to suggest that Thames Water are taking the organised measurement programs very seriously and there appears to have been a marked improvement in water quality during the last year. Also, in all locations, Phosphate levels have general been low except for a brief increase during August and September. Also there appears to be some reduction in algae growth, gravel cleanliness has improved water clarity is much better although fish numbers do not seem to have recovered yet. We have organised some sample capture of Signal Crayfish (indigenous English crayfish have long since been irradicated by their America cousins) – in one period of about 10 days, using 3 crayfish pots, 165 signal crayfish were caught over a 10-meter stretch of the mill race leading into Arlington Mill. This is an incredible density of crayfish and the largest catch was taken on the final night of the sampling, suggesting that there were still large numbers of crayfish available. There seems little doubt that these crayfish will be having a massively damaging impact on river ecology. The crayfish eat anything they can including fish eggs, water snails, and other crayfish (they are highly cannibalistic). It is of course illegal to return Signal Crayfish into a UK river course, so all the crayfish were dispatched, and some were eaten. It seems probable that the massive increase in Signal Crayfish numbers had not only reduced the ecological diversity of the river fauna but have also increased water cloudiness (turbidity). The removal of these crayfish is to be encouraged.

I am not aware that there has been any progress on the reduction in the height of the Bibury Mill weir, no repairs have yet been made to Bibury Mill sluice gates, and no silt removed at Bibury Court/Bibury Mill. It has been difficult to reach people over recent months. Bibury Court have been repairing the embankment river wall alongside their gardens and are understood to engaging consultants regarding the river dredging/silt removal works.

Philip Challinor