Thames Water Blitz - Lower Windrush Valley

The 8th Thames Water Blitz took place on 26th - 29th April 2019, involving hundreds of volunteers carrying out quick and easy to use tests for phosphates and nitrates in ponds, lakes, ditches, streams and rivers across the Thames catchment.

The testing can help give a snapshot of water quality across a catchment, raise awareness about nutrient pollution and create data for use by scientists, policy makers, land managers, catchment partnerships and local communities.

LWVP volunteers tested 28 sites across the Lower Windrush, the results are summarised here:

The good news is that these results support the findings of more focused surveys coordinated by LWVP in 2016 and 2017 - lakes and ponds in the Lower Windrush Valley are an important clean water resource. Most are fed by groundwater flowing very slowly through gravel, which helps keep the water clean and free from nutrient pollution, and allow freshwater wildlife to flourish.  The bad news is that, like in most areas of lowland Britain, the majority of streams and rivers suffer serious nutrient pollution.

Full results of the Thames Water Blitz, including those from the Lower Windrush Valley, can be viewed via an interactive map on the Freshwater Watch website: https://freshwaterwatch.thewaterhub.org/totally-thames-water-blitz

Case Studies from the Lower Windrush Valley surveys conducted in 2016 and 2017 can be found on our website here: https://www.oxfordshire.gov.uk/residents/environment-and-planning/countryside/lower-windrush-valley-project/what-we-do

Protecting Water Voles in the Lower Windrush Valley

Water Voles are Britain’s fastest declining mammal. They have lost a staggering 95% of their range since 1900. 

A Water Vole



Why have Water Vole numbers declined?
Water voles inhabit the edges of ditches, streams and rivers and make their burrows in the soft riverside banks. They feed on the reeds and grasses found nearby. The feeding and burrowing activity of voles creates favourable habitat alongside river edges for other animals and plants such as Kingfishers, who often use Water Vole excavations for nests. The impacts of the loss of this habitat on Water Voles is huge, and it has been exacerbated by predation from North American Mink.
The North American Mink is not native to Britain, but they are now widely established throughout the UK, largely due to escapes and releases from Mink farms in the 1950’s. Mink can have a devastating impact on our native fauna, and the decline in Water Vole populations is directly linked to predation by Mink. Mink are successful predators of Water Vole because they can swim well and are small enough to enter Water Vole’s burrows. 

Water Voles in the Lower Windrush

The Lower Windrush is designated as a Local Key Area for Water Voles, and Water Vole presence has slowly extended along both arms of the Lower Windrush Valley since a population were reintroduced in 2005. In fact, the results of the most recent survey, in 2016, found that Water Vole activity was only absent in areas with unsuitable habitat. Of particular good news is that Water Vole activity has been detected in the area immediately above the confluence with the River Thames, linking the Lower Windrush Valley to other Local Key Areas nearby, effectively creating one extensive Local Key Area for Water Voles.




A Water Vole in the Lower Windrush

Mink monitoring and control in the Lower Windrush
Monitoring for the presence and control of Mink is carried out in the Lower Windrush Valley using Mink rafts provided by The Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust (BBOWT). The rafts have a tray of soft clay, positioned in areas where Mink are likely to be present. The Mink pass across the clay and leave footprints, indicating their presence. Possible Mink prints were recorded in ten different areas of the Lower Windrush Valley during a 2016 survey.



Mink prints on clay from a raft near Standlake


There are currently Mink rafts in the Ducklington area but controlling populations in the lower end of the Windrush is particularly important to reduce the number of Mink travelling upstream from the River Thames.  


New Mink rafts in place!
As of May 2019, a further three Mink rafts are now in place and a new team of volunteers have begun to monitor the rafts on a weekly basis. If Mink prints are identified during monitoring visits, then a trap will be deployed. Once a Mink has been captured, it will be humanely killed following best practise guidelines.


One of the new rafts in position



Volunteers helping to put a new raft in position


Further information
Lower Windrush 2016 Survey Report: https://www2.oxfordshire.gov.uk/cms/sites/default/files/folders/documents/environmentandplanning/countryside/protectedspecies/WaterVoleUpdate-LowerRiverWindrush2016Report.pdf
Lower Windrush 2016 Survey Map: https://www2.oxfordshire.gov.uk/cms/sites/default/files/folders/documents/environmentandplanning/countryside/protectedspecies/WaterVoleUpdate-LowerRiverWindrush2016Map.pdf
BBOWT Water Vole Recovery Project webpage: https://www.bbowt.org.uk/wildlife/wildlife-conservation/water-vole-recovery-project