Thames River Watch gives Londoners a way to protect and monitor the health of the river Thames. We do this by training volunteers as citizen scientists to collect data on the types of plastic litter in the river and to monitor and communicate water quality issues. Since the autumn of 2014, volunteers have collated around 1500 measurements that provide a vital contribution to our understanding of the Thames' health.

The data collected in the programme allows Thames21, alongside others, to campaign for better protection. Our latest reports have helped to raise awareness about the issue of plastic packaging in the river and build the case for action. Volunteers don't need any prior knowledge to help out. Our free one day training course covers everything they need to know, including how to record your results online.

Image credit: Thames21

Cartographer map: Thames21 water quality data gathered since 2015