Surveying the Waterway Environment for Pollution Threats (SWEPT)

The SWEPT project is an award-winning, volunteer led effort to collect environmental data within the Milford Haven Waterway. This data (including the results of water sample testing for nitrates and phosphates) will be used to better understand the effects of land run-off upon the marine environment, and to lead to environmental improvements.

The Waterway itself is designated as a Special Area of Conservation (SAC – a European Marine Site) and also, along the foreshore, a Site of Scientific Interest. The Pembrokeshire Marine SAC (which extends around the Pembrokeshire coast and offshore) is currently in unfavourable condition within the Waterway due in part to nutrient pollution from agricultural run-off carrying fertilizers and sewage. The Milford Haven Waterway inner section (Pembroke River and upstream) is currently failing to meet ‘Good’ status which is required for Water Framework Directive (WFD) compliance by 2027. Natural Resources Wales (NRW) routinely collect information on this but data on localised pollution sources is lacking. More data will help to identify problem areas and help to best target effective management effort. Volunteers’ data will therefore supplement NRW’s statutory monitoring and add to the evidence base upon which conservation management decisions can be taken by NRW. The data gathered will be presented in a final report as well as being provided throughout the project to NRW local staff to inform immediate pollution prevention.


Prolific opportunistic macroalgae (seaweed) growth on mudflats within the Milford Haven Waterway as a result of elevated nutrient levels. (NRW)


SWEPT is being led by the Pembrokeshire Marine SAC Officer and co-delivered with the West Wales Rivers Trust, Pembrokeshire Coastal Forum and the Darwin Centre.

SWEPT aims to improve the resilience and quality of the Waterway through improved management informed by the data and awareness raising generated by the project. Awareness raising of the issue
of land run-off affecting the marine environment is needed and will hopefully lead to behavioural changes and a reduction in nutrient pollution within the Waterway resulting in improved ecological status of the Milford Haven Waterway and improved condition of the Pembrokeshire Marine SAC.