The British government and other European Union countries brought in a revised Bathing Waters Directive last year with more stringent standards for the quality of our recreational waters including bathing beaches, inland lakes and rivers. Together with the new European Union Water Framework Directive which must be enforced from 2015, experts expect that the quality of bathing, surface and ground water will become much more of an important issue in the near future.
"We already see some designated bathing sites failing the standards," says Dr Chris Hodgson from the Institute of Grassland and Environmental Research (IGER) at North Wyke Research Station near Okehampton in Devon. "Partly this can be attributed to low level but widespread sources of contaminated water run-off from agricultural land".
"This run-off contains harmful and disease-causing bacteria, and typically follows the recycling of livestock manures such as slurry spreading on fields, and from uncontained runoff from farmyards, or from direct faecal deposition by sheep, cattle and other animals as they graze" says Dr Hodgson.
With funding from the Rural Economy and Land Use programme (RELU), the scientists from IGER, Exeter and Lancaster universities have developed a method, called an expert-weighted risk tool, to rank fields and farmyards for the likelihood of indicator bacteria such as E. coli, which they know are only found in faeces and slurries, being transferred to rivers and streams at different times of the year.
Their method was tested on two working farms, and in one the farmyard was identified as having the greatest risk of the bacteria transferring to a stream, while on the second farm the fields posed the greatest risk.
"By checking the concentrations of the indicator bacteria in streams and ditches around the farms we gathered the physical evidence that proved that our expert-weighted risk tool actually works", says Dr Hodgson.
Because the new system calculates relative spatial risk, rather than being a quantitative predictive model which suggests specifically how much contamination will occur, the developers hope it will assist farmers and land owners to prioritise land that is most 'risky' in terms of contributing bacterial contamination to watercourses. This in turn will help focus clean-up and prevention efforts where they are likely to be most effective for improving water quality.
Overall the new tool should help to make recreational waters safer to use, increasing the confidence of tourists, local people and visitors, reducing the cases of illness from contaminated water, and helping to maintain rural communities.