26 Nov 2020
26 Nov 2020
Status: this discussion paper is a preprint. It has been under review for the journal Hydrology and Earth System Sciences (HESS). The manuscript was not accepted for further review after discussion.

Will UK peatland restoration reduce dissolved organic matter concentrations in upland drinking water supplies?

Jennifer Williamson1, Christopher Evans1, Bryan Spears2, Amy Pickard2, Pippa J. Chapman3, Heidrun Feuchtmayr4, Fraser Leith5, and Don Monteith4 Jennifer Williamson et al.
  • 1UK Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd, LL57 2UW
  • 2UK Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB
  • 3School of Geography, Faculty of Environment, University of Leeds, Leeds, LS2 9JT
  • 4UK Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, LA1 4AP
  • 5Scottish Water, 6 Castle Drive, Dunfermline, KY11 8GG

Abstract. Rising dissolved organic matter (DOM) concentrations, and associated increases in water colour, have posed a potential problem for the UK water industry since the phenomenon was first reported in the early 1990s. Elevated DOM concentrations in raw water are of particular concern in upland catchments dominated by organic soils where DOM production tends to be highest. In recent years, water companies have considered the capacity for catchment interventions to improve raw water quality at source, relieving the need for costly and complex engineering solutions in treatment works, but there is considerable uncertainty around the effectiveness of these measures. One of the primary evidence gaps is the extent to which catchment management is capable of influencing DOM concentrations at the point of abstraction, field studies rarely extending beyond sub-catchment or stream scale. Our review of the published evidence suggests that catchment management could make a contribution to mitigating recent DOM increases in some circumstances, particularly where plantation forestry has been grown on peat, and where control of nutrients in runoff could reduce in-reservoir DOM production. Evidence for the efficacy of most other measures that target reductions in DOM loading for catchment to reservoir remains insufficient to support wider scale application. Collectively, these measures have the potential to reduce DOM concentrations in drinking water reservoirs but they must be selected on a site-specific basis, where the scale, effect size and duration of the catchment intervention are considered in relation to both the treatment capacity of the works and future projected DOM trends.

Jennifer Williamson et al.

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Jennifer Williamson et al.

Jennifer Williamson et al.


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Short summary
Water companies in the UK have found that drinking water from upland reservoirs is becoming browner. This is costly to treat and if the dissolved organic matter that causes the colour isn't removed potentially harmful chemicals could be produced. Land management around reservoirs has been suggested as a way to reduce water colour. We reviewed the available literature to assess whether this would work. There is limited evidence available to date, although forestry appears to increase colour.