UK Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, LA1 4AP
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.
How to cite. Williamson, J., Evans, C., Spears, B., Pickard, A., Chapman, P. J., Feuchtmayr, H., Leith, F., and Monteith, D.: Will UK peatland restoration reduce dissolved organic matter concentrations in upland drinking water supplies?, Hydrol. Earth Syst. Sci. Discuss. [preprint], https://doi.org/10.5194/hess-2020-450, 2020.
Received: 01 Sep 2020 – Discussion started: 26 Nov 2020
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.
Water companies in the UK have found that drinking water from upland reservoirs is becoming...