Appendix 2: Clean and plentiful water

Upsides

i) The blocking of drainage ditches by grouse moor owners and managers is likely to be improving water quality by preventing the further release of sulphur, nitrate, ammonia and metals that had occurred due to the lowering of water tables associated with peat erosion or drainage¹⁹.

ii) Water from functioning peatlands is high quality because vegetation, especially mosses and lichens, captures and retains a range of atmospheric pollutants¹⁷. The ONS estimates the annual value of UK drinking water from peatlands at £888 million and the asset value at £18.366 billion in 2016²⁰. These ONS estimates are based on the costs relating to both water supply and water treatment.

iii) By dividing these figures by the area of peatland in the UK (estimated by ONS as 2,962,622 hectares) and then multiplying by the area of English peatlands under grouse moor management (282,000 hectares⁸), we estimate that the annual value of English GMM to drinking water provision is c.£84.5 million and asset value c.£1.75 billion.

iv) Vegetation cover represents a key control on storm runoff in peatland catchments²¹, and therefore the quantity and quality of the water downstream.

Downsides

v) Degraded peatlands comprise areas of exposed bare peat, which can adversely affect the quality of drinking water through increases in dissolved organic carbon, which causes brown peaty water²², acidity and concentrations of suspended sediments or fine particulate organic matter and metals¹⁹.

vi) Concerns have been expressed that disease control on grouse moors (notably flubendazole in medicated grit) could impact on water quality. Review work in Scotland suggested that while the risk was low, concentrations may be underestimated where there is poor practice and that uncertainties required further investigation²³.

Challenges

vii) Restoring degraded peatland through re-vegetation and grip blocking may affect the regulation of water supply. Rewetting and saturation with water is likely to lead peatlands to produce ‘flashy’ run-off¹⁷ reduced water quality²⁴ through increased over-land flow. See also Flood mitigation (Appendix 4 - Reducing risk of harm from environmental hazards).

viii) The IUCN²⁵ has noted that further research is required on the impact of climate change on water quality. However an increase in ‘intense’ rainfall events²⁶ and changes in snow-lie are likely to influence water quality¹⁷ (notably particulate carbon losses via runoff) while drought and rewetting sequences increasing Dissolved Organic Carbon (DOC) losses²⁷. Rainfall is likely to be more important than temperature in shaping long-term changes in runoff²⁸.

ix) Peatland instability due to climatic and land management changes raises the risk of release of some heavy metals and Persistent Organic Compounds into river systems¹⁷ thereby affecting water quality.

x) Vegetative change in peatlands may occur due to climate change, land management and nitrogen deposition²⁹and this can affect DOC losses³⁰.

Opportunity

xi) The impacts that controlled burning (and interactions with drainage and grazing) may have on water quality are still not well understood.  Study results differ depending on timescale since burning event and spatial scale. Commonly cited studies of burning and water colour have highly divergent views^31-33.