Introduction
In Scotland, many of our drinking water catchments contain deep and shallow peat soils. When large areas of these soils are present it can result in high colour and organic carbon levels in water supplying our Water Treatment Works (WTW). This affects the water treatment process, making it more costly and energy intensive to treat. Through our routine monitoring data we have identified a number of sites where the level of organic carbon in the source water is increasing. There are a number of reasons why this increase may be occurring. It could be due to factors we have little control over, such as climate change or changes in atmospheric pollution. However, it could also be related to land management activities, such as installing drainage ditches, over grazing, afforestation, heather burning, or construction work.
If land management activities are having an impact then we would like to work with land managers to restore organic soils to their natural condition. Research has shown that restoring these soils can be an effective management strategy for reducing organic carbon and water discolouration. This will help improve source water quality and reduce water treatment costs.
Approach and methodology
We have set up a project to survey and monitor a number of catchments that provide source water to some of our WTW. This work includes:
* Desk top assessments, gathering information about the catchment and examining water quality data
* Catchment surveys by Scottish Water's Sustainable Land Management (SLM) Team, to identify any areas of concern and possible intervention methods
* Identifying sites for baseline monitoring
* Identifying sites suitable for detailed surveys by peatland ecologists
* Identifying the land managers within the area
Five sites have been selected for baseline sub-catchment monitoring. This monitoring will commence in autumn 2014 and continue until March 2018. Some sites are not suitable for routine monitoring due to their location. For these sites we will undertake a vegetation survey to act as a baseline and to help identify intervention methods.
The type of intervention that takes place will depend on the catchment but could include grip blocking, re-profiling and re-vegetating areas of bare peat.
Results
We are working closely with various organisations including Scottish Natural Heritage (SNH), Scottish Environment Protection Agency and the Forestry Commission Scotland to help improve source water quality in our catchments. To assist with this some of the SLM team have spent time working in each organisation, enabling a valuable transfer of knowledge.
The time spent with SNH focused specifically on peatland restoration. This has helped the team learn how to recognise when peatland is deteriorating, what monitoring needs to take place and which restoration techniques would be appropriate.
Conclusions
Many of our drinking water catchments contain peat soils. When large areas of these soils are present it can result in high colour and organic carbon levels in water supplying our water treatment works. This affects the water treatment process, making it more costly and energy intensive to treat. We have set up a project to survey and monitor a number of catchments where the level of organic carbon is increasing. This will help us identify appropriate mitigation measures to improve source water quality.