How repairing peat could prevent Glasgow's tap water turning brown
BBCHundreds of hectares of peatland is being restored in a project which aims to prevent Glasgow's tap water turning brown during extreme rain.
Loch Katrine, in the heart of Loch Lomond and the Trossachs National Park, supplies water to 1.3 million people in and around Scotland's largest city.
But the peat in the hills surrounding the loch has degraded, which allows soil and brown particles from plants to flow into the water.
The heavier rainfall which comes with a warmer climate is expected to increase this organic run-off, which is tricky and expensive to remove at the treatment works - and without intervention will lead to water turning brown during major storms.
If it is not treated successfully, it poses health risks from bacteria and the microscopic cryptosporidium parasite.
The decaying plant materials can also affect the taste and smell of the water.
The restoration work is part of a long-term land management plan for the hills around the eight-mile-long (13km) fresh water loch.
The project, which will also see the creation of one of Europe's largest new woodlands, is expected to capture a million tonnes of carbon over 60 years and increase the amount of biodiversity on the site.
Loch Katrine is the source of most of Glasgow's drinking water, which is carried along Victorian aqueducts to treatment works at Milngavie.
The estate containing the water catchment is owned by Scottish Water and is managed by Forestry and Land Scotland.
It covers an area of almost 10,000 hectares, about 400 hectares of which is in the process of being restored - around the same size as 400 Murrayfield stadiums.
A good quality peatland is like a wet bog with a high water table and an abundance of aquatic life.
Those near Loch Katrine were initially degraded by overgrazing, which was then made worse by the wind and rain.
This leaves hags - steep banks of exposed peat where fresh vegetation is unable to grow.
More intense rainfall has led to an increase in organic run-off from the peat, which means that without intervention the water will turn brown during heavy storms.
Elise Cartmell, Scottish Water's general manager for net-zero, said: "This natural organic matter is really complex to treat and we're having to use energy and chemicals.
"So, as part of our net-zero ambitions, we're obviously trying to reduce, as much as possible, these inputs."
Elise said the increased run-off was not unique to Loch Katrine with water catchments across Scotland "on life support" and needing to be repaired.
Preventing overgrazing, removing previously engineered draining systems and stopping erosion are key techniques to allow the catchments to repair and recover.
Poor quality peatlands release huge amounts of planet warming carbon dioxide into the atmosphere and restoring them is vital to tackling climate change.
Alongside the restoration, advanced monitoring technologies have been installed on the peatland and in Loch Katrine to track the water quality.
Radiometer sensors have been attached to the Sir Walter Scott steamer - which measure light reflection from the water's surface - while a newly installed static buoy takes readings of temperature, conductivity and concentrations of sediment.
They provide real-time information every 15 minutes via satellite.
Prof Peter Hunter, an environmental scientist at the University of Stirling, says the readings provide very helpful research data.
He added: "It tells us something about land management in the catchment around Loch Katrine and the impact of some of the nature-based solutions that Scottish Water are implementing but it's also very helpful to verify some of the data we receive from space."