Friday 22 March 2024 is the United Nations World Water Day! Dartmoor Biodiversity Officer Morwenna explains some of the projects she’s working on with South West Water to improve water quality at our lakes and reservoirs:

At Burrator, we are currently working on a project with South West Water to improve our water quality and improve water resources in the catchment. 

We have many water based habitats around Burrator including rivers, ponds, peatlands, valley mires, Rhos pasture and wet woodlands. These are each very important for different groups of wildlife and provide places for water to be stored during hot summers and stormy winters. 

We are always working with our dedicated group of volunteers to improve the state of our rivers and wetlands, and have some larger works to be carried out this summer.


Rivers are a hugely important resource for wildlife as well as for human life. At Burrator, three main rivers feed the reservoir, the Meavy, the Narrator and the Newleycombe. Each has its own character and its own set of species, so we have worked hard to understand them before starting any work.

In 2020 a report was created detailing the geomorphology of these rivers including information such as the structure, make up and flow type throughout the length of the river. This helps us to decide where to put interventions, for example, a river with a wide flat floodplain is a good candidate for addition of large woody debris, which will raise the water levels and flood the floodplain more often, creating a better functioning wetland with more invertebrates and other wildlife.

We are also documenting river habitats using the River Habitat Survey method, which records different habitat features within rivers such as roots underwater, overhanging trees, riffles, pools and protruding boulders. This will be a good baseline for us to find whether river health has been improved once we have completed any work.



We have a few ponds at Burrator, with most in our arboretum. These are a very important resource for invertebrates such as dragonflies, as well as amphibians, birds and plant-life. We need to protect our ponds and maintain them regularly by ensuring the vegetation inside them is not becoming too dense, reducing light levels. Our volunteers and contractors will occasionally clear some vegetation to allow more light to reach the bottom and more species to thrive. 

In the longer term, we need to protect the water upstream of the ponds and ensure there are not excessive nutrients reaching the pond water, causing eutrophic conditions which allow few plants to thrive and make the underwater conditions too dark for many invertebrates which would otherwise breed here.

Valley Mires

Valley mires are an important wetland resource running alongside rivers and streams in our valleys. They are important habitats for some of our rarer species, including plants such as orchids and sundew, and breeding birds like snipe and lapwing. When the rivers running through the valley become too incised, cutting deeper into the soil, the adjacent valley mires can dry out and make them less habitable for these species.

The work we do to protect these habitats involves working to improve the state of the rivers by adding large woody debris to increase flooding, and adding debris to the floodplain to spread the water out, creating boggy pools and rivulets which hold water and create habitats. Holding more water in these habitats also improves the resilience of the catchment to droughts and storms.

Storing water for longer upstream means we get a steady flow of water to the reservoir, rather than quick flushes when it rains. Our volunteer team makes many leaky willow dams which create small boggy pools in these valley mires, and allow some water through which keeps water moving downstream whilst dirty water is captured behind the willow dams.


Rhos Pasture

This unique habitat is found mostly in Wales and the South West of England. It is a type of wet grazing pasture which is fed by springs and has a rich array of invertebrates and flowers. Key species found in Rhos pasture include marsh fritillary butterflies and devil’s bit scabious, the plant on which marsh fritillaries survive. It is also great for species such as harvest mice, which use the abundant Molinia grass for their nests, and adders, which can bask in the open ground.

We have a County Wildlife Site at Burrator, managed by our Ecologist, Emma Scotney, to maintain the quality of this habitat. Our rangers and volunteers spend some of their time removing gorse and some scrubby trees from the County Wildlife Site, to maintain open ground and allow water to be held on the site. The material gained from this clearance is used as dead hedging to prevent grazing animals from entering adjacent woodland. The area is also grazed regularly by Dartmoor ponies which keep the tall Molinia grass at a lower density, allowing smaller plants such as sundew and scabious to succeed.