Thorley Wash, formerly known as Thorley Flood Pound, is a 17.3-hectare (42.7 acres) biological Site of Special Scientific Interest in the Roding Valley, near Bishop’s Stortford in Hertfordshire.^[1] It was originally a flood pound for the Stort Navigation, but is now a nature reserve managed by the Herts and Middlesex Wildlife Trust.^[2][a]A pound is the stretch of water between two locks.^[3]

The site contains a range of habitats associated with a fluctuating water table, including tall wash grassland, baserich marsh and ill-drained permanent grassland.^[1] Since 2023 water buffalo have been used to graze the waterlogged and marshy grasslands, which has increased the site’s biodiversity.^[4]

Flora and fauna

Flora

The wide variety of plant species found in Thorley Wash include Reed Sweet-grass (Glyceria maxima), Meadowsweet (Filipendula ulmaria), Marsh marigold (Caltha palustris), Ragged Robin (Lychnis floscuculi) and Fen Bedstraw (Galium uliginosum).^[1] The Marsh marigold in particular seems to have thrived since the introduction of the water buffalo.^[4]

Fauna

The site provides a habitat for Snipe (Gallinago gallinago), Water Rail (Rallus aquaticus), wildfowl and other ground-nesting birds. Insects include dragonflies and damselflies such as the Banded demoiselle (Calopteryx splendens) and Broad-bodied chaser (Libellula depressa).^[1] Water voles (Arvicola amphibius) were successfully reintroduced to Thorley Wash in 2015.^[5]