Although it sounds like a place in a Winnie the Pooh book, the Slimbridge 5 Acre area currently takes runoff from wildfowl breeding pens and cattle sheds.
The work we are doing is for The Wildfowl & Wetlands Trust (WWT) and is a European funded project at Slimbridge, an internationally renowned nature reserve, important for wintering wildfowl.
The area is next to the offsite breeding pens and takes water from those pens plus from a winter housing area for cattle. The cows graze the fields on the reserve during the summer (an important part of the management of the land) and are kept inside in the winter. The breeding pens and the wintering cattle produce water that is high in nutrients and currently leaches straight into the ditch system at the centre.
The new wetland treatment area has a holding area for the runoff that will remove nitrates, phosphates and solids from the water, separating out the nutrient rich elements which can be spread on the fields as fertiliser.
Works have included the installation of two eel-friendly pumping stations; improving the ditch habitat for eels has been the impetus behind this European funded project.
The whole area is around one hectare of wetland habitat (2.5 acres). Once the new system is complete, it will range from deep water pools which will attract diving ducks such as shelduck, tufted duck and pintail, to reedbeds which will be home to breeding water rails and reed warblers and perhaps even wintering bitterns, through to marshes which will attract sedge warblers, feeding herons and little egrets – we might even get one or two cranes.
Apart from the wetland birds, the area will be very attractive to other wetland creatures – amphibians such as frogs, toads, newts and grass snakes which are in the area (grass snakes are semi aquatic so like swimming). There is a healthy population of water voles locally which will use the area.
Once the system is finished, the water will go into a large pool at the top, through a couple of parallel reedbeds, through some marshy vegetation, through some scrapes and swales (shallow, reed-lined ditches) before going back into the current ditch system. The water will be held higher than before which will allow WWT to control water levels on the reserve; flooding areas that remain too dry in the summer for example.
The result will be a system that is much cleaner than before, allows better water controls across the whole reserve and creates habitat for a variety of wetland species. It will also make it possible to use the nutrient rich runoff on the fields as fertiliser.