Ham Wall is an English wetland National Nature Reserve (NNR) 4 kilometres (2.5 mi) west of Glastonbury on the Somerset Levels. It is managed by the Royal Society for the Protection of Birds (RSPB). Since the last Ice Age, decomposing plants in the marshes of the Brue valley in Somerset have accumulated as deep layers of peat that were commercially exploited on a large scale in the twentieth century. Consumer demand eventually declined, and in 1994 the landowners, Fisons, gave their old workings to what is now Natural England, who passed the management of the 260 hectares (640 acres) Ham Wall section to the RSPB.
The Ham Wall reserve was constructed originally to provide reed bed habitat for the Eurasian bittern, which at the time was at a very low population level in the UK. The site is divided into several sections with independently controllable water levels, and machinery and cattle are used to maintain the quality of the reed beds. There are important breeding populations of wetland birds including the rare little bittern and great white egret, and the area hosts several other uncommon animals and plants. The RSPB works with other organisations as part of the Avalon Marshes Partnership to coordinate conservation issues across the Somerset Levels.
The reserve is open year-round, and has nature trails, hides and viewing points. It lies within the Somerset Levels NNR and the Somerset Levels and Moors' Ramsar and Special Area of Conservation site. Potential future threats may result from increasing unpredictability in the UK climate, leading to heavy summer rains and extensive flooding. Sea level rise will make the drainage of the Levels more difficult, and current water pumping facilities may become inadequate.