Margaret River Wine Association | 1,835 followers on LinkedIn. Creating value for Margaret River growers and winemakers | The Margaret River Wine Association (MRWA) is the peak body for Margaret River grape growers and winemakers. It was established in the late 1970’s as the Margaret River Grape Growers & Winemakers Association and was incorporated in 1982. In 1996 the Association registered a geographic boundary for the region and the Margaret River became one of the first three wine regions in Australia to have its boundaries legally defined as a Geographical Indication (GI) by the Australian government.