This paper examines the spatial variation of salt lake morphology in the lower Yarra Yarra drainage system of Western Australia. Shape, size (length and area), orientation and density of 4500 salt lakes were measured. Two main morphological groups were distinguished: small (< 10ha), elliptical to circular playas with a NNW-SSE orientation; and large (> 30ha), elongated playas. Intra-system variability in morphologic characteristics was notable. Regional patterns in lake size, shape and density distribution were markedly different between the west and east sides of the system. The boundary between the two sides coincides approximately with rainfall distribution.The Morawa sub-division in the west of the region was morphologically different from the remainder of the lower lacustrine system in that it had a predominance of small, elliptical playas and lacked a major playa. It was postulated that lake segmentation processes have been enhanced in this part of the system through a combination of local climate variation, the near-parallel orientation of the thalweg of the drainage system axis relative to prevailing winds, with possible topographical relief and geological influences. (c) 2005 Elsevier Ltd. All rights reserved.