As part of the Healthy Waterways Strategy 2018 (HWS2018) the Melbourne Water operating region was split into a series of sub-regions. This includes 5 catchments, and 69 sub-catchments. The boundaries of each region generally follow catchment boundaries. There are two separate spatial scales:- Catchments (5 regions: Werribee, Maribyrnong, Yarra, Dandenong, Westernport) and Sub-catchments (69 polygons). This dataset is an update to the Regional River Health Strategy (RRHS) Management Units layer created in 2008. Primary purpose of this data is for reporting of targets, performance objectives, conditions, values etc. relating to the Healthy Waterways Strategy.The sub-catchments in this dataset are an update of the "management units" developed for the Regional River Health Strategy in 2008. This dataset was created by merging sub-catchments from the University of Melbourne sub-catchments layer, commonly referred to as the DCI layer (where DCI refers to Directly Connected Imperviousness). The catchment polygons in this layer are similar to, but not exactly the same as those in the DCI layer currently used internally at Melbourne Water - The internally used layer has 15,901 polygon catchments, whilst the layer used to create this dataset has 16,346 polygon catchments. The Melbourne Water internal dataset will shortly be updated to align.NOTE: Whilst every effort has been taken in collecting, validating and providing the attached data, Melbourne Water Corporation makes no representations or guarantees as to the accuracy or completeness of this data. Any person or group that uses this data does so at its own risk and should make their own assessment and investigations as to the suitability and/or application of the data. Melbourne Water Corporation shall not be liable in any way to any person or group for loss of any kind including damages, costs, interest, loss of profits or special loss or damage, arising from any use, error, inaccuracy, incompleteness or other defect in this data.