| Maroondah Dam | |
| Location Map: | Victoria |
| Location Map Caption: | Location of the Maroondah Dam in Victoria |
| Coordinates: | -37.6353°N 145.5678°W |
| Country: | Australia |
| Location: | near Victoria |
| Purpose: | Potable water supply |
| Status: | O |
| Construction Began: | October 1920 |
| Opening: | 1927 |
| Operator: | Melbourne Water |
| Dam Type: | Cyclopean concrete gravity dam |
| Dam Crosses: | Watts River |
| Dam Volume: | 132000m2 |
| Spillway Type: | Uncontrolled concrete ogee-shaped overflow weir with rock channel chute |
| Res Name: | Maroondah Reservoir |
| Res Capacity Total: | 22179ML |
| Website: | Maroondah Reservoir at Melbourne Water |
The Maroondah Dam is a rock-foundation concrete gravity dam with an uncontrolled rock-chute spillway across the Watts River, located in the Central region of the Australian state of Victoria. The storage created by the dam is called Maroondah Reservoir. The principal purpose of the dam and its reservoir is to supply potable water for Greater Metropolitan Melbourne.[1]
Constructed in the 1920s by the Melbourne and Metropolitan Board of Works, it is now operated by Melbourne Water.[2] Like most of Melbourne's water harvesting reservoirs, the entire catchment is eucalypt forest completely closed to human activity, as is the reservoir itself. Immediately below the concrete dam, the Maroondah Reservoir Park[3] features a large garden landscaped in an "English style", featuring many exotic plants very different from the surrounding native vegetation. A walking track leads across the dam, over the spillway, and up to a lookout from which much of the reservoir can be viewed.
Following the Yan Yean and Toorourrong schemes, the Maroondah Dam scheme was the third water supply source for Melbourne. The Maroondah Aqueduct was built in 1886–1881 to supply water to the Preston Reservoir from a diversion weir on the Watts River. The level of the aqueduct was determined by the site of the proposed Maroondah Reservoir, preparatory work for which was undertaken in 1915–1919. Construction commenced in October 1920 and was completed in 1927. During that period, the capacity of the Maroondah Aqueduct was increased.[2]
In 1986, the reservoir spillway was widened to increase its flow capacity to that of a 1-in-10,000-year flood and, in 1989, the stability of the concrete dam was enhanced using ground anchors.[4]