In 1953 a property known as ‘Exmoor’ in the Berkshire Valley was supported by the government to secure water storage by building — what would be at the time — the state’s biggest farm dam.
The present owners of this well-built dam, the Gardiner family, were excited to see this massive store overflow this winter. It is thought to be the first time this has happened since the 1999 Moora floods, possibly even longer as the property has changed hands over the years and records have gone astray.
Owner Daniel Gardiner was proud to show where the excess water from recent rains flowed over the dam wall, demonstrating that the old earthwork held up to the flow with only minor erosion. This is thanks to the original spillway doing the job it was designed for, releasing the majority of the excess safely. Daniel said, “I’ll have to get in there and clean it out though, because it obviously couldn’t keep up with the amount of rainwater flowing in from the surrounding 800-acre catchment.”
A big and sudden dump of rain last April gave the dam a boost with the surrounds being so dry that almost everything that hit the earth ran into the dam very quickly, and this winter’s rainfall has topped it off nicely. 6,000,000 gallons of stored water is a big number, and in metric terms it is even bigger – 27 million litres, in today’s terms. It was estimated that this would simulate a 12-inch annual rainfall in the catchment. This all sits behind an almost 10 m high wall that was constructed from clay hewn out of the slopes next to the dam site on the property, and was shored up on the water side with large local rocks. Scars from these earthworks in the paddocks near the dam are still visible despite the many decades of activities on the property.
Before the dam was built by Henry Kelsall, there were small permanent rockpools at the top of the small valley, so it was a simple theory that catching the trickle from the spring as well as runoff from the surrounds into this natural bowl would work well. Once complete, this dam was able to supply the property with water security for decades, carrying it through long hot summers and periods of lower rainfall. It is no longer the main supply for the farm as they have since found a bore that gives even more reliable water thanks to improvements in technology.
Still holding strongly after 70 years, this marvellous piece of ingenuity and engineering provides a stunning visual representation of why farmers throughout the region are lapping up two good rainfall seasons in a row.
