When your dam runs dry... dig a new dam

Here is our problem:

Plus we have a problem of a "scrape and fill" dam, which means it is very shallow - about 1.5 meters in a typical season.

Dams that are shallow evaporate quickly. A dam 3 meters deep will typically lose 60% over Summer while one 5 metres deep will lose 40%. So a 1.5 metre deep dam will lose...... everything!

So we have decided to fix the problem by pushing in the dam wall and digging a new dam.

This is fundamentally driven by the current dam being built over a stone reef which make digging down hard, and by the fact that the current wall is like a dike in Holland. It is unnecessarily high and aesthetically ugly.

The new dam will provide the following outcomes:

• Capacity of 4.5 Ml
• Deep
• Can swim in it during Summer
• Aesthetically integrated with the landscape
• Can be seen from the house as a feature

This approach was conceived by us but confirmed by both a local water expert and by the contractor who will dig the dam and move the earth.

Future posts will show the process.

Dams to Wetlands: Part 3 - Time to Plant

November and December are the best months to plant in and around the water of the dam.

As the dam water receeds, the space becomes accessible and new plantings have a chance to become established before being inundated by the Autumn rains.

The objective of the plantings is to:

1. Stabilise the soil around the dam
2. Create habitat for native wilflife, particularly  frogs
3. Become water purifiers
4. Improve the aesthetics of the space

We took the chance to put in about 70 plants as close to the water as possible. These included the River Bottle Brush (Callistemon sieberi) as we as various rushes (Juncus) species sourced from the local nursery and being of local provenance.

All these plants have the benefits of being fast-growing, while the Juncus is particularly easy to plant, not requiring staking or covering. The local Macropods also don't seem too interested when there is tastier grass to be found elsewhere.

The area we chose to plant was the gentle slope down the hill, which is basically a mud flat, full of silt and nutrients. This is in contrast to the dam-wall side, which is rocky and would be more difficult for the plants to establish.

The plantings on the mud-flat area should quickly spread and start to fill that space.

Rushes planted in the silt

Several Rush species

See the new plants to the right and below the dam

We'll check back in a few months and see how these are progressing.