Emerging landscapes

Creating an open body of water has been transformative for my garden. Within months of installing a pond, frogs, dragonflies, birds and water boatmen all turned-up to use the precious resource. Here, I share my strategies for creating a wildlife friendly pond, without blowing the water budget or creating a mozzie problem.

In the scheme of my household water budget, a pond is a low water-use, high value entity. My small pond uses about the same amount of water as a crop of tomatoes in a garden bed of similar size: about 9-10 L per day at the height of Castlemaine summer (the surface area of the pond is1.5 square meters [1]) My family all agree that this a worthwhile use of our household water budget; roughly equivalent to 1.5 flushes of our toilet per day.

The amount of water lost from my pond is reduced by planting trees and shrubs nearby. The dappled shade from these plantings keeps the pond cool in summer and reduces water evaporation. The trees and shrubs also provide valuable habitat where birds feel safe and protected from predators, allowing them to swoop down for a drink or a bath and then back to the safety of a canopy.

My pond is filled with native water plants that provide summer greenery, help to purify the water and build our pond ecosystem. While aquatic plants do lose water to the atmosphere through a process known as evapotranspiration, their effect on a garden’s water-budget is roughly neutral, because their water-use is offset by their shading and cooling effect (ie the shade reduces water evaporation from the pond).

My pond was simple and inexpensive to install. It just required some muscle power to dig the hole, a sheet of pond-grade plastic, a layer of sand under the plastic to prevent sharp stones perforating and a ring of recycled bricks around the edge to finish it off and hide the plastic. The pond is circular and has two levels that support a varied and resilient pond ecosystem. A shallow-zone (25 cm deep) around the perimeter is planted with Water Milfoil and Water Plantain, which create a bright green border. A deep zone in the centre of the pond (50-70 cm deep) has floating aquatic plants such as Nardoo, Water Plantain and Marshwort, which are rooted in pots that sit on the pond floor. The deep zone is where tadpoles shelter from predatory birds and extreme hot or cold temperatures.

To prevent the proliferation of mosquito larva in the pond I released two native Murry Rainbow Fish, bought from a local pet shop These shy fish eat the mosquito larvae but leave the frogs eggs alone, so they are a great complement to the thriving pond ecosystem. Within a few months of planting out the pond and releasing the fish, my family were stunned when we found a frog egg mass amongst the leaves of the milfoil. Three years later we enjoy clear water (without a pump or fountain), abundant water life and there’s not a wriggler (mosquito larvae) to be seen.

Article by Cassia Read. First published in ‘The Watering Can,’ Western Water’s garden e-news, Summer, 2018

[1] These estimates are based on how much water I use to fill the pond each week and also calculations of water evaporation/evapotranspiration rates, using data from the Bureau of Meteorology.