Water

Low water not so bad

By Country News

About 200 carp have died in Richardson’s Lagoon near Echuca as a result of expected low water levels.

North Central Catchment Management Authority is currently monitoring the wetland, which it says supports a high diversity of waterbirds and woodland birds.

The lagoon can receive water from the Murray River during very high natural flooding, but such occasions are rare, as it was disconnected from the river by levees built to regulate the system.

As a result, water for the environment is the only reliable way Richardson’s Lagoon receives flows.

North Central CMA manager Trent Gibson said the lagoon was in a drying phase, an important part of ensuring its long-term health.

‘‘Given Australia’s harsh climate, it’s understandable to think low water levels are a bad thing,” Mr Gibson said.

‘‘In many cases, including at Richardson’s Lagoon at the moment, the exact opposite is true.

‘‘Fluctuating water levels are great for birds and plants.

‘‘Receding water gives opportunities for wading waterbirds such as herons, plovers and stilts to stalk the shallows for fish and insects.

‘‘Surrounding trees also need to have dry feet from time to time, to help with seed germination and stop them from drowning.

‘‘Wetlands across the region are full of dead eucalypts that have died because of historically high permanent water levels.’’

Mr Gibson said low water levels also helped mitigate against blue-green algae outbreaks.

‘‘The lagoon has a long history of high-nutrient concentrations that have contributed to blue-green algae blooms,’’ he said.

‘‘To mitigate against further algal blooms and provide the best habitat available for the significant bird population, it’s important the water level in the lagoon fluctuates, with periods of both wetting and drying.

‘‘Complete drying exposes the bottom of the lagoon to the air, allowing the algae to break down totally and turn into compost which is great for the soil.

‘‘Complete drying can mitigate the risk of future algae blooms at Richardson’s Lagoon and allow many native wetland plants to complete their life cycles.’’