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Monitoring environmental watering at Hattah Lakes

  Monitoring environmental watering at Hattah Lakes
 
Large pumping structure delivering flows to Hattah Lakes 2013–14

Full Title

Response of fish and vegetation communities to the operation of TLM environmental regulators at Hattah Lakes

Contact Person

Mark Henderson

Funding Body

Mallee Catchment Management Authority

Duration

Monitoring occurred prior to inundation (2012–13), during inundation (2013–14) and three months following inundation (April 2014). Evaluation and reporting followed in 2014.

Collaborators

Summary

MDFRC designed an intervention monitoring program to capture the effects of environmental flows on fish, wetland vegetation, floodplain understorey and trees at Hattah Lakes. Intervention monitoring investigates the links between management actions and ecological responses in order to improve site management.

Hattah Lakes is one of six icon sites identified as ecologically significant under The Living Murray (TLM) program. Located within the Hattah-Kulkyne National Park in Victoria’s northwest, Hattah Lakes contains numerous freshwater lakes, 12 of which are Ramsar-listed. The lakes are connected by a series of floodplain channels which become inundated when the Murray River overflows its banks during periods of high flow. River regulation and the extraction of water for agriculture, industry and urban use has significantly altered the frequency, magnitude and duration of river flows. This has subsequently affected the flow regimes of associated wetlands, waterways and the floodplain. Hattah Lakes has significance in protecting endangered species of flora and fauna in Australia and provides refuge for a range of endemic biota including fish, birds and vegetation, many of which are sensitive to flooding regimes.

TLM is a large-scale restoration project that attempts to ameliorate the negative effects of river regulation by returning water to the environment. The aim of these environmental watering events is to help restore the hydrological balance which has been altered from natural flows. Significant investment has been made in infrastructure, including the construction of a pumping station, three regulators and stop banks to help deliver environmental flows to the Hattah Lakes.

During this initial pumping event, the pumping station delivered 60 904 ML of water to the Hattah Lakes (spring and summer 2013–14). The purpose of these flows was to inundate long-dry parts of the floodplain that were last flooded in 1993–94 (~20 years ago).

Intervention monitoring examines the links between managed environmental watering and ecological outcomes. The purpose of this intervention monitoring program was to investigate the effects of these flows on fish, wetland vegetation, floodplain vegetation and trees. The project investigated composition of the fish community pumped into the receiving waters of Chalka Creek, comparing it with the (source) Murray River fish community. Vegetation and tree monitoring occurred prior to inundation (summer 2012–13), during inundation (summer 2013–14) and three months following inundation (April 2014). This program is important to improve our understanding of how hydrology affects the maintenance of fish and vegetation communities in order to improve icon site management, both at Hattah Lakes and more broadly.

For more info on Hattah Lakes and/or TLM refer to featured project: condition monitoring at Hattah Lakes

Floodplain at Hattah Lakes. From left to right; before (2012–13), during (2013–14) and following inundation (April 2014).