South Para River Environmental flows

The and Natural Resources Management Board, SA Water and the Department for Water are collaborating on a trial to provide environmental flows to the South Para River. Environmental flows seek to mirror natural Para River because water is required for human seasonal flows, but in a modified way that takes consumption and industry, but we can plan to into account water security and flood protection. achieve the best possible environmental benefits Full flows cannot be returned to the South with the flows available.

GAWLER

FLOW DIRECTION

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PARA WIRRA RECREATION PARK

FLOW p DIRECTION N South Para Reservoir South Para River Barossa Diversion Weir to Gawler Barossa Diversion Weir

www.amlrnrm.sa.gov.au Environmental flows South Para River

The environmental flows will be delivered in four basic phases that mimic natural seasonal flows

No flow A dry phase where the river separates into a series of pools. Periods of no flow are important in recycling of nutients and creating food sources for aquatic animals. They also give native fish an advantage over introduced fish species.

Low flow These minimum flows are experienced over low rainfall months and are vital to maintaining the right water temperature and quality in pools, which provide an essential refuge for fish and other water-dependent life in dryer seasons.

Fresh flow These flows provide higher volumes of water and create more habitat for fish and allow them to travel between pools. The flows are essential to maintaining viable and widely distributed populations of fish.

Flush flow These high-volume, high-velocity flows scour sediment and vegetation that build up during lower flows. Over time sediment fills spaces between rocks, significantly reducing habitat for bugs, fish and other aquatic animals such as yabbies. Flush flows also allow fish to migrate both up and downstream and can provide important passage to the sea during breeding events.

120mm

Yabbie Mountain galaxias is a native fish found in the South Para River

Pool downstream of weir with poor quality, discoloured water Dry pool downstream of weir showing terrestrial vegetation resulting from reduced fresh flows encroaching into river bed resulting from reduced flows www.amlrnrm.sa.gov.au Environmental flows South Para River

The flows are part of a broader program that council areas, including the District Council of also includes the Torrens and Onkaparinga Rivers. Mallala, City of Playford, Light Regional Council, The trial commenced in December 2011 and Town of Gawler and Adelaide Hills Council. will run for three years. It will test the anticipated benefits of the environmental flows to aquatic The Barossa Diversion Weir diverts water for health predicted by scientific investigations treatment and transfer to metropolitan Adelaide. conducted over a number of years. Between the Weir and Tenefeate Creek, the river mainly flows through the Para Wirra Recreation The results will guide decision-making so Park. Downstream of Tenefeate Creek to ongoing environmental flows can optimise Gawler, the river flows through farmland and benefits to the rivers of the Mount Lofty Ranges. the surrounding vegetation has generally been cleared for agriculture. Native vegetation, where Why an environmental flows trial? present, consists predominantly of large remnant Water supply dams and diversion weirs are red gums and reeds and sedges that fringe the located along the South Para, Torrens and river. Onkaparinga Rivers for the purpose of storing and diverting water to Adelaide. The dams and During dry summers, the South Para River would weirs are an essential part of ensuring Adelaide have naturally stopped flowing, resulting in receives a reliable water supply. isolated pools along the river. Diversions from the river have extended the duration and frequency However, diverting water from rivers has of periods of no flow. It is estimated that the significantly interrupted the cycle of natural reservoir system has reduced flow periods below flows in our rivers and this has had a knock-on the South Para Reservoir by 90 per cent, with effect to the health of vegetation, fish and other no flows at all between January and July. organisms. In some cases, rivers experience Currently, the upper part of the reach only no flow up to 90% of the time, whereas prior receives large flows after the South Para to diversion they may have flowed all year round. Reservoir spills (about every five years). This has contributed to the local extinction of one species of fish with another three at risk While the South Para River between the of becoming extinct. Barossa Diversion Weir and Gawler retains good natural river form and vegetation, low flows South Para River trial reach and fresh flows could have significant aquatic ecosystem benefit. The section near Gawler has The trial reach on the South Para River extends a healthy and viable fish community, but other from the Barossa Diversion Weir downstream sections are lacking in native fish although the of the South Para Reservoir to Gawler at the potential for environmental flows to improve junction of the South and North Para Rivers. native fish habitat is high. This stretch of the river runs through several

1 Congolli is a native fish found in the South Para River

2 The Gambusia is a pest fish found in the South Para River and may be disadvantaged by natural flow conditions

3 Redfin are pests and voracious predators of native fish. Redfin are found in the South Para River

Photos courtesy of Dr D McNeil 1 and Dr M Hammer

2 3 www.amlrnrm.sa.gov.au Environmental flows South Para River

Environmental flow regime for the Measuring the trial South Para River A rapid and positive response to the flows can The flow regime for the South Para River has be expected for aquatic macroinvertebrates been determined through scientific investigations (bugs), while fish may take a number of years and would include annually: to respond fully. To make sure the environmental flows deliver intended benefits in the long term, n an extended no flow period from December the Board, SA Water and the Department for to May Water will be closely monitoring conditions in n two fresh flows, one in April and one in May the River to evaluate the success of the trial. (120 ML each over three days) The results will further be used to refine the n a base flow of 7.3 ML per day between June flows to optimise their environmental benefits. and November inclusive) The results will be made available to the n two flush flows, one in June and one in September (231 ML each over five days) community at key stages throughout the trial, with a full evaluation of the outcomes available n a fresh flow in November (72 ML over one day) following completion of the three year trial. n a total of 2015 ML over the year For further information visit Expected benefits for the www.amlrnrm.sa.gov.au/Water/ South Para River Surfacewater/Environmentalflows.aspx n Maintaining water quality in isolated pools conducive for aquatic life survival during the year n Maintaining aquatic habitat suitable for fish and other organisms n A self-sustaining population of Flathead ADELAIDE gudgeon with higher abundances than currently present, and regular breeding and Board office contact details recruitment Eastwood n An expanded Mountain galaxias distribution, with regular breeding and recruitment 205 Greenhill Road p N Eastwood SA 5063 n A reduced introduced Redfin population in the (08) 8273 9100 upper part of the reach [email protected] n No expansion in the distribution of introduced Eastern gambusia Gawler n A healthy macroinvertebrate (bug) community, 8 Adelaide Road which in turn underpins the health of the Gawler South SA 5118 aquatic ecosystem (08) 8523 7700 [email protected] n Healthy stands of native aquatic vegetation n Providing water for red gums in the lower Lobethal part of the trial reach 1 Adelaide Lobethal Road Lobethal SA 5241 (08) 8389 5900 [email protected]

Willunga 5 Aldinga Road Willunga SA 5172 Aerial photography/Cadastral data supplied by Customer Service Centre Client Services (08) 8550 3400 Department of Environment and Natural Resources [email protected] www.amlrnrm.sa.gov.au