Page 58 - VEWH Seasonal Watering Plan 2020-21
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 2.2. Latrobe system
Scenario planning
Table 2.2.4 outlines the potential environmental watering and expected water use under a range of planning scenarios.
The planned approach in 2020–21 at the lower Latrobe wetlands is to mimic natural flows in the system by controlling flow through the regulators when water levels and water quality in the Latrobe River allow. Following extended drying in 2018–19 and 2019–20, actively- managed drying is not prioritised under any scenario, although this will likely occur naturally at all wetlands under drought, particularly as reduced flow in the Latrobe River leads to high salinity that may exceed recommended wetland tolerances.
The preferred watering regime for Sale Common involves:
• partially filling the wetland in winter and providing top-ups as needed to maintain water levels above 0.3 m AHD throughout the year to support wetland plant communities and habitat for frogs, turtles and waterbirds, and
• filling the wetland for at least two months from late winter or early spring to connect the wetland to the Latrobe River, stimulate the growth and recruitment of plant communities at the outer margins of the wetland and encourage waterbird breeding by providing appropriate nesting habitat.
Further top-ups may be delivered in response to a significant waterbird breeding event, if needed to protect the nests from ground-based predators and to maintain adequate food resources for nesting adults and chicks. Maintaining a target water level of 0.3 m AHD will wet about half of Sale Common, and it is considered important for ecological communities that experienced near-complete drying in 2018–19 and 2019–20. These watering actions are planned to be delivered under all scenarios, where possible.
The preferred watering regime for Dowd Morass involves:
• partially filling the wetland in autumn to maintain wetland plant communities and provide habitat and food resources for waterbirds, frogs and turtles
• filling the wetland in winter and spring to trigger waterbird breeding and improve the condition of streamside vegetation communities
• maintaining water at suitable levels through spring and summer to maintain habitat for aquatic plants and animals.
Additional water may be delivered to Dowd Morass at any time of year as needed and as water levels in the Latrobe River allow, to manage high salinity (caused by king tides from Lake Wellington) or to help waterbirds successfully fledge. The preferred water regime is likely to be delivered under dry, average and wet scenarios, but flow in the Latrobe River may not be high enough to allow Dowd Morass to fill under a drought scenario. Waterbird breeding is also a lower priority under a drought scenario, because there are unlikely to be sufficient resources in the surrounding landscape to support chicks and juveniles.
The preferred water regime for Heart Morass involves:
• maintaining water levels above -0.3 m AHD year round to prevent exposing acid sulfate soils
• partially filling the wetland from winter through to
early summer to support wetland plant communities, maintain habitat and food resources for frogs, turtles and waterbirds, and to provide breeding opportunities for waterbirds
• briefly filling the wetland to allow a partial flush during a winter/spring high flow event in the Latrobe River to remove accumulated salt and sulphides.
Additional water may be delivered to Heart Morass at any time of year as needed and as water levels in the Latrobe River allow, to control water quality — that is, to respond
to a low pH or a high-salinity event — or to help waterbirds successfully fledge. Water levels in the Latrobe River are not expected to be high enough to support a partial flush of Heart Morass under a drought scenario, and under a wet scenario the partial flush is likely to be replaced by a natural flood that will flush the whole wetland.
        56 | Victorian Environmental Water Holder | Seasonal Watering Plan 2020–21
 













































































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