Snowy River increased flows

In determining how to use the environmental water in the Snowy River, the three governments agreed that the primary ecological objective would be achieved by storing and then releasing sufficient volumes to provide annual flushing flows. These high flows facilitate the improvement in the physical condition of the in-stream habitat by scouring and transporting sediment (i.e. primarily, sand, silt and clay). This primary ecological objective was identified as a high priority for the environment during the Snowy Water Inquiry. These high flows are important to improve river health. It is expected that as the river physically responds over time to the higher flows, the focus of the recovery process will transition to meet other secondary ecological objectives.

2017–2018 Water year

A revised operational target of 218.5 GL is to be released to the Snowy River during 2017–18 from Jindabyne Dam, which includes a base passing flow of 8.5 GL. An additional 0.5 GL of base passing flow will be delivered from the Mowamba Weir.

Additional to the surrogate river hydro-scaling approach, another trial release of water from the Mowamba River to the Snowy River occurred during May 2017 to provide carbon and to reduce a-seasonal water temperatures in the Snowy River.

Table 1. Displays the five winter/spring high-flow releases
Release date Volume (megalitres/day)
Wednesday 14 June 4,552 megalitres/day*
Tuesday 27 June 3,324 megalitres/day*
Thursday 13 July 3,552 megalitres/day*
Wednesday 4 October 13,000 megalitres/day* (largest flow event)
Wednesday 15 November 4,121 megalitres/day*

* These high flow events are expressed as an equivalent flow rate. The peak flow rate will occur for eight hours so as to (i) mimic the flashy hydrology of the Snowy and to (ii) promote habitat improvement. These will occur from 7am to 3pm.

The department will issue 'rising river alerts' to relevant media organisations a few days prior to each of the five high-flow events.

Increased flows and targets

Rising river alerts

There were a total of five ‘rising river alerts’ issued during the course of the scheduled winter/spring.