A large scale project aimed at improving safety at the South Dubbo weir is also a huge win for the health of the Macquarie River, with native fish set to benefit immeasurably.
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For decades the large concrete structure has not only been a major safety concern for river users, but has also interrupted the natural breeding migration of native fish species such as golden perch (yellowbelly), Murray Cod and the endangered trout cod.
The South Dubbo weir structure was labelled a high priority site in need of works to address the lack of fish passage after a detailed review into weirs in the NSW central west.
The study discovered that due to many factors, including the height of the structure and the lack of "drown out" time where native fish could move up river, the South Dubbo weir was of a high priority ranking.
In a media release issued in March, Dubbo City Council stated it has committed to the construction of safety improvement works at the South Dubbo weir by the summer of 2015/2016 including the construction of a rock fill ramp and a fish way following a recommendation endorsed by council at its March meeting.
Mayor of Dubbo, Councillor Mathew Dickerson, said the rockfill ramp with toe protection will involve the placement of large rockfill immediately downstream of the weir up to an assumed height of 0.5 metres below the crest of the existing spillway.
"The idea of the rockfill ramp is to place large rocks against the downstream face of the weir to dissipate the energy of the cascading water gradually over a distance of about 20 metres," Cr Dickerson said.
"Once the rockfill ramp is in place, the existing low flow spillway will be in filled with concrete and a new low flow spillway 2 metres wide and 0.1 metre deep will be constructed in its place adjacent to the right bank in order to raise the spillway crest to spread the water flow over a wider width of weir."
Written reports of fishways date back to 17th-century France, where bundles of branches were used to create steps in steep channels to bypass obstructions.
A version was patented in 1837 by Richard McFarlan of Canada who designed a fishway to bypass a dam at a water-powered lumber mill.
In 1852-1854, the Ballisodare Fish Pass was built in County Sligo in Ireland to draw salmon into a river that had not supported a fishery.
