Visual recreation;
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Drinking water;
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Industrial use; and
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Cultural and spiritual values.
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The Dee River is classified as highly disturbed from the Mount Morgan Mine to the confluence of the
Don River. ARD is the key environmental concern at the mine site, posing a significant adverse risk to
downstream catchments, namely the Dee, Don and Dawson rivers. ARD is caused by oxidised sulphide
minerals in rocks and soils being mobilised by water moving over or through the sulphide minerals
(Unger et al., 2003). This sulphidic waste material was dumped across a large area, including the slopes
of relatively steep hills in the upper reaches of the Dee River catchment – factors which have facilitated
its oxidisation and transport offsite.
Sulphide minerals have been exposed to weathering for more than 100 years in some parts of the mine.
Inadequate past mine management practices have left the Dee River in a poor state, where pH is as
low as 2.8. High metal concentrations have been recorded in the Dee River next to the mine site during
periods of low flow (Wels et al., 2007). While there is no recent evidence of acidic flows extending
beyond the Dee River catchment into the Don, Dawson or Fitzroy rivers, there are anecdotal reports of
acidic flows extending into the Dawson River when the mine was still working (GreenGold, 2021).
River water quality monitoring indicates impacts from the Mount Morgan mine site are most prevalent
in the first 20 km downstream (AARC, 2017a). The diversity of species in this section of the river is
greatly reduced, however some species do exist. The water quality in the Dee River continues to
improve with distance downstream as it is diluted by other freshwater catchment inflows. Although
contaminated water seepage from the Mount Morgan Mine has a high level of sulphates (salts), the
water quality at the lower end of the Dee River is suitable for irrigation and livestock. The water quality
in the Dee River improves with distance downstream as it is diluted by large freshwater inputs further
down the catchment. Water quality at Duaringa (140 km downstream of Mount Morgan) is suitable for
potable use (GreenGold, 2021).
The DSITI Guidelines for draft environmental values and Water quality guidelines for Fitzroy Basin
fresh, estuarine and marine waters, including Keppel Bay (Newham et al. 2017) identify the Dee River
as a highly disturbed ecosystem with modified environmental values and water quality objectives.
Contaminated water seepage and runoff from the Mount Morgan Mine is currently managed by the
State via the seepage interception system. While this has reduced contamination loads, the system
cannot collect all contaminated water and water quality values in the Dee River remain adversely
affected. The effects of this can be observed in monitoring data downstream from the Mount Morgan
Mine in the Dee River.
Due to impacts from the Mount Morgan Mine, water in the Dee River is not suitable for drinking or
recreation, such as swimming or fishing. The DNRMMRRD have placed signage at all crossings along
the Dee River advising no drinking, no swimming and no recreational activities. No wetlands of
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Wulguru Technical Services Pty Ltd – Supporting Information to Amend an Environmental Authority
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