Burrows, Damien, Faithful, John, Kutt, Alex, Tait, Jim, and Blunden, Lynda (1999) Environmental study of a proposed dam at Mount Douglas on the Belyando River. Report. James Cook University, Townsville, QLD, Australia.

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Abstract

[Extract] Within the Burdekin River Catchment, suitable locations for further water infrastructure development are being considered. One of the options is a potential dam site at Mt. Douglas on the Belyando River, 10km upstream of its confluence with the Suttor River. The Belyando River catchment is the driest in the Burdekin basin and most of the recorded streamflow results from episodic large events. Despite its aridity, there are numerous in channel waterholes and off-river waterbodies in the lower reaches of the river and below its confluence with the Suttor River. The inundation area contains several of these waterholes.

This report provides a preliminary assessment of the likely environmental impacts of a dam at Mt. Douglas. Six permanent waterholes were examined during a brief field visit. Five of these were sampled for fish, crustaceans and water quality. A total of 12 fish species were caught, including two translocated predatory species (yellowbelly and sleepy cod). The two translocated species appear to be impacting on the abundance and diversity of smaller prey fish species. These smaller species were more abundant at off-river water bodies where the larger predatory fish were absent or in low numbers. Four fish species recorded for the Belyando River at Mt. Douglas in 1976 were not caught during this field survey. Failure to collect these four species may reflect insufficient sampling effort, but is more likely to reflect other factors such as altered habitat conditions and the effects of translocated piscivorous species.

Due to the topography of the site, a dam at Mt. Douglas would be a large, shallow impoundment with a greatly fluctuating shoreline. Hydrological data suggest that the dam would capture a significant proportion of medium-large flow events and most of the smaller flow events, thus altering the pattern of streamflow downstream and restricting options for fish passage within the catchment. Any dam at Mt. Douglas is likely to be even more turbid than the existing Burdekin Falls Dam and to have higher nutrient concentrations. The Belyando-Suttor is a major supplier of fine suspended sediment to the Burdekin Falls Dam which maintains that reservoir in a permanently turbid state, or essentially so. If a dam at Mt. Douglas reduces dry season flows such that water clarity improves in the Burdekin Fall sDam, then this should have a significant effect on its limnology. In some instances, this maybe beneficial but it is also likely to cause blue-green algal blooms. As water is released over much of the year for irrigation, the changes in water quality will also affect downstream receiving environments (eg, coastal wetlands) as well as the impoundment itself. The Suttor and Cape Rivers are not captured by this proposed dam and turbid discharges from these rivers may mask the effects of Mt. Douglas dam, but at present, there is insufficient data to test this idea.

Twenty-one regional ecosystems have been mapped for the impoundment area, including three listed as endangered and ten listed as of concern. In addition, one of the properties (Nairana) with a significant amount of land to be inundated, has recently been purchased by the EPA for a National Park. Apart from the previously identified issues, this last issue, above all, suggests that the Mt. Douglas site is not suitable for a dam development.

Item ID:	36932
Item Type:	Report (Report)
Additional Information:	Report 99/28
Date Deposited:	05 Dec 2016 23:36
FoR Codes:	05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050205 Environmental Management @ 100%
SEO Codes:	96 ENVIRONMENT > 9606 Environmental and Natural Resource Evaluation > 960604 Environmental Management Systems @ 100%
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