There are numerous dams and associated lakes in the GBR catchment, some of which are very large, with major impacts on large rivers such as the Burdekin dam, while some are small, and with impact only on small parts of the catchment such as the Paluma dam (Brodie et al. 2009).

Immediate impacts

Brodie et al., 2009:

"The immediate impact of dams on habitat include the drowning of running water systems, providing lagoons and lakes where previously there were streams and rivers, often impeding connectivity for migrating organisms, and drowning important riparian zones that provide habitat and connectivity for terrestrial and semi-terrestrial organisms. Habitats downstream are affected by reduced flows during flow events and, if the river channel is used to deliver water downstream, by increased flows during dry periods and other issues such as fluctuation in temperature and dissolved oxygen. Such alterations in flow regime can have severe effects on breeding regimes of fish, turtles, etc.,, on species survival and can have indirect effects such as the encouragement of weed infestation. There may also be several impacts of water infrastructure on water quality. Deep water stratifies thermally, often producing cool hypoxic conditions at the bottom of the water body, rendering much of it uninhabitable by fish and other biota. When this water is released downstream or mixes with the overlying water column, severe effects on the biota can be experienced. Still waterbodies can be prone to algal blooms, especially when there are excess nutrients available, so in some circumstances water in storages can become toxic to domestic stock and wildlife."

Altered river flow regime

Brodie et al., 2009:

"A reduced input of water to the river may result in a reduction in the the degree of flushing necessary to maintain oxygenated conditions. Conversely supplemented flow may cause flushing where normally still waterbodies would develop. In either case, alteration in the normal flow regime produces a different environment with a changed water quality regime and associated biota. Most rivers in the GBR catchment that have dams on them are affected in one or all of these ways, although there is mostly only anecdotal evidence to support this. Only in situations where dams are high in the catchment (e.g. Paluma) are effects relatively small at the whole-catchment scale.

Much of the stored water in Queensland is used for irrigation. This use changes water delivery through a catchment by increasing flows when stream might otherwise be dry, both upstream of the irrigated land (via natural delivery pathways) and downstream (via drains). Drains typically are contaminated with nutrients, pesticides and sometimes sediments, which affect downstream waterways and wetlands. Such impacts can be negative through promoting weed growth and hypoxia (e.g. in the Burdekin floodplain – Perna 2005 cited in Brodie et al. 2008; Perna and Burrows 2005 cited in Brodie et al. 2008) and in making temporary wetlands permanent, but can be positive in supplementing available habitat."

Other Infrastructure

Brodie et al., 2009:

"Road crossings can be a source of sediment and other contaminant input into streams. There is little available information on this issue. There is limited information on the effects of culverts and bridges on connectivity within streams: in small lowland streams and wetlands, culverts prevent migrations of some fish species (Perna 2005; Kapitske 2007), and it is possible that there are similar impacts in otherwise quite pristine upland streams."

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Citation and/or URL

Brodie, J., Pearson, R., Lewis, S., Bainbridge, Z., Waterhouse, J. & Prange, J. 2009, Water quality research: baseline synthesis and year 1 summary: a report to the Marine and Tropical Sciences Research Facility (MTSRF). Reef and Rainforest Research Centre Limited, Cairns, Australia

Spatial Coverage

Great Barrier Reef catchment and lagoon

Temporal Coverage

2008

Update Frequency

Not applicable 

Other Information

None