The Productivity Commission, 2003:

"Many towns and cities (in the GBR catchment) have significant transient populations, particularly due to flows of tourists, with infrastructure developed to facilitate both transient and permanent populations. In total, there are over 100 urban centres adjacent to the GBR World Heritage Area (GBRMPA 2002d). One of the potential sources of pollution arising from human activities includes ‘point source’ pollution from land uses - such as from coastal developments, sewage, port activity, and industrial and mining activities."

AND

"In particular, factors that influence the impact of sewage discharges include the volume and pre-treatment of effluent, dispersal characteristics of the effluent, and location of the discharge. "

AND

"Coastal areas that are more developed and heavily populated can be potential sources of pollutants, particularly excess nutrients, to the GBR lagoon through:

• sewage discharge from treatment plants;
• septic tank contamination;
• industrial wastes and stormwater runoff, containing hydrocarbons, lawn fertilisers and animal waste; and
• discharge of freshwater (carried by stormwater and sewage) to the marine environment (Furnas 2002; GBRMPA, sub. 27, p. 9).

Sewage discharge is the most important of these; its environmental impacts depending on factors such as volume and treatment of effluent, timing of discharges relative to river flows, and the location of the effluent discharge point (GBRMPA, sub. 27, p. 18). EA (sub. DR58, p. 4) commented that sewage outflow can constitute the entire stream flow in some areas in the dry season. There is no inventory of the quantity of nutrients exported to the waters of the GBR lagoon from sewage plants, so estimating these levels is particularly difficult. The estimates in table 2.3 suggest that sewage may account for 6 per cent of nitrogen and 20 per cent of phosphorus loads to the GBR lagoon (with 1928 tonnes of each exported, compared with the ‘upper limit’ estimates of Furnas (2002) — 2250 tonnes of nitrogen and 600 tonnes of phosphorus inputs annually, on average). Furnas (2002) concluded that the large scale impact of sewage on nutrients is likely to be small relative to diffuse sources, although potentially locally significant. Nonetheless, Brodie (sub. DR75, p. 3) suggested that, although the chronic nature of sewage discharge presents different environmental problems to the more episodic nature of agricultural runoff, it should not be ignored."

AND

"In terms of management practices, the majority of large coastal cities, and most smaller coastal and island settlements adjacent to the GBR, have secondary treatment sewage systems which reduce the organic loading in effluent (GBRMPA, sub. 27, p. 8). Several coastal sewage treatment plants use some secondary treated effluent for land irrigation (AFFA, sub. 53, p. 16). That said, some areas still use septic systems, including parts of Cooktown and Malanda."

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Citation and/or URL

Productivity Commission 2003, Industries, land use and water quality in the Great Barrier Reef catchment: research report. Department of Communications, IT and the Arts, Canberra, Australia.

Spatial Coverage

Great Barrier Reef

Temporal Coverage

2003

Update Frequency

Other Information

 None