ENVIRONMENTAL
RESULTS
ABOUT THE ZONE
The Western Basin is located near the north-western end of Gladstone Harbour. Three large-scale Liquid Natural Gas (LNG) plants have been constructed on the south-western shore of Curtis Island. The first of these commenced operation in late 2014. Large industrial plants located on the western shore of this zone include Queensland Energy Resources, Rio Tinto Yarwun, Orica, Transpacific Waste and Cement Australia. Areas of mangroves and mudflats remain between Fisherman’s Landing and the Wiggins Island Coal Export Terminal (WICET) and on the southern tip of Curtis Island.
WATER & SEDIMENT
The Western Basin received an overall water quality score of 0.76 (B).
Sediment quality of The Western Basin was very good with an overall score of 0.99 (A).
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The following graphs compare the Water and Sediment scores reported for 2025 (top line) to those from 2024.
WATER
SEDIMENT
Very good (0.85-1.00)
Poor (0.25-0.49)
Good (0.65-0.84)
Satisfactory (0.5-0.64)
Very Poor (0.00-0.24)
No data available
Overall, Water quality in the Western Basin scored 0.76 and received a Good (B) grade, similar to the 2024 Report Card. This score was calculated by aggregating the three sub-indicator and associated measure scores (Physicochemical – pH and turbidity, Nutrients – total nitrogen, total phosphorus and chlorophyll-a, and dissolved metals – aluminium, copper, lead, manganese, nickel and zinc).
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The Western Basin received a Very Good (A) grade for pH (1.00), and Satisfactory (C) grades for turbidity (0.51), total nitrogen (0.53), and total phosphorus (0.60). All six of the dissolved metals received a Very Good (A) or Good (B) grade, indicating that average concentrations for these measures were within the guideline values for this zone. Chlorophyll-a received a Poor (D) grade with a score of 0.45.
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For Sediment quality, the Western Basin received an overall score of 0.99 and a Very Good grade (A), a similar result to the previous year. This score was calculated by aggregating one sub-indicator and associated measure scores (Metal and metalloids – arsenic, cadmium, copper, lead, mercury, nickel and zinc). The results reflect that all concentrations were below the guideline values for this zone.
HABITATS
SEAGRASS RESULTS
Meadow 4
Meadow 6
Meadow 8
Meadow 5
Meadow 7
Meadow 52-57
The Western Basin has six long-term monitoring meadows: five intertidal and one subtidal (Meadow 7). In 2025, this zone earned a Good (B) grade for the seventh year in a row.
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Meadow 4 maintained similar scores to 2024, with all measures graded Very Good (A). Meadows 5 and 6 both showed improvements in biomass, species composition, and overall meadow scores.
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Meadow 7 showed a reduction in biomass score (2024: 0.85, 2025:0.71), but an improvement in area (2024: 0.58, 2025: 0.85). Meadow 8 improved in biomass and area but declined to a Poor (D) grade for species composition.
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In Meadows 52–57, biomass and area scores increased (biomass: 2024: 0.73, 2025: 0.86; area: 2024: 0.87, 2025: 1.00), leading to an increase in the overall meadow score from 0.73 to 0.86 and an upgrade from Good (B) to Very Good (A).
MANGROVE RESULTS
The 2025 Gladstone Harbour Report Card incorporates the 2024 Mangroves results. Mangrove condition has historically remained stable due to strong buffering capacity, and since 2019, monitoring has been undertaken every five years. In 2024, the overall grade for Mangroves in the Western Basin improved from a Satisfactory (C) to a Good (B).
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The mangrove extent sub-indicator, which measures changes in canopy cover relative to saltmarsh and saltpan areas, declined to a Satisfactory (C) grade. The canopy condition indicator, based on remote sensing of canopy density and health, improved from Poor (D) to Good (B). However, shoreline condition, assessed through aerial surveys of mangroves bordering Gladstone Harbour’s water quality zones, remained at a Poor (D) in 2024.
FISH & CRABS
FISH RECRUITMENT RESULTS
Fish recruitment was assessed for two species: Yellowfin bream Acanthopagrus australis and Pikey bream A. pacificus. The overall score for 2025 was higher than the previous year (2024: 0.82, 2025; 0.89) and improved from a Good (B) to a Very Good (A) grade. This is a result of increased catch numbers of both Yellowfin (2024: 12, 2025: 21) and Pikey (2024: 16, 2025: 17) bream.