ENVIRONMENTAL
RESULTS
ABOUT THE ZONE
The Boyne River is dammed at Lake Awoonga to provide potable water for the Gladstone area. Large numbers of barramundi are stocked in Lake Awoonga and may be introduced into the Boyne Estuary when the dam overtops. The Boyne Estuary was the site of large-scale mortality of many of these introduced barramundi and other fish in 2011. The lower reach of the Boyne River flows from the dam through predominately agricultural land that has pockets of remnant vegetation. Before entering the south-eastern section of the Mid Harbour Zone the Boyne River flows through the residential communities of Boyne Island and Tannum Sands.
WATER & SEDIMENT
Boyne Estuary received an overall water quality score of 0.84 (B).
Sediment quality of Boyne Estuary was very good with an overall score of 0.97 (A).
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The following graphs compare the Water and Sediment scores reported for 2024 (top line) to those from 2023.
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 Boyne Estuary improved in score to 0.84 and maintained a good grade (B). This score was calculated by aggregating the three sub-indicator and associated measure scores (Physicochemical – pH and turbidity, Nutrients – total nitrogen, total phosphorus and dissolved metals, and dissolved metals – aluminium, copper, lead, manganese, nickel and zinc).
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Within the Physicochemical sub-indicator, Boyne Estuary received a score of 1.00 and a very good grade (A) for pH, indicating that pH was within the guideline value range. The turbidity grade improved from very poor (E) in 2023 to a satisfactory (C) in 2024, indicating that turbidity was within the guideline value range for this zone this year.
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Within the Nutrient sub-indicator group, total nitrogen (0.31) and chlorophyll-a (0.44) both received a poor grade (D), indicating that these measures were above guideline values. In contrast, total phosphorus (0.78) received a good (B) grade, indicating that this measure was below the guideline values.
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All six Dissolved metals received high scores (1.00) and very good grades (A) indicating that they were well below the water quality guideline values.
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For Sediment quality, Boyne Estuary received an overall score of 0.97 and a very good grade (A), a similar result to the previous year. This score was calculated by aggregating measure scores (Metal and metalloids – arsenic, cadmium, copper, lead, mercury, nickel and zinc).
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In 2024, six of the seven Metal and metalloid sub-indicator measures received very high scores (1.00) and very good grades (A), and one sub-indicator – arsenic – received a high score (0.81) and a good grade (B), indicating that these measures were well below the guideline values for this zone.
HABITATS
MANGROVE RESULTS
Boyne Estuary has one Mangrove monitoring zone. In 2024, Mangroves at Boyne Estuary scored 0.66 and received a good grade (B), an improvement from poor (D) in 2019, due to improvements in scores and grades for all measures. Mangrove extent improved from a poor grade (D) in 2019 to a satisfactory grade (C) at Boyne Estuary, indicating a net gain of mangrove area. The grade for canopy condition improved from very poor (E) in 2019 to poor (D) in 2024. Shoreline condition of mangroves at Boyne Estuary improved several grades from a very poor (E) in 2019 to a very good (A) in 2024.
FISH & CRABS
FISH RECRUITMENT RESULTS
Fish recruitment was assessed for two species: Yellowfin bream Acanthopagrus australis and Pikey bream Acanthopagrus pacificus. In 2024, the overall Fish recruitment grade for Boyne Estuary improved from poor (D) to satisfactory (C).