New State Government data highlights significant differences between the health of the region's major estuaries.

Lake Macquarie scored an A or very good rating. The result reflects the consistent improvements that have occurred in the lake's environment since the end of commercial fishing in the early 2000s

The result mirrors Lake Macquarie council's monitoring results, which found all but one of seven zones across the lake and its major tributaries achieved the highest possible overall grade for water quality.

Swansea Channel, Fennell Bay, Dora Creek and the south-west, south-east and north zones all achieved an "A" grading. Cockle Creek was the only zone that did not achieve an "A".

The Hunter River Estuary was graded as C, or poor, in the latest Department of Planning, Industry and Environment report card.

The report showed that while algal blooms were relatively low, water clarity across the 47 square kilometer estuary was problematic.

Erosion and the impact of run-off from industry and urban areas contributed to poor clarity.

The region's other major estuary and tourism drawcard, Port Stephens, was ranked as B, or good.

The 134 square kilometre estuary had relatively few algal problems and excellent water clarity.

Seventy one per cent of the estuaries surveyed across the state had good or excellent grades.

The new Health of our Estuaries Report complements the Beachwatch program, which shows which beaches are safe to swim at.

Scientists measure two key estuary stressors - nutrients and sediment - which can lead to nuisance algal blooms or sedimentation that affects the survival of seagrass communities.

"Ecological health is not just an indicator of water quality, it reflects how 'healthy' an estuary is," Local Government Minister Shelly Hancock said.

"This important work can now be accessed online and is the culmination of monitoring and scientific collaboration with coastal councils that began more than 12 years ago

The NSW estuary monitoring program is funded by the Marine Estate Management Strategy.

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