News · Water quality · Lake Macquarie

Lake Macquarie’s basins kept their A grades, and a marine pest alga, Caulerpa, was observed at Wangi for a third year

The 2025-26 report card, prepared for the council by the NSW environment department, gives the lake’s basin and bay zones and Swansea Channel A grades again; Cockle Creek, Dora Creek and Fennell Bay scored B. The grades are worked out from October to April, and this time that season had about half the previous season’s rain. The report recommends more monitoring for Caulerpa. The council’s release of 30 September did not mention it.

The Hunter Ledger · 9 October 2026 · 3 primary sources, read 9 October 2026

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The short answer. On the measures the report card uses, the open lake is in very good health. The Estuary Report Card 2025-2026, written by the NSW Department of Climate Change, Energy, the Environment and Water (DCCEEW) for Lake Macquarie City Council, which funds the program, gives the northern, southeast and southwest zones and Swansea Channel an A for overall water quality, as they have had every year since 2012-13 on the report’s own tables. The two creeks that feed the lake and the enclosed Fennell Bay scored B overall. The council announced the results on 30 September, saying Results for 2025-2026 revealed all monitoring zones maintained the same grades recorded in the previous year. That is right for the overall grades. Two findings in the report did not make the release: an invasive marine alga at Wangi, and seagrass in Fennell Bay that has never reached a B.

One thing the card is not: a swimming guide. It grades cloudiness (turbidity), algae (chlorophyll-a) and how deep seagrass grows, and it reports nutrients. None of the measures listed in its method is a bacteria count, so it says nothing about whether a particular beach is fine for a swim on a particular day.

The grades, zone by zone

The report grades seven areas. Each gets a grade for turbidity and for chlorophyll-a, which are averaged into a water quality grade; where seagrass is surveyed, seagrass depth range is blended in (70% water quality, 30% seagrass) for an overall ecological health grade. Grades run from A (very good) down, and the report says an A is equivalent to the best 20% of scores across NSW estuaries.

Three indicator grades moved. Seagrass in the southwest zone, measured at Chain Valley Bay, grew its depth range by 0.25 metres to 1.88 metres and went from C to B. In Cockle Creek, turbidity exceeded the state trigger value on six sampling trips and dropped a grade to C, while chlorophyll-a rose to B for the first time since 2017-18; the creek’s overall grade stayed B. Everything else held.

A dry season to be graded in

Water quality grades are worked out from samples taken in the warmer months, October to April. The report is plain about what that window was like this time: Lower than average rainfall occurred from October 1, 2025, to April 30, 2026, and the grading season had about half the rain of the one before, 545 millimetres against 1,009. It adds that Very little rain fell prior to most sampling days, and that the dry weather may partly explain Cockle Creek’s better chlorophyll-a grade, because algal growth in its shallow water can be amplified after rain, in response to nutrients in runoff from a highly urbanised catchment.

That cuts two ways, and the main lake comes out of it well. The northern, southeast and southwest zones and Swansea Channel scored A for overall water quality in 2020-21 and 2021-22 too, the two wettest grading seasons in the table, so their A is not an artefact of one dry summer. The creeks are a different matter: a better chlorophyll-a grade in Cockle Creek in the driest season on the table is weak evidence that anything in its catchment has changed, and the report itself ties it to the weather. Its nutrient figures, for July to December 2025, show total phosphorus and total dissolved phosphorus in Cockle Creek above the state trigger values on every sampling trip.

Caulerpa at Wangi, for the third year

The report’s seagrass discussion records that the exotic green alga Caulerpa taxifolia was observed at Wangi for the third year in a row. The seagrass sites were surveyed in May 2026. The report explains why that matters:

Its recommendation is one sentence: It is recommended that additional monitoring is undertaken to monitor the presence of Caulerpa within the lake. The report does not say how much Caulerpa was seen, or where around Wangi, and the council’s 30 September release, which we read in full, does not mention Caulerpa at all. Wangi is one of five seagrass sites surveyed once a year, so the observation is about one site, not a survey of the whole lake.

Fennell Bay’s seagrass has never scored a B

Fennell Bay, the enclosed bay off the northern lake, keeps getting good water. It scored A for water quality this year. Its seagrass does not follow. The survey found seagrass there hard to see because of its sparse distribution and tiny size, and the depth range fell by 0.08 metres to 0.47 metres, a D. The report’s summary: The seagrass site in Fennell Bay has not scored an A or B grade for seagrass depth range since monitoring began, despite consistently receiving A and B grades for water quality, suggesting other factors may also be impacting seagrass distributions in the bay.

The report names candidates rather than a cause. Fennell Bay is an isolated bay end with little flushing, which it calls one of the more sensitive parts of the lake; nutrient and sediment inputs from the urban and industrial catchment have likely affected the sediment, it says, and boat mooring and boating activity in the bay may also be playing a part.

What the release said, and what the report says

The council’s own report card web page does give the rain the report’s way round: Yearly rainfall between the sampling period of July 2025 to June 2026 was relatively consistent with long-term averages, although there was higher than average rainfall recorded in July, August, January and May. Neither the page nor the release mentions Caulerpa.

Our view

This section is opinion, built on the facts above.

The headline result deserves the council’s satisfaction. The open lake has scored A for water quality for 14 straight seasons on the report’s tables, through the two wettest grading seasons on record in them as well as this dry one. That is a long, consistent result from a state agency using a statewide method, and residents can take it at face value.

The release, though, is a selection, and it left out the two findings that ask something of the council. A marine pest seen at the same site three years running, with a recommendation from the scientists the council pays for more monitoring, is the kind of thing ratepayers who boat and swim at Wangi should hear about from the council, along with whether it will act on the recommendation. Fennell Bay’s seagrass has not reached a B in 15 seasons while its water quality consistently scores A or B, and the report suggests other factors, sediment and boating among them, may also be at work. Both are management questions, and a good-news release is not the place they get answered. The clarity figure is the smaller point, but a public body should be able to say where a number comes from, and say 2.4 times when it means it.

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