Our water quality monitoring program has shown Middle Harbour Creek to have good water quality. Find out more about the estuary and its unique features.
Middle Harbour Creek is situated in the Sydney Metropolitan region of New South Wales. It is classed as a drowned valley estuary and flows into Port Jackson/Sydney Harbour.
The creek flows through a wooded valley flanked by Sydney’s North Shore suburbs. The estuary and its surrounds are a popular recreational place for activities such as birdwatching, walking, picnicking, boating, fishing, and kayaking.
As part of our water quality monitoring program we assess the water quality and ecosystem health of an estuary using a range of relevant indicators. We sample a subset of the estuaries located between Taree and Wollongong every 3 years. The most recent sampling in the Middle Harbour Creek was completed over the 2019–20 summer when 2 sites were sampled on a monthly basis.
This report card represents 2 water quality indicators that we routinely measure: the amount of algae present and water clarity. Low levels of these 2 indicators equate with good water quality.
The report card shows the condition of the estuary was good with:
Find out more about our estuary report cards and what each grade means. Read our sampling, data analysis and reporting protocols and find out how we calculate these grades.
We have monitored water quality in Middle Harbour Creek since 2010. This table shows the water quality grades for this estuary over that time.
Grades for algae, water clarity and overall are represented as:
As part of our Beachwatch program we assess swimming suitability at 7 swimming sites in Middle Harbour Creek using microbial indicators. We collect samples at each site weekly between October and April, and monthly from May to September, to calculate the suitability grade. Sampling is ongoing. Each grade reflects the most recent 100 water quality results to April 2022. Find out more about how we monitor beach water quality.
| Local government area | Swim site name | Grade |
|---|---|---|
| Northern Beaches | Clontarf Pool | Good |
| Gurney Crescent Baths | Fair | |
| Davidson Reserve | Poor | |
| Willoughby | Northbridge Baths | Poor |
| Mosman | Chinamans Beach | Good |
| Edwards Beach | Good | |
| Balmoral Baths | Good |
Estuarine, lake and lagoon water can sometimes be unsuitable for swimming, especially after rainfall when stormwater and wastewater can overflow into swimming areas. Learn more about what the grades mean and how we grade swimming sites on our beach classification webpage.
Estuary type: Drowned valley
| Entrance location |
Latitude (ºS) | –33.82 |
|---|---|---|
| Longitude (ºE) | 151.26 | |
| Catchment area (km2) | 77 | |
| Estuary area (km2) | 6.1 | |
| Estuary volume (ML) | 81,900 | |
| Average depth (m) | 13.4 | |
Bathymetric and coastal topography data for this estuary are available in our data portal.
Most of the land within Middle Harbour Creek catchment is occupied by urban development associated with the northern suburbs of Sydney. Around one third of the catchment remains forested, a lot of which is protected as part of Garigal National Park. Much of the riparian zone remains intact in the middle and upper reaches of the estuary.
Local councils manage estuaries within their area unless the estuary is attached to a marine park. Northern Beaches Council and Ku-ring-gai Council co-manage this estuary.
Middle Harbour Creek estuary and surrounding bushland provides important habitat for the endangered southern brown bandicoot.
Read more about the biodiversity in our estuaries.