History of Belmont Lagoon: 1920-2020

Belmont Lagoon: description and context

This open water body, located at 33°02’39”S, 151°39’48”E, lies between the Pacific Ocean and Lake Macquarie in the community of Belmont, in the Lower Hunter Region of NSW. Colonial survey maps first described it as a freshwater site; today it is known to be part of an extensive system of coastal wetlands connected with the north-eastern part of Lake Macquarie in New South Wales (1)

Belmont Lagoon wetland starts south of Charlestown. Freshwater swamps and creek-lines meander south-east through the suburbs of Bennetts Green and Jewellstown, ultimately reaching either Lake Macquarie via swamplands in suburban Pelican and Marks Point, or the lagoon at Belmont, or Nine-Mile Beach into the Pacific Ocean when 3rd Creek breaks through its foredune.

By 1920 the water body was identified as a freshwater lagoon on Portion 143 in the coastal town of Belmont in the Parish of Kahibah, approx. 20 km south of Newcastle. The town’s name is thought to be linked to Belmont House (2) in the Shetland Islands north of Scotland, from where Thomas Williamson and family emigrated in 1838. He played a key role in developing Belmont in the 1860s.

Belmont Lagoon as it was later called has been a designated recreation reserve in the City of Lake Macquarie (3) since 2001, but nearly 50 years ago an unspecified source in the Newcastle Morning Herald (4) claimed:

“little had been recorded in official files about the early history of the lagoon, except references to it being a favourite meeting place for one tribe of the Lake Macquarie blacks.”

This not only neglected the lagoon’s broader ecological impact on Lake Macquarie but also reflected a general lack of interest in Aboriginal cultural ways at that time. To re-examine the lagoon’s environmental status, it is helpful to understand some basic ecology, geomorphology and hydrology of coastal wetlands; some features of water bodies (lagoons, marshes and swamps) and their role in Lake Macquarie’s bio-health.

Ecology of Belmont Lagoon and coastal wetland environs

This lagoon is described as oval in shape and is 900 metres by 650 metres wide and is of shallow depth. It was a freshwater wetland for over 7000 years (5). These features are examined more closely in this report.

Wetlands are broadly defined (6) as areas of land which are permanently or temporarily inundated by shallow water (less than 2m) or waterlogged, inundated or saturated. These may contain other natural water resources (marshes, bogs, swamps, lagoons). Each has distinguishing features. Hydrology of wetlands (7) is usually stated as freshwater, brackish or saline. Marshes are defined as wetlands dominated by herbaceous plants (grasses, rushes or reeds) often found at the edges of lakes and streams where they form a transition between aquatic and terrestrial ecosystems. Swamps are defined as wetlands dominated by woody plants - dominant shrubs or forest canopy species.

Wetlands improve water quality of a lake or lagoon by acting as a sink to filter pollutants (phosphates and heavy metals) from the water flowing through them. Marshes and other wetlands can absorb water during periods of heavy rainfall and slowly release it into waterways, thus reducing the impact of flooding (mobile surface water). The pH in marshes tends to be neutral or slightly alkaline, whereas in bogs peat accumulates under more acidic conditions.

By its ecological features and location, Belmont Lagoon is not an isolated natural asset like an oasis or freshwater spring, but part of a broader wetlands system (8) . Evidence of this broader system is supported by a cartographic map (9) of this freshwater lagoon in the north-eastern (NE) corner of Lake Macquarie dated 1942. The brown contours of frontal dunes east of the lagoon may have been up to 40 m Australian Height Datum (AHD) prior to extensive sand extraction operations in the 1970s. Their distinctive contours pointing NNW indicate the effects of strong and persistent SE winds and storm surges.

Other symbols or cartographic codes on that map include:

• green spots (of different densities) north and south of the lagoon and on the dunes to the north-east indicating dense, medium or scattered timber;
• green m-shapes (like flying birds) to the south representing low scrub;
• blue clumps around the lagoon and elsewhere representing swampy areas underfoot (with or without vegetation); these may dry up in drought or summer.

Mangroves and marsh plants are said to facilitate the accumulation of sediment in a lagoon. Belmont Lagoon Reserve consists of five main biotic areas including swamp sedgeland and open water attracting a range of native birds and marine life.

Geomorphology of Belmont Lagoon

An inventory of Lake Macquarie Wetlands (6) in 1989 outlined the geomorphology of Belmont Lagoon Wetlands (wetlands plus catchment area for SEPP 14). Its hydrology type was described as ”estuarine/palustrine.” Estuarine means the mixing of saline and fresh water which, in turn influences the vegetation and soil chemistry. Here, significant fresh water (rainfall, creeks, stormwater drains) flows into this lagoon (wetlands area 220 ha). Palustrine indicates the lagoon receives water only from a relatively small local catchment area (900 ha), and not from any estuary. Its salinity was rated saline/brackish. This is an important, gradual change from its original freshwater status, which was changed mechanically in 1942 (10) by linking it to Lake Macquarie’s tidal influence via Cold Tea Canal.

The 1989 inventory rated the Lagoon’s average water depth as moderate (10 cm-1 m). An independent profile (11) map (1986) recorded depths ranging from 230-750 mm at 14 spots in the northern part of the lagoon, but none in the southern sector. Recent photographs of waders and shorebirds standing in the northern part suggest it is shallower in 2020. The Lagoon may be silting up, but this is uncertain without other reference markers. The ground water table is high and, typical of coastal wetlands, is affected by drought and inflows of both fresh and tidal water (3). LiDAR measurements from aerial photographs by Lake Macquarie City Council cannot indicate water depth, but they can yield other data (water surface area, vegetation monitoring) for selected wetlands.

Originally the lagoon site may have been part of a coastal swamp. Remnant forest (eg. Broad- leafed Paperbark Melaleuca quinquenervia) are still dominant vegetation on its north-western side and surrounds. Or it may have been part of an extensive system of freshwater marshes fringed by Swamp Sheoak Casuarina glauca). This idea is supported by notes and a sketch of Portion 66 by Mary Boyes (great grand-daughter of Peter Fleming who purchased that land in 1870). She wrote (of her childhood holidays at Belmont South in the 1920s): “the majority of that land was swampy, taking in much of the low-lying area west of the freshwater lagoon at Belmont” (12).

Soil type is another geomorphological feature of this lagoon. Surrounding the lagoon is aeolian (wind- driven) sand (13), the Tuggerah soil landscape, and beach ridge sand flats, the Woy Woy soil landscape (14).

The 1942 map cited above may support this formation process, but not its geological period nor duration. For example, there are no obvious hind dunes (brown contours) represented near the SE corner of the Lagoon, yet there are substantial hind dunes further north-east. Taken together these data could suggest the Lagoon’s sandy base and large hind dunes (with NW oriented contours) to its east and north are due to strong storm wind and wave action over many centuries. This process loosens foredune sand, which strong or steady onshore winds carry landwards. This sand can smother existing or introduced vegetation which otherwise binds the soil (15).

Even today (2020) a drive along Nine-Mile Beach, the eastern-border of Belmont Wetlands State Park, reveals substantial areas of sloping frontal dunes with little or no vegetation. These dunes have a maximum height of approximately 20 m AHD (16).Geological evidence later in that report indicates this movement may have occurred for 7000 years. It continues today and is related to sea level changes. The soil type of the lagoon itself is that of a swamp, the Belmont Lake soil landscape, one of level to gently undulating coastal swamps with local relief less than 5 m, slopes less then 2% and watertable at less than 100 cm. This soil landscape has a hummocky topography, shallow lakes and watertables, and is vegetated by closed sedgeland and tall open forest. The soils are integrades between deep acid peats and siliceous sands.

Social and industrial history of the lagoon

In this latest period (1920-2019), Belmont’s social history as a holiday and retirement destination was eclipsed by its ‘industrial potential’. In 1925 Broken Hill Pty. Ltd.(BHP), the fourth coal-mining company to operate in this area, opened the John Darling Colliery #4 at Belmont North. Their land included the lagoon itself and in 1970s a ventilation shaft was sunk in the middle of it for mines operating 200-300 m below ground. An artificial dirt peninsula and track were constructed to convey equipment to install and maintain that shaft. This means none of the vegetation along that artificial peninsula is remnant coastal scrub. Some flora are indigenous to NSW; others are not (e.g. from WA)) – all were planted.

Newspaper reports indicate that coal mining under the lagoon had mixed fortunes. Problems included poor ventilation and water in some sections (SMH 12/3/1937) and fire and gas in the tunnel (SMH 11/5/1942). Flooding the mine was decided as the safest method to extinguish the latter. The colliery closed in 1987 and BHP handed back the 514 ha site to the N.S.W. government in 2002 (5).

In 1942 the lagoon underwent further geographical modification, as part of defensive preparations during World War 2 against a possible Japanese invasion (10) by sea. In the process, the hydrology of the once-fresh water lagoon was changed. Its narrow overflow creek into Lake Macquarie was widened and dredged into a canal extending to the eastern side of the lagoon. A causeway or track was later built beside the canal (aka Cold Tea Creek) and short, wide concrete pipes under the track enabled water to move between the lagoon and this canal. Tidal flow from Lake Macquarie resulted in the lagoon changing inevitably from fresh water to saline, despite stormwater and other inflows.

Australia’s south-eastern states endured several severe droughts (17) during this period. During the drought of 1939-45 a local newspaper (18) reported that Belmont Lagoon dried up, stating “old residents of Belmont cannot remember when the lagoon was as dry as the present. They cannot account for it, and recall other long dry spells that did not affect the height of the water in the lagoon to any great extent. It is suggested that probably the using of water from the catchment by the John Darling Colliery may have something to do with it. Much annoyance was caused to residents living in the vicinity during the drying up process by the unpleasant odours which came from the mud.”

Obviously this was a strong social concern. Its legacy today – from connecting the lagoon to Lake Macquarie via Cold Tea Canal - is that daily tidal flows will likely prevent a repeat occurrence even in severe drought, although north-eastern mud flats remain exposed under certain conditions.

In 2016 Hunter Water Corporation upgraded its pipeline and dirt tracks on the eastern side of the lagoon. Lake Macquarie City Council (19) (LMCC) is currently promoting this area as a location for passive recreation (walking, birdwatching and cycling) and a fauna sanctuary. It was a different story circa 1913, as a local newspaper reported. “There is a large lagoon on the eastern side of Belmont, which for many years was the breeding place for all kinds of wild fowl. Unfortunately the lagoon became so thoroughly exploited for the game it afforded, and the guns killed off such a quantity, that the spot became practically denuded of birds.” All this was still occurring a decade after legislation (the Native Animals Protection Act 18 1903) was introduced by Parliament.

Recent studies (20) have shown a steadily increasing number and variety of native bird species in this area. Belmont Wetlands State Park’s Plan of Management (5) also comments on the lagoon’s biotic evolution.

The vegetation communities associated with Belmont Lagoon have been altered by the brackish water conditions that have prevailed over the past 67 years [since 1942] and the vegetation and associated fauna are typical of a natural succession found on the shoreline of a fresh to brackish lake. One of the distinctive features is the large body of water surrounded by a diversity of biotic communities formed under the previous freshwater lagoon conditions including Swamp Forest, Swamp Heath, Reed Swamp and Sedge Land. The open water areas contain seagrass species with Grey Mangroves and saltmarsh species around the edges associated with the increase in marine saline waters (City of Lake Macquarie, 2001).

This work by Lake Macquarie City Library is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License