Transcript

Sandringham Lagoon Catchment Story

This map journal is part of a series prepared for the catchments of Queensland.

Map Journal for Sandringham Lagoon - Water movement

 

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This Map Journal describes the location, extent and values of the Sandringham Lagoon. It demonstrates the key features which influence water flow, including geology, topography, rainfall and run-off, natural features, human modifications and land uses.

Knowing how water moves in the landscape is fundamental to the ongoing sustainable management of the Lagoon and the values it provides.

Photo: Sandringham Lagoon - provided by Catchment Solutions

Sandringham Lagoon

Sandringham Lagoon is a 2.2 km long wetland located at the headwaters of Sandringham Creek in Balberra, South of Mackay.

It sits within the Lower Sandy Creek subcatchment, which is a mostly flat (20 to 10 metres ASL) alluvial floodplain comprised of clay, silt, sand and gravel. The Lower Sandy Creek subcatchment sits within the Plane Catchment.

The Lagoon is a unique floodplain lake characterised as a lacustrine system that appears to be connected to an underground spring in the upper reach of the catchment.

Diagram illustrating coastal and subcoastal floodplain lake systems - provided by WetlandInfo.

Values of Sandringham Catchment

The township of Balberra is located in the catchment. The lagoon is important to the surrounding sugar cane farming areas, with some irrigation water being provided for the surrounding farmlands.

After heavy rainfall, the lagoon also acts as a natural retention basin for runoff, helping to slow down the movement of sediment, nutrients and and pollutants. This is important because the lagoon has connectivity that continues downstream until it reaches the Great Barrier Reef (GBR) and excess sediment and pollutants can have negative impacts on the health and biodiversity of the GBR ecosystems.

Values of Sandringham Catchment

Aquatic plants such as Persicaria attenuata are common within the lagoon, which contributes to the habitat for a wide range of species. The lagoon is known to have a variety of migratory fish, waterbirds and turtles.

Photo: Sandringham Lagoon, with Persicaria attenuata vegetation - provided by Catchment Solutions.

A fishway has been constructed at the lower end of the lagoon to improve upstream and downstream connectivity of aquatic species. Due to the abundance of different species, the Lagoon is also used for aquatic ecosystem monitoring programs.

Photo: Fishway at the lower end of Sandringham Lagoon- provided by Reef Catchments (NRM) group for the Mackay Whitsunday Isaac region.

More information on the Sandringham Bay Fish Community Survey can be found HERE.

Photos: Fish Monitoring within Sandringham Lagoon - provided by Catchment Solutions.

Geology of Sandringham Catchment

The undulating landscape surrounding the lagoon and creek system contains areas of hard geologies such as mixed volcanics and granitoids. These areas generally have low permeability and influence water flow and channel formation, with high surface water runoff. Some of the metamorphosed rock provides for local groundwater recharge through fractures.

Diagram illustrating Fractured Geology - provided by WetlandInfo.

The lagoon and creek are situated within the lower elevations of the landscape which mostly consist of alluvium and other unconsolidated sediments. Alluvial geologies store and release water like a sponge and are made up of permeable silts, sands and gravels that absorb and hold water, and recharge groundwater systems.

Sandringham lagoon does not have a well defined upstream channel and is likely fed by the water from the upland fractured geologies which allows infiltration from local groundwater source.

Diagrams illustrating Wetland Soils - provided by WetlandInfo.

Modified Features of Sandringham Catchment

The Sandringham Lagoon, Creek and Bay areas have been modified to support sugar cane and cattle grazing, which are important to the local economy and community.

Some of the modifications include:

• Water canals were constructed for crop irrigation, which run from the main lagoon.
• A fishway was constructed downstream of the lagoon at Campbell’s Ridge Road which connects the lagoon to Sandringham Creek, and another rock ramp fishway was constructed in Sandringham Bay Conservation Park.
• Detention ponds were added to the creek system between the lagoon and the bay to provide greater connectivity for fish migration, slow the velocity of water moving down the creek, and reduce sediment and nutrient runoff from the surrounding sugar cane farms.
• The majority of riparian vegetation has been cleared for sugarcane farming, with the most extensive portions of riparian vegetation located around the lagoon and towards the bay.

Photo: Sandringham Works Locations - provided by Catchment Solutions.

Photo: Rock Ramp Fishway within Sandringham Restoration Site - provided by Reef Catchments (NRM) group for the Mackay Whitsunday Isaac region.

Modified Features of Sandringham Catchment

Important infrastructure like roads, railways, and creek crossings can also alter the flow of water throughout the system. Levy banks have been constructed along the rail line to the south of the lagoon, continuing along Balberra Road, redirecting flood waters into Sandringham Creek.

Diagram illustrating Levee influence on water flows - provided by WetlandInfo.

There are also many bores, particularly in the north of the catchment. The bores extract water mostly for irrigation and some have slightly brackish water which may indicate limited connection to the freshwater Sandringham lagoon.

Significant restoration works have occurred where large amounts of pest plants were removed from the Lagoon. This has consisted mainly of water hyacinth, water lettuce and hymenachne. Trees were planted along the riparian zone with a high success rate. By removing the weeds, water quality has improved significantly, and the number of fish and waterbirds that use the lagoon has increased.

To see the changes in Vegetation over time, Click Here and use the sliders.

More information on the Water Quality and Fish Rehabilitation projects within the Mackay / Whitsunday Region can be found HERE.

Photos: Restoration works within Sandringham Lagoon - provided by Catchment Solutions.

Hydrology of Sandringham Catchment

The Sandringham catchment area can be split into three distinct areas:

• The Sandringham Lagoon.
• The Sandringham Creek, and,
• The Sandringham Bay Conservation Park.

The Sandringham Lagoon is a lacustrine wetland in which the water source is thought to come from a natural underground spring. This spring is thought to be the main source of base flow and critical to the lagoon’s existence.

The water within the lagoon is also recharged from the surrounding fractured geology within the ridges above the lagoon and from its sandy alluvial base below. With constrictions at either end of the lagoon, it acts as a sinkhole to the incoming groundwater and remains a permanent water source. The groundwater from the underground spring is fresh and of high quality.

The Lagoon reaches depths of up to 2 metres near the lower end. The height of the water levels can drop during dryer conditions but is never empty. Much of the surrounding lower landscape to the lagoon is flat and prone to flooding, which can contribute to additional overland flow during peak rainfall events.

Photo: Sandringham Lagoon - provided by Reef Catchments (NRM) group for the Mackay Whitsunday Isaac region.

Hydrology of Sandringham Catchment

The Sandringham catchment area can be split into three distinct areas:

• Sandringham Lagoon
• Sandringham Creek, and,
• Sandringham Bay Conservation Park.

Sandringham Lagoon is a lacustrine wetland that appears to be connected to a natural underground spring. This spring is thought to be the main water source and critical to the lagoon’s existence, and is fed from underground fractured geologies in the upland areas.

The lagoon is constricted at either end, where incoming groundwater is captured. The groundwater is fresh and of high quality.

The Lagoon is up to 2 metres in depth near the downstream end. The water levels can drop during dryer conditions but the lagoon is rarely empty. Much of the surrounding landscape to the lagoon is flat and prone to flooding, which can contribute to additional overland flow into the lagoon during rainfall events.

Hydrology of Sandringham Catchment

Sandringham Creek is a riverine system and is fairly shallow due to harder underlying bedrock which does not allow for deep channelling in the system.

The fishway at the downstream end of the lagoon can act as a restriction to the intermittent base flow and causes natural pooling during low flow events.

During high flow the water can break the banks. The area surrounding the creek is a natural floodplain. Levees have been constructed along the rail lines and roads to the south, redirecting flood waters into Sandringham Creek.

The creek is also tidally influenced and reaches as far west as the Bruce Highway.

Photo: Sandringham Creek - provided by Reef Catchments (NRM) group for the Mackay Whitsunday Isaac region.

Hydrology of Sandringham Catchment

Sandringham Bay Conservation Park is an estuarine wetland system and consists of multiple regional ecosystems recognised under the Matters of State Environmental Significance. For more information on MSES, Click Here.

It contains mangrove habitat which is significant to first nations culture. Crocodiles have also been spotted within the Sandringham Bay Conservation Park.

Photo: Ceriops Australis Mangrove habitat within Sandringham Bay - provided by Reef Catchments (NRM) group for the Mackay Whitsunday Isaac region.

Due to high ecological diversity, Sandringham Bay is identified under the Directory of Important Wetlands in Australia (DOIW). For more information on DOIW, Click Here.

More information on the Water Quality Improvement Plan for Sandringham Bay can be found HERE.

Photos: Sandringham Bay Conservation Park - provided by Reef Catchments (NRM) group for the Mackay Whitsunday Isaac region.

Hydrology of Sandringham Catchment

The wetlands located in and around the Sandringham Bay Conservation Park provide many important functions due to the unique soils and water holding capacity. Wetlands are the boundary between two different ecosystems, dry and wet, which means they have a unique role in nutrient exchange and water supply to the surrounding lands, as well as providing habitat, food and shelter to many different plants and animals.

Photo: Birds of Sandringham Bay - provided by Reef Catchments (NRM) group for the Mackay Whitsunday Isaac region.

Some of the wetland habitat is also an important part of many grazing properties. Most wetlands within Queensland are on privately owned or managed freehold or leasehold lands, many of which are grazing enterprises.

Photos: Wetland grazing - provided by Catchment Solutions, monitoring group for the Mackay Whitsunday Isaac region.

Improvements and adoption of best management practices on these important ecosystems can enhance ecosystem services and improve grazing systems - The ‘High priority coastal and island restoration for the protection of significant ecological communities and species project’ is funded by the Australian and Queensland Governments. Significant restoration has been implemented to designated areas of the wetlands, which includes a new fish rock ramp for greater connectivity during high tides. More information about the Sandringham Wetland Restoration Project can be found HERE.

Photo: Fishway Rock Ramp - provided by Catchment Solutions, monitoring group for the Mackay Whitsunday Isaac region.

Reef Catchments also showcase some of the project outcomes for the Sandringham Wetlands, which can be found HERE.

More information on the Queensland Wetlands Management Strategy can be found HERE.

Photo: Sandringham Bay and surrounding wetland areas - provided by Reef Catchments (NRM) group for the Mackay Whitsunday Isaac region.

Summary

Sandringham Lagoon is considered a unique biodiversity hotspot for the Lower Sandy Creek Subcatchment. It's story showcases how natural and modified features within the landscape can impact how water flows.

Ongoing management and monitoring of this catchment ensures that the values within the lagoon, creek and bay are protected and that the downstream processes of these differing systems support the values of the GBR.

Knowing how the catchment functions is also important for future planning, including climate resilience. With this knowledge, better decisions can be made about how to manage these vital wetland ecosystems.

Photo: Sandringham Lagoon - provided by Catchment Solutions, monitoring group for the Mackay Whitsunday Isaac region.

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Last updated: 10 July 2023