Transcript

Magnetic Island Catchment Story

This catchment story is part of a series prepared for the catchments of Queensland.

Table of contents

1. Understanding how water flows in the catchment
2. How to view this map journal
3. Map journal for the Magnetic Island catchment—water movement
4. Magnetic Island catchment story
5. Values of the catchment—key features
6. Values of the catchment—economic
7. Values of the catchment—environmental and social
8. Natural features—geology and topography
9. Natural features—rainfall
10. Natural features—vegetation
11. Modified features—infrastructure, dams, weirs and bores
12. Modified features—sediment
13. Water quality
14. Water flow
15. The main areas
16. Rollingstone Bay
17. West Coast
18. Picnic Bay
19. Nelly Bay
20. Arcadia
21. Radical Bay
22. Horseshoe Bay
23. Five Beach Bay
24. Conclusion
25. Acknowledgments
26. Data source, links and extra information

Main image. Waterfall on Endeavour Creek - provided by Alana Lorimer.

Understanding how water flows in the catchment

To effectively manage a catchment it is important to have a collective understanding of how the catchment works. This map journal gathers information from experts and other data sources to provide that understanding.

The information was gathered using the walking the landscape process*, where experts systematically worked through a catchment in a facilitated workshop, to incorporate diverse knowledge on the landscape features and processes, both natural and human. It focused on water flow and the key factors that affect water movement.

This map journal was prepared by the Queensland Wetlands Program in the Queensland Department of Environment and Science, in collaboration with local partners.

Altered flow path of Peterson Creek following heavy rainfall - provided by Tony O'Malley.

*The ‘walking the landscape’ process involves local stakeholders systematically working through a catchment in a facilitated workshop, to incorporate diverse knowledge on the landscape (Department of Environment and Heritage Protection 2012) - see links at the end of this map journal for further information.

How to view this map journal

This map journal is best viewed in Chrome or Firefox, not Explorer.

Main image. Looking towards Horseshoe Bay from the forts (WWII fortifications and infrastructure) - provided by Alana Lorimer.

Map journal for the Magnetic Island catchment—water movement

This map journal describes the location, extent and values of the Magnetic Island catchment*. It demonstrates the key features which influence water flow, including geology, topography, rainfall and runoff, natural features, human modifications and land uses.

Knowing how water moves in the landscape is fundamental to sustainably managing the catchment and the services it provides.

Water flow through rock scree, Arthur Bay - provided by Hugh Wallace Smith.

Huntingfield Bay - provided by Alana Lorimer.

Main image. Isolated pool on Endeavour Creek - provided by John Gunn.

*The use of the terms 'catchment', 'sub-catchment', 'basin' and 'sub-basin' are sometimes used interchangeably. In this map journal the term 'catchment' has been used.

Magnetic Island catchment story

Magnetic Island is located in North Queensland and is part of the NQ Dry Tropics Natural Resource Management (NRM) region. The Magnetic Island catchment falls within the Townsville City Council area.

The catchment covers approximately 51 square kilometres (click for animation).

The island has many small waterways including Retreat, Duck, Frasers, Ned Lee, Butlers, Hoyer, Scrub Fowl, Gustav, Petersen, Alma, Gorge and Endeavour creeks Chinaman Gully. All waterways (click for animation) flow to the Great Barrier Reef (GBR) via a number of embayments.

Mangroves growing along creek on the west coast - provided by Brian Johnson..

The catchment is mostly conservation and natural environments*, including the Magnetic Island National Park. The island is also part of the Great Barrier Reef World Heritage Area (WHA), which includes 2,500 reefs and more than 900 islands, ranging from small sandy cays to larger vegetated cays to continental islands such as Magnetic Island.**

The GBR is also a marine park (GBRMP) and there are several green zones directly adjacent to the island (Marine National Parks).

Horseshoe Bay beach - provided by John Gunn.

There is a drop-down legend for most maps and it can be accessed by clicking on 'LEGEND' at the top right of the map. On this map you can use the drop down legend for the land use.

There are also 'pop-ups' for most mapping features - simply click on the mapping of interest for more information.

Main image. Granite boulders, Alma Bay - provided by John Gunn.

*'This class includes land that has a relatively low level of human intervention. The land may be formally reserved by government for conservation purposes, or conserved through other legal or administrative arrangements. Areas may have multiple uses, but nature conservation is the prime use. Some land may be unused as a result of a deliberate decision of the government or landowner, or due to circumstance', taken from Australian Land Use Management Classification (Department of Agriculture and Water Resources 2010) . See links at the end of this map journal for further information.

**Great Barrier Reef World Heritage Listing (UNESCO 2019) - see links at the end of this map journal for further information.

Values of the catchment—key features

Key features of the Magnetic Island catchment include:

• The island is mostly granite, together with colluvium, alluvium, sand ridges (high dunes and swales) and marine deposits (estuaries).
• There are areas of mafite / felsite in the north-west at West and Liver points.
• Usually, the island experiences annual wet and dry seasons, with 80% of the area’s rainfall during the wet season between November and March.
• The hydrological seasonality associated with these wet and dry season flow conditions are important to the ecological character, function and associated values of aquatic ecosystems.
• Most creeks hold water seasonally in isolated pools, with Gustav Creek typically holding more water than other waterways on the island.
• Most creek mouths are intermittently closed and open lagoons (ICOLs), which are typically opened to estuarine waters following heavy rainfall in the wet season.
• Generally, upper parts have fast flow through straight channels in the hard granite, with some fracturing, dolerite dykes, local groundwater recharge and seeps and hanging valleys.
• Several rocks screes where surface water enters groundwater systems, including Nelly and Horseshoe bays. 
• Land use is mostly conservation and natural areas, together with residential and associated services, waste treatment and disposal and other minor land uses.
• Natural hydrology has been substantially modified in Nelly and Horseshoe bays.
• Protected areas include the GBR WHA, Magnetic Island National Park, conservation parks and nature refuges, together with the adjacent Great Barrier Reef Marine Park (GBRMP) and Cleveland Bay—Magnetic Island Dugong Protection Area.
• Large areas of estuarine wetland, mostly along the west coast, together with riverine and palustrine wetlands and areas of ‘contains wetlands’*.
• The island supports many important vegetation communities such as vine thickets, mangroves, saltmarshes and seagrasses, and species such as butterflies, frogs, shorebirds and marine turtles.
• Treated drinking water is piped from Pallarenda on the mainland to Bolger Bay pump station and balance tank, from where it is distributed to other reservoirs on the island and ultimately consumers**.
• Water is also sourced from bores and water recycling facilities at Picnic*** and Horseshoe^ bays, mostly for irrigation.
• There is a sewage treatment plant at Cockle Bay with a smaller treatment system at Horseshoe Bay and many areas using septic or composting systems.

Petersen Creek mouth ICOL, Geoffrey Bay - provided by John Gunn.

Main image. Wetland, Horseshoe Bay - provided by Alana Lorimer.

*Areas mapped as ’contains wetlands’ typically include many small wetlands, which are too small to map individually.

See links at the end of this map journal for further information on the following:

**Magnetic Island Water Recycling (Citiwater Townsville 2002)

***Magnetic Island Water Recycling Facility (Townsville City Council undated)

^Horseshoe Bay Water Recycling Facility (Townsville City Council undated)

Values of the catchment—economic

Magnetic Island supports several different land uses*, mostly conservation and natural areas, together with residential and associated services, waste treatment and disposal and other minor land uses.

Nelly Bay - provided by Hugh Wallace Smith.

Tourism is important to the local economy. The island is popular with day visitors from Townsville, backpackers and other international and national travellers. The marina at Nelly Bay Harbour provides easy access by ferry from nearby Townsville.

Nelly Bay - provided by Maria Zann.

*Australian Land Use Management Classification (Department of Agriculture and Water Resources 2010) - see links at the end of this map journal for further information. Noting that residential areas on Magnetic island include the following three types. See vegetation slide for extent of clearing and regrowth in these residential areas.

• Urban residential (land with houses, flats, hotels and so on within urban areas)
• Rural residential without agriculture (rural allotments with no agricultural activity present (may have backyard or domestic garden areas, or livestock as pets))
• Remote communities (area with a small, isolated community, generally less than 20 residences or buildings (without the facilities associated with even small towns) that lies within an area defined by the Australian Standard Geographical Classification – Remoteness Areas (ASGC-RA) system as remote or very remote)

Values of the catchment—environmental and social

Magnetic Island provides important habitat for many marine, estuarine, freshwater and terrestrial species.

Alma Creek interpretative signage - provided by John Gunn.

The Magnetic Island catchment includes large areas protected by the state, and is part of the GBR WHA. The island provides for recreational activities such as bush walking, bird watching, boating, fishing, swimming and snorkelling. These activities not only provide substantial social and health benefits, but are also very important for tourism.

WWII fortifications, looking towards Cape Cleveland (left) and Mount Elliott (right) - provided by Alana Lorimer.

The wetlands and creeks of the catchment provide habitat for many important species.

Freshwater wetlands support a wide range of flora and fauna including aquatic plants, invertebrates, frogs, fish and birds. Gustav Creek holds more water and typically supports more freshwater fish than other parts of the island. Seasonal frog habitat is provided by the sand dune systems on the west coast.

Estuarine wetlands support a wide range of flora and fauna including many important plants (mangrove, saltmarsh and seagrass), shorebirds, marine turtles, marine mammals and fisheries species. These systems are also adjacent to extensive sandy beach and coral reef ecosystems. Shorebirds feed and roost along the western side of the island, and also in several bays on the east coast such as Geoffrey Bay.

Mangroves growing along the west coast - provided by Brian Johnson.

Information about the different types of wetlands shown in this mapping is provided here.

Many of the species in the catchment have lifecycles with connections to the GBR. The GBR is a marine park and world heritage-listed, and is also listed on the Directory of Important Wetlands Australia.

The catchment also includes several nature refuges, and is adjacent to a Dugong Protection Area.

Turbinaria reniformis coral - provided by Maria Zann.

Cascade and meandering creek, Cockle Bay - provided by Maria Zann.

Main image. Swimming enclosure, Horseshoe Bay - provided by Alana Lorimer.

Natural features—geology and topography

Several different rock types combine to make up the geology of Magnetic Island.

Granite ridge, looking from the west coast - provided by Hugh Wallace Smith.

The island is mostly granite. The granite is 'fractured' with dolerite dykes (volcanic basalt) with straight creek lines forming in these hard geologies.

Basalt dyke, Arthur Bay - provided by Charlie McColl.

The granites intruded through older volcanic geologies during the early Permian intrusions (approximately 286 to 258 million years ago) with the older volcanic geologies formed during the late Carboniferous period (approximately 320 to 286 million years ago).*

The change in geology, showing granite boulders (left) over the older layered and tilted volcanics (right) - provided by Charlie McColl.

Small areas of these older Julago Volcanics (mixed mafites and felsites) remain and are exposed along the north coast from West Point, around Rollingstone Bay and Liver Point to Huntingfield Bay.

Julago Volcanics, Liver Point - provided by Charlie McColl.

Different volcanic materials within the Julago Volcanics at Liver Point - provided by Charlie McColl.

Most of the colluvium, alluvium and sand is of granitic origin.** However, there are also high sand dunes, which have been formed over geological time frames by wind and wave action moving sand into high ridges. Marine deposits are associated with geologically more recent coastal processes.

High dunes, Endeavour Creek - provided by Hugh Wallace Smith.

Sandy sediments of Alma Bay - provided by Alana Lorimer.

Sandy sediments of Alma Bay - provided by Alana Lorimer.

Conceptual models for several of the catchment's geology types are provided below.

Main image. Granite boulders, Arthur Bay - provided by John Gunn.

*Rocks and Landscapes of the Townsville District (Trezise and Stephenson 1990) - see links at the end of this map journals for further information.

**Topography: Beaches and other Geomorphical Considerations (Hopley 1978) - see links at the end of this map journal for further information.

Natural features—rainfall

Magnetic Island usually experiences annual wet and dry seasons, with most of the rainfall typically between November and March (i.e. wet season).

The hydrological seasonality associated with these wet and dry season flow conditions are important to the ecological character, function and associated values of aquatic ecosystems. The dry season is also an important part of the functioning of the system.

Most creeks hold water seasonally in isolated pools, with Gustav Creek typically holding more water than other waterways on the island. Most creek mouths are ICOLs, which are typically opened to estuarine waters following heavy rainfall in the wet season.

Alma Creek dry channel - provided by John Gunn.

Main image. Storm rolling in over Alma Bay - provided by Alana Lorimer.

Natural features—vegetation

Vegetation affects how water flows through the catchment, and this process is affected by land use and management practices. Native vegetation slows water, retaining it longer in the landscape and recharging groundwater aquifers, and reducing the erosion potential and the loss of soil from the catchment.

Roughness conceptual model - provided by Department of Environment and Science.

Several different vegetation types combine to make up the original native (preclearing) vegetation of the Magnetic Island catchment.*

Small parts of the catchment have been cleared or partially-cleared for mostly residential areas and associated services. Some of the cleared vegetation has regrown** since initial clearing. 

Coastal vegetation, Geoffrey Bay - provided by John Gunn.

Explore the swipe map showing vegetation clearing over time, using either of the options below.***

• Interactive swipe app where you can zoom into areas and use the swipe bar (ESRI version)
• Interactive swipe app where you can use the swipe bar. Use the white slide bar at the bottom of the map for a comparison (HTML version)

These developments and activities change the shape of the landscape and can modify water flow patterns.

Looking across the densely vegetated island - provided by Alana Lorimer.

Main image. Mangroves - provided by Hugh Wallace Smith. 

*The Broad Vegetation Groups (BVG 5M) shown in the above mapping include many different Regional Ecosystem (RE) types. This mapping shows the preclearing and remnant  (including regrowth) REs. Regional Ecosystems are vegetation communities in a bioregion that are consistently associated with a particular combination of geology, landform and soil.

**Smaller areas of regrowth are not shown in this mapping. This dataset was prepared to support certain category C additions to the Regulated Vegetation Management Map under the Vegetation Management (Reinstatement) and Other Legislation Amendment Bill 2016. This dataset is described as: The 2013 areas of non-remnant native woody vegetation that have not been cleared between 1988 and 2014 that are homogenous for at least 0.5 hectare and occur in clumps of at least 2 hectares in coastal regions and 5 hectares elsewhere.

***This application takes time to load.

Modified features—infrastructure, dams, weirs and bores

There is limited infrastructure on Magnetic Island*, however residential and commercial development has modified natural hydrology in some areas, particularly Nelly and Horseshoe bays. Modifications to channels, such as straightening and diversions, can increase flow rates and erosion.

Nelly Bay Harbour - provided by Maria Zann.

Important infrastructure such as the marina, roads and creek crossings can create barriers and impermeable surfaces that redirect water through single points or culverts, leading to channeling of water in some parts of the catchment. The road along the west coast has modified natural hydrology.

West coast road - provided by Hugh Wallace Smith.

Coastal development has modified flow and estuarine connectivity in Gustav Creek and the unnamed creek to the east. Some sections of Gustav Creek are deeply incised and the bank has been stabilised adjacent to some residential areas. The Sooning Street causeway has raised the base level of the creek bed, which can influence flow.

The hydrology of the lower Horseshoe Bay subcatchment is complex and modifications include channel diversions, hardening of the catchment by residential and commercial development, weirs, infilling, crossings, extraction and stormwater infrastructure. The Endeavour Creek bed has been lowered and the system has changed from a series of freshwater lagoons to estuarine. This subcatchment has the most extensive freshwater wetlands on the island.

Horseshoe Bay development - provided by Hugh Wallace Smith.

Erosive soils along creek line, Horseshoe Bay area - provided by Alana Lorimer.

Roads and permeable surfaces conceptual models provided by Department of Environment and Science

Dams and weirs also modify natural water flow patterns. They can hold water that would otherwise flow straight into the stream network, and influence tidal movement. There are small dams and/or weirs along the west coast and in the Horseshoe Bay area.

Treated drinking water is piped from Pallarenda on the mainland to Bolger Bay pump station and balance tank, from where it is distributed to other reservoirs on the island and ultimately consumers. Most of the effluent is re-used on the island. Re-cycled water is applied to sports fields, dry tropics rainforest, golf course, capped landfill, transfer station, and wastewater treatment plant sites. Residents have use of private bores for irrigation of their properties, but council typically use potable water on esplanades and high public use areas. There are many bores** across the island, which extract water and can influence groundwater systems.

Infrastructure can also affect fish passage through the catchment.

Olympus Crescent crossing of Alma Creek - provided by John Gunn.

Main image. Pedestrian crossing, Alma Creek mouth - provided by Tony O'Malley.

*Townsville City Council provides access to asset infrastructure, contours, planning scheme zoning, overlay maps including storm tide, etc. - see links at the end of this map journal for further information.

**Taken from database storing registered water bore data from private water bores and Queensland Government groundwater investigation and monitoring bores.

Modified features—sediment

Most of Magnetic Island is undeveloped and protected by remnant (original) native vegetation.

In more developed areas, increases in the volume and speed of runoff, and disturbed vegetation through activities such as construction, can increase erosion in the landscape and stream channels. This can result in sediment being carried downstream and reduced water quality. The construction stage of a development typically generates more sediment in runoff than more mature stages of a development.

Coastal erosion can also be associated with wave action, particularly cyclones.

The suspended sediment of most risk to the GBR is the fine fraction. Fine sediment

• contains most of the nitrogen and phosphorus content (and other potential contaminants such as metals),
• travels widely in flood plumes rather than all depositing near the river mouth, and
• substantially reduces light when in suspension.

Furthermore, the impacts of suspended sediment contributes to the cumulative impacts of other stressors (e.g. freshwater flood plumes, elevated nutrients, impacts from cyclones, increasing sea surface temperatures) to increase the overall impact on organisms of the GBR.*

Cockle Bay in the early 1900s with main image taken at the same location in 2016, illustrating increased mangrove growth - provided by Charlie McColl.

Main image. Cockle Bay, 2016 - provided by Charlie McColl.

*Great Barrier Reef Catchment Loads Modelling Program (Queensland Government, 2017); Reef 2050 Water Quality Improvement Plan 2017-2022. Queensland Government (2018) ; Reef 2050 Water Quality Improvement Plan - Report cards (Queensland Government (2017) - see links at the end of this map journal for further information.

Water Quality

Water quality is influenced by diffuse runoff and point source inputs. Runoff is from mostly residential land uses but also recreational (e.g. golf course) and commercial (e.g. marina services) areas.

Diffuse runoff includes on-site sewage facilities (e.g. septic tanks) and stormwater discharges, particularly from low permeability surfaces in built-up areas. Many residential areas use on-site sewage facilities such as septic tanks or composting systems. The concentration of potential contaminants in the stormwater discharge depends on the land use of the area.

Point source inputs include the sewage treatment plant (STP) at Cockle Bay (Picnic Bay STP) together with the smaller treatment system at Horseshoe Bay.

Main image. Nelly Bay - provided by Alana Lorimer.

Water flow

Water flows across the landscape into the small waterways of the island (click for animation)*.

Petersen Falls - provided by Tony O'Malley.

The remaining water either sinks into the ground where it supports a variety of terrestrial and groundwater dependent ecosystems or is used for other purposes. Unconsolidated sediments and several rock screes allow for surface water to move in and out of groundwater systems. Boulders near creek mouth, Radical Bay - provided by John Gunn.

The small channels and gullies of the island combine to form more defined waterways that flow to the GBR. In some areas, they pass through unconsolidated sediments which can store and release water.

Boulders near creek mouth, Radical Bay - provided by John Gunn.

Main image. Isolated pool on Endeavour Creek, Horseshoe Bay - provided by John Gunn.

*Please note this application takes time to load.

The main areas

A 'catchment' is an area with a natural boundary (for example ridges, hills or mountains) where all surface water drains to a common channel to form rivers or creeks.*

The Magnetic Island catchment is listed as a single catchment but consists of several distinct areas which have similar characteristics:

1. Rollingstone Bay (Rollingstone Bay, Liver Point)
2. West Coast (Retreat, Duck, Ned Lee and Frasers creeks, Chinaman Gully, Young, Bolger and Cockle bays, West Point)
3. Picnic Bay (Butlers Creek, Picnic Bay, Hawkings Point, Nobby Head, Sailors Rock)
4. Nelly Bay (Gustav Creek, Bright Point, Nelly and Rocky bays, Presto Breakwater, Nelly Bay Harbour)
5. Arcadia (Petersen Creek, Geoffrey and Alma bays, Bremner Point)
6. Radical Bay (Balding, Radical, Gowrie, Florence, Arthur and Whitfield bays)
7. Horseshoe Bay (Gorge and Endeavour creeks, Horseshoe Bay, White Lady Rock)
8. Five Beach Bay (Five Beach, Huntingfield, Wilson, Joyce, Norris, Maud and  Lovers bays, White Rock)

*Definition sourced from the City of Gold Coast website - see links at the end of this map journal.

Rollingstone Bay

• The Rollingstone Bay subcatchment is mostly granite, together with the older layered and tilted Julago Volcanics (mixed mafite and felsite)
• Fast flow through straight channels in the hard granite, with bedrock-controlled channels that flow into Rollingstone Bay
• Land use is all conservation and natural areas, including the GBR WHA and Magnetic Island National Park, together with the adjacent Cleveland Bay-Magnetic Island Dugong Protection Area and GBRMP
• Unique plant species and communities on skeletal soils

Main image. Julago Volcanics at Liver Point - provided by Charlie McColl.

*Areas mapped as ’contains wetlands’ typically include many small wetlands, which are too small to map individually.

West Coast

• The West Coast subcatchment is mostly granite, with large areas of colluvium, sand ridges and marine deposits (estuaries)
• Fast flow through straight channels in the hard granite
• Several hanging valleys associated with dykes, which feature springs, waterfalls, cascades, cloud forests and diverse vegetation such as blue gums (Eucalyptus tereticornis), hoop pines, wattles and grasses
• Well-developed sand dune systems, which were historically mined and now have surface expression of ‘free water’, which provides seasonal frog habitat
• Land use is mostly conservation and natural areas, together with residential and associated services, waste treatment and disposal and other minor land uses
• A channel was dredged through the coral for road base
• Protected areas include the GBR WHA, Magnetic Island National Park and Brolger Bay Conservation Park, together with Bolger Bay Nature Refuge and adjacent Cleveland Bay—Magnetic Island Dugong Protection Area and GBRMP
• Large areas of estuarine wetland, together with riverine and palustrine wetlands and areas of ‘contains wetlands’*
• Waterfalls, cascades and swimming holes in the lower parts
• Most creek mouths are ICOLs 
• Discharge area with lots of freshwater seeps into Bolger Bay
• Environmental values include mangroves, seagrass, coral, shorebirds and marine turtles
• Shorebirds feed along the western side of the island, including Pacific golden plovers, eastern curlews, grey tailed tattlers and whimbrels, and there is also important roosting habitat with whimbrels, curlews, golden plovers and various sandpipers roosting in the saltpans behind Retreat Creek
• Cockle Bay STP receives sewage from parts of Picnic Bay, Nelly Bay and Arcadia

Waterfall, Cockle Bay - provided by Maria Zann.

West coast road - provided by Hugh Wallace Smith.

Main image. West coast beach - provided by Hugh Wallace Smith.

*Areas mapped as ’contains wetlands’ typically include many small wetlands, which are too small to map individually.

Picnic Bay

• The Picnic Bay subcatchment is mostly granite, together with colluvium and sand ridges
• Fast flow off the hard granite into ephemeral creeks lower in the landscape
• Land use is mostly conservation and natural areas, together with residential and associated services (golf course) and other minor land uses
• Protected areas include the GBR WHA and Magnetic Island National Park, together with the adjacent Cleveland Bay—Magnetic Island Dugong Protection Area and GBRMP
• Environmental values include estuarine and riverine wetlands, coral reefs and seagrass

Hawkings Point, most southern point of the island between Picnic and Nelly bays - provided by Alana Lorimer.

Main image. Picnic Bay - provided by Alana Lorimer.

Nelly Bay

• The Nelly Bay subcatchment is mostly granite, together with colluvium, alluvium and sand ridges
• Fast flow through straight channels in the hard granite, into a near-permanent lower system with incised channels, rock bars, waterholes, lagoons and ICOL 
• The natural hydrology of Gustav Creek has been modified, resulting in altered flows, altered estuarine connectivity, sediment build-up and erosion, with activities to address this including bank stabilisation and periodic removal of sediment
• Large hanging valley with springs and unique flora including Alexander palms, and several landslips across the subcatchment
• Two main rock screes where surface water can move into groundwater systems
• Land use is mostly conservation and natural areas, together with residential and associated services, and other minor land uses 
• The marina development (Nelly Bay Harbour) includes a ferry terminal, together with urban residential and associated services
• Protected areas include the GBR WHA and Magnetic Island National Park, together with the adjacent Cleveland Bay—Magnetic Island Dugong Protection Area and GBRMP
• Environmental values include estuarine and riverine wetlands, coral reefs, seagrass and turtle nesting
• Gustav Creek typically holds more water and supports more freshwater fish than other waterways on the island

Nelly Bay shoreline, looking north towards the Nelly Bay Harbour - provided by John Gunn.

Gustav Creek - provided by John Gunn.

Nelly Bay shoreline, looking north towards the Nelly Bay Harbour - provided by John Gunn.

Arcadia

• The Arcadia subcatchment is mostly granite, together with colluvium and sand ridges
• Fast flow off the hard granite into ephemeral creeks lower in the landscape
• Land use is mostly conservation and natural areas, together with residential and associated services
• Protected areas include the GBR WHA and Magnetic Island National Park, together with the adjacent Cleveland Bay—Magnetic Island Dugong Protection Area and GBRMP (green zones)
• Environmental values include estuarine and riverine wetlands, vine thickets, seagrass, coral reefs, turtle nesting, shorebirds and other birds, and flying foxes
• Shorebirds feed and roost along Geoffrey Bay, including common sandpipers, whimbrels and eastern curlews.
• Parts of Arcadia are sewered to Cockle Bay STP, however most of this subcatchment uses septic systems

 Granite boulders, Alma Creek - provided by John Gunn.

Petersen Creek adjacent to residential area of Arcadia - provided by Townsville City Council.

Crossing of Alma Creek - provided by Tony O'Malley.

Main image. Alma Bay looking north towards Geoffrey Bay - provided by John Gunn.

*Areas mapped as ’contains wetlands’ typically include many small wetlands, which are too small to map individually.

Radical Bay

• The Radical Bay subcatchment is mostly granite, together with colluvium and sand ridges
• Fast flow off the hard granite into short ephemeral creeks lower in the landscape
• Land use is mostly conservation and natural areas, together with services 
• Protected areas include the GBR WHA and Magnetic Island National Park, together with the adjacent Cleveland Bay—Magnetic Island Dugong Protection Area and GBRMP (green zones)
• Environmental values include estuarine wetlands (mangroves), areas of ‘contains wetlands’*, vine thickets, coral reefs and species such as the Townsville lily

Radical Bay - provided by John Gunn.

Balding Bay - provided by Alana Lorimer.

Florence Bay - provided by Alana Lorimer.

Main image. Radical Bay boulders - provided by John Gunn.

 *Areas mapped as ’contains wetlands’ typically include many small wetlands, which are too small to map individually.

Horseshoe Bay

• The Horseshoe Bay subcatchment is mostly granite, together with colluvium, sand ridges and marine deposits
• Fast flow off the hard granite into a flat landscape with complex hydrology that has been modified
• The lower parts are ephemeral but complex and include channel diversions, hardening of the catchment, weirs, infilling, crossings, extraction and stormwater inputs into a landscape with the most extensive wetlands on the island
• The Endeavour Creek bed has been lowered and the system has changed from a series of freshwater lagoons to estuarine, although the mouth closes from time to time (i.e. ICOL)
• The (unnamed) eastern creek has been modified including altered flows through residential areas in the upper parts, and infilling, weeds, hardening-up of the banks, and weirs in the lower parts
• The subcatchment funnels through boulder scree where surface water enters groundwater systems
• Water can break through the bank/shoreline seasonally
• High sand dune systems 
• Hanging valleys, rock screes and springs at higher elevations
• Land use is mostly conservation and natural areas, together with residential and associated services
• Protected areas include the GBR WHA and Magnetic Island National Park, together with Horseshoe Bay Lagoon Conservation Park, nature refuges (Endeavour Creek and Horseshoe Bay) and the adjacent Cleveland Bay—Magnetic Island Dugong Protection Area and GBRMP
• Environmental values include estuarine (mangroves), palustrine and riverine wetlands, areas of ‘contains wetlands’*, coral reefs, seagrass and species such as dugongs, flatback turtles and blue tiger butterflies

Horseshoe Bay beach - provided by Maria Zann.

Endeavour creek mouth, Horseshoe Bay - provided by Alana Lorimer.

Isolated pool, Endeavour Creek - provided by John Gunn.

High dunes, Endeavour Creek - provided by Hugh Wallace Smith.

Main image. Wetland recreation area, Horseshoe Bay - provided by Alana Lorimer.

Five Beach Bay

The Five Beach Bay subcatchment is mostly granite, together with Julago Volcanics (mixed mafite and felsite).

• Fast flow through straight channels in the hard granite, with short ephemeral creeks lower in the landscape 
• Huntingfield Bay is located at the interface of the granite and Julago volcanics and there is a creek running along the interface, together with waterfalls, springs, waterholes and steep dunes
• Land use is all conservation and natural areas, including the GBR WHA and Magnetic Island National Park, together with the adjacent Cleveland Bay—Magnetic Island Dugong Protection Area and GBRMP (green zone)
• Large areas of estuarine wetland, mostly along the west coast, together with riverine and palustrine wetlands and areas of ‘contains wetlands’*

Hoop pines growing on the volcanics - provided by Charlie McColl.

Wattle and hoop pines growing on the granite - provided by Charlie McColl.

Huntingfield Bay, looking up the creek line running along the granite-volcanic interface - provided by Charlie McColl.

*Areas mapped as ’contains wetlands’ typically include many small wetlands, which are too small to map individually.

Conclusion

The Magnetic Island catchment shows how natural and modified features within the landscape impact on how water flows. These issues need to be managed to ensure that the significant natural (and social) values of the catchment are protected, and to minimise impacts on the multitude of values within the catchment and downstream in the GBR, while providing for residential, water supply, farming and other important land uses of the catchment.

Knowing how the catchment functions is also important for future planning, including climate resilience. With this knowledge, we can make better decisions about how we manage this vital area.

Main image. Huntingfield Bay - provided by Alana Lorimer.

Acknowledgments

Developed by the Queensland Wetlands Program in the Department of Environment and Science in partnership with the Dry Tropics Partnership for Healthy Waters and other local partners:

Townsville City Council

Department of Natural Resources, Mines and Energy

Great Barrier Reef Marine Park Authority

Magnetic Island Nature Care Association

NQ Dry Tropics

Office of the Great Barrier Reef

This resource should be cited as: Walking the Landscape – Magnetic Island Catchment Story v1.0 (2010), presentation, Department of Environment and Science, Queensland.

Images provided by John Gunn, Brian Johnson, Alana Lorimer, Charlie McColl, Tony O'Malley, Hugh Wallace Smith, Townsville City Council, Maria Zann.

The Queensland Wetlands Program supports projects and activities that result in long-term benefits to the sustainable management, wise use and protection of wetlands in Queensland. The tools developed by the Program help wetlands landholders, managers and decision makers in government and industry.

Contact wetlands@des.qld.gov.au or visit https://wetlandinfo.des.qld.gov.au

Disclaimer

This map journal has been prepared with all due diligence and care, based on the best available information at the time of publication. The department holds no responsibility for any errors or omissions within the document. Any decisions made by other parties based on this document are solely the responsibility of those parties. Information contained in this education module is from a number of sources and, as such, does not necessarily represent government or departmental policy.

Data source, links and extra information

Software Used

ArcGIS for Desktop | ArcGIS Online | Story Map Journal| Story Map Series |

Some of the information used to put together this Map Journal can be viewed on the QLD Globe.

Queensland Globe allows you to view and explore Queensland spatial data and imagery. You can also download a cadastral SmartMap or purchase and download a current titles search.

More information about the layers used can be found here: Source Data Table

Flooding Information

Townsville City Council

Other References

City of Gold Coast (2021) About water catchments. [webpage] Accessed 25 August 2021

Department of Agriculture and Water Resources (2010) Australian Land Use Management Classification [webpage] Accessed 11 March 2019

Department of Environment and Heritage Protection (2012) Walking the Landscape—A Whole-of-system Framework for Understanding and Mapping Environmental Processes and Values, Queensland Wetlands Program, Queensland Government, Brisbane

Hopley, D. (1978) Topography: Beaches and other Geomorphical Considerations. Report for North Barrier Holdings Limited (Magnetic Keys Report, Nelly Bay, Bright Point Impact Assessment Study). Sir George Fisher Centre for Tropical Marine Studies, James Cook University of North Queensland.

Queensland Government (2016) Declared Fish Habitat Area Plans [webpage] Accessed 11 March 2019

Queensland Government (2016) Water Regulation 2016, Current as at 1 July 2018 [webpage] Accessed 11 March 2019

Queensland Government (2017) Key Resource Areas in Queensland [webpage] Accessed 11 March 2019

Queensland Government (2018) Great Barrier Reef Catchment Loads Modelling Program [webpage] Accessed 11 March 2019

Queensland Government (2018) Reef 2050 Water Quality Improvement Plan 2017-2022, State of Queensland, Brisbane

Queensland Government (2018) Reef 2050 Water Quality Improvement Plan - Report Cards [webpage] Accessed 11 March 2019

Queensland Government (2018) Water Quality Information Portal [webpage] Accessed 11 March 2019

Trezise, D.L. and Stephenson P.J. (1990) Rocks and Landscapes of the Townsville District, Department of Resource Industries, Brisbane

UNESCO (2019) Great Barrier Reef World Heritage Listing [webpage] Accessed 14 March 2019

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Last updated: 25 August 2021