Burdekin Delta

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Subcatchments

Smaller subcatchments within the Burdekin Delta Catchment include:

Vegetation

Riparian Habitat

iTRARC analysis of Riparian Habitat indicates that this subcatchment has undergone a large decrease in the condition of its riparian zones. It has changed from good (B+) to poor (C) condition as a result of floodplain and riparian clearing. The field surveys for this catchment also report poor condition as well, with some limited regeneration and a high amount of weediness.

iTRARC Scores

Catchment Class 4 A
Maximum iTRARC Score 20 (A+)
1970s Score 12 (B+)
2004 Score 3 (C)
Reduction in Ecosystem Services Very Large
Increase in Potential for Erosion Small
Reasons for Change in Score
  • Clearing in the upper catchment
  • Increased gaps in headwater streams
  • Floodplain clearing including the removal of forest and closed forest
  • Floodplain bare soil

TRARC (field survey) scores

Survey SiteScoreRegenerationWeeds
Crooked Lagoon [#1]56.3 (C)2 (B)2 spp: 20% cover (C)
Crooked Lagoon [#2]43.7 (D)0 (D)1 sp: 100% cover (D)
Kellys Lagoon48.3 (D)2 (B)1 sp: 70% cover (D)
Payards Lagoon52.7 (C)1 (C)1 sp: 100% cover (D)
Average 50.3 (C)

Reference:Assessing the condition of Riparian Vegetation in the Burdekin catchment

Wetlands

The Burdekin Delta contains perhaps the greatest concentration of wetland habitat in the entire catchment. The conservation values of the area include wetlands listed in the Directory of Important Wetlands in Australia, and as part of Bowling Green Bay National Park and Ramsar site. More is known of the creeks and wetlands on the left (northern) bank than on the right (southern) bank. Because of the intensive urban and agricultural land uses, many of the creeks and wetlands have been highly modified from their original state. Modified hydrology, loss of fish passage and riparian vegetation, and domination by aquatic weeds make many of the wetlands of poor quality (BBIFMAC 1999, Tait and Perna 2001). However, some retain significant values and recent rehabilitation efforts show that these systems can be healthy and productive ecological systems. This area is a high priority for such investments. Most wetland rehabilitation effort to date has been focused on Sheep Station Creek where many large lagoons have been cleared of dense mats of water hyacinth that had invaded their surface. This resulted in a significant improvement to water quality and increases in fish diversity as well as aesthetic and recreational benefits (see Perna 2003, 2004, Perna and Burrows 2005).

The Burdekin Falls Dam (also called Lake Dalrymple) fills with turbid water during high flow storm events and the fine colloids amongst this material does not settle sufficiently for the water to clarify to any meaningful degree (Griffiths and Faithful 1996, Burrows and Faithful 2003, Butler 2006, Burrows and Butler 2007). This turbid water is released downstream for irrigation purposes, rendering the lower Burdekin River turbid, as well as the many delta distributary streams (3,4,5,6,8 from above with 7 providing an example of an exception) into which this water is pumped for irrigation delivery. The wetlands and watercourses that receive this water had naturally relatively clear water, but are now much more turbid, creating a significant departure from the natural situation. This effect is strongest for the lower Burdekin River itself, but for parts of the other wetlands in this subdivision, the effect is sometimes reduced (eg, the turbidity declines towards the bottom end of Sheep Station Creek), hence why their departure from natural is considered slightly less than for the main lower Burdekin River channel. Despite this, and although convincing data are generally lacking, the health of the lower Burdekin River is considered to be relatively ‘healthy’ (Burdekin Water Resource Plan Technical Advisory Panel – Brizga et al. 2006, Butler 2006, Burrows and Butler 2007). The distributory streams are greatly affected by loss of aquatic weeds, modified hydrology, loss of riparian vegetation and local run-off, affecting their health and functionality (BBIFMAC 1999, Perna 2003, 2004, Tait and Perna 2001). The limnology of two sites within this sub-division (Payards Lagoon and Kellys Lagoon, both on Sheep Station Creek) were assessed by Loong et al. (2005). Bird (2004) also undertook a limnological investigation of several large lagoons along Sheep Station Creek, finding that turbidity decreased downstream and that the dissolved oxygen status of the turbid lagoons was more stable than for the downstream lagoons with greater water clarity. Although part of Sheep Station Creek, the Kelly’s and Castelanelli’s lagoons (#7) are off the main creek channel down which turbid water is passed and thus do not usually receive turbid irrigation water, hence why their condition is rated better than the rest of Sheep Station Creek and the other delta distributory streams. Bird (2004) also provides some water quality data on Kelly’s Lagoon, showing how it differs from the other Sheep Station Creek lagoons. Lower Cassidy Creek has artificial flow of elevated salinity associated with groundwater dewatering from adjacent agriculture. This has greatly altered the water quality compared to natural and although very little is known about the system, review of the limited amount of available information (NRA 1998) suggests that it is relatively ‘healthy’.

Reference: Assessing the condition of Wetlands in the Burdekin catchment

For more information see Burdekin Delta wetland condition summary

Water

SedNet Modelling of Water Quality

Model results for the Burdekin Delta subcatchment are summarized as follows:

  • Subcatchment modelled area: 567 sq. km.
  • Source contributions: Hillslope = 30%; Gully = 3%; Streambank = 67%
  • Area of subcatchment with <50% ground cover: 13 sq. km or 2% of subcatchment
  • Hillslope sediment supply (normalized to area): 575 kg/ha/yr
  • Total suspended sediment (flow weighted) supply: 564 kt/yr
  • Total suspended sediment supply (normalized to area): 1,906 kg/ha/yr
  • Mean Annual Flow: 9,493,686 ML

Reference: Improved SedNet Modelling of Grazing Land in the Burdekin Catchment

The modelled area of the Burdekin Delta subcatchment is vastly less than the true area of the subcatchment. Furthermore, the SedNet has not proven to adequately reflect sediment mobilization and delivery processes on floodplains where there is little or no elevation. The model results are therefore, not considered to be reliable.

Water Quality Monitoring

The monitoring sites in the Burdekin Delta:

  • Sheep Station Creek is located near Five Ways Crossing and has been sampled by the ACTFR for 2 years. The catchment area for this monitoring site is 78 sq km, of which 39.8% is used for grazing and 55.97% for cropping.
  • Plantation Creek is located on the Rita Island Road and has been sampled by the ACTFR for 2 years. The catchment area for this monitoring site is 35 sq km, of which 92.42% is used for cropping.
  • Iyah Creek is located just south of the Bruce Hwy crossing and has been sampled by the ACTFR for 2 years. The catchment area for this monitoring site is 17 sq km, of which 100% is used for cropping.

These sites in the Burdekin Delta catchment have a constant year-round flow which is fed by the Burdekin River (Clare Weir). TSS concentrations were relatively low in these sites (mean TSS concentration range from 19 to 29 mg/L) compared to other monitoring sites on the coastal plain within the Burdekin Region. The monitoring results for suspended sediments are considerably lower than predicted by the SedNet model. Concentrations of oxidised nitrogen (nitrate + nitrite) were in the low to intermediate range (mean oxidised nitrogen concentration range between 105 and 276 ug/L). Phosphate concentrations were relatively high at Plantation and Sheepstation Creeks and were low to intermediate at Iyah Creek.

Herbicide residues have been detected in the Burdekin delta sites including ametryn, atrazine and diuron, which have been detected with considerably frequency in this catchments, while hexazinone, simazine, 2,4-D, metolochlor and tebuthiuron have been detected less commonly. These herbicides with the exception of tebuthiuron and possibly simazine are sourced to the sugar industry. Tebuthiuron is sourced to the grazing industry and has been detected in the channel inflow waters upstream of these sites within the Burdekin Delta. Of these herbicides, atrazine, diuron and tebuthiuron are considered of most concern in the region.

Relevant information of Water Quality Monitoring in the Lower Burdekin River Basin:

Environmental Uses and Values

Aquatic Ecosystems

Two areas of the Burdekin Delta subcatchment have been identified as containing High Ecological Value (HEV) waters by the BWQIP ecological values technical panel. These areas correspond to: (i) the estuarine wetlands within Bowling Green Bay National Park, which is recognised internationally as a Ramsar wetland that provides important breeding and feeding habitat for water birds and other avifauna; and (ii) estuarine wetlands at the mouth of the Burdekin River. The aquatic ecosystems values of the Burdekin River, and Plantation and Kalamia Creeks are considered to be Highly Disturbed (HD) due to the altered flow regime and irrigation tailwater entering the streams. The human use Environmental Values of the subcatchment waters are understood to include recreation (swimming, boating & visual appreciation), irrigation, farm water supply, stock watering, aquaculture, industrial use, human consumption of aquatic food, and the cultural and spiritual values of the Juru traditional owners.

The Burdekin River delta region provides an important fishery, both commercially and recreationally. It is a declared Fish Habitat Area of management level ‘B’. The Burdekin River delta is specifically rich in mangrove species and seagrasses. The introduction and expansion of irrigation in the Lower Burdekin caused a decline in groundwater and subsequent seawater intrusion. Mangroves and seagrasses directly support local and offshore fisheries through the provision of food, shelter, breeding and nursery areas. It is estimated that the estuarine habitats provided by mangroves and seagrasses are critical to more than 75% of commercially and recreationally important fish and crustacean species during some phase of their life cycle (e.g. prawns, mud and sand crabs, barramundi, whiting, flathead, bream and mullet).

The environmental values of Bowling Green Bay are reflected in the green zoning of areas adjacent to the National Park by GBRMPA. The green zone includes, for example, seagrass beds important as dugong and turtle foraging habitat, populations of the inshore Indo Pacific humpback and Irrawaddy dolphins, and fish nursery areas, and a primary Grunter fish spawning aggregation site. The green zone also provides added protection to the Bowling Green Bay Dugong Protection Area and the Queensland Government declared Bowling Green Bay Fish Habitat Area. Level A. It is an extensive baitfish breeding area and many commercial and recreational fish species feed here, such as black marlin, sailfish and Spanish mackerel.

Bowling Green Bay encompasses a suite of wetlands and coastline, and has gained international recognition as a significant habitat for waterfowl. It is listed under the Ramsar Convention. Bowling Green Bay is part of Bowling Green Bay National Park, which covers 55,000ha of coastal and mountainous country. The park has a diversity of habitat types ranging from mangroves at sea level to rainforests on the mountain tops of Mt Elliot, reaching a height of 1 342 metres making it one of the highest peaks in Queensland. Bowling Green Bay contains examples of the richest coastal habitats typical of north-eastern Australia’s coastal wet-dry tropics. The wetlands are diverse and include intertidal seagrass beds, mangrove and saltpan communities and forested, brackish and freshwater swamps. Nine species of mangrove grow in the wetland, providing a nursery and shelter for fish, mud crabs and prawns. The Bay’s mangrove communities trap tide-borne sediments and help control coastal erosion. The mangroves provide vital protection from strong winds, tidal surges and heavy rainfall associated with cyclones which occasionally affect this part of Queensland’s coastline.

There are at least thirty different species of birds that migrate to the park from various parts of the world in the winter months. Brackish and freshwater wetlands behind Bowling Green Bay support many waterbirds. The wetlands seasonally support more than 20,000 waterfowl (including 4000 brolgas) and 10,000 magpie geese. Almost half of the 244 bird species known to visit the area breed in the Bowling Green Bay wetlands. Bowling Green Bay is an important feeding and breeding ground for brolgas and magpie geese. The Bay has the largest concentrations of these species in north-east Queensland and is the main stronghold of these species in eastern Australia. The endangered little tern breeds on Bowling Green Bay spit and has been observed in flocks of 1000.

Burdekin River Estuary. Protected Status: GBRWHA; Fish Habitat Area of management Level B. Upstream connectivity and salinity regimes disrupted (mainly in dry season) by weirs, sand dams and tidal barrages associated with irrigation development; fish barriers; elevated concentrations of sediments and nutrients entering waterway; freshwater flows from irrigation tail water into "naturally" saline areas. (One recreational group considered this a pristine fishing area).

Plantation Creek Estuary. Protection status: GBRWHA. Upstream connectivity disrupted by bund walls; use of waterway as an irrigation and tailwater channel; fish barriers; elevated concentrations of sediments, nutrients and pesticides entering waterway; freshwater flows from irrigation tail water into "naturally" saline areas may occur during the dry season.

Irrigation

Significant use of surface and groundwater for irrigation of sugar cane.

Farm water supply

Some water for farm water use but considered minimal in comparison to the amount of water used in irrigation.

Stock Watering

Limited use. Beef cattle are a minor industry and water user in this area.

Aquaculture

Freshwater farming of Barramundi.

There is Black Tiger Prawn farming near Alva Beach. It is believed there are 10 such operations. Fresh water consumption of prawn farming is estimated at 25.9 ML/ha/crop The Burdekin delta is considered highly suitable for land-based saltwater prawn farming due to the mostly suitable quality of groundwater and the long growing season. However, questions have been raised as to the possible off-site impact of aquaculture operations through suspected leaking ponds on adjoining grazing and cane properties.

Human Consumption of Aquatic Foods

Consumption of fish and seafood from recreational fishing and commercial fishing in the Burdekin Delta estuaries. No significant commercial freshwater fishing. Subsistence hunting, fishing and collecting by Juru Traditional Owners.

Primary Recreation

Alva at Lynch’s Beach: swimming, sailboarding.

Hutchings Lagoon: water-skiing

Secondary Recreation

Recreational fishing and boating.

Plantation Creek Landing: Fishing. Commercial fishers cannot fish in Plantation creek past a certain point with signs.

Hell Hole Boat Ramp: Recreational fishing.

Alva at Lynch’s Beach: Recreational Fishing.

Groper Creek at Mt Alma Road: Recreational Fishing.

Visual Recreation

Plantation Creek: Plantation Park, on Juru walking track, flora, fauna, bird watching and a flying fox colony. Burdekin Visitor Information Centre, Gubulla Munda, and the Gudjuda Reference Group Centre.

Plantation Creek Landing: bird watching.

Payard’s Lagoon: Bird watching.

Hutchings Lagoon: Picnicking.

Groper Creek at Mt Alma Road: Wetlands, bird watching, camping, picnicking.

Hell Hole Boat Ramp: Bird watching, chitel deer spotting.

Alva at Lynch’s Beach: bird watching, picnicking camping/caravaning.

Alva Beach: Recreational huts.

Industrial Uses

Water for industrial purposes is included in urban consumption and includes water used in sugar mills.

Sand and gravel extraction at Sheepstation Creek.

Cultural and Spiritual

Traditional use of natural resources (plant and animal) by Juru Traditional Owners.

References:

Landuse

Principle land uses within the Burdekin Delta subcatchment as a proportion of total area:

  • Grazing: 25.8%
  • Water: 16.4%
  • Conservation & minimal use: 11.9%
  • Urban & semi urban: 1.6%
  • Irrigated horticulture & cropping: .7%
  • Dryland agriculture: Limited Dryland agriculture activity use identified.

Land Condition

Definition of ABCD land condition framework

No data available for land condition in the Burdekin Delta sub-catchment.

Ground Cover

No data available for Ground Cover in the Burdekin Delta subcatchment.

Resource Condition Summary

Burdekin Delta is a small subcatchment where the major land use is irrigated sugar production, while around 26% of the land area is used for grazing on natural pastures. Approximately 28% of the land is set aside for conservation or other minimal use. Riparian habitat in the subcatchment has declined over the last 30 years due to clearing of vegetation along the floodplain and upper subcatchment. The subcatchment was in poor (C) condition in the 1970s, but by 2004 its condition had declined to very poor (D). The Burdekin Delta subcathment contains perhaps the greatest concentration of wetland habitat in the entire Burdekin catchment, but because of the intensive urban and agricultural land uses, many of the creeks and wetlands have been highly modified from their original state. The flow regime of the Burdekin River has been altered by the release of water from the Burdekin Falls Dam, while the numerous creeks within the subcatchment now have perennial flow from tailwater discharge of irrigated agriculture. However, the Burdekin River and some creeks and wetlands retain significant ecological values.

Stream bank erosion is identified by models as the major source of sediment and particulate nutrients affecting water quality within the Burdekin Delta subcatchment, while hillslope erosion is also predicted to contribute to the total sediment load. The rate of soil erosion is predicted to be quite high and close to the Basin average, while the total soil loss from the subcatchment to waterways is comparatively low. There are no rapid assessment data for grazing land condition and ground cover available for the subcatchment, however, analysis of ground cover from satellite imagery shows consistently high cover from 1998 to 2006.

Water quality in the Burdekin River is predicted by models to be only slightly impacted by suspended sediment during wet season event flows. However, the sediment load at end-of-catchment is derived not only from the Burdekin Delta subcatchment, but from the entire Burdekin River catchment upstream. Furthermore, rainfall and irrigation tailwater from the subcatchment does not drain into the Burdekin River, but into a myriad of creeks and groundwater, and then directly into coastal waters. Water quality monitoring data from Sheep Station, Plantation and Iyah Creeks have recorded exceptionally low concentrations of suspended sediment. These results support observations that very little soil is eroded from cane farms in the Lower Burdekin Basin and that the SedNet model results poorly reflect hillslope erosion on flat landscapes such as the lower Burdekin floodplain. In contrast, moderately elevated dissolved inorganic nitrogen concentrations have been recorded from the Burdekin Delta subcatchment creeks. Several herbicide residues have regularly been detected in Sheep Station, Plantation and Iyah Creeks, including atrazine, diuron and ametryn. Very many samples contained atrazine and diuron concentrations that exceeded ecosystem health guidelines.

The area of sugar production in the Burdekin Delta subcatchment is identified as a priority focus for improved management practice to reduce fertilizer and herbicide loss to waterways on the basis of the moderately elevated dissolved inorganic nitrogen concentrations, and elevated concentrations of several herbicides that are associated with sugar production.

Draft Environmental Values

Two areas of the Burdekin Delta subcatchment have been identified as containing High Ecological Value (HEV) waters by the BWQIP ecological values technical panel. These areas correspond to: (i) the estuarine wetlands within Bowling Green Bay National Park, which is recognised internationally as a Ramsar wetland that provides important breeding and feeding habitat for water birds and other avifauna; and (ii) estuarine wetlands at the mouth of the Burdekin River. The aquatic ecosystems values of the Burdekin River, and Plantation and Kalamia Creeks are considered to be Highly Disturbed (HD) due to the altered flow regime and irrigation tailwater entering the streams. The human use Environmental Values of the subcatchment waters are understood to include recreation (swimming, boating & visual appreciation), irrigation, farm water supply, stock watering, aquaculture, industrial use, human consumption of aquatic food, and the cultural and spiritual values of the Juru traditional owners.

Maps

Rferences

BurdekinDelta.jpg
Download Catchment Layer as *.kml (requires Google Earth)

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