Moreton Bay Catchments
Bramble Bay is an embayment of Moreton Bay which extends from the mouth of the Brisbane River north to Woody Point at the Redcliffe Peninsula. Bramble Bay is the most degraded embayment of Moreton Bay. This is primarily a result of the high levels of nutrients and sediments that are transported into Bramble Bay from the Brisbane and Pine Rivers.
Historically, dugongs and turtles grazed on seagrass beds within Bramble Bay, but high turbidity and nutrients eliminated these beds at least 30 years ago. Current water quality conditions of Bramble Bay are unsuitable for the re-establishment of seagrass meadows. Nitrogen in the Bramble Bay zone has been decreasing since the upgrade of the Luggage Point Waste Water Treatment Plant (WWTP) in 2001. However, poor flushing continues to contribute to the poor condition of this catchment, the area possessing the longest residence time of Moreton Bay (59 to 62 days).
Healthy Waterways has monitored 11 sites within Bramble Bay on a monthly basis since 2000.
Cabbage Tree Creek
The Cabbage Tree Creek catchment covers 45 square kilometres from the bushy foothills of the Taylor Range, through residential and industrial areas of northern Brisbane to Moreton Bay. The catchment acts as a corridor for animals to travel from the large bushland areas of D’aguilar National Park to the coastal lowlands and wetlands, and bushland reserves. Following requests from the community, Brisbane City Council protected Boondall Wetlands for conservation and recreation purposes. The largest protected wetland of this type in Brisbane, it is home to numerous animals including 190 species of birds and numerous marine and terrestrial fauna.
Sandgate Sewage Treatment Plant (STP) discharges into the Cabbage Tree Creek estuary. Upgrades to the facility between 2005 and 2008 resulted in total nitrogen reductions to the system. This estuary is flushed with poor quality water from Bramble Bay and being relatively small has a low dilution capacity compared to other estuaries that receive large flows from WWTPs.
Healthy Waterways has monitored 6 sites along Cabbage Tree Creek Estuary on a monthly basis since 2000.
The Caboolture River catchment, with a total area of 468km², is the third largest catchment in the Moreton Bay Catchments reporting zone. The upper catchment contains the undistributed streams of the D’Aguliar Range. There are no dams on the waterway, except for a weir and the only major crossing is the Bruce Highway bridge. The Caboolture River is tidal for 19 km upstream to the Caboolture Weir. At the river mouth a sand bar reduces the impact of tidal energy.
Today, as many of Queensland's smaller towns decline, Caboolture is experiencing rapid growth. While agriculture retains its importance, it is becoming increasingly urbanised posing a threat to the river from land clearing and stormwater run-off. Two sewage treatment plants (STPs) discharge into the Caboolture River. Recent upgrades to the Caboolture Sewerage Treatment Plant have effectively reduced some of the pollution impacts.
Healthy Waterways has monitored 10 sites on the Caboolture River Estuary on a monthly basis since 2000.
The Central Bay reporting zone is an area of water within Moreton Bay beginning near Victoria Point in Redland Bay and spanning northwards to the south of Bribie Island. Moreton Bay is separated from the Coral Sea by a chain of three sand islands – Moreton Island in the north, North Stradbroke Island, and South Stradbroke Island in the south.
The bay contains several protected zones including parts of the bay protected as RAMSAR wetland. Moreton Bay is home to the one of the largest Australian population of dugong and several species of turtle, including the most significant population of Loggerhead Sea Turtle.
The waters are a popular destination for recreational anglers and are used by commercial seafood operators. However, after the 2011 floods, fishermen were warned not to eat or catch seafood in the area due to contamination from sewerage, pesticides, heavy metals such as lead and zinc as well as hydrocarbons.
Healthy Waterways monitors 14 sites within Central Bay.
Deception Bay is situated at the northern section of Moreton Bay from Newport up to the south of Bribie Island and receives input from the Caboolture River, Pumicestone Passage and several other streams including Burpengary Creek.
Extensive seagrass meadows are present in the northern part of the bay but have been threatened by toxic Lyngbya blooms. Lack of seagrass recovery is likely due to discharge of poor quality water from the Caboolture River which remains a pressure on Deception Bay's overall ecosystem health. Poor flushing resulting in turbidity in that area of Deception Bay compounds the impact of this discharge.
Since 2002 Healthy Waterways has monitored 9 sites within the Deception Bay reporting zone.
The Eastern Banks reporting zone is an area of water spanning between Moreton and Raby Bay. Eastern Banks is centred in the bay side zone between the south end of Moreton Island and the tip of North Stradbroke which includes the coastal waters around Crab Island. The zone is only very small, reporting 3 sites from mid 2000, consistently receiving high gradings for water quality since 2003. This small section of coastal space is the bay entrance between Moreton and North Stradbroke Island.
Healthy Waterways has monitored 3 sites since 2000.
The Eastern Bay reporting zone is an area of water spanning between Moreton Bay, Raby Bay and Toondah Harbour. Eastern Bay runs along the bayside coast of Moreton Island and stretches across to the south eastern end of Bribie Island. The zone then runs down the coast side of North Stradbroke Island, wrapping around the Eastern Banks reporting zone as it passes between Stradbroke and Moreton Island. The reporting zone also includes Peel Island and the Eastern sides of some of the smaller islands including Lamb and Macleay.
Healthy Waterways has monitored 11 sites since 2000.
The Eprapah Creek Catchment forms part of the Redland Creeks catchment and is the smallest of the Moreton Bay Catchments reporting zones, with an area of 281km². The Eprapah catchment has undergone rapid development from market garden and agricultural land to that of urban in recent years. The upstream catchment has been adversely affected by large-scale poultry farms, wineries, land clearance and semi-urban development. The recent works included the constructions of new shopping centres and residential lots less than 500 meters from the estuary in 2003-04.
Like most small subtropical estuaries, Eprapah Creek is characterised by short-lived freshwater flushing and low flow during the dry season. Although the estuarine zone includes two environmental parks, there are some marinas and boat yards, and a major sewage treatment plant which discharges into the creek. The creek ultimately discharges into Waterloo and Moreton Bay at Victoria Point.
Healthy Waterways has monitored 4 sites on Eprapah Creek Estuary on a monthly basis since 2003.
The Oxley Creek catchment forms part of the Lower Brisbane River catchment and is Brisbane's longest and the only sand-based creek in the city. Oxley Creek discharges into the Brisbane River Estuary approximately 46km upstream from Moreton Bay. Residential and industry development, sewage, sediment, land clearing and sand mining in the catchment have greatly affected the water quality of Oxley Creek, particularly in its lower reaches.
Key environmental issues that face the catchment include:
- rapid population increase and development;
- altered flow patterns of the creek causing active erosion;
- deteriorating water quality;
- increased noise and vehicle movements;
- waste disposal;
- invasion of bushland by exotic plants and animals;
- management of the extractive industries; and the
- day-to-day behaviour of residents and workers of the catchment.
Healthy Waterways has monitored 5 sites on Oxley Creek Estuary on a monthly basis since 2002.
The Pine River catchment is the second largest in the Moreton Bay Catchments reporting zone, with an area of 825km². There are 1,770km of stream networks in this catchment of which 17km are defined as estuarine for reporting processes. Part of the upper catchments of the North and South Pine River are between Brisbane Forest Park and Bunyaville State Forest. North Pine River is impounded by the North Pine Dam and forms Lake Samsonvale. The Murrumba Downs STP discharges into the northern branch of the Pine River. This STP has not been upgraded over the course of the study.
Healthy Waterways has monitored 6 sites on the Pine River Estuary on a monthly basis since 2000.
The Tingalpa Creek catchment, forms part of the Redlands Creek catchment and is the smallest of the Moreton Bay Catchments reporting zone, with an area of 281km². The other major creek in this catchment is Eprapah Creek. There are 525km of stream networks in this catchment, of which 11km of Tingalpa Creek are defined as estuarine for reporting processes. This catchment has undergone rapid development from market garden and agricultural land to that of urban in recent years. There are two Sewage Treatment Plants (STPs) that discharge into Tingalpa Creek.
Healthy Waterways has monitored 7 sites on Tingalpa Creek Estuary on a monthly basis since 2003.