Territory Stories

Darwin Harbour in good health



Darwin Harbour in good health


Westra Van Holthe, Willem

Political affiliation

Country Liberals


Media Releases for 12th Assembly 2012 - 2016; Media Releases; ParliamentNT






Made available by via the Publications (Legal Deposit) Act 2004 (NT)




Oceans; Marine life

Publisher name

Northern Territory Government

File type



Issued as a Media Release

Copyright owner

Northern Territory Government

Parent handle


Citation address


Related items

https://hdl.handle.net/10070/528211; https://hdl.handle.net/10070/528213

Page content

30 Blackmore River 2014 5.6 Blackmore River Upper The estuary is characterised by a relatively long residence time in the upper reaches compared to outer and middle parts of the harbour. Blackmore River Estuary receives occasional discharges from licensed aquaculture operations, and sediment and nutrient loads from diffuse sources in the wet season. The upper reaches are also subject to persistent freshwater flows from springs which continue to flow during the dry season in addition to flows maintained in Darwin River downstream of the Darwin River Dam. Figure 13 summarises the results of each water quality parameter measured at the Blackmore River Estuary monitoring sites. Table 10 below reports median values and 20th-80th percentiles (compliance), minimum and maximum values of the data measured. Table 10 - Summary of water quality parameters measured in Blackmore River estuary All water quality parameters measured complied with the WQOs: Water quality in the Blackmore River estuary reporting zone is in excellent condition. The lowest pH and dissolved oxygen values were measured in upper parts of the estuary. Dissolved oxygen, ammonia, total nitrogen and total phosphorus measured in upper parts of the area were generally higher compared to those measured in more open parts and indicated strong gradients decreasing with distance along the estuary. Total suspended solids and chlorophyll a is generally lower during the dry season months in comparison to the wet season where water quality can fluctuate widely. Indicators Water Quality Objectives Blackmore Upper min-max 20th-80th percentiles and (median) pH 6.5-8.5 6.83-7.98 7.5-7.7 (7.5) Dissolved oxygen (% saturation) 80-100 66.6-108 72-93 (87) Suspended solids (mg/L) <10 0.9-10 2.6 Chlorophyll a (g/L) <4 0.41-5 1.59 No (g/L) <20 3-66 13 Ammonia (g/L) <20 1-35 3 Total nitrogen (g/L) <300 40-470 150 Total phosphorus (g/L) <30 5-40 5 Filterable reactive phosphorus (g/L) <10 1-20 4 2014 rating A 30