Territory Stories

The Water Quality of the Blackmore Estuary., Darwin Harbour: May and June 2001



The Water Quality of the Blackmore Estuary., Darwin Harbour: May and June 2001


Dixon, I. H.; Padovan, Armando V.


E-Publications; E-Books; PublicationNT; Report No. 19/2003




Blackmore Estuary


The primary aim of this study was to obtain data on the water quality of the upper reaches of Blackmore Estuary in Darwin Harbour at a time when development in the catchment is relatively minor. Future development within the Blackmore Estuary catchment may alter the quality of water flowing into the estuary and in turn the main body of Darwin Harbour. Results from this study can be used as a baseline data set, against which to measure any future changes.; Made available via the Publications (Legal Deposit) Act 2004 (NT).

Table of contents

Summary -- Introduction -- Methods -- Results and discussion -- Conclusions -- References -- Appendix A-B




Salinity; Water clarity; Nutrients; Algae

Publisher name

Northern Territory. Department of Infrastructure, Planning and Environment

Place of publication



Report No. 19/2003

Now known as

Northern Territory. Department of Environment and Natural Resources


iii, 69 pages : some colour illustrations, some colour maps, tables ; 30 cm.

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Copyright owner

Check within Publication or with content Publisher.

Parent handle


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Page content

46 Soluble Reactive Phosphorus Average surface concentrations of soluble reactive phosphorus (SRP) for each location are shown in Figure 31. Concentrations ranged from 0.004 mg L-1 at locations 5 and 6, to 0.013 mg L-1 at location 9 in May and from 0.005 mg L-1 at locations 10 and 11, to 0.014 mg L-1 at location 9 in June. SRP made up approximately 20-50% of the total phosphorus pool. SRP had erratic variations in concentrations measured across the channel width in May (Figure 32). Location 7 had the greatest range of 0.007 mg L-1. In June, concentrations were more similar across the channel width, with negligible variations of less than 0.002 mg L-1. Temporal changes between May and June did not show any consistent pattern (Figure 31). Approximately half of the locations showed minor increases of up to 0.004 mg L-1. The remaining locations showed minor decreases of down to 0.002 mg L-1. Surface concentrations generally decreased with distance from freshwater inflows (Figure 31). Location 5 was an anomaly to this spatial trend in May, as it had lower concentrations of SRP than some locations further seaward. The tidal creeks, especially Middle Creek, generally had higher concentrations than the main estuary channel. Padovan (1997) measured surface SRP in the main body of Darwin Harbour to be mostly in the range of 0.004 to 0.005 mg L-1 in May and June 1991. These concentrations are generally lower than those measured in Blackmore Estuary, and like TP, this suggests that by the time SRP reaches the main body of the harbour, concentrations are considerable diluted or consumed by the ecosystem. Overall, SRP surface concentrations were low, with the highest concentrations measured in the tidal creeks and gradually decreasing with distance from freshwater inflows.

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