Hon Alison Xamon asks about nitrate levels in Swan Canning Rivers. The Minister provides some data on annual flow and nitrogen concentrations, but full data and projections are unavailable pending further calculations and long-term action.

AnsweredQoN 3210Legislative Council
Asked
24 November 2010
Portfolio
Environment

QuestionView source ↗

In relation to the Swan Canning Rivers – nitrate concentration, load, trend and targets, I ask -.
(1) For each of the 15 monitored Swan – Canning sub-catchments during 2010, what was the:
(a) annual flow;
(b) median concentration of Total Nitrogen (mg/L); and
(c) load of Total Nitrogen (t/year)?
(2) Based on current trends for each catchment, in what year will median concentrations and loads of Total Nitrogen meet the long term maximum acceptable load of 130 tonnes of Total Nitrogen to the Swan Canning Rivers?

AnswerView source ↗

Answered
14 March 2011
Responded by
Minister for Child Protection representing the Minister for Environment
Response time
110 days
(1a) I am advised by the Swan River Trust that only some of the annual flow data for 2010 is available for the monitored Swan Canning catchment sites.  Data for the remaining sites is in the process of being collected and collated and will be available from the Trust later in 2011. The 2010 annual flow data that is available is as follows:
Bayswater Main Drain - 4,337 ML
Bennet Brook - 2,245 ML
Canning River - 3,195 ML
Ellen Brook - 2,281 ML
Helena River - 1,710 ML
Jane Brook - 887 ML
Southern River - 5,880 ML
Susannah Brook - 377 ML
(b) The annual median total nitrogen concentrations for 2010 for the 15 monitored Swan-Canning sub-catchments are as follows:
Avon River - 0.7 mg/L
Bannister Creek - 1.4 mg/L
Bayswater Main Drain - 1.3 mg/L
Bennett Brook - 1.1 mg/L
Bickley Brook - 0.9 mg/L
Blackadder Creek - 1.0 mg/L
Ellen Brook - 2.0 mg/L
Helena River - 0.6 mg/L
Jane Brook - 0.4 mg/L
Canning River - 0.3 mg/L
Mills Street - 1.0 mg/L
Southern River - 1.3 mg/L
South Belmont - 0.7 mg/L
Susannah Brook - 0.7 mg/L
Yule Brook - 0.8 mg/L
(c) I am advised by the Swan River Trust that total nitrogen loads for 2010 are currently not available as they are yet to be calculated and will be available later in 2011.
(2)  I am advised that the maximum acceptable load of 130 tonnes of Total Nitrogen is a long term target which will require continued on-ground action to reduce the input of nutrients and contaminants from entering our river system over several decades.
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