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Freshwater management tool: report 3. Baseline state assessment (rivers)

Author:  
Auckland Council Healthy Waters Department, Nick Brown, Tom Stephens, Theo Kpodonu, Mahesh Patel, Paradigm Environmental, Dustin Bambic, John Riverson, Khalid Alvi, David Rosa, Xiaomin Zhao, Morphum Environmental Ltd, Caleb Clarke, Hana Judd, Andrew Rosaak
Source:  
Auckland Council Healthy Waters Department
Publication date:  
2021
Topics:  
Environment

Freshwater management tool: report 3. Baseline state assessment (rivers)

Extract from the Executive summary

The Freshwater Management Tool (FWMT) is a continuous and process-based water quality accounting framework for the Auckland region. In its first iteration (Stage 1) contaminants simulated include total suspended solids (TSS), total and dissolved forms of nutrients (TN, DIN, TON, TAM; TP, DRP), total forms of heavy metals (TCu, TZn) and faecal indicator bacteria (E. coli). The FWMT Stage 1 simulates the generation, transport and fate of contaminants in multiple flow paths across and through land, and ultimately through instream freshwater environments.

This report grades outputs from the FWMT Stage 1 using national and regional objective framework guidance on seven freshwater contaminants. Continuous predicted contaminant time series spanning the calendar years of 2013 to 2017 were used to calculate numeric attribute states (i.e., percentiles of instream concentration). The most conservative (poorly) graded numeric attribute states assigned overall attribute grade. However, the availability of continuous outputs enabled investigation of which numeric attribute state conservatively grades overall state, enabling greater resolution of likely contaminant pressures on water quality state.

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The FWMT Baseline State (Rivers) report includes numerous appendices designed to support water quality management decision-making to catchment level, whilst ensuring integrated accounting (ki uta ki tai). Regional and watershed summaries should not be read as definitive with high diversity in simulated sub-catchment water quality throughout the Auckland region over the baseline period. However, the FWMT Stage 1 outputs represent the first comprehensive, deterministic and integrated water quality accounting for the Auckland region.

Appendices (in preparation)

FWMT report 2021/3

Auckland Council, September 2022

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List of Freshwater Management Tool reports

1. Baseline data inputs

2. Baseline configuration and performance | Report 2, appendices (in preparation)

3. Baseline state assessment (rivers) | Report 3, appendices (in preparation)

4. Current state assessment (lakes). Not published. Inquiries to: fwmt@aucklandcouncil.govt.nz

5. Review of the freshwater management tool. Baseline state assessment (rivers)

6. Literature review of primary sector responses to water quality: efficacy and cost

7. Riparian area management scenarios. Freshwater management tool

8. Lifecycle costs and benefits for rural mitigations in the freshwater management tool

9. A total economic valuation approach to understanding costs and benefits of intervention scenarios – part 1 urban devices

10. A total economic valuation approach to understanding costs and benefits of intervention scenarios – part 2 urban source control costs

11. Recommendations for improving rural mitigation modelling in the freshwater management tool

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Inquiries to: fwmt@aucklandcouncil.govt.nz



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