River and stream water quality and ecology - Greater Wellington ...

River and stream water quality and ecology in the Wellington region: State and trends
1. Introduction
Greater Wellington Regional Council (Greater Wellington) manages water
quality in rivers and streams of the Wellington region for natural state, public
water supply, recreation and amenity, trout habitat, and aquatic ecosystem
health. Regular monitoring of physico-chemical and microbiological water
quality, together with assessments of ecosystem health, are integral in
managing rivers and streams for these purposes. This monitoring is also
important for understanding the potential flow-on effects for the health of
downstream receiving environments such as lakes and estuaries.
This report provides a comprehensive assessment of the results of state of the
environment water quality and ecological monitoring undertaken at 55 river
and stream sites in the Wellington region over the period January 2004 to June
2011. Monitoring the state of the environment is a specific requirement for
regional councils under Section 35(2)(a) of the Resource Management Act
(RMA) 1991.
1.1 Report purpose
This technical report is one of eight covering air, land and water resources
prepared with the primary purpose of informing the review of Greater
Wellington’s five regional plans. These plans were established to sustainably
manage the region’s natural resources, including fresh waters. The review of
the regional plans follows the recently completed review of the overarching
Regional Policy Statement (RPS) for the Wellington region (GWRC 2010).
The focus of the eight technical reports is on providing an up-to-date analysis
of monitoring information on state and trends in resource health as opposed to
assessing the effectiveness of specific policies in the existing RPS (WRC 1995)
or regional plans. Policy effectiveness reports were prepared in 2006 following
the release of Greater Wellington’s last formal State of the Environment (SoE)
report, Measuring up (GWRC 2005).
The last technical report on state and trends in river and stream health in the
Wellington region was prepared by Milne and Perrie (2005); this report focussed
on 51 sites monitored over the period 1997 to 2003. In a more recent report
following changes to the monitoring network in 2003/04, Perrie (2007)
documented the state of river and stream health at 56 sites for the three-year
period ending in August 2006 1 .
1.2 Report scope
This report assesses the current state of river and stream health across the
Wellington region and whether or not this has improved, deteriorated or
remained the same over the reporting period. The assessment focuses on
routine SoE water quality, periphyton and macroinvertebrate monitoring data
collected since 2004 (although the analysis of current state only uses the most
recent three years of data, July 2008 to June 2011). The report also includes an
assessment of state and trends in native fish communities in the Wellington
1 Greater Wellington also prepares annual summary reports documenting SoE monitoring results obtained in the last financial year. Refer
to Perrie and Cockeram (2010) for the most recent annual freshwater quality monitoring report.
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