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Overview

Greater Wellington Regional Council (GWRC) routinely monitors water quality in two lakes in the Wellington Region, Lake Wairarapa and Lake Onoke. Monitoring in Lake Wairarapa commenced in 1994 and the programme remained largely unchanged until 2012/13 when changes in monitoring frequency and some site locations and variables were implemented (see Cockeram & Perrie 2013 and Cockeram & Perrie 2014). In August 2009, water quality monitoring programmes were established for two additional lakes, Onoke and Waitawa. Monitoring of Lake Onoke is ongoing while monitoring of Lake Waitawa is restricted to 12-month periods every five years (initially in 2009/10 and then again in 2014/15).

In 2011 assessments of ecological condition, based on submerged macrophyte community structure and composition, were introduced for Lakes Kohangapiripiri, Kohangatera and Pounui. Assessments of macrophytes in all three of these lakes, as well as an inaugural assessment in Lake Waitawa, last occurred in early 2016. LakeSPI assessments are planned to occur every five years.

Monitoring network

Scroll/zoom on the map to find areas of interest. Click on a site to see more information.

1Auxiliary sites sampled to help inform the relative effects of the discharges from Lake Wairarapa and the Ruamahanga River on water quality in Lake Onoke.

Monitoring objectives

  1. Assist in the detection of spatial and temporal changes in the condition of selected lakes;
  2. Contribute to our understanding of freshwater biodiversity in the Wellington Region;
  3. Determine the suitability of lakes for designated uses;
  4. Provide information to assist in targeted investigations where remediation or mitigation of poor water quality or ecosystem health is desired; and
  5. Provide information required to determine the effectiveness of regional plans and policies.

Monitoring results

State assessments presents current lake status as assessed by the Trophic Lake Index (TLI), GWRC Proposed Natural Resources Plan (PNRP), and National Policy Statement for Freshwater Management National Objectives Framework (NOF). Links are provided with each for more information.

Supplementary data provides annual summaries of dissolved oxygen, water temperature, pH, conductivity, visual clarity, turbidity, suspended solids, chlorophyll a, and dissolved and total nutrients.