Source:Auckland Council Research and Evaluation Unit, RIMU
Auckland Council operates a long-term river water quality monitoring programme throughout the Auckland region. The primary objective of this monitoring is to report on the State of the Environment (SoE), as part of an assessment of the efficacy of Auckland Council’s policies, rules, initiatives and strategies in undertaking its environmental management responsibilities under the Resource Management Act 1991 (RMA). This monitoring also helps underpin the requirement to take appropriate action (having regard to the methods available to the council under this Act) where this is shown to be necessary. This report provides a summary of the data collected during 2017 for selected rivers across the region
Water quality is assessed monthly at 36 sites around the region using a combination of field and laboratory tested parameters. Annual water quality results are summarised as box plots to display the variation in the parameters measured at each of the sites, and this is supplemented with tables providing related basic summary statistics. The annual reporting provides an interim summary of water quality between the more comprehensive five yearly ‘state and trend’ reporting Auckland Council also produces to assess its environmental management responsibilities.
A water quality index is calculated for the purpose of comparing overall water quality across sites and communicating this complex water quality data in a simple, easily understandable form. The sites are then ranked and assigned a water quality class based on this water quality index.
In 2017, the West Hoe Stream, a native forest site, was the only site classed as having ‘excellent’ water quality and ranked highest for water quality class in the region. By contrast, ‘poor’ water quality was observed in streams with a greater mix of urban and/or rural land cover. The two Pakuranga Creek sites (Botany Road and Greenmount Drive) had the lowest ranked water quality index scores in 2017. These are both predominantly urban sites in terms of land cover.
Auckland Council technical report TR2019/010