Area grade: B
What makes up this grade?
The overall grade is made up of five indicators:
Water quality: Water samples are tested for temperature,
oxygen concentration, turbidity and the levels of pH, ammonia and nutrients
(nitrogen and phosphorus). The results of this testing are compared against
guidelines for Auckland to produce a water quality index.
Flow patterns: This involves monitoring the hydrologic
connectivity of the river to upstream and downstream reaches and the floodplain
using the Stream Ecological Valuation (SEV), which is a method of assessing the
ecological health of our rivers.
Nutrient cycling: This involves monitoring the inputs and
processing of minerals, particulates and contaminants using the SEV
Habitat quality: This involves monitoring the diversity and
quality of habitats using the
SEV habitat provision functions.
Biodiversity: Field assessments and samples are collected to
assess the type and amount of native plants and animals using the SEV
- The reporting area covers 155KM2 representing 3.2% of the region - the ninth largest reporting area
- Land cover is a mix of pastoral vegetation (46%) AND native vegetation
- The extent of impervious surface (hard surfaces) is LOW (7%) when compared
with the regional average of 9%
Monitoring background and interpretation
Auckland Council’s State of the Environment (SoE) monitoring programme has
been building a record of Auckland’s environment for more than 25 years. This
information is critical to the effective management of Auckland’s natural
environment, after all, you can’t manage what you don’t monitor.
The monitoring programme shows there is a strong relationship between the
health of rivers and the type of land cover in the surrounding catchment. Rivers
that drain through forested catchments (particularly native forests) typically
have excellent water quality and ecology, while rivers that drain from urban
catchments typically have poor water quality and ecology.
The Waiheke reporting area is predominantly pastoral, but with large forested
areas still remaining. As a result, the health of the area’s rivers is
considered to be good. Rivers in this area tend to have riparian margins with
some trees and bush, which provide shade, leaf litter and woody debris to the
stream and anchor the stream banks. The debris enhances the quality of habitat
for flora and fauna, although some of the original riparian vegetation has been
removed to allow more intensive land use. The low level of urban development
means there is little channel modification or pollution from discharges or
stormwater, although there may be diffuse sources of contaminants from the
pastoral land use and physical damage from stock access.
The data used to produce this report card is from:
|Rural average*||||Water quality||2013-2015|
|Home Bay Stream||Motutapu Island||SEV||2014|
|Cascades Stream||Whakenawha Regional Park||SEV||2014|
|Onetangi Stream||Forest and Bird Reserve||SEV||2014|
* It is impossible to monitor every characteristic of every freshwater
environment, hence for some areas, such as Waiheke, we monitor ecological health
but have used results from similar catchments to infer water quality.