technical report Groundwater Quality – State of the
environment Monitoring 2015-2020 and notes the specific recommendations therein.
McDonald/Williamson
4. Assessment of Escherichia coli (E. Coli) load reductions required to achieve
freshwater objectives in the rivers of the Taranaki region
4.1 Ms A J Matthews, Director – Environmental Quality, spoke to the memorandum to
provide the Committee with an overview of the findings of a recent report
commissioned by the Council,
Manganui River, although due to
a mechanical failure, some flows were provided late. Monitoring shows that some improvement is necessary
in the control systems managing the provision of flushing flows to the Mangaotea Stream. This has been
formally communicated to Trustpower.
Following the establishment of the 400 L/s residual flow limit in 2002, the difference in water temperature
between natural flows in the Manganui River and those in the residual flow reach (downstream of the weir)
water monitoring site details 8
Table 3 Groundwater monitoring site details 8
Table 4 Biomonitoring site details 9
Table 5 Surface water quality results 2019 15
Table 6 Surface water quality results 2020 17
Table 7 A comparison between low flow and high flow river quality 20
Table 8 Inter-laboratory comparison results June 2020 and September 2020 20
Table 9 Surface water quality results WGG000657 23
Table 10 Surface water quality results WGG000660 23
Table 11 …
a severe weather event, while the
other two related to insufficient residual flow at a time when maintenance required the control gates to be
manually controlled. These incidents were all of short duration (no more than 4 hours).
Compliance with flushing flow requirements was good with regards to the Manganui River requirements,
but some improvement is necessary regarding the Mangaotea Stream requirements, where only one of the
four flushing flows was provided as required. This is an
Biomonitoring reports
page
List of tables
Table 1 Gauging results for gaugings undertaken in relation to the Manganui
River residual flow 25
Table 2 Gauging results for gaugings undertaken in relation to the Mangaotea
Stream residual flow, 2014-2015 monitoring period. 26
Table 3 Details of consents and special conditions in relation to abstraction rates,
discharge rates and water levels, and the recording thereof 28
Table 4 Incidents where recorded
supplies. The current understanding of the Taranaki
Groundwater resource suggests that it is not likely to play a major role as an irrigation
supply option for the region.
Analysis of surface water availability and reliability was carried out on four rivers
(Waitotara and Whenuakura in the east Hawera area and Kapoaiaia and Punehu
streams in the Opunake area). These were chosen primarily because of the flow data
available and / or the relative catchment size.
TRC does not, at present, use
Culvert
A pipe, box structure or covered or arched channel
that has an inlet and outlet which is in, and connects
the water or bed of, the same river or connected area.
Weir
An open-topped structure across the full width of any
river or connected area that:
alters the water level and the flow characteristics
of the water; and
allows water to flow passively through or over the
top.
Dam
A structure whose purpose is to impound water
Table of contents
Page
Introduction 1
Nuisance periphyton 3
Periphyton guidelines 5
Cyanobacteria 5
Methodology 7
Site locations 12
Results 15
Hangatahua (Stony) River 15
Flow and nutrient data and survey dates 16
Periphyton cover 16
Periphyton Index Score 18
Periphyton biomass 18
Summary of 2002-2018 (16 year data set) 19
Long term trend analysis 20
Kapoaiaia Stream 22
Flow data, nutrient data and survey dates 23
Company demonstrated an overall good level of environmental
performance.
The Patea HEPS was visited two times during the monitoring period, being two site inspections. In addition,
analysis was conducted of generation data, lake level data, Patea River flow and groundwater abstraction
data provided by the Company. The Council also reviewed a number of reports submitted in accordance
with consent conditions. There were no hydrological inspections programmed for the 2018-2019 period, but
predominantly related to climatic
patterns, but can also be artificially influenced by activities such as pasture irrigation onto recharge areas.
Discharge volumes are influenced by both natural processes, such as flow from springs and groundwater
seepage to rivers and the coast, and the removal of groundwater by abstraction.
The Council monitors groundwater levels at 15 sites across the region. Nine of these sites are classified as
long-term sites, where data has been collected for in excess of …