The Council’s monitoring programme for the period under review included seven inspections
and two hydrological gaugings. In addition, analysis of generation data, lake level data, Patea
River flow and groundwater abstraction data, provided by the Company, was conducted. The
Council also reviewed numerous reports submitted in accordance with consent conditions.
The monitoring showed that overall the scheme was operated well, and within resource
consent requirements. The Company coordinated a
depositing in the fishpass.
h) Dirty Floods.
i) Very low river levels.
In order to establish the appropriate operational requirements, it is necessary to define the optimum
performance outcomes. The optimum performance outcome would be defined as:
Achieving peak generation performance and duration whilst still maintaining adequate habitat in the
lake, adequate residual flow in the river system and adequate fish passage in the fish pass.
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depositing in the fishpass.
h) Dirty Floods.
i) Very low river levels.
In order to establish the appropriate operational requirements, it is necessary to define the optimum
performance outcomes. The optimum performance outcome would be defined as:
Achieving peak generation performance and duration whilst still maintaining adequate habitat in the
lake, adequate residual flow in the river system and adequate fish passage in the fish pass.
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OPUNAKE Power Doc:OP:001 Rev2
year, with the abstraction
consents to take and use exercised in the reported period.
During the period under review, the Company demonstrated a good level of
environmental performance at the Motukawa power scheme.
The Council’s monitoring for the period under review included 50 inspections of fish passage
and residual flow facilities, continuous river monitoring at three sites between November and
April each year, two biomonitoring surveys and three fish surveys of receiving waters, and
flow set below the weir is 180 l/s. This represents 13.6 % of the 7-day
mean annual low flow (7-day MALF) for the Waiaua River at 1319 l/s1. The current residual
flow is very low in comparison to the standard rule-of-thumb for protecting instream values
which is setting a residual flow at 80 % of the 7-day MALF.
7. The current residual flow and operating regime reduces the flow variability in the lower river
and causes the hydrograph to flatline at a very low flow (relative to
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5
Taranaki’s landscape is dissected by more
than 20,000 kilometres of rivers and streams.
2. Overview
2.1 THE TARANAKI CONTEXT
Taranaki has 20,000 kilometres of waterways and
no less than 530 named rivers and streams.
Taranaki also has 19 lakes with an area greater
than eight hectares and over 1,200 wetlands.
Over 300 rivers flow from the flanks of Mount
Taranaki in a distinctive radial pattern across the
ring plain.
Island, it is also
recommended that samples continue to be taken by the Council at selected sites and sent
away for analysis.
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Table of contents
Page
Introduction 1 1.
1.1 Nuisance periphyton 2
1.1.1 Periphyton guidelines 5
1.1.2 Cyanobacteria 5
1.1.3 Methodology 7
1.1.3.1 Periphyton surveys 7
1.1.3.2 Periphyton index 8
1.1.3.3 Periphyton biomass 11
1.1.4 Site locations 13
Results 16 2.
2.1 Hangatahua (Stony) River 16
2.1.1 Flow and
2.1 Hangatahua (Stony) River 15
2.1.1 Flow data and survey dates 16
2.1.2 Periphyton cover 16
2.1.3 Periphyton Index Score 18
2.1.4 Periphyton biomass 18
2.1.5 Summary of 2002-2014 (12 year data set) 19
2.1.6 Long term trend analysis 20
2.2 Maketawa Stream 22
2.2.1 Flow data and survey dates 23
2.2.2 Periphyton cover 24
2.2.3 Periphyton Index Score 25
2.2.4 Periphyton biomass 26
2.2.5 Summary of 2002-2014 (12 year data set) 27
2.2.6 Long term trend analysis 28
2.3 Manganui
of component infrastructural assets to provide the
following:
security from floods in the Waiwhakaiho River up to a flood flow
of 1,180 cumecs (1% AEP) to the land in the Waiwhakaiho Basin
(The Valley);
security from floods in the Mangaone Stream up to a flood flow
of 73 cumecs (1% AEP) to the land in the Waiwhakaiho Basin;
minimal riverbank erosion; and
an unobstructed and stable flood fairway within the maintenance
reaches of the Waiwhakaiho River and Mangaone
of component infrastructural assets to provide the
following:
security from floods in the Waiwhakaiho River up to a flood flow
of 1,180 cumecs (1% AEP) to the land in the Waiwhakaiho Basin
(The Valley);
security from floods in the Mangaone Stream up to a flood flow
of 73 cumecs (1% AEP) to the land in the Waiwhakaiho Basin;
minimal riverbank erosion; and
an unobstructed and stable flood fairway within the maintenance
reaches of the Waiwhakaiho River and Mangaone