WAIKAREMOANA POWER SCHEME
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
POWER SCHEME
WAIKAREMOANA
ENVIRONMENTAL REPORT // 01.07.12 // 30.06.13
13 This report provides a summary of key environmental outcomes arising out
of the process to renew resource consents for the ongoing operation of the
Waikaremoana Power Scheme.
The process to renew resource consents was lengthy and complicated, with
a vast amount of technical information collected. It is not the intention of
this report to reproduce or replicate this information in any way, rather it
summarises the key outcomes for the operating period 1 July 2012 to 30 June
2013 (hereafter referred to as ‘the reporting period’).
The report also only provides a summary of key result areas. There are a
number of technical reports, research programmes, environmental initiatives
and agreements that have fed into this report. As stated above, it is not the
intention of this report to reproduce or replicate this information, rather to
provide a summary of it. Genesis Energy is happy to provide further details or
technical reports or discuss matters directly with interested parties.
HIGHLIGHTS
1 July 2012–30 June 2013
02 01 INTRODUCTION
02 1.1 Document Overview Maintenance Consents In February 2013, scheme-wide
02 1.2 Resource Consent Process Overview resource consents to undertake various routine maintenance
02 1.3 How to use this document activities at the Waikaremoana Power Scheme were granted
02 1.4 Genesis Energy’s Approach by Hawkes Bay Regional Council (HBRC). Prior to the scheme-
to Environmental Management wide maintenance consents, resource consents for routine
02 1.4.1 Genesis Energy’s Values maintenance activities were applied for on an ad-hoc basis
02 1.4.2 Environmental Management System which involved frequent repetition. The new consents provide
03 1.4.3 Resource Consents Management System an efficient mechanism to undertake routine maintenance
03 1.4.4 Hydrology activities, whilst effectively managing the effects of the activities
03 1.5 Feedback on the environment (see Section 5.1.1 for details).
04 02 WAIKAREMOANA POWER SCHEME
Waikareiti Biodiversity Restoration Project Genesis Energy
05 2.1 Operating the Waikaremoana Power Scheme
entered into a three year Waikareiti Biodiversity Restoration
05 2.2 Climate and Power Generation
Project Sponsorship Agreement with the Department of
06 03 LAKE WAIKAREMOANA Conservation (DOC) in February 2012. The project’s vision is
07 3.1 Hydrology that “The Waikareiti landscape is pest free and native species
08 3.1.1 Level Trends at Lake Waikaremoana thrive in abundance”. DOC field staff and tangata whenua
08 3.2 Ecosystems and Water Quality established predator trapping infra-structure around the
08 3.2.1 Terrestrial Vegetation lakeshore this reporting period ready for removal of pests from
08 3.2.2 Aquatic Vegetation all six islands on Lake Waikareiti, using hand-spread toxins
09 3.2.3 Trout Monitoring (see Section 6.3 for details).
09 3.2.4 Ecological Restoration Programme
10 3.3 Sediment (Erosion, Transport and Deposition) Waikaremoana Lagarosiphon Incursion In February 2012, a
10 3.3.1 Event-Driven Monitoring DOC contractor located Lagarosiphon plants at Te Raoa Bay
11 04 WAIKARETAHEKE RIVER on Lake Waikaremoana during routine surveillance. A multi-
12 4.1 Hydrology agency response is well underway to manage the incursion,
12 4.1.1 Lake Kaitawa involving DOC, tangata whenua, National Institute of Water and
12 4.1.2 Waikaretaheke River from Kaitawa Spillway to Atmospheric Research, HBRC, Fish and Game, user groups and
Lake Whakamarino Genesis Energy. A Ten-Year Strategic Plan has been prepared
13 4.1.3 Lake Whakamarino and ratified by the governance group this reporting period
13 4.1.4 Waikaretaheke River below Piripaua Power Station and regular dive inspections have reduced the biomass of
13 4.1.5 Maximum Flows: Waikaretaheke River and Lakes Lagarosiphon at all known sites to very low levels (see Section
Waikaremoana, Kaitawa and Whakamarino 6.6 for details).
13 4.2 Aquatic Ecosystems and Water Quality
Piripaua Transformer Upgrade After 73 years of service the two
13 4.2.1 Macro-Invertebrates
original transformers at Piripaua Power Station were replaced
14 4.2.2 Waikaretaheke River Ecologial Assessment Below Piripaua
during the reporting period. This was a massive undertaking
14 4.2.3 Waikaretaheke River Trout
with the new units sourced from Korea. A multitude of other
14 4.2.4 Tune (eel) Migration Programmes
work was also undertaken during the four month outage (see
16 4.3 Water Quality
Section 5.1.3 for details).
16 4.3.1 Routine Monitoring
16 4.4 Sediment (Erosion, Transport and Deposition) Tuna Migration Programme A record number of elvers (32,984)
17 4.5 Recreation and Tourism were captured below Piripaua Power Station and transferred
17 4.5.1 Piripaua Power Station to upstream habitats. Planning is also well underway to install
17 4.5.2 Whakamarino Dam a migrant tuna by-pass which will provide a safe passage for
18 05 SCHEME-WIDE OUTCOMES migrant tuna out of Lake Whakamarino into the Waikaretaheke
19 5.1 Maintenance Activities River. The by-pass will be completed in the next reporting
19 5.1.1 Scheme-wide Maintenance Consent period (see Section 4.2.4 for details).
19 5.1.2 Piripaua Intake Weed Accumulation
19
20
5.1.3
5.1.4
Piripaua Transformer Upgrade
Waikaremoana Transmission Condition Assessment
ABBREVIATIONS
20 5.2 Sports Fish and Habitat Enhancement Fund AER Annual Environmental Report
21 5.3 Dam Safety CSR Comprehensive Safety Review
21 5.4 Oil Spill Response DOC Department of Conservation
21 5.5 Public Complaints ECNZ Electricity Corporation of New Zealand
21 5.6 Publicly Available Hydrology Information EMS Environmental Management System
EPT Ephemeroptera, Plecoptera, and Trichoptera
22 06 COMMUNITY & ENVIRONMENTAL INITIATIVES (the three insect orders commonly used to test water quality)
23 6.1 Lake Waikaremoana Hapu GPS Global Positioning System
Restoration Trust Partnership GWh Gigawatt hour
23 6.2 Whio Forever HBCC Hawkes Bay Canoe Club
24 6.3 Waikareiti Biodiversity Project HBRC Hawkes Bay Regional Council
25 6.4 Waimako Marae DIY LWHRT Lake Waikaremoana Hapu Restoration Trust
25 6.5 Lake Waikaremoana Challenge masl meters above sea level – Moturiki Datum
26 6.6 Aquatic Weeds MPI Ministry of Primary Industries
MVA Megavolt Amp
27 07 KEY OBJECTIVES
MW Megawatt
28 7.1 Review of Key Objectives for 2012-13
NIWA National Institute of Water and Atmospheric Research
28 7.2 Key Objectives for 2013-14
NZTA New Zealand Transport Authority
29 08 REFERENCES QMCI Quantitative Macro-invertebrate Community Index
RCMS Resource Consent Management System
SPI Submerged Plant Indicators
WERP Waikaremoana Ecological Restoration Programme
WPS Waikaremoana Power Scheme
WSFF Waikaremoana Sports Fish and Habitat Enhancement Fund
Front cover photo: Diver working on Number 2 siphon - Onepoto Siphon,
Lake Waikaremoana, 1946.
Back cover photo: Transporting pipe during construction of the
Waikaremoana Power Scheme, 1946
01 INTRODUCTION The first five-yearly review was in 2004 and at this time Genesis
Energy sought changes to the monitoring and reporting conditions
Nau mai haere mai ki tenei Ripoata Taiao e pa ana ki te mahi to allow for more targeted monitoring programmes at Lake
hihiko mo tenei rohe o Waikaremoana. Waikaremoana and on the Waikaretaheke River. The Hawkes Bay
Regional Council (HBRC) adopted the recommendations and these
Welcome to the 2012-2013 Annual Environmental Report (AER)
were incorporated into the Lake Waikaremoana Monitoring Plan
for the Waikaremoana Power Scheme (WPS). The purpose of this
and the Waikaretaheke River Monitoring Plan.
report is to update communities and stakeholders on the wide
range of activities which occurred at the WPS between July 2012 The second opportunity for a five-yearly review occurred in 2009;
and June 2013. It is the seventh AER for the WPS and follows from however a review of the resource consents was not requested by
previous year’s reporting. This report will: Genesis Energy nor undertaken by HBRC.
provide an overview of resource consent compliance Up until February 2013, resource consents for routine
at the WPS; maintenance activities around the WPS were generally applied
provide an update on monitoring and research programmes; for on an as-required basis. However during the reporting
report back on key projects; period, scheme-wide resource consents to undertake various
report on community and environmental initiatives; and routine maintenance activities at the WPS were granted by
define environmental objectives for the next 12 months. HBRC. Similar maintenance consents have been in place at the
Tongariro Power Scheme since 2004 and they have proven to be an
Genesis Energy aims to be accessible to the public, to address
efficient mechanism to undertake routine maintenance activities,
issues as they arise and to develop closer working relationships
whilst effectively managing the effects of the activities on the
within the communities within which it operates.
environment (see Section 5.1.1).
1.1 DOCUMENT OVERVIEW
1.3 HOW TO USE THIS DOCUMENT
Genesis Energy produces a suite of reports and other
This report documents environmental outcomes based on two key
documentation on its activities each year (Figure 1). These include
geographical features:
detailed technical reports, audit reports and various reporting
requirements to stakeholders. They address specific issues at a Lake Waikaremoana;
site/local level. Waikaretaheke River.
The Company’s Annual Report details Genesis Energy’s The report also provides information for:
performance as a company and sets objectives for the coming year.
Scheme-wide Outcomes;
Community and Environmental Initiatives.
‘Bold text like this’ will help you to find your way around the
report. This identifies the parts of the report that relate to specific
resource consent conditions.
Consent Description Consent # (condition)
‘Orange text like this’ throughout the report provides useful
background information on specific issues.
1.4 GENESIS ENERGY’S APPROACH
TO ENVIRONMENTAL MANAGEMENT
1.4.1 GENESIS ENERGY’S VALUES
Genesis Energy’s four core values define the way things are done
at Genesis Energy. They are the actions and behaviours which
help contribute to the success of the company.
Genesis Energy’s Values are:
FIGURE 1 // Report hierarchy at Genesis Energy.
Respect – We treat people and places as we would
wish to be treated
This AER bridges the gap between site specific reporting and Drive – We achieve with energy, courage and commitment
the company’s Annual Report. It provides an overview of all Imagine – We challenge today and change tomorrow
environmental and stakeholder activities relating to the WPS. It Support – We work together, take responsibility and have fun
does not overview company strategy or performance (refer to the Genesis Energy’s intent is to become the preferred provider of
Annual Report for this information) or provide extensive detailed energy in New Zealand. We will achieve this by:
WAIKAREMOANA // 13
information on all monitoring programmes and initiatives undertaken
(refer to specific technical reports listed in the references). Delivering efficient service and smart solutions to customers;
Optimising the performance of our generation portfolio;
More information about Genesis Energy, including an electronic ‘Living’ our values; and
copy of this document, can be found on the website Operating in a way that is safe and healthy for our people,
www.genesisenergy.co.nz our customers, our communities and the environment.
1.2 RESOURCE CONSENT PROCESS OVERVIEW 1.4.2 ENVIRONMENTAL MANAGEMENT SYSTEM
Resource consents for the on-going operation of the WPS were Genesis Energy has an Environmental Management System
granted in November 1998. This followed a period of intensive (EMS) which ensures that environmental and social awareness
consultation, technical assessments, recommendations and are core to the operation of the Company. The EMS sets out the
review via a formal consultative group, and through one on one Company’s values in respect of environmental and stakeholder
consultation with affected and interested parties. The consultation management, and clearly states its commitment to compliance
process addressed numerous issues and in most cases outcomes with all environmental legislation.
were agreed. Forty-five resource consents were granted for a
02
term of 35 years, subject to a range of conditions, including a five-
yearly review.
Genesis Energy’s Environmental Values are: Data collected by the hydrology team is audited by an independent
third party on at least an annual basis to maintain a high level of
Act with integrity at all times. transparency and external credibility and ensure data is being
Foster close relationships with the community and collected and processed to a high standard.
stakeholders, so that their views can be incorporated into the
environmental decision-making processes. 1.5 FEEDBACK
Acknowledge that our activities affect both the environment
and the communities within which we operate. Genesis Energy has worked to make this report informative and
Respect the role of tangata whenua as kaitiaki of the natural easy to understand. Your feedback is welcome on both content
resources and taonga within their rohe. and layout. Contact details are as follows:
Investigate to better understand the nature of the Renewable Energy – Tokaanu Power Station
environmental effects – and share this information with the State Highway 47
community and stakeholders. Private Bag 36, TURANGI 3353
Seek environmental improvements in all aspects Phone (07) 384 7200
of our business.
During the reporting period Genesis Energy began a review of its
EMS. This is to ensure that it encompasses the number of different
business systems used by the environmental teams and to ensure
that they are integrated with other core business systems, for
example the Resource Consent Management System. The review
is also checking that the EMS applies to all activities involving the
use of natural and physical resources and the environment, from
the conceptual stage of any project through to normal operational
activities of Genesis Energy. The review will be completed in the
2013/14 reporting period.
1.4.3 RESOURCE CONSENT MANAGEMENT SYSTEM
To help manage compliance across all generation sites, Genesis
Energy has developed a Resource Consent Management System
(RCMS). This system holds all information relating to resource
consents, third party agreements, and permitted activities,
and defines, prompts and monitors actions required by their
conditions, and reports on the status of these. The purpose of the
RCMS is to ensure that Genesis Energy manages its statutory and
stakeholder obligations effectively and that essential requirements
are not overlooked.
All Genesis Energy staff can access the RCMS through the
company’s intranet but only designated administrators within the
Environmental Team can make changes and update/sign off tasks,
or view potentially confidential information contained within third
party agreements.
An internal RCMS and environmental compliance audit is
undertaken on an annual basis at selected generation sites.
The purpose of the audit is to ensure the correct procedures are
being followed and identify any improvements that could be made
to RCMS systems or processes to best achieve 100% compliance.
A RCMS and environmental compliance audit for the WPS is
scheduled for July 2013 and will be reported on in the AER
reporting period 2013/14. During the reporting period, required
improvements to the RCMS were identified including enhanced
ENVIRONMENTAL REPORT // 13
reporting functionality and ensuring that the system is more user-
friendly. A project is planned to incorporate these changes in the
RCMS in the 2013/14 reporting period.
1.4.4 HYDROLOGY
Genesis Energy has an extensive hydrology monitoring network
around the WPS. A variety of flow, water level, water quality and
rainfall data is collected in real-time and telemetered near real-
time. This information is sent to Genesis Energy’s Renewable
Energy Control Centre, located near Turangi, together with a range
of plant and market information.
During the reporting period the hydrology team has put an
extensive amount of work into improving the monitoring network
which has resulted in a high level of compliance along with more
efficient operation of plant for Genesis Energy. An example of an
upgrade that occurred during the reporting period was switching
the back-up data communications from radio to a cellphone
network which provide a more reliable, accurate and complete
records and are part of a holistic approach towards improving
the hydrological network. The hydrology team has supported the
03
implementation of key environmental projects with their technical
expertise and ability to share this with stakeholders.
02
WAIKAREMOANA
POWER SCHEME
WAIKAREMOANA // 13
04
02 WAIKAREMOANA POWER SCHEME
TABLE 1 // Average monthly inflows into Lake Waikaremoana during
The Waikaremoana Power Scheme (WPS) is located within and the reporting period.
adjacent to Te Urewera National Park in the northern Hawkes Bay
Region. The location and features of the scheme are shown on the Month 2012-13 Long Term Percent of
map inside the back cover. Average average Inflow Average (%)
Inflow (1930 - present)
The potential for power generation from the outflow of Lake (m3/s) (m3/s)
Waikaremoana was recognised in the 19th century (Natusch,
July 24.9 28.07 89%
1992) and three power stations were commissioned between 1929
and 1948. The WPS uses water from Lake Waikaremoana and the August 20.15 25.53 79%
Waikaretaheke River and a number of its tributaries to generate
September 17.87 21.12 85%
electricity at three hydroelectric power stations – Kaitawa (36
megawatts [MW]), Tuai (60 MW) and Piripaua (42 MW). Water is October 12.45 17.38 72%
taken from Lake Waikaremoana via tunnels at Onepoto Bay and is November 7.64 13.67 56%
passed through Kaitawa Power Station before being discharged
into Lake Kaitawa. It is then passed through Tuai Power Station December 6.32 11.29 56%
and discharged into Lake Whakamarino. From here, a further January 4.32 10.12 43%
tunnel and penstocks carry the water to Piripaua Power Station
February 1.88 10.91 17%
before it is discharged back into the Waikaretaheke River, the
natural outlet of Lake Waikaremoana. March 2.19 12.37 18%
The generating plant has undergone major refurbishment over April 4.79 15.27 31%
the past twenty years and the scheme’s generation capacity has May 10.88 20.13 54%
increased from 124 to 138 MW. Operation of the WPS depends on
June 19.88 23.56 84%
the demand for electricity and the availability of water. Electricity
from the WPS feeds into the national electricity grid and assists in Annual Average 11.2 17.5 64%
maintaining voltage levels on the transmission system.
Supply of electricity to the East Coast from the WPS is important
for two reasons. Firstly, the generators at Waikaremoana provide
voltage support for the Gisborne and Tokomaru Bay Transpower
transmission circuits. Secondly, the close proximity of the WPS
to Gisborne results in lower transmission losses, which reduces
the need for generation overall. The WPS is also ideally situated
to provide power to the East Cape area when the East Cape loses
connection to the national grid.
2.1 OPERATING THE WAIKAREMOANA POWER SCHEME
The WPS is operated remotely from Genesis Energy’s Renewable
Energy Control Centre, which is part of the Tongariro Power
Scheme near Turangi. A 24/7 Generation Control team runs the
WPS as effectively and efficiently as possible using a variety of
flow, water level and rainfall data, as well as a range of plant and
market information to optimise electricity generation revenue
requirements while maintaining compliance with resource consent
conditions and operating within the electricity market rules. A
complex operational control system that underwent a significant
FIGURE 2 // Modelled inflows and rainfall for Lake Waikaremoana
upgrade in 2010 assists the operations team, providing details on
during the reporting period.
all aspects of the scheme, enabling remote control and alerting
the operators when various parameters trend outside of their
standard operating limits (including resource consent limits).
The WPS generated a total of 249 Gigawatt hours (GWh) of
There is a full maintenance team at the WPS with roaming
electricity (Table 2), again significantly below the long-term
ENVIRONMENTAL REPORT // 13
Controllers on site. These Controllers are available 24/7 to fix
average (approximately 450 GWh). This reflects the weather
faults or defects as they arise.
conditions during this reporting period as well as significant
2.2 CLIMATE AND POWER GENERATION outages which took place, such as the Piripaua transformer
upgrade (see Section 5.1.3), which reduced the generation capacity
The Lake Waikaremoana catchment had below average rainfall of the scheme significantly.
over the reporting period. Inflows were steady at just below the
long-term average during July to October 2012 (Table 1), however, Based on an average figure of electricity consumption per
this dropped away significantly through the summer months as household of 7,760 kWh/yr (Ministry of Economic Development,
the East Coast entered into a period of drought. The combined 2012; p121) the 249 GWh produced by the WPS in the reporting
average inflows for February and March were the lowest on record period was enough electricity to power the annual demand of
since 1982. Inflows for the year overall were 64% of the long-term approximately 32,000 households.
average (1930 – present).
There were no significant inflow events during the reporting period TABLE 2 // Waikaremoana Power Scheme generation
during the reporting period.
(Figure 2) and the lake was able to be maintained between 26%
and 65% full.
Site Generation (GWh)
The total rainfall recorded at Onepoto for the reporting period was
Kaitawa 36
1,487 mm, well below the long-term average at this site (1,939 mm).
July 2012 had the highest monthly rainfall with 245.8 mm while Tuai 130
February 2013 had the lowest monthly rainfall with just 59.6 mm. Piripaua 83
05
Total 249
06 WAIKAREMOANA // 13
03
LAKE
WAIKAREMOANA
03 LAKE WAIKAREMOANA event-driven monitoring to assess the impact of lake
level excursions outside of the operating range on shoreline
Lake Waikaremoana was created approximately 2200 years ago morphology and vegetation;
by a massive landslide that dammed the Waikaretaheke River. a third party agreement with DOC with a focus on ecological
The landslide created a steep natural dam face at the head of the enhancement on the shore of Lake Waikaremoana;
valley down which the Waikaretaheke River once flowed. Below a third party agreement with Fish and Game Council of
this natural dam, the Waikaretaheke River was fed by water New Zealand to increase angler opportunities in the
leaking through the dam. Hawkes Bay Region.
In association with DOC and the Royal Forest and Bird
Lake Waikaremoana is the primary hydro-storage lake for the
Protection Society, Genesis Energy undertook a project to
Waikaremoana Power Scheme (WPS). The lake has a surface
enhance the Onepoto Gatehouse area (a main access point
area of approximately 53 km2 and an operating range of three
for the Great Walk track) by planting native species and
metres, from 580.29 to 583.29 masl. In 1946 the level of Lake
erecting information panels.
Waikaremoana was lowered by five metres to facilitate the
operation of the WPS (Figure 3). The natural lake level range was 3.1 HYDROLOGY
approximately seven metres.
Lake Waikaremoana has a normal operating range from 580.29
to 583.29 masl. Genesis Energy must release a controlled
discharge from the lake (Table 3) if the maximum lake level is
reached or exceeded.
Lake Waikaremoana HBRC WP982030Mc (3,4)
During the reporting period a variation was obtained to resource
consent WP982030Mc as part of the scheme-wide maintenance
consent acquisition (see Section 5.1.1) to allow for temporary
cessation of controlled discharge for maintenance purposes,
for example to allow for the safe removal of obstructions from
intake screens.
TABLE 3 // Controlled discharge rates from Lake Waikaremoana
when lake level exceeds 583.29 masl.
Lake level (m) Controlled discharge (m3/s)
583.29 No Controlled Release
583.29 43
FIGURE 3 // Water level at Lake Waikaremoana
(1929–30 June 2013). 583.49 47
583.69 51
584.09 55
Lowering the lake level and narrowing the lake level range
changed the energy of waves acting on the shoreline. Lake Genesis Energy constantly monitors the level of Lake
Waikaremoana has always experienced significant fluctuations Waikaremoana. A three hour average lake level is used to assess
in level, and these fluctuations had significant effects on the lake level compliance. This average helps to remove sieche and
character of the pre-1946 shoreline (large eroded shoreline scarps wave effects from the lake level record. Figure 4 shows the level
are evident in many places). Some on-going erosion and change of Lake Waikaremoana for the reporting period.
is entirely natural, even though the lake is now managed within a
three metre operating range.
Lowering the lake level directly affected the shoreline, creating
large, flat, unvegetated areas. These have subsequently been
utilised for assets such as the campground at Home Bay and
related sewage ponds (which have now been relocated away from
ENVIRONMENTAL REPORT // 13
the lake shore), Department of Conservation (DOC) huts and parts
of the Great Walk track.
After the lake level was lowered, attempts were made to seal
leaks in the natural dam by constructing rock filter blankets in the
lakebed at Te Wharawhara Bay. Combined with the lake lowering,
sealing the lake reduced leakage through the natural dam from
approximately 17 cubic metres per second (m3/s) to 5 m3/s,
making more water available for electricity generation.
Key outcomes of the resource consents process in 1998 and the
subsequent change of resource consent were:
a three metre operating range for the lake, with specific
conditions controlling discharges above and below the FIGURE 4 // Level of Lake Waikaremoana for the reporting period.
operating range;
preparation and implementation of the Lake Waikaremoana
Monitoring Plan which includes information on:
hydrology; Lake level compliance for Lake Waikaremoana for the reporting
terrestrial shoreline vegetation; period is detailed in Table 4. The lake did not exceed the
shoreline morphology; maximum control level during the reporting period.
07
littoral ecology;
brown trout.
The key purpose of shoreline vegetation monitoring is to assess
TABLE 4 // Lake Waikaremoana level compliance during the effects of the lake level management regime on terrestrial
the reporting period. vegetation structure and development.
Parameter Value (masl) Compliance (%) Consent Number A total of 100 vegetation transects and/or photo-points have been
(condition) established around the Waikaremoana shoreline since 1999.
These monitoring sites represent a full range of shoreline profiles,
Minimum level 580.29 100 WP982030MB (3)
substrates and habitat types. Shoreline vegetation transects are
Maximum level 583.29 100 WP982030MB (3) surveyed every five years and photo-points are surveyed annually.
They provide baseline data which enable detection of even minor
Outflows from Lake Waikaremoana are limited by the permeability changes in vegetation related to lake level variation.
of the dam wall and the flow that can be taken through Genesis Monitoring since 1999 indicates that fluctuations in lake level
Energy structures. Genesis Energy can only take water from within the three metre operating range have resulted in detectable
Lake Waikaremoana via a siphon system, through Kaitawa Power changes to the terrestrial vegetation. The ecological effect of these
Station, or via a spillway (at very high lake levels). The maximum changes, however, is minor and is comparable to that which would
rate of take through each structure is related to the design of the occur naturally on similar lake shorelines. A lake level regime
system. The design criteria of these structures are defined in reflecting the natural range of over seven metres would result in
resource consents. There have been no changes to the structures far more dramatic changes (Single & Shaw, 2005).
during the reporting period.
Lake Waikaremoana HBRC WP982010Ta; The key driver of vegetation change at Lake Waikaremoana is the
HBRC WP982001Ta; length of time that the lake spends above or below certain levels.
HBRC WP982003Ta Prolonged high lake levels enable turf communities to establish
at high elevations but will also kill terrestrial species that cannot
3.1.1 LEVEL TRENDS AT LAKE WAIKAREMOANA
tolerate prolonged submergence. Prolonged low lake levels
Pre-construction of the power scheme, lake levels were generally have the opposite effect: turf communities dry out and terrestrial
high heading into summer, reducing during summer and autumn species are able to establish at lower elevation, where they are at
and increasing during winter and spring. Lake Waikaremoana is risk of submergence when the level increases again.
managed to reflect this natural cycle. During the reporting period
In 2005, in line with a change of resource consent, the original
the lake level mimicked this natural pattern of variability closely
monitoring programme (Shaw, 1998) was formally revised and
by rising to its highest level in early summer and dropping steadily
vegetation and shoreline morphology monitoring became more
through to late autumn. Since late April the lake has been rising
integrated (Single 2005; Single and Shaw 2005).
with early winter inflows and as a result of reduced water usage
Lake Waikaremoana HBRC WP982030Mb (11-12)
due to maintenance projects such as the Piripaua Transformer
Upgrade (see Section 5.1.3) (Figure 5). The annual Lake Waikaremoana shoreline inspection, involving
Lake Waikaremoana HBRC WP982030Mb (4) circumnavigation of the entire shoreline, rephotographing, and
evaluating all photo-points, was undertaken in February 2013.
Details of the key findings are reported by Wildland Consultants
Ltd (Wildlands, 2013).
Changes to the shoreline vegetation and profiles in the reporting
period were very minor, and no change was evident for 88% of
regularly monitored sites. There were very minor physical changes
to the shoreline. Minor changes in the distribution of shoreline
species was related to their tolerance of submergence. Minor
changes occurred locally on the following four shoreline types:
Stream Sedimentary Fans;
Wave Cut Terrace with Scarp;
Wave Cut Terrace - Gentle Slope;
Rock Platform or Pavement Overlain with Wave Cut Terrace.
No change was noted on the following six shoreline types:
Sandstone boulders grading back into wave cut terrace (four sites);
Rock headland;
Pocket beach;
FIGURE 5 // Lake Waikaremoana inflows and level during the Blocks boulders;
reporting period. Cliffs;
Narrow sandy beach.
WAIKAREMOANA // 13
Wildland Consultants advise that ensuring that high lake levels
3.2 ECOSYSTEMS AND WATER QUALITY are attained from time-to-time (around the top of the operating
range and just above) should be seen as a positive influence
The Lake Waikaremoana Monitoring Plan defines the type and on lakeshore ecology. In ecological terms, there are no new
frequency of monitoring to be undertaken on Lake Waikaremoana. observations of changes or developments on the shoreline that
This section describes the current programmes from ecosystem give cause for any concern.
and water quality perspectives.
The next annual photo-point inspections will be undertaken in
3.2.1 TERRESTRIAL VEGETATION March 2014, and the next five-yearly vegetation transect re-
The natural vegetation around the shore of Lake Waikaremoana is measurement is due in March 2016.
a significant feature of the lake. Much of the post-1946 exposed 3.2.2 AQUATIC VEGETATION
shoreline is now covered with indigenous vegetation, with
localised areas of exotic grassland, particularly on the more fertile Lake Waikaremoana has high native aquatic plant species
old river delta shorelines. diversity and contains the best remaining example of native
aquatic vegetation assemblages in a large, deep, clear lake in
08
the North Island. Aquatic plants (macrophytes) provide substratefor epiphytic algae, upon which many littoral (shallow shoreline) 3.2.3 TROUT MONITORING
macro-invertebrates feed. As such, maintenance of the littoral
zone is important to the productivity and ecology of the lake. Brown and rainbow trout were introduced into Lake Waikaremoana
Changes in aquatic macrophyte communities may result from in 1896 for recreational angling. The resultant fishery is now
prolonged periods of lowered water levels which have the considered to be of national importance. During summer, brown
potential to expose shallow-water plant communities. Narrowing trout live in the lake’s littoral zone.
the overall lake level operating range also has the potential to
A key feature of the Lake Waikaremoana brown trout fishery is the
change the macrophyte species composition. Monitoring of these
opportunity for anglers to stalk around the shoreline spotting and
communities is, therefore, an important part of lake management.
fishing to brown trout feeding in the shallow lake margins. Lake
Lake Waikaremoana HBRC WP982030Mb (15-16)
levels can affect this angling opportunity by altering the amount
The littoral aquatic macrophyte vegetation of Lake Waikaremoana of shoreline physically accessible during spring and summer.
is monitored every five years along 17 transects within the lake. High lake levels restrict the number of shoreline sites available
Prior to this year, the last survey was undertaken in February for angling and accessibility for moving between fishing sites
2008. During the reporting period the 17 transects were re- as there is limited room to wade around the shoreline between
surveyed and the depth ranges, coverage, and heights of each the water’s edge and the vegetation. There is also very limited
macrophyte species recorded. Details of the key findings are room for fly fishermen to back-cast: the curtain of vegetation
reported by NIWA (Wells & Winton, 2013). close to the water’s edge limiting the amount of fishable water
for this technique. Fewer places to fish result in more frequent
Twenty-two species of submerged macrophytes were recorded in encounters with other anglers, more fishing pressure at the fewer
2013 with native plants most prevalent. The three main macrophyte fishable sites and consequently lower catch rates. In the past,
communities present in the lake were: the amphibious short Genesis Energy was required to quantify the change in shore-
shallow-water community, tall vascular community and deeper based angling opportunity as a result of lake level changes.
charophyte community. Elodea was the most abundant exotic This consent requirement was completed between November
species and dominated the tall growing vascular community in 2008 and March 2010 and was reported in the 2009/10 Annual
sheltered sites, such as Home Bay, but mostly co-existed with Environmental Report for the Waikaremoana Power Scheme
native species rather than displacing them in the main body of (Genesis Energy, 2010).
the lake. Lagarosiphon was not found on any of the profiles but is
present in the lake and the subject of an eradication programme Lake level manipulation also has the potential to affect the littoral
supported by Genesis Energy (see Section 6.5). ecosystem and therefore, could adversely affect both juvenile
trout habitat and adult growth rates. Between 2000 and 2005, a
Overall any differences compared to previous surveys were small brown trout monitoring programme was undertaken to assess
with the lake vegetation continuing to occupy more than a 20 m any potential adverse effects of the current operating regime
depth range (Figure 6), where conditions (such as slope, substrate (Pitkethley and Kusabs, 2005). Brown trout population estimates
and exposure) were favourable, with similar species composition. for Lake Waikaremoana were originally indexed by counting
Continued high values for cover, species diversity and depth range spawning adult trout in the Waiotukupuna Stream, one of the
of lake vegetation indicated no change in lake ecological condition. major spawning streams. However, these estimates were not
Lake SPI (Submerged Plant Indicators) indices also confirmed the considered satisfactory and a 5-yearly intensive trapping operation
stability of lake condition over the last 10 years with no significant of spawning trout on the Waiotukupuna Stream has been
changes between consecutive surveys. Lake Waikaremoana is instigated in its place.
categorised as being in a high ecological condition with a Lake SPI Lake Waikaremoana HBRC WP982030Mb (17-18)
Index of 74%. This reflected the very high floristic values in the
lake (Native Condition Index, 77%) and low impact from invasive The Waiotukupuna Stream fish trap was operated for a minimum
species (Invasive Impact Index, 26%). of 10 nights per month over the 2009 winter period (May – August).
The next five-yearly assessment of trout populations is due in the
As there is a close relationship between aquatic plants and winter of 2014.
dependent macroinvertebrates, the continued good status of the
lake vegetation indicates that the macroinvertebrate community 3.2.4 ECOLOGICAL RESTORATION PROGRAMME
is likely to be healthy. Wells & Winton (2013) conclude that fish
During the resource consents process many complex issues were
dependent on invertebrates as a food source would not have been
raised and worked through with the Department of Conservation
affected by lake level fluctuations disrupting their food source.
(DOC). Some of these issues were addressed through consent
The next littoral aquatic macrophyte vegetation survey is due in conditions and the development of monitoring programmes;
February 2018. others were mitigated via a 10-year agreement with DOC.
Under this agreement, known as the Waikaremoana Ecological
ENVIRONMENTAL REPORT // 13
Restoration Programme (WERP), Genesis Energy provided funding
to DOC for ecological enhancement around the shore of the lake.
The original focus of WERP was to help secure a viable kiwi
population on the Puketukutuku Peninsula. Over time,
management of the kiwi programme on Puketukutuku Peninsula
transferred to the Lake Waikaremoana Hapu Restoration
Trust (LWHRT) and their increasing contribution to the kiwi
programme allowed DOC, with the LWHRT’s support, to focus on
other threatened species such as: whio (blue duck), ngutukaka
(kaka-beak), Powelliphanta snails, mistletoe and Dactylantus
(wood rose). The WERP agreement with DOC concluded in
2008, although Genesis Energy continues to support the kiwi
programme via an agreement with the Lake Waikaremoana Hapu
Restoration Trust (see Section 6.1).
While the original WERP agreement has now expired, Genesis
Energy continues to work with DOC staff from the Bay of Plenty/
East Coast Conservancy and tangata whenua on a new Genesis
FIGURE 6 // Bottom limit of the charophyte community at Site 9,
Energy sponsored biodiversity management project in the Lake
Wairau Arm, 21 m deep.
Waikareiti area (see Section 6.3).
093.3 SEDIMENT (EROSION, TRANSPORT AND DEPOSITION)
The sedimentary geology of the Lake Waikaremoana shoreline is
a significant natural feature. The Lake Waikaremoana Monitoring
Plan has been developed in part to assess the effects of the lake
level management regime on the structure and development of
shoreline landforms and erosion patterns.
Lowering the lake level in the 1940’s exposed large flat areas of
soft delta-sediment shorelines. These have subsequently been
used as sites for huts, tracks, camping grounds, sewage ponds
and other recreational and tourism assets. Shore change has
created hazards at some of these sites. Erosion, in particular,
threatens the viability of the assets and impacts on use of the
shoreline resource.
In 1999, Allan et al., developed an annual monitoring programme
which used a network of profiles and photo-points to assess
shoreline change and to determine the adequacy of existing
erosion protection works, and set timeframes for future erosion FIGURE 7 // Photo shows stabilisation of previously eroding old
hazard management. This programme was formally revised in lake bed deposit at Home Bay (Photo: Shore Processes and
2005 and incorporated into the Lake Waikaremoana Monitoring Management Ltd)
Plan. A significant change was the integration of DOC’s assets at
high erosion risk sites with the shoreline vegetation and erosion
monitoring programmes (Single 2005; Single and Shaw 2005). The next annual inspection and photo-point survey is due in
March 2014, while the next shoreline profile transect resurvey is
The current comprehensive monitoring network is based on a
scheduled for 2016. This survey date will coincide with the five-
combination of beach profile and differential Global Positioning
yearly vegetation survey.
System (GPS) surveys, covering sites established in 1999–2000.
New sites were also established between 2004 and 2007. Annual 3.3.1 EVENT-DRIVEN MONITORING
photo-point records compliment five-yearly field transect
measurements, which are designed to assess: Lake Waikaremoana has a large catchment and a restricted outlet
and lake levels can rise very rapidly following heavy rainfall.
changes in profile form over time; Vegetation within the 3 m operating range experiences dramatic
the stability of the shoreline; changes, depending on whether it is submerged, and for how long.
rates of shoreline advance and retreat; The shoreline substrates also experience dramatic changes in
changes in the position or patterns of shoreline contours; moisture levels and wave environments in relation to the degree
predictions of expected future shoreline changes; of inundation.
measurement of erosion rates on mudstone benches. Lake Waikaremoana HBRC WP982030Mb (11-14)
Monitoring identifies the magnitude and rates of shore change Event-driven monitoring is required when lake levels exceed
around the lake for different shore types and for shores 583.29 masl or go below 580.29 masl for more than seven
with different wave exposure, and it will continue to provide consecutive days. Event driven monitoring was not required during
benchmarks for future change. the reporting period.
Changes during the monitoring period 1999–2005 occurred to
beaches, soft shores and mudstone benches. Variations between
annual surveys reflected the characteristics of wind, wave and water
level influences during the period between surveys. Overall, the
magnitude of change at Lake Waikaremoana is comparable to or
less than that measured on other New Zealand lakes (Single, 2005).
A Shoreline Hazard Management Report was also produced in
2010 (Single et al, 2010) and forwarded to DOC, Hawkes Bay
Regional Council and to local tangata whenua representatives.
The report presents information for managing the risk posed to
activities and assets around the shore of Lake Waikaremoana by
lake level changes. This report is a valuable resource to assist
future asset management on the Lake Waikaremoana shoreline.
Lake Waikaremoana HBRC WP982030Mb (13-14)
The annual Lake Waikaremoana shoreline inspection, involving
WAIKAREMOANA // 13
circumnavigation of the entire shoreline, rephotographing, and
evaluating all photo-points, was undertaken in February 2013.
Details of the key findings are reported by Shore Processes and
Management Ltd (Single, 2013).
The 2013 inspection of the shoreline of Lake Waikaremoana and
comparison to the photographic record showed no significant
physical shoreline changes at any of the monitored sites, nor on
other sections of the shore (Figure 7). There was no evidence of
water level or wave events significantly modifying or adjusting
the beaches. However mudstone shores developed friable shale
covering of the surface during the summer. This was more evident
on north facing shores.
10RIVER
WAIKARETAHEKE
11 ENVIRONMENTAL REPORT // 13
0404 WAIKARETAHEKE RIVER
The Waikaretaheke River is the natural outlet from Lake
Waikaremoana. Below the lake outlet, the river has cut into the
landslide debris creating a very steep, incised and fast-flowing
river system.
Damming the natural outlet, sealing spring leaks and creating
lakes for the purposes of power generation has modified the
upper Waikaretaheke River catchment. The river’s two man-
made lakes, Kaitawa and Whakamarino, have become renowned
trout fisheries: Lake Whakamarino, in particular, produces high
numbers of very large trout.
A change of resource consent in 2005 sought a more focused
and targeted monitoring programme for the Waikaretaheke
River, which is encompassed within the Waikaretaheke River
Monitoring Plan. The change of resource consent also allows for
improvements to the monitoring programmes to be made as more
information becomes available. FIGURE 8 // Lake Kaitawa level during the reporting period.
Key outcomes of the 1998 resource consents process and the
subsequent change of resource consent were:
a 3.4 m operating range for Lake Kaitawa and a 1.8 m range
for Lake Whakamarino; During the reporting period a variation was obtained to resource
a requirement to measure and record the amount of flow consent WP982121Mb as part of the scheme-wide maintenance
in the Waikaretaheke River and the three power stations consent acquisition (see Section 5.1.1) to allow for lowering
and to provide this data annually to the Hawkes Bay the level of water in Lake Kaitawa by up to 1 metre below
Regional Council; the minimum operating level for the purpose of undertaking
minimum flows of 25 l/s downstream of the Waikaretaheke maintenance and/or repair work. A number of conditions are
Diversion Structure and 5 l/s downstream of the associated with this resource consent including a requirement that
Whakamarino Dam; the lake level is not lowered during the month of October to avoid
a requirement to maintain the quality of water discharges the opening of the fishing season (including Labour Weekend).
from the Waikaremoana Power Scheme;
During the reporting period, Lake Kaitawa achieved a very high
an agreement with the New Zealand Recreational Canoeing
level of compliance (Table 5). Only one minor non-compliance
Association – now known as Whitewater NZ – to provide
occurred during the reporting period where, for a period of ten
recreational kayaking opportunities within the Waikaremoana
minutes on 10 October 2012, Lake Kaitawa dropped below its
Power Scheme;
Minimum Control Level as a result of a tripping at the Kaitawa
an agreement with Transit New Zealand – now known as the
Power Station. A thorough investigation was undertaken and
New Zealand Transport Authority (NZTA) – to monitor erosion
appropriate actions put in place to prevent this from reoccurring
in the Waikaretaheke River;
in the future.
an agreement with Federated Farmers to provide minimum
flows as a stock barrier downstream of Piripaua Power Station;
preparation and implementation of the Waikaretaheke River TABLE 5 // Lake Kaitawa level compliance during
Monitoring Plan that will include monitoring programmes for: the reporting period.
macroinvertebrates below the Waikaretaheke Parameter Value (masl) Compliance (%) Consent Number
Diversion Gates; (condition)
the effect of recreational releases on trout in the river;
an elver trap and upstream transfer programme; Minimum level 450.1 99.99 WP982121MA (3)
a mature eel downstream transfer programme; Maximum level 453.5 100 WP982121MA (3)
hydrology.
4.1.2 WAIKARETAHEKE RIVER FROM KAITAWA SPILLWAY
4.1 HYDROLOGY
TO LAKE WHAKAMARINO
4.1.1 LAKE KAITAWA
The damming and diversion of waters from the Waikaretaheke
Lake Kaitawa was formed following the construction of an earth River by the Waikaretaheke Diversion Structure have reduced the
dam and weir across the Waikaretaheke River in the mid-1930s, magnitude and variability of flows downstream, thereby reducing
converting a small spring-fed lake and wetland into a larger the amount of habitat available for aquatic flora and fauna.
storage reservoir. The water level was raised by approximately Investigations into invertebrate populations have shown that the
WAIKAREMOANA // 13
3 m, creating a lake with a surface area of approximately 6.1 numbers in the river below the diversion structure are lower
hectares. The lake is fed by water diverted from the Waikaretaheke than would naturally have occurred. A minimum flow of 25 l/s is
River and a number of springs that flow directly into the lake. released downstream of the Waikaretaheke Diversion Structure to
Lake Kaitawa HBRC WP982121Mb provide some suitable habitat for native flora and fauna.
Waikaretaheke River HBRC WP982320Mf (6, 8)
Lake Kaitawa is the headpond for Tuai Power Station. The
operating range of the lake is 3.4 m, from 450.1 to 453.5 masl To maintain the minimum flow of 25 l/s downstream of the
(Figure 8). Water for the Tuai Power Station is taken through the Waikaretaheke Diversion Structure, holes have been drilled
Tuai Intake, located on the eastern side of the lake, at a maximum through the gate to release the desired amount of water. Genesis
rate of up to 42 m3/s. There is no minimum flow requirement in the Energy staff check the holes weekly to ensure that they remain
Waikaretaheke River downstream of Lake Kaitawa, with seepage free of any blockages.
and spring flows creating flow only a short distance downstream.
Genesis Energy hydrology staff undertake quarterly flow
gaugings downstream of the diversion structure to demonstrate
compliance. All of the gauged flows for this reporting period were
above the minimum flows with full compliance being achieved.
12Genesis Energy is required to close the Waikaretaheke Diversion A minimum flow of at least 5 l/s is maintained in the
for two hours, whenever a flow of greater than 5 m³/s is spilled Kahuitangaroa Stream immediately downstream of Lake
from Lake Kaitawa down the Waikaretaheke River. Spill from Whakamarino. The minimum flow is based on leakage flow from
Lake Kaitawa is not permitted on the 1st of October, the first the drainage galleries within the dam. This flow is monitored
weekend after 1st October, or during Labour Weekend, to reduce three-monthly by Genesis Energy hydrology staff and was fully
discolouration in Lake Whakamarino during these important compliant during the reporting period.
angling periods.
4.1.4 WAIKARETAHEKE RIVER BELOW PIRIPAUA POWER STATION
This condition was not exercised during this reporting period.
Lake Kaitawa exceeded its Maximum Control Level only once During the consent process, farmers along the Waikaretaheke
during the year which resulted in a spill flow of only 3 m³/s. The River, downstream of Piripaua Power Station, raised concerns that
Waikaretaheke Diversion gate remained open as the flow did not the river did not provide an adequate stock barrier during times
exceed the 5 m³/s required to initiate this condition. of low flow from Piripaua Power Station. Following a number of
flow trials, Genesis Energy reached an agreement with Federated
4.1.3 LAKE WHAKAMARINO Farmers to provide a minimum flow from Piripaua Power Station
of 2 m3/s between 1 November and 31 March each year.
Lake Whakamarino was created following the construction
of an earth dam (which contains a spillway structure) across The seasonal minimum flow below Piripaua Power Station, as
the Kahuitangaroa Stream. The lake has a surface area of agreed with Federated Farmers, was largely met during the
approximately 29.8 hectares. Water for the Piripaua Power Station reporting period, except for four short periods between December
is taken through the Piripaua Intake, located on the south-eastern 2012 and March 2013. On these occasions there was no flow
side of Lake Whakamarino, at a maximum rate of up to 49 m3/s. through the Piripaua Power Station as a result of operational or
Below Whakamarino Dam a continuous minimum flow of maintenance issues. Stakeholders were notified of these events
5 l/s is maintained. and no issues were raised. The dates and durations of each event
Lake Whakamarino HBRC WP982420Mc (5) are listed in Table 7.
During the reporting period a variation was obtained to resource
consent WP9824020Md as part of the scheme-wide maintenance TABLE 7 // Flow periods below the agreed 2 m³/s flow downstream
of Piripaua Power Station.
consent acquisition (see Section 5.1.1) to allow for lowering
the level of water in Lake Whakamarino by up to 1 m below the
minimum operating level for the purpose of undertaking any Date Duration Minimum Flow Reason
maintenance and/or repair work. 18/12/12 4 hours 503 litres/sec Transpower
tripping at
Lake Whakamarino has a normal operating range of 1.8 m, Redclyffe
from 246.3 to 248.1 masl (Figure 9). There was one minor non-
compliance event during the reporting period which occurred 1/02/13 5.5 hours 404 litres/sec Wicket gate link
failure
on 29 April 2013 as a result of the lake dropping below the
minimum control level for 40 minutes (Table 6). During this 24/03/13 10 hours 438 litres/sec Transformer
time, the minimum level that the lake reached was recorded as Replacement
246.28 masl. The event was caused by an equipment fault that 27/03/13 5 hours 411 litres/sec Transformer
resulted in incorrect information being displayed at the Generation Replacement
Control Centre – an issue that was rectified as soon as it became
apparent. There were no adverse environmental or ecological 4.1.5 MAXIMUM FLOWS: WAIKARETAHEKE RIVER AND LAKES
effects caused by this event and no complaints were received. The WAIKAREMOANA, KAITAWA AND WHAKAMARINO
correct information is now displayed in the Control Centre.
Resource consents specify maximum flow limits, based on design
criteria, for several discharge control points (Table 8). There have
been no modifications to any of these control points and therefore
no alteration of their flow capacities.
4.2 AQUATIC ECOSYSTEMS AND WATER QUALITY
4.2.1 MACRO-INVERTEBRATES
Studies of macro-invertebrate communities have been undertaken
to assess the effect of reduced flows below the Waikaretaheke
ENVIRONMENTAL REPORT // 13
Diversion structure, down to the Mangaone Stream confluence
where flow recovery begins. Based on the results of five years of
data collected between 1999 and 2003, Scarsbrook and Bowman
(2003) concluded that the timing of flow releases down the natural
Waikaretaheke River channel was a more significant driver of
macro-invertebrate community composition than the level of
residual flow in the natural channel. Samples collected soon after
flushing flows had downstream communities similar to those
upstream, whereas samples collected after a long period without
FIGURE 9 // Lake Whakamarino level during the reporting period.
flushing flows had different assemblages to those expected in the
Waikaretaheke River.
Lake Whakamarino HBRC WP982420Mc (9)
Piripaua Power Station HBRC DP982510Wb (11)
Waikaretaheke River HBRC WP982320Mf (13)
TABLE 6 // Lake Whakamarino level compliance for
the reporting period. The Waikaretaheke Monitoring Plan requires regular assessment
of macro-invertebrate communities in the Waikaretaheke
Parameter Value (masl) Compliance (%) Consent Number downstream of the diversion structure. Macro invertebrate
(condition) data was last collected from the Waikaretaheke River by Tonkin
& Taylor in March/April 2009. Their recommendation was
Minimum level 246.3 99.99 WP982420MC (5)
that routine monitoring of macro invertebrate communities be
13
Maximum level 248.1 100 WP982420MC (5) continued at five-yearly intervals. This recommendation was
accepted by Hawkes Bay Regional Council in October 2009.
The next scheduled monitoring will occur in March/April 2014.TABLE 8 // Design capacities of discharge control points within the WPS.
Site Type Design Capacity l/s Consent No.
Kaitawa tunnels Discharge g/w and drainage water 80 DP982020W
Kaitawa weir drains Discharge to Waikaretaheke River 100 DP982111W
Kaitawa Power Station penstock main inlet valve Discharge to unnamed tributary 700 DP982114W
Kaitawa Power Station tailrace Take for cooling 110 WP982113T
Tuai Power Station Discharge 10 DP982220W
Waikaretaheke Diversion Canal Discharge to Waikaretaheke River 100 DP982323W
Piripaua Power Station cooling circuits and penstocks Discharge to Waikaretaheke River 100 DP982512W
Piripaua Power Station oil interceptor Discharge to Waikaretaheke River 15 DP982515W
Piripaua Power Station tailrace Take for cooling 110 WP982511T
Piripaua Tunnel large siphon Discharge to Waikaretaheke River 200 DP982501W
Piripaua Tunnel small siphon Discharge to an unnamed tributary of the 150 DP982503W
Waikaretaheke River
Tuai Outdoor Switchyard cooling water system Discharge to an unnamed tributary 11 DP982403W
Tuai Power Station cooling water system Discharge to Lake Whakamarino 100 DP982412W
Tuai Power Station oil interceptors Discharge to Lake Whakamarino 20 DP982413W
Tuai Outdoor Switchyard cooling water system No.1 Discharge to Kahutangaroa Stream 1.4 DP982414W
Tuai auxiliary turbines Discharge to Lake Whakamarino 400 DP982415W
4.2.2 WAIKARETAHEKE RIVER ECOLOGICAL The high quality of the in-stream habitat and predominance of EPT
ASSESSMENT BELOW PIRIPAUA taxa are likely to be key factors in the river supporting a healthy
trout population, with an excess of 100 medium to large trout per
In addition to the macro-invertebrate monitoring described above kilometre recorded by Fish & Game in October 2008 (Osborne, 2009).
in 4.2.1, Genesis Energy commissioned Freshwater Solutions
Ltd to undertake further investigations into the ecology of the 4.2.3 WAIKARETAHEKE RIVER TROUT
Waikaretaheke River below Piripaua Power Station. This work was
aimed at gaining a better understanding of the ecological system Between 1999 and 2001, trout populations in the Waikaretaheke
that has developed in the 4 km section of river below the power River were monitored by twice-yearly drift dives (May and
station under the current flow regime. Initial assessments were September) to determine whether recreational flow releases were
conducted in summer (February 2012), and further comparative impacting on trout numbers (Kusabs, 2002). The study found that:
assessments were undertaken during the reporting period in
the Waikaretaheke River below Piripaua supported moderate
winter (August 2012). The results are reported by Freshwater
densities of rainbow trout and low numbers of brown trout;
Solutions Ltd (Montgomerie, 2012).
recreational flow releases did not adversely affect trout
The flow regime on the Waikaretaheke River below Piripaua Power abundance in the upper Waikaretaheke River.
Station results in a variable flow ranging, potentially, between
Kusabs (2002) stated, however, that the long-term effects of the
1 and 45 m³/s and, typically, between 5 and 40 m³/s daily. This
flow releases on the trout population would only become apparent
section of river has a moderate gradient, is willow lined and
after 1 to 2 generations (3–6 years for rainbow trout and 4–8 years
bouldery in nature. The riverbed is typically 20 m wide with a
for brown trout). Consequently, the Waikaretaheke River Monitoring
permanently wetted channel of 15 – 18 m and a variable (temporal)
Plan recommends that five-yearly drift dives be carried out.
wetted zone typically of 1 to 3 m on each side of this permanently
Lake Whakamarino HBRC WP982420Mc (9)
wetted channel. The channel is generally “U” shaped with most
Piripaua Power Station HBRC DP982510Wb (11)
additional flow accommodated by an increase in water level
Waikaretaheke River HBRC WP982320Mf (13)
rather than an increase in river width. The dense willow habitat
that lines the river bank traps sediment and has allowed native The last five-yearly drift dive survey of trout in the Waikaretaheke
charophyte communities to establish, creating a very stable river River was undertaken in October 2008, in line with the
bank environment in the variable wetted zone. Willows play an recommendations of Kusabs (2002). The next survey is scheduled
important role in stabilising and shading the river in a landscape/ for October 2013.
geology that is highly prone to erosion and sediment runoff.
WAIKAREMOANA // 13
4.2.4 TUNA (EEL) MIGRATION PROGRAMMES
The results of ecological assessments in both summer and winter
show that the Waikaretaheke River below Piripaua Power Station In 1996 Strickland recognised the potential for improving the
supports diverse and high quality in-stream habitat; abundant upstream passage of tuna (eels) within the Waikaretaheke
periphyton growths in permanently wetted areas that did exceed catchment. From this finding, an elver catch and transfer
Ministry for the Environment (MfE) guidelines in summer but not programme began in 1996/97 with the installation of a trap
in winter; and low periphyton cover and biomass within the varial immediately downstream of Piripaua Power Station.
zone in both summer and winter. Results show that the benthic
invertebrate community within permanently wetted areas is In addition to this, a Tuna Fisheries Management Plan was
characterised by low diversity (total taxa number); moderate to developed for the Waikaremoana area following a tuna
high % Ephemeroptera, Plecoptera, and Trichoptera (EPT) (though workshop held in Tuai in January 2008, where members of the
low total EPT taxa number) in both summer and winter; low Waikaremoana community expressed concerns for their tuna
Quantitative Macro-invertebrate Community Index (QMCI) scores resource and a desire for the development of such a plan. The
in summer and moderate to high QMCI scores in winter. Overall Lake Waikaremoana Hapu Restoration Trust (LWHRT) were
the benthic invertebrate indices scores seemed to be strongly contracted to assist Genesis Energy to prepare this document with
input from NIWA. A number of hui were held to help scope the
14
influenced by periphyton cover and biomass.
plan, seek input from stakeholders and provide training for local
tuna fishers on key issues.You can also read
