Canterbury Strategic Water Study CSWS A Summary

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Canterbury Strategic Water Study (CSWS) - A
Summary
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Evaluating storage options . . .

• Group of 15 - 28 including individuals from Fish
  Game, local farmers, Community Development,
  Ngai Tahu, a Resource Management consultant,
  farmers from across Canterbury,
  environmentalists, Irrigation New Zealand and
  Water Rights Trust, Forest Bird, and others
  with an interest in water.
• People present in personal capacity, not as
  representatives
• Group identifies additional options to those from
  Stage 2.
• Evaluate each option against 22 topics covering
  social, economic, cultural environmental
  impacts on 6-point scale.
• Evaluation in three bites
• Hurunui
• South Canterbury
• Rangitata River Ashley River

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• Based on Aqualinc identifying hydrologically-feasi
  ble storages that increase irrigable area and
  improve reliability
• Only considered options based on major reservoirs
  (gt50,000,000m3) (almost all in-channel)
• Many options considered,
• rejected, by Aqualinc

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• All options integrate run-of-river takes with
  storage
• Run-of-river water used to meet irrigation demand
  whenever possible
• Releases from storage used to meet run-of-river
  shortfall (particularly in late summer dry
  seasons).

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Overall . . .

• All options have positive and negatives.
• For some Group participants, all options are
  acceptable
• For some, all options are unacceptable
• Overarching concerns about
• irrigation leading to
• land use intensification
• which means adverse
• impacts on water quality

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CSWS Evaluation groups

• Farmers irrigators in majority
• Range of other interests (environment,
  conservation, angling, kayaking, community
  development . .)
• Few women, Maori, or people from small towns
• Limited number of people had on-the-ground
  knowledge of proposed sites

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CSWS Stage 3 was not

• A process with statutory standing
• A technical evaluation of water quality or other
  environmental impacts
• Based on site visits

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Evaluation of Hurunui options

• Range of options based on South Branch dam, Lake
  Sumner and a dam on a mid-Hurunui tributary (e.g.
  Mandamus).
• Groups thinking changed through the process with
  the option of managing Lake Sumner within
  historical range becoming more attractive as
  concerns increased about a high dam on South
  Branch with loss of salmon fishery and other
  adverse impacts
• A combination of managing Lake Sumner with some
  other back-up storage (but not South Branch
  dam) may allow much of the land to be irrigated
• Aqualinc modeling results need to be revised
  given proposed Hurunui River Regime Plan

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Comments from interest group discussions on
Hurunui options

• Big dams not favoured, particularly on main
  tributaries. On-farm storage offered as an
  alternative.
• Irrigation seen as intensive dairying and leading
  to N P pollution bad bugs. Skeptical (at
  best) that best practice would solve issue.
• How can this be a strategic study if one of the
  options NO DAMS is not being considered? Some
  strong opposition to dams on rivers, more
  irrigation dairying.
• Irrigation seen as only benefiting farmers at a
  cost to the environment with society (not the
  farmers) bearing the consequences of land-use
  practices.
• Hurunui District mayor councilors recognise the
  need to have a strategy for water and development
  as part of their long term plan.
• National Conservation order application for
  Hurunui River lodged.

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How the group felt about the options . .
South Branch (current rules)
L. Sumner (with natural lake variation)
Raised Sumner
South Branch (Mosley rules)
L. Sumner (without var.)
L. Sumner Mandamus (with natural var.)
South Branch L. Sumner
L. Sumner Mandamus (without var.)
L. Sumner South Branch
Evaluation scale
Strongly positive
Strongly negative
Neutral
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South Canterbury options

• Using only water from within area
• Raised Opuha dam
• Opuha dam Opihi dam (near Fairlie)
• Pareora dam
• With Tekapo water
• Opuha Opihi dam (two operating ranges)
• Opuha Tengawai dam
• Opuha off-channel storage
• Opuha only

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South Canterbury evaluation

• Very water-short area. Storage options
  constrained by water availability (Opuha, Opihi,
  Tengawai, Pareora)
• Opuha scheme is unlikely to be able to meet
  demand of its existing irrigators in all years.
  In very dry times, like in 1988, lake may not
  refill in winter/autumn irrigation restrictions
  of 3 months or more
• Tekapo water required but significant challenges
  
• Meridian consent
• cultural (water mixing)
• environmental
• use of water for electricity generation
• versus use for irrigation.
• Prefer option based on use of
• Tekapo water with current Opuha
• Pareora stand alone option but
• more hydrology needed

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How the group felt about the options . .
With water from Tekapo
Using local water only
Opuha Opihi 20m range
Raised Opuha
5m range
Opuha Tengawai
Opuha Opihi
Opuha off-channel storage
(Stoneleigh Rd)
Pareora
Opuha only
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Mid-central Canterbury evaluation

• Options Lees Valley, Wainiwaniwa Valley, Lake
  Coleridge water, Stour Valley
• For some of Group all options OK, for others none
  are acceptable
• Participants see storage as critical
• Some believe major storage is only
• option (economically)
• Others think smaller storages
• require more consideration
• Integrated option worth considering

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Lees Valley

• BIG is a positive a negative
• Supplies all irrigable area north of Rakaia
• Big economic benefit
• Big environmental risks
• Single solution (no CPW)
• 1 billion
• Huge dam
• Long time for initial filling
• Significant impacts on
• Waimakariri and Ashley Rivers

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Waininaniwa Valley

• Option evaluated similar to CPW except water not
  restricted to Selwyn area (could use water north
  as well)
• Evaluation echoed concerns and advantages
  expressed in media and letters to newspapers
• More immediately do-able than Lees Valley

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Lake Coleridge

• Trustpower provided limited information, on a
  confidential basis, on an option they are scoping
• Diverts water from Lake Coleridge for new power
  generation water to north south (siphon) for
  irrigation
• Non-compliance with Rakaia WCO a major hurdle
  even though
• Operates within consent conditions for Harper,
  Wilberforce and Coleridge lake levels
• Likely little impact on Rakaia flows below Gorge
• Requires other storage Coleridge storage able
  to improve short-term reliability of supply but
  not dry-year reliability

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Stour Valley

• Water diverted from South Ashburton to reservoir
  in Stour Valley
• Rakaia and Rangitata River takes
• Utilises RDR BCI infrastructure (with changes
  to get water south of Ashburton River)
• Concerns about impacts on wetlands, iconic lakes
  landscape in/near Stour valley (area
  recommended for World Heritage status)
• Adverse impacts on Ashburton River flows (though
  may be able to improve flows in lower river)

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No major storage option

• Group had an initial discussion of the impacts if
  there was no new (major) water storage in
  mid-central Canterbury
• Irrigation development would stop, probably
  contract
• Farmers increasingly struggle to meet market
  expectations (time- and product-specific)
• Rural economy decline (with flow on impact on
  rural towns Christchurch) and impact on social
  infrastructure
• Loss of opportunities to use releases from
  storage to improve river ecosystems (as done in
  Opuha)
• Reduced environmental impacts/risks (stop land
  intensification reduce new run-of-river takes)
  but extent debated

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How people felt about the options
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An integrated option

• At the last meeting of the mid-central Group, an
  integrated option was proposed to
• provide new irrigation
• improve low flows and flow variability in most
  rivers
• only require one new storage reservoir
• supply water south of Rangitata, if possible
• Aqualinc has modelled initial results

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An integrated option

• For the area from Ashley River to Rangitata
  River an option that
• provides water for significant new irrigation
• improves low flows and flow variability in most
  rivers
• only requires one new storage reservoir
• supplies water south of Rangitata, if possible

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Esk R
L Coleridge
X
X
X
X
RDR
Lees Vly
Rakaia R
Waimakariri R
X run-of river takes
Reservoirs/lakes
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Ashley Gorge
Head race schematic only
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RDR BCI
141,000ha irrigable area
Increased flows in lowland streams
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X
X
Lake filling time
X
Water quality concerns
Meeting water demand
CRUNCH issues CHALLENGES to be worked through
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Where to . ..

• Are we close?
• Could we work together to find innovative
  solutions for Canterburys future prosperity that
  use water wisely for primary production with
  environmental gains . . . .