Keeping you up to date with happenings on Otago’s rivers, lakes and wetlands
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Issue 6: July 2015

Welcome to the sixth edition of our Living Rivers newsletter!

As the title suggests, this publication aims to keep you, your community group, and others interested in Otago’s fresh water resources up to date with regional water issues.
Living Rivers will also inform you about how to get your own voice, and that of the community, heard in decision-making about allocation of our precious water resources. 

This issue is heavily focused on water quantity and environmental flows for Otago's rivers and streams. 

Lindis minimum flow to be notified 

Otago Regional Council (ORC) intends to notify a minimum flow for the Lindis River on Saturday 8th August 2015.   

"Plan Change 5A (Lindis: Integrated Water Management)"   
to use its official name will for the first time set a minimum flow for this seriously overallocated Central Otago river.  The Lindis routinely runs dry in summer as a result of irrigation takes causing fish kills and strandings. In future water takes for irrigation will be required to stop when a minimum flow level is reached, leaving an environmental flow to sustain the life supporting capacity and natural character of the river.

Fisheries research conducted over the last two summer seasons by Fish and Game Officer Morgan Trotter shows how damaging the existing regime is to aquatic life while wading bird surveys by Clutha Fisheries Trust indicate the lower braided reach of the river has value as a habitat for two rare native birds - black fronted tern and pied stilt.

The mean annual low flow (or MALF) in the Lindis is 1860 litres/second (l/s).  MALFs are a measure of natural summer low flows and provide a benchmark for the adequacy of minimum flows.   For the Lindis there was early discussion of a minimum flow of only 450 l/s but that sort of flow would leave areas of riverbed dry and still result in annual fish mortalities.  ORC revised their thinking upwards to 750 l/s in a presentation to a public meeting in Tarras in April 2015.  Fish and Game expects that 750 l/s will provide a connecting flow to the Clutha River but remains concerned about high water temperatures, growth of aquatic weeds and the river's complex hydrology which causes flow reductions in the lower river through losses to groundwater.   A minimum flow of 1000 l/s is considered a safer option for the aquatic environment

The public notification of the Lindis minimum flow will mark the end of an extensive round of community consultation and begin the formal plan change process .   So if you want to see a healthy flowing river all through summer you need to make a submission. Don't miss out on having your say.   

Submissions will close with ORC on Friday 4th September 2015 so note that date in your diary and don't leave your response until the last minute.
Dry Lindis River in high summer below State Highway 8 bridge.     With an adequate minimum flow this sight could be a thing of the past.

Feasibility studies completed on Manuherikia irrigation storage

The Manuherikia Catchment Water Strategy Group's (MCWSG) feasibility studies on options for increased water storage within the Manuherikia catchment are all but complete with draft ecological and summary reports approved at its last meeting on 2nd July 2015   Options for increased water storage have focused on raising the height of Falls Dam by up to 27 metres; constructing a dam on the upper Ida Burn; and looking into storage options on Hopes Creek in the Manor Burn catchment.   The Falls Dam option is the most  advanced.

Otago Fish and Game Council has been part of the group from its establishment because of the potential environmental gains to be made for the mainstem river below Falls Dam.  The Manuherikia River supports a regionally important trout fishery and trout are recognised in the Regional Plan:Water as having a significant presence within the river system. However the lower river has depleted flows in a number of reaches, notably downstream of Galloway ald some tributaries dry up, all due to historic over allocation of water by way of mining privileges or deemed permits.

Extra water storage along with the setting of residual flows on individual consents within the catchment as mining privileges are phased out could see river flows restored, fishery productivity improved and amenity values enhanced.

Raising Falls Dam does pose significant risks to indigenous flora and fauna upstream of the existing dam footprint depending on the height of the dam proposed.   Some trout spawning grounds will be flooded by a new dam along with river habitat immediately upstream but these impacts don't compare with the effects on indigenous biodiversity.  

Key targets for Fish and Game are:
  • Improved flows in the mainstem river - While the need for improved river flows below Galloway is generally accepted the existing Water Plan minimum flow at Ophir (820 litres/second) is misleading as an environmental benchmark. Although it came out of Environment Court proceedings in 2002, Fish and Game considers it to be inadequate for maintenance of a healthy river ecosystem.    820 l/s is only 26% of the naturalised MALF at Ophir (3,200 litres/second) but unlike the river at Galloway the transportation of irrigation water masks the effect of that flow level because the river is rarely below 1,500 l/s.  Fish habitat modelling also points to a higher flow requirement.
  • Adequate residual flows on existing water takes - The setting of adequate residual flows on all RMA consents replacing mining privileges within the catchment can be expected to have significant benefits for downstream flows and reduce reliance on reservoir water for river flow restoration.  
  • Improved water quality with increased irrigation - The Water Plan Schedule 15 thresholds and limits were set on the basis that water availability in the Manuherikia catchment was a limiting factor on the overall nutrient loadings especially nitrogen (N). The threshold for leaching under the ORC's permitted activity rule is 30kgN/ha/year. However, with more water available, the overall leaching rate could increase to 30kgN/ha/year over a command area three times larger than that occurring at present.  A more stringent leaching threshold, perhaps 15 kgN/ha/year, which farm system modelling has shown is possible to achieve, may to be required to ensure that the catchment does not exceed its Schedule 15 receiving water limit of 0.075 mg/l .
  • Public Access at Falls Dam - Alternative public access will be required to and along the Falls Dam reservoir shoreline if the dam height is raised.  Secure tenure for the angling huts in an equivalent shoreline location is also needed.
Although the MCWSG is taking a catchment wide approach in its consideration of options for increased water storage there may be a need for concurrent changes to the ORC's Water Plan to complement drafting of consents, supply agreements and farm plans for any new scheme that eventuates.
The Manuherikia River at Galloway suffers from very low flows in high summer limiting recreational amenity values 
Estuary knowledge gap stalls Waikouaiti River Minimum Flow setting 

A minimum flow for the Waikouaiti River has been put on hold pending further technical studies on estuary health which is expected this coming summer. 

At a meeting in Waikouaiti in April 2014 ORC sought community feedback on a minimum flow of 220 litres/second.  The mean annual low flow (MALF)  is 258 l/s so the suggested flow is 85% of MALF. However  the complex interplay between freshwater inflow and the troubled Waikouaiti Estuary deserves further investigation.

Public meeting on water yield in Taieri catchment well attended

A recent article on the Taieri catchment in the Otago Daily Times co-written by Otago Fish and Game Council environmental officer Peter Wilson, Sir Alan Mark and Robert Hofstede ( led to a public meeting in Middlemarch to discuss the underlying concepts including the beneficial effects of healthy tussock grasslands on catchment water yields. The meeting, chaired by DCC Councillor Kate Wilson, was well attended by up to 50 people representing farming, community, environment, and scientific interests.

The meeting was in agreement on the need to provide a more formal arrangement to facilitate work between irrigators, fisheries managers and the community on catchment water issues.  Watch that space.
Pomahaka minimum flow provisions now operational
On 1 June 2015, the new flow regime for the Pomahaka and Waipahi Rivers became operational. This sets a summer minimum flow of 3,600 litres/second at Burkes Ford, a winter minimum of 7000 litres/second , and an overall primary allocation limit of 1000 litres/second.   Despite the fact that the catchment is already slightly overallocated – with around 1400 l/s of water consented – these flow numbers represent a good outcome for the ecosystem and the fishery.

It is pleasing that the new regime was so well supported by the local and regional communities in the approval process and was not challenged in the Environment Court.  At 84% of the Pomahakas mean annual low flow of 4300 l/s for the new minimum flow is a respectable figure befitting a highly regarded river fishery.
Strong support for higher minimum flow in the Waiwera River
South Otago’s Waiwera River is close to having a minimum flow set to protect aquatic life following a hearing in April. It's a small river with a valued brown trout fishery and also provides habitat for longfin eels and non migratory galaxiids.   The ORC  recommended a minimum flow of 260 litres per second for the river, which has a mean annual low flow of around 310 l/s. This is 83% of MALF.  However, strong, but not universal, community support to set a higher minimum flow may result in the hearing panel considering a higher figure. The hearing panel's decision is expected soon. Fish and Game is supportive of a higher flow than 260 lps for the river, and also has pressed for a higher supplementary minimum flow. 
Lake Dunstan Lagarosiphon issue needs consideration
Public concern about lagarosiphon in Lake Dunstan has surfaced again in the media and Land Information New Zealand, the lead agency responsible for lake bed management, plan a meeting of agencies involved.   The aquatic weed is prevalant throughout the lake and can impact on recreational and aesthetic values in some locations.  However the productivity of the lake's high value trout fishery is based on largarosiphon beds even though the plant is a regarded as a nuisance species in other locations .

Otago University research has shown it is a vital component of the lake ecosystem that provides a substrate for the invertebrates on which fish feed and cover for small fish such as bullies and juvenile trout.  Largarosiphon enhances wildlife habitat values on the lake as well.  The aquatic weed was present in the Upper Clutha prior to lake-fill following the completion of the Clyde Dam and was predicted to grow strongly and colonize the lake.

Otago Fish and Game supports weed control adjacent to boat ramps, in ski lakes and in areas of high public use to retain aesthetic and recreational values but considers it should not be controlled elsewhere in the lake.   Mechanical control of largarosiphon is considered kinder on the environment than the use of herbicides.
Wonder weed or invasive pest?

Coming up...

Upcoming water issues where you could get involved are as follows:. Read some of the background information, think about attending a community meeting and/or writing a submission if invited. Its your opportunity to be heard.

Regional Policy Statement
The Regional Policy Statement (the RPS), the 'plan of plan' for Otago, sets the priorities for other important documents that affect our rivers, like the Regional Plan for Water and district council plans. The RPS is up for review, with submissions closing with ORC on Friday July 24. Fish and Game’s overall impression on the RPS is positive, as the document continues to provide strong direction for the protection of Otago’s freshwater resources. However, there will inevitably be tweaks required.

Have a look at the draft HERE ...

Plan Change 5A (Lindis: Integrated Water Management)
Otago Regional Council (ORC) intends to notify a minimum flow for the Lindis River on 
Saturday 8th August 2015. The notification will be in the Otago Daily Times and on the ORC website  ORC advise submissions will close on Friday 4th September 2015 so note that date in your diary and don't leave your response until the last minute.


Feedback Welcome!

Thanks for reading Living Rivers. We welcome your feedback on this newsletter. If you have any suggestions for content or improvements then please contact the editor here
Copyright © 2015 Otago Fish & Game Council, All rights reserved.

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