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2 Background to the Application

2.1 The Application

  1. In May 2005 the New Zealand Fish and Game Council and Southland Fish and Game Council applied to the Minister for a water conservation order for the Oreti River under Section 216(2) of the Act.
  2. The application was supported by further information that described the catchment and its values, and outlined the detail of the order sought. In essence Fish and Game sought protection of flows and water quality in the main stem of the river and its tributaries from Rocky Point, which is near Mossburn, upstream. We have called this the upper Oreti catchment. The protection sought would also restrict the taking of hydraulically connected shallow groundwater in the upper catchment. The applicant also sought a prohibition of damming of the full flow of the river downstream of Mossburn (which we have called the lower Oreti catchment), and a full prohibition of damming the mainstem upstream of Mossburn. No water quality or quantity provisions were sought in the lower catchment.
  3. In August 2005 the Minister sought additional information to better define what was meant in the application by “hydraulically connected groundwater”. Solicitors for the applicant forwarded a definition from a policy in Proposed Variation 2 (Groundwater) to the Proposed Freshwater Plan. We need not detail that here as we return to this matter later .
  4. We were appointed by the Minister by letter dated 6 September 2006.

2.2 Notification

  1. The application was notified pursuant to s204 of the Act on 30 September 2006. This included notification in each of the major metropolitan dailies and the local media. Copies of the application could be viewed at offices of the Ministry, at the offices of local authorities in Invercargill, Gore or Queenstown, and at libraries at Te Anau, Lumsden and Winton.
  2. The Ministry received 77 submissions by the time they closed on 15 November 2006. Of those submissions, 63 supported the application, 13 opposed it and one was neutral. There was one late submission which we accepted. A full list of submitters is provided in Annex A. One submitter (the Royal Forest and Bird Protection Society of New Zealand, Southland Branch) originally did not ask to be heard but later requested to be so. We granted this request.

2.3 Description of the Catchment and its Management

2.3.1 The Setting

  1. The Oreti River rises between the Thompson and Eyre mountains to the south of Lake Wakatipu. It is bounded to the north by the Von River, a tributary of Lake Wakatipu, to the east by the Mataura River catchment, and to the west by the Mararoa River catchment. In its headwaters the Oreti runs approximately southwest, before turning south near the junction of the Windley River and then running southeast or south across the undulating Southland Plains to enter the coast west of Invercargill. The gradient of the river is steepest upstream of Lumsden.
  2. The Oreti River, which is approximately 200 km long, has the third-largest mean annual flow of rivers in Southland. In the upper catchment the river is predominantly single thread, but it becomes a little braided downstream of about Rocky Point, with flow generally in two or three channels. The river becomes single thread downstream of about Winton to the coast.
  3. The headwaters of the Oreti River lie in highly dissected mountains up to about 2000 metres high. From here the upper river flows across a wide, U-shaped outwash plain valley formed by one of the tongues of the Wakatipu Glacier. The upper valley is characterised by tussock grasslands on the river flats, through which many small, spring-fed seepages run. The channel is dominated by quite long pools or runs up to about two metres deep separated by short riffles. The bed of the river is characterised by gravels and cobbles which would move freely during floods. Importantly, the river is not at all embedded.1 There are a few locations, such as at Lincoln Hill, where the river flows between rock buttresses, but the valley is generally very open and, we were assured, often windswept.
  4. The largest tributary, the Windley River, rises in the Eyre Mountains and enters from the east or true left. The other main tributaries in the headwaters are the Ashton River, another high-country sourced river that enters from the east, and meandering Weydon Burn, which enters from the west near State Highway 94.
  5. The headwaters of the river are generally in the tenure of the Department of Conservation (DOC), with the Eyre Mountains having been gazetted in 2005 as the Eyre Mountain Ecological Reserve. The river then enters public land in the tenure of Mount Nicholas Station, and the riverbed is used for extensive summer grazing of cattle in particular. Further downstream the upper catchment is largely in the tenure of Landcorp on the true right, and other private landowners (including two submitters: Andrew Morris and Peter Lawson) on the true left downstream of the Windley River. In this reach much of the river is fenced off from stock, but stock access is certainly possible higher up on Mount Nicholas. Land use is generally extensive, with some production forestry stands also present.
  6. As the river crosses the Southland Plains, land use changes to more intensive sheep, dairying and cropping.
  7. Access to the upper catchment is via a well formed gravel road that leads from State Highway 94 along the west bank of the river to the upper reaches of the catchment on Mount Nicholas station. There are a number of points where anglers can park and walk fairly easily to the river. There are no high bluffs that impede access to or along the river, and during normal flows the river can readily be waded.

2.3.2 Catchment Hydrology

  1. Hydrological information for the catchment was summarised by Ms Jan Riddell, appearing as a witness for the applicant. She had obtained the relevant records from the regional council.
  2. There are three main hydrological recording stations on the river. These are at Three Kings in the upper catchment about 30 kilometres upstream of Mossburn, Lumsden (close to the middle of the catchment) and Wallacetown, near the mouth of the river. Their catchment areas are 271, 1,125 and 2,141 square kilometres respectively. The latter two sites have been operational for about 30 years and that at Three Kings for over 20 years.
  3. Mean annual flows in cubic metres per second (m3/s) are 8.65, 29 and 41.3 m3/s at Three Kings, Lumsden and Wallacetown respectively. Seven-day mean annual low flows (MALF) at the three sites are 2.5, 5.7 and 8.3 m3/s respectively.
  4. The Three Kings site shows a somewhat unusual hydrological feature in that the MALF is almost 30% of the mean flow. This reflects the extent to which low flows are buffered by shallow groundwater inflows in the upper catchment. According to Mr Rekker, a witness for the applicant, groundwater makes up about 60% of the base flow at Three Kings. As a result, flow variations, particularly at low flows, are less marked in the upper catchment than at sites further downriver.
  5. Mean annual rainfall at Three Kings is 1,196 mm per year. Rainfall is reasonably consistent and reliable on both a monthly and annual basis, with annual rainfalls varying from about 800 mm to 1,500 mm. Spring is typically a little wetter than other periods, and winter a little drier. Rainfall is generally quite reliable. In the 20 years of record at least 0.5 mm of rain has fallen on average on 166 days per year. In most years of record there are between six and nine periods of more than eight days with rain of less than 1 mm. Periods of 20 or more days with less than 1 mm of rain have occurred once in May, June, September and December and twice in March and July in the 20 years of record.
  6. Mean monthly flows at Three Kings vary from 6.25 m3/s in February to 12.87 m3/s in October. The lowest flow mean daily flow recorded of 1.39 m3/s occurred in March 1990, and the highest flow recorded was estimated to be 171 m3/s. The upper river is subject to reasonably frequent and reliable freshes and floods. The longest periods of sustained low flows occurred in February and March of 1990 (34 days), and 1999 (31 days).
  7. Under sustained low-flow conditions water is apparently lost from the Oreti River downstream of Lumsden. Such losses are inferred to be to shallow groundwater.

2.3.3 Water Quality and the Invertebrate Fauna

  1. In the upper catchment water quality is high, and water clarity can be exceptionally high. A study compiled by NIWA scientists of 190 observations in 96 rivers at base flow showed the upper Oreti to have water clarity in the top 20% of those rivers. Other parameters are also indicative of high water quality. For instance, recorded levels of dissolved oxygen are always high, whereas levels of nutrients and ammonia are always low. There has been no recorded decline in water quality in the upper river.
  2. In Māori conceptualisations, water quality is vital to sustaining a healthy and vibrant mauri – the life principle.
  3. In the headwater reaches of the river the invertebrate community is dominated by species such as mayflies, stoneflies and caddisflies, which are indicative of high water quality. These insects form a major part of trout diets. The invertebrate community remains indicative of high water quality as far downstream as Lumsden, but in the lower reaches of the river is indicative of possible mild pollution.
  4. Environment Southland has collected water temperature data in the upper river continuously at Three Kings since 1998. The highest spot temperature recorded was 25 degrees centigrade, but the highest daily average temperature was only 17.5 degrees. The average water temperature seldom dropped below 4 degrees for more than several days in winter.
  5. The invasive alga Didymosphenia geminata (“didymo”) is present in the river. This is the first application for a water conservation order heard at a time that didymo was present in a river. We discuss this in detail later in this report.

2.3.4 The Regional Planning Context

  1. Management of the water resources of the Oreti catchment are the responsibility of the Southland Regional Council, which has branded itself as “Environment Southland”. The regional council is responsible for managing all of the surface water and groundwater resources in the region, along with discharges to water and to land where they may enter water. At our request Ms Millar, the council’s Senior Resource Planner primarily responsible for water resource planning, gave us a very good outline of the council’s management regime in the catchment, which we summarise here.
  2. The principal document that sets the framework for the management of the water resources of the Oreti River is the Proposed Regional Fresh Water Plan (“the Water Plan”). Other plans of some relevance, in so far as they place controls on discharges to land and water in the catchment, are the Regional Solid Waste Management Plan and the Regional Effluent Land Application Plan.
  3. The Water Plan was originally notified in October 2000. Since that time, however, both the demand for water and the understanding of the water resources of the region have increased substantially. As a result of this the council has notified five variations to the plan between 2003 and 2006. It has now heard submissions, and made decisions on all these variations. The decisions relating respectively to groundwater, water quantity and water quality were released on 31 March 2007, and the remaining variations were released on 14 July 2007.
  4. Appeals on the March decisions closed on 16 May 2007. One of the appeals was from Fish and Game and related specifically to the Oreti catchment. We discuss this later in this report. We also discuss later the provisions of the plan as they relate to the water conservation order application.
  5. The water planning process, and the associated extensive consultation that had been undertaken by Environment Southland, was widely commended by many participants to the hearing, be they primarily interested in conservation or in development. We consider that this is a credit to the council and its staff.

2.3.5 Use of the Catchment

  1. Ms Riddell said that according to regional council databases, consents exist for 94 land use consents, 266 discharge permits, 109 groundwater takes and 16 surface water takes in the catchment upstream of Wallacetown. Although permits have been granted to dam some small tributary streams, no current permit authorises damming of the main stem of the river at any point.
  2. Only eight of those permits apply to the river upstream of Mossburn. Three are land use consents held by Environment Southland for river control purposes. Another consent held by the regional council is for aerial spraying of herbicides to control plant pests. The other consents are either for river control or bridge construction/maintenance purposes, and one consent authorises the taking of up to 100,000 cubic metres of gravel from the river.
  3. There are no consented point source discharges to the upper catchment, nor are there any consents to dam or take water (including hydraulically connected groundwater) upstream of Rocky Point. The only present consent in the upper catchment upstream of the confluence of the Weydon Burn is held by Environment Southland who, in exercising their powers under the Soil Conservation and Rivers Control Act 1941, undertake occasional river control works to prevent the river from eroding towards farmland on the east downstream of the Ashton River confluence.
  4. As indicated by the consents database, the river downstream of Mossburn has many more uses. It supplies water treated to a standard suitable for domestic supplies in Invercargill, and through (at least partly) hydraulically connected groundwater, to communities such as Mossburn and Lumsden. Gravel is taken from the middle reaches of the river, and there is some use of surface water and hydraulically connected groundwater for seasonal irrigation. Water quality declines downstream, primarily due to the effects of non-point source runoff from intensively farmed land.

2.3.6 Management of the Brown Trout Fishery

  1. The brown trout fishery of the Oreti River is managed, in what we consider to be a very competent fashion, by Southland Fish and Game, whose region closely coincides with that of Environment Southland. Native fisheries are the responsibility of the Department of Conservation. The trout fishing season on the upper Oreti is from October to April inclusive.
  2. Because of concerns about angling pressure in the upper river, Fish and Game introduced a mandatory “catch-and-release” policy in a reach of approximately 15 km downstream of the Mt Nicholas Bridge in the early 1990’s. This reach is also a “walk only” zone. The success of this policy may be reflected in average numbers of large trout per kilometre in the upper river increasing from 6-8 about 15 years ago to close to 30 per kilometre today.
  3. Anyone with a fishing licence can presently fish this reach of the river. Two other nearby headwater fisheries, the Greenstone and the Caples in Fiordland National Park, have ballot systems operating, but there is no proposal at present to introduce a similar system on the upper Oreti.

1 This is important in so far as the unstable bed limits the opportunity for extensive growths of Didymo. We discuss this matter at some length later.

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