Upper Motueka – Hydrology Surface/Groundwater Monday 15th February 6.30 PM Shedwood Hall, Tapawera

Joseph Thomas Senior Resource Scientist – Water Tasman District Council

“Making Tasman Great”

1 Upper Motueka - Catchments

Re: Area above Woodstock – includes Dovedale Baton Stanley Brook Wangapeka Glen Rae Tadmor Tapawera Motupiko & Sherry

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2 “Making Tasman Great”

 We have a number of sites with flow meters that measure river flow over 24 hours  They can be found on the LAWA website they can be found on the LAWA website  Eg https://www.lawa.org.nz/explore-data/tasman-region/water-quantity/monitoring- sites/motueka-at-woodmans-bend/  River flow information is used by lots of different people including fisherman and kayakers in the Buller  We have flow records write back to the 1950's and other started in the 1980s so we have a really good historical database  Flowmeters can be used both for flood warnings but also for assessing low water flows

3 4 Water Resources Investigation Work

• Some work for the Water Conservation Order in the 90’s • Significant work from 2001 onwards as part of the ICM project • Ongoing summer river flow measurements – numerous sites • Groundwater level sites/surface flow sites – maintained and correlative sites for surface water (involves temporary flow sites) • Involved Cawthron/Landcare/GNS/TDC Hydrology – surface and groundwater/ Modelling/Allocation Ecology Landuse/Landcover Community & Iwi • Numerous Reports completed to 2013 • TRMP Plan work Monitoring in Upper Motueka – since 2015/2016 • Recent Review Work Cawthron and Landcare completed in November 2020 • Ongoing work and recommended above to 2024.

 In the past lots of money has been spent on studying water and water flows. This was done before the water conservation order. The water conservation order hearing was held and the order was signed in 2001. Fish and Game were the applicant for the water conservation order.  From the early 2000s an integrated catchment research project was commenced for the Motueka river. This involved many water flow and water quality measurements conducted by Cawthron, Landcare Research and Tasman District Council. A cultural health index was also used on the river. https://icm.landcareresearch.co.nz/

5 Pictures of the Upper Motueka Catchment

Upper Motupiko valley Lower Motueka River valley

Lower Motueka River valley Lower Motueka River valley

Motueka River lower valley

6 Hydrogeology in the Upper Motueka catchment

• A shallow unconfined alluvial aquifer located on Quaternary river terrace formations and modern river deposits – highly connected to the rivers. River and rainfall recharge dominant, hillslope recharge less. River and groundwater have short residence time • The river terraces are composed of five different Quaternary gravel formations: (1) Moutere Gravel; (2)Manuka Gravel; (3) Tophouse Gravel; (4) Speargrass Gravel; and (5) modern river Gravel formations. • The Quaternary gravels are underlain by the Moutere Gravel Formation throughout the whole study area. No appreciable groundwater has been found in the Moutere Gravel here. • The Moutere Gravel is widespread throughout the catchment and forms the hill country between the valleys of the Motueka, Motupiko and Tadmor rivers

Tophouse and Speargrass formation terraces Quaternary river terrace formations Moutere Gravel cliff faces on the Motupiko River between Tapawera and Kohatu

Motueka Aquifer  This is a shallow aquifer.  It is open to the atmosphere and is not sealed.  It is highly connected to the river.  It is largely charged by rainfall and river flow.  Not much of the water comes from the hills.  Itt is very young water only months to a year old.  Waikourupupu Spring which is approximately 10 years old.  The Motueka catchment is made up of five different River terraces.  It is the only the youngest terrace close to the river that has water.  All the hills and higher terraces have no water aquifers.  This is indirect contrast in Moutere catchment which has deep groundwater.  The Motueka aquifer is directly taking water from the river. 7  The gravels containing the water are only 10 metres.

7 Groundwater potential for each geological formation (Stewart et al., 2003)

When you get to the Glen Rae the water rises because it is pushed up by hard granite rock Green is the acquifer where the water is found

8 Cross section – Geology

Tapawera Kohatu

500 LEGEND

Modern gravels and 7 1 6

400 recent fan deposits 4 Bore (TDC bore number) LEGEND Speargrass Formation

Modern gravels and 7 Groundwater level in bore 1 recent fan deposits 6 4 Tophouse Formation Bore (TDC bore number) Inferred groundwater table Speargrass Formation 400 Groundwater level in bore Manuka Formation Tophouse Formation Inferred groundwater table l l e

e Moutere Gravel Formation

v Manuka Formation

v 300 e l e l

a a

e Moutere Gravel e s s

e e v v o o b b a a

s 300 s e e r r t t e e Motueka River M M 200 Tadmor River 8 7 1 1 4820 6 6

4 Motupiko River Motueka River 4 4615

200 4616

100

160 0 1 2 3 4 5 Kilometres 0 1 2 3 A A' B Kilometres B'

9 Upper Motueka Water Management

Councils Updated water provisions (TRMP)came into effect July 2017

Motueka River also subject to Water Conservation Order (WCO) and also Plan Triggers for this based on Woodstock and the updated zone triggers from 2017

“Making Tasman Great”

In 2017 the council updated their plan and introduced triggers for restricting water based on what was happening in Woodstock. They also introduced other monitoring sites at Wangapeka in the Baton. Some of these other subcatchments behave a bit differently than the main Motueka River.

10 Allocation Limits for Freshwater Takes

UpperMotuekaZones Allocationlimitl/s

Baton 54

StanleyBrook 1.05

Dovedale - Groundwater (to 8 metres) 13.2 - Surface water 26.8

MiddleMotuekaZone 550

Wangapeka 265

Motupiko 85

RainyZone 25

Tadmor(totalaugmentedflow) 56

Tapawera 314

Glen Rae 300

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11 Triggers for Rationing and Minimum Flows

Trigger for First Rationing Trigger for Minimum Flow Water Management Zone Location Step Consultation (l/sec) (l/sec) (l/sec)

Upper Motueka Zone

Motupiko, Rainy, Tapawera, Woodstock Subject to WCO 7000 7500 Glen Rae, Baton, Wangapeka

Tadmor River Mudstone Weir Subject to WCO 128 Downstream of Hope River 20 None diversion weir Rainy Christies 203 250 400

Motupiko Christies 250 400

Motueka River, above Tapawera, Glen Rae the Wangapeka 1400 Confluence

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12 Water user committees will be consulted when rationing triggers are reached.

The minimum flows for Middle and Upper Motueka zones will be consistent with the Water Conservation Order for the Motueka River.

The Council will implement rationing to comply with the Motueka WCO flow extraction limits of 12% above Woodstock, and 6% for Wangapeka above Walter Peak. It will also implement rationing to protect river flows in contributing tributaries.

Council will use correlation and actual flow measurements to manage Tapawera and Glen Rae Zones

In the Rainy and Motupiko zones, Step 2 rationing will commence at 200 litres per second and Step 3 at 180 litres per second. Used S329 for cease take at ~150 l/s

Specific restrictions and cease take in Consent for Rainy – 203 l/s

If water flows or levels decrease below the minimum flows or levels specified in this schedule and the provisions of the rationing steps given in the TRMP are exceeded, the Council may issue water shortage

directions (S329) in accordance with its policies“Making Tasman Great”

Land owners are subjected to reductions in take or stop takes, based on water flow triggers for rationing water. The plan specifies the proportion of water that can be taken. All water extractions are metered. When it is dry and lots of water has been taken from the river, river flows can drop quite quickly.

13 Water Resource Considerations for Summer Restrictions in Upper Motueka

River Flow and Aquifer Levels and rate of decline and when Rainfall Water Usage Temperature Wind Evapotranspiration Timing – of peaking of different use

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14 Catchment Hydrology Information

• Rainfall • River Flows • Groundwater

The last 3 years of being dry relative to the average. A flow recorder cost 20k so to reduce costs we have developed predictors between different sites along the river. This allows us to optimise the measurements of flow at the key points when assessing flow we use the 7-day average. We have started to collect data from bores so that we can keep a better eye on the aquifer. All the data is stored on the LAWA website. We are also recording temperature at 7 sites along the River.

15 16 17 18 19 20 • We have developed predictors between different sites along the river. • This allows us to optimise the measurements of flow at the key points. • When assessing flow we use the 7-day average. • We are getting reasonable prediction of river flows. • R2 of 0.877 means that 87% of the variation of flow of water at Tapawera is explaind by flow at Wangapeka

21 22 The river has more flow than it did last year at the same time of year

23 24 25 We are also measuring groundwater over recent years

26 27 Current Work in the Upper Motueka

• Low flow and temperature measurements in river between Kohatu and Wangapeka Confluence (last 4 summers – flow dependent) as well as Motupiko last summer • Water Take Monitoring of all consents (metered) • Water quality run along river from Kohatu to u/s Wangapeka confluence • Dissolved Oxygen – now added at Kohatu and U/s of Wangapeka • Cawthron/Landcare – review of monitoring – November 2020

“Making Tasman Great”

• We are recording temperature at 7 sites along the River. • The River gets very warm. Some people think that it's the irrigation making the water warm. But it's much more likely that it's the exposure of the River to the sun. There is limited cover on the riverbank. • There is not an easy solution because the River is very wide. • We are monitoring water take from the River, flows and we have two permanent oxygen sensors in the River that record oxygen levels over 24 hour periods over summer. • Cawthron and Landcare Research did a report reviewing our data collection and made some recommendations which we are implementing. 28 Cawthron/Landcare Recommendations

• Continue all current monitoring and; • Trial fixed cameras to record river drying at lower Motupiko and Tadmor • Update river/aquifer model • Annual monitoring of water clarity, nutrients, faecal indicator bacteria, macroinvertebrate community and periphyton cover at Motueka River u/s of Motupiko confluence and Motueka u/s Wangapeka confluence • Snapshot summer surface water quality at multiple sites in conjunction with planned synoptic groundwater quality survey • Review data and plan 24/25

• One of the recommendations was to include cameras and data loggers along rivers that run dry so we can tell when they run dry. • Some people are concerned about the water aquifer and about all the recent hops taking all the water at the same time of the year. We are going improving our knowledge of the aquifer. We are going to review the data and then look to see if any changes are needed in the 24/25 plan .

29 Questions?

“Making Tasman Great”

How can we support as a community the water quality sampling ? The council can provide expertise and may be able to accommodate sampling but water sampling has big costs. We could potentially loan equipment eg temperature loggers or O2 measurements. But there is a very strict methodology for water quality testing on how sample is collected, stored and what labs should be used when water quality sampling. Samples often have to arrive at the lab within 24 hours.

Is there an issue with nitrates in our water? There is a rumour going around that the local testing of the Tapawera water supply showed and increase in nitrates. They had increased from 2 to 4 mg/L but are still well below the 11 mg/L.

The council is sampling other wells throughout the region. The latest few nitrate samples collected from Tapawera had fallen. So it's not a concern at the moment but needs to be watched.

Two years ago in Murchison the aquifer was tested for pesticides ($1500/sample). No pesticides or Roundup was found in the water.

If we do need to reduce water allocation how will it be done? There are a number of smaller water users that are concerned that if they don’t use all their water allocation they will loose it. So they are putting water on when they don’t really need it.

30 It is undecided at this point. With water permits we do look at the history of the water use to base the new permit. But we don’t encourage inefficient water use. Rather I suggest that if you don’t use your allocation you could lease out your water allocation on a short term lease to someone else. There are a number of options we could set target water reductions including not allocating any new water permits, we could reduce everyone intake on a percentage basis. As a current general guidelines at the moment if you use 80% of your water intake you can still renew it at 1.00%

30 What are the new things on the horizon around water quantity? Everyone will need a farm environmental plan. Irrigators will need soil moisture probes. Next time you go to get your water allocation you will need an irrigation plant.

Should we be worried about heavy metals coming out of tanilised posts? Heavy metals tend not to be very mobile. Painting the top of the poles reduces the movement of chemicals out of the posts. Marlborough studies have shown the chemicals don’t more far from the post and become bound to the soil.

Can we pose forestry limits in the catchment? TDC can only place limits of forestry in areas with <900 mm of rain eg Moutere, Wai Iti. Trees both absorb and release water. There are more stringent forestry rules for the Separation Granite soils with greater setbacks. And after harvest some areas can’t be replanted.

What risks do Climate change pose to the catchment? There will be habitat issues in the river associated with higher water temperatures. Council has had two reports done by NIWA that can be found on our website. In summer hotter summers, bigger storm events, more flooding in winter.

How can we help cool the water? We can look at adding groynes with deep pools We could look at groynes which create refuges for fish and macro invertebrates in the have exchange some of the colder aquifer water with the water of the river River. Riparian plantings along the River and tributaries will help shade the River Tapawera Awa Ora has started on those plantings. There is also an IWI project working on the river.

In the Sherry River after 13 years of planting it is very bare under the riparian plantings and this is not preventing overflow. Should we be doing this?

31 Scion is recommending sparse plantings to retain some pasture. Alternatively a pasture area could be retained on the paddock side of the riparian planting. Flaxes and sedges can help capture flow.

What were the findings from Donald Creek? . This paired catchment study conducted by Andrew Fenemore had a lot of good information. While Andrew Fenemore has retired he is keen to retain links with the Motueka catchment and sent his apologies for missing this meeting. Cawthron is collecting allot of information on sediment in the Motueka Catchment.

31 Upper Motueka Current Status and Outlook

• River Flows - about average for this time • Aquifers – about average for this time • Eastern Part of Tasman Drier – Motupiko/Wai-it/Dovedale/Waimea/Moutere to Motueka Plains along the coast • Many dams not full e.g. Moutere dams a bit of pumping from groundwater to storage • Wai-iti Dam (Wai-iti Zone) ~ 85 % full • Short term outlook (10 days) – only minor rain • Current Rainfall in Upper Motueka behind averages except Wangapeka • Early in the season for peak demand ~ Jan to Mid March • Continue close monitoring of all water use including hops • Note; Small Nature of Catchments and Aquifers – things can turn quickly – when dry/windy and water usage increases

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32 Seasonal climate outlook Dec – February 2021 – NIWA Currently a “La Nina” pattern is predicted for NZ – wet in the north, dry in the south and warm

Probabilities are assigned in three categories: above average, near average, and below average.

Temperatures are very likely to be above average (70% chance). Rainfall totals are about equally likely to be near normal (40% chance) or above normal (35% chance). Soil moisture levels and river flows are most likely to be near normal (40% chance).

Temperature Rainfall Soil moisture River flows

Above average 70 35 30 30

Near average 20 40 40 40

Below average 10 25 30 30

33