What is Nature Calls?

Photo shows ponds with flaxes with trees and hills in background.

Nature Calls is one of the largest projects Palmerston North City Council has undertaken, and the biggest environmental and financial decision for our city.

Every time you remove a sink plug, flush a toilet, turn off a tap, your dishwasher finishes a cycle or your washing machine beeps —  that water goes to our Wastewater Treatment Plant at Tōtara Road, where it's treated before being discharged into the Manawatū River.

Managing water resources and the discharge of wastewater is the joint responsibility of Palmerston North City Council (as applicant) and Horizons Regional Council (as regulator). The mechanism that allows us to discharge our treated wastewater is the resource consent process under the Resource Management Act (RMA).

This project focuses on how we treat and discharge the wastewater we create, for the next 30 to 50 years

In Palmerston North, we do a pretty good job of managing our wastewater. We highly treat and discharge our wastewater to consistently meet conditions set in our resource consent. However we need to apply for new consents by mid-2022 as part of a process to continually review and improve our environment.

Since we got our last consent back in 2006, laws and standards have changed, along with many people's views about the environment. This means that our current treatment method isn't sufficient to meet future requirements, given our growth and higher standards.

The RMA process requires an option that appropriately avoids or mitigates adverse effects on the environment and meets the purpose and principles of the RMA (Part 2). To meet these requirements we will investigate – and show proof of – our analysis of possible options and the potential effects on the natural, social, cultural and economic environments.

In 2021, Council selected its best practicable option.

During our Long-Term Plan consultation in April/May 2024, we heard from our community that they’re concerned about the affordability of our Nature Calls project.

As a result, during Long-Term Plan deliberations, our elected members have made two key decisions about this project.

Project cost reduced

The cost of the project in our Long-Term Plan has been reduced.

We had proposed that the cost was $647M including inflation over the ten year period. This was too much for Council to borrow and would need to be borrowed through external funding. We proposed that this would have a cost of at least $1000 per property each year for the life of the consent, on top of rates. This would start once construction began.

As a result of submissions, Elected Members have reduced the budget to $480M excluding inflation.

Consent application to be paused

Elected Members have also decided to put a pause on the current consent application which is with Horizons Regional Council, to allow council staff the time to look at other options for how we could bring the cost of the project down for our community.

This could look at things like different options for discharge, staging, new technology etc. This will be brought back to Council for elected members to consider next steps.

We’ve made Horizons Regional Council aware of these decisions informally, but once our Long-Term Plan is adopted on 26 June, we will send formal notification of our request to pause the consent application. We will meet with them and determine the next steps for the project.

These decisions come as a direct result of community feedback, and demonstrates that we’re taking our community concerns about affordability seriously. It also upholds the integrity of the process we’ve followed over the past five years with our community, iwi and stakeholder groups – and reflects that we’re committed to finding a measured outcome that meets legal requirements, environmental improvements, affordability and community, iwi and stakeholder aspirations. The work we’ve already done will not be lost, but rather will be vital as we look at next steps for this project.

We will continue to work with our partners, and community on this project, and provide updates as soon as we are able to do so.

January 2024 update

In February 2024, we’ll be doing more water testing to determine the potential impacts of our treated wastewater in the future.

There are two different types of work occurring, in two different areas.

Dye testing in the Manawatū River

In late January and February, weather dependent, we will be conducting dye testing on a small portion of the river to help model how quickly the treated wastewater will disperse into the river water from our proposed new discharge point. Unfortunately, the river level has been too high for us to do this safely over the past 18 months but the dry summer we’ve had so far means the river level is now low enough for us to safely do this work.

The dye will be released at two separate locations:

  1. downstream of the Mangaone Stream, and
  2. downstream of Longburn (near proposed new discharge point).

The purpose is to see how it dilutes and mixes with the river water, which will give a good indication of how the wastewater will do the same. The dye is red in colour so that it is easily visible to eye when released into the river.

The type of dye is a common dye used around New Zealand and the world for water sampling due to its quick disintegration in the water. When the dye enters the river we use our drone to watch how the dye interacts as well as other ‘on-water’ tests. This then gets analysed as well as the samples done on-site.

This work helps confirm our modelling and determine if any changes to our proposal are needed. It is a requirement for our consent application.

If you see the dye, you don’t need to be concerned. We’ve let iwi, Horizons and some of the landowners directly next to the areas we are working know about this work occurring.

If we cannot do the work in January, we will look to do it in February instead, if the river level stays low.

Stream and drain testing west to the city also occurring

As Horizons Regional Council doesn’t currently collect surface water quality data and ecological information for four water bodies in our proposed area of interest for the land discharge, we are required to do that testing as part of our consent application. As land discharge will occur in the wider area, these streams have been identified as streams that could be impacted – so it’s important we know their current state.

The four locations of testing are Whiskey Creek at the intersect with Rangiotu Road. Bourkes Drain at the intersect with Lockwood Road, Main Drain at the intersect of Lockwood Road and Kairanga Bunnythorpe Road and Taonui Stream at the intersect of Rongotea Road.

Testing will involve at least two people visiting the site to test the water quality in different circumstances. A single water quality sample will be collected and analysed for Nitrate nitrogen; nitrite nitrogen, ammoniacal nitrogen; soluble inorganic nitrogen; total Kjeldahl nitrogen; total nitrogen, dissolved reactive phosphorus; total phosphorus; sodium; electrical conductivity and Escherichia coli. Measurements of temperature, dissolved oxygen, and pH will also be recorded.

The ecological assessment will include a habitat assessment, environmental DNA (eDNA) samples to determine fish species presence (6 per site) and a determination of the overall ecological value of water bodies at these locations.

We’re talking to the landowners around the testing site. The testing locations do not indicate land parcels we are interested in purchasing/using but rather these streams and drains have been identified by Horizons Regional Council as needing water quality assessments. We have chosen areas where they intersect with roads so that there is easy access and the work doesn’t need to disrupt any of the landowners’ work.

Palmerston North City Council will continue to provide updates here at www.naturecalls.nz


August 2023 update

In August 2023, Horizons Regional Council accepted our consent application as complete. This means Horizons, as regulator, will now begin assessing our application for how we treat and discharge wastewater in the future.

Based on other infrastructure projects of this scale, we expect this process will take some time.

We will continue to provide public updates when and where appropriate, but public updates on the process will now primarily come from Horizons.

We still have a huge amount of work ahead of us. We remain committed to working with our community, iwi and other stakeholders.

3 April 2023 update

On the afternoon of Friday 31 March 2023, Horizons Regional Council let us know our consent application had been rejected due to insufficient information.

We lodged our application in December. The next step was for Horizons, which is the consenting authority, to undertake a ‘completeness check’. This is an administrative check required under section 88 of the Resource Management Act (RMA). This occurs before the application proceeds to the next stage of review and consideration.

Section 88 of the RMA gives a consenting authority 10 working days to determine whether the application was complete. We agreed to an extension given the impact on resources during the weather events during this period, which provided Horizons with 47 working days to undertake the review.

We are still working through the detail that has been provided by Horizons Regional Council and will look to meet with them with urgency to get more information to go through the next steps and get some new timelines in place.   

While disappointing, we want to reassure our community that Palmerston North is committed to getting our consent and obtaining the best outcome for our city, our environment and our awa. 

Horizons Regional Council has released the following statement to media: 

"Horizons Regional Council has undertaken a robust and comprehensive review of the application made by Palmerston North City Council to discharge treated wastewater to water and land. We would like to commend and acknowledge PNCC for the large volume of work and scale of assessment undertaken to support their application. The initial review of any consent application received is to ensure that an application contains sufficient information to enable assessment and undertake a robust consent process. Unfortunately the application was lacking information, specifically with respect to the proposed discharge to land component of the application. As a result, Horizons has returned the application as incomplete. Horizons is committed to working with all parties moving forward, to provide advice to ensure that a complete consent application can be lodged."

21 December 2022 update

The consent application for how we’re proposing to treat and discharge our city’s wastewater/resource water over the coming decades has now been submitted to Horizons Regional Council.

After four years of significant technical work and public engagement, our application outlines how we’re proposing to treat the city’s wastewater/resource water to the highest standard currently available in New Zealand.

Mayor Grant Smith says lodging our application is a key milestone for the project.

He says our consent application proposes that wastewater/resource water treated to one of the highest treated wastewater processes in New Zealand for municipal wastewater would be discharged to a combination of river and land.

75% goes to land when the river is below half median flow and 25% will go to the river. When the river is at higher flows, more treated resource water/wastewater will go to the river.

“Having such a high treatment process means this water, when used on land, is considered a resource and could be used for other purposes including irrigation, growing crops or watering parks and reserves. In fact, we should now call it ‘Resource Water’. As part of our consent application, we’ve also made a commitment to have an adaptive management strategy which will look at ways on how we could reduce the amount of wastewater/resource water entering our plant, and commit to technological improvements to reduce the amount of water entering our awa (river).”

Council sought legal advice in 2021 which confirmed that we must continue to lodge and work on our consent application despite proposed government reforms, as it is a legal requirement of our current consent. The Department of Internal Affairs, which is managing the Government’s water reform, has been an observer at our reference group meetings.

Extensive work will continue over the coming months

Council’s Chief Infrastructure Officer Sarah Sinclair says while officially lodging our consent is a major milestone, there will be a significant amount of work that will be continuing while Horizons’ review our application. In essence, this is the start of the project in a physical sense.

“This work includes continuing to negotiate leases or purchasing land for application sites, more river mixing close to where it enters the river, land testing, daily sampling and analysis, ongoing stakeholder, partners, iwi and community engagement, any legal needs in regards to work for the river or land discharge, cost estimates for land and river discharge sites.”

We will continue to work closely with our community, partners and stakeholders

Throughout this project we’ve worked closely with key stakeholders, iwi and hapu, businesses, the farming sector and our community – including two formal public consultations.

Prior to the September 2021 Council decision, a project steering group had been in place. This group was made up of representatives of Council officers, elected members, and Rangitāne as mana whenua for our city.  Following the council decision in 2021, the steering group was disestablished and replaced with a project reference group. This group includes representatives of Rangitāne, Ngāti Turanga-Raukawa, Rūnanga o Raukawa, Te Roopu Taiao o Ngāti Whakatere, Department of Conservation, Environment Network Manawatū, Federated Farmers, Fish and Game (Wellington Region), Food & Fibre Forum, Manawatū Chamber of Commerce, MidCentral DHB and the Trade and Industrial Waters Forum.

The reference group has been our key group for working on this project at consent development stage. In time we will also be setting up an advisory group for the adaptive management strategy planning. At this point in time, we have not determined the make up of that – but we expect council, business, farming and iwi representation.

Horizons’ Regional Council will now start assessing our consent application

Horizons’ and Palmerston North City Council officers met regularly over the past year, and now that the consent has been lodged, staff will meet in the early new year to go through the application in detail.

Horizons’ may ask for more information, which is not uncommon for large infrastructure projects like this.

The process of reviewing, having hearings, and granting consents can take a long time for large infrastructure projects like this.

Council’s Chief Infrastructure Officer, Sarah Sinclair, says that’s why the application has provided a lengthy period of time for any future treatment to commence, technology advancements and discharge changes to be in operation.

“When we reviewed other consent projects of this scale in our region, they took between 3-5 years to complete. We’ve estimated we may then need several more years to get the necessary building consents and for the associated construction.”

Whilst Council is proposing that the new treatment and discharge could be operating in 2033, these timeframes are determined by Horizons’ Regional Council and the Environment Court if there are any appeals.

Information about Nature Calls will continue to be shared periodically throughout the consenting process, where appropriate. We will continue to share updates to ensure our community and the wider region continues to be involved and informed on this important project.

Updates will be available at www.naturecalls.nz

Factsheet: summary of consent application

We are applying for consents to discharge highly treated wastewater from the new / upgraded wastewater treatment plant to water, land, air and for a new river discharge structure. 

We’re also applying for short-term consents that would mean we can continue to operate our current wastewater scheme past our existing consent expiry in 2028, just in case it takes more time than expected to get our consent application. 

Our application is only related to the discharge and treatment of the wastewater.

Treatment summary

You can watch a video explaining the current treatment here:

The proposed treatment is outlined in a video here: 

The two key significant new steps to our treatment are introducing the removal of nitrogen, which can at high levels affect plant and freshwater life in our awa (river.) The second new step is microfiltration, which will enable us to remove particles as small as 0.04 microns, which are smaller than the human eye can see, and includes things like bacteria and viruses.

On top of existing treatment processes, this will ensure our treated wastewater is so well-treated it can be considered a resource for other purposes – like growing crops, irrigation or watering land. It is still a couple of treatment steps away from drinking water though, so it couldn’t be used for that.

Discharge to river summary

We currently discharge to the Manawatū River all the time, but under our new application we’re proposing to do this less frequently in the future.  We’re proposing that the treated wastewater (or resource water) would be diverted to land when the river is running at low levels, which we typically see in summer. The reason for that is that when river levels are lower, the impact of adding the treated wastewater has more of a chance of having a negative impact on freshwater plants or species.

Currently the treated wastewater, after four days of treatment, enters the river close to our treatment plant on Tōtara Road. In our application, we explain that we’re planning on moving that discharge point to around 4kms downstream, close to Walkers Road. We’re proposing to move the pipe downstream for a few reasons. The first is that the river is deeper and flowing faster at that area, which means the treated water mixes with the river water more effectively and efficiently. That part of the river also hasn’t changed much over the past century, and the final reason is we’re planning on rezoning land to allow for more housing in the western parts of the city and this means that the discharge structure wouldn’t be close to residential areas. We’ve discussed this location with Rangitāne and with Horizons’ engineers.

Map shows locations of existing and proposed wastewater discharge locations

Despite high treatment quality and some wastewater to land, we recognise there are still residual negative effects on the mauri of our awa. Instead of an engineered treatment wetland like we’d earlier considered, Rangitāne have advised us that offsetting the residual effects on the mauri of the awa is more appropriate and another part of the awa environment should be restored.

A location for this hasn’t been confirmed and will continue to be worked on as part of the Adaptive Management Strategy.

Discharge to land summary

We’re going to seek a global consent for the land discharge, which is an approach used for other types of infrastructure projects. This means we are saying that we have identified an area of land that we believe can be used for the discharge of wastewater, rather than specifying certain sections of land. This area can be seen in the image below.

Not specifying land means that Horizons’ will likely need us to supply more information.

For irrigation you need soil that drains well and soil testing in the area we’ve identified has confirmed there are the right soil types for the discharge of wastewater. For the amount of treated wastewater/resource water to be discharged we will need between 500-1200ha of land, and extra to provide setback from sensitive activities and resources such as rivers, lakes and streams, houses, schools, marae etc. This would be the largest land discharge area in New Zealand.

We have had discussions with two landowners in this area which could be ‘pilot’ sites for us to further investigate as we move through the consenting process.

There are a range of options for how the land irrigation/discharge could work – this could include purchasing the land, leasing the land and us managing the operation, or contracting it to the landowner to do it.  It is still early stages and conversations will continue.

Until we identify land for the irrigation, we cannot determine how the resource water could be used- eg for crops/irrigation etc.

We have spoken to stakeholders like Fonterra during this project and will continue to do so.

The area identified as potentially having the right soil types for absorbing treated wastewater.

Adaptive management summary

Our reasons for having adaptive management be part of our consent application are based on three key objectives: reducing the amount of wastewater being discharged into the river and the restoration of natural awa landscapes, enhancing the quality of the treatment of the wastewater over the consent period, and looking at the wastewater as a resource.

As part of our consent application, we have provided an example of an adaptive management strategy, but the actual strategy will be confirmed following the consent being approved. Council and Rangitāne will lead the development of the strategy, but other parties could also play roles. Things that could be included are reducing the amount of wastewater entering our plant, diverting more wastewater to land, if we re-use water then potentially diverting more wastewater from both the awa and land discharge sites, using the water in other non-drinking ways eg: for industrial purposes, looking at new or emerging treatment that could enhance the treatment, and re-using other by-products including for energy of our wastewater plant.

29 September 2022 update

In September last year, Council chose to have the highest treatment currently available in New Zealand and made a commitment to continue to reduce wastewater in the city, and to consider it as a resource. The treated wastewater would be discharged the Manawatū River 75% of the time and irrigated on land when the river is at below median levels.

We’ve indicated we will be lodging our consent application with the regulator, Horizons Regional Council on 31 December 2022. 

From then, the regional council considers and may choose to notify the consent application as part of its process. Council will continue to do significant work during this process.  

River discharge location close to being confirmed  

Over the past few months, we’ve been doing further modelling on the river and have identified a potential location for where the highly treated wastewater could be discharged from. Currently we’re modelling what that environmental impact would be, and then we will be able to confirm it. We’re continuing to work closely with iwi on this work.   

Land work is progressing 

The land component of our consent application is our most challenging element to complete in time for our consent to be accepted. A lot of work is planned for the next three months.  

In our last update we said we’d identified a large area west of the city, close to our treatment plant, which potentially had the right soil types for absorbing treated wastewater [see map below]. We contacted landowners within this area in about soil testing in May and have now been able to test three properties. Those tests confirmed that the area had the soil types previously identified in our desk top assessment.

We stated at the time and will reiterate that where we tested does not mean we want to use those properties for the irrigation. People who own property in the area identified in the map will also be receiving this update. 

The area identified as potentially having the right soil types for absorbing treated wastewater.

A summary of the soil testing written in August is now also available. The 3 types of soil that were tested for are known as Gley, Recent/Raw, and Pallic.

The report states that the best soils for drainage are those that are recent/raw, and that if that soil type is used, we’d need around 600 to 710ha of land, and 75,000m3 for storage. This is less land than we indicated in September 2021. 

Gley soils were the next most effective for drainage, but only 38% as effective as the recent/raw type, meaning they’d require more land. 

Pallic soils were deemed to be extremely restrictive and could pose a high risk of significant cost escalation. 

The report only details testing on 2 of the properties, as the third property was for sale and the testing was done as part of due diligence. The testing showed that property was not suitable for wastewater discharge.

Please note, Figure 3 has been removed from the report as it identifies individual testing locations on private land. As these were given on a voluntary basis by landowners, we want to protect the locations and their individual test results.

Soils Interpretive Report(PDF, 11MB)

We’re looking at applying for a global consent, where we’d get consent for the discharge for a general area, only needing to identify 1 or 2 properties to use as the example for the consent.

This approach would mean we wouldn’t need to procure all 760 hectares needed during the 30+ year consent, in advance of that land being needed. This limits disruption to the farming community. It also means that any potential new Three Waters Agency would be able to determine the best locations based on its needs.  

We are in the final stages of confirming some pilot properties, based on size and soil types, and will be contacting those landowners directly before mid-October.   

We’ll be asking them what their long-term plans are for their properties and if they have any interest in selling or leasing land to us from 2028, when we will need it.   

First look at upgraded treatment plant now available  

Council is committed to having the best treated wastewater in New Zealand, and our proposed methods will have our treatment amongst the world’s best, and just one step away from drinking water.  

There are 2 significant new steps. The first is introducing the removal of nitrogen, which can at high levels affect plant and freshwater life in our awa (river.) The second is microfiltration, which will enable us to remove particles as small as 0.04 microns, which is smaller than the human eye can see and includes things like bacteria and viruses.   

A new video released today shows what our existing treatment plant will look like with these new steps included. Watch it to compare our current processes to our new process.   

This concept video only shows our current proposal, but we’ve also committed to improving the plant or processes if technological advances could further improve the quality of our treated wastewater.   

As part of our consent application, we’re also looking at adaptive management. This includes:   

  • Establishing a framework for managing any environmental risk and uncertainty.  

  • Having a framework for reducing the amount of wastewater generated by the city.

  • A plan for reducing the volume of treated wastewater discharged to the river over the life of the consent .

  • A strategy to establish investigations and actions for the Council to implement over the consent period.

Our project reference group, made up of several stakeholders, technical and iwi representatives is working through this.      

We’ve only got a few more steps before lodging our consent 

With the clock ticking, the next step for our Nature Calls project is to prepare the consent application, pulling together the five years' worth of technical work and assessments. Our reference group will continue to meet and work on the adaptive management strategy.

Due to the impact of Covid-19 on our timeframes, and needing more time for lodging our consent, this week Council brought forward already budgeted money from next year’s Nature Calls budget into this year’s budget. As it was already budgeted money, this has no additional impact on ratepayers.  

While the government is working on the Three Waters Reform, we are legally required to continue with this project as it is a requirement of our consent.  

We will provide another update when we lodge our consent. Once it has been accepted by Horizons Regional Council, we will make it publicly available on our website.

5 May 2022 update

Significant work is underway as Palmerston North City Council prepares to lodge its consent for the future treatment and discharge of its wastewater for up to the next 30 years. 

In September 2021, Council confirmed that it’s future discharge would be a hybrid option, with treated wastewater being discharged to the Manawatū River 75 per cent of the time, and during the remainder of the time a combination of land and river. Council also committed to having the highest treatment in New Zealand. 

Since then, eight major pieces of work required as part of our consent application have gotten underway. These include further modelling of wastewater with various population projections for the next 50 years, monitoring the river water quality and ecology, designing the new additions for our treatment plant, determining the pipe requirements for the land discharge, working on mitigations for any impact on the river or land, finding suitable areas for land discharge

Land testing due to start

Chief Infrastructure Officer Sarah Sinclair says the option requires us to locate land where irrigation could occur, but we don’t need to have purchased the land at the time we lodge consent.

“To identify this land, we need to test soil. We will be doing that west of Palmerston North, including some properties in the Manawatū and Horowhenua Districts. We have selected some properties where we would like to test to give us a good cross section of soil types and will be contacting those landowners. We’ll also be letting people in the community know that we are testing, as we may need to test other sites as well.”

Ms Sinclair says testing land is not necessarily an indication that Council would like to purchase that land.  

“Palmerston North City Council have always said we would like land purchases to be on a willing buyer/willing seller basis, so over the coming years we’d be looking to have those conversations and carry out further testing if needed. If large properties come up for sale in Palmerston North’s west, and close to our treatment plant, then we will consider testing it, and may consider purchasing. We will be working closely with landowners over the coming weeks and months directly as we work through this process.” 

Consent application to be lodged this year

Our wastewater consents expire in 2028. We were due to apply for new consents by June this year however over the past two years there have been significant delays to our work programme due to COVID-19 lockdowns affecting both public engagement, and the wide range of scientific and technical tests needed to prepare our consent application.  

We have advised Horizons Regional Council that it will take us until the end of 2022 to put forward our new consent application. Horizons has acknowledged the likely programme delay and is aware of the significant and complex work that Council have done to develop our best practicable option and progress the consent application. 

This wont affect our ability to design and build the new treatment or discharge requirements in time for the 2028 consent expiry.

Ms Sinclair, says although this is a difficult decision, its one we have to make.  

“We take our legal and environmental responsibilities very seriously, but the pressures placed on our technical teams by the pandemic mean we will not be able to complete important scientific analysis for the modelling of our river for the future, wetland options or land testing by June.  Protecting our environment and ensuring the best outcomes for our community have always been our top priority, and we need extra time to ensure we can do just that.” 

She says Council has informed local and regional iwi and hapu and key stakeholder groups that we would need to seek this extension, and have the support of Rangitāne in acknowledging that the delay is necessary to deliver a complete consent application.  

Stakeholders also continuing to feed into Nature Calls

We have already committed to having the best-treated wastewater in New Zealand, but our Council has also committed to constantly looking at how we can do better over the life of the consent. We’re working with our Project Reference Group and technical experts about how we can do this. The key components include how we will reduce the amount of wastewater over time, reducing the volume of treated wastewater entering the river, how we can re-use components of the wastewater and a strategy for how we will respond to any environmental uncertainty or innovative technology over the life of our consent.  

Our Project Reference Group first met in February and meets monthly to help guide Council officers and consultants about the management and treatment of our wastewater in the future, and feed in ideas for the adaptive management strategy. Having such a diverse range of groups involved means everyone gets to hear each perspective.  

More updates throughout 2022

We will continue to provide our community updates throughout the year, and a deeper look at some of the technical work we are doing.  

All information about Nature Calls is available at naturecalls.nz



Palmerston North City Council has confirmed the 'best practicable option' for managing, treating and discharging the city's wastewater for the next 30 to 50 years.

The selected option will see treated wastewater discharged to both land and river.

Three quarters of the time the treated wastewater will be discharged to the Manawatū River. During the remainder of the time, the discharge of wastewater reduces to the river by 75% and this highly treated wastewater is then used to irrigate crops.

We will also look at diverting a higher proportion from the river over the lifespan of the consent.

The wastewater would also have the best treatment currently available in New Zealand, just one treatment stage down from being drinkable.

Currently the city's wastewater, which is all water that goes down a pipe inside your home or business, is discharged following treatment to the Manawatū River.

Our current consents end in June 2028, however following a consent review 8 years ago Council agreed to bring forward the date for applying for new consents to June 2022. Before that date we need to apply for new consents with our regulator, Horizons Regional Council.

Best practicable option specifics to be confirmed over the next year

Our proposed future management includes discharging to the river approximately three-quarters of the time (based on river flows).

During the remainder of the time, the discharge of wastewater reduces to the river by 75% and this highly treated wastewater is used to irrigate crops. The land discharge will occur all the time when the river flow is below half median, or a flow of 37 cumecs.

City Mayor Grant Smith says Council yesterday voted to cap the amount at 760 hectares of land to give communities some certainty over the amount of land needed. This gives farming, businesses and land owners some surety for their ongoing infrastructure investments.

"We estimate that we will need 760ha of land for irrigation, including buffer zones, within 30 years – when flows are expected to be 35% greater than today. We can plan for growth without changing all the land use on day one. While we will only be discharging to the land some of the time, the irrigation area, once developed, will be 250-plus hectares larger than any existing land treatment site currently in New Zealand, and with the highest treatment. Over the next 9 months we will be able to confirm we have the right amount of land required."

Although we hope the area and type of land needed can be located within the Palmerston North city boundaries and Rangitāne rohe, there is a chance we may need to look at land outside of Palmerston North. We have involved the Horowhenua and Manawatū communities in this project over the past 2 years due to the potential of any of the options affecting their region by river, ocean, or land.

Mayor Smith says Council's preferred approach to acquiring the land will be on a 'willing buyer, willing seller' basis.

"Throughout this process, we will work closely with potentially affected landowners."

The chosen option has indicative capital costs of $426 million dollars and annual operational costs of $7million dollars. We will have a better idea of the exact costs, and impact on ratepayers once the consent application and assessment of environmental effects have been completed and lodged with Horizons' Regional Council.

Read more detail about this option.

Best practicable option was one of the highest scorings in all assessments

Council reviewed more than 800 pages of reports to come to the decision, which is the best practicable option according to the criteria in our current consent. The reports included summaries of public feedback, cost assessments, Māori values, Resource Management Act planning assessments, an assessment of the options against Council's Eco City Strategy and the multi-criteria analysis. This was undertaken earlier in the project to compare options across a range of factors such as cost, public health, environmental impact, cultural values, social and recreation values, infrastructure complexity and resilience, and the ability to provide for growth.

From the technical experts' overall BPO assessment, this was the second recommended option as the BPO. The first recommended option was full discharge to the ocean, but this was not recommended as the BPO as it is completely unacceptable to the community, and also to iwi. These views were given weight as, in determining the BPO, the Council is required to have regard to both adverse effects on the environment, including on cultural values, and take into account Part 2 of the RMA, which includes consideration of the principles of the Treaty of Waitangi.

Extensive community engagement will continue during the next stages

Over the last 3 years community and stakeholder groups in Palmerston North, Horowhenua and the wider Manawatū region have been invited to provide feedback to Council. This has included three rounds of community engagement between 2019 and 2021.

Mayor Smith says Rangitāne o Manawatū, as mana whenua in Palmerston North and part of the project's steering group, have worked closely with Council officers and elected members at both governance and technical levels of the project.

"Engagement with iwi throughout the wider Horowhenua and Manawatū region has also occurred, and significant effort has been made by iwi to incorporate their values into the options assessment and selection process. We will continue to work closely with regional iwi over the coming year to refine and confirm the details of the option and to assess the likely environmental effects as part of developing the consent application."

Council voted to agree a project partnership or governance group to establish an adaptive management strategy to define the resource consent, which would include mana whenua Rangitāne and river iwi.

Role of Three Waters on Nature Calls

The government is proposing that water be managed by four regional entities across the country, with a final government decision pending in the next few months.

Council sought legal advice about whether we should proceed with selecting an option and preparing and lodging the consent applications, given the possibility that any new consents would become the responsibility of the new organisation to implement and manage. The advice recommended we proceed as planned given that the Three Waters proposal has yet to be confirmed, and even if implemented will not override our current legal obligations.

Updates will be provided at key points of the project

Over the coming year, we will continue to provide updates about this project at naturecalls.nz

Best practicable option background

Our BPO sees us removing more treated wastewater from the Manawatū River. We will also look at diverting a higher proportion from the river over the lifespan of the consent.

The option includes discharging to the river approximately three-quarters of the time (based on river flows).

During the remainder of the time, the discharge of wastewater reduces to the river by 75% and this highly treated wastewater is then used to irrigate crops.

While '˜cut and carry' pasture has been assumed in the option proposed, the detail of the crop or crop varieties that will be grown will be clarified during the consent phase over the coming year.

The land discharge will occur all the time when the river flow is below half median, or a flow of 37 cumecs. Irrigating land at this time when soils are drier and crops are growing vigorously will ensure most of the highly treated wastewater and nutrients are beneficially used by the crop, and not lost to groundwater or overland flow. It also means the river will be better able to disperse and dilute the water when we discharge into it.

Over the next year we will be confirming the river and irrigation modelling work and carry out further river monitoring and soil testing.

The option will require soil with good drainage qualities to prevent ponding of treated wastewater. We have not yet identified specific land areas, but these will be selected on a range of factors, including facilitating efficient irrigation operation and land management, limiting the impact on sensitive environments, and minimising the number of landowners affected.

A further agreement under adaptive management was voted on, to engage other reuse and diversion options, to further divert more wastewater from the river in the future. These options could include: repairing infiltration to the city's stormwater network, encouraging more primary treatment of trade waste, developing and recharging wetlands, considering the potential of irrigating on Council reserves, golf courses and race tracks, as well as reducing domestic water use.

The final consent application will identify some of these further diversion and reuse opportunities, and others will be added over the lifespan of the consent as new technologies become available and regulations change.

An adaptive management strategy will be developed and form part of our consent application. This means Council and key stakeholders will work together throughout the development of the consent to ensure the best results for our discharge environments, and will plan to take into account new technology and other reuse and diversion of wastewater options.