Te Awarua-o-Porirua Harbour and Catchment Management Programme

Image showing Porirua Harbour and Pauatanaui Inlet.

This page describes the Porirua Harbour and Catchment Management Programme, and has reports, a literature review, and research documents and maps about the Harbour and Catchment.

On this page:

 

Latest news and FAQs on their own pages

For the latest news and items of interest, please go to our Porirua Harbour and Catchment NEWS or Frequently Asked GENERAL QUESTIONS pages under Community Projects.

Healthy Streams and Harbour - Have Your Say

The Te Awarua-o-Porirua Whaitua Committee being run by Greater Wellington Regional Committee, is now seeking public input on what people value and want for the harbour and streams entering it. The Committee will be running public meetings at a range of venues over February-March for face-to-face discussion and to gather similar information. An online survey is also available here for anyone to have there say about what is important to them about their enjoyment and use of our streams and the harbour. 

Stormwater Bylaw and Car Washing

The Council is preparing a community information series (hard copy and online) on practical aspects of the new Stormwater Bylaw and other ways in which people and businesses can help clean up our streams and harbour. A 'Question & Answer' sheet on car washing has now been produced and can be accessed here.

Stormwater Bylaw

In an effort to reduce contaminants entering Porirua Harbour and tributary streams, Porirua City Council introduced a Stormwater Bylaw in August 2015 prohibiting the all too often tipping, spilling, and washing of a number of common contaminants into storm drains:

  • Cleaning products and agents - e.g., detergent, disinfectants, bleach, '30 Seconds'
  • Water blasting waste
  • Paint
  • Solvents
  • Liquid fuels - e.g. diesel, petrol oil, grease
  • Radiator coolant
  • Cooking oil
  • Cement wash and slurry, and concrete cutting waste.

This combines with other joint Council's actions to reduce other contaminants getting into our harbour, including:

  • A catchment-wide sediment reduction plan
  • Tightening rules around earthworks
  • Relocating the 'Take Charge' business education and monitoring programme to Porirua
  • School environmental education programmes
  • Multi-million dollar stormwater and sewer upgrade and repair to eliminate overflows and leakage.

A 2014 study of Porirua Harbour catchment residents showed that 65% of people were either unsure or did not know that stormater drains did not go to treatment, but instead into the nearest srream and into Porirua Harbour. The cumulative impact of 80,000 people tipping, washing, flushing and spilling  contaminants ino the stormwater system is considerable.

The Council will be undertaking a community education programme to explain the Bylaw, and provide guidance about it's implications and the eco-friendly ways people can deal with the contaminants listed and others. In the meantime here is a link to a a couple of neat videos on stormwater contaminants and carwashing from our 'Tazzie' neighbours.

Te Awarua-o-Porirua Whaitua Committee established

In September 2014 Greater Wellington Regional Council announced that it was establishing a Whaitua Committee for Te Awarua-o-Porirua Harbour catchment.

Whaitua are the Regional Council's response to implementing the Government's new National Policy Statement on Freshwater Management (NPS-FM). The Porirua Whaitua is one of five covering the major catchments of the Wellington region. The Whaitua will work with local communities to establish freshwater quality and quantity standards that reflect local values and aspirations for its catchment and streams. These will then be incorporated into the review of the Regional Plan to recognise local variations. The Whaitua will recognise that the catchment and streams are the major contributor to the state and health of Porirua Harbour and also reflect the community aspirations for the coast too. A fundamental document in informing the Porirua Whaitua process is the Te Awarua-o-Porirua Harbour and Catchment Strategy and Action Plan.

Visit the Regional Council's Whaitua webpage which has more information and an excellent explanatory video on the Whaitua.

Follow-up Bathymetric Survey Shows Interim Sediment 'Improvement'

Surveyors from marine specialists DML check plots lines for measuring harbour depths.

Surveyors from marine specialists DML check plots lines for measuring harbour depths.

Comparison between a November 2014 bathymetric survey and the benchmark 2009 survey of Te Awarua-o-Porirua Harbour shows much lower sedimentation rates occurring in the harbour in the last 5 years.

The report - Te Awarua-o-Porirua Harbour: Report of Survey & Verification of Sedimentation Rates (2015) - results from the scheduled 5-year follow-up survey from the original comprehensive 2009 survey and report which was a key part of the research towards restoration of the harbour. 

The study found the sedimentation rate for both the Onepoto and Pauatahanui arms of the harbour was 2mm per year on average. That is significantly lower than those calculated for the 1974-2009 period (35 years) of 5mm per year and 9mm per year respectively.

“While this is good news for the past five years, caution is required when interpreting these rates,” said Porirua City Councillor Bronwyn Kropp. Ms Kropp is also chairperson of the Te Awarua-o-Porirua Harbour and Catchment Joint Committee, which is tasked with overseeing implementation of the Porirua Harbour and Catchment Strategy and Action Plan 2012.

“These new rates will be a combination of natural variations and a lack of major storms over the past five years that would normally deliver more sediment to the Harbour" she said.

“Future surveys will determine more accurately what any sustained long-term reduction is, but these results are encouraging.
“It is extremely gratifying to know that the hard work put into the Harbour by Councils, Iwi and Community is starting to show results. Reducing sedimentation is a slow process but we can take heart. Recently the Porirua Harbour Trust released a positive annual scorecard for the harbour and last year’s The Guardians of Pauatahanui Inlet cockle survey was also good.

“We are seeing tentative, but positive, overall trends towards improvement in Te Awarua-o-Porirua Harbour’s health.”

View the Te Awarua-o-Porirua Harbour: Report of Survey & Verification of Sedimentation Rates (2015). (pdf)


Harbour Strategy governance group established

The first formal meeting of the ‘hands on’ governance group for the Porirua Harbour Strategy was held on 26 August 2014. The Te Awarua-o-Porirua Harbour and Catchment Joint Committee (Joint Harbour Committee) provides oversight of the implementation of the Porirua Harbour and Catchment Strategy and Action Plan, particularly the work of the three Councils involved.

The 5-person Committee comprises appointed representatives from Porirua City Council, Ngati Toa Rangatira, Wellington City Council and Greater Wellington Regional Council that monitors and reviews implementation activities for the Harbour Strategy.

Following the October 2016 local body elections, the Committee is Chaired by PCC Councillor Anita baker, the other committee members are Cr Kylie Wihapi (PCC), Taku Parai (Chair of Te Runanga o Toa Rangatira), Cr (to be confirmed) (WCC) and Cr Barbara Donaldson (GWRC). Each member reports back to their respective Council or Runanga.

The Joint Committee has the authority to ask for reports on particular aspect of harbour and catchment issues, Strategy implementation or Council activities.

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First Porirua Harbour catchment 'Environmental Perception Survey'

A report from the first Porirua Harbour Catchment Environmental Perception Survey was released on 26 August 2014. The report follows from a March/April telephone survey of 600 respondents from across the harbour catchment, and different age and ethnic groups.

The Survey report makes interesting reading, but the broad results show that:

  • the community overwhelmingly supports cleaning up the harbour;
  • however, they feel they don’t have enough information about what’s happening;
  • the community generally has good habits around disposal of domestic waste, with the marked exception car wash water;
  • litter is perceived as the single greatest threat to the harbour, with sewer and stormwater a close second;
  • the majority do not know that street drains go to stream/harbour rather than treatment;
  • the majority want to be more involved but need to know more about how;
  • The survey canvassed people’s understandings, attitudes and behaviours towards the Harbour and streams. And will be used to guide development of future community engagement and educations programmes. Follow-up surveys will monitor the success or otherwise of these education programmes and any appropriate adaptations made.

The joint Councils and Runanga are now considering a range of methods to improve communication of key information and messages to the different communities within the catchment. The recent series of posters in the Kapi Mana News and The Wellingtonian is one response the Survey findings: Aimed at the general public in a large, interesting and attractive format with succinct but clear messaging.

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Official renaming of Porirua Harbour

From 1 August 2014 the Porirua Harbour has a new official name. The New Zealand Geographic Board gazetted and publicly notified a number of name alterations and changes for geographic features of Porirua Harbour and catchment. The changes resulted from the Ngati Toa Rangatira Claims Settlement Act 2014.

The common use, but unofficial names, 'Porirua Harbour' and 'Porirua Harbour (Pauatahanui Inlet)' are now replaced by 'Te Awarua-o-Porirua Harbour'. In practice the two arms of the harbour will be known or labelled as Te Awarua-o-Porirua Harbour (Pauatahanui Inlet) and Te Awarua-o-Porirua Harbour (Onepoto Arm)

View Full Notice 

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Porirua Harbour posters

The first of a series of four posters promoting community actions to help improve the health of the harbour and streams was released 1 July 2014  through the 'KapiMana News' and 'The Wellingtonian'.

They are part of implementing the Porirua Harbour and Catchment Strategy and Action Plan. The posters introduce brief key messages about how people can help improve water quality in our streams and the harbour.

The full-colour posters feature the following messages:

Image of Poster1 - Catchment area

Poster 1 -
Where exactly is the Porirua Harbour catchment  

Image of Poster 2 - Everything we wash

Poster 2 -
Protecting our street drains from pollutants  
 
Image of Poster 3 - Everything we drop 

Poster 3 -
What to do with household pollutants 
 

Image of Poster 4 - 24hr hotline

Poster 4 -
Use the 24hr Environment Hotline 
 


The posters are part of a joint effort by the Councils and Runanga Porirua Harbour Strategy Implementation Team and one element of a wider community education strategy.

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Significant Inlet health improvement - Cockle Survey results

The results from the December 2013 Pauatahanui Inlet Cockle Survey showed a steady improvement in the health of the cockle population and the Inlet ecology.

The Cockle Survey is undertaken every three years by GOPI (Guardians of Pauatahanui Inlet) and analysed by NIWA. The results show that the cockle population has steadily increased in size since 2001. "In fact it has increased by 21% since 2010, 60% since 2001, and 87% since 1995. This is good for the cockles, but must also be an indication that the general ecological health of the inlet is improving," said GOPI spokersperson Professor John Wells.

A significant effort is going in to reducing contaminants and sediments entering Porirua Harbour, including the inlet, particularly with the completion and implementation of the Porirua Harbour and Catchment Strategy and Action Plan in 2012.

Professor Wells says, "The actions taken by Greater Wellington Regional Council, Porirua City Council, farmers and urban developers to drastically reduce the amount of sediment entering the inlet is undoubtedly having a positive effect. Let's hope that this trend will continue at the same pace into the future."

The full Cockle Survey can be viewed on the GOPI website.


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First environmental 'Scorecard' released

The Porirua Harbour Trust released its first 'Scorecard' assessing the implementation of the Porirua Harbour Strategy and general harbour health. The 14 February 2014 report contained many positives, and a few negatives.  A panel of experts assessed a number of aspects of the harbour and the implementation of the Porirua Harbour Strategy, including the following: Agency action, sedimentation, recreational useage, ecological health and waste.  The Scorecard is produced annually every February.

The first Scorecard acknowledged that while it was early days in the implementation of the Porirua Harbour Strategy that: sedimentation rates continued to be a concern, recreational users were happier with harbour health; while litter remained an issue, despite significant improvements.

The assessment panel is made up of Grant Baker - Chairperson of the Porirua Harbour Trust; Lindsay Gow - Trustee; Dr John McKoy - Chairperson of Pauatahanui Inlet Community Trust; and Clive Anstey - Landscape and resource planner.

The full report can be viewed on the Porirua HarbourTrust website.


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Porirua Harbour habitats survey

A 12 February 2014 report on the results a habitat survey showed that sediment entering the harbour continued to be a problem. Thet five-yearly survey of Porirua Harbour intertidal habitats showed that the area of estuary covered in freshly deposited mud had increased substantially, particularly near the Kakaho and Horokiri streams.

Soft mud reduces the water clarity, the amount of oxygen in the sediment, and the growth of vital seagrass. This results in a loss of habitat, reduces recreational and aesthetic values and the estuary’s ability to function effectively.

The density of seaweed growth near the mouths of the Porirua, Pauatahanui and Horokiri streams was evidence that nutrient inputs (nitrogen and phosphorus) remained high. Seaweed mats can smother sediment and seagrass. When the seaweed dies it starves the sediment of oxygen and causes black smelly mud.

Although there were large, healthy areas of saltmarsh in the eastern Pauatahanui Arm, saltmarsh was absent in the Onepoto Arm of the harbour. Saltmarsh areas are highly productive, provide valuable habitat for fish and birds, and offer flood and erosion protection.

"This was only the second habitat mapping survey in Porirua Harbour, the findings confirmed that important habitats such as seagrass and saltmarsh remain vulnerable to the effects of human activities on land” said Greater Wellington Regional Council’s Coastal Scientist, Dr Megan Oliver. “Sediment and nutrient inputs from the surrounding land and waterways are reducing sediment quality, biodiversity and healthy functioning of the estuary”.

Greater Wellington Regional Council commissioned the second broad scale habitat mapping survey of the intertidal area to assess the changes in key estuary habitats (eg, saltmarsh and seagrass) and substrate (eg, areas of mud and sand). The survey information feeds into the Porirua Harbour and Catchment Strategy and Action Plan sediment reduction and estuary restoration work. It also helps focus policy and management decisions related to land-based activities.

View the Porirua Harbour Broad Scale Habitat Mapping 2012-13 Report.

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 Harbour Strategy wins awards

2013 - The Porirua Harbour and Catchment Strategy and Action Plan was announced as the '2013 Best Practice Consultation and Participation Award' winner by the New Zealand Planning Insititute on 2 May 2013.

Mayor - NZPI Award

The NZPI's Annual Conference in Hamilton named Porirua City Council, Ngati Toa Rangatira, Wellington City Council and Greater Wellington Regional Council as joint winners for their collaborative effort and public consultation in the development of the Harbour Strategy.

The NZPI Awards panel considered that, "the outstanding collaborative effort involved in addressing major issues relating to one of New Zealand's iconic harbours to be worthy of this best practice award... [and] believes that the development of the Strategy demonstrates how a best practice consultative approach transcends the limitations that a non-statutory document often has."

 

2012 - The Porirua Harbour Strategy Coordinator, Keith Calder, was announced as the the winner of the Wellingtonian of the Year in the Environment category at the 22 November 2012 Award dinner. The Award recognised that after 4-and-a half years coordinating and driving the development of the completed Porirua Harbour and Catchment Strategy and Action Plan this was a fitting recognition and conclusion to the first phase of the Strategy programme. The 'Welly' acknowledged Keith's contribution to the development of the ground-breaking Strategy. This involved new management approaches and use of best practice consultation in the content and development of the Strategy.

Keith Calder - Wellingtonian of the YearKeith Calder receiving his 'Welly Award' on 22 November 2012 from Dr David Prentice, Chief Executive of Opus NZ.

Keith said that he strongly believed the Award was a reflection of the commitment of the Council, Runanga, other agencies and the team of people directly involved. "The effort and quality of the work done by the Strategy team have made me look good." says Keith. 'I accept the Award not just for myself, but for a project and a project team that also warrant this recognition."

Keith was also grateful to the three councils and the Runanga that supported the work of the team. Particular thanks to previous Porirua Mayor, Jenny Brash, current Mayor, Nick Leggett, Greater Wellington Chair, Fran Wilde, and Wellington Mayor, Celia Wade-Brown each of whom had created a significant political and public momentum behind the Strategy.


2012 - The Porirua Harbour and Catchment Strategy and Action Plan won the 2012 Geok Ling Phang Memorial Award for the project's "significant contribution" in the Wellington region.

The Award came from the Wellington branch of the New Zealand Planning Institute and was presented on 8 November 2012. "This is an acknowledgement, on a regional level, of best practice multi-agency partnerships and an integrated approach to catchment and estuary management planning."

The strategy was recognised because it highlighted the valuable contribution sound planning makes to the quality of where we work, live and play and it addresses current needs and those of the future, says Phil Gurnsey, Wellington Planning Institute Branch Chairperson. "The Strategy is a worthy recipent of this Award on World Town Planning Day. It demostrates significant community buy-in and the benefits of planned consultation in achieving a shared vision for the Porirua Harbour".

Geok Ling Phang (nee Lee) was a Wellington town planner who tragically died in an accident in 2009. She was a cherished wife and loving mother of three children.

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Strategy Implementation Update - 2014

It might not have been immediately obvious, but a lot of work had been happening in the background as part of implementing the Porirua Harbour Strategy. These will be progressively reported on as elements of this work are completed or become more evident through news media. Some of the 'big ticket' items outlined in the Strategy and underway, included the following:

  • Sewer and stormwater upgrades. PCC was well underway with a $20M, 10year upgrade of existing sewer networks and other remedial stormwater work. Work on connecting Pauatahanui village to sewer mains was commenced at the end of 2013 and completed mid-2014.
  • Community, Business & School Education Programme. A mulit-faceted, and multi-agency collaborative programme was developed and progressively implemented.
  • Porirua Stream Mouth and Estuary Enhancement Plan. Developed by consultants and community groups and finalised March 2015.
  • Catchment Sediment Reduction Plan. Key research elements had been completed to identify critical areas where sediment and erosion stabilisation is essential. This information has enabled development of a prioritised sediment reduction plan for the entire catchment. The plan will be completed in by August 2015 and guide future Council programmes. Part of programmes development will identify opportunities for public participation.
  • Fish Survey. Ngati Toa Rangatira and NIWA completed an oral history, a literature search, and a harbour-wide fish survey and a shellfish survey of the Onepoto Arm to complement the existing triannual Pauatahanui Cockle Count. This both the survey and cockle count will form a baseline with which to guage biological trends in the harbour as the Strategy is implemented and will guide aspects of the estuary restoration.
  • Regulatory review. The Regional Natural Resources Plan has been reviewed and ready for public notification. This will have a significant bearing on the management the resources of the harbour and catchment, and ultimately guide subsequent reviews of district plans that govern land uses. There are a number of other statutory and non-statutory plans or guidelines either underway or planned that will improve management of catchment areas.

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Land And Water Aotearoa (LAWA)

LAWA is a new publicly available data base on the quality and quantity of waters available in over 1200 stream in New Zealand, including our own Porirua, Horokiri and Pauatahanui streams. together environmental monitoring data fr

Initially a collaboration between New Zealand’s 16 regional and unitary councils, LAWA is now a partnership between the councils, Cawthron Institute, Ministry for the Environment and Massey University and has been supported by the Tindall Foundation.

 

The intention of setting up this site is to help local communities find the balance between using natural resources and maintaining their quality and availability.

 

At the moment, you can view data about the quality of our country’s freshwater. In time, other data on our coastal, land and air resources will be added.

 

Check it out at www.LAWA.org.nz.

 

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Te Awarua-o-Porirua Harbour - the Centrepiece of the City

Te Awarua-o-Porirua Harbour, comprising the Onepoto Arm and the Pauatahanui Inlet, is considered by Council and community as the centrepiece of the City. The Harbour is the largest estuary system in the lower North Island. As well as having a nationally significant wildlife area, the estuary has cultural, recreational, economic (transport), and other wildlife habitat values.
 
Porirua City Council appointed a Porirua Harbour Strategy Coordinator in 2008 and is the lead agent in the Porirua Harbour programme along with key partners Te Runanga o Toa Rangatira, Wellington City Council and Greater Wwellington Regional Council. The partners completed the development of the multi-agency Porirua Harbour and Catchment Strategy and Action Plan in 2012 aimed at Harbour protection and restoration, and are now committed to Strategy implementation. An annual report is made to Councils and the Runanga in August/September on progress on implementing the Strategy.
 
The Strategy development programme involved four phases and the following timetable:
  • Partnership – forming partnerships with key agencies and organisations – 2008-10
  • Research – a targeted research and monitoring programme - 2008-10 (now ongoing research and monitoring)
  • Planning – public strategy development and preparation process – 2008-11 
  • Implementation – 2012 onward

This has been followed by the first three-year review and revision of the Strategy and Action Plan over 2014-15

The Council and key partners have continued an existing work programme for restoration planting and a landowner advisory service aimed at reducing catchment erosion and improving stream water quality.
 
The Council and key partners have also developed or are reviewing a number of policy and programmes that will benefit harbour protection and public enjoyment that includes:
  • Scheduled reviews of the Regional Strategy and the Regional Natural Resources Plan that reflect the significance of Porirua Harbour and the Harbour Strategy
  • Upgrade of strategic infrastructure assets (stormwater, sewerage, water reticulation and landfill)
  • A whole-of-catchment Sediment Reduction Plan
  • A review of options and opportunities for direct estuary restoration programmes
  • Porirua Stream Mouth Estuary Enhancement Plan
  • Targeted research and monitoring
  • City Centre Revitalisation
  • Plan changes - Pauatahanui-Judgeford Structure Plan and the Northern Growth Corridor Structure Plan
  • Harbour walkway development
  • A trade waste bylaw

In 2014, improved governance to oversee the implementation of the Harbour Strategy wasn provided by the establishment of a Te Awarua-o-Porirua Harbour and Catchment Joint Committee comprising representatives from the four key stakeholders.

In 2015, the Te Awarua-o-Porirua Whaitua Committee wa established by Greater Wellington Regional Council. This Committee is responsible for developing stronger statutory protection of the values and qualities of Porirua Harbour and waterways for inclusion in the Regional Natural Resources Plan. The Committee is consulting with the Councils and community and likely to report back to the Regional Council in 2017.

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Aerial Photo

Thumnbail image of aerial view of Porirua Harbour.

This image shows the sandbank development in the harbour and illustrates the kind of urbanisation and roading networks that are a constant challenge to the use and quality of harbour waters.

View full size image in new window, or download as a one page pdf file for printing.

Caption: A composite and enhanced image of Porirua Harbour using 2002 aerial photographs (Courtesy of Geographx (NZ) Ltd)

 

 

 

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Porirua Harbour and Catchment Literature Review

Online access is available to two documents recording, analysing and summarizing published information on the physical and natural history and condition of Porirua Harbour and it's catchment. The work was commissioned by Porirua City Council with Wellington City Council support, and took consultants Balschke and Rutherford over 12 months to compile, analyse and write.

The Review comes in two parts:

  • The main report (100 pages), 'Porirua Harbour and its Catchment: A literature summary and review' which provides a summary and analysis of an extensive range of scientific papers and reports, and arranged within resource management themes. One sections undertakes some comparison of Porirua Harbour with other estuaries around New Zealand;
  • A separate appendix (45 pages), 'Porirua Harbour and its Catchment: Appendix 2 - an annotated bibliography' which compiles all references from the main document, gives the nature of the document and describes the main points from the document.

The literature review summarises not only "what we know" about the Harbour and catchment, equally importantly, highlights the gaps in knowledge and provides an extensive list of reserach priorities for the future. This will assist in shaping future research programmes and research partrnerships for Porirua Harbour.

The executive summary concludes:

The body of research about Porirua Harbour and catchment has grown considerably in the last decade. Research on the Onepoto Arm and its catchment has been much less than that on Pauatahanui Inlet and catchment but has increased significantly in the last five years. Knowledge and understanding of the Outer Harbour is still very limited.

From a whole harbour and catchment perspective, there is reasonable knowledge of the physical environment and environmental history, and of terrestrial, freshwater and estuarine habitats and macroscopic biota. There have been a number of studies of water and sediment quality but our understanding of the causes of some significant water quality problems is still very limited. Harbour sedimentation rates have been studied in detail, but a full understanding of the catchment-harbour and harbour-ocean sediment transfer system is hampered by poor knowledge of the variability of sub-catchment sediment production and transfer processes, and of harbour hydrodynamic and exchange processes. A particular issue for integrated catchment management is the effects of the roads and other hard surfaces that encircle Porirua Harbour, to a degree that is unique in New Zealand. This issue needs to be better understood.

Both reports are available at the links listed under the General section below.


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Porirua Harbour Literature Library

The literature identified in the (above) literature review is now publicly available as hardcopy or electronically at Porirua Public Library. As part of a Master of Environmental Management practicum, student Gareth Kear undertook search and collation of this new resource under the supervision of review author, Paul Blaschke, Harbour Strategy Coordinator, Keith Calder, and local history Librarian, Ruth Barrett.

In conjunction with the literature review, the collection will provide an invaluable and easily accessible resource for the public, officials and researchers at the local and national level.

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Harbour and catchment research

Porirua City Council and Te Runanga O Toa Rangatira with support from Greater Wellington Regional Council, Wellington City Council, and the Pauatahanui Inlet Community Trust are committed to ongoing critical research that identifies and monitors the biophysical condition of the Harbour and catchment. A series of annual and longer term research projects are underway to monitor changes with the harbour.

Projects completed or ongoing since 2009 include the following:

  • 'Fine Scale Monitoring' assessed the ecological health of selected locations in the Harbour by analysing sediment nutrients, toxins and biota;
  • 'Broad-scale Habitat Mapping' assessed the sediments and habitat within intertidal areas of the Harbour;
  • 'Ecological Restoration Priorities for the Porirua Stream and its Catchment' identifies the native species and habitat in this extensive stream system, the threats to these and other natural resources, and recommendations for ecological restoration.
  • 'Porirua Stream: your stream, your catchment' provides a easy-to-read summary brochure of the main 'Ecological Restoration Priorities' report above. It also provides a lift-out 'Best Bets' planting guide of restoration plants.
  • 'Porirua Harbour Bathymetric Survey' for 2009 and the follow-up survey of 2014, describe the processes and results of the most comprehensive and accurate surveys of the Harbour's seabed.

 

  • 'Patterns and Rates of Sedimentation within Porirua Harbour'. The 2009 report compares the 2009 bathymetric survey with previous surveys dating back to 1849. Particular analysis of sedimentation changes between the 1974 survey and today.
  • 'Patterns and Rates of Sedimentation within Te Awarua-o-Porirua Harbour'. The 2015 report compares the 2014 bathymetric survey with the previous 2009 survey.
  • 'Porirua Harbour Targeted Intertidal Sediment Quality Assessment' provides more detailed assessment of some specific areas of contamination.
  • 'Porirua Harbour Intertidal Macroalgal Monitoring' analysis of the coverage and significance of algae growth (predominantly sea lettuce - Ulva) within the Harbour.
  • 'Stormwater Contaminants in Urban Stream in the Wellington Region' includes and has significant reference to the Porirua Stream.

 

  • Porirua Harbour Subtidal Sediment Quality Monitoring records the results of the November 2008 survey.
  • Sedimentation Zones and Rates within Pauatahanui Inlet and the Onepoto Arm of Porirua Harbour identifies sedimentation rates in localised zones covering the whole harbour to assist with catchment modelling in 2011.
  • Porirua Harbour - Assessment of Effects on Hydrodynamics from Proposed Dredging looks at the effectiveness and physical sustainablity of strategic localised dredging in Pauatahanui Inlet.
  • Porirua Harbour's Sediment Problems: causes and solutions was a presentation summarising harbour research over 2011 and its implications for harbour and catchment managment.
  • A Seagrass Restoration Assessment was completed by NIWA in May 2012 and identify the possibilities and priorities for seagrass planting.

 

  • A Fish Survey is a joint effort between Ngati Toa Rangatira and NIWA. It involves several stages starting with a literature search, oral history and concludes with field surveys of fish and shellfish numbers.
  • Community Environmental Perception Survey undertaken by the joint councils to establish awareness, attitude and behviours of the communities within the Porirua Harbour catchment. This baseline survey was done in March 2014 and the report completed late April. It will inform community education programmes and subsequent yearly surveys will enable assessment of the success of these programmes. The Survey report will be publicly available in August once Councils have considered it's implications for future harbour programmes.
  • Pauatahanui Inlet Cockle Survey December 2013 Report shows a significant progressive improvement in cockle numbers and Inlet health.
  • Te Awarua-o-Porirua Harbour: Report of Survey & Verification of Sedimentation Rates 2015. Indicates that sedimenation rates have been lower in both arms of the harbour over the past 5 years since the 2009 survey.
  • Te Awarua-o-Porirua Catchment Sediment Reduction Plan 2015. Outlines the range of current or planned actions by the three Councils to reduce sediment entering the harbour. A key element of the Harbour Strategy.

These reports highlight a number of critical aspects about the biophysical condition of the Harbour and catchment:

  • The key and most significant threat to the condition and future of Porirua Harbour is excessive sediment accumulation, particularly in Pauatahanui Inlet
  • Moderate levels of heavy metal contamination in areas of the Onepoto Arm, largely from roading and storm water systems.
  • Pervasive and spreading nuisance algal growth throughout the harbour is an indicator of nutrient enrichment problems
  • A significant limiter to seagrass restoration is high nutrient levels in both arms of the harbour
  • Significant opportunities to improve stream quality affected by sediment and contaminants
  • Despite these challenges, the Harbour still has the basis of a sound ecology that would benefit from reductions in sediment, contaminants and nutrients entering the Harbour.
  • Dredging will have little impact on improved harbour flushing and have limited durability. Ancilliary information strongly suggest that initial and ongoing dredging costs would be prohibitive, that ecological impacts would be severe, and resource consents would be difficult to obtain.
  • Reducing sediment inputs from rural erosion and urban development within the catchment is the key to protecting and improving the health of Porirua Harbour. Reducing sedimentation rates provides the greatest 'co-benefits' as it has the greatest impact on harbour flushing, contaminant transportation and harbour ecology.

The reports are available to view from the links below.

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Porirua Harbour Bathymetric Chart 2009

Porirua Harbour Bathymetric Chart 2009.

This chart shows the half metre contours within the Porirua Harbour derived from the bathymetric survey undertaken in March/April 2009. The scale on the bottom right of the chart indicates the depth of each contour.

 

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Photo Story - 'A Day in the Life of Porirua Harbour'

A short video showing a Day in the Life of Porirua Harbour (3.37mins via YouTube) produced by Keith Calder, Porirua Harbour Strategy Coordinator at Porirua City Council.

 

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Links to more information

Porirua City Council Links

Regional Reports

Strategy and Action Plan

Public Seminar Presentations

Please note: some of these files are quite large, and have full colour maps and diagrams.

Community Surveys:

Sedimentation:

Silt and Sediment Control on Small Building Sites:

Contaminants:

Nutrient Enrichment:

Ecology:

General:

External websites

Physical conditions

 

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Contact Details

For enquiries or more information about the Harbour programme, please contact:
 
Keith Calder
Porirua Harbour Strategy Coordinator
Porirua City Council
PO Box 50218
Porirua City 5240
Phone: (04) 237 5089
Email: kcalder@pcc.govt.nz