Porirua Harbour and Catchment Management Programme
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.
Latest news now moved to its own page
For the latest news and items of interest, please go to our Porirua Harbour and Catchment News page under Community Projects.
Strategy Implementation Update
It might not be immediately obvious, but a lot of work is 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, include the following:
- Sewer and stormwater upgrades. PCC is well underway with a $20M, 10year upgrade of existing sewer networks and other remedial stormwater work. Work on connecting Pauatahanui village to sewer mains will commence before the end of 2013.
- Community, Business & School Education Programme. A mulit-faceted, and multi-agency collaborative programme is being developed and will be progressively implemented over the next year
- Estuary Restoration Framework. This is being developed by a consultant and community groups. It is hoped to have this finalised mid 2013.
- Whole of Catchment Revegetation Framework. Key research elements are nearly complete to identify critical areas where sediment and erosion stabilisation is essential. This information will enable commencement of developing a prioritised and targeted revegetation programme for the entire catchment. There will be plenty of opportunity for public participation.
- Fish Survey. Ngati Toa Rangatira and NIWA are proceeding with the third and final stage of a harbour-wide fish survey. This will form a baseline with which to guage biological trends in the harbour as the Strategy is implemented and guide aspects of the estuary restoration.
- Regulatory review. The Regional Plan is under review. 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.
Porirua Harbour and Catchment Strategy and Action Plan Launched
The final Porirua Harbour and Catchment Strtaegy and Action Plan was publicly released on Tuesday 24 April 2012. A separate article can be seen on the Porirua Harbour and Catchment News page (Link above).
You can view and download the documents from the links below.
Draft Strategy Hearing Committee Report Adopted
In the weeks leading up to Christmas, the report and recommendations of the joint Hearing Committee that considered submissions on the draft Porirua Harbour and Catchment Strategy and Action Plan were fully adopted by three councils and the local Runanga.
The 19 page report addresses a range of topics raised by 23 submitters to the draft Strategy – describing each issue, recommendations in response and an explanation for the Committee's decision.
The Hearing Committee comprised delegates from Te Runanga O Toa Rangatira (Rawiri Faulkner, who acted as chair), Porirua City Council (Cllr Liz Kelly), Wellington City Council (Cllr Ngaire Best) and Greater Wellington Regional Council (Cllr Barbara Donaldson). The Committee reported back to councils and the Runanga in November following submissions in September and hearings in October. The report was considered and adopted by councils and the Runanga in separate meetings over December.
The appropriate changes are being made to the Strategy documents and the final Strategy is likely to now be released in April.
In the meantime, the councils, community groups and other agencies involved in developing the Strategy continue to progress implementation of the Strategy and associated action plan:
- Current council policy and practice with respect to sediment and pollution control and infrastructure operation and maintenance is being reviewed;
- Critical research activities for the past year are near completion and will enable, in particular, the development of a prioritised whole-of-catchment re-vegetation plan and an estuary re-vegetation plan;
- A community- and business-specific communications plan will be developed in the next few months aimed at helping people to understand issues threatening the harbour and how they can assist its clean-up.
- Additional funding is being sought through the Long-Term Plan process for new key activities identified in the Strategy and Action Plan.
Copies of the Hearing Committee's report have been sent to all submitters to the draft Strategy.
Draft Porirua Harbour and Catchment Strategy and Action Plan completed
On Thursday 24 August 2011, Porirua City Council endorsed a draft Porirua Harbour and Catchment Strategy and Action Plan for public release and submission.
The multi-agency Strategy has been 3 years in the making and is intended to provide a framework for and schedule of coordinated and targeted action to restore the health of Porirua Harbour and its contributing streams. Led by Porirua City Council, the other three key stakeholders, Wellington City Council, Greater Wellington City Council and local iwi, Te Runanga O Toa Rangatira, along with eight other local, regional and national agencies such a the Department of Conservation, have all been involved in the Strategy development.
A preliminary draft was endorsed by Greater Wellington Regional Council in mid June. Wellington City Council endorsed the Draft Strategy on 18 August 2011. The Strategy was publicly notified at the end of August, with a closing date for submissions of 30 September.
Copies of the Draft Strategy and a Detailed Action Plan supplement were available at council offices and libraries. A mailing list of local and regional interest groups were sent copies of the Draft Strategy and the Detailed Action Plan supplement.
The attractively presented Draft Strategy outlines the history and significance of Porirua Harbour and the Strategy, and the three key objectives for restoring the harbour - reduce sedimentation, reduce pollutants, and ecological restoration.
Porirua Harbour is the Centrepiece of the City
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 has appointed a Porirua Harbour Strategy Coordinator and is the lead agent in the Porirua Harbour programme and committed to developing and implementing a Harbour and Catchment Strategy aimed at Harbour protection and restoration.
Porirua City has initiated a strategy development programme with partners Te Runanga O Te Rangitira, Greater Wellington Regional Council and Wellington City Council (70% of Porirua Stream catchment is in the Wellington City district), involving 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
Planning – public Strategy development and preparation process – 2008-11
Implementation – 2010 onward
The Council will continue an existing work programme for restoration planting and a landowner advisory service aimed at reducing catchment erosion and improving stream water quality.
The Council has also developed or is reviewing a number of policy and programmes that will benefit harbour protection and public enjoyment that includes:
Review of strategic infrastructure assets (stormwater, sewerage, water reticulation and landfill)
Storm Water Action Plan
City Centre Revitalisation
Porirua Development Framework
Harbour walkway development
Trade waste bylaws
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.
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 in 2009 and 2011 were:
- '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' describes the processes and results of the most comprehensive and accurate survey of the Harbour's seabed.
- 'Patterns and Rates of Sedimentation Within Porirua Harbour' (Available mid November 2009) compares the 2009 bathymetric survey with previous surveys dating back to 1849. Particular analysis of sedimentation changes between the 1974 survey and today.
- '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.
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 invasive 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.
Current research includes the following:
The focus of research for 2011/12 is the development of an understanding of the sources and destination of sediment and contaminants in Porirua Harbour and catchment. The results of this work will be the key element in preparation of a whole-of-catchment re-vegetation plan. A draft is due to be completed by the end of 2012.
An assessment of potential for seagrass restoration by NIWA (which shows excessive sedimentation rates and nutrient levels) will be a key element in developing an estuary restoration plan which is due for completion by the end of 2012.
Ngati Toa Rangatira and NIWA have commenced a fish survey of Porirua Harbour. Interviews and oral recollections by elders of the harbour fishery have been completed.
Greater Wellington and Porirua City Council are partnering in a water quality sampling programme to establish contaminant inputs to Porirua Harbour and streams. Eight months data has already been collected and analysed, and the sampling programme has been refined. The results from this programme will guide priorities for sewer and stormwater infrastructure upgrade and provide a monitoring baseline to guage the impact of these progressive improvements on harbour and stream water quality.
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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Links to more information
Porirua City Council Links
Strategy and Action Plan
Public Seminar Presentations
Please note: some of these files are quite large, and have full colour maps and diagrams.
Silt and Sediment Control on Small Building Sites:
- Seagrass in Porirua Harbour. Preliminary Assessment of Restoration Potential, May 2012 (1.9MB, 35 pages, full colour)
- Coastal Water Quality and Ecology in the Wellington Region (4.1Mb, 101 pages. Full colour)
- Broad-scale Habitat Mapping Report (6.7MB pdf, 41 pages)
- Ecological Restoration Priorities for the Porirua Stream and its Catchment (1.8MB pdf, 62 pages)
- Map - Porirua Stream Restoration Priorities By Sub-catchment (234KB pdf, 1 page)
- Porirua Stream: your stream, your catchment (415KB pdf, 2 pages full colour)
- Best Bets planting guide of restoration plants (1.2MB pdf, 2 pages)
- Land-based effects on coastal fisheries - Ministry of Fisheries report (100 pages)
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For enquiries or more information about the Harbour programme, please contact:
Porirua Harbour Strategy Coordinator
Strategy and Planning
Porirua City Council
PO Box 50-218
Porirua City 5240
Phone: (04) 237 3598
Fax: (04) 237 1445