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.
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 are now available online, and hard copies available at council offices and libraries. A mailing list of local and regional interest groups have been 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:
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Partnership – forming partnerships with key agencies and organisations – 2008-10
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Research – a targeted research and monitoring programme - 2008-10
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Planning – public Strategy development and preparation process – 2008-11
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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:
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Review of strategic infrastructure assets (stormwater, sewerage, water reticulation and landfill)
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Storm Water Action Plan
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City Centre Revitalisation
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Porirua Development Framework
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Harbour walkway development
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Trade waste bylaws
Aerial photo
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.
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
- 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.
The reports are available to view from the links below.
The focus of research for 2011 is the development of an understanding of the sources and destination of sediment and contaminants in Porirua Harbour and catchment. In partnership with the New Zealand Transport Agency and the Transmission Gully Motorway Project, the three staKeholding councils (Porirua City, Wellington City and Greater Wellington) have prepared a computer-based hydrodynamic model of the harbour. Tidal flow and sediment transport models have been produced and these will be used to assist sediment and contaminant analysis. These will then help to refine elements of the final strategy document and action plan due for release mid 2011.
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
Public Seminar Series Presentations
Please note: some of these files are quite large, and have full colour maps and diagrams.
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
Strategy and Planning
Porirua City Council
PO Box 50-218
Porirua City 5240
Phone: (04) 237 3598
Fax: (04) 237 1445
Email:
kcalder@pcc.govt.nz