Porirua Harbour and Catchment Management Programme
This page describes the Porirua Harbour and Catchment Management Programme, with reports, links and video showing a Day in the Life of Porirua Harbour which includes Pauatahanui Inlet and Onepoto Arm.
Have Your Say
Preparation has begun of a strategic plan for Porirua Harbour. The joint Councils heading the project want to hear from the public about specific actions they want considered as part of that plan.
In mid June, a public information and discussion brochure on Porirua Harbour was jointly released by the three Councils covering the Porirua Harbour catchment - Porirua City Council, Wellington City Council and Greater Wellington Regional Council - seeking community feedback on specific ways to improve the condition and enjoyment of Porirua Harbour. This feedback will be considered alongside the Council, central government and other agencies coordinated work to prepare a holistic plan for restoring and maintaining the health of the harbour. The draft strategy and action plan will be released by mid 2011 for public submissions.
The attractively presented discussion brochure outlines the significance of Porirua Harbour, general information received from the community so far, key points from harbour research, and the broad focus of the joint work by the three Councils and other agencies.
Your feedback on specific actions that you would like considered as part of the strategy development ,can be sent to:
Keith Calder
Porirua Harbour Strategy Coordinator
Porirua City Council
PO Box 50218
PORIRUA 5240
Email: kcalder@pcc.govt.nz
Closing date for feedback is 20 August 2010.
A Day in the Life of Porirua Harbour
View 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.
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 is also developing or 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)
-
City Centre Revitalisation
-
Porirua Development Framework
-
Harbour walkway development
-
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)
< back to table of contents >
Porirua Harbour and Catchment Literature Review
Later today (Monday 22 March 2010) online access will be available to two new 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.
< back to table of contents >
Southern Okowai Lagoon to become freshwater wetland
Work commenced Monday 22 March 2010 on Porirua City Council's southern Okowai Lagoon to create a freshwater wetland that will restore the lagoon’s appearance and improve water quality and habitat for its freshwater species.
The small northern and southern lagoons are situated below Gear Homestead on Okowai Road.
The work, paid for by Aotea developers Carrus Ltd, involves contouring the edges of the lagoon and creating a longer and flatter weir between the two lagoons.
This will provide a passage for fish and a better ecological connection between the two lagoons. Riparian and wetland planting will also be done to provide appropriate native wetland plant species habitat.
The contouring work is expected to take two weeks and make use of the current low water levels in the lagoons.
The lagoons have suffered from a range of visual, water quality, and odour problems since they were created when the causeway for the railway line (and subsequent State highway) was built. The problems are a consequence of insufficient tidal flushing of the lagoons combined with ongoing land clearance and earthworks within the catchments discharging into them.
This work is the most recent example of a growing number of multi-agency initiatives to improve wildlife habitat and the quality of water entering Porirua Harbour. Porirua City Council, Greater Wellington Regional Council, and the Department of Conservation have worked with Aotea Block developer, Carrus Ltd, to consider options to clean up recurring silt problems in the lagoon and restore a wetland habitat. Carrus engaged an ecological advisor to write a remediation plan and have improved sediment control, added wetland areas and are now paying for this remediation work. Some minor initial works have also been undertaken on the northern lagoon to enhance its environmental values
< back to table of contents >
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 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.
These reports highlight a number of critical aspects about the biophysical condition of the Harbour and catchment:
- moderate levels of heavy metal contamination in areas of the Onepoto Arm and concerning levels of DDT in both arms of the Harbour.
- confirmation of significant sediment accumulation, particularly in Pauatahanui Inlet
- algal growth is a good indicator of nutrient enrichment problems for the Harbour
- significant opportunities to improve stream quality
- 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 current research for 2010 is the funding and development of a hydrodynamic model for Porirua Harbour and catchment. The three staKeholding councils (Porirua City, Wellington City and Greater Wellington) have partnered with New Zealand Transport Agency and Transmission Gully Motorway Project to undertake the modelling and each use the model for their respective analysis. Field work for the model began before Christmas and it is hoped to have final results from the model before the end of this year. These will then help direct elements of the final strtaegy document and action plan.
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.
< back to table of contents >
Future Focus
Programme focus over the first half of 2010 will be to complete preparation of and release a public Discussion Document in late March for the harbour and catchment strategy. The document will seek broad public input on values, issues and expectations related to the harbour and catchment. Responses from the public, businesses, organisation and agencies will be used to shape the eventual strategy document. The document will be publicly advertised and obtainable in hard copy or downloadable from this webpage.
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
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
< back to table of contents >