Addendum Agenda of Waitematā Local Board

Waitematā Local Board

12 May 2015

Waterway Rehabilitation Options In The Waitemata Local Board Area

File No.: CP2015/03808

Purpose

1. To present a report on waterway rehabilitation options in the Waitematā Local Board area to the Waitematā Local Board.

Executive Summary

2. The daylighting of Tunamau Stream in Western Park is one of the Waitematā Local Board’s key advocacy areas. To inform decision making and advocacy, the Waitematā Local Board commissioned the development of a report to investigate options for stream restoration in the local board area, especially daylighting piped streams.

3. Auckland Council’s freshwater biodiversity specialists drafted an options study for consideration by the board at a workshop in late 2014 (Waterway Rehabilitation Options in the Waitematā Local Board Area). This presentation is attached to this report as Attachment A.

4. Previous waterway rehabilitation aspirations focused on daylighting the Tunamau Stream (in Western Park) however this study took a broader approach and investigated ten local parks in the Waitematā Local Board area for their suitability for rehabilitation and naturalization. In no particular order the ten streams investigated were:

o Cox’s Creek Tributary (Hakanoa Reserve)

o Tunamau Stream (Western Park)

o Cox’s Creek Tributary (Grey Lynn Park)

o Edgars Creek

o Point Erin Reserve

o Waipapa Stream (Newmarket, Hobson Bay sub-catchment)

o and four unnamed streams at

o Dove Myer Robinson Park (Parnell)

o Alberon Reserve (Hobson Bay sub-catchment)

o Basque Park, (Motions Creek sub-catchment) and

o Wellpark Reserve (a sub-catchment of Cox’s Creek).

5. Opportunities and constraints for rehabilitation were evaluated for each waterway from stormwater, biodiversity and social perspectives, as detailed in the report.

6. The streams considered to have the greatest daylighting and rehabilitation potential are the Tunamau Stream in Western Park and Edgar’s Creek in Wellpark Reserve. In both cases the potential stream ‘daylighting’ would involve wetland creation as much as stream rehabilitation, because of the stream’s location in the catchment and small potential baseflows.

7. No current funding is available for these daylighting projects however they have been canvassed with local and sports parks and stormwater so that future plans may consider options for rehabilitation where possible.

8. This report presents the options for waterway rehabilitation in the Waitematā Local Board area for the board’s information.

Recommendation

That the Waitematā Local Board:

a) Receives the ‘Waterway Rehabilitation Options in the Waitematā Local Board area’ report.

Comments

Background and Waitematā Local Board aspiration

9. The daylighting of Tunamau Stream in Western Park is one of the Waitematā Local Board’s key advocacy areas. To inform decision making and advocacy, the Waitematā Local Board commissioned the development of a report to investigate options for stream restoration in the local board area, especially daylighting piped streams.

10. Auckland Council’s freshwater biodiversity specialists drafted an options study for consideration by the board at a workshop in late 2014 (Waterway Rehabilitation Options in the Waitematā Local Board Area). This presentation is attached to this report as Attachment A.

11. The scope of the study built on existing aspirations to daylight the Tunamau Stream and a desire to ensure that daylighting the Tunamau was the best and most practicable option especially given the financial implications of this activity. Preference was given to a stream daylighting project should also be:

· A stream daylighting project in preference to a wetland rehabilitation.

· The simplest and least complicated in relation to other matters such as exisiting infrastructure, closed landfills or cross connections and potential wastewater contamination.

Methodology

12. A total of ten streams in local parks were investigated in detail. These were

o Cox’s Creek Tributary (Hakanoa Reserve)

o Tunamau Stream (Western Park)

o Cox’s Creek Tributary (Grey Lynn Park)

o Edgars Creek

o Point Erin Reserve

o Waipapa Stream (Newmarket, Hobson Bay sub catchment)

o and four unnamed streams at

o Dove Myer Robinson Park (Parnell)

o Alberon Reserve (Hobson Bay Sub-catchment)

o Basque Park, (Motions Creek sub-catchment) and

o Wellpark Reserve (a sub-catchment of Cox’s Creek).

13. These streams include those investigated as part of the Mayor’s 100 projects that fell within the Waitematā Local Board area and others were added. The investigation began with a high level GIS assessment of streams in the Waitematā Local Board area focusing on streams traversing local parks and reserves. An assessment was then made on potential biodiversity and stormwater outcomes from daylighting and constraints that would prevent a rehabilitated stream reach from realising its ‘full’ public amenity and biodiversity potential, or that would hinder watercourse rehabilitation works.

14. These streams were visited and staff from the solid waste, stormwater and local parks teams contributed to the identification and assessment of opportunities and constraints in regards waterway rehabilitation.

15. The waterways where stream course rehabilitation, potential community engagement and exposure was rated as high were either currently well visited or there was significant predicted potential for future improved community use. Waterways that were rated as having low potential were often those that ran through small under-utilised suburban parks (compared with other local parks) and where there was little potential for improved community use because of how the pipe was situated within the reserve or reserve topography constraints.

Current State (waterways)

16. Most watercourses in the Waitematā Local Board area extend a short distance inland so are short and drain relatively small catchments. Furthermore, council owned reserves in the Waitematā Local Board area tend to be situatedclose to the streams’ headwaters. Consequently summer base flows in most of the stream reaches of interest are modest, few contain permanent (year-round) flows and in some watercourses there is only scope for seasonal wetland habitat creation.

17. So while the Local Board’s primary interest had been on streams with daylighting potential, a lack of streams with permanent flows meant piped streams also had to be assessed for wetland creation opportunities.

18. Due to cross connections with wastewater systems a number of the streams also receive wastewater overflows, particularly during high rainfall events. Table one summarises the potential of all streams investigated. In this table the potential for watercourse rehabilitation is colour coded for assessment for the respective outcome area with blue meaning advantageous, green meaning neutral and red describing challenging watercourse rehabilitation potential.

Table one: Summary table for ten water courses investigated in the Waitematā Local Board Area

Key blue means advantageous, green means neutral and red challenging watercourse rehabilitation potential.

SUMMARY TABLE
Site	Stormwater			Biodiversity		Community
Cox’s Ck trib (Grey Lynn Pk)	Driver	Priority	Risk	Stream	Wetland	Visibility	Exposure
Cox’s Ck trib (Grey Lynn Pk)	moderate	low	high	low	low	high	mod-high
Cox’s Ck trib (Hakanoa Rsv)	high	moderate	high	moderate	low	low-moderate	low
Edgars Ck (Wellpark Rsv)	low	low	moderate-high*	moderate-high	moderate	high	moderate
Edgars Ck (Cox’s Bay Rsv)	low	low	high	moderate	low-moderate	high	high
Unnamed Stm (Pt Erin Rsv)	low	low	moderate	low	moderate	high	moderate
Unnamed Stm (Dove Myer Robinson Pk)	low	low	low	low	low-moderate	moderate	moderate-high
Tunamau Stm (Western Pk)	high	high	low	low	moderate-high	high	high
Unnamed trib (Alberon Rsv)	low	low	moderate	low	low	low	low
Unnamed trib Motions Ck (Basque Pk)	low	low	high	low	low	low	low
Waipapa Stm (Domain/Pukekawa)	moderate	low	unknown	low	moderate	low	low

Results

19. The investigation found that Wellpark Reserve contained greatest potential to support a stream ecosystem including diadromous fauna (fish that migrate back into freshwater habitat from the ocean) but stormwater drivers were lacking for this waterway.

20. Of those waterways showing greatest potential for wetland rather than stream creation, Western Park (Tunamau Stream) ranked highest. There are also some stormwater and parks drivers, which may be leveraged such as the Western Park i parks renewals and potential stormwater interventions. This study concluded that a wetland in Western Park would enjoy greater exposure and a higher level of public interaction than other local sports parks in the local board area.

Consideration

Local Board views and implications

21. The Waitematā Local Board Plan 2014 describes an outcome of the ‘natural environment is respected and enhanced; our communities help protect and enhance Waitematā’s beautiful natural environments. We are a local carbon community. Specifically the board have identified a kay initiative to ‘identify, restore and partly daylight one stream in Waitematā’.

22. As part of the consultation documentation for the Western Park Development Plan the board has detailed a design principle to maintain and enhance the natural environment including Tunamau (stream) by improving biodiversity in the park through native plantings and rehabilitation of the stream. In this document a desire to incorporate stormwater options to mitigate the flooding risk immediately downstream of Western Park (Freemans Park complex), subject to finalised stormwater modelling, is also detailed.

23. The Waitematā Local Board has demonstrated strong advocacy for daylighting and rehabilitating waterways within the Waitematā local board area.

24. As part of the Western Park Development Plan options for rehabilitation of the Tunamau Stream that runs through the park are noted as under investigation alongside some potential stormwater interventions and biodiversity improvements including a potential wetland.

25. This report was workshopped with the Waitematā Local Board in late 2014.

Māori impact statement

26. While this report is for information only and does not require any decision making, it is recognised that environmental management, water quality and land management has integral links with the mauri of the environments and concepts of kaitiakitanga.

27. Work to progress waterway rehabilitation options within the Waitematā Local Board area should be enacted partnership with iwi to express iwi values associated with the respective waterways through the application of Te Aranga Māori Design Principles.

Implementation

28. This is a report providing subject matter expert advice on potential options for waterways rehabilitation within the Waitematā Local Board area. It has not identified the potential cost of rehabilitation options nor funding options.

29. No current funding is available for these daylighting projects however they have been canvassed with local and sports parks and stormwater so that future plans may consider options for rehabilitation where possible.

Attachments