|
|
|
|
|
Item not on the Agenda |
||
|
Report To: |
Tauranga Moana Advisory Group |
|
|
Meeting Date: |
8 September 2023 |
|
|
Report Writer: |
Jackson Efford, Principal Advisor, Land and Water |
|
|
Report Authoriser: |
Chris Ingle, General Manager, Integrated Catchments |
|
|
Purpose: |
To update Members on the Land Management work programme around Tauranga Moana |
|
Tauranga Moana Land Management Operations Update
|
Executive Summary This report was originally presented to the BOPRC Monitoring & Operations Committee meeting on 7 March 2023. This is a summary of Land Management operations within the Tauranga Moana Freshwater Management Unit area. It includes an update on progress within the harbour’s Focus Catchments of Waitao (Kaiate Falls), Kopurererua, Te Mania and Uretara, as well as providing other operational highlights over the past 12 months. Preliminary summer water quality results are available for Kaiate Falls, suggesting that the targeted Focus Catchment work is having a positive outcome on helping to reduce E. coli levels at this high profile swimming area. Similar Land Management updates will follow at subsequent Monitoring and Operations Committee meetings, including for Kaituna/Maketū Estuary, Waihī Estuary, and the eastern Bay of Plenty Focus Catchments, along with separate updates on the Biodiversity and Coast Care programmes. |
That the Tauranga Moana Advisory Group:
1 Receives the report, Tauranga Moana Land Management Operations Update and accepts it as an Item not on the Agenda.
2 Notes the reason why this item was not on the Agenda is that the report was not yet ready, and the reason why it cannot be delayed is to ensure the information is still provided in a timely manner.
The Western Land Management team delivers a diverse range of operational works around Tauranga Moana to improve water quality and biodiversity, including the ‘Focus Catchments Programme’ which aligns our work with the highest Essential Freshwater programme priorities such as improving the swimmability of poorly performing swimming sites. Previous Tauranga Moana Advisory Group reports provide programme background and updates. This report provides an update on the targeted work which continues in the priority Tauranga Moana Focus Catchments of Waitao, Kopurererua, Te Mania, and Uretara.
We are now several years into the programme and some of the smaller Focus Catchments have experienced a slight decline in the rate of new land management works able to be achieved voluntarily, using education/incentive-based approaches with willing landowners - notwithstanding that a significant amount of work has been successfully achieved with community in these areas to date. Additional Focus Catchment support is now being extended to other priority areas within the harbour, including the Wairoa Catchment and “Project Parore’s” northern Tauranga harbour catchment group area. This work aligns closely with the Council’s Essential Freshwater programme priorities for the Tauranga Moana Freshwater Management Unit where a moderate (10-40%) level of change is likely required to both sediment and E. coli, meaning our land management activity and interventions are an important delivery tool for achieving water-quality improvements.
1.1 Legislative Framework
The Land Management programme is an education and incentives-based work programme. It both compliments and aligns with the legislative requirements and priorities of the Essential Freshwater Programme for Bay of Plenty, as well as other priorities such as biodiversity and care group support.
1.2 Alignment with Strategic Framework
|
A Healthy Environment |
We work cohesively with volunteers and others, to sustainably manage and improve our natural resources. |
|
Freshwater for Life |
We deliver solutions to local problems to improve water quality and manage quantity. |
The Land Management programme aligns with a number of community outcomes, including those related to Healthy Environments and Freshwater for Life. Our Focus Catchments work is monitored in a number of different ways, including the Council’s ‘Swimmability’ KPI and through the Councils wider water quality monitoring programmes. Ultimately, the Focus Catchment Programme becomes a key link between voluntary land management action and the Council’s requirements to deliver the NPS-FM.
1.2.1 Community Well-beings Assessment
|
Dominant Well-Beings Affected |
|||
|
þ Environmental High - Positive |
þ Cultural Medium - Positive |
þ Social Medium - Positive |
þ Economic Low - Positive |
Focus Catchments work contributes directly to positive environmental outcomes as its core purpose, with positive co-benefits around Cultural and Social well-beings
2.1 Focus Catchments update
Work continues to be delivered throughout the Kopurererua, Waitao, Uretara and Te Mania sub-catchments of Tauranga Moana as part of the Focus Catchments programme, along with other priority community projects around the rest of the harbour. The following provides some highlights of completed and planned activities in each catchment, including monitoring from Kaiate Falls. Overall, Tauranga Moana Land Management activity is significant with over 100 active Environmental Programmes, 80 km of protection fencing, and over 1 million native plants established in recent years.
2.2 Kopurererua Catchment Summary
The Kopurererua catchment is 7,400ha in size and located to the Southwest of Tauranga City, it flows north from the Mamaku Plateau foothills approximately 450 m above sea level, through the western suburbs of Tauranga City and discharges into the Waikareao Estuary in Tauranga Harbour. The total length of streams in the catchment is approximately 150 km with the Kopurererua approximately 29 km long. The catchment has two main tributaries, the Tautau and the Nanakau. The Tautau is the largest tributary at 18 km long and is one of the two spring fed awa supplying water for Tauranga City. The catchment receives 1968 mm of rainfall on average per year.
The catchment is dominated by three distinct geographical zones. The lower catchment is dominated by the low-lying Kopurererua Valley Reserve floodplain and wetlands, bordered by low-lying hills <100m asl. Urban and industrial development in this area has led to increased stormwater runoff due to a reduction in permeable areas. The mid catchment sees a significant gradient change from the upper catchment and is characterised by meandering streams and wide alluvial valleys bordered by steep hills and flat plateaus. The soil types and geology make this area vulnerable to stream bank erosion and soil loss, especially where intensive land use change has occurred.
The upper most part of the catchment (above Taumata Road) on the Mamaku plateau foothills is characterised by steep to rolling sheep and beef hill country, with a large network of ephemeral flow paths that contribute high amounts of sediment and nutrients into the Kopurererua and Tautau streams during high intensity rainfall events. There are no perennial waterways in this part of the catchment.
Current landuse in the Kopurererua catchment.
The Kopurererua Catchment has an on-going sediment and Escherichia coli (E.Coli) issue which impacts in-stream values and the downstream receiving environment of Waikareao Estuary. The bathing site (Canoe Slalom gates) at McCord Avenue in the lower Kopurererua stream frequently exceeds safe levels for contact recreation.
The last 18 months have seen targeted approach with landowners, hapu, and community groups throughout the catchment to develop Environmental Programmes that seek to improve land management practices and water quality outcomes in the catchment. This includes (completed and planned works) 7 km of new stock exclusion fencing, 14 ha of land retirement, 2 detainment bunds, and over 290,000 native plants in the ground (this includes planting as part of the Kopurererua re-alignment project). In total, 100ha of land has been retired in the catchment under existing and historical BOPRC programmes.
2.2.1 Kopurererua Environmental Programmes
There are currently 11 active environmental programmes within the Kopurererua Focus Catchment.
1. Given our current understanding of water quality and contaminant sources in the catchment, the upper catchment environmental programmes are targeted towards sediment reduction activities such as retirement/planting of steep erosion prone land, coupled with construction of detainment bunds to attenuate sediment and phosphorus that is usually transported during high intensity rainfall events.
2.
3. However, recent water quality monitoring also indicates elevated nitrogen concentrations at Taumata Road bridge that is likely anthropogenic in nature. Working with landowners in the upper catchment to undertake detailed farm planning and systems analysis along with an improvement in some intensive winter grazing practices will be a focus moving forward.
4.
5. Environmental programmes in the mid catchment are focussed on good management practice in riparian zones, particularly as the gradient and geology in this area make it prone to stream bank erosion. The mid catchment is also home to many floodplain and hanging wetlands that hold good enhancement potential. A recent survey identified 33 natural wetlands in the mid-catchment that were predominantly palustrine marsh/sedgeland (Morphum, 2021). The vegetation condition of these wetlands varies, with a number having grey willow infestations. There are 3 environmental programmes in the mid-catchment that have a focus on willow control and native revegetation in these wetlands.
An example of riparian retirement and planting in the mid Kopurererua catchment.
The lower catchment has one environmental programme in partnership with Tauranga City Council (TCC) and Ngāi Tamarawaho. Motuopae Island is an Urupa for Ngā Tamarawaho hapū and their ancestors. It is a BOPRC priority biodiversity site, and this environmental programme has a focus on pest control and re-vegetation with a large amount of in-kind contribution and volunteer hours being undertaken by the hapū.
2.2.2 Kopurererua Detainment bunds
The large network of ephemeral flow paths in the upper catchment contributes increased amounts of surface runoff into the Kopurererua and Tautau streams during high intensity rainfall events. This surface runoff is often laden with sediment and nutrients which negatively impacts water quality and ecological values. This part of the catchment is well suited to the construction of detainment bunds due to its favourable contour, network of ephemeral flow paths, and propensity for high intensity rainfall events.
A detainment bund is a low earth berm placed across and ephemeral flow path and is designed to temporarily detain stormwater run-off to improve water quality outcomes, the ponding duration is temporary (up to 72 hrs to ensure no compromise in pasture) with an upstand riser and plug allowing for sediment and nutrients contained in the ponded water to settle out into pasture during this time. Detainment bunds are generally located on valuable and productive pasture, as these gentle contour areas generally make suitable ponding areas. They form a seamless integration into the landscape that do not require large areas of to land to be retired to improve water quality outcomes. Several detainment bunds have been constructed in the Lake Rotorua catchment to assist with improving water quality outcomes, and recent PhD research completed on these structures indicates that detainment bunds retain 47-68% of phosphorus and 51-59% of suspended sediment (Levine, 2020).
The sequence of detainment bund ponding and releasing during a storm event.
Early 2022 saw the construction of the first detainment bund for the upper Kopurererua catchment. This site is intended to be used as a demonstration site to promote wider uptake in the Tauranga Harbour Catchment. The design and construction for a second detainment bund on a neighbouring property is planned for completion in 2023.
There has been some recent work completed in the mid and upper catchment to scope further suitable sites for detainment bunds that meet optimum storage ratios under BOPRC Detainment Bund Guidelines. This study indicated that there are approximately 36 feasible sites in the upper catchment, and 11 in the mid catchment. Staff will be working with landowners of these identified sites in the coming 12 months to gauge interest in any further construction of detainment bunds.
The recent weather event in late January 2023 saw this detainment bund ponding and working as designed.
2.2.3 Koromiko wetland fish habitat project (Kopurererua)
BOPRC are partnering with TCC and Ngāi Tamarawaho, along with funding partners, Ngā Matarae Trust/Port of Tauranga to enhance fish passage and habitat in the Koromiko wetland in Judea.
The flood impact modelling and concept design has now been completed. The project steering group will convene in early March to approve one of three concept design options, before progression to detailed design and construction in late 2023.
2.2.4 Kopurererua re-alignment
Restoration of the Kopurererua Valley has been planned and undertaken at various times over the past 15 years. Historically the lower reaches of the Kopurererua stream have been straightened, cleared and drained for pastoral farming. These activities have negatively impacted on water quality and habitat in the area as well as reducing the flood capacity in the catchment. The re-alignment project is a partnership between TCC, BOPRC and Ngāi Tamarawaho and is split in to two parts, Northern and Southern. The purpose of the project is to restore the Kopurererua stream to a more natural path which will increase in-stream habitat, reduce velocities, increase sediment deposition (via submerged benches and sedimentation wetlands) and allow for floodplain engagement during high flows. Several logs and in-stream woody features will be placed in the channels and will assist with creating diversity and habitat for native fish, along with two new bridges and associated pathways to enhance accessibility for pedestrians and cyclists. The existing channels are to be de-fished and backfilled to surrounding ground level upon completion of the re-alignment.
The proposed alignment has been selected based on matching the historic sinuosity and alignment (where possible) and avoidance of site constraints, including the Nanako Stream confluence, topographical features, gas and power/transmission lines and cycleway and access roads. The proposed alignment also retains existing maintenance access for utility owners.
The re-alignment project commenced in January 2022 and is due for completion in 2024. A total of 270,000 native plants will be planted over the course of the project. The project and all procurement is being led by TCC with support from Ngāi Tamarawaho and BOPRC. The total project value is over $4,000,000 with $1,268,000 in funding from BOPRC.
Southern re-alignment
Earthworks for the southern part of the re-alignment are nearing completion. The excavation of the new channel was completed in April 2022 with the banks and submerged bench planted in winter 2022 (38,832 plants). Construction of the sedimentation wetland is well underway and due to be completed in March 2023. A further 187,736 plants are due to be planted in the floodplain and sedimentation wetland in winter 2023.
The new channel is currently blocked by an up-stream and down-steam ‘plug’, the excavation of these plugs and the subsequent de-fishing and backfilling of the existing channel is planned to occur in mid-February (weather permitting). Upon completion of this, the new southern re-alignment will be ‘live’.
Southern re-alignment detailed design.
The new southern re-alignment channel.
Northern re-alignment progress
The excavation of northern re-alignment channel was completed in December 2022. In-stream features such a log groyne, and v-log weirs are planned to be installed in March/April 2023, prior to the close of earthworks season. Winter 2023 will see 31,720 native plants planted along the banks of the new channel. The ‘livening’ of the northern re-alignment channel, including the excavation of the upstream and downstream plugs will occur in the summer of 2024. A small amount of in-fill planting will be completed in 2024.
Northern re-alignment detailed design.
2.2.5 Fish passage remediation in the Nanakau Stream (Kopurererua)
As part of a catchment wide waterway assessment for the Kopurererua in 2021, several in-stream structures were assessed for their capacity to enable effective fish passage. A total of 54 structures were identified as posing a barrier to fish, with 77% being artificial such as perched culverts or pipes. A large portion of these barriers are in the Nanakau tributary in the lower urban catchment, and are located on a mix of public and private property. A local specialist has been engaged to undertake small scale remediations to those identified barriers throughout the Nanakau Stream tributary. The fieldwork and reporting for this project is nearing completion.
This structure has had 450mm flexi-baffles installed to create complex flow allowing for rest pools and increased depth of water, reducing energy demand for migrating species.
2.2.6 Priority Kopurererua actions for 2023/2024
1. Utilising the detainment bund scoping work for the mid and upper catchment, including engagement with landowners that have suitable sites and progress through to design and construction where appropriate.
2. In collaboration with industry, work with individual landowners above Taumata Road to identify critical source areas, intensive winter grazing, and opportunities improve to farm system practices.
3. BOPRC to continue an active role in supporting the development and construction of the Kopurererua re-alignment to enhance biodiversity and increase sediment deposition.
4. Continue to work with individual landowners to develop Environmental Programmes that contribute to enhanced biodiversity and water quality outcomes in the catchment.
1.
2.3 Waitao (including Kaiate Falls) Focus Catchment
Engagement with landowners in the wider Waitao catchment is continuing in accordance with our internal prioritisation list. A number of projects are either planned or underway. Recent weather events have caused significant damage throughout the catchment, including damaged fences, slips, stream bank erosion and stream blockages Planning is underway to support and rectify damage where possible.
Summer water quality monitoring in the sub-catchment at and above Kaiate Falls is well underway, and the results appear to show reduced E.coli levels compared to usual, which is very encouraging and indicates the likely effectiveness of this highly targeted work to address water quality (as seen in Table 1 below).
Scientific and statistical analysis will be completed once all summer monitoring has been completed later in March, and consider factors such as waterway flow data, land management change and rainfall.
Summer
water quality monitoring this summer vs last summer at Kaiate Falls below,
showing that the E. coli situation appears to have improved following land
management interventions 
.
 |
Kaiate Falls Catchment looking up two of the gullies toward the Ōtawa trig carpark during planting 2020. Note the amount of water sitting in the wetland/gully area
Similar photo point as above taken spring 2021 post releasing, natives establishing well.
Different angle, same plantings in summer 2023. Very few losses have been identified and plants are thriving.
2.4 Uretara Focus Catchment
There are currently five active Environmental Programmes in the Uretara catchment at various stages in their five-year programmes. One of these is newly signed this year. Three are principally wetland restoration projects, one extensive steep land and riparian retirement and the other riparian retirement.
The relationship with Project Parore continues to strengthen with active partnership both financially and in terms of implementation. Their works crew has been integral with planting and pest plant activities in many of the programmes. Significant work is underway around planning new collaborative projects with private landowners and the three northern hapū of Tauranga Moana.
The following is a summary of some highlights from the past year.
Lindemann Road EP – this property is a 51 hectare, steep dry stock property adjacent the Kaimai Forest Park. Over the past 12 months approximately 4km of fencing has been constructed to protect a total of 28ha (21.5ha native forest and 6.5ha of steep gullies and watercourses). Major pest plant control has been undertaken in preparation for the planting of 16,000 native plants this coming winter in the steep gullies.
Lindemann Rd Property looking along fence line that removes stock from 22ha of native forest contiguous with the Kaimai Forest Park
Lindemann Rd property looking down on one of two large steep gullies. They are newly fenced and note the extensive dead gorse and privet done in preparation for planting winter 2023.
Henry Road Wetland – on this property a previously drained wetland was reinstated by blocking up the drain. The wetland and margins were fenced and planted. This wetland provides biodiversity habitat and filters surface and ground water from a contributing catchment of intensive grazing land.
Uretara Dairy Farm – this farm is the single largest farming enterprise in the Uretara catchment. This dairy property has recently changed hands and Regional Council is working with the owner and Tipu Whenua consultants on a farm planning exercise to look at the risks and opportunities for environmental retirement and mitigation works.
Inanga spawning habitat – the development of a new EP to restore inanga spawning habitat along the tidal reaches of the Uretara River is currently in progress. This is collaborative project between Western Bay of Plenty District Council, Ngāi Tamawhariua, Project Parore & Regional Council. It is expected that any physical works will be undertaken next spring after the upcoming spawning period but pest plant control and planting will commence shortly.
Uretara Riverbank below SH2. Photo taken the hightide the day before cyclone Gabrielle so the visible water level is slightly higher than typical spring tides. The flooded portions of the riverbank will be enhanced as spawning sites for inanga by shallow excavations and extensive planting.
Upper Busby Rd community – in collaboration with Project Parore we are currently exploring a landscape scale biodiversity restoration and management plan with the community. At the top of Busby Rd there is a community of approximately 15 lifestyle blocks adjacent the Kaimai Forest Park. The landscape is extremely steep with ecologically significant remnants of scattered forest. Many in the community are keen to instigate a network of pest animal control and create corridors of native forest linking the remnants. Individually the properties are relatively small but collectively significant.
2.5 Te Mania Focus Catchment
There are currently 11 active Environmental Programmes at various stages in the Te Mania catchment. Most of these are in the maintenance stages with the exception of 3500 native plants planted last winter, the last of a 5 hectare steep land retirement programme.
A considerable amount of works has been completed over the past four years. The maintenance phase is a crucial one in the relative success of any retirement project. Pest plant control is the main activity to allow native plantings to thrive.
There are two newly signed programmes this year which will see 3.5 ha of steep land retired later this summer and 9,500 native plants planted this coming winter.
2.6 Care Group Programme celebration events
A series of events were held solely for volunteers in the months of October/ November 2022 as a thankyou for all the wonderful work our volunteers do across the BOP rohe. These events were hosted by the “Flaxroots Forum” which is a collective of organisations and agencies who support environmental groups (Bay of Plenty Regional Council, Tauranga City Council, Western Bay of Plenty District Council, Bay Conservation Alliance, Envirohub and the Department of Conservation).
Each event would provide a chance for our volunteers to network amongst each other, showcase their own work, share ideas and learn from one another. Four Open days were selected. Johnson Reserve (an urban pest plant control focussed care group – TCC), Friends of the Blade (a pest animal control group in the Kamai Mamaku Forest- DOC), Western Bay Wildlife Trust (a species focussed group in an urban area – TCC & DOC) and MOWS (a group with a wide range of activities working in a coastal and wetland environment- WBOPDC & DOC).
BOPRC also designed certificates that were signed by the Flax Roots group. These were then framed & presented to the host group with a $200 grocery voucher as Koha.
Each of the Events were completely different from small to larger gatherings. All volunteers mingled and morning tea networking was successful. A wide range of Volunteer groups were represented throughout the Western region with a range of age groups and demographics. Some very positive feedback was received, with groups arranging amongst themselves to visit other volunteer groups and the comment made “that if this event takes place next year, we would be strongly encouraging more members to come along”.
2.7 Mangrove management
2.7.1 Seedling control work
There are 9 active estuary care groups in Tauranga Moana area involved with mangrove seedling works. Volunteers in groups continue to remove seedlings annually in feasible areas within their rohe through working bees and lone work. Volunteers have cleared/kept clear around 238ha between 1 Jan 2022 and 1 Jan 2023.
BOPRC Contractors are utilised for seedling control in areas that are higher-risk to volunteers (deeper sediment) or where groups are not active. Contractors cleared 75ha between 1 Jan 2022 to 1 Jan 2023 costing around $88,650.00. Petrol or electric scrub bars are the preferred tool.
2.8 Sea Lettuce Clean-Ups
In previous years the regional council and Tauranga City Council (TCC) have invested in beach-cast sea lettuce clean-ups around popular public areas such as Kulim Park in Matua, keeping these areas free of nuisance lettuce for recreation activities. This work is completed together with TCC under a Memorandum of Understanding where we fund 50% of costs. In previous years the tonnage of sea lettuce collected has ranged around 200-1,000 tonnes, but no collections have been required this year.
Sea lettuce growth dynamics can be cyclic, but the lack of sea lettuce this year could be attributed to the La Nina weather pattern and unusually warm water temperatures (temperatures above the optimum for sea lettuce growth). Previous sea lettuce blooms are often associated with El Nino weather patterns. Our Land Management works to address sediment and nutrient run-off into Tauranga Moana may also help to reduce the occurrence of sea lettuce blooms.
2.
Considerations
3.1 Risks and Mitigations
There are no significant risks to this work programme at this time.
3.2 Climate Change
|
Mitigation |
Adaptation |
|||
|
Reduce GHG emissions |
Produce GHG emissions |
Sequester carbon |
Anticipate climate change impacts |
Respond to climate change impacts |
|
☐ |
☐ |
☒ |
☐ |
☐ |
Planting and land retirement activities can help to sequester carbon and produce buffers for climate change.
3.3 Implications for Māori
Catchment work spans the rohe of a number of different iwi/hapū. Consideration has been given to the aspirations of iwi/hapu in the work programmes of each focus catchment, with strengthening partnerships in various stages of engagement and development.
4.1 Community Engagement
|
3.
|
INVOLVE Whakaura |
To work directly with affected communities throughout the process to ensure that their issues and concerns are consistently understood and fully considered in Council’s decision making. |
The Focus Catchment Programme approach relies strongly on collaborative, voluntary work with landowners and community to achieve water quality objectives
4.2 Financial Implications
This work fits within the allocated budget for the programme. Demand remains high for incentivised land management work and new Government funding such as the Hill Country Erosion Fund will continue to increase the scale and quality of on-the-ground actions possible.
Next Steps
The Land Management team will continue to deliver its work programme across Tauranga Moana with community. Re-prioritisation of Focus Catchments will occur as further Essential Freshwater Policy Programme priorities become available and water quality data is received.