The projects below show our catchment work in practice, at scales from a single small lake catchment to a national map series spanning eight regions and 3.7 million hectares, and in settings from lowland drainage districts and a foothill valley to a city’s largely piped urban streams. Across all of them the task is the same: draw together information from many sources into a clear picture of how a catchment works, and a practical, co-designed plan for acting on it. It’s work built to be carried forward by the councils, rūnanga, landowners and community groups who live and work in these catchments.
Ararira/LII Catchment Management Plan & Implementation Guide
A co-designed catchment plan for the Ararira/LII drainage district that fundamentally rethinks a lowland drainage network as an ecological and cultural system – the pilot that proved the Selwyn District catchment-planning model.
In October 2020 the DOC–Fonterra Living Water Partnership signed a Memorandum of Understanding with Selwyn District Council and Te Taumutu Rūnanga to develop a Catchment Management Plan (CMP) and Implementation Guide (IG) for the Ararira/LII River drainage district – the second largest contributor of water to Te Waihora/Lake Ellesmere, one of the most degraded coastal lakes in Aotearoa. EOS Ecology, working alongside Aqualinc Research (programme management and hydrology) and Cawthron Institute, was engaged to deliver the work in close co-design with the full Project Team – SDC, the LII Drainage Committee, Te Taumutu Rūnanga, Living Water (DOC and Fonterra), Environment Canterbury and Learning for Sustainability. The MOU set the bar high: “fundamentally change the way waterways were valued and managed by incorporating ecological and cultural principles into the design while also recognising that drainage would remain a key value”.
EOS Ecology led the development of the CMP itself – characterising the current ecological state and pressures, surfacing the catchment’s core challenges (excessive fine sediment, abundant macrophytes, lack of space for channel improvements, and farmland flooding), and developing the response in genuine co-design with the Project Team. Our GIS team built a new spatial framework using LiDAR-derived digital elevation models – interrogating twenty existing GIS layers and ground-truthing the network through field surveys assessing flow permanence, channel condition, eDNA and macroinvertebrate samples – to replace the existing layers that significantly under-represented the actual extent of the drainage network. The plan paired catchment-scale approaches with a ‘toolbox’ of reach-scale interventions, customised for the catchment’s ephemeral, intermittent and perennial waterway types. Sitting alongside the technical content was a deliberate science-communication and graphic-design effort that turned the analysis into a highly visual document for public dissemination, together with a ‘blueprint for change’ diagram capturing the key steps in the process.
The CMP was presented to SDC Councillors in August 2022 and met with strong support; the final CMP, Implementation Guide and a 27-page Summary were handed over to Selwyn District Council in June 2023 and published on the Living Water website. As a ‘blueprint for change’, the plan positions SDC to be ‘plan-ready’ for improving the health and mauri of Te Waihora and the Ararira/LII catchment, and is directly applicable to other drainage districts within the Te Waihora catchment and other lowland regions of Aotearoa. The pilot proved the model: SDC subsequently commissioned EOS Ecology and Aqualinc Research to apply the same approach across the six remaining rated catchments in the district (Osbornes Drain, Greenpark, Leeston, Ellesmere, Taumutu and Wairiri Valley), with the Ararira/LII work now cited as a reference example within the wider Living Water programme.
Osbornes Drain Catchment Management Plan
The second CMP in the Selwyn District programme after the Ararira/LII pilot – built around a defining technical reality unique to Osbornes: every drop of water leaves this 1,780 ha catchment via a pump station discharging to Te Waihora/Lake Ellesmere.
Osbornes Drain catchment is a 1,780 ha rural drainage scheme on the western shore of Te Waihora/Lake Ellesmere – entirely flat, dominated by poorly drained gley soils, salt-enriched from its former life as a shallow brackish bay of the lake, and underlain by a continuous aquitard that gives it no recorded springs and minimal deep-groundwater input. What makes Osbornes ecologically and operationally distinctive is its outlet: every drop of water leaves the catchment via a pump station, draining over a Halswell Canal embankment that has stood since 1889. EOS Ecology and Aqualinc Research were commissioned by Selwyn District Council to develop the catchment’s first full Catchment Management Plan (AQU02-23079-01, March 2026) – the second plan in the SDC programme after the Ararira/LII pilot, required under conditions 23–26 of SDC’s discharge consent (CRC172231, which expires 24 February 2027). The plan was co-designed with the Osbornes Drain Catchment Management Working Party – Te Taumutu Rūnanga, Te Rūnanga o Ngāi Tahu, the Department of Conservation, the Osbornes Land Drainage Committee, Canterbury Regional Council and SDC – and sits within the wider Whakaora Te Waihora Co-Governance Agreement signed in 2012.
Authored by EOS Ecology with Aqualinc Research, the plan draws on eDNA and conventional kick-net macroinvertebrate sampling, electrofishing and historic fish records, a five-year synthesis of SDC’s monthly water-quality monitoring (alongside ECan’s earlier intensive dissolved-oxygen dataset), and a new LiDAR-derived waterway layer built and ground-truthed by EOS Ecology’s GIS team that lifted the mapped drainage network from ~48 km to ~95 km – plus a further ~75.5 km of informal overland flow paths that had never previously been captured. The ecological picture is sobering: all macroinvertebrate sites were in ‘Poor’ condition (MCI 37–52); eleven fish species were recorded across the catchment (eight upstream of the pump), including threatened īnanga (Nationally Vulnerable), longfin eel and common smelt (At Risk – Declining) and upland bully (At Risk – Naturally Uncommon); and dissolved reactive phosphorus, E. coli and dissolved oxygen consistently fail the discharge consent’s water-quality conditions, with a worsening DO trend recorded from 2014 to 2021.
The CMP responds with four catchment-scale approaches – transformative practice through Farm Environment Plans and Stormwater, Drainage & Watercourse Management Plans under the new SDC Bylaw 2025; strategic land-use change; smart drainage monitoring systems; and a phased shift away from whole-channel mechanical clearance toward focused sediment-trap maintenance – and a 20-tool reach-scale ‘toolbox’ built specifically around the pump-discharge reality. Several of the Osbornes tools weren’t in the Ararira pilot: fish-friendly pump options (Archimedes screw, axial-flow, submersible) with longer-term consideration of pump-station removal, floating wetlands, aeration pumps, low-flow discharge to land, a large-scale two-stage channel on the mainstem, an inline event-based sediment trap with water-level control, and bunded sediment stockpiles. SDC undertook a comprehensive sediment-removal programme in November 2024 to set baselines, and implementation will be staged through the 2026/27 Annual Plan and the 2027–2037 Long Term Plan. Underpinning the whole plan is the whakataukī “Mā pango, mā whero; ka oti te mahi” – by red and by black, the work will be completed.
Wairiri Valley Catchment Management Plan
The third CMP in the Selwyn District programme – a foothill, gravity-fed scheme where the central challenge is sediment from a much larger surrounding hill catchment, and a downstream willow choke that floods the rated land six or seven times a year.
The Wairiri Valley Land Drainage Scheme sits where the Canterbury Plains meet the Southern Alps foothills, around 300 m above sea level west of Glentunnel and Whitecliffs – beyond the inland extent of the Canterbury Plains aquifer system, draining via Wairiri Stream as an upper-plains tributary of the Waikirikiri/Selwyn River about 60 km upstream of Te Waihora/Lake Ellesmere. EOS Ecology and Aqualinc Research were commissioned by Selwyn District Council to develop the catchment’s first Catchment Management Plan (AQU02-22072-01, draft for SDC sign-off May 2026) – the third in the SDC programme after the Ararira/LII pilot and Osbornes Drain. Unlike its lowland predecessors, Wairiri Valley is foothill country: a 377 ha rated scheme of gley-soil valley floor embedded in a 2,757 ha wider catchment of pallic and loess hills, with a working party – Te Komiti Waiora – that brings together Te Taumutu Rūnanga, Te Ngāi Tūāhuriri Rūnanga, Te Rūnanga o Ngāi Tahu, the Wairiri Valley District Committee chair, the Department of Conservation, Canterbury Regional Council, Fish & Game and SDC.
Authored by EOS Ecology with Aqualinc Research, the plan diagnoses a very different problem from the lowland schemes. Drainage is needed primarily because of heavy, poorly drained gley soils on the valley floor; meanwhile the much larger surrounding hill catchment generates dispersive pallic and loess sediment that overwhelms the small rated network yet pays no targeted rate. Compounding it, the lower Wairiri Stream just outside the rated boundary is “heavily constricted by willows, blackberry and other invasive weeds”, causing backwater flooding into the rated land around six or seven times per year – a cross-agency responsibility gap that no single agency currently owns. A new LiDAR-derived waterway layer lifted the rated network from ~14 km of classified drains to 39 km of channels, mapped a further ~126 km of informal overland flow paths inside the rated catchment, and put ~870 km on the table at the wider catchment scale. eDNA fish surveys recorded eight species including the Nationally Critical kōwaro/Canterbury mudfish (whose presence brings DOC into the conversation), Nationally Vulnerable īnanga, and the brown trout that explain Fish & Game’s seat at the working party.
The plan responds with catchment-scale approaches tailored to the foothill setting – transformative practice through Farm Environment Plans and Stormwater, Drainage & Watercourse Management Plans under SDC’s Stormwater & Drainage Bylaw 2025, a templated FEP for the very small landholders (only 23 parcels in the rated area, just 10 over 4 ha), strategic land-use change with an explicit recommendation to expand the rated catchment area through a variable rate that captures the hill contributors, smart drainage monitoring aligned with SDC’s CORDE transition over three years, and a phased shift away from blanket mechanical sediment removal – alongside reach-scale tools focused on erosion control for the pallic hill country, riparian buffers (5 m minimum, 10–15 m where space allows), event-based sediment traps on ephemeral channels, two-stage channels, lineal wetlands and detainment bunds. The draft was sent to SDC for sign-off on 13 May 2026 and works in conjunction with the Implementation Guide first developed for the Ararira/LII pilot, with implementation to be staged through SDC’s planned consenting for routine maintenance and discharge across the six schemes that share that pathway.
Combined Te Waihora Catchment Management Plan
A single CMP covering four lake-edge land drainage schemes – completing the Selwyn District programme with a combined plan that takes catchment-scale thinking to the scale of the whole Te Waihora margin.
The Combined Te Waihora Catchment Management Plan (AQU02-22072-02, June 2026) is the fourth and largest plan in Selwyn District Council’s seven-catchment programme – a single document covering four neighbouring lake-edge land drainage schemes: Greenpark (2,243 ha), Ellesmere (3,550 ha), Leeston (10,749 ha – by far the largest in the district) and Taumutu (986 ha), totalling ~17,528 ha around the margin of Te Waihora/Lake Ellesmere. The plan treats them together for sound reasons: boundaries between them are “indistinct because of the minimal elevation changes”, they share gley-dominated wetland-origin soils, their drainage performance is governed by the same Te Waihora lake-opening regime (under the 1990 National Water Conservation Order, co-held by Te Rūnanga o Ngāi Tahu, DOC and Environment Canterbury), and they offer obvious efficiencies of scale – one consent strategy, one Working Party, one mapping pipeline and one shared toolbox. The Working Party – Te Komiti Waiora – expands here to include Wairewa Rūnanga, the Lake Settlers Group and the Eastern Plains Land User Group alongside Te Taumutu Rūnanga, Te Tuahuriri Rūnanga, Te Rūnanga o Ngāi Tahu, the Land Drainage Committee chairs, DOC, Fish & Game, ECan and SDC.
Authored by EOS Ecology with Aqualinc Research, the plan diagnoses four catchments that share a context but differ markedly in detail. Greenpark – overlain by a continuous aquitard – has no recorded springs and behaves much like Osbornes (depauperate fish community of shortfin eel and goldfish only; standing water, low DO, very high conductivity hinting at coastal salt influence). Ellesmere has named natural waterways (Baileys Creek, McGraths Creek, Silverstream, Snake Creek) and eight fish species. Leeston is the heavyweight – 200+ km of rated drains, the only urban area in the four catchments (Leeston township), and the richest fish assemblage including the Nationally Critical kōwaro/Canterbury mudfish, with the Hanmer Road weir chain as a defining fish-passage issue. Taumutu is the only one of the four that discharges directly to the coast – through piped culverts driven through the gravel shoreline – and includes Muriwai/Coopers Lagoon (excluded from this plan and managed directly by Te Taumutu Rūnanga under its own plan). A new LiDAR-derived waterway layer (built and ground-truthed by our GIS team) re-mapped the combined channel network from ~270 km of rated drains to ~529 km of total channels, with a further ~1,371 km of informal overland flow paths that had never previously been captured.
Across the four catchments the plan responds with five catchment-scale approaches – transformative practice through Farm Environment Plans and Stormwater, Drainage & Watercourse Management Plans under SDC’s Stormwater & Drainage Bylaw 2025; strategic land-use change including the proposal for a continuous lake-edge protected landscape from Greenpark through to Leeston explicitly linked to Whakaora Te Waihora (realisable with only modest additional land acquisition because most of the margin is already reserve or conservation land); simplifying the awkward ten-piece Leeston rated boundary that currently cuts off the top of Taumutu; smart drainage monitoring aligned with SDC’s CORDE transition; and a phased shift away from blanket mechanical maintenance – alongside a 24-tool reach-scale toolbox built around the lake-edge reality. Several tools are new for the combined plan: large-scale two-stage channels for the perennial mainstems, regrading bunded margins so that floodwater can return to channels, waterway naturalisation and re-meandering of historically straightened natural waterways (Baileys Creek, McGraths Creek, Birdlings Brook), a flood-detention basin for the urbanising Leeston township, īnanga spawning habitat restoration in lake-proximal Taumutu and Leeston (the only confirmed historical spawning site being Waikekewai Creek per Taylor et al. 1992), and the deliberately counter-intuitive protection of kōwaro habitat through fish-passage barriers that exclude trout. Sea-level rise sits behind the whole plan as a load-bearing constraint – “sea level rise is already occurring and is certain to continue” – with the June/July 2013 flood and 2050 SSP8.5 inundation overlays used to frame future risk. The plan is in design-ready state for final delivery to SDC, after which implementation will be staged through the Implementation Guide first developed for the Ararira/LII pilot, completing the seven-catchment programme.
Focus Catchment Map Series
A nationwide map-based state-of-catchment resource – 52 publications across eight regions and 3.7 million hectares – developed by EOS Ecology as the National Technical Support Team for the Wai Connection – Tatai Ki Te Wai programme.
The Focus Catchment Map Series (FCMS) was developed by EOS Ecology as part of our role as the National Technical Support Team for Wai Connection – Tatai Ki Te Wai – a Ministry for the Environment-funded catchment-group support programme run by Mountains to Sea Conservation Trust between 2023 and 2025, supporting over 400 community and farmer-led catchment groups across Aotearoa New Zealand. The FCMS is the science backbone of that programme: a map-based state-of-catchment resource that compiles data from more than 150 national, regional and local sources into 90+ page publications covering six focus areas – parent catchment overview, factors affecting catchment processes, land management, water quality, ecological data, and connection to the coast – designed to give catchment groups a clear picture of their catchment, surface knowledge gaps, and inform their priorities.
We piloted the FCMS template with the Hakataramea Sustainability Collective, in close consultation with Environment Canterbury to ensure it complemented – rather than duplicated – regional council outputs like the Catchment Context, Challenges & Values (CCCV) mapping for Freshwater Farm Plans. Our GIS and science teams built the data workbenches that source, standardise, quality-check and analyse the underlying datasets – encompassing land cover class, climate, geology, topography, past and present land cover, protected areas, threatened environments, soils, modelled subcatchment sediment yield, and site-specific monitoring of water quality (freshwater and coastal), macroinvertebrates and fish – and our science interpreters and designers turn that material into 30+ maps and 50+ tables per publication, with the plain-English commentary that lets non-technical end users navigate it confidently.
Between January 2024 and June 2025 we produced 52 FCMS publications across eight regions, covering 3.7 million hectares – processing over 2.8 million raw monitoring data points, mapping and analysing data from more than 9,000 sites, and running 47 in-person science workshops to take catchment groups through their FCMS. Feedback from project operators, catchment groups, councils and iwi has been resoundingly positive, with Environment Canterbury describing the FCMS as an output that takes “a large quantity of information and present[s] it in an easy to access, visually appealing and scientifically accurate way”. The FCMS framework continues into 2026 with a focus on farmer-led catchment groups, building on the consistent national methodology that lets groups compare their catchment with others and ties their local picture back to the national- and regional-scale datasets used in plans and management strategies.
Wellington Water Integrated Catchment Management Plans
Stage-2 ecological assessments of five Wellington urban catchments – locating the city’s surviving open watercourses, mapping their ecological values, and surfacing the data gaps and management priorities that need attention as Wellington Water Limited’s Integrated Catchment Management Plans evolve.
Wellington’s natural watercourses have been so heavily modified by urbanisation that most now run through pipes. Wellington Water Limited (WWL) commissioned EOS Ecology to deliver high-level Stage-2 ecological assessments for five of its Integrated Catchment Management Plan (ICMP) catchments between 2016 and 2018: the Lambton Harbour catchment (Wellington CBD and surrounding hill suburbs), Evans Bay (Hataitai, Kilbirnie/Rongotai and much of the Miramar Peninsula), the South-east Coast catchment (eastern Miramar Peninsula through to Tarakena Bay), Island Bay–Houghton Bay (Island Bay, Berhampore and surrounding suburbs, with the Taputeranga Marine Reserve as its receiving environment), and Lyall Bay (Lyall Bay and most of Wellington International Airport). Together these assessments cover hundreds of remnant open channel sections across more than 160 separate watercourses – many of them effectively ‘hidden’ from public and regulatory awareness despite still supporting freshwater biota.
Each assessment was deliberately scoped as a desk-based exercise informed by existing data, information from local experts and physical site visits – no new ecological sampling was undertaken – and produced for each catchment a description of the surviving watercourses, a preliminary amenity-value assessment of the remnant open channels, and a summary of the relevant marine receiving environment. The findings tell a consistent Wellington story: most of the original stream length has been piped; the small number of permanently flowing surface streams that remain often punch above their weight ecologically (banded kōkopu and kōura confirmed in the upper Island Bay catchment and in the Papawai, Moturoa and Waimapihi streams of the Lambton Harbour catchment); and the harder, more enclosed receiving environments such as Lambton Harbour and Evans Bay show measurable accumulation of stormwater contaminants in marine sediments, while the exposed open-coast catchments – South-east Coast, Lyall Bay and Island Bay–Houghton Bay – face very different dispersal regimes that broadly attenuate contaminant build-up.
Each report flagged the critical knowledge gaps that would otherwise impede robust ICMP decision-making – particularly the near-absence of aquatic macroinvertebrate and comprehensive fish-survey data, the lack of water and sediment quality information from the natural watercourses themselves, and the often complete absence of any ecological data from the piped network – and identified concrete opportunities for enhancing natural values where stormwater management overlaps with stream ecology. Recommendations consistently included identification and remediation of fish migration barriers in both open and piped sections, increasing instream habitat complexity, ecological enhancement of Town Belt and reserve riparian zones (weed control, native plantings, gradual replacement of exotic trees), and broad adoption of Water Sensitive Urban Design (WSUD) approaches – small-scale stormwater treatment such as swales, tree pits, rain gardens and permeable paving, rainwater capture and reuse, and behaviour change around contaminants entering the network. The five reports collectively gave WWL the ecological baseline it needed to take each catchment through the next stages of ICMP development.
Te Ruakanakana/Lake Elterwater Catchment Sediment Management
Advanced LiDAR-based spatial analysis to identify sediment and nutrient sources in a data-limited Marlborough catchment – turning gaps in conventional water-quality monitoring into a quantified, spatially explicit roadmap for landowner-led restoration.
Te Ruakanakana/Lake Elterwater is a shallow, intermittent lake (roughly 53–73 ha) in the 1,607 ha Te Ruakanakana subcatchment of the Flaxbourne River in eastern Marlborough – a landscape dominated by highly erodible pallic (argillic) soils that disperse easily and are difficult to settle once suspended in water. The lake is hyper-eutrophic and dried out four times between 2000 and 2020. EOS Ecology was commissioned by the Lake Elterwater Restoration Group, with funding through the Access 2 Experts (A2E) programme, to identify the primary sources of sediment and nutrient enrichment affecting the lake as the foundation for a future Catchment Management Plan. Because the A2E funding explicitly excluded any field sampling, our brief was to identify likely sources from spatial first principles rather than wait for years of monitoring data to accumulate. The project was undertaken in close collaboration with the Group’s technical specialist from WetlandsNZ, who supplied the initial subcatchment boundaries, with NZ Landcare Trust facilitating the landowner engagement in November 2024. Local iwi – Ngāti Toa Rangatira, Rangitāne o Wairau and Ngāi Tahu – were acknowledged but not formally consulted; the report flags this as a project limitation.
Our June 2025 report (BEC01-24032-01) combined the landowner conversations with high-resolution LiDAR-derived digital elevation models and aerial imagery to build a suite of bespoke geospatial layers – fine-resolution slope, land cover classified from over 200 training samples, overland flow paths, waterway lines, watersheds, and subcatchment boundaries adjusted to reflect the moderating influence of the catchment’s four large irrigation reservoirs on downstream sediment transport. A Relative Elevation Model derived from the LiDAR, alongside digitised topographic maps from 1939 to 2019, allowed us to detect paleochannels and historical lake-edge geometry that informed the analysis. The work delineated 28 subcatchments and 324.8 km of flow paths – over a tenfold increase on the data layers previously available – and produced a reservoir-aware erosion-risk matrix that flagged subcatchments 1 and 20 as the highest priority for intervention after the moderating effect of the reservoirs was accounted for. The methodology was deliberately designed to be replicable across other data-limited catchments.
From that base, the report sets out a suite of targeted mitigation options developed alongside the landowner site visits – maximising the sediment and nutrient retention function of the four large irrigation reservoirs through rāupo (Typha orientalis) plantings on their banks and lineal seepage wetlands in the flat ephemeral channels downstream, retrofitting small-scale sediment traps and planted micro-wetlands into existing culverts, and restoring a meandering channel and head-of-lake wetland that would add at least 650 m of channel based on the pre-1970s topographic geometry (with proximity to the newly opened Whale Trail unlocking eco-tourism, biodiversity-credit and potential future carbon-credit co-benefits for landowners). Targeted cut-face erosion control draws directly on EOS Ecology’s own Port Hills Christchurch trials – Flexterra HP-FGM hydromulch with silver tussock (Poa cita) and NZ ice plant (Disphyma australe) – and the existing good land-management practices already in the catchment are explicitly recognised. We also designed a three-tier event-based water-quality monitoring framework, anchored on a primary site at subcatchment 17b (the main inlet, draining 66% of the catchment) and built around telemetered autosamplers measuring nitrate-N, dissolved reactive phosphorus and turbidity calibrated to suspended-sediment concentration – the regime that actually captures the storm-driven pulses that mobilise pallic soils. Together, these outputs give the Restoration Group and the landowners on the ground a scientifically robust, spatially explicit roadmap for prioritising interventions and building out a Catchment Management Plan.