All freshwater lakes in New Zealand are currently being impacted by numerous changing pressures of both anthropogenic and climatic origin. The aim of this study was to design a programme to monitor and manage Te Waihora in the most efficient and cost-‐ effective manner within the context of an integrative monitoring programme for Te Waihora as envisaged by Hughey (2015). This thesis includes an assessment of the physical and historical situation of Te Waihora and of current freshwater legislation. The research designs a new integrative water quality monitoring programme to identify Te Waihora water quality state and trends, and considers the ongoing role and integration of current stakeholder monitoring.
Te Waihora and its catchment is a complex, interconnected freshwater system consistent with its identity as an ICOLL. Initial compilation of information on existing monitoring programmes provided an overall review of what is currently being monitored and where. This included both small, localized programmes and catchment-‐wide programmes and showed where data collection gaps occurred.
A robust, overarching and future-‐focused water quality monitoring programme for Te Waihora was designed using predetermined criteria to validate the selection of tributaries, sites, parameters and frequency. This integrative water quality monitoring programme proposes monthly monitoring of the six lake and eight tributary sites for all regulatory parameters (NPS-‐FM [2014] amended 2017, and CLWRP) as well as parameters of specific interest in Te Waihora, such as nutrients and sediment. Additional monitoring is proposed for further specific parameters (emerging contaminants, heavy metals, PAH) at 1 to 5 yearly frequencies. Recommendations to achieve the overarching integrative objectives, for foreseeable future requirements for management and modelling, were made. The “robustness” of all aspects of the monitoring (practical and financial) is acknowledged as essential for longevity.
A comparison of this design with existing stakeholder monitoring was used to show where any gaps or omissions occurred. Recommendations have been made on potential
ways to address these gaps, through integration and modification (where applicable) of existing stakeholder monitoring and the creation of new monitoring sites. The current collaborative management of this lake and its catchment, led by Ngāi Tahu and the local authorities (ECan, SDC and CCC), has created a regime where cost-‐efficiencies can be made by the integration of existing programmes and possible changes or additions. The implementation of this programme can benefit from this approach.
6.1 Limitations of this research
A monitoring programme may be limited in its usefulness for management if all factors influencing its design are not clearly documented. In this case, one such influencing factor is the climate. This research programme included measurements and assessments made from 2015 to 2017. In 2015–2016, the Canterbury region was in the grip of a serious drought, as well as experiencing a steep increase in land use intensification and associated irrigation. One advantage this may have, is to highlight the role of climatic conditions now, and for any future climate change. However, it also emphasises the need for regular programme reviews if the design proves to be inappropriate for wetter seasons. Reviews build some degree of resilience into the monitoring programme itself, but as noted previously, any changes require serious consideration of the break in continuity they cause.
This proposed programme does not include the monitoring of localized improvement initiatives, which require more specific monitoring programmes and could involve citizen science for particular attributes or parameters. Many of the proposed programme parameters are not as relevant to localised improvement initiatives, as they are to overall trend detection. Instead, the proposed programme tributary monitoring sites are chosen to show cumulative results for the whole catchment.
6.2 Recommendations for further research
The following recommendations are made for further research to reduce uncertainties inherent in this proposed programme:
• The validation (as per the recommendations in Chapter 5) of new sites,
parameters and frequencies and the inclusion of a new tributary rather than an existing tributary, as well as a new lake site, will require significant further research. This could be carried out by the Waterways Centre for Freshwater Management and/or LU/UC students (as noted).
• Recommendations for some research to establish a valid relationship between
turbidity, TSS and clarity (specific to each site) to decrease the cost of testing all three, may be beneficial. It may not however, be prudent for the anticipated future use of data, as one of Te Waihora’s major problems is sediment load, and the continued monitoring of TSS (as well as VSS) is strongly recommended.
• The effect of extreme rain events on the areas of Te Waihora that are potentially
most impacted by flood sediment loads is a topic to consider, particularly with a view to future change in climate patterns. The contribution of tributary sediment and nutrient loads has had some research (e.g., Kelly et al., 2014; Mitchell, 2012) but no routine monitoring. The recommendation would be to carry out future research for monitoring and flow recorder sites, over a range of flow conditions, to enable accurate load data to be available for management purposes. As noted previously by others, one area where flood sediment and nutrient run-‐off loads are likely to be inaccurate is Banks Peninsula. Flood flows carry a disproportionately large fraction of both sediment and nutrient load (Elliott & Sorrell, 2002).
• Current research into the effects of the updated opening/closing regime (e.g.,
the effect on fish spawning or lake flies), sediment, or N and P metabolism within the lake, will all need to be taken account when the monitoring programme is reviewed.
• Water quality monitoring of the effects of localized improvement initiatives
effectiveness of the initiatives. This monitoring could be planned and initiated by stakeholders such as WET or LU/UC and carried out by local communities.
• Current knowledge of emerging contaminants will dictate their inclusion in the
routine monitoring programme. Land use may dictate the contaminants of concern, such as veterinary products, urban wastes or horticultural spraying. This type of research should also be considered in the routine monitoring programme review.