Makara Estuary Baseline and Construction Monitoring Plan (MEBCMP)
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Makara Estuary Baseline and Construction Monitoring Plan (MEBCMP) Prepared for Meridian Energy Ltd eCoast Ltd Marine Consulting and Research PO Box 151 Raglan New Zealand Telephone: +64 21 423 224 Email: [email protected] MEBCMP Contents 1 INTRODUCTION ...................................................................................................................................... 1 1.1 THE SITE ...................................................................................................................................................... 1 2 METHODOLOGY ...................................................................................................................................... 3 2.1 PROPOSED LOCATIONS OF MONITORING ............................................................................................................ 3 2.2 BIOLOGICAL DATA COLLECTION ........................................................................................................................ 4 2.3 BIOLOGICAL DATA ANALYSIS ............................................................................................................................ 6 2.4 SEDIMENT DEPOSITION DATA COLLECTION ......................................................................................................... 9 3 REPORTING ........................................................................................................................................... 10 4 REFERENCES ......................................................................................................................................... 11 APPENDIX 1 – MAKARA ESTUARY BASELINE AND CONSTRUCTION MONITORING PLAN ................................ 13 APPENDIX 2 – EXPERT WITNESS EVIDENCE OF SHAW MEAD FOR MILL CREEK ENVIRONMENT COURT PROCEEDINGS ................................................................................................................................................ 15 List of Figures Figure 1.1. Locality map of Makara Estuary (Source: Google Earth). ....................... 2 Figure 2.1. Sampling locations for the MEBCMP. Site 1 also includes cobble habitat monitoring (blue box). ................................................................................................. 8 Figure 2.2 A plate being buried on a tidal flat (http://www.geog.sussex.ac.uk, 2004). 9 i MEBCMP 1 Introduction The Makara Estuary Baseline and Construction Monitoring Plan (MEBCMP) has been prepared on behalf of Meridian Energy Ltd (MEL) for one of the Conditions of Consent for the Mill Creek: “The consent holder shall engage an appropriately qualified and experienced estuarine ecologist to prepare and submit a Makara Estuary Baseline and Construction Monitoring Plan ("the MEBCMP") to the Manager, Environmental Regulation, Wellington Regional Council, for approval at least 20 working days prior to the proposed start date of the baseline water quality monitoring programme site.” The condition specifies that the baseline monitoring shall commence at least 6 months prior to bulk earthworks. At this stage, dry-season (March 2012) and wet- seaon (September 2012) baseline monitoring is proposed to time with the commencement of constrution in October 2012. The MEBCMP has been developed using the details provided in the condition – attached as Appendix 1. Appendix 2 is the Environment Court Evidence for the Mill Creek Resource Consent for Environment Court compiled by Dr. Shaw Mead, which includes the lastest of a series marine and estuarine investigations associated with Project Westwind “State of the Environment Assessment for Makara Beach, Makara Estuary, Ohau Bay and Oteranga Bay – Wellington coast 2010” compiled by Dr.’s Mead and Haggitt (the ecologists engaged by MEL), and list the previous 5 investigations dating back to 2004. CV’s of Dr’s Shaw Mead and Tim Haggitt, the ecologists engaged to undertake the MEBCMP, accompany this document. 1.1 The Site The entrance to Makara Estuary is located at the northern end of Makara Beach (Ohariu Bay), west of Wellington (Figure 1.1), and is fed by the Makara River. The estuary proper is bounded by the seaward entrance and the location where highest 1 MEBCMP spring tides encroach up river (approximately 1.5 km). The estuary is approximately 80 m wide at its widest point near the entrance and narrows to 20 m wide 1 km from the entrance. It incorporates 2-3ha of saltmarsh, and is mostly 1-3 m deep. The estuary margins are modified and vegetated with various scrub species, saltmarsh, terrestrial grass and weed, which provide reasonable habitat for whitebait spawning (Taylor and Kelly, 2001). Makara Estuary Figure 1.1. Locality map of Makara Estuary (Source: http://mapping.gw.govt.nz/gwrc/). 2 MEBCMP 2 Methodology The monitoring methodology will expand on the sampling undertaken at Makara Estuary in February 2010 (Appendix 2). Monitoring will target macro and meio-fauna abundance and diversity, and sediment deposition rates. Monitoring will be undertaken every 6 months. At this stage, the base-line monitoring data will be collected for the dry-season (March 2012) and wet-seaon (September 2012) in order to time with the commencement of construction in October 2012. Six-monthly data collection will be undertaken for the duration of construction and for 12 months following construction. 2.1 Proposed Locations of Monitoring Three locations within the estuary will be monitored (Figure 2.1): 1. the inner entrance (previously sampled in 2010); 2. 400 m upstream of the entrance, and; 3. 800 m upstream of the entrance. At each site, biological and physical sampling will be undertaken. A table of GPS positions for each sample location will be provided with the first report (Baseline Monitoring Report I). In addition, general environmental health of the estuary will be recorded with photography and described during each monitoring visit. For example, details of any particular characteristics that are noted during monitoring which may influence the results e.g. activities or incidents occurring in the Makara Catchment, any changes to the extent of the saltmarsh, presence of seagrass, erosion of the banks, stock encroachment, etc. Erosion of the estuary/river banks has been observed to be a contributor to sediment inputs (Section 30, Appendix 2). The banks of the estuary will be video-surveyed along its 1.5 km length. Areas of active erosion (e.g. near the Opau Road intersection) will be measured to easily identified benchmarks (e.g. fence posts, 3 MEBCMP large trees, road edge, etc.). Both the video-survey and benchmarking will provide information of additional sediment inputs directly into the estuary. Further data is also available to assess environmental characteristics that my influence the results – the Baseline Aquatic Monitoring. This monitoring has been undertaken for up to 5 years in some locations and includes macro-invertebrates, temperature, dissolved oxygen, pH, suspended sediments, NTU and visual clarity assessments at 16 sampling sites throughout the catchment. Rain gauges at Mill Creek and West Wind will provide additional information and any "observations" of activities occurring within the catchments which may contribute to deposition of sediment in the estuary between monitoring regimes1 will be recorded as part of the Baseline Aquatic Monitoring Plan (BAMP) for Mill Creek. 2.2 Biological Data Collection Monitoring of species composition has regularly been used to consider sedimentation-related effects in estuaries; this is often in association with specific events or modifications to the estuary or catchment, as is the potential in the present case (e.g. (Turner & Riddle, 2001; Gibbs and Hewitt 2004). Different species are associated with different types of sediment, especially infaunal species such as bivalves and polycheates (marine worms). Thus, by assessing the biological community composition and how it changes (or does not change) with time, sedimentation rates/impacts can be evaluated. Data collection will be the same as used at other GWR estuaries (e.g. Robertson and Stevens, 2008), with respect to numbers of replicates (n=12), size of quadrats (0.25 m2), and sediment sample collection (250 gms from the top 20 mm of sediment cores). The general sampling protocol will: 1. Establish what species and communities are present at each of the three locations within the Makara Estuary (baseline data for dry and wet seasons) prior to the proposed works being undertaken; 1 The BAMP includes water quality monitoring after every rainfall event exceeding 20 mm over 24 hours and 3 monthly for macro-invertebrates. 4 MEBCMP 2. Determine what species and communities are of value to employ as indicator species; 3. Develop “effect thresholds” that will constitute an “effect” (defined as percent change) for those indicator species and communities; 4. Undertake temporal sampling during and following the construction phase of the proposed works, and; 5. Undertake analysis of temporal data following each sampling period to gauge magnitude and direction of effects (if any) through time associated with the proposed works. Note: Due to the unavailability of a comparable control location within the general region of Makara Estuary or along the southern NW coast, (see Robertson and Stevens 2007) the focus of the sampling design will be to measure possible changes through space and time before and after the proposed works only within the Makara Estuary. However, based on the methodology proposed we feel that detection of environmental effects will be