Annual report 2006-2007 - Taranaki Regional Council

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10. Water quality in the Kahouri catchment 92 The water quality of the Kahouri Stream has been assessed briefly under separate headings in regard to both chemical and biological aspects. In particular, emphasis has been placed upon components in the various discharges that have the potential to influence its suitability for various water purposes including instream uses such as wildlife and aquatic biota. The chemical water quality in the main Kahouri Stream channel could be described as good, bearing in mind the influence of catchment land use and channel and riparian vegetation characteristics. As well as waste contribution from the various industries monitored as part of the Kahouri programme, there are wastes from various agricultural activities both of a point source and diffuse nature which also influence the water quality of the stream. A concern with the abattoir discharge is the contribution of nutrients to the Kahouri catchment and, ultimately, to Lake Rotorangi. Previous work has demonstrated that, after the Stratford municipal oxidation pond discharge, the discharge from the abattoir is the second most significant single point source contributor of nutrients to the upper Patea catchment. Monitoring of Lake Rotorangi indicates that the lake continues to be mesotrophic to mildly eutrophic, suggesting that nutrient enrichment is not occurring or is occurring at a very slow rate. It is noted that the combined discharges from dairy farms (both treated dairy shed wastes and pastoral run-off) are also comparatively significant sources of nutrients. In April 2007 the waste discharge from the Taranaki Abattoir raised the biochemical oxygen demand in the Kahouri Stream by more than 1 g/m 3 and therefore did not comply with special condition 1 of the Company’s discharge consent. There was also an increase in nutrient concentrations downstream of the discharge. Associated with these increases were some significant changes in macroinvertebrate community composition in the Kahouri Stream. Treated domestic waste from Transpower NZ Limited contributes a relatively minor amount of nutrients and both water chemistry and biological monitoring indicated no deterioration in water quality as a result of this discharge. Discharges from Taranaki Galvanizers have in the past had a significant influence on the water quality of the Kahouri Stream, particularly the small tributary which continues to receive zinc leachate. This is important from a toxicity standpoint. Stream biota, including macroinvertebrates, algae and fish species, are variously sensitive to zinc in soft waters of low buffering capacity such as those of the Kahouri system. Dilution effects reduce the zinc concentration to ‘safe levels’ (as defined by United States Environmental Protection Agency guidelines for aquatic species and ANZECC guidelines) at a point somewhere above the confluence of the large tributary with the main Kahouri Stream. It was noted in the 1998-1999 monitoring report that zinc levels in the small tributary, now piped, receiving the zinc leachate had fallen to one fiftieth of the concentration first found. The levels measured during the 2006-2007 monitoring year indicate that the amount of zinc leaching from the site appears to be continuing to stabilise. However, it is important to recognise that there have been a number of ‘'pulses’ of
higher zinc concentration over the time that results have been recorded. This phenomenon is common for leachate. Zinc concentration in the Kahouri remains below biota toxicity levels. 93 The chemical surveys are concerned largely with making an assessment of water quality by measuring the concentration of components of interest in discrete samples from selected sites. This gives an instantaneous representation of water quality but says little about temporal variations, particularly when only limited sampling is conducted each year. The biological surveys give an indication of what has happened during the days, weeks or sometimes months, prior to sampling. Any occurrence of continuous gross pollution within this time frame will be reflected in the composition of the macroinvertebrate community at each site. A macroinvertebrate community index (MCI) and semi-quantitative MCI (SQMCIs) is calculated and, together with an assessment of the dominant species, these go toward making an overall assessment of the quality of the macroinvertebrate community for each site. Some sites are more suited than others to this form of monitoring, for example, stony riffles. Other sites in the upper reaches of the Kahouri catchment have muddy or weedy beds that influence the species that can live there. Therefore, the MCI and SQMCIs values and assessment of community composition is always discussed in relation to the physical habitat type. This summer survey of macroinvertebrate communities in the Kahouri Stream indicated that the communities directly downstream of the tributary that receives the Taranaki Abattoirs and Ballance Agri-Nutrients discharges were significantly different than those upstream, where taxa richness and MCI score were slightly healthier than median community conditions recorded previously at this ‘control’ site. There was a significant decrease in MCI and SQMCIS scores at the lower site, which may have been due to additional instream nutrients supplied by the tributary. This is likely to be due to the impacts from the abattoir, but this is unclear without further monitoring. Therefore it is recommended that additional sites be included in subsequent surveys to assess the impact of the abattoir discharge on this unnamed tributary. Further downstream at Flint Road, the macroinvertebrate community remained very similar in community structure and indicated similar stream ‘health’, although there was a recovery in the SQMCIS score at this site. None of the rest of the Kahouri Stream sampling sites further downstream showed any significant adverse effects as a result of industrial discharges to this catchment, consistent with the absence of any significant heterotrophic growths on the stream substrate. The macroinvertebrate communities of the Kahouri Stream were generally characterised by moderate taxonomic richnesses at the time of this April 2007 survey despite a period of relatively low flows during the latter part of summer. These communities continued to support abundances of several ‘sensitive’ taxa at all main stream sites, from upstream of the Taranaki Abattoir, to the confluence with the Piakau Stream. All sites had relatively similar communities, particularly in terms of those taxa characteristic to each site. For example, eight taxa dominated the communities of nearly all of the six Kahouri Stream sites.
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Kahouri Stream Monitoring Programme
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Six complaints, which were logged a
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ii 2.7 Recommendations 37 3. Tarana
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iv 6.6.4 Recommendations from the 2
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vi List of tables Table 1 Resource
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Figure 6 Biological oxygen demand (
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Section 11 presents recommendations
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1.2.1 Other resource consents A tot
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Figure 1 Biological and chemical mo
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2. Taranaki Abattoir Co (1992) Limi
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10 Waste liquor and floor washings
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2.2.2 Water discharge permit 12 Sec
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24 March 2005, under Section 87(e)
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16 plant staff were made aware of t
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18 inspection, staff also outlined
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Dissolved oxygen (g/m 3 ) 35 30 25
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Dissolved Reactive Phosphorus (g/m3
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24 In comparing the results (upstre
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26 Biological survey The Council’
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SQMCIs Value 7 6 5 4 3 2 1 0 A C E
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2.6 Discussion 2.6.1 Discussion of
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Table 7 Summary of performance for
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34 Condition requirement Means of m
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36 1. THAT monitoring of air emissi
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3. Taranaki Galvanizers 3.1 Process
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Special condition 4 defines the mix
Page 56 and 57: 42 underneath the galvanising plant
Page 58 and 59: NH 4 -N (g/m 3 ) 44 Ammoniacal nitr
Page 60 and 61: 3.4.2 Air 46 Air monitoring in the
Page 62 and 63: 48 Table 14 Summary of performance
Page 64 and 65: 4. Egmont Tanneries Limited 4.1 Pro
Page 66 and 67: permit was issued by the Taranaki R
Page 68 and 69: 54 An additional inspection was und
Page 70 and 71: 56 Table 16 Results of summer low-f
Page 72 and 73: 58 In the 2006-2007 year, there was
Page 74 and 75: Table 19 Summary of performance for
Page 76 and 77: 62 In the case of Egmont Tanneries,
Page 78 and 79: 5.3 Monitoring programme The monito
Page 80 and 81: 66 Water chemistry The chemical wat
Page 82 and 83: Table 22 Summary of performance for
Page 84 and 85: 6. Contact Energy Limited (closed p
Page 86 and 87: 72 not suggest that discharges from
Page 88 and 89: 74 7. Contact Energy Limited (CCPS)
Page 90 and 91: 7.3.2 Biomonitoring surveys 76 One
Page 92 and 93: 78 Condition requirement Means of m
Page 94 and 95: 8. Fletcher Concrete & Infrastructu
Page 96 and 97: 8.3.2 Chemical sampling 82 The Tara
Page 98 and 99: 84 The stream at this site had a cl
Page 100 and 101: 8.6.5 Alterations to monitoring pro
Page 102 and 103: 88 what effects the discharge shall
Page 104 and 105: 90 Incidents may be alleged to be a
Page 108 and 109: 94 Most MCI scores were similar to
Page 110 and 111: 96 12. Summary of recommendations 1
Page 112 and 113: NH3 unionised ammonia, normally exp
Page 115: Appendix I Resource consents held b
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To Job Manager, B Jansma From Scien
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Figure 1 Biomonitoring sites in the
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Table 3 Macroinvertebrate fauna of
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MCI value 140 120 100 80 60 40 20 0
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Site E: Kahouri Stream (KHI000400)
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mayflies, elmid beetles, Archichaul
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Further downstream at Flint Road, t
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Annual report 2006-2007 - Taranaki Regional Council

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