Thursday, 16 th April 2015

Transcription

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2 Integrated Catchment Management age e Committee Thursday, 16 th April 2015

3 Sources of contaminants to rivers in the Waikato region Dr Bill Vant

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5 Waikato-Waipa contaminant monitoring River monitoring, 20 locations (WRC, NIWA) Flow continuous (m 3 /s) Concentration monthly (g/m 3 ) Point sources, 19 locations ( consent monitoring ) Flow reported daily-to-monthly Concentration ti daily-to-monthly thl Load = Σ(flow concentration) (g/s, kg/d, t/yr)

6 For example, various sites, River sites Flow (m 3 /s) [Total N] (g/m 3 ) Load (t/yr) Waikato-Taupo Waikato-Narrows Waipa-Whatawhata Waikato-Tuakau , Point sources Hamilton sewage Horotiu meatworks Ngaruawahia sewage

7 Loads from point sources, Hamilton Cambridge Tokoroa Te Kuiti Tuakau/Pukekohe kkh Otorohanga Huntly Te Awamutu Ngaruawahia Te Kauwhata Meremere Kinleith mill Horotiu meatworks Wairakei PS Tuakau rendering Hautapu dairy Te Awamutu dairy Te Rapa dairy Ohaaki PS Nitrogen load (t/yr) Hamilton Cambridge Tokoroa Te Kuiti Tuakau/Pukekohe k k Otorohanga Huntly Te Awamutu Ngaruawahia Te Kauwhata Meremere Kinleith mill Horotiu meatworks Wairakei PS Tuakau rendering Hautapu dairy Te Awamutu dairy Te Rapa dairy Ohaaki PS Phosphorus load (t/yr)

8 Contaminant accounting (NPS-FW 2014) Determine load carried by river (A) Identify background or natural contribution ti (B) Add up contributions from all point sources (C) Calculate contribution from landuse, D (= A B C)

9 For example, nitrogen, Waipa catchment A,, Waipa-Whatawhata apa aa aa 4069 t/yr B, Background (= 3093 km 0.3 t/km 2 /yr = 928 t/yr) C, Point sources Otorohanga sewage 14 Te Awamutu sewage 11 Te Kuiti sewage 26 Te Awamutu dairy factory 15 Sum, point sources 66 D, Landuse (= A B C) 928 t/yr 66 t/yr 3075 t/yr

10 Three sub-catchments, Nitrogen load (tonnes/year) Phosphorus load (tonnes/year) Upper Upper Waipa Waipa Lower* Lower* Taupo Background Point sources Landuse Taupo Background Point sources Landuse *Ignoring inputs from upstream catchments

11 Sources of nutrients, Waikato / Waipa, Loads in river and from point sources are measured Point sources: about 7% of the overall nitrogen load and 18% of the overall phosphorus load Background 29% and 35%; landuse 61% and 45% Nitrogen Phosphorus 0% 25% 50% 75% 100% Taupo Background Point sources Landuse

12 PS loads, changes during the decade Hamilton Cambridge Tuakau/Pukekohe Huntly Te Awamutu Phosphorus load (t/yr) Te Kauwhata Phosphorus: 30% reduction Kinleith Horotiu meatworks Tuakau rendering Te Awamutu dairy Te Rapa dairy Nitrogen: 7% reduction pre

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14 Sources of nutrients, Hauraki Rivers, Loads in river, and from sewage/industries are measured Point sources: about 8% of the overall nitrogen load and 25% of the overall phosphorus load

15 E. coli loads from point sources, Te Kuiti Hamilton Otorohanga Tuakau/Pukekohe Ngaruawahia Te Awamutu Huntly Meremere Te Kauwhata E. coli load (Gcfu/d) 0 1,000 2,000 Horotiu meatworks Tuakau rendering Hautapu dairy Te Awamutu dairy

16 E. coli loads from point sources, E. coli load (Gcfu/d) 0 1,000 2,000 Te Kuiti Hamilton Otorohanga Tuakau/Pukekohe Ngaruawahia Te Awamutu Huntly Meremere Te Kauwhata ata Horotiu meatworks Tuakau rendering Hautapu dairy Te Awamutu dairy The combined point source load was equivalent to about 5% of the corresponding value for Waikato Tuakau

17 E. coli loads from point sources, E. coli load (Gcfu/d) 0 1,000 2,000 Te Kuiti Hamilton Otorohanga Tuakau/Pukekohe Ngaruawahia Te Awamutu Huntly Meremere Te Kauwhata Horotiu meatworks Tuakau rendering Hautapu dairy Te Awamutu dairy The combined point source load Was equivalent to about 3% of the corresponding value for Waikato Tuakau

18 Conclusions Monitoring data can be used to identify the contributions of different sources of contaminants Overall, point source discharges contribute 7% of the N and 18% of the P to the Waikato/Waipa (at Tuakau). Landuse mostly pastoral farming contributes about 60% and 45%, respectively. Non point sources include background or natural sources. These can be appreciable (c. 30%). Overall, point source discharges are a minor source of E. coli. But they can be locally ll important. t

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20 Why the four contaminants? Contaminant Relevance Microbes (E. coli) ) Human health: safe swimming, waka ama, kai gathering, g, boating, angling etc Cultural acceptability (measure of faecal pollution) Livestock health: drinking water Domestic & industrial use: treatment needs Sediment: Suspended sediment Water clarity Turbidity Nutrients: Nitrogen (TN, Nitrate, DIN) and Phosphorus (TP, DRP) Nitrogen toxicity: Ammonium & nitrate Aesthetics, safe swimming, waka ama, kai gathering, boating, angling Cultural acceptability Ecosystem health (light, primary production, visual feeders - fish, birds) Sedimentation: drainage/flooding, dam volume Promotes plant growth e.g., g, nuisance algal blooms with aesthetic, toxic (cyanobacteria) and ecosystem health impacts Toxic to aquatic life

21 Raising understanding: contaminant pathways Atmospheric N Leached N N fixation/n fertiliser slips & soil erosion sediment P Runoff sediment P P fertiliser P to stream bugs N in urine Rock mineral P N as gas livestock excreta sediment N P bugs bank & gully erosion

22 About FMUs Areas catchment is divided into for: setting freshwater objectives and limits (attribute bands) freshwater accounting and management purposes NPS for Freshwater Management requirement, allows for: identical objectives and methods amongst FMUs different policies and methods within an FMU

23 CSG s preferred FMU option 1 Upper Waikato Huka Falls to Karapiro 2 Middle Waikato Karapiro to Ngaruawahia 3 Lower Waikato Ngaruawahia to Port Waikato 4Waipa Waipa River Catchment Five water quality monitoring i sites that t would be part of the network to monitor each FMU. (N.B. It is possible to monitor an FMU from a site located outside it.) 5 Shallow lakes Selected lowland lakes nested within their local catchment

24 Reasons for the preferred option Identifies main catchments Separates Waipa and Waikato catchments Separate treatment of selected lakes Aligns with catchment management zones Recognises Hamilton urban and peri-urban area Recognises impounded versus flowing water in Waikato River Partly combines geomorphic or hydrogeological units Existing monitoring sites can monitor each FMU (with some accounting/correction) Reflects issues to be managed Aligns with sub-regions in WRA s Waikato River Report Cards

25 Healthy Rivers Policy Process CSG outcomes The policy cycle and technical input Desired Values CSG Focus Statement/Vision & Strategy e.g., safe to swim, take food, provide well being May be enriched narrative below that Assess options against Vl Values & risk ik Consensus? Seek further scenarios? CSG deliberations Determining water quality levels (N, P, Sed., bacteria) consistent with Desired Values TLG advises, using: Nti National objectives Existing information Experts input Scenario Analysis looking at future options for limiting point and non point losses from land to ensure water quality is consistent with ihdesired dvl Values Integrated assessment across Values to provide CSG with social, economic, cultural & ecological analysis TLG, using experts for: Predictive modelling Integrated assessment

26 Graham s Creek Final design and rating classification changes Doc #

27 Key information Design provides greater level of flood mitigation (at least 50 yr) Annual Plan budget of $600,000 on track Consents lodged with WRC and TCDC Classification apportionment shift from stopbank to channel 27 properties particularly affected Ratepayers Assoc and Working Party wish to see the direct benefit costs shared across a wider area Final works will achieve both flood mitigation and Final works will achieve both flood mitigation and environmental improvements

28 Graham s Creek approved design

29 Channel direct benefit area

30 Recommendations That the report Graham s Creek Classification Changes (Doc # dated 23 March 2015) be received for information, and That the proposed rating classification changes be endorsed.