Waimakariri tributary report
Report No. R09/11 ISBN 978-1-86937-927-8
Taryn Wilks Adrian Meredith
February 2009
Report R09/11 ISBN 978-1-86937-927-8
58 Kilmore Street PO Box 345 Christchurch 8140 Phone (03) 365 3828 Fax (03) 365 3194
75 Church Street PO Box 550 Timaru 7940 Phone (03) 687 7800 Fax (03) 687 7808
Website: www.ecan.govt.nz Customer Services Phone 0800 324 636
Waimakariri tributary report 2008
Executive summary
Water quality in the lower Waimakariri catchment, including Cam, Cust, Ohoka, Kaiapoi, Courtenay, South Branch/Otukaikino and the Styx Rivers have been monitored since 2000 by Environment Canterbury. Cessation of waste water discharge in 2005 and the initiatives to improve discharge methods of both Waimakariri District Council and Christchurch City Council have yielded significant water quality improvements in the Cam River and South Branch/Otukaikino. Water quality in the Ohoka, Cust and Styx Rivers has remained in a steady state, while water quality in the Kaiapoi River has shown signs of degradation. Concentrations of faecal indicator bacteria in Waimakariri tributary streams regularly exceed the contact recreation guideline of 550 MPN/100ml, resulting in very poor contact recreational grades. The sources are likely to be a mixture of natural (wildlife), agricultural (livestock), and discharges, but exclusion of livestock from stream banks and springheads hold most promise for reduced concentrations. High nitrogen concentrations are also an ongoing issue, and it is therefore recommended that monitoring of these tributaries (both water quality and ecosystem health) is continued. Additionally an investigation into declining water quality in the Kaiapoi River is recommended.
Environment Canterbury Technical Report i Waimakariri tributary report 2008
ii Environment Canterbury Technical Report Waimakariri tributary report 2008
Table of contents
Executive summary ...... i
1 Introduction ...... 1
2 Methods ...... 1 2.1 Data analysis ...... 4 2.1 Trend analysis ...... 4
3 Results ...... 5 3.1 Water physico-chemistry ...... 5 3.2 Nutrients ...... 6 3.2.1 Dissolved Inorganic Nitrogen ...... 6 3.2.2 Ammonia Nitrogen ...... 7 3.3 Microbial contamination - Escherichia coli ...... 9 3.4 Dissolved Organic Carbon ...... 10 3.5 Turbidity ...... 11 3.6 Trend analysis ...... 12 3.7 Ecosystem health...... 13 3.8 Contact recreation...... 16
4 Discussion ...... 18
5 Acknowledgements ...... 20
6 References ...... 20
Appendix 1: Summary of Waimakariri Tributaries water quality 2000-2008 ...... 23
Appendix 2: South Branch before and after the ocean outfall ...... 24
Appendix 3: Cam River before and after the ocean outfall ...... 25
Appendix 4: Photos of Waimakariri Tributaries ...... 26
Appendix 5: Guideline values for water quality determinands used in this study ...... 27
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List of figures Figure 2-1: Map of Waimakariri tributary sampling site ...... 3 Figure 3-1: Distribution of Dissolved Oxygen Saturation (DOSAT%) 2000-2008, note outer edges of box are 20th and 80th percentiles...... 5 Figure 3-2: Distribution of Dissolved Inorganic Nitrogen concentrations 2000-2008...... 6 Figure 3-3: Distribution of Ammonia Nitrogen (mg/L) concentrations 2000-2008 ...... 7 Figure 3-4: Distribution of Dissolved Reactive Phosphorus concentrations 2000-2008...... 8 Figure 3-5: Distribution of Escherichia coli (E. coli) concentrations in the Waimakariri Tributaries 2000-2008...... 9 Figure 3-6: Distribution of Dissolved Organic Carbon (mg/L) concentrations in tributaries of the Waimakariri River 2002 -2008...... 10 Figure 3-7: Distributions of Turbidity concentrations (NTU) in the Waimakariri Tributaries 2000- 2008...... 11 Figure 3-8: Invertebrate community diversity (%) of six tributaries of the Waimakariri River over summer 2008/09...... 14
List of tables Table 2-1: Waimakariri River tributary monitoring sites ...... 2 Table 3-1: Water quality trend analysis 2000-2008; showing Relative Sen Slope Estimator (expressed as % of data median yr)...... 13 Table 3-2: QMCI and Invertebrate Grade over summer 2008/09 ...... 13 Table 3-3: Contact recreational monitoring sites in the Waimakariri catchment ...... 17
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1 Introduction The Waimakariri River has a number of lowland tributaries that enter the river near the sea. These tributaries drain extensive areas of both the Waimakariri District in the north and Christchurch City in the south. Some of the tributaries have historically received a number of industrial and municipal discharges that compromised the water quality of both the tributaries themselves and the lower reaches of the Waimakariri River. Most of these discharges have ceased in recent years through closure of major industries, alternative treatment, or alternative (ocean outfall) disposal options. However, urbanisation of Christchurch suburbs (Belfast, Northwood) and Waimakariri townships (Kaiapoi, Rangiora, and outlying settlements) has the potential to further compromise water quality through the infiltration of contaminants arising from initial land developments and stormwater discharges. Agricultural land use intensification (often associated with irrigation such as the Waimakariri Irrigation Scheme) has also developed rapidly in recent years, and has the potential to further compromise water quality.
The Waimakariri River Regional Plan (WRRP) became operative in 2004 and contains controls on the use and discharge of water, and regimes for monitoring of the Waimakariri River and tributaries. The resulting quarterly monitoring of Waimakariri River tributaries over the past eight years (<32 samples per site) provides a useful data set to summarise the current state, trends, and changes following modification of major discharge activities.
This reports main focus is on reporting the current state, trends and changes in water quality for seven major lowland tributaries of the Waimakariri River; Cam, Cust, Ohoka, Kaiapoi, Courtenay, South Branch/Otukaikino and Styx Rivers. A brief summary on invertebrate health and microbial quality related to contact recreation is also included in this report
2 Methods As part of Environment Canterbury’s (ECan) routine water quality monitoring programme, quarterly water quality data was collected from six rivers in the lower Waimakariri catchment over 2000 to 2008, with an additional site monitored monthly in 2007-2008 (Table 2-1; Figure 3-1). The microbial quality of six tributaries are monitored as part of Environment Canterbury’s contact recreational programme and results are discussed briefly (Table 2-1; Figure 3-1). Standard water quality guidelines where available were used in this report to describe water quality condition (Appendix 5).
Ecosystem health monitoring was also conducted in tributary catchments, although most sites are further upstream than water quality monitoring sites in the Waimakariri catchment (Table 2-1; Figure 3-1). This is due to difficulty in sampling location. Site selection is based on a number of parameters, such as they need to be safely wadeable in order to use the standard ecological and habitat assessment methods. Ecological assessments for five sites monitored by Environment Canterbury in this catchment are discussed in section 3.6. For full methodology see Meredith et al., (2003) and Beech et al., (2007).
In addition to water quality data collected by Environment Canterbury in the Waimariri catchment, water quality and ecosystem health information is also collected for the Styx River and Cam River catchments by the Christchurch District Council, Waimakariri District Council and Styx River Community Group (Golders Associates 2008). However, this report only reports on water quality data and ecosystem health data collected by Environment Canterbury.
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Table 2-1: Waimakariri River tributary monitoring sites
Site ID Sampling River Source Easting Northing SQ30400 Water/Inverterbate Cust River Skewbridge Rd 2479960 5759460 SQ30332 Water Quality Kaiapoi River at Island Rd 2480317 5759031 SQ30343 Water Quality Courtenay River* above the floodgates 2482970 5757580 SQ30369 Water Quality Cam River above Bramleys Rd bge 2480578 5762608 SQ30400 Water Quality Cust River at Skewbridge Road 2479939 5759498 SQ30426 Water Quality Ohoka River at Island Rd 2480220 5759083 SQ30445 Water Quality South Branch Just upstream of Dickeys Rd Bridge 2480460 5752365 SQ32750 Water Quality Styx River Teapes Road 2483978 5751260 SQ00006 Invertebrate Health Cam River Cam Rr-Bramley's Road 2480600 5762500 SQ00423 Invertebrate Health Kaiapoi River Kaiapoi-upper 2474700 5753500 SQ00018 Invertebrate Health Kaiapoi River Kaiapoi River 2476500 5754600 SQ00027 Invertebrate Health Ohoka Ohoka Str-Bradley's Rd 2475300 5760700 SQ00035 Invertebrate Health Styx Styx River-Styx Mill Reserve 2477500 5749300 SQ03436 Contact Recreation Cust River at Recorder 2478600 5760400 SQ30247 Contact Recreation Waimakariri River Mouth 2486040 5757520 SQ30261 Contact Recreation Waimakariri at Boat Ramp 2481300 5754650 SQ30325 Contact Recreation Kaiapoi River at Boat Ramp 2482330 5758150 SQ00451 Contact Recreation Otukaikino Creek at Groynes above Picnic 1 2477900 5750600 SQ02851 Contact Recreation Otukaikino Creek at Groynes below Picnic 1 2478200 5750600 * Sampled monthly in 2007-08
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Environment Ca nterburyTechnical Report Waimakariri tributary report 2008 report tributary Waimakariri
Figure 2-1: Map of Waimakariri tributary sampling site 3
Waimakariri tributary report 2008
2.1 Data analysis Data were analysed using Microsoft Excel 2000, Statistica (V8) and Time Trends (Version 1.10). Microsoft Excel was used for summary data presentation, Statistica was used to provide summary data and box and whisker plots and trend analysis (not flow adjusted) was carried out in Time Trends. Where determinand concentrations were below or above the laboratory detection limit, results were reported as ‘less than’ (i.e. <0.08) or ‘greater than’ (i.e. >2400). These non-detect values were converted to a value equal to half the detection limit (i.e. <0.08 = 0.04) for ‘less than’ results and for ‘greater than’ results the value was converted to a value equal to the detection limit (i.e. >2400 = 2400). See Scarsbrook and McBride (2007) for discussion of appropriate methods when dealing with detection limits.
Water quality data (raw values) are presented in box plots which illustrate how data are distributed around the median value. Box plots portray the median value (50th %ile) as a line, 25th %ile and 75th %ile as the outer edges of a box (note 20%ile and 80%ile are used for dissolved oxygen), 5th %ile and 95th %iles as the outer ends of the whiskers and outlier and extreme values (>95th %iles) as discrete points. These distributions most clearly illustrate any significant differences between representative data sets for different sites and can be related to accepted water quality criteria to highlight issues in this area.
For two tributaries where major municipal sewage discharges have been removed from the streams over the sampling period (Otukaikino/South Branch and Cam River), data were separated into pre and post-discharge removal data sets to illustrate the differences resulting from the discharge removal. No trends were observed at the other monitored sites during the same period as the Otukaikino/South Branch and Cam River. .
2.1 Trend analysis Quarterly water quality data from 6 sites (2000–2008) were analysed for trends in individual parameters using the Seasonal Kendall Test. Trend analysis was conducted in Time Trends (developed by NIWA using Envirolink funding). The Seasonal Kendall Slope Estimator (SKSE) was used to represent the magnitude and direction of trends in water quality data. Values of the SKSE were revitalised by dividing through the raw data median (RSKSE), allowing for a direct comparison between sites. Water quality data was not flow adjusted due to the absence of flow information.
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3 Results A descriptive summary of the water quality data collected over 2000-2008 is included as Appendix 1. Water quality data for physico-chemical parameters; Dissolved Oxygen Saturation and chemical parameters; Dissolved Inorganic Nitrogen, Ammonia Nitrogen, Dissolved Reactive Phosphorous, Escherichia coli, Dissolved Organic Carbon and Turbidity are presented as box and whisker plots (Figures 3-1 – 3-5). Site descriptors ‘before’ and ‘after’ refer to division of data into the time periods before and after removal of municipal sewage discharges.
3.1 Water physico-chemistry Temperature and dissolved oxygen data are daytime spot measurements and as such are not representative of the full diurnal pattern. However, the data do allow comparison of the range of daytime temperatures and dissolved oxygen measured amongst the different river types. Water temperatures were generally cool and ranged between 10 – 19°C amongst the seven Waimakariri river tributaries (Appendix 1). Cool temperatures reflect the predominantly spring-fed source of the tributaries. Dissolved oxygen saturation (DOSAT) concentrations were generally high in the Waimakariri River tributaries (Figure 3-1), with only Courtenay Stream exhibiting most data below the 80 % Saturation guideline value to protect aquatic ecosystems (RMA 1991). Lower DOSAT in Courtenay Stream is likely caused by extensively ponded reaches above the Waimakariri floodgates, which have extensive macrophyte beds and resultant large diurnal variations in dissolved oxygen concentration. The Styx (and Ohoka) River sites also have lower DOSAT than the other sites but to a lesser extent than Courtenay Stream; flows in the lower Styx River are strongly influenced by tide gates at Brooklands. Overall, dissolved oxygen concentrations were high in the majority of tributaries and should not compromise ecological values. No variation in dissolved oxygen saturation before and after sewage discharge removal was observed (Appendix 1).
130
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90
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70
60 DissolvedOxygen (%) Saturation
50
40 Styx R Styx Cust R Ohoka R Kaiapoi R Kaiapoi Cam R After Cam Courtenay R South B After B South Cam R Before South B Before B South Waimakariri Tributaries
Figure 3-1: Distribution of Dissolved Oxygen Saturation (DOSAT%) 2000-2008, note outer edges of box are 20th and 80th percentiles. Red line represents the 80% Saturation guideline for protection of aquatic health (RMA 1991)
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Stream pH values were slightly alkaline, with median values ranging from pH 7.2 and 7.5. The Styx River obtained the lowest recorded pH value of 6.6 and the Courtenay and Kaiapoi Rivers had the most variation in pH values (6.6 – 8.1). Conductivity values in the seven streams were typically low, ranging from 10 – 45 mS/m. The South Branch had the lowest median conductivity value of 9 mS/m and the Courtenay River had the highest median conductivity value of 21 mS/m.
3.2 Nutrients
3.2.1 Dissolved Inorganic Nitrogen Dissolved inorganic nitrogen (DIN) concentrations include all inorganic soluble nitrogen compounds that may be considered plant stimulating nitrogen nutrients. They include nitrate-N, nitrite-N and ammonia-N. Concentrations varied greatly between tributaries and declined after cessation of treated sewage discharges into the South Branch/Otukaikino and Cam River catchment (Figure 3-2 and Appendix 1). Dissolved nitrogen concentrations in Waimakariri tributaries appear to be primarily dominated by nitrate-N, a primary source of nitrate-N is from nitrogen leaching from enriched soils through shallow groundwater and land drainage.
The large differences between the nitrogen concentrations in Waimakariri River tributaries may reflect the extent or area and intensification of leachable soils in the respective tributary catchments (Figure 3-2). The Cust, Ohoka, and Kaiapoi River catchments contain the highest DIN concentrations, the Courtenay River intermediate, and Cam, South Branch/Otukaikino and Styx the lowest. All median DIN concentrations well exceed guidelines for the prevention of nuisance periphyton growths and recreation in all of the waterways monitored (Figure 3-2).
8
7
6
5
4
3
2 Dissolved Inorganic Nitrogen (mg/L) Nitrogen Inorganic Dissolved 1
0 Styx R Styx Cust R Ohoka R Kaiapoi R Kaiapoi Cam R After Cam Courtenay R South B After B South Cam R Before South B Before B South Waimakariri Tributaries
Figure 3-2: Distribution of Dissolved Inorganic Nitrogen concentrations 2000-2008. Red line indicates (0.295 mg/L) guideline value for protection of recreation and aesthetic values (MfE 2000)
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3.2.2 Ammonia Nitrogen
Ammonia nitrogen concentrations were relatively low in all monitored streams and well below ANZECC (2000) toxic thresholds for protection of aquatic ecosystems (1.0mg/L) and below the USEPA (2009) guideline for sensitive waterways protecting early life stages of salmonids (2.9-5.6 mg/L) (Figure 3-3). The Cam and South Brook/Otukaikino data indicated large differences between ‘before’ and ‘after’ sewage removal periods, indicating that the sewage discharges were a major source of ammonia to those streams (Appendix 2). Generally, the data indicate that there are no major sources of ammonia being released in these tributaries and that ammonia toxicity should not be an issue affecting aquatic life.
0.7
0.6
0.5
0.4
0.3
0.2 Ammonia Nitrogen (mg/L) Nitrogen Ammonia
0.1
0.0 Styx R Styx Cust R Ohoka R Kaiapoi R Kaiapoi Cam R After Cam Courtenay R South B After B South Cam R Before South B Before B South Waimakariri Tributaries
Figure 3-3: Distribution of Ammonia Nitrogen (mg/L) concentrations 2000-2008
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3.2.3 Dissolved Reactive Phosphorus
Dissolved Reactive Phosphorus (DRP) concentrations were low in all streams except South Branch/Otukaikino and Cam River prior to cessation of sewage discharges (Figure 3-4). This indicates sewage discharges were highly significant soluble phosphorus sources, and the removal of sewage discharges immediately reduced DRP concentrations in the South Branch/Otukaikino and Cam Rivers to levels similar to other Waimakariri tributaries. Ohoka Stream had the highest ‘non- sewage’ DRP concentrations with the median DRP concentration slightly above the MfE (2000) guideline value of 0.26mg/L for protection of recreation values. All median DRP concentration values were however, within the recommended guideline range (<0.03mg/L) for protection of nuisance periphyton growth (MfE 1992).
Specific patterns of DRP concentrations in the Cam and South Branch/Otukaikino rivers over the period sewage removal are further shown in Appendix 2 and 3. Concentrations show both the high variability of DRP concentrations in the discharge-affected rivers, and the subsequent very low and stable concentrations following sewage discharge removal. A similar pattern is shown for ammonia nitrogen concentrations in the South Branch/Otukaikino (Appendix 2).
0.40
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0.30
0.25
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0.15
0.10
DissolvedPhosphorus Reactive (mg/L) 0.05
0.00 Styx R Styx Cust R Ohoka R Kaiapoi R Kaiapoi Cam R After Cam Courtenay R South B After B South Cam R Before South B Before B South Waimakariri Tributaries
Figure 3-4: Distribution of Dissolved Reactive Phosphorus concentrations 2000-2008. Red line indicates guideline value 0.026mg/L for protection of recreational and aesthetic values (MfE 2000)
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3.3 Microbial contamination - Escherichia coli The concentration of Escherichia coli (E. coli), obtained from water samples provides an indication of faecal contamination and values are often used as an indicator of the potential risk to public health for recreational water use.
Bacterial contamination of Waimakariri lowland tributaries, as indicated by E. coli concentrations, were relatively high (Figure 3-5). E. coli concentrations frequently exceeded 550 MPN/100ml guideline in all tributaries, Ohoka Stream having the highest median concentration. The Cam River was the second most contaminated tributary, with a resulting higher median concentration (550 MPN/100ml) after cessation of the sewage discharge than before removal of the discharge (460 MPN/100ml). By contrast the South Branch/Otukaikino showed a decrease in bacterial contamination following removal of sewage discharge, and thereafter can be considered the least bacterially contaminated Waimakariri River tributary sampled. All other tributaries had median E. coli concentrations at approximately half (260 MPN/100ml) the recommended maximum contact recreation bathing guideline.
2600
2400
2200
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1400
(MPN/100ml) 1200
1000 .coli E 800
600
400
200
0 Styx R Styx Cust R Ohoka R Kaiapoi R Kaiapoi Cam R After Cam Courtenay R South B After B South Cam R Before South B Before B South Waimakariri Tributaries
Figure 3-5: Distribution of Escherichia coli (E. coli) concentrations in the Waimakariri Tributaries 2000-2008. Red line indicates the guideline value of 550 MPN/100ml for protection of recreational bathing (MfE 2000)
Faecal contamination was evident throughout the seven monitored tributaries of the Waimakariri River and the diversion of sewage from the Cam River and South Branch appears to have had little to no effect on E. coli concentrations. Likely sources of faecal contamination include livestock and domestic animals and waterfowl. However, contamination through seepage of human effluent from septic tanks cannot be eliminated.
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3.4 Dissolved Organic Carbon The decomposition of organic matter is the common cause of low river DO concentrations. Organic matter can be either from autotrophic in-river production (plant growth) or inputs (direct or diffuse) of organic compounds. Traditionally, the organic matter decomposition potential of waste water discharges and in-stream was measured as biochemical oxygen demand (BOD) or chemical oxygen demand (COD).
Increasingly, direct BOD and COD measurement in the natural environment is being replaced by measurements of total organic carbon (TOC) and/or dissolved organic carbon (DOC) concentration. This is because of ready availability of rapid analytical tests in most commercial laboratories that return results to much lower detection limits (<0.2 mg/L) than are available for BOD (<2 mg/L) or COD (<9 mg/L). Therefore we include analysis of DOC as part of our water quality program for the Waimakariri tributaries.
Concentrations were relatively low in all tributaries, with median concentrations ranging between 0.6 and 2.3 mg/L (Figure 3-6). A small decrease was observed in the Cam River post outfall, while concentrations remained relatively similar in the South Branch post outfall. The Cust River had the highest median DOC concentrations (2.3 mg/L) and the greatest variability in concentrations. Hayward et al., (2009) recommends a receiving water quality standard of 1 mg/L DOC for all river types. Nearly all sites except South Branch/Otukaikino and Kaiapoi River exceed this guideline value. High DOC values are most likely a result of the high plant biomass and subsequent decomposition commonly occurring in these tributaries.
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2 Dissolved Organic Carbon (mg/L) Carbon Organic Dissolved
1
0 StyxR CustR Ohoka R Ohoka Kaiapoi R Kaiapoi CamRAfter Courtenay R Courtenay SouthB After CamRBefore South B Before B South Waimakariri Tributaries
Figure 3-6: Distribution of Dissolved Organic Carbon (mg/L) concentrations in tributaries of the Waimakariri River 2002 -2008
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3.5 Turbidity
Turbidity measures the degree to which light travelling through water is scattered by suspended particles either organic (algae, plant material) or inorganic (fine silts or clays) and provides an indication of “cloudiness” in water. The greater the amount of suspended material in the water column the higher the turbidity. Turbidity can be caused by soil erosion, waste discharge, urban runoff and algal growth. Over summer turbid waters can become warmer as suspended particles absorb heat from sunlight, causing oxygen levels to fall. This then becomes a problem for aquatic fauna survival due to low dissolved oxygen concentrations as well as reduced habitat and food resources through settling of fine particles.
Turbidity concentrations in the seven monitored tributaries of the Waimakariri River were relatively low (Figure 3-7). A few out lying higher turbidity values are observed, but these are most likely a result rain and or flooding. All median concentration values were below the recommended guideline value of 5.6 NTU (ANZECC 2000), reflecting the typical clear appearance of the stable spring-fed waterways.
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15 Turbidity (NTU) Turbidity 10
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-5 StyxR CustR Ohoka R Ohoka Kaiapoi R Kaiapoi CamRAfter Courtenay R Courtenay SouthB After CamRBefore South B Before B South Waimakariri Tributaries
Figure 3-7: Distributions of Turbidity concentrations (NTU) in the Waimakariri Tributaries 2000-2008. The recommended guideline value is indicated by a red line = 5.6 NTU (ANZECC 2000)
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3.6 Trend analysis For the six tributaries with eight years of data, significant trends were detected in 23 of 66 site and determinand combinations (Table 3-1). Four were positive trends and indicative of declining water quality, while 15 were negative trends and indicative of improving water quality. Dissolved oxygen saturation (DOSAT) showed a positive trend, but is indicative of improving water quality (i.e. higher DOSAT concentrations are desirable); pH showed increasing trends which do not necessarily indicate declining water quality because pH may increase or decrease with declining water quality. Courtenay Stream was excluded from trend analysis as there insufficient water quality data available.
The interpretation of trends from eight years of quarterly water quality data should be considered indicative rather than firm trends. Generally, 10-15 years of quarterly data with flow adjustment would be needed for such trends to be considered to have high statistical ‘rigor’ or ‘power’. They do however give an early indication of issues and priorities for management.
• The Cam River showed six determinands with significantly decreasing trends, and so has generally improved water quality over 2000-2008. These changes largely result from the removal of the South Brook sewage discharge and are strongly represented in the dominant sewage components, DRP and ammonia-N (Wilks 2008). However, it is also of note that all other nitrogen determinands also decreased. Only pH significantly increased, and this is not immediately indicative of either an improvement or degradation in water quality. These results are a vast improvement from a previous report by Main and Lavender (2003), which highlighted a deterioration of water quality in the Cam River.
• The Cust River (Cust Main Drain site) did not show any significant trends and so can be considered to be remaining in a steady water quality state.
• The Ohoka Stream showed six determinands with significant trends. Most showed a negative (decreasing) trend such that water quality was improving over time. Both nitrogen and phosphorus nutrient concentrations decreased and the stream showed increasing water clarity as indicated by decreasing turbidity. Both dissolved oxygen saturation and pH showed positive trends and so were increasing, but these indicate an improvement (DOSAT) or a change that is not immediately positive or negative (pH).
• The Kaiapoi River was the only tributary with a consistent suite of positive (increasing) trends indicative of degradation. Overall water conductivity (an indicator of total dissolved solids concentration) increased, and this is probably largely explained by the similarly increasing concentrations of nitrate+nitrite nitrogen and overall dissolved inorganic nitrogen concentrations. This indicates the concentration of nitrate leaching to the Kaiapoi River is steadily increasing. The Kaiapoi River is also the only tributary with an accompanying increasing concentration of dissolved organic carbon. As with the Cam and Ohoka streams, the Kaiapoi River also exhibited an increasing trend in pH.
• The South Branch/Otukaikino had significant (decreasing) trends in total and dissolved phosphorus, and turbidity. This is again largely explained by the removal of the sewage discharges from the river in 2006, reducing both the concentration and load of phosphorus, and increasing water clarity. The trends in clarity and total phosphorus also reflect the removal of sewage discharge.
• The Styx River had one significant trend, of decreasing ammonia concentrations. The cause of this is not immediately obvious, and there were no other significant trends. Therefore, the Styx River can be considered to be in a relatively steady water quality state.
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Table 3-1: Water quality trend analysis 2000-2008; showing Relative Sen Slope Estimator (expressed as % of data median yr). Only those sites where a Seasonal Kendall test for trend was statistically significant are presented (‘*’ P<0.05; ‘**’ P<0.01; ‘***’P<0.001)
DOSAT Ph COND NH3N NNN TN DIN DRP TP TURB DOC Cam 0.36** -23.636** -6.9** -8.071*** -7.520** -14.375* -12.631** Cust Ohoka 1.213* 0.277*** -8.108* -2.279*** -3.333*** -2.632*** -7.478* Kaiapoi 0.405* 1.537** 2.538** 2.508** 6.25** South Br -9.890* -8.333* -7.333** Styx -8.163*
3.7 Ecosystem health Benthic macroinvertebrates were collected semi-quantitatively using the kick net method with a 500µm mesh net; for full methodology see Meredith et al. (2003). Macroinvertebrate samples were preserved in 70% ethanol and were sorted and identified to the lowest taxonomic level recommended in Stark and Maxted (2007), using keys of Winterbourn et al., (2006). Invertebrate health was assessed using an index of biotic integrity (IBI) (Meredith et. al., 2003) comprised of five composition and tolerance metrics (QMCI, %Eph, %EPT2, %EPT3/%O+%Ch and %EPT3/%M+%Cr). Metrics were compared to the average reference condition for each different source of flow and graded as “very poor”, “poor”, “fair”, “good” and “very good”.
The presence/absence (diversity) of macroinvertebrate species present at any one site provides a good indication of the instream conditions and water quality. Sites on the Cam River, Cust River, Ohoka River, Kaiapoi River and the Styx River have been monitored annually over summer since 1999. The Cust River also underwent an intensive monthly monitoring program over 2008 and one-off sampling of the Otukaikino was undertaken in 2006 (Beech In press).
Recent invertebrate data were available for six of the seven monitored lowland tributaries (Table 3-2; Figure 3-8). Overall, four of the six tributaries monitored were graded as having very poor invertebrate health and two tributaries, the lower Kaiapoi and Styx Rivers as having good or better invertebrate health (Table 3-2). An annual report on Ecosystem Health in Canterbury’s rivers suggests lowland streams invertebrate health is declining (Beech 2007). It is reported that 82% of lowland waterways sampled are graded as very poor (Table 3-2) and that overall the number of sites graded fair or better is declining.
Table 3-2: QMCI and Invertebrate Grade over summer 2008/09
Site ID Site Location QMCI Grading SQ00006 Cam River @ Bramley's Road 2.7 Very Poor SQ30400 Cust River @ Skewbridge Road 4.2 Very Poor SQ00027 Ohoka @ Bradley's Road 3.7 Very Poor SQ00423 Kaiapoi River @ Harpers Road (Upper) 4.3 Very Poor SQ00018 Kaiapoi River @ Haywards Road 6.8 Very Good SQ00035 Styxx River @ Mill Reserve 4.7 Good Lowland Rivers Canterbury Median: 3.6 82% Very Poor
Invertebrate community data represented by invertebrate abundance (%) collected over the 2008-09 summer, suggests the Cam, Cust, Ohoka and upper Kaiapoi are comprised of mainly of pollution- tolerant fauna such as molluscs and worms, whereas the lower Kaiapoi and Styx Rivers invertebrate community fauna has more pollution sensitive fauna such as mayflies (Figure 3-8). Based on QMCI
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results, it is observed that most monitored rivers invertebrate community is stable, expect for the Cam and Ohoka rivers where since summer 2006, the invertebrate community health appears to have be declining (Figure 3-9).
100% Ephemeroptera Trichoptera 80% Crustacea Mollusca 60% Chironomidae Oligochaeta
40% Abundance
20%
0% Cam Cust Ohoka Kaiapoi - Kaiapoi Styx Upper
Figure 3-8: Invertebrate community diversity (%) of six tributaries of the Waimakariri River over summer 2008/09
Waimakariri Tributaries QMCI
8 Cam Riv er
7 Ohoka River
6 Kaiapoi River - low er 5 Styx River
4 QMCI 3
2
1
0
Nov-99 Nov-00 Nov-01 Nov-02 Nov-03 Nov-04 Nov-05 Nov-06 Nov-07 Nov-08 Year
Figure 3-9: Annual invertebrate sampling (November – February 1999-2008) Quantitative Community Invertebrate Index (QMCI) results
14 Environment Canterbury Technical Report Waimakariri tributary report 2008
Cam River Similar to findings from a report on the ecology of the Three Brooks of the Cam River (Golder Associates 2008) an unusual trend (based on QMCI scores) was observed in invertebrate health. The uppermost site on the South Brook showed declining invertebrate health, while the invertebrate health at the downstream Cam River site at Bramley’s Road appeared to be improving. The observed trend is unusual because one would expect the downstream site to be the most degraded and therefore have lower invertebrate health score. The more common pollution-tolerant, sediment-dwelling species such as the mud snail Potomopyrgus antipodarum and oligochaete worms, were overall the most common taxa found at the Three Brooks (South, Middle and North) and the Cam River (Golder Associates 2008).
Invertebrate community in the Cam River followed a similar improving trend as water quality since the commissioning of the ocean outfall in 2006. A notable increase in the abundance of pollution-sensitive mayfly (Ephemeroptera) and caddisfly (Tricoptera) taxa was observed six months after the diversion in 2006 (Figure 3-10), improving the invertebrate score to “Very Good”. However a decline in invertebrate health (QMCI score) was observed last summer (2008), particularly due to the reduced abundance of Ephemeroptera taxa, resulting in a “Very Poor” grade (Figure 3-9). Possible reasons for this may be due to seasonal fluctuation in abundance; change in environment; surrounding land use activity; increased sediment load; decreased water quality or a slight change in sampling location (which was not reported). Continued invertebrate and water quality monitoring is recommended in the Cam River to identify possible sources if degradation continues.
100% Ephemeroptera Trichoptera
80% Crustacea Mollusca Chironomidae 60% Oligochaeta
40% Abundance
20%
0% 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Figure 3-9: Invertebrate community diversity (%) in the Cam River over summers 1999 to 2008
Cust River A detailed report on monthly monitoring conducted on the Cust River is in progress (Beech In press). Briefly, the lowest site monitored on the Cust River at Skewbridge Road (for both water quality and invertebrate health) although having a diverse aquatic life, had a “very poor” invertebrate health grading over summer 2008. The diversity of fauna included moderate abundances of pollution- sensitive mayflies and caddisflies, but more abundant were the less pollution-sensitive mollusca, crustaceans and chironomids. Moderately high abundances of the weed-dwelling crustaceans Paracalliope and ostracoda reflect high macrophyte biomass at the time of sampling. The mixture of pollution-sensitive fauna and less pollution-sensitive invertebrate fauna is representative of the Cust River’s moderate water quality discussed earlier. The Cust River was not able to be included in the time series graph of QMCI as there was not enough data (Figure 3-9). It is important to recognise that
Environment Canterbury Technical Report 15 Waimakariri tributary report 2008
the Cust River undergoes frequent disturbance events by river engineers trying to improve flood management. This places additional stresses on both water quality and invertebrate health, such as substrate displacement and increased suspended sediment.
Ohoka River The Ohoka River followed a similar trend to the Cam River, with invertebrate health improving up until summer 2007 (Figure 3-9). However unlike the Cam River, water quality showed no signs of degradation during the months prior or post sampling events. In 2008 the dominant invertebrate fauna were pollution-tolerant species such as oxyethira, Paracalliope and oligochaeta, with very few pollution-sensitive species such as Deleatidium (mayflies) resulting in a “Very Poor” invertebrate community health grade.
Kaiapoi River In summer 2008 the upper-most site on Kaiapoi River had “Very Poor” invertebrate health, dominated by pollution-tolerant oligochaetes and weed-dwelling Paracalliope. Similar to the Cam River, the further downstream (2.4km) invertebrate health improved with relative abundances of pollution tolerant Ephemeroptera and Tricoptera species increasing, achieving an overall “Very Good” invertebrate health grade.
South Branch/Otukaikino Stream A one-off invertebrate sampling of four sites on the South Branch/Otukaikino Stream was undertaken in 20061. Based on invertebrate data from the Cam River catchment, a similar improvement might have occurred following the diversion of sewage away from the Otukaikino Stream. Four sites monitored on the South Branch/Otukaikino Stream in January 2006 indicate that the stream was in a very unhealthy state; the dominant taxa were pollution-tolerant species such as oligochaetes, crustacea and mollusca, with poor representation by EPT taxa. One might expect there to be an increase in the presence of EPT taxa and an improvement in overall invertebrate health grading following the removal of the sewage discharge from the stream. We therefore recommend collecting invertebrate samples over summer 2009/10 from the South Branch/ Otukaikino Stream to investigate and monitor.
Styx River Invertebrate health at the Styx River site has been highly variable since 1999, with fluctuating invertebrate health grades and QMCI scores (Figure 3-9). The most recent sampling (summer 2008) has shown a dramatic improvement in taxa, scoring a “Good” grade, with more Ephemeroptera species recorded than previous years. This improvement is likely representative of increased community effort to improve water quality and ecosystem functioning by such methods as increasing riparian vegetation along the banks of the Styx River (Golders Associates 2008).
3.8 Contact recreation Environment Canterbury has assessed the microbial quality of popular swimming sites around Canterbury each summer since summer 2002/03 (Stevenson 2008). Sites are graded into five main categories;
• Very Good –satisfactory for swimmers at all times • Good - satisfactory for swimmers most of the time • Fair – generally satisfactory for swimming • Poor – generally not okay for swimming • Very Poor – avoid swimming
Six sites have been monitored in the Waimakariri catchment: Cust and Kaiapoi River, two sites on the Waimakariri River and two sites above and below the groynes in the South Branch/Otukaikino River (Table 3-3 and Figure 2-1). Many of our river sites have moderately good water quality during low flows but bacterial concentrations increase dramatically for a short duration following moderately
1 One off sampling results of South/Branch Otukaikino are not presented in this report, please contact Arthur if further information is required.
16 Environment Canterbury Technical Report Waimakariri tributary report 2008
intense rainfall events. Therefore, some grades are calculated based on the data set excluding rainfall-affected data. Excluding data collected during rainfall conditions allows an assessment of the water quality under conditions that are suitable for swimming (Stevenson 2008).
Monitoring of the Cust Main Drain began in summer 2002/03, but ceased after summer 2005/06 as it was constantly graded as being “Very Poor” and the site was no longer considered a popular swimming location. Summer 2008/09 results showed no changes to the previous years grading categories for the Kaiapoi or Waimakariri Rivers. The Kaiapoi River site continues to have a “Very Poor” grade, reflecting high risk factors and consistently poor water quality. Similarly the two sites monitored on the Otukaikino River have both consistently obtained a “Very Poor” grade.
The grade for the Waimakariri River mouth site has also remained “Very Poor” and only improved to “Poor” with the removal of rain-affected data. However because both of these grades indicate the site is unsuitable for contact recreation the overall grade remains “Very Poor”. The grade for the Waimakariri River at the jet boat ramp has an overall grading of “Poor”, but, when the rain-affected data is removed the grade is “Fair”. This “Fair” grade can be assigned to the site as long as the public is informed of the health risks associated with swimming at the site soon after rainfall.
Table 3-3: Contact recreational monitoring sites in the Waimakariri catchment
Site Source Grading 08/09 SQ03436 Cust River Main Drain Very Poor# SQ30325 Kaiapoi River @ Boat Ramp Very Poor SQ30247 Waimakariri River Mouth Very Poor SQ30261 Waimakariri @ Boat Ramp *Fair SQ00451 Otukaikino Ck at Groynes above Picnic 1 Very Poor SQ02851 Otukaikino Ck at Groynes below Picnic 1 Very Poor * Grading after rain affected data was removed # Last sampled in 2005/06
Environment Canterbury Technical Report 17 Waimakariri tributary report 2008
4 Discussion The removal of municipal sewage discharges from the Cam River and South Branch/Otukaikino has resulted in significant improvements in water quality, particularly in relation to phosphorus concentrations and therefore loads. Removal of discharge from the Cam River and South Branch/Otukaikino, resulted in soluble phosphorus concentrations that were very similar to other tributaries and variability was markedly reduced. The improvement in water quality in the Cam River was mirrored closely by the recovery of the invertebrate community, with an increase in abundance of pollution-sensitive fauna. However, although there have been significant water quality improvements, and invertebrate health improvements, instream biodiversity is still poor. This maybe due to a lag period before a positive response is detected in the invertebrate fauna. Therefore it is recommended that ecosystem monitoring be continued in the Cam River and established on the South Branch/Otukaikino.
Results indicate that the initiatives of both Waimakariri District Council and Christchurch City Council, have yielded significant water quality benefits from the investments in alternative discharge methods. The South Branch/Otukaikino is now considered to have the highest water quality of the lowland Waimakariri tributaries. Despite its “Very Poor” contact recreation grading, the inflowing South Branch/Otukaikino is increasingly used for recreational bathing and the removal of treated sewage discharge has resulted in a reduced bacterial risk to recreational uses. There are also increasing expectations from the local community to improve values and uses of the Cam River, such as improving environmental health, which will benefit from the removal of sewage contaminants and associated risks.
Concentrations of faecal indicator bacteria in Waimakariri tributary streams is of some concern as E. coli counts regularly exceed the contact recreation guideline of 550 MPN/100ml, resulting in very poor contact recreational grades. The sources are likely to be a mixture of natural (wildlife), agricultural (livestock), and discharges, but exclusion of livestock from stream banks and springheads hold most promise for reduced concentrations.
The biggest variation in water quality between the various tributaries was in dissolved nitrogen concentrations, which was dominated by nitrate+nitrite-N. Variability to some extent reflects variations in the positions of the tributaries in the plains landscape, hydrology and source of groundwater recharge. The relatively low DIN concentrations of the South Branch and Styx Rivers (~0.5 mg/L) reflects the predominance of recharge from water lost from the Waimakariri, and re-arising in tributary springs and seeps. Likewise, lower DIN concentrations in the Cam River may reflect groundwater recharge from the adjacent Ashley River, rather than from extensive plains aquifers. This is further illustrated by differences observed between the South Brook, Middle Brook and North Brook and their respective increasing proximity to the Ashley River (Golder Associates 2008). In contrast, the Cust, Ohoka and Kaiapoi interact with more extensive areas of plains aquifers and receive little recharge from proximity to major hill or alpine rivers.
Of particular interest are the trends of decreasing nitrogen concentrations in the Ohoka Stream, increasing nitrogen concentrations in the Kaiapoi River, and a lack of trend for nitrogen concentrations in the Cust River. These differing trends could indicate responses to variable degrees of land use intensification in parts of the Waimakariri District, or of variable effects of different types of intensification (irrigation, fertiliser use, and/or stock density) or hydrology.
Nitrogen increases in the Kaiapoi River could indicate effects of increasing intensification in the Kaiapoi River catchment, including areas from Eyreton, Swannanoa, and West Eyreton towards Oxford. The finding of increasing dissolved organic carbon in the Kaiapoi River could also indicate increasing water logging or irrigation leaching of sub-catchment soils. Increased nitrogen concentrations could be associated with increased land conversion to intensive uses such as dairy farming, and increased pasture irrigation, both from groundwater and Waimakariri Irrigation scheme sources. Conversely, results for Ohoka Stream could indicate reduced agricultural development in the Kaiapoi/Ohoka catchment following decommissioning of several dairy farms and other intensive land uses in favour of increasing lifestyle block residential development.
18 Environment Canterbury Technical Report Waimakariri tributary report 2008
Although water quality results suggest no significant trends in the Cust catchment, dissolved nitrogen concentrations are high (median 4.4mg/L) and has overall poor-moderate water quality. Ecosystem health monitoring results suggest the Cust River instream biodiversity is degraded. This observed poor invertebrate health may be representative of frequent river engineering work that takes place along the Cust River to help manage and maintain flood protection.
The Courtenay Stream had intermediate nitrogen concentrations. Water which was formerly thought to be primarily sourced from Waimakariri River water percolating under its stopbanks, is now thought to also be influenced by more of a plains groundwater source predominance due to the moderately high nitrogen concentrations. Unfortunately no estimate of trends can be obtained from the short data set for Courtenay Stream.
While the Cust and Styx Rivers water quality showed little improvement, it is positive that water quality is remaining in a steady state and showed no signs of further degradation. A notable difference in invertebrate fauna was observed, and this is primarily attributed to community effort in improving the Styx River environment. The Ohoka River showed improved water quality, with both nutrient concentrations and water clarity improving. The Kaiapoi River was the only monitored tributary with declining water quality, and this is most likely representative of intensified land use pressures in the catchment.
Environment Canterbury’s water quality monitoring programme is particularly useful for detecting/monitoring effects of agriculture, however it has some limitations; the ability to detect effects from urbanisation is difficult and unlikely as this is most likely reflected in increasing metals, which are not part of regular parameters analysed. However, other monitoring programs undertaken by the Christchurch City Council and the Waimakariri District Council are focused on the effects on water quality from urbanisation pressures such as storm water and sediment runoff.
To conclude, cessation of waste water discharge in 2005 and the initiatives to improve discharge methods of both Waimakariri District Council and Christchurch City Council, have yielded significant water quality improvements in the Cam River and South Branch/Otukaikino. Other monitored tributaries water quality shows improvement or remaining in a steady state, with the exception of the Kaiapoi River which appears to be declining. High nitrogen concentrations are an ongoing issue in many lowland streams in Canterbury, primarily due to inputs from surrounding land use activities. Therefore it is recommended that monitoring of these tributaries (both water quality and ecosystem health) is continued, and an investigation into the declining water quality in the Kaiapoi River is recommended.
Environment Canterbury Technical Report 19 Waimakariri tributary report 2008
5 Acknowledgements We wish to thank those staff involved in collecting water quality and invertebrate samples at Environment Canterbury and analyses of water quality samples by the laboratory staff at Environment Canterbury. We also wish to thank Greg Burrell from Golders Associates for reviewing and providing constructive comment to the report.
6 References
Australian and New Zealand Environment and Conservation Council (ANZECC), 2000. Australian New Zealand guidelines for fresh and marine water quality. Australian and New Zealand Environment and Conservation Council, Agriculture and Resource Management Council of Australia and New Zealand. Beech, M., in press Ecosystem Health: Cust River. Environment Canterbury.
Beech., M. A. 2007. Ecosystem health monitoring programme November-December 2006 and site specific habitat trend analysis 2000 – 2006. Study of Selwyn River at Coes Ford.
Beech., M.A. 2009. Ecosystem health monitoring programme November-December 2008. Environment Canterbury.
Golders Associates (2008). Integrated Monitoring Strategy for the Styx. Submitted to: Christchurch City Council and Environment Canterbury.
Hayward, S. A., Meredith, A. S. & Stevenson, M. (2009). Review of proposed NRRP water quality objectives and standards for rivers and lakes in the Canterbury region. Environment Canterbury, R09/19 ISBN 978-1-86937-932-2.
Main, M., R., and Lavender, R., 2003. The Cam River: an assessment of water quality and ecosystem health monitoring, 1992-2001. Environment Canterbury Report No. R03/17; ISBN 1-86937- 495-9.
Meredith, A. S., Cottam, D., Anthony, M. and Lavender, R. 2003. Ecosystem health of Canterbury rivers: development and implementation of biotic and habitat assessment methods 1999/2000. Environment Canterbury technical report R03/03.
MfE (Ministry for the Environment). 1992. Water Quality Guidelines No.1. Guidelines for the control of undesirable biological growths in water. Ministry for the Environment, Wellington.
MfE (Ministry for the Environment). 2002. Microbiological Water Quality Guidelines for Marine and Fresh Water Recreational Areas. ME No. 447. Ministry for the Environment, Wellington.
MfE (Ministry for the Environment). 2003. Microbiological Water Quality Guidelines for Marine and Fresh Water Recreational Areas. Ministry for the Environment, Wellington.
RMA, 1991: Resource Management Act 1991.
Scarsbrook, M.R & McBride, G.B. 2007. Best practice guidelines for the statistical analysis of freshwater quality data (Version 1). Prepared for: Ministry for the Environment. NIWA Client Report: HAM2007-088. pg 18-19.
Stark, J.D., and Maxted, J.R., 2007. A user guide for the Macroinvertebrate Community Index. Cawthron Report No 116. Prepared for: Ministry for the Environment.
20 Environment Canterbury Technical Report Waimakariri tributary report 2008
Stevenson, M., 2008. Freshwater contact recreational monitoring programme Canterbury region: Annual summary report 2008/09. Environment Canterbury.
Unites States Environmental Protection Agency (USEPA) (2009). Draft 2009 Update Aquatic life ambient water quality criteria for Ammonia - Freshwater.
Wilks, T.C. 2008. Summary Report: Water Quality Investigation of the Cam River May 2007 – June 2008. Unpublished. Environment Canterbury.
Winterbourn, M.J., Gregson, K.L.D., and Dolphin, C.H., 2006. Guide to the Aquatic Insects of New Zealand 4th Edition. Bulletin of the Entomological Society of New Zealand.
Environment Canterbury Technical Report 21 Waimakariri tributary report 2008
22 Environment Canterbury Technical Report
Environment CanterburyTechnical Report Appendix 1: Summary of Waimakariri Tributaries water quality 2000-2008 TEMP DO DOSAT Ph COND NH3N NNN TN DIN DRP TP SS TURB DOC ECOLI °C mg/L % mS/m @25°C mg/L mg/L mg/L mg/L mg/L mg/L mg/L NTU mg/L MPN/100ml SQ30369 Cam River Before Outfall Pipe (February 2000 - February 2006) No Samples 25 25 25 25 25 25 25 25 25 25 25 11 25 14 21 Minimum 10 9 82 7.2 10 0.003 0.590 0.750 0.605 0.110 0.140 7 3 1.1 150 Median 13 10 99 7.4 13 0.180 1.000 1.500 1.230 0.180 0.250 8 4 1.3 460 Maximum 16 13 123 7.7 14 0.640 2.400 2.800 2.620 0.360 0.400 21 12 2.2 1100 SQ30369 Cam River After Outfall Pipe (May 2006 - August 2008) No Samples 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 Minimum 10 10 90 7.3 11 0.009 0.510 0.590 0.525 0.008 0.014 4 2 0.9 260 Median 13 10 98 7.6 12 0.019 0.695 0.890 0.716 0.011 0.024 5 3 1.1 550 Maximum 15 12 111 7.7 17 0.045 1.900 2.100 1.945 0.036 0.073 10 12 3.6 2400 SQ30400 Cust River No Samples 35 35 35 35 35 35 35 35 35 35 35 19 35 24 31
Minimum 7 9 88 7.2 16 0.003 2.500 3.000 2.583 0.010 0.018 1 0 1.6 30 2008 report tributary Waimakariri Median 11 11 103 7.7 18 0.021 4.400 4.700 4.412 0.023 0.033 2 2 2.4 260 Maximum 19 14 120 7.9 21 0.088 6.900 6.900 6.929 0.073 0.200 15 22 7.8 1600 SQ30426 Ohoka River No Samples 35 35 35 35 35 35 35 35 35 35 35 21 35 24 31 Minimum 8 7 70 7.1 15 0.003 2.800 2.900 2.821 0.015 0.021 2 1 0.8 180
Median 11 10 86 7.2 19 0.037 4.300 4.500 4.332 0.030 0.045 5 2 1.3 630 Maximum 17 12 112 7.5 22 0.220 5.600 7.000 5.651 0.078 0.210 21 42 5.6 2400 SQ30332 Kaiapoi River
No Samples 35 34 35 35 35 35 35 35 35 35 20 35 24 31 Minimum 9 8 82 7.2 14 0.003 2.700 2.700 2.785 0.006 0.008 1 0 0.5 42 Median 12 11 99 7.4 16 0.021 3.900 4.000 3.906 0.012 0.018 3 1 0.8 290 Maximum 17 14 125 8.1 20 0.110 5.000 5.900 5.032 0.037 0.160 16 7 3.1 1500 SQ30343 Courtenay River No Samples 12 12 12 12 12 12 12 12 12 12 12 12 12 12 Minimum 9 4 45 6.9 18 0.050 0.460 0.940 0.546 0.004 0.004 1 0.9 66 Median 13 8 80 7.6 21 0.087 2.800 3.000 2.880 0.017 0.031 2 1.2 275 Maximum 18 10 96 8.1 45 0.270 3.100 3.500 3.300 0.190 0.220 13 5.2 2400
SQ30445 South Branch/Otukaikino River Before Diversion (February 2000 - February 2006) No Samples 25 25 25 25 25 25 25 25 25 25 25 10 25 14 21 Minimum 9 9 82 7.2 8 0.016 0.210 0.330 0.310 0.029 0.038 2 0 0.4 110 Median 12 10 91 7.3 10 0.220 0.400 0.660 0.620 0.100 0.130 3 1 0.6 260 Maximum 16 12 106 7.7 15 0.430 0.540 1.100 0.860 0.170 0.180 7 2 1.1 820 SQ30445 South Branch/Otukaikino River After Diversion (May 2006 - August 2008) No Samples 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 Minimum 10 8 83 7.2 9 0.017 0.300 0.310 0.320 0.015 0.024 1 0 0.5 82 Median 12 10 90 7.3 9 0.021 0.435 0.565 0.455 0.022 0.037 2 1 0.7 185 Maximum 14 12 108 7.5 12 0.089 0.980 1.000 1.013 0.052 0.060 4 2 1.5 730 SQ32750 Styx River No Samples 35 34 35 35 35 35 35 35 35 35 35 21 35 24 31 Minimum 10 7 63 6.6 10 0.006 0.340 0.410 0.389 0.015 0.024 0 1 0.7 110 Median 13 9 83 7.5 13 0.049 0.520 0.610 0.564 0.022 0.041 3 2 1.1 250 Maximum 17 12 110 7.9 21 0.100 1.100 1.400 1.181 0.055 0.085 36 6 4.9 2400 23
Waimakariri tributary report 2008
Appendix 2: South Branch before and after the ocean outfall
South Branch SQ30445
0.18 0.16 0.14 0.12 0.1 0.08
DRP (mg/L) DRP 0.06 0.04 0.02 0
Feb-00 Aug-00 Feb-01 Aug-01 Feb-02 Aug-02 Feb-03 Aug-03 Feb-04 Aug-04 Feb-05 Aug-05 Feb-06 Aug-06 Feb-07 Aug-07 Feb-08 Aug-08 Date
Dissolved Reactive Phosphorus concentrations in the South Branch/Otukaikino (SQ30369) before (prior August 2006) and after commissioning of diversion to Bromley sewage network.
South Branch SQ30445
0.5 0.45 0.4 0.35 0.3 0.25 0.2 NH3N (mg/L)NH3N 0.15 0.1 0.05 0
Feb-00 Aug-00 Feb-01 Aug-01 Feb-02 Aug-02 Feb-03 Aug-03 Feb-04 Aug-04 Feb-05 Aug-05 Feb-06 Aug-06 Feb-07 Aug-07 Feb-08 Aug-08 Date
Ammonia Nitrogen concentrations in the South Branch/Otukaikino (SQ30369) before (prior August 2006) and after commissioning of diversion to Bromley sewage network.
24 Environment Canterbury Technical Report Waimakariri tributary report 2008
Appendix 3: Cam River before and after the ocean outfall
Cam River below Bramleys Road bridge
0.4
0.35
0.3
0.25
0.2
DRP (mg/L) 0.15
0.1
0.05
0
Feb-00 Jun-00 Oct-00 Feb-01 Jun-01 Oct-01 Feb-02 Jun-02 Oct-02 Feb-03 Jun-03 Oct-03 Feb-04 Jun-04 Oct-04 Feb-05 Jun-05 Oct-05 Feb-06 Jun-06 Oct-06 Feb-07 Jun-07 Oct-07 Feb-08 Jun-08 Date
Dissolved Reactive Phosphorus concentrations in Cam River below Bramleys Road bridge (SQ30369) before (prior February 2006) commissioning of ocean outfall and after (post May 2006).
Environment Canterbury Technical Report 25 Waimakariri tributary report 2008
Appendix 4: Photos of Waimakariri Tributaries
Cam River @ Bramleys Road (in flood) Cust River @ Skewbridge Road (in flood)
Ohoka River @ Island Road Kaiapoi River @ Island Road
South Branch/Otukaikino @ Dickeys Road Styx River upstream of Teapes Bridge
26 Environment Canterbury Technical Report Waimakariri tributary report 2008
Appendix 5: Guideline values for water quality determinands used in this study
Determinand Value & relevance Standards & guidelines Reference
Bolded font indicates guideline values used in this report. Dissolved oxygen Aquatic ecosystems – requirement 90% Hayward et al (2009) % saturation for aquatic life Aquatic ecosystems – thermal < 20°C Temperature tolerance of aquatic organisms < 25°C RMA (1991)
Turbidity Aquatic ecosystems 5.6 NTU ANZECC (2000)
Dissolved Organic Aquatic ecosystems 1.0 mg/L Hayward et al (2009) Carbon
Nitrate-nitrite Aquatic ecosystems – nutrient for < 0.444 mg/L 1 nitrogen (NOx-N) weed growth, toxic at higher ANZECC (2000) < 7.2 mg/L concentrations Ammonia-nitrogen Aquatic ecosystems – nutrient for < 0.021 mg/L 1 (NH3-N) weed growth, toxic at higher < 0.9 mg/L ANZECC (2000) concentrations 1.0 mg/L (from formula) Dissolved inorganic Recreational/Aesthetic (20 day <0.295 mg/L MFE (2000) nitrogen (DIN) accrual periods)
Nuisance periphyton growth 0.015-0.030 mg/L MfE (1992) Dissolved reactive
phosphorus (DRP) Aquatic ecosystems
-Recreational/Aesthetic (20 day <0.026 mg/L MfE (2000) accrual periods) E. coli Recreational – safe for contact recreation < 550 MPN/100mL MfE (2003) (single sample)
< 126 cfu/100mL < 410 cfu/100mL MfE (2002) (median values) 1 The ANZECC (2000) guidelines provide trigger values for different river types and different levels of ecosystem protection. The trigger values presented here relate to NZ lowland rivers and slightly to moderately disturbed systems, or a 95% level of protection.
Environment Canterbury Technical Report 27