Te Waihora/Lake Ellesmere Catchment Flow Review, Ecological Values and Flow Recommendations at Minimum Flow Sites.
Report No. R12/123 ISBN 978-1-927284-37-7 (print) 978-1-927284-38-4 (web) 978-1-927284-39-1 (electronic)
Report prepared for Environment Canterbury by Golder Associates
June 2012
Report No. R12/123 ISBN 978-1-927284-37-7 (print) 978-1-927284-38-4 (web) 978-1-927284-39-1 (electronic)
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
This report represents advice to Environment Canterbury and any views, conclusions or recommendations do not represent Council policy. The information in this report, together with any other information, may be used by the Council to formulate resource management policies, e.g., in the preparation or review of regional plans.
June 2012
TE WAIHORA/LAKE ELLESMERE CATHMENT FLOW REVIEW
Ecological Values and Flow Recommendations at Minimum Flow Sites
Submitted to: Canterbury Regional Council P O Box 345 Christchurch 8140
Report Number. 0978110119-002-R-Rev0 Distribution:
REPORT Canterbury Regional Council
TE WAIHORA CATCHMENT ECOLOGICAL FLOWS
Table of Contents
1.0 INTRODUCTION ...... 1
1.1 Background ...... 1
1.2 Report Scope ...... 1
2.0 ECOLOGICAL DESCRIPTIONS OF MINIMUM FLOW SITES ...... 3
2.1 Methods...... 3
2.2 Ecological Descriptions ...... 4
3.0 ECOLOGICAL MINIMUM FLOW RECOMMENDATIONS ...... 9
3.1 Introduction ...... 9
3.2 Recommended Minimum Flows ...... 9
3.3 Ecological State and Minimum Flows ...... 12
3.4 Priority Sites...... 12
4.0 ADEQUACY OF EXISTING MINIMUM FLOW SITES ...... 13
4.1 Background ...... 13
4.2 Geographic Coverage ...... 14
4.3 Reduction of Minimum Flow Sites ...... 16
5.0 SUMMARY ...... 17
6.0 REFERENCES ...... 18
TABLES Table 1: Summary descriptions of ecological values at minimum flow sites and overall stream catchments...... 5 Table 2: Current and recommended minimum flows for existing minimum flow sites...... 11 Table 3: Sites with permanent flow recorders and sites with flows correlated to recorder site flows. Adapted from Clark (2011)...... 15
FIGURES Figure 1: Minimum flow sites in the Te Waihora catchment...... 2 Figure 2: Relationship between current and recommended minimum flows. Data points below the green diagonal line have current minimum flows that are lower than recommended for protection of ecological values...... 10 Figure 3: Current minimum flows expressed as a percentage of 7DMALF. Minimum flows below the dashed orange line are a moderate priority for increasing minimum flows, while bars falling below the solid red line indicate high priority sites. The left orange dashed line indicates flow-sensitive sites, while the lower dashed line indicates less flow-sensitive sites...... 13 Figure 4: Schematic showing minimum flow sites on smaller tributaries (Site "A") and different rivers altogether (Site "B") from the river where the flow recorder is located. Abstraction could result in adverse effects on river flow at these minimum flow sites if their flows are only monitored at the flow recorder site...... 16
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APPENDICES APPENDIX A Report Limitations
APPENDIX B Technical Panel Value Scores
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TE WAIHORA CATCHMENT ECOLOGICAL FLOWS
1.0 INTRODUCTION 1.1 Background Canterbury Regional Council (CRC) is reviewing minimum flows and allocation limits for rivers in the Te Waihora/Lake Ellesmere catchment. A minimum flow is the flow below which water abstraction from a river or hydraulically connected groundwater must cease, while allocation refers to the total volume or rate of water allocated for abstraction in a catchment. Existing minimum flows in the catchment were historically set via consent processes with little consideration of the cumulative effects of abstraction. The current flow review process is considering cumulative effects by modelling impacts of groundwater and surface water abstraction together. Figure 1 shows the location of existing minimum flow sites in the Te Waihora catchment. Golder Associates (NZ) Limited (Golder) has been providing ecological input into the flow review for CRC, including a summary of aquatic ecological values and flow recommendations (Golder 2011). The Golder (2011) report provided general minimum flow recommendations that could be applied to rivers throughout the catchment. Minimum flow recommendations were indexed to seven day mean annual low flow (7DMALF1), a common low flow statistic. The proportion of 7DMALF recommended as a minimum flow varied amongst stream types, with larger spring-fed streams (7DMALF>300 L/s) having a lower proportion of 7DMALF recommended as the minimum flow than either hill-fed streams or smaller spring-fed streams, which were considered more sensitive to low flows (Golder 2011). More recently, CRC hydrologists have used regression analyses between minimum flow sites with flow recorders and sites that lack recorders to estimate 7DMALF for the sites without recorders (Clark 2011).
1.2 Report Scope This report2 covers the following tasks assigned by CRC: Summarise ecological values present at each minimum flow site. Provide specific minimum flow recommendations for existing minimum flow sites. Discuss the adequacy of existing minimum flow sites to protect aquatic ecology, and whether the number of existing minimum flow sites can be reduced. A separate report (Golder 2012) describes the effect of different flow management scenarios on aquatic ecological values present at minimum flow sites in the Te Waihora/Lake Ellesmere catchment.
1 Flows were naturalised by CRC prior to calculating 7DMALF. The naturalising process involved adding in known water takes to the flow record. 2 This report is subject to the limitations in Appendix A.
June 2012 Report No. 0978110119-002-R-Rev0 1
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0 0 s 7 7 i 2. Minimum flow sites sourced from Ecan. 5 5 h t 2. Schematic only, not to be interpreted as an engineering design or construction drawing. n i 3. Drawn by: NP. Reviewed by: HG. Coordinate System: GD 1949 New Zealand Map Grid d e n i a t 2400000 2420000 2440000 2460000 2480000 n o c n o i t a TITLE JUNE 2012
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2.0 ECOLOGICAL DESCRIPTIONS OF MINIMUM FLOW SITES 2.1 Methods This section of the report draws on existing sources of information on water quality, periphyton (algae), macrophytes (aquatic plants), invertebrates, and fish to summarise ecological values at each existing minimum flow site. All of the various data sources and values identified for each minimum flow site were tabulated in a spreadsheet. The final output was a concise ecological description of each site, which is provided in the following section of this report. The spreadsheet containing all of the underlying ecological data was provided separately to CRC. Key sources of information included CRC water quality and biological monitoring (invertebrates, habitat and periphyton cover), the New Zealand Freshwater Fish Database (NZFFD), CRC technical reports, and evidence produced for the Central Plains Water hearing and the Rakaia-Selwyn and Selwyn-Waimakariri groundwater zone hearings. The names, locations, flow statistics and minimum flows (where one exists) for each site were provided by CRC. Another useful source of general ecological information drawn upon was a series of unpublished draft CRC reports produced as part of an initial review of minimum flows for rivers in the catchment. The review used an Technical Panel assembled specifically for the catchment flow review process, with expertise in the areas of trout, native fish, general aquatic habitat, general amenity, indigenous vegetation, and Maori values. The Technical Panel visited streams during low flow conditions in summer 2003 and 2005, and ranked each waterway according to the values it supported. Each panellist then used their professional judgement to recommend the minimum flow required to sustain a given instream value. We converted panellist “value” scores to numbers from 1 to 5, with a “low” score receiving a 1, “moderate” receiving a 3, and “high” value receiving a score of 5 (see Appendix B). Occasionally no formal descriptive category was given, whereupon brief comments have been included. CRC requested that streams be classified as to whether they were natural waterways or managed as drains. In the summary spreadsheet channel form was described based on aerial photography, and descriptions of the various streams found throughout the literature. It should be noted that while a stream may be described as having a natural form, this description simply denotes that the channel does not follow paddock boundaries, or roads, rather it wanders across such features. The description does not imply that the stream follows its natural course and is therefore unaltered by surrounding land-use activities. Similarly, management of the channel, either as a drain or not, was compiled based on descriptions in the literature and drainage map layers provided by the Selwyn District Council (SDC) and Christchurch City Council (CCC). It should be noted that sites labelled as a managed drain may be subject to aquatic plant clearance with variable periodicity; often on a ‘when needed’ basis. Sites not included in the drainage management network of the relevant council may also be periodically cleaned by local landowners or other authorities. Fish community information was taken primarily from the NZFFD. Fish were recorded as being absent (0), present (1), or no records exist for the site (3). Records were only included within the information for each site if they occurred within 2 km. Further fish data was added from the general literature. Invertebrate information was compiled primarily from CRC monitoring records. Actual values shown in the spreadsheet are means of all available records for each site. Only data collected during the last ten years and within 2 km along the stream are included. Further information was gathered from the general literature. Trout spawning values were taken from Taylor & Good (2006) and represent a thorough assessment of the overall health of each waterway. In particular, brown trout require clean, cold water and gravels free of fine sediments to spawn, as well as physical access to any reach of the stream. Taylor & Good (2006) provide numbers of redds (spawning “nests”) and spawning fish, but only qualitative descriptions of spawning value. General habitat notes have also been included for each stream and site. Additional information was provided by a survey and GIS layer of salmonid distributions and habitats in the Canterbury region by Langlands & Elley (2000).
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Water quality data has primarily been compiled from CRC records and consists of statistics derived from all the data available from each site. This information was augmented from the general literature and Golder (2011). Section 6.0 includes a list of literature information sources used in compiling ecological values at each minimum flow site. Catchment-scale values (i.e., values present within a stream, but not specifically found at the minimum flow site) listed in the spreadsheet combine the most prominent ecological features of each stream into a broad overview based on the literature and various data sources described above.
2.2 Ecological Descriptions Table 1 below summarises ecological values at each minimum flow site and provides an overall description of ecological values present in the wider catchment for each waterway. Despite widespread habitat degradation and frequently elevated nutrient concentrations, most minimum flow sites support a range of native fish and trout, and may be considered to have at least moderate ecological value. Sites with high ecological value include Prices Stream and Kaituna River, which drain Banks Peninsula and are characterised by stony beds, healthy invertebrate fauna, and the presence of threatened native fish such as longfin eel, inanga and lamprey. The hill-fed Selwyn River and its tributaries, the Hawkins and Hororata Rivers are also considered to have high ecological value, again due to the predominantly silt-free stony bed sediments, healthy invertebrate populations, and the presence of acutely threatened Canterbury mudfish populations in the upper catchment. Harts Creek is one of the few spring-fed lowland streams that is considered to have high ecological values, as it supports brown trout spawning and adult trout habitat, plus has a diverse native fish fauna, and has received substantial riparian enhancement and protection. Minimum flow sites with relatively low ecological value include Baileys Stream, Snake Creek, Miles Drain, the Irwell River, and Doyleston Drain. All of these waterways have significant sedimentation and many have un- naturally low flows. Observations of silt-free gravels and brown trout spawning in many of these tributaries in the 1980s suggest that these waterways have previously been capable of supporting higher ecological values. Some larger rivers, such as the L2 and Halswell Rivers, have multiple minimum flow sites along their length and ecological condition and value varies from site to site. For these waterways, minimum flows at degraded or lower value sites will need to be set to protect values present at less degraded and more highly valued sites.
It should be noted that at some locations the conclusions of the technical panel may contradict other information presented and the overall site conclusion. This occurs because the technical panel assessments were made in the absence of any formal specific ecological data and were based on a single visual inspection of the site. Therefore, although taken into account in this summary the findings of the technical panel may not be in accordance with the overall assessment.
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Table 1: Summary descriptions of ecological values at minimum flow sites and overall stream catchments.
Site Easting Northing Minimum flow site ecological values Catchment scale values
High ecological values. This is a natural river with large areas of native vegetation on steep hill country in the catchment. The river is subject to occasional destructive flooding. Includes moderate trout spawning values. Technical panel assessments suggest moderate values for indigenous vegetation and native fish, low values for The Kaituna River catchment has high ecological values due to the Kaituna River at 2485535 5719426 general amenity and trout, but moderate to high values for natural character, Mahinga Kai and Mauri. Overall aquatic occurrence of clean water invertebrate communities and threatened Kaituna Valley Rd habitat value is low to moderate. According to the NZFFD seven species of fish are present including threatened fish in the upper two thirds of the catchment. longfin eel, inanga and lamprey. Adult trout are present. Nitrogen and phosphorus levels are low and invertebrate communities are indicative of excellent water quality.
High ecological values. This is a natural river with large areas of native vegetation on steep hill country in the catchment. Moderate brown trout spawning values, with spawning observed in the mid-reaches of the river. Technical panel assessments suggest that trout and Mauri values are low, indigenous vegetation values are low- Prices Stream has good ecological values due to the occurrence of Prices Stream at 2486360 5714937 moderate and native fish, natural character and general amenity are moderate. Mahinga Kai values are high and clean water invertebrate communities and threatened fish. However, Prices Valley Rd overall aquatic habitat value is low. Based on NZFFD records four fish species are present and include threatened there is sparse information about water quality and fish communities inanga. Goldfish are also present. There is limited water quality data available but invertebrate communities are indicative of good water quality. High ecological values. This is a natural waterway, but with some stock access. Trout spawning values are unknown. Hawkins River at High ecological values. The Hawkins River is a major tributary of the According to the NZFFD six fish species are present and include the threatened longfin eel. Brown trout and brook Willows- Dalethorpe 2416004 5758085 Selwyn River. The lower reaches of the stream dry during summer, char are also present. Water quality data indicate that nitrogen levels are elevated and invertebrate communities are Rd particularly below Deans Rd. indicative of good water quality. High ecological values. This a natural waterway with unknown trout spawning values. Invertebrate communities are Hororata River at High ecological values due to the presence of Canterbury mudfish, indicative of poor water quality but according to the NZFFD five fish species are present and include the threatened Haldon water race 2429520 5736340 which occur in adjacent wetlands and ponds. The stream is known to longfin eel. Acutely threatened Canterbury mudfish are present in adjacent wetlands and ponds. Brown trout are bridge dry in the middle reaches. present. High ecological values. The upper Selwyn River is a natural waterway which retains permanent flow downstream to The upper Selwyn River has high ecological values due to the Scotts Rd. Trout spawning values are high although the adult population has declined dramatically in recent Selwyn River at occurrence of a number of threatened fish species, high trout habitat 2420400 5749000 decades. According to the NZFFD four fish species are present and include threatened longfin eel. The acutely Whitecliffs potential and clean water invertebrate communities. Canterbury threatened Canterbury mudfish is known to occur in wetlands and tributaries. Brown trout are present. Water is cool, mudfish are present in the catchment. oxygenated and has low nutrient levels. Invertebrate communities are indicative of excellent water quality. High ecological values. The lower Selwyn River is partially channelised and contained within flood embankments. The lower Selwyn River downstream of the intermittent reach has high Selwyn River at Trout spawning values are high despite a significant decline in the fishery since the mid 1980's. Spawning gravels ecological values and is an important habitat for native fish, Rennie Property 2464200 5722100 occur downstream until the bed becomes silted and sluggish at Selwyn Huts. According to the NZFFD seven fish invertebrates and brown trout. The Selwyn River is also a major D/S of Intake species are present and include threatened lamprey, longfin eel and inanga. No brown trout were recorded from this tributary of Te Waihora/Ellesmere. The Lower Selwyn River is known reach but are known to be present. No water quality or invertebrate data is available for this reach. to be habitat for a significant population of longfin eels. High ecological values. The lower Selwyn River has permanent flow at Coes Ford, is partially channelised and contained within flood embankments. Trout spawning values are high despite a significant decline since the mid The lower Selwyn River downstream of the intermittent reach has high 1980's. Spawning gravels occur downstream until the bed becomes silted and sluggish at Selwyn Huts. Technical ecological values and is an important habitat for native fish, Selwyn River at panel assessments suggest that indigenous vegetation values are low, general amenity values are moderate, trout, 2462600 5723400 invertebrates and brown trout. The Selwyn River is also a major Coes Ford native vegetation and natural character values are moderate to high and Mahinga Kai and Mauri values are high. tributary of Te Waihora/Ellesmere. The Lower Selwyn River is known Overall aquatic habitat values were moderate to high. Based on NZFFD records seven species of fish are present to be habitat for a significant population of longfin eels. and include threatened longfin eel, inanga and lamprey. Brown trout are also present. Nitrogen levels are high, otherwise water quality is acceptable. Invertebrate communities are indicative of good water quality. Moderate ecological values. This appears to be a natural stream with a number of drains comprising the headwaters. The Halswell River is one of the larger systems draining into Te At present has no trout spawning habitat which represents a decline since the mid 1980's. Technical panel Waihora/Lake Ellesmere. It contains some threatened native fish, but Knights Creek at assessments suggest moderate values for trout, indigenous vegetation, general amenity, Mahinga Kai and Mauri, but 2473800 5733600 in general has a silt laden bed and impaired ecological communities. Jamiesons Property low values for natural character and high values for native fish. Overall aquatic habitat value is moderate. According The Halswell River is known to be habitat for a significant population of to the NZFFD six species of fish are present including threatened longfin eel and koura. Adult brown trout are longfin eels. The Quaiffes Road Drain has a good population of koura present. No water quality data is available, however, a single invertebrate sample indicated poor water quality.
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Site Easting Northing Minimum flow site ecological values Catchment scale values
The Halswell River is one of the larger systems draining into Te Moderate ecological values. This reach is a natural stream although subject to agricultural drainage and some Halswell River at Waihora/Lake Ellesmere. It contains some threatened native fish, but urbanisation upstream. At present has no trout spawning habitat which represents a decline since the mid 1980's. D/S of Knights 2473800 5733600 in general has a silt laden bed and impaired ecological communities. According to the NZFFD six fish species are present including threatened longfin eel and koura. Adult trout are Creek diversion The Halswell River is known to be habitat for a significant population of present. There is no data on invertebrate communities or nutrient concentrations. The bed is silt laden. longfin eels. The Quaiffes Road Drain has a good population of koura. Moderate ecological values. This reach is a natural stream although subject to agricultural drainage and some urbanisation upstream. At present has no trout spawning habitat which represents a decline since the mid 1980's. The Halswell River is one of the larger systems draining into Te Technical panel assessments suggest moderate values for fish, vegetation, Mauri, general amenity, Wahi tapu & Waihora/Lake Ellesmere. It contains some threatened native fish, but Halswell River at wahi taonga, but high Mahinga Kai values. Overall aquatic habitat value is moderate. According to the NZFFD six 2474500 5733400 in general has a silt laden bed and impaired ecological communities. Leadleys Rd species of fish are present including threatened longfin eel and koura. Adult trout are present. Currently the stream The Halswell River is known to be habitat for a significant population of bed is heavily silted. Water quality information at this location suggests that low dissolved oxygen levels may be longfin eels. The Quaiffes Road Drain has a good population of koura deleterious to aquatic life and a single invertebrate sample suggests poor/fair water quality. Nitrogen and phosphorus levels are high. Low to moderate ecological values. This is a natural stream reach. It has no trout spawning values but adult trout The Halswell River is one of the larger systems draining into Te habitat throughout. The bed is heavily laden with silt. Technical panel assessments suggest indigenous vegetation Waihora/Lake Ellesmere. It contains some threatened native fish, but Halswell River at values are low, natural character is moderate, but trout, general amenity, native fish and Mahinga Kai values are 2474100 5728400 in general has a silt laden bed and impaired ecological communities. Branthwaites good to high. Overall aquatic habitat values are good. However, according to the NZFFD only two species of fish are The Halswell River is known to be habitat for a significant population of present including threatened inanga. Two invertebrate community samples suggested that water quality is poor and longfin eels. The Quaiffes Road Drain has a good population of koura. phosphorus levels are moderate Low to moderate ecological values. This is a natural stream reach. It has no trout spawning values but adult trout The Halswell River is one of the larger systems draining into Te habitat throughout. The bed is heavily laden with silt. Technical panel assessments suggest indigenous vegetation Waihora/Lake Ellesmere. It contains some threatened native fish, but Halswell River at values are low, natural character is moderate, but trout, general amenity, native fish and Mahinga Kai values are 2473084 5727178 in general has a silt laden bed and impaired ecological communities. Ryans good to high. Overall aquatic habitat values are good. According to NZFFD records only two fish species are present The Halswell River is known to be habitat for a significant population of although threatened inanga were recorded. There is little water quality data for this site other than temperature, longfin eels. The Quaiffes Road Drain has a good population of koura. which can be elevated high enough to impair trout populations. There is no invertebrate community data for this site. Moderate ecological values. This reach is an apparently natural stream with unknown trout spawning values. The Halswell River is one of the larger systems draining into Te Technical panel assessments indicated low values for natural character and general amenity, moderate Mauri and Waihora/Lake Ellesmere. It contains some threatened native fish, but Halswell river at 2470800 5726200 natural vegetation values, but high Mahinga Kai, trout and native fish values. Overall aquatic habitat value is high to in general has a silt laden bed and impaired ecological communities. Tobecks Bridge moderate. According to the NZFFD three species of fish are present including threatened longfin eel and inanga. The Halswell River is known to be habitat for a significant population of There is no information about invertebrate communities. Elevated phosphorus levels are present. longfin eels. The Quaiffes Road Drain has a good population of koura. Moderate ecological values. This is a natural stream that has been channelised and straightened. No trout spawning The Halswell River is one of the larger systems draining into Te values remain but adult fish are likely to be present. Technical panel assessments suggest moderate trout and native Waihora/Lake Ellesmere. It contains some threatened native fish, but Halswell River at 2473100 5723200 fish values, but low values for indigenous vegetation, natural character and general amenity. Mahinga Kai values are in general has a silt laden bed and impaired ecological communities. Niels Rd high. Overall aquatic habitat value is moderate. Currently the stream bed is heavily silted. There are no NZFFD or The Halswell River is known to be habitat for a significant population of invertebrate sampling records available. Water quality data indicates high nitrogen and phosphorus. longfin eels. The Quaiffes Road Drain has a good population of koura. The Halswell River is one of the larger systems draining into Te Low to moderate ecological values. This reach of the Halswell River is channelised and contained within flood banks. Waihora/Lake Ellesmere. It contains some threatened native fish, but Halswell River at The bed is heavily laden with silt and contains no trout spawning values. According to the NZFFD only two fish 2475400 5719500 in general has a silt laden bed and impaired ecological communities. Hodgens Bridge species are present - common bully and inanga - with the latter being threatened. Phosphorus levels are slightly The Halswell River is known to be habitat for a significant population of elevated. longfin eels. The Quaiffes Road Drain has a good population of koura. Moderate to high ecological values. This a natural stream, although drains and stormwater do enter the upper reaches. It has good trout spawning values which have shown an improvement since the mid 1980's. Technical The L-11 River is one of the larger spring-fed systems draining into Te panel assessments suggest low values for native fish, indigenous vegetation and Mauri, low to moderate values for Waihora/Lake Ellesmere. It contains some threatened native fish, but L-11 River at Moir's 2469100 5727900 trout and natural character, moderate values for general amenity and high values for Mahinga Kai. Overall aquatic in general has a silt laden bed and impaired ecological communities. Property habitat value is low. However, according to the NZFFD six species of fish are present including the threatened longfin The L-11 is known to be habitat for a significant population of longfin eel, torrentfish and koura. Adult brown trout are present. Water quality data is not available but a single invertebrate eels. community sample was indicative of fair water quality. The degree of siltation increases downstream in this reach Moderate ecological values. This a natural stream although the bed is heavily silt laden and there are no trout The L-11 River is one of the larger spring-fed systems draining into Te L-11 River at 2465710 5723465 spawning values. Technical panel assessments indicated low values for indigenous vegetation, moderate values for Waihora/Lake Ellesmere. It contains some threatened native fish, but Pannetts natural character, general amenity and Mauri, while trout, native fish and Mahinga Kai values are high. Overall, in general has a silt laden bed and impaired ecological communities.
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Site Easting Northing Minimum flow site ecological values Catchment scale values
aquatic habitat had a high value. According to the NZFFD eight species of fish are present including the threatened The L-11 is known to be habitat for a significant population of longfin longfin eel, torrentfish and koura. Introduced rudd (an unwanted fish species), goldfish and brown trout are also eels. present. Water quality data indicates low DO levels are present and this may be deleterious to aquatic life. Nitrogen and phosphorus are elevated. There is no invertebrate community data. The L-11 River is one of the larger spring-fed systems draining into Te Low to moderate ecological values. This is a natural stream. It has no trout spawning values and according to the Waihora/Lake Ellesmere. It contains some threatened native fish, but L-11 River at NZFFD only two species of fish are present: goldfish and rudd. Adult trout are likely to be present but not confirmed 2465672 5721811 in general has a silt laden bed and impaired ecological communities. Wolfes Rd and threatened koura are present. No water quality or invertebrate data are available although the stream is known The L-11 is known to be habitat for a significant population of longfin to be silt laden and occasionally stagnant. eels. Low ecological values. This is a channelised drain with significant siltation issues. Trout spawning values are low Baileys Creek at and have shown a significant decline since the 1980's. Technical panel assessments suggested that trout, Low ecological values. This waterway is severely impacted by siltation 2461400 5726000 Lincoln Leeston Rd indigenous vegetation, natural character and general amenity are all low, while Mauri and native fish values are for its entire length. The upper reaches are ephemeral moderate. No water quality data is available but invertebrate communities are indicative of poor water quality. Moderate ecological values. This is a channelised stream/drain with limited and declining trout spawning values. The bed is silt laden at most locations. Technical panel assessments suggest that trout, indigenous vegetation, natural Low to moderate ecological values. The creek suffers from low flows McGraths Creek at character and general amenity are low, native fish values are low to moderate. Mahinga Kai values are moderate 2460400 5725100 and siltation. There has been a significant decline in the health of this Lincoln-Leeston Rd while overall aquatic habitat values are moderate to high. According to the NZFFD four fish species are present stream since the mid 1980's including threatened longfin eel. Adult trout are present. No water quality is available but invertebrate communities are indicative of poor water quality. Low to moderate ecological values. This is a natural waterway that has been channelised. Trout spawning values Low ecological values. Snake Creek has retained some ecological are good, but have shown a significant decline since the 1980's due to silt accumulation. Technical panel Snake Creek at values, despite siltation, due to the presence of some trout spawning. 2460000 5724700 assessments suggest that trout, native vegetation and general amenity values are low. Native fish values are low to Lincoln Leeston Rd However, water quality in Snake Creek is low. There has been a moderate and overall aquatic habitat values are low. There is no available water quality data, but invertebrate significant loss of flow in the headwaters. communities are indicative of poor water quality. Moderate ecological values. This is a channelised waterway with moderate trout spawning values and fish present, despite the occurrence of silt and stock access. There has been a significant decline in trout spawning value since Moderate ecological values. The Silver Stream has retained some the 1980's. Technical panel assessments suggested that native fish and indigenous vegetation values are low, trout ecological values, despite siltation, due to the presence of some trout Silverstream at 2460798 5725564 values are low to moderate, native vegetation, general amenity and Mauri values are moderate, while Mahinga Kai spawning and native fish. Water quality in the Silver Stream is known Lincoln Leeston Rd values are high. Overall aquatic habitat values are low. According to the NZFFD five species of fish are present and to reduce the overall water quality of the Selwyn River below their includes threatened longfin eel and koura. Brown trout are also present. Water quality data is not available, but confluence. There has been a loss of flow in the headwaters. invertebrate communities are indicative of fair water quality. Moderate ecological values. This is a natural stream with some channelised headwaters and good trout spawning values despite stock access and siltation. There has been a decline in trout spawning since the mid 1980's. Moderate ecological values. The Silver Stream has retained some Silverstream at Technical panel assessments suggest that indigenous vegetation values are low, trout values are low to moderate, ecological values, despite siltation, due to the presence of some trout Selwyn River 2462119 5723522 native fish, natural character and general amenity values are moderate, while Mahinga Kai and Mauri values are high spawning and native fish. Water quality in the Silver Stream is known confluence. and overall aquatic habitat value is low. According to the NZFFD three species of fish are present and include the to reduce the overall water quality of the Selwyn River below their threatened longfin eel. Brown trout have not been recorded but are likely to be present. There is no water quality confluence. There has been a loss of flow in the headwaters. data available but invertebrate communities are indicative of fair water quality. Low ecological values. This waterway is a channelised drain, with limited water flow and stock access. At present Miles Drain at has no trout spawning values which is a significant decline from the mid 1980's. Technical panel assessments Low ecological values. This waterway has been severely degraded 2462975 5723540 Pannets Rd suggested that all values were low other than native fish values, which were moderate. There is heavy siltation over the last 20 years. throughout the drain. Unnamed Drain at Unknown ecological values. This is a channelised drain with very little ecological information available. Invertebrate Pendergast 2462100 5719500 Largely unknown communities are indicative of poor water quality. Property Low ecological values. The Irwell River has suffered considerably from low flows and siltation. Flow diversion Irwell River at Low ecological values. The Irwell River has been severally degraded upstream may be responsible for reduced flow downstream. The upper reaches are now ephemeral and trout Leeston 2457339 5719794 over the last twenty years, and in particular has significantly reduced spawning values have declined from historically good t to nothing. There are no NZFFD records or water quality data Christchurch Rd flow. available for this site, but invertebrate sampling indicates very poor water quality.
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Site Easting Northing Minimum flow site ecological values Catchment scale values
Low to moderate ecological values. The Irwell River has suffered considerably from low flows and siltation. Flow diversion upstream may have reduced flows in the lower reaches. The upper reaches are now ephemeral and trout Low ecological values. The Irwell River has been severally degraded Irwell River at The spawning values have declined to nothing. The NZFFD indicates that at Lake Rd five species of fish are present 2459900 5717800 over the last twenty years, and in particular has significantly reduced Lake Rd although no threatened species. Adult trout have been recorded. Water quality data suggests that low DO levels are flow. likely to impair biotic communities. Nitrogen levels are unusually low, likely due to high plant cover and low flows, and phosphorus is slightly elevated. Invertebrate communities are indicative of poor water quality. Moderate ecological values. This waterway is a road aligned drain which suffers from some siltation. There are good Moderate ecological values. This waterway has good trout spawning Hanmer Rd Drain at trout spawning values but these have declined since the mid 1980's. Four fish species have been recorded by KMA 2459415 5717107 and moderate native fish values. Stock access has been reduced but Lower Lake Rd (2006). The drain is cleared by excavation. Water quality data show that nitrogen and phosphorus are high, while the system is subject to local authority drain management policies. invertebrate community data indicates water quality is poor to fair. Moderate ecological values. This a channelised drain system that suffers from some siltation but has good trout Moderate ecological value. Overall boggy creek is a drain which spawning values which have shown a significant improvement since the mid 1980's due to habitat restoration work. suffers from some siltation but has good trout spawning values which Boggy Creek at According to the NZFFD five fish species are present which includes threatened longfin eel and inanga. Adult brown 2458304 5715571 have shown a significant improvement since the mid 1980's due to Lower Lake Rd trout are also present. Water quality data suggests that low dissolved oxygen (DO) levels may impair ecological restoration work. The upper reaches are ephemeral and nutrient levels communities. Nitrogen and phosphorus levels are high and invertebrate communities are indicative of poor water are high. quality. Low to moderate ecological values. Doyleston Drain is a road aligned waterway with moderate trout spawning values. According to the NZFFD three species of common native fish are present. However, acutely threatened Potentially high ecological values. Overall this waterway is impacted Canterbury mudfish have been recently recorded in the drain, with larval fish likely sourced from tributary drains. Doyleston Drain at by silt on the bed and undergoes mechanical clearing by excavation. 2457942 5714972 Brown trout are not recorded in the NZFFD but are known to be present; Doyleston Drain historically supported a D/S Lake Rd However, Canterbury mudfish populations are extremely rare in this highly valued trout fishery. Habitat modification and altered drainage patterns may have impacted aquatic region and should be protected. communities. Nitrogen and phosphorus levels are elevated and there is potential for low DO to impair ecological communities. Low to moderate ecological values. The upper reaches have some natural channel form but are ephemeral. Trout spawning values are currently low. Technical panel assessments indicated that indigenous vegetation, natural Tramway Reserve character, general amenity and Mauri values are low, trout values are low to moderate and native fish values are Low ecological values in all but the lower reaches downstream of Lake 2456791 5713698 Drain at Lake Rd moderate to high. A single NZFFD record indicated the occurrence of common bullies, but threatened longfin eels Rd have also been observed. The drain suffers from siltation, channelisation and intermittent flow. There is no information on water quality or invertebrate communities. Moderate ecological values. Birdlings Brook is a major tributary of Low to moderate ecological values. This is a natural stream that has undergone some channelisation but also Harts Creek. Due to concerns about stock access and siltation several Birdlings Brook at restoration over the last twelve years. Birdlings Brook had historically high trout spawning values, however these reaches were fenced from stock and planted with native vegetation in 2454994 5712014 Leggs Rd have declined since the mid 1980's. Overall, there is a lack of ecological data for this site. A single invertebrate the late 1990's. However, despite bi-annual monitoring of invertebrates community sample indicated poor water quality. at Lochheads Rd there is little other evidence available about the ecological values of the entire system. Moderate ecological values. This is a natural stream that has undergone some channelisation, but also restoration Moderate ecological values. Birdlings Brook is a major tributary of over the last twelve years. Birdlings Brook had historically high trout spawning values, however these have declined Harts Creek. Due to concerns about stock access and siltation several Birdlings Brook at since the mid 1980's. Technical panel assessments suggest that indigenous vegetation, Wahi tapu and wahi taonga reaches were fenced from stock and planted with native vegetation in 2454670 5712840 Lochheads Rd values are low to moderate, trout and Mahinga Kai values are moderate, natural character and general amenity the late 1990's. However, despite bi-annual monitoring of invertebrates values are moderate to high, while native fish and Mauri values are high. Twenty invertebrate community samples at Lochheads Rd there is little other evidence available about the collected between 1999 and 2009 indicated good water quality. ecological values of the entire system. High ecological values. Harts Creek is a natural stream that has undergone restoration over the last twelve years although siltation is still a problem. Trout spawning values are high. Technical panel assessments suggest that indigenous vegetation values are moderate, natural character values are moderate to high, while trout, native fish, Overall, this waterway has good ecological values, being one of the Harts Creek at general amenity, Mahinga Kai and Mauri values are high. According to the NZFFD five fish species are present which 2456783 5712038 healthiest plains spring-fed tributaries of Te Waihora. Siltation remains Lower Lake Rd includes the threatened inanga. Adult brown trout are also present. Water quality data showed that the water was an issue. cool, but nitrogen levels are elevated. A single invertebrate community sample at Lower Lake Rd indicated fair to good water quality and the same result was gained from nine samples collected close to the stream source at Hills Rd.
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Site Easting Northing Minimum flow site ecological values Catchment scale values
Low to moderate ecological values. This is a drain with unknown trout spawning values. Technical panel Overall this drain has moderate ecological values due to occurrence of Parkin Drain at assessments suggested low values for trout, indigenous vegetation, natural character and general amenity. Native 2458352 5705845 inanga which are likely to be spawning in the system. However, there Taumutu Rd fish values are poor to moderate, Mauri is moderate and Mahinga Kai values are high. According to the NZFFD native is little information available. fish diversity is low and limited to threatened inanga. There is no invertebrate or water quality data available. Moderate ecological values. This is a natural waterway with some drains in the headwaters. Trout spawning values are thought to be low. Technical panel assessments suggest that trout values are low, indigenous vegetation and Overall the ecological values of this stream are moderate. Threatened Waikewai Creek at natural character values are moderate, general amenity is moderate to high and native fish, Mahinga Kai and Mauri fish are present but invertebrate communities are indicative of poor 2458306 5705440 Taumutu Beach values are high. According to the NZFFD eight species of fish are present and include threatened longfin eel and water quality. There is no information available for the upper reaches inanga. Brown trout and Chinook salmon are also present. No water quality data is available, but invertebrate of the system. communities suggest water quality is poor. Taumutu Creek at Unknown ecological values. This is a natural stream with very little ecological information available. Invertebrate 2458000 5705100 Largely unknown D/s Gulliver Intake communities are indicative of poor water quality. Moderate ecological values. An apparently natural stream with fenced banks in the upper reaches and riparian There is very little information available overall for this catchment. The Lee River at vegetation in the lower reaches. Includes limited trout spawning in a headwater tributary and adult habitat mouth is open to the sea via a culvert so fish may have access from 2452457 5706792 Temoana throughout. There are no sites in the NZFFD at this location. The Lee River is impacted by siltation for its entire the sea. The Hei Hei tributary should be regarded as having potential length, but gravel substrate occurs in the Hei Hei tributary. There is no information on water quality or invertebrates high ecological values which should be investigated further. Moderate ecological values. Natural stream with fenced banks in the upper reaches and riparian vegetation in the There is very little information available overall for this catchment. The Lee River at lower reaches. Includes limited trout spawning in a headwater tributary and adult habitat throughout. There is one mouth is open to the sea via a culvert so native fish may have access. 2452200 5705500 Brooklands site in the NZFFD at this location and two species were present. The Lee River is impacted by siltation for its entire The Hei Hei tributary should be regarded as having potential high length, but gravel substrate occurs in the Hei Hei tributary. There is no information on water quality or invertebrates ecological values which should be investigated further. Moderate ecological values. Natural stream with siltation throughout exacerbated by stock access. Technical panel assessments suggest moderate values for fish, vegetation, Mahinga Kai and Mauri, but low values for general Tent Burn at There is very little information available overall for this catchment. The 2452540 5703873 amenity, Wahi tapu & wahi taonga. There are no records in the NZFFD but adult trout are likely to be present Beachcroft mouth is open to the sea via a culvert so native fish may have access. throughout. The Tent Burn suffers from siltation throughout and there is no information on water quality although a single invertebrate sample at BeachCroft suggested poor water quality. Moderate ecological values. Natural stream subject to mechanical clearing in the upper reaches. Includes limited Jollies Brook at trout spawning in the headwaters and adult habitat throughout. According to NZFFD three species of fish are present. There is very little information available overall for this catchment. 2450601 5703489 Bullocks Rd Gravel substrate upstream, but significant siltation and stock access downstream. There is no information on nutrient Permanent mouth closure may prevent access for native fish. concentrations. Moderate ecological values. Natural stream subject to mechanical clearing in the upper reaches. Includes limited Jollies Brook at trout spawning in the headwaters and adult habitat throughout. According to NZFFD one species of fish are present. There is very little information available overall for this catchment. 2451435 5703063 Outlet to sea There is gravel substrate in the upper reaches, but significant siltation and stock access downstream. No information Permanent mouth closure may prevent access for fish from the sea. on nutrient concentrations SDC water race Unknown ecological values. This an artificial water race with flow derived from the Rakaia River. Therefore, water The ecology of this water race is largely unknown, but in general stock (Rakaia) at below 2413990 5732920 quality is likely to be good, although siltation may be a problem. The only existing information is the presence of water races in Canterbury may have moderate ecological values Early's upland bullies recorded in the NZFFD. providing habitat to some generalist fish and invertebrate taxa.
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3.0 ECOLOGICAL MINIMUM FLOW RECOMMENDATIONS 3.1 Introduction Golder (2011) made the following ecological minimum flow recommendations for rivers in the Te Waihora/Lake Ellesmere catchment. Flow recommendations were indexed to 7DMALF, with minimum flows of at least 90 % of 7DMALF recommended for flow-sensitive sites, and flows of 70 to 90 % of 7DMALF for less sensitive sites. The following summarises the Golder (2011) recommendations: Minimum flows of at least 90 % of 7DMALF for: . Spring-fed rivers with 7DMALF ≤300 L/s . Hill-fed rivers – The upper Selwyn River and Banks Peninsula rivers . Canterbury mudfish sites – Hororata area and Waianiwaniwa Valley
Minimum flows of 70 to 90 % of 7DMALF for: . Spring-fed rivers with 7DMALF >300 L/s
The following section applies the Golder (2011) recommendations to each of the minimum flow sites, using the 7DMALF statistics recently calculated by CRC. Seventy percent of 7DMALF was used to calculate recommended minimum flows for larger spring-fed rivers, and 90 % of 7DMALF for the other, more flow- sensitive, river types. This was done for simplicity, in preference to showing a range of recommended minimum flows. Note that 7DMALF was calculated from “naturalised” flow data, whereby known takes were added back into the flow record by CRC prior to calculating 7DMALF. Naturalised flows are used in preference to recorded flows in this report, so that the 7DMALF low flow statistic provides a baseline unaffected by abstraction, to compare with current minimum flows, and to calculate recommended minimum flows for protection of ecological values. If recorded 7DMALF was used as a baseline for setting minimum flows, then there could be a progressive reduction in minimum flows during each flow review, resulting in reduced low flows and progressive decline in aquatic ecosystem health.
3.2 Recommended Minimum Flows Figure 2 and Table 2 compare current and recommended minimum flows for existing minimum flow sites in the catchment. It is clear from Figure 2 that current minimum flows are lower than recommended for protection of ecological values at many sites in the catchment. Figure 2 also shows that this trend is most evident for larger rivers (7DMALF >200 L/s), with 14 of the 17 larger rivers having lower than recommended minimum flows. In contrast, only two of the eight smaller rivers (7DMALF ≤200 L/s) had lower than recommended minimum flows. The pattern of current minimum flows being lower than recommended for larger rivers, but not smaller rivers, is the reverse of the pattern reported by Golder (2011) for rivers in the same catchment. Thus, Golder (2011) found that existing minimum flows represented 66 % of 7DMALF for smaller rivers and 78 % of 7DMALF for larger rivers. Closer inspection of the data indicates that 7DMALF estimates have changed considerably at a number of sites since the Technical Panel work was undertaken a decade ago. Large differences between Technical Panel and recent 7DMALF estimates are evident for the Halswell River at Niels (increase from 636 to 956 L/s), the Halswell River at Ryans (increase from 515 to 760 L/s), and Birdlings Brook at Leggs (increase from 345 to 637 L/s). According to CRC hydrologists, a likely reason for this discrepancy in 7DMALF estimates is that current flow statistics are based on a more extensive flow
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gauging database than was available for the Technical Panel work, plus the earlier 7DMALF estimates were likely based on recorded data, rather than the naturalised data used here. Other notable patterns include the following: Current minimum flows are less than 50 % of 7DMALF for 12 of the 25 sites with current minimum flows and 7DMALF estimates. The Hororata River minimum flow of 30 L/s is particularly low relative to 7DMALF of 424 L/s. This is apparently because of complex hydrology in the vicinity of the recorder site, with natural flow losses and an existing large stockwater take in the immediate vicinity, plus flow gains from springs further downstream. Doyleston Drain has a minimum flow of 60 L/s, which is very high compared to the 7DMALF of 6 L/s. This means that abstraction currently ceases at flows well above natural low flows. Halswell River minimum flow sites: Current minimum flows are very low (24-55 % of 7DMALF).
1400
1200
1000
800
600
400 Current minimum flow(L/s)
200
0 0 200 400 600 800 1000 1200 1400 Recommended minimum flow (L/s)
Figure 2: Relationship between current and recommended minimum flows. Data points below the green diagonal line have current minimum flows that are lower than recommended for protection of ecological values.
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Table 2: Current and recommended minimum flows for existing minimum flow sites. Current Recommended 7DMALF Site minimum Flow minimum flow (L/s) (L/s) (L/s)
Kaituna River at Kaituna Valley Rd* 35 60 32 Hawkins River at Willows-Dalethorpe Rd* 37 35 33 Selwyn River at Whitecliffs* 792 550 713 Selwyn River at Coes Ford* 750 600 675 Hororata River at Haldon Water Race Bridge* 424 30 382 Knights Creek at Jamiesons Property* 253 64 228 Halswell River at Leadleys Rd 582 230 407 Halswell River at Ryans Bridge 760 – 532 Halswell River at Tobecks Bridge 934 280 654 Halswell River at Niells Rd 926 510 648 Halswell River at Hodgens Bridge 1157 280 810 L-II River at Pannetts Rd 1820 – 1274 L-II River at Wolfes Rd 1771 560 1240
Baileys Creek at Lincoln Leeston Rd* 13 40 12 Silverstream at Lincoln Leeston Rd* 88 60 79 Snake Creek at Lincoln Leeston Rd* 70 30 63 Miles Drain at Pannets Rd* 14 30 13 Irwell River at Lake Rd 910 300 637 Hanmer Rd Drain at Lower Lake Rd 369 100 258 Boggy Creek at Lower Lake Rd* 290 100 261 Doyleston Drain at D/S The Lake Rd* 6 60 5 Birdlings Brook at Lochheads Rd 685 200 480 Birdlings Brook at Leggs Rd 637 150 446 Harts Creek at Lower Lake Rd 1068 1000 748 Harts Creek at Timber Yard Rd 1370 – 959 Waikekewai Creek at Taumutu Beach* 38 100 34 Lee River at Temoana 935 700 655 Jollies Brook at outlet to sea 424 360 297
Notes: “–“ indicates sites with flow recorders that currently have no minimum flow. “*” indicates flow-sensitive sites, as defined in Section 3.1.
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3.3 Ecological State and Minimum Flows Ecological flow recommendations typically take into account the significance of the ecological values present and the flows required to sustain those values (Beca 2008). It may therefore be tempting to provide lower levels of protection (i.e., lower minimum flows) for streams that have relatively low ecological value. For example, the Irwell River and Doyleston Drain are both considered to currently have relatively low ecological value, and it could be argued that they should therefore have a lower proportion of 7DMALF as the minimum flow. For such rivers, a multitude of factors likely influence their current ecological state, including flow, water quality and quality of instream and riparian habitat (Golder 2011). Therefore, one of the problems with assigning a low level of protection based on current ecological condition is that if other factors such as water quality and habitat quality are improved, but flows remain low, then it is possible that improved ecological health will become limited by low flow. Another locally-relevant example can be drawn from the lowland tributaries of the Selwyn River, including Snake Creek and Baileys Creek. These streams have provided significant spawning habitat for brown trout in the 1980s, but more recent observations in 2005 indicated that the streams suffer from low flows and heavy bed siltation (Taylor & Good 2006). Riparian protection and enhancement in these small streams could substantially improve instream habitat quality, as has been observed in nearby Harts Creek and Boggy Creek. However, low flows could prevent the restoration goals being realised, if there is insufficient depth and stream flow to support key ecological values such as trout spawning and adult eel habitat. The Canterbury Water Management Strategy (CWMS) has goals for setting environmental flows and improving water quality and biodiversity values in lowland streams. For example, one strategic goal is to have nutrient limits and good or improved ecological health in all lowland streams in the region by 2040. It is considered inappropriate here to recommend low minimum flows for degraded waterways in the Te Waihora catchment, given that improved ecological health is a strong directive of the CWMS, and because low minimum flows could thwart attempts to improve ecological health via other activities such as reduced nutrient concentrations, and improved riparian condition and instream habitat quality. In summary, lower minimum flows are not recommended for degraded rivers in the Te Waihora catchment, as it could thwart attempts to improve overall ecosystem health by means such as improving riparian condition and keeping stock from rivers. Providing minimum flows of at least 70 to 90 % of naturalised 7DMALF, depending on the river type and sensitivity to flow change (Section 3.1) is considered to provide an appropriately high level of protection for the aquatic values present in the catchment. It is also consistent with recommendations based on the Technical Panel, habitat modelling, and the draft NES.
3.4 Priority Sites Ecological minimum flows recommended by Golder (2011) were proposed as a method for protecting water quality and habitat for aquatic species. Therefore, sites with lower than recommended minimum flows are more likely to be impacted by low flows than other sites. In addition, minimum flows will not protect rivers from the effects of cumulative groundwater abstraction or stream-depleting groundwater takes that are not tied to minimum flow restrictions. The sites at greatest ecological threat from low river flows are those with the biggest gap between current and recommended minimum flows, and where groundwater abstraction is not being limited by minimum flow restrictions or a suitable allocation limit. Degraded physical habitat and water quality will also impact on these sites, but flow is an essential requirement for aquatic species. With regards to protection of ecological values, it would be preferable for all sites to have minimum flows at or above levels recommended in this report. However, it is acknowledged that CRC needs to balance potentially competing demands for water, and that there is therefore a need to prioritise issues. Therefore, for the purposes of setting management priorities, we have classified minimum flow sites as follows: High priority: Current minimum flows are less than 50 % of 7DMALF Moderate priority: Current minimum flows are below recommended, but above 50 % of 7DMALF
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Low priority: Current minimum flows are at or above recommended levels Figure 3 summarises these recommendations and shows that many minimum flows sites are a high priority for increasing minimum flows, because they currently fall below 50 % of 7DMALF. Although many of those high priority sites are not considered particularly flow-sensitive (i.e., the minimum flow recommendation is 70 to 90 % of 7DMALF), minimum flows below half of 7DMALF are considered too low to protect ecological values at even these less-sensitive sites. The use of 50 % as the high priority cut-off is based on expert judgement, but is also supported by research and expert opinion that has found a high risk of deleterious ecological effects if more than 40 % of 7DMALF is abstracted, regardless of the river type (Beca 2008). If minimum flows are not increased at these high risk sites, ecological values could still be improved via habitat and water quality improvements, but there is considerable risk that habitat and water quality enhancements will be unsuccessful if minimum flows remain low.
140
120
100
80
60 % 7DMALF 40
20 … … … 0 … - II River at Wolfes Rd Wolfes at River II - L Irwell River at Rd Lake River Irwell Lee River at Temoana at River Lee II River at Pannetts Rd Pannetts at River II - L Hawkins River at at Willows River Hawkins Miles Drain at Pannets Rd at Drain Pannets Miles Halswell River at Rd at Niells River Halswell Selwyn River at at Whitecliffs River Selwyn Selwyn River at at Ford Coes River Selwyn Birdlings Brook at Leggs Rd Leggs at Brook Birdlings Knights Creek at at Jamiesons Creek Knights Jollies Brook at outlet to to at outlet sea Brook Jollies Halswell River at Rd at Leadleys River Halswell Harts Creek at at Creek Rd Lake Lower Harts Waikekewai Creek at Taumutu Taumutu at Creek Waikekewai Halswell River at Ryans Bridge at Ryans River Halswell Harts Creek at at Rd Creek Yard Timber Harts Boggy Creek at Rd at Lake Lower Creek Boggy Hororata River at at Haldon Water River Hororata Birdlings Brook at Lochheads Rd Lochheads at Brook Birdlings Halswell River at Tobecks Bridge at Tobecks River Halswell Halswell River at at Bridge Hodgens River Halswell Kaituna River at Rd at Valley Kaituna River Kaituna Silverstream at Lincoln Leeston Rd Leeston Lincoln at Silverstream Snake Creek at Lincoln Leeston Rd at Leeston Lincoln Creek Snake Hanmer Rd Drain at Rd at Lake Drain Lower Hanmer Rd Baileys Creek at Lincoln Leeston Rd at Leeston Lincoln Creek Baileys Doyleston Drain at D/S D/S The Lake at Drain Rd Doyleston
Figure 3: Current minimum flows expressed as a percentage of 7DMALF. Minimum flows below the dashed orange line are a moderate priority for increasing minimum flows, while bars falling below the solid red line indicate high priority sites. The left orange dashed line indicates flow-sensitive sites, while the lower dashed line indicates less flow-sensitive sites.
4.0 ADEQUACY OF EXISTING MINIMUM FLOW SITES 4.1 Background Many of the minimum flow sites in the Te Waihora/Lake Ellesmere catchment lack flow recorders and are infrequently gauged. This means that it is difficult for existing water users to know when they should cease taking water due to minimum flow conditions being triggered. Furthermore, there has been little scrutiny as to whether the location of existing minimum flow sites adequately protect the aquatic values present in the catchment, and CRC is interested to know whether the total number of minimum flow sites could be reduced.
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Golder ecology staff met with CRC hydrology staff to discuss the results of recent hydrological investigations and to assess the adequacy of number and location of existing minimum flow sites. This initially involved hydrology staff scrutinising correlations between primary recorder sites and minimum flow sites without flow recorders to see whether flows at non-recorder sites could be represented or monitored by recorder sites. Then Golder ecologists looked at the distribution of minimum flow sites to evaluate whether they adequately covered the streams and associated ecological values present in the catchment.
4.2 Geographic Coverage Permanent flow recorders are present on three rivers in the upper catchment, six rivers in the lower catchment, and there is a flow recorder on one Banks Peninsula River (Table 3). Although there are numerous minimum flow sites with no permanent flow recorders, most of these sites have flows correlated to varying degrees with permanent recorder sites, as summarised in Table 3 below. Clark (2011) recommended that the degree of correlation between some sites was sufficient that minimum flows could be effectively managed from a recorder site on another river. For other rivers with a poorer correlation with a recorder site (typically an r² of <0.8), Clark (2011) recommended that the flow recorder could be used to indicate when flows are likely to approach the minimum flow, which would be verified by a physical gauging at the minimum flow site. The only sites that were not correlated with recorder site were the L-II River at Moirs and the Lee River at Te Moana. Clark (2011) indicated that multiple inflowing spring sources between the flow recorder at Pannets Road and the minimum flow site was a possible reason for the poor correlation between the L-II Moirs Road site and the flow recorder. The Lee River at Te Moana has few gaugings over a narrow range of flows, which is the likely reason for its poor correlation with the flow recorder at Brooklands (Clark 2011). Further gaugings over a wider range of flows may improve the correlation between the Te Moana and Brooklands sites on the Lee River.
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Table 3: Sites with permanent flow recorders and sites with flows correlated to recorder site flows. Adapted from Clark (2011). Recorder site Minimum flow sites correlated with recorder site R² Upper catchment Selwyn River at Whitecliffs Hawkins River at Willows Hororata River at Mitchells Rd Hororata at Downstream of Haldon Intake 0.90 Lower Catchment Knights Creek at Jamiesons 0.85 Halswell River at Tobecks Rd 0.88 Halswell River at Ryans Bridge Halswell River at Leadleys Rd* 0.81 Halswell River at Niells Rd* 0.70 L-II River at Pannets Rd L-II River at Wolfes Road 0.87 Irwell River at The Lake Rd* 0.81 Halswell River at Hodgens* 0.85 Selwyn River at Coes Ford Miles Drain at Pannets Rd* 0.77 Snake Stream at Lincoln-Leeston Rd* 0.89 Silverstream at Lincoln-Leeston Rd* 0.92 Boggy Creek at The Lake Rd 0.92 Hanmer Rd Drain at The Lake Rd 0.88 Doyleston Drain at The Lake Rd Baileys Creek at Lincoln-Leeston Rd* 0.77 Taumutu Creek at Taumutu Beach* 0.63 Birdlings Brook at Lochheads Rd 0.89 Harts Creek at Timber Yard Rd Birdlings Brook at Leggs Rd 0.92 Harts Creek at Leeston-Lake Rd 0.98 Jollies Brook at piped outfall* 0.63 Lee River at Brooklands Lee River at Te Moana (subject to further gaugings to Not confirm)* available Banks Peninsula Kaituna River Notes: * Indicates a relatively poor correlation with recorder site flows at the time of writing, particularly at low flows. The R² value indicates how close the relationship is. A R² value close to 1 indicates a close correlation, with little scatter, a value close to 0 indicates a weak correlation, with a great deal of scatter.
Overall, the existing flow recorders in the Te Waihora catchment provide good geographic coverage of the range of river types and ecological values present. Key ecological values in the upper catchment include Canterbury mudfish in the Hororata River area and brown trout in the Selwyn River, and both rivers have permanent flow recorders. The lower Selwyn River is particularly valued as a trout fishery and has a permanent flow recorder, whilst most lowland rivers are valued eel fisheries and many also provide trout habitat, including adult, juvenile and spawning habitat. Based on the flow correlations undertaken by CRC, flows at most minimum flow sites in the lower catchment can be predicted using existing flow recorder sites. It is therefore concluded that the range of ecological values present in the Te Waihora catchment is adequately covered by existing flow recorder sites, either directly or indirectly via correlation with a recorder site.
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4.3 Reduction of Minimum Flow Sites Many minimum flow sites in the Te Waihora catchment do not have flow recorders and were historically seldom gauged, so CRC is interested in reducing the number of minimum flow sites. Based on the flow correlations summarised in Table 3, it is clear that flows at a number of sites without recorders can be represented by “core” minimum flow sites with flow recorders. However, while the use of “core” minimum flow sites would help monitor the cumulative effects of groundwater abstraction, it would not monitor localised effects of groundwater or surface water abstraction. Golder (2011) suggested a dual minimum flow regime for the Te Waihora catchment, with core minimum flow indicator sites that have permanent flow recorders and that all sites with similar hydrological conditions are tied to, plus minimum flows for each river that does not have a permanent flow recorder. Under such a system, sites without flow recorders would have two minimum flows: one that is tied to a core site and one that is based on flows in the individual river. Clark (2011) suggested an alternative tiered approach, with minimum flow sites being moved to a recorder site if flows were closely correlated between the two sites. For sites with a weaker correlation to a recorder, Clark (2011) suggested that when flows at the recorder site get close to minimum flow conditions, this acts as a trigger for CRC staff to gauge the site without a flow recorder to check if it is at or approaching minimum flow conditions. We recommend against significantly reducing the number of minimum flow sites in the catchment, and suggest that the regression equations provided by Clark (2011) can be used by consent holders to monitor flows at recorder sites and infer what the flow is likely to be at the minimum flow site closest to their water take. As flows approach minimum flow conditions based on correlation with the recorder site flows, this would trigger either CRC or the consent holder to gauge river flow at their minimum flow site, to ensure that the minimum flow condition is being complied with. Using the example shown in Figure 4, this approach would protect against abstraction reducing flows to unacceptably low levels in smaller tributaries (Site “A” in Figure 4) or separate waterways (Site “B”) from the flow recorder site. In contrast, if all sites with a correlation to a flow recorder were solely managed by flows measured at the recorder site, it is conceivable that localised effects of abstraction would be undetected, which could have consequences for river drying, water quality, and habitat.
Minimum flow site “A”
Minimum flow site “B”
Flow recorder
Lake
Figure 4: Schematic showing minimum flow sites on smaller tributaries (Site "A") and different rivers altogether (Site "B") from the river where the flow recorder is located. Abstraction could result in adverse effects on river flow at these minimum flow sites if their flows are only monitored at the flow recorder site.
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The proposed approach to managing minimum flows means there would be no reduction in the number of minimum flow sites, and would in fact allow for additional minimum flow sites to be created if new takes occur on tributaries that currently lack a minimum flow site nearby. To protect ecological values, we recommend that minimum flows indexed to naturalised 7DMALF (see Section 3.1 above) are applied to any new surface or hydraulically connected groundwater takes from rivers that currently lack minimum flows. The consent applicant would need to undertake sufficient flow gaugings on the tributary to establish a relationship with a recorder site, so that 7DMALF can be estimated at the new site, and so that flows can be monitored by an existing flow recorder site.
5.0 SUMMARY This report has summarised ecological values present at existing minimum flows sites, recommended minimum flows for each minimum flow site, and has discussed the adequacy of existing minimum flow sites to protect aquatic ecology. The following bullet points summarise key points in this report: Despite widespread habitat degradation and frequently elevated nutrient concentrations, most minimum flow sites support a range of native fish species and brown trout, and may be considered to have at least moderate ecological value. Sites with high ecological value include Prices Stream and Kaituna River, which drain Banks Peninsula and are characterised by stony beds, healthy invertebrate fauna, and the presence of threatened native fish such as longfin eel, inanga and lamprey. The hill-fed Selwyn River and its tributaries, the Hawkins and Horarata Rivers are also considered to have high ecological value, again due to the predominantly silt-free stony bed sediments, healthy invertebrate populations, and the presence of acutely threatened Canterbury mudfish populations in the upper catchment. Harts Creek is one of the few spring-fed lowland streams that is considered to have high ecological values, as it supports brown trout spawning and adult trout habitat, plus has a diverse native fish fauna, and has received substantial riparian enhancement and protection. Minimum flow sites with relatively low ecological value include Baileys Stream, Snake Creek, Miles Drain, the Irwell River, and Doyleston Drain. All of these waterways have significant sedimentation and many have low flows. Current minimum flows are lower than recommended for protection of ecological values at many sites in the catchment. For example, minimum flows are less than 50 % of 7DMALF for 12 of the 25 sites with current minimum flows and 7DMALF estimates. Sites with minimum flows less than 50 % of 7DMALF are considered priorities for increasing minimum flows. It is considered inappropriate to recommend low minimum flows for degraded waterways in the catchment, given that improved ecological health is a strong directive of the CWMS, and because low minimum flows could thwart attempts to improve ecological health via other activities such as reduced nutrient concentrations, and improved riparian condition and instream habitat quality. The range of ecological values present in the Te Waihora catchment is considered adequately covered by existing flow recorder sites, either directly (i.e., the minimum flow site has a flow recorder) or indirectly, via correlation with a recorder site. We recommend against reducing the number of minimum flow sites in the catchment, now that it has been shown that most minimum flow sites have some degree of correlation with a recorder site. The regression equations provided by Clark (2011) can be used by consent holders to monitor flows at recorder sites and infer what the flow is likely to be at the minimum flow site closest to their water take.
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6.0 REFERENCES Booker DJ, Graynoth E 2008. Instream habitat and flow regime requirements for Birdlings Brook, the Halswell River, Harts Creek, and the Lee River. Report prepared by NIWA for Environment Canterbury, Environment Canterbury Report No. U08/51. Booker DJ, Graynoth E 2008: Instream habitat & flow regime requirements in the Lower Selwyn River. Report prepared by NIWA for Environment Canterbury, Environment Canterbury Report No. U08/8, February 2008. Burrell GP 2007. Evidence of Gregory Peter Burrell in relation to resource consent applications to the Canterbury Regional Council for water permits to abstract groundwater from the Selwyn-Waimakariri Groundwater Zone, July 2007. Clark D 2011. Rationalisation of minimum flow sites in the Lake Ellesmere/Te Waihora catchment. Environment Canterbury memorandum from Dan Clark to Alastair Picken, August 2011. Golder 2011. Te Waihora/Lake Ellesmere catchment: ecological values and flow requirements. Prepared for Canterbury Regional Council. Golder Report No. 0978110119, May 2011. Golder 2012. Te Waihora/Lake Ellesmere catchment: ecological impacts of increasing flow allocation. Prepared for Canterbury Regional Council. Golder Report No. 0978110119, March 2012. Jellyman D, Graynoth E 2010. The importance of tributary streams of Te Waihora/Lake Ellesmere in maintaining populations of longfin eels. Prepared for Environment Canterbury, NIWA Report No. CHC2010- 0, June 2010.
Kingett Mitchell Limited 2006. Central plains water enhancement scheme: effects of construction, damming, diversion and water use on benthic ecology. Report prepared for URS, Report No. URSNZ-CHC-004, September 2006. Kingett Mitchell Limited 2006. Central plains water enhancement scheme: effects of construction, damming, diversion and water use on fish and recreation. Report prepared for URS, Report No. URSNZ-CHC-004, September 2006. Kingett Mitchell Limited 2006. Leeston North subdivision AEE. Prepared for Connell Wagner, Report No. CONWA-CAN-002, September 2006.
Langlands P, Elley R. 2000. Survey of salmonid distribution and habitats in the Canterbury Region. Environment Canterbury Report U00/31. Larned ST 2006. Statement of evidence of Scott Thomas Larned in relation to applications for water permits to take and use groundwater in the Rakaia Selwyn groundwater allocation zone. Maw RK 2007. Planning report on the review of the environmental minimum flow and water allocation for Knights Creek, the Halswell River, the LII River, the Kaituna River and Prices Stream. Environment Canterbury Report U07/61. Taylor M, Good M 2006. Brown trout spawning in the Lake Ellesmere (Te Waihora) tributaries, and some surrounding catchments. Prepared for Canterbury Regional Council. Report No. U06/79. 129p.
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APPENDIX A Report Limitations
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REPORT LIMITATIONS
This Document has been provided by Golder Associates (NZ) Ltd (“Golder”) subject to the following limitations:
(i). This Document has been prepared for the particular purpose outlined in Golder’s proposal and no responsibility is accepted for the use of this Document, in whole or in part, in other contexts or for any other purpose.
(ii). The scope and the period of Golder’s Services are as described in Golder’s proposal, and are subject to restrictions and limitations. Golder did not perform a complete assessment of all possible conditions or circumstances that may exist at the site referenced in the Document. If a service is not expressly indicated, do not assume it has been provided. If a matter is not addressed, do not assume that any determination has been made by Golder in regards to it.
(iii). Conditions may exist which were undetectable given the limited nature of the enquiry Golder was retained to undertake with respect to the site. Variations in conditions may occur between investigatory locations, and there may be special conditions pertaining to the site which have not been revealed by the investigation and which have not therefore been taken into account in the Document. Accordingly, additional studies and actions may be required.
(iv). In addition, it is recognised that the passage of time affects the information and assessment provided in this Document. Golder’s opinions are based upon information that existed at the time of the production of the Document. It is understood that the Services provided allowed Golder to form no more than an opinion of the actual conditions of the site at the time the site was visited and cannot be used to assess the effect of any subsequent changes in the quality of the site, or its surroundings, or any laws or regulations.
(v). Any assessments made in this Document are based on the conditions indicated from published sources and the investigation described. No warranty is included, either express or implied, that the actual conditions will conform exactly to the assessments contained in this Document.
(vi). Where data supplied by the client or other external sources, including previous site investigation data, have been used, it has been assumed that the information is correct unless otherwise stated. No responsibility is accepted by Golder for incomplete or inaccurate data supplied by others.
(vii). The Client acknowledges that Golder may have retained subconsultants affiliated with Golder to provide Services for the benefit of Golder. Golder will be fully responsible to the Client for the Services and work done by all of its subconsultants and subcontractors. The Client agrees that it will only assert claims against and seek to recover losses, damages or other liabilities from Golder and not Golder’s affiliated companies. To the maximum extent allowed by law, the Client acknowledges and agrees it will not have any legal recourse, and waives any expense, loss, claim, demand, or cause of action, against Golder’s affiliated companies, and their employees, officers and directors.
(viii). This Document is provided for sole use by the Client and is confidential to it and its professional advisers. No responsibility whatsoever for the contents of this Document will be accepted to any person other than the Client. Any use which a third party makes of this Document, or any reliance on or decisions to be made based on it, is the responsibility of such third parties. Golder accepts no responsibility for damages, if any, suffered by any third party as a result of decisions made or actions based on this Document.
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APPENDIX B Technical Panel Value Scores
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Native Indigenous Natural General Mahinga Wāhi tapu & wāhi Aquatic Minimum Flow Site Trout Mauri fish vegetation character amenity kai taonga habitats Knights Stream 3 5 3 1 3 3 3 Present 3 Halswell R @ Leadleys 3 3 3 3 3 5 3 Present upstream 3 Halswell R @ Branthwaites 1 3 1 1 2 5 3 Present upstream 3 Halswell R @ Ryans 4 5 1 3 4 5 Present locally 4
Halswell @ Tobecks 4 5 2 1 1 5 3 - 4 Halswell R @ Neills 3 3 1 1 1 5 - 3
LII River @ Moirs 2 1 1 2 3 5 1 - 1 LII River @ Pannetts 5 5 1 3 3 5 3 Absent 5 Bailey's Ck @ Lincoln-Leeston Rd 1 3 1 1 1 3 1
McGraths Ck @ Lincoln-Leeston Rd 1 2 1 1 1 3 4 Not ranked 4 Snakes Ck @ Lincoln-Leeston Rd 1 2 1 1 Present 1
Silverstream Ck @ Lincoln-Leeston Rd 2 1 1 3 3 5 3 Present 1 Silverstream @ Selwyn R Confl. 2 3 1 3 3 5 5 Present 1 Selwyn R@Coes Ford 4 4 1 4 3 5 5 Present 4 Miles Dr @ Pannetts Rd 1 3 1 1 1 1 1 Not ranked 1 Kaituna River 1 3 2 4 1 5 5 Not present 2 Prices Stream 1 3 2 3 3 5 1 Present 1 Birdlings Brook @ Locheads Rd 3 5 2 4 4 3 5 1
Harts Creek @ Timberyard Road 5 5 3 4 5 5 5 Present
Parkin Drain @ Taumutu Rd 1 2 1 1 1 5 3 Present downstream
Waikekewai Creek @ Marae 1 5 3 3 4 5 5 Present upstream
Taumutu Creek @ Beach 5 5 3 3 3 5 5 Present upstream
Lee River @ Brooklands 5 5 4 5 4 5 5 Present upstream
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Native Indigenous Natural General Mahinga Wāhi tapu & wāhi Aquatic Minimum Flow Site Trout Mauri fish vegetation character amenity kai taonga habitats Tentburn @ Beachcroft 3 3 3 3 2 3 3 1
Jollies Brook @ Bullocks Rd 3 5 2 2 3 5 3 Present downstream
The above table summary is adapted from a series of unpublished draft CRC reports produced as part of an initial review of minimum flows for rivers in the catchment. The review used an Technical Panel assembled specifically for the catchment flow review process, with expertise in the areas of trout, native fish, general aquatic habitat, general amenity, indigenous vegetation, and Maori values. The Technical Panel visited streams during low flow conditions in summer 2003 and 2005, and ranked each waterway according to the values it supported. Each panellist then used their professional judgement to recommend the minimum flow required to sustain a given instream value. We converted panellist “value” scores to numbers from 1 to 5, with a “low” score receiving a 1, “moderate” receiving a 3, and “high” value receiving a score of 5. Blank cells indicate where data was not collected for that site and value combination.
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