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 June 2012 Report No. 0978110119-002-R-Rev0 i TE WAIHORA CATCHMENT ECOLOGICAL FLOWS APPENDICES APPENDIX A Report Limitations APPENDIX B Technical Panel Value Scores June 2012 Report No. 0978110119-002-R-Rev0 ii 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 2400000 2420000 2440000 2460000 2480000 . S d t H L ) 7 0 0 Z 1 0 0 N 0 0 ( S 0 0 s H 6 6 e t 7 7 ¯ 7 a 5 Legend 3 5 i c o s *# 25 s A *# Minimum flow and additional data sites r e d l 1. Jollies Brook at Outlet to sea o G 2. Lee at Temoana © 3. Halswell River at D/S of Knights Creek diversion . t h g 4. Halswell River at Leadleys Rd i r y p 5. Halswell River at Niels Rd o c s 6. Halswell River at Tobecks Bridge e 4 g *# 29 n 7 i 7. Knights Creek at Jamiesons Property r f H n i 8. Kaituna River at Kaituna Valley Rd S n o i s 9. L-II River at Moir's Property s i m r 10. L-II River at Wolfes Rd e p n 11. Birdlings Brook at Leggs Rd e t t SH73 i r 12. Birdlings Brook at Lochheads Rd 0 0 w 0 0 t 0 0 u 0 13. Boggy Creek at Lower Lake Rd 0 o 4 4 h t 7 7 i 5 14. Doyleston Drain at D/S The Lake Rd 5 w t r a 15. Halswell River at Hodgens Bridge p n i 16. Hanmer Rd Drain at Lower Lake Rd r *# 26 o y l l 17. Harts Creek at Lower Lake Rd o h 7 w 18. Irwell River at Leeston Christchurch Rd r 3*#*# e *# 4 h 19. Irwell River at The Lake Rd 32 t i 1 e SH n 20. Waikekewai Creek at Taumutu Beach a l p 21. Selwyn River at Rennie Property D/S of Intake s i h t f 22. Taumutu Creek at D/s Gulliver Intake 33 o *# # n 23.