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Water Quality – Lake Waikare

Water Quality – Lake Waikare. Presentation to Waikato District Council 24 June 2014. Presentation outline. Context - Lake Waikare and surrounding catchment Lake Waikare water quality challenge Existing governance arrangements Future. Lake Waikare Context.

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Water Quality – Lake Waikare

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  1. Water Quality – Lake Waikare Presentation to Waikato District Council 24 June 2014

  2. Presentation outline • Context - Lake Waikare and surrounding catchment • Lake Waikare water quality challenge • Existing governance arrangements • Future

  3. Lake Waikare Context • One of many shallow lowland peat lakes in the Waikato delta • Lower Waikato Flood Protection scheme • Area of significance for Waikato-Tainui • Whangamarino wetland • Catchment land use and sedimentation • Shallow lakes accord (Waikato-Tainui, WDC, DoC, WRC)

  4. 35 Lower Waikato Lakes 28 21 • 25 lakes in the Lower Waikato zone • 3 provisionally ranked in Top 10 Waipa/Waikato/ Hamilton lakes • Lakes Rotokawau(3), Areare (9) and Waahi(10) 16 3 38 11 42 40 10 9 13

  5. Lake Waikare Context • A shallow lake, high sediment input • Flood control scheme lake level storage and management • Large sediment inflow from Matahuru catchment • Downstream impacts of sediment through the wetland • Current Waikare gate consent compliance review • Other consents to discharge to Lake Waikare

  6. Rangiriri Spillway & 1971 when in operation

  7. Lower Waikato Flood Protection Scheme

  8. Lower Waikato Zone

  9. Lake Waikare water quality • Nitrogen, phosphorus – promote algal growth • Sediment (reduced clarity impacts ecology and suitability for contact recreation) • Wind and pest fish disturb bottom sediments

  10. Monoraphidium sp. Red pigment “zeaxanthin”

  11. Water quality in some shallow lakes 2008-12

  12. Estimated phosphorus loads from lakes’ catchments

  13. Lake Waikare, P concentrations 1996-2014

  14. Matahuru Catchment • Soil stability • 65% of catchment unstable • evidence of past erosionon hill slopes • Erosion mainly landslides, gully erosion and stream bank erosion • Soil Conservation • Present on 4337 ha (42%) of catchment • Absent and required on 1340 ha (13%) • Upgrades to conservation required on 1445 ha (14%)

  15. Matahuru Catchment

  16. Matahuru Catchment

  17. Existing Governance Arrangements

  18. Land administered by DOC, WRC & Waikato –Tainui in the vicinity of Lake Waikare & Whangamarino Wetland

  19. Land Ownership • Lake bed owners – Waikato-Tainui • Mixed ownership of lake margins (Fish and Game, DoC, local Iwi, WRC, WDC, private) • Remainder of catchment upstream (mainly private) • Remainder of catchment downstream (DoC, Fish and Game, private)

  20. Governance Arrangements • Waikato District Council • Land use planning • Consent to discharge (Te Kauwhata waste water) • Waikato Regional Council • RMA - Effects of land use, Healthy Rivers – WaiOra, Water allocation V6 • Lower Waikato Liaison subcommittee • Lower Waikato Flood Protection Scheme and associated consents • Project Watershed – Integrated catchment management • Co-management (JMAs and co-managed lands)

  21. Governance Arrangements • Joint management • Co-management • Waikato District Lakes Memorandum of Agreement • Waikato Tainui • Co-governors and owners of lake bed • Co-managed lands / Sites of significance • DoC • Wetland and Biodiversity management • Fish and Game • Wetland and game bird management

  22. Future • Management of upper catchment (soil conservation and water quality) • Scale of issues major impediment to in-lake restoration • Habitat enhancement of margins – ephemeral wetlands • Management of lake depth – WQ/sediment re-suspension, irrigation • Plant pest management (yellow flag, alligator weed)

  23. Future • Management of the flood protection scheme • Local -1500 ha surrounding lake • Regional – 17,000 ha protected land • National infrastructure – SH1 protection • Lake Waikare an important part of the scheme • Challenge: • Maintaining viable flood protection scheme • Improving lake water quality • Protecting biodiversity • Managing future demands for water • All parties to act effectively towards a common goal

  24. WRC Future Actions • Consent review Lower Waikato Flood Control Scheme • Lake Waikare discharge • Impacts on Whangamarino wetland • Long Term Plan 2015-25 • Detailed assessment of high risk/opportunity sites in the zone • Project management for inter-agency catchment plan • Additional catchment management staff and incentives

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