Whängärei Harbour Water Quality Improvement Strategy November 2012 Prepared by Northland Regional Council and Whängärei District Council

Whängärei Harbour Water Quality Improvement Strategy November 2012 Prepared by Northland Regional Council and Whängärei District Council Cover image © Bee Scene Photography Table of contents Executive summary .................................................................................................................................................. 4 1 Introduction ...................................................................................................................................................... 5 1.1 Background .............................................................................................................................................. 5 1.2 Purpose of this strategy ...................................................................................................................... 6 1.3 Document structure .............................................................................................................................. 6 1.4 Integration with other initiatives ...................................................................................................... 6 1.4.1 Waiora Northland Water ........................................................................................................... 7 1.4.2 Whāngārei District Council Wastewater Management Strategy ................................ 7 2 The harbour and its catchment ................................................................................................................. 8 2.1 Overview.................................................................................................................................................... 8 2.1 Catchment description ........................................................................................................................ 9 2.1.1 Sub-catchments ......................................................................................................................... 11 2.2 Values and uses of the harbour .................................................................................................... 16 2.2.1 Ecology .......................................................................................................................................... 16 2.2.2 Recreation..................................................................................................................................... 25 2.2.3 Economic and municipal ......................................................................................................... 27 2.2.4 Maori cultural values ................................................................................................................ 27 2.3 Managing harbour water quality .................................................................................................. 30 2.3.1 Direct discharges ....................................................................................................................... 30 2.3.2 Diffuse discharges ..................................................................................................................... 32 3 Water quality in the harbour ................................................................................................................... 33 3.1 Current monitoring of the harbour .............................................................................................. 34 3.2 Water quality and the harbour ecosystem ................................................................................ 36 3.2.1 Sediments ..................................................................................................................................... 37 3.2.2 Sediment contamination ........................................................................................................ 40 3.2.3 Nutrients ....................................................................................................................................... 42 3.3 Water quality and human health .................................................................................................. 48 3.3.1 Contact recreation ..................................................................................................................... 50 3.3.2 Shellfish gathering .................................................................................................................... 59 3.4 Summary and considerations ......................................................................................................... 61 4 Key sources of contamination ................................................................................................................. 62 4.1 Urban wastewater ............................................................................................................................... 62 4.1.1 Whāngārei Wastewater Treatment Plant .......................................................................... 62 4.1.2 Network overflows and leakage .......................................................................................... 62 4.2 Urban stormwater ............................................................................................................................... 64 4.2.1 Stormwater quality .................................................................................................................... 68 4.2.2 Future pressures ......................................................................................................................... 69 4.2.3 Roads and walkways ................................................................................................................. 69 4.3 Pastoral activities and rural stormwater ..................................................................................... 70 4.3.1 Rural upper harbour sub-catchments ................................................................................ 71 4.3.2 Mixed land use upper harbour catchments .................................................................... 72 4.4 Farm dairy effluent ............................................................................................................................. 74 4.5 Forestry ................................................................................................................................................... 74 4.6 Urban development ........................................................................................................................... 75 1 4.7 Septic systems ...................................................................................................................................... 76 4.8 Parks and reserves .............................................................................................................................. 77 4.9 Boats ........................................................................................................................................................ 77 4.10 Harbour dredging ............................................................................................................................... 79 4.11 Industrial discharges .......................................................................................................................... 79 4.12 Landfills ................................................................................................................................................... 80 4.12.1 Quarries ......................................................................................................................................... 81 4.13 Summary and considerations ......................................................................................................... 81 5 Proposed water quality objectives for the harbour ........................................................................ 82 6 Actions and recommendations ............................................................................................................... 82 6.1 Overview................................................................................................................................................. 83 6.1.1 Direct discharges ....................................................................................................................... 83 6.1.2 Diffuse discharges ..................................................................................................................... 83 6.1.3 Integrated catchment management .................................................................................. 83 6.2 Detailed actions ................................................................................................................................... 87 6.2.1 Enforcement of and compliance with current regulation .......................................... 87 6.2.2 Undertaking, promoting, and supporting good/best management practices .. 88 6.2.3 Other .............................................................................................................................................. 91 6.2.4 Monitoring and research ........................................................................................................ 93 6.2.5 Improving the regulatory framework ................................................................................. 94 7 Conclusion ...................................................................................................................................................... 97 Appendix 1 – Whāngārei

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