Kopenui Stream Reservoir Assessment of Ecological Effects 24 April 2020 puhoistour.co.nz PUHOI STOUR LIMITED LYSAGHT BUILDING | 101 PAKENHAM STREET AUCKLAND 1010 Kopenui Stream Reservoir: Assessment of Ecological Effects Martin Neale, Puhoi Stour Limited Alicia Wong, Tonkin & Taylor Sam Heggie-Grace, Tonkin & Taylor Mike Lake, Tonkin & Taylor Justine Quinn, Tonkin & Taylor Prepared for Northland Regional Council by Puhoi Stour Ltd (Project 2019/026) and Tonkin & Taylor Ltd (Job number 1012828). This work was undertaken by Puhoi Stour Limited in accordance with a Short Form Agreement dated 30 August 2019. Tonkin and Taylor were engaged in accordance with a Letter of Engagement dated 11 March 2020 Document History PSL Report Number 2020/02 Version Date Reviewed by Draft for internal T&T review 25 March 2020 Justine Quinn First Draft for PSL review 28 March 2020 Martin Neale Second draft for internal T&T review 1 April 2020 Justine Quinn Trevor Connelly Second Draft for PSL review 1 April 2020 Martin Neale Draft for client review 2 April 2020 Martell Letica Final 8 April 2020 Martin Neale Justine Quinn Josh Markham PUHOI STOUR | PAGE 2 Table of Contents Table of Contents ........................................................................................................................................................................... 3 1. Introduction ............................................................................................................................................................................ 5 2. Site description ...................................................................................................................................................................... 5 3. Methods ................................................................................................................................................................................. 6 3.1 Desktop assessment .................................................................................................................................................... 6 3.2 Freshwater values assessment .................................................................................................................................... 7 3.2.1 Stream classifications .......................................................................................................................................... 7 3.2.2 Macroinvertebrates .............................................................................................................................................. 7 3.2.3 Fish ...................................................................................................................................................................... 8 3.2.4 Stream ecological valuation ................................................................................................................................. 8 3.3 Terrestrial values assessment .................................................................................................................................... 10 3.3.1 Ecosystem types ................................................................................................................................................ 10 3.3.2 Bats .................................................................................................................................................................... 10 3.3.3 Birds ................................................................................................................................................................... 10 3.3.4 Herpetofauna ..................................................................................................................................................... 10 3.3.5 Invertebrates ...................................................................................................................................................... 10 3.4 Assessment of effects................................................................................................................................................. 11 4. Freshwater ecological assessment ..................................................................................................................................... 11 4.1 Stream classification and values ................................................................................................................................ 11 4.1.1 Proposed reservoir location ............................................................................................................................... 11 4.1.2 Downstream of proposed reservoir .................................................................................................................... 13 4.1.3 Proposed water take site ................................................................................................................................... 14 4.2 Assessment of ecological effects - freshwater ............................................................................................................ 15 4.2.1 Sedimentation during construction ..................................................................................................................... 15 4.2.2 Injury or mortality of freshwater fauna ................................................................................................................ 15 4.2.3 Fish passage ...................................................................................................................................................... 16 4.2.4 Permanent modification of stream habitat .......................................................................................................... 17 4.2.5 Downstream water quality effects ...................................................................................................................... 19 4.2.6 Downstream habitat effects ............................................................................................................................... 19 5. Terrestrial and wetland ecological assessment ................................................................................................................... 20 5.1 Terrestrial flora............................................................................................................................................................ 20 5.1.1 Podocarp-broadleaf forest ................................................................................................................................. 20 5.1.2 Old-growth forest fragments .............................................................................................................................. 20 5.1.3 Secondary broadleaved shrub ........................................................................................................................... 21 5.1.4 Swamp forest ..................................................................................................................................................... 21 5.1.5 Exotic vegetation ........................................................................................................................................................ 21 PUHOI STOUR | PAGE 3 5.1.6 Raupō reedland .......................................................................................................................................................... 21 5.1.7 Carex wetland .................................................................................................................................................... 22 5.1.8 Exotic dominated wet areas ....................................................................................................................................... 22 5.1.9 Threatened plant species ........................................................................................................................................... 22 5.2 Terrestrial fauna.......................................................................................................................................................... 23 5.2.1 Bats .................................................................................................................................................................... 23 5.2.2 Avifauna ............................................................................................................................................................. 23 5.2.3 Herpetofauna ..................................................................................................................................................... 24 5.2.4 Invertebrates ...................................................................................................................................................... 24 5.3 Assessment of ecological effects - terrestrial.............................................................................................................. 25 5.3.1 Vegetation effects .............................................................................................................................................. 25 5.3.2 Fauna effects ..................................................................................................................................................... 27 5.3.3 Fauna effects management ..............................................................................................................................