REPORT Mitigation and Monitoring for the Stour and Orwell Estuaries SPA and Hamford Water SPA Annual Report 2015-2016 Client: Harwich Haven Authority Reference: I&B9Y0158R001F0.2 Status: 0.2/Final Date: 29 January 2019 Project related HASKONINGDHV UK LTD. 36 Park Row Leeds LS1 5JL Industry & Buildings VAT registration number: 792428892 email E royalhaskoningdhv.com W Document title: Mitigation and Monitoring for the Stour and Orwell Estuaries SPA and Hamford Water SPA Reference: I&B9Y0158R001F0.2 Status: 0.2/Final Date: 29 January 2019 Project name: HHA annual monitoring Project number: 9Y0158 Author(s): Matt Simpson Drafted by: Matt Simpson Checked by: Sian John Date / initials: 29th January 2019 / SAJ Approved by: Sian John Date / initials: 29th January 2019 / SAJ Classification Project related Disclaimer No part of these specifications/printed matter may be reproduced and/or published by print, photocopy, microfilm or by any other means, without the prior written permission of HaskoningDHV UK Ltd.; nor may they be used, without such permission, for any purposes other than that for which they were produced. HaskoningDHV UK Ltd. accepts no responsibility or liability for these specifications/printed matter to any party other than the persons by whom it was commissioned and as concluded under that Appointment. The integrated QHSE management system of HaskoningDHV UK Ltd. has been certified in accordance with ISO 9001:2015, ISO 14001:2015 and OHSAS 18001:2007. 29 January 2019 I&B9Y0158R001F0.2 i Project related Table of Contents 1 INTRODUCTION 1 1.1 This Report 1 1.2 Background 1 1.3 Objectives of compensation, mitigation and monitoring 2 1.4 Detailed objectives for compensation, mitigation and monitoring 4 1.4.1 Approach channel deepening 4 1.4.2 Trinity III Terminal (Phase 2) Extension 5 1.4.3 Monitoring 5 2 ONGOING ACTIVITIES 6 2.1 Introduction 6 2.2 Maintenance of Harwich Harbour: dredging and disposal 6 2.3 Approach channel deepening: habitat replacement 7 2.4 Approach channel deepening: sediment replacement 8 2.4.1 Stour estuary 8 2.4.2 Orwell estuary 9 2.4.3 Lower Harbour 10 2.5 Approach channel deepening: beneficial use schemes 10 2.6 Trinity III Terminal (Phase 2) Extension: disposal at sea 10 2.7 Trinity III Terminal (Phase 2) Extension: habitat enhancement 11 2.8 Trinity III Terminal (Phase 2) Extension: sediment replacement 11 2.9 Other activities and events 11 3 BATHYMETRIC AND TOPOGRAPHIC DATA 13 3.1 Intertidal and subtidal area and volume 13 3.1.1 Introduction 13 3.1.2 Orwell estuary 13 3.1.3 Stour estuary 14 3.2 Saltmarsh extent 14 4 BENTHIC INVERTEBRATE COMMUNITIES 17 4.1 Introduction 17 4.2 2015 annual benthic monitoring 17 4.3 Review of macrobenthic data for the monitoring period from 1997 to 2015 18 4.4 Distribution of marine invasive species in Harwich Haven 18 5 BIRD DISTRIBUTION AND ABUNDANCE 20 5.1 Background 20 29 January 2019 I&B9Y0158R001F0.2 ii Project related 5.1.1 Introduction 20 5.1.2 High water (core) counts 20 5.1.3 Low water counts 20 5.1.4 Waterbird distribution 20 5.1.5 WeBS Alerts 20 5.2 Analysis of waterbird data 20 5.3 High water count trends 21 5.3.1 Overview of Stour and Orwell estuaries populations 21 5.3.2 Analysis of key species 22 5.3.2.1 Introduction 22 5.4 Low water count trends 29 5.4.1 Introduction 29 5.4.2 Summary of the low water count data and trends 30 5.5 Assessment of changes in the Stour and Orwell estuaries in the context of national population trends 30 5.5.1 Dark-bellied Brent goose 31 5.5.2 Shelduck 31 5.5.3 Wigeon 32 5.5.4 Pintail 32 5.5.5 Oystercatcher 33 5.5.6 Ringed plover 33 5.5.7 Grey plover 34 5.5.8 Lapwing 34 5.5.9 Knot 35 5.5.10 Dunlin 35 5.5.11 Black-tailed godwit 36 5.5.12 Curlew 36 5.5.13 Redshank 37 5.5.14 Turnstone 37 5.6 Summary of trends from all data sources 38 5.7 Waterbird distribution 40 5.7.1 Introduction 40 5.7.2 Results 40 6 STOUR AND ORWELL CONDITION ASSESSMENT 43 7 COMPLETED MONITORING STUDIES 46 7.1 Trimley Marshes managed realignment monitoring 46 7.2 Trinity III Terminal habitat enhancement monitoring 46 8 SUMMARY AND CONCLUSIONS 47 8.1 Introduction 47 8.2 Bathymetric and topographic data 47 8.3 Benthic invertebrate communities 47 29 January 2019 I&B9Y0158R001F0.2 iii Project related 8.4 Bird distribution and abundance 48 8.5 Conclusion 48 9 References 50 Table of Tables Table 2.1 Number of deep drafted shipping movements at Felixstowe on an annual basis 7 Table 2.2 Water column recharge in the Stour Estuary 8 Table 2.3 Water column recharge in the Orwell Estuary 10 Table 2.4 Dredge disposal returns for quantity of material deposited in the River Orwell 12 Table 3.1 Orwell estuary intertidal volume and area between 0m CD and +4m CD 13 Table 3.2 Orwell estuary subtidal volume and area below 0m CD 13 Table 3.3 Stour estuary intertidal volume and area between 0m CD and +4m CD 14 Table 3.4 Stour estuary subtidal volume and area below 0m CD 14 Table 3.5 Summary of change in saltmarsh extent between 2005, 2010 and 2015 16 Table 5.1 Trends in the mean and peak numbers of species on the Orwell, Stour and SPA (1999/2000 to 2015/2016) Colours denote an increasing (green) or decreasing (red) population and colour intensity indicates trend confidence (weak, medium or high); reproduced from Suffolk Wildlife Trust Trading Co, 2016) 30 Table 5.2 Summary of national and SPA population trends for key waterbird species 39 Table of Figures Figure 1.1 Study area 3 Figure 2.1 Illustration of current placement strategy 9 Figure 3.1 Overview of erosion and accretion patterns between 2005 and 2015 in the Orwell and Stour estuaries 15 Figure 5.1 The features and place names of the Stour and Orwell estuaries at low tide 21 Figure 5.2 Total number of waterbirds on the Stour and Orwell estuaries (data sourced from Frost et al., 2017) 22 Figure 5.3 Numbers of dark-bellied Brent goose (2011/12 to 2015/16) 23 Figure 5.4 Numbers of shelduck (2011/12 to 2015/16) 23 Figure 5.5 Numbers of wigeon (2011/12 to 2015/16) 24 Figure 5.6 Numbers of pintail (2011/12 to 2015/16) 24 Figure 5.7 Numbers of oystercatcher (2011/12 to 2015/16) 25 Figure 5.8 Numbers of ringed plover (2011/12 to 2015/16) 25 Figure 5.9 Numbers of grey plover (2011/12 to 2015/16) 26 29 January 2019 I&B9Y0158R001F0.2 iv Project related Figure 5.10 Numbers of lapwing (2011/12 to 2015/16) 26 Figure 5.11 Numbers of knot (2011/12 to 2015/16) 27 Figure 5.12 Numbers of dunlin (2011/12 to 2015/16) 27 Figure 5.13 Numbers of black-tailed godwit (2011/12 to 2015/16) 28 Figure 5.14 Numbers of curlew (2011/12 to 2015/16) 28 Figure 5.15 Numbers of redshank (2011/12 to 2015/16) 29 Figure 5.16 Numbers of turnstone (2011/12 to 2015/16) 29 Figure 5.17 The mean (± SEs) (left) and peak (right) numbers of dark-bellied Brent goose on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 31 Figure 5.18 The mean (± SEs) (left) and peak (right) numbers of shelduck on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 32 Figure 5.19 The mean (± SEs) (left) and peak (right) numbers of wigeon on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 32 Figure 5.20 The mean (± SEs) (left) and peak (right) numbers of pintail on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 33 Figure 5.21 The mean (± SEs) (left) and peak (right) numbers of oystercatcher on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 33 Figure 5.22 The mean (± SEs) (left) and peak (right) numbers of ringed plover on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 34 Figure 5.23 The mean (± SEs) (left) and peak (right) numbers of grey plover on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 34 Figure 5.24 The mean (± SEs) (left) and peak (right) numbers of knot on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 35 Figure 5.25 The mean (± SEs) (left) and peak (right) numbers of dunlin on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 36 Figure 5.26 The mean (± SEs) (left) and peak (right) numbers of black-tailed godwit on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 36 Figure 5.27 The mean (± SEs) (left) and peak (right) numbers of curlew on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 37 29 January 2019 I&B9Y0158R001F0.2 v Project related Figure 5.28 The mean (± SEs) (left) and peak (right) numbers of redshank on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 37 Figure 5.29 The mean (± SEs) (left) and peak (right) numbers of turnstone on the Orwell (●), Stour (○) and whole SPA (■) in winters 1999-2000 (0) to 2015/2016 (16) (source: Suffolk Wildlife Trust Trading Co, 2016) 38 Figure 5.30 Trends in winter section populations