Condition Assessment using 2016 River Habitat Survey data and Common Standards Monitoring guidance for the Afon Teifi and Afon Eden – Cors Goch Trawsfynydd SACs Baxter, E., McKenzie, S., Jones, D., Jones, C and Metcalfe, P. Ecus Ltd in association with TerrAqua Ecological Services Ltd NRW Evidence Report No. 192 Date www.naturalresourceswales.gov.uk About Natural Resources Wales Natural Resources Wales’ purpose is to pursue sustainable management of natural resources. This means looking after air, land, water, wildlife, plants and soil to improve Wales’ well-being, and provide a better future for everyone. We will realise this vision by: Maintaining and developing the technical specialist skills of our staff; Securing our data and information; Having a well resourced proactive programme of evidence work; Continuing to review and add to our evidence to ensure it is fit for the challenges facing us; and Communicating our evidence in an open and transparent way. This Evidence Report series serves as a record of work carried out or commissioned by Natural Resources Wales. It also helps us to share and promote use of our evidence by others and develop future collaborations. However, the views and recommendations presented in this report are not necessarily those of NRW and should, therefore, not be attributed to NRW. Evidence at Natural Resources Wales Natural Resources Wales is an evidence based organisation. We seek to ensure that our strategy, decisions, operations and advice to Welsh Government and others are underpinned by sound and quality-assured evidence. We recognise that it is critically important to have a good understanding of our changing environment. We will realise this vision by: Maintaining and developing the technical specialist skills of our staff; Securing our data and information; Having a well resourced proactive programme of evidence work; Continuing to review and add to our evidence to ensure it is fit for the challenges facing us; and Communicating our evidence in an open and transparent way. This Evidence Report series serves as a record of work carried out or commissioned by Natural Resources Wales. It also helps us to share and promote use of our evidence by others and develop future collaborations. However, the views and recommendations presented in this report are not necessarily those of NRW and should, therefore, not be attributed to NRW. www.naturalresourceswales.gov.uk Page 1 Report series: NRW Evidence Report Report number: 192 Publication date: February 2017 Contract number: ATI-11338a Contractor: Ecus Ltd Contract Manager: Dr Sue Hearn Title: Condition Assessment using 2016 River Habitat Survey data and Common Standards Monitoring guidance for the Afon Teifi and Afon Eden – Cors Goch Trawsfynydd SACs Author(s): Baxter, E., McKenzie, S., Jones, C., Jones, D. and Metcalfe, P. Technical Editor: Dr Phil Metcalfe Peer Reviewer(s) n/a Approved By: Nick Birkinshaw Restrictions: None Distribution List (core) NRW Library, Bangor 2 National Library of Wales 1 British Library 1 Welsh Government Library 1 Scottish Natural Heritage Library 1 Natural England Library (Electronic Only) 1 Distribution List (others) Phil Boon, SNH Heather Garrett, NRW Tristan Hatton-Ellis, NRW Arfon Hughes NRW Melissa Lacan, NRW Alison Lee, SNH Claire Liversage, NRW Chris Mainstone, NE Graham Rutt, NRW Angus Tree, SNH Jon Turner, NRW Tony Waterman, NIEA Nia Watkin NRW Jenny Wheeldon, NE SNH- Scottish Natural Heritage, NE- Natural England, NIEA- Northern Ireland Environment Agency Recommended citation for this volume: Baxter, E., McKenzie, S., Jones, C., Jones, D. and Metcalfe, P. 2017. Condition assessment using 2016 River Habitat Survey data and Common Standards Monitoring guidance for the Afon Teifi and Afon Eden – Cors Goch Trawsfynydd SACs. NRW Evidence Report No: 192, 95 pp. NRW, Bangor. www.naturalresourceswales.gov.uk Page 2 Contents 1. Crynodeb Gweithredol .................................................................................................... 6 2. Executive Summary ........................................................................................................ 7 3. Introduction ..................................................................................................................... 8 3.1. Background ........................................................................................................................... 8 3.2. Project Scope ........................................................................................................................ 8 3.3. Afon Teifi SAC and Afon Eden - Cors Goch Trawsfynydd SAC Overview ........................... 8 3.3.1. Afon Teifi SAC: Site Description ....................................................................................... 9 3.3.2. Afon Eden – Cors Goch Trawsfynydd SAC: Site Description .......................................... 9 4. Methodology ................................................................................................................. 11 4.1. Assessment Units ................................................................................................................11 4.2. Site Selection ......................................................................................................................11 4.3. Field Survey ........................................................................................................................13 4.3.1. River Habitat Survey .......................................................................................................13 4.3.2. Simplified Phase 1 Habitat Survey .................................................................................13 4.3.3. Negative Indicators (Invasive non-native species) .........................................................13 4.4. Data Analysis and Interpretation .........................................................................................13 4.4.1. Habitat Structure Assessment ........................................................................................14 Channel Planform ..........................................................................................................................14 Habitat Modification Score .............................................................................................................14 Bank Vegetation Naturalness ........................................................................................................15 Riparian Zone Vegetation Naturalness ..........................................................................................15 Woody Debris ................................................................................................................................15 In-channel Structures .....................................................................................................................15 4.4.2. Fine Sediment- Siltation .................................................................................................15 4.4.3. Negative Indicators- Alien/Locally Absent Species ........................................................15 4.5. RHS Considerations and Limitations ..................................................................................16 5. Field Survey Results ..................................................................................................... 17 6. Condition Assessment: Afon Teifi ................................................................................. 18 6.1. Overview .............................................................................................................................18 6.2. Habitat Structure .................................................................................................................18 6.2.1. Channel Planform ...........................................................................................................18 6.2.2. Habitat Modification ........................................................................................................22 6.2.3. Bank Vegetation Naturalness .........................................................................................27 6.2.4. Riparian Zone Naturalness .............................................................................................29 6.2.5. Woody Debris .................................................................................................................32 6.2.6. In-channel Structures .....................................................................................................35 6.3. Fine Sediment .....................................................................................................................39 6.4. Negative Indicators ..............................................................................................................42 6.5. Condition Assessment Discussion and Summary: Key Points for Afon Teifi ......................46 6.5.1. Overview .........................................................................................................................46 www.naturalresourceswales.gov.uk Page 3 6.5.2. Factors Influencing Condition Assessment Outcomes ...................................................47 6.6. Afon Teifi Recommendations ..............................................................................................49 7. Condition Assessment: Afon Eden ................................................................................ 50 7.1. Overview .............................................................................................................................50