River Wensum Restoration Strategy Implementation SSSI Unit 51 Mill to Mill

FEASIBILITY & ENVIRONMENTAL SCOPING ASSESSMENT

May 2012

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

River Wensum Restoration Strategy

Implementation SSSI Unit 51

North Elmham Mill to Elsing Mill Feasibility & Environmental Scoping Assessment

May 2012 Notice

This report was produced by Atkins for the Environment Agency for the specific purpose of assessing the feasibility of restoring favourable condition to the River Wensum SSSI. This report may not be used by any person other than the Environment Agency without Environment Agency express permission. In any event, Atkins accepts no liability for any costs, liabilities or losses arising as a result of the use of or reliance upon the contents of this report by any person other than the Environment Agency. Document History

JOB NUMBER: 5078052/60/099 DOCUMENT REF: 5078052/60/099 Revision Purpose Description Originated Checked Reviewed Authorised Date V0.1 Initial Draft Ian Morrissey RAC KS V0.1 Draft for client review IPM / AP / RAC / KLC / IPM KS RAC 06/04/2011 JG / NS V1 Final for issue IPM / AP / RAC / KLC / IPM KS DR 16/05/2012 JG / NS

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

Contents Section Page Non Technical Summary 1 1. Introduction 3 1.1 Context 3 1.2 River Wensum Restoration Strategy 7 1.3 Feasibility Assessment aims 9 1.4 Methodology 9 2. North Elmham Mill to Elsing Mill Overview 12 2.1 Terminology and site location 12 2.2 Previous works within Unit 51 14 2.3 RWRS restoration vision for Unit 51 14 3. Environmental Baseline 16 3.1 Introduction 16 3.2 Common environment features across all reaches 17 3.3 Environmental baseline for each reach within Unit 51 31 4. Consultation 57 4.1 Introduction 57 4.2 Consultation with key stakeholders 57 4.3 Drop-in session September 2009 59 4.4 Future consultation 59 5. Multi-Criteria Analysis Options Appraisal 61 5.1 Introduction 61 5.2 Constructing the MCA tool 61 5.3 Using the MCA Tool 67 6. Developing Conceptual Design 75 6.1 Introduction and approach 75 6.2 Description of River Restoration and Targeted Maintenance options 75 6.3 Reach 14: Elsing Reach 83 6.4 Reach 15: Reach 95 6.5 Reach 16: Elmham Reach 100 7. Cost Estimate 105 7.1 Previous cost estimates 105 7.2 Present cost estimates 106 7.3 Potential cost savings 108 7.4 Delivery 111 7.5 Summary 112 8. Environmental Scoping 115 8.1 Introduction 115 8.2 Method of assessment 117 8.3 Results of scoping 118 9. Consents 125 10. Project Risks 127

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11. Conclusions and Recommendations 129 11.1 Conclusions 129 11.2 Recommendations 130 12. References 131 Appendices 133 Appendix A – Multi-Criteria Analysis Technical Note Appendix B – Costings Appendix C – Ecology tables Appendix D – Terrestrial SSSI unit links to River Wensum SSSI units List of Figures Figure 1.1- Unit 51 River Wensum location plan 4 Figure 1.2 – Environmental and restoration related investigations and events, showing how this assessment fits within the process of realising restoration on the River Wensum 6 Figure 1.3 - The approach adopted during feasibility assessment for determining the recommended restoration option on individual reaches and the overall river unit 10 Figure 2.1 - Location of Reaches 14 to 16 within Unit 51 13 Figure 3.1 - Environmental constraints on Unit 51 27 Figure 3.2 – Environmental baseline for Reach 14 (Elsing Reach) 34 Figure 3.3 – Environmental baseline for Reach 15 (Swanton Morley Reach) 38 Figure 3.4 – Environmental baseline for Reach 16 (Elmham Reach) 42 Figure 6.1 - Location of sub-reaches within Reach 14 (Elsing Reach) 91 Figure 6.2 - Conceptual restoration plan for Reach 14a (Elsing Reach: Swanton Morley Mill structures to Hillhouse Farm) 92 Figure 6.3 - Conceptual restoration plan for Reach 14b (Elsing Reach: Hillhouse Farm to Penny Spot Beck)93 Figure 6.4 - Conceptual restoration plan for Reach 14c (Elsing Reach: Penny Spot Beck to Elsing Mill) 94 Figure 6.5 - Conceptual restoration plan for Reach 15 (Swanton Morley Reach) 99 Figure 6.6 - Conceptual restoration plan for Reach 16 (Elmham Reach) 104 Figure 8.1 - Environmental scoping within the EIA process 116

List of Tables Table 1.1 - Chapters constituting this report 7 Table 2.1 - Summary of previous restoration works consented on Unit 51 14 Table 2.2 - Recommended restoration measures for each reach as provided in the RWRS (JBA, 2007) 15 Table 3.1 - Mill details in Unit 51 (Environment Agency, 2007a) 24 Table 3.2 - WFD quality assessment (Environment Agency, 2010b) 25 Table 3.3 - Condition summary of Unit 51 attributes (Natural , 2010) 26 Table 3.4 - Baseline information common to Unit 51 28 Table 3.5 - Baseline information specific to Reach 14 (Elsing Reach) 31 Table 3.6 - Baseline information specific to Reach 15 (Swanton Morley Reach) 35 Table 3.7 - Baseline information specific to Reach 16 (Elmham Reach) 39 Table 4.1 - Consultation undertaken to date (August 2010) 57 Table 5.1 - Overview of the process by which the MCA was constructed and applied 61 Table 5.2 - Restoration measures recommended in previous studies 62 Table 5.3 - Options identified for restoration on the River Wensum 63 Table 5.4 - Description of river restoration measures as defined under option G5 64 Table 5.5 - Criteria defined for the MCA 66 Table 5.6 - Scoring system defined for the Multi-Criteria Analysis 67

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Table 5.7 - Results of MCA for Reach 14 (Elsing Reach) 69 Table 5.8 - Results of MCA for Reach 15 (Swanton Morley Reach) 70 Table 5.9 - Results of MCA for Reach 16 (Elmham Reach) 71 Table 5.10 - Summary of favourable options and measures for Unit 51 74 Table 6.1 - Different management classes of restoration activity 76 Table 6.2 - Active and passive river restoration measures 76 Table 6.3 - River restoration measures and their potential ecological benefits 79 Table 6.4 - The effect of river restoration measures according to flow condition 81 Table 6.5 – Key characteristics of Reach 14 sub-reaches 83 Table 6.6 - Significant features and possible measures observed for Reach 14 during site visit (January, 2010) 84 Table 6.7 - Review of strategy objectives and recommendations for Reach 14 85 Table 6.8 - Recommended restoration options for Reach 14 87 Table 6.9 – Restoration measure suitability rating for Reach 14 sub-reaches 88 Table 6.10 - Significant features and possible measures observed for Reach 15 during site visit (January, 2010) 95 Table 6.11 - Review of strategy objectives and recommendations for Reach 15 96 Table 6.12 - Recommended restoration options for Reach 15 97 Table 6.13 - Significant features and possible measures observed for Reach 16 during site visit (January, 2010) 100 Table 6.14 - Review of strategy objectives and recommendations for Reach 16 101 Table 6.15 - Recommended restoration options for Reach 16 102 Table 7.1 - RWRS Unit 51 cost estimate (JBA, 2007) 105 Table 7.2 - Halcrow PSA Unit 51 cost estimate 106 Table 7.3 - Comparison of cost estimates between JBA and Halcrow reports for Unit 51 106 Table 7.4 - Unit 51 cost estimates for various river restoration measures (January 2012) 107 Table 7.5 – Unit 51 cost estimates for each reach and restoration measure 108 Table 7.6 - Options that typically generate or require spoil 109 Table 7.7 - Gravel substitution using surplus fill 110 Table 7.8 – Recommended phasing of works 111 Table 7.9 - Recommended phasing of restoration measures for Unit 51 113 Table 7.10 - Comparison of costs between 2007, 2008 and 2011 studies 114 Table 8.1 - Classifying and evaluating the significance of potential environmental effects in the scoping process (adopted from European Commission, 2001) 117 Table 8.2- Environmental scoping assessment for recommended restoration options 119 Table 8.3 - Issues scoped into the EIA process 123 Table 8.4 - Issues scoped out of the EIA process 124 Table 9.1 - Likely planning consents and permissions 125 Table 10.1 – Key project risks that may delay the delivery of the recommended options for Unit 51 128

List of Plates Plate 1 – Site of Swanton Morley Mill showing fixed weir on main channel at site of mill (TG 02050 18479, January 2011) 22 Plate 2 – Site of Swanton Morley Mill showing weir on bypass channel (TG 02205 18691) 22 Plate 3 – View of 2 Arch (left) and 3 Arch (right) bridges at Swanton Morley 22 Plate 4 – View of Elsing Mill (TG 05000 17683) showing vertical lifting gates on bypass channel in foreground 23 Plate 5 – Reach 14: River Wensum looking downstream to 3 Arch Bridge below site of Swanton Morley Mill (NGR TG 02045 08468, January 2011) 43

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Plate 6 – Reach 14: Bypass channel at 2 Arch Bridge below site of Swanton Morley Mill (NGR TG 02150 18503, January 2011) 43 Plate 7 – Reach 14: Confluence of main channel and bypass channel downstream of Swanton Morley bridges (NGR TG 02035 18348, January 2011) 43 Plate 8 – Reach 14: Downstream view showing large berm development on TLHB (NGR TG 02049 18160, January 2011) 44 Plate 9 – Reach 14: Field drain junction with the River Wensum (NGR TG 02089 18036, January 2011) 44 Plate 10 – Reach 14: Riparian woodland showing secondary channel confluence with primary flow route (NGR TG 02202 17707, January 2011) 44 Plate 11 – Reach 14: Spring fed channel, one of many discharging at this location (NGR TG 02406 17593) 45 Plate 12 – Reach 14: High embankments at Castle Farm showing perched river channel (NGR TG 02739 17707, January 2011) 45 Plate 13 – Reach 14: General character of IDB drain on TLHB floodplain (NGR TG 03271 18201, January 2011) 45 Plate 14 – Reach 14: Wensum valley viewed towards the south-east from Lime Kiln Road (NGR TG 03542 18379, January 2011) 46 Plate 15 – Reach 14: Penny Spot Beck confluence (NGR TG 04195 17528, January 2011) 46 Plate 16 – Reach 14: Phalaris berm on approach to overhanging tree cover on TLHB below Old Hall Farm (NGR TG 04124 17788, January 2011) 46 Plate 17 – Reach 14: Significant enlargement of channel width on approach to Elsing Mill (NGR TG04398 17320, January 2011) 47 Plate 18 – Reach 14: View of island showing secondary channel confluence downstream of meander bend (NGR TG 04823 17482, January 2011) 47 Plate 19 – Reach 14: Sluice on Elsing Mill bypass channel with vertical lift gates fully open (NGR TG 04939 17595, January 2011) 47 Plate 20 – Reach 14: Bypass channel out of bank event downstream of sluice with inundated floodplain in background (NGR TG 04920 17607, January 2011) 48 Plate 21 – Reach 14: Approach to Elsing Mill with bypass sluice to the left of picture (NGR TF 04943 17592, November 2010) 48 Plate 22 – Reach 15: Recent ditch clearance work on TLHB floodplain (NGR TG 00767 19668, January 2011) 48 Plate 23 – Reach 15: Downstream view from river crossing at Riverside Farm (NGR TG 00797 19552, January 2011) 49 Plate 24 – Reach 15: Fish fry bay completed in 2005 opposite Burgh Common (NGR TG 01047 19445, January 2011) 49 Plate 25 – Reach 15: Fishing platforms and boardwalk at Burgh Common (NGR TG 01321 19316, January 2011) 49 Plate 26 – Reach 15: Downstream view showing gravel pit lake on TLHB floodplain and approximate location of in-stream gravel works undertaken in 2005 on the River Wensum (NGR TG 01592 19340, January 2011) 50 Plate 27 – Reach 15: River Wensum (foreground) and pit lake (background) showing limited freeboard at time of visit (NGR TG 01910 19394, January 2011) 50 Plate 28 – Reach 15: Sandbag line to protect against breach of River Wensum into adjacent fishing lakes on TRHB floodplain (NGR TF 97518 25868, November 2010) 50 Plate 29 – Reach 15: View across valley towards IDB channel on TLHB floodplain (NGR TG 02171 19072, January 2011) 51 Plate 30 – Reach 15: Approximate location of fry refuge created in 2006 (NGR TG 02167 18898) 51 Plate 31 – Reach 15: Upstream view of River Wensum from below bypass channel off-take and weir (NGR TG 02185 18687, January 2011) 51 Plate 32 – Reach 15: Bypass channel weir and confluence of IDB channel on right (NGR TG 02215 18653, January 2011) 52 Plate 33 – Reach 16: North Elmham Mill bypass channel (NGR TG 00321 20381, January 2011) 52

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Plate 34 – Reach 16: Main river and bypass confluence downstream of mill (NGR TF 98201 25222, November 2010) 52 Plate 35 – Reach 16: View towards Billingford Road bridge showing Glyceria berm development on both banks (NGR TG 00485 20308, January 2011) 53 Plate 36 – Reach 16: IDB channel and main river confluence immediately upstream of Billingford Road bridge (TG 00448 20187, January 2011) 53 Plate 37 – Reach 16: Downstream view towards old road bridge crossing (removed) (NGR TG 00453 20120, January 2011) 53 Plate 38 – Reach 16: Black Water / Wendling Beck confluence (NGR TG 00527 20055, January 2011) 54 Plate 39 – Reach 16: Black Water / Wendling Beck (NGR TG 00527 20055, January 2011) 54 Plate 40 – Reach 16: Mature berm feature on TRHB (NGR TG 00656 20054, January 2011) 54 Plate 41 – Reach 16: Site of bank erosion of TRHB viewed upstream (NGR TG 00527 20055, January 2011)55 Plate 42 – Reach 16: Billingford meander loop reconnection (NGR TG 00697 19998, January 2011) 55 Plate 43 – Reach 16: Downstream view towards reach boundary location (Reach 16/15) (NGR TG 00697 19998, January 2011) 55 Plate 44 – Reach 15: River Wensum viewed downstream towards Riverside Farm (NGR TG 00740 19807, January 2011) 56 Plate 45 – River alteration continuum 75

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

Abbreviations

Acronym Meaning

AOD Above Ordnance Datum

BAP Biodiversity Action Plan

BDC Council

CWD Coarse Woody Debris (term used in RWRS for LWD)

CWS County Wildlife Sites

EIA Environmental Impact Assessment

ECSFDI England Catchment Sensitive Farming Delivery Initiative

ESA Environmentally Sensitive Area

GPDO General Permitted Development Order

GQA General Quality Assessment

IDB Internal Drainage Board

JNCC Joint Nature Conservation Committee

KLWNDC King’s Lynn and West District Council

LWD Large Woody Debris

MCA Multi-Criteria Analysis

NCC

NNDC District Council

PIT Passive Integrated Transponder

PSA Public Service Agreement

RCS River Corridor Survey

RBMP River Basin Management Plan

RWRS River Wensum Restoration Strategy

RRC River Restoration Centre

SAC Special Area of Conservation

SI Statutory Instrument

SSSI Site of Special Scientific Interest

STW Sewage Treatment Works

TLHB True Left Hand Bank

TRHB True Right Hand Bank

TWS Total Weighted Score

WFD Water Framework Directive

WLMP Water Level Management Plan

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

Non Technical Summary

Introduction This feasibility and environmental scoping report identifies river restoration options that could be implemented to restore Unit 51 (North Elmham Mill to Elsing Mill) of the River Wensum Site of Special Scientific Interest (SSSI) to ‘unfavourable recovering’ or ‘favourable’ ecological condition. To achieve this aim, a range of specific technical, economic, environmental and social objectives need to be met. Objective The primary objective is to identify a range of restoration options to deliver physical modifications that will improve the ecological condition of the River Wensum. If river alterations are not implemented there remains a risk that the Government Public Service Agreement (PSA) target for SSSI condition will not be met and the river will not be returned from its current ‘unfavourable no change status’ to ‘unfavourable recovering’ or ‘favourable’ ecological condition. This report leads on from the River Wensum Restoration Strategy by assessing all river management options, including river restoration, in a transparent manner to demonstrate to stakeholders that all options for improving the SSSI condition of the River Wensum were considered. A key outcome of this report is the development of a conceptual design for the recommended restoration option. The River Wensum is also designated as a “Protected Area” under the European Union’s Water Framework Directive. An objective of the Anglian River Basin Management Plan is to improve the river from its current status of bad ecological potential to good ecological potential by 2027. Measures to meet this objective include large scale habitat improvements, such as removing impoundments on the river, restoring gravel beds, narrowing the channel, increasing the amount of large woody material and modifying the weed cutting regime at critical phases of fish life cycles. Consultation Extensive public and private land owner consultation was undertaken in September 2009 regarding management and restoration of the River Wensum for Unit 51. Consultation was in the form of a public drop in day at Race Course and submission of feedback forms from the public. The Environment Agency communicated with riparian landowners, and organisations including Natural England, Norfolk County Council, Breckland District Council, the Norfolk Rivers Internal Drainage Board, Norfolk Wildlife Trust and water recreation groups including anglers and canoeists. Initial input from these organisations suggests strong support for implementing restoration options and any other wider environmental enhancements. However a minority remain convinced that more regular maintenance, including dredging, as well as the retention of the impoundments behind mills, is the key to improving river health. Options for restoration A Multi-Criteria Analysis (MCA) was applied across a range of strategic river management / restoration options. The MCA allowed the appraisal of all options individually, and against each other, for their technical, economic and environmental constraints and opportunities. This provided an objective and transparent method for determining the most suitable restoration option for improving the SSSI condition. The result of the MCA for this river unit showed that our recommended option is likely to be a combination of river restoration works and targeted maintenance. This may also involve changing the retained water level at the site of Swanton Morley Mill and at Elsing Mill and re-evaluating the current maintenance regime. A conceptual design for river restoration and targeted maintenance has been developed and this can be applied across the entire unit, at a reach level or at a more discrete ‘section’ level.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

Costs Indicative costs for implementing the preferred river restoration option have been developed based on a per unit length of the main river channel. The estimated cost (to the nearest thousand) of the recommended options for this unit is £731,000. Cost savings have been explored through the re-use of previously excavated spoil to raise the river bed, reducing the extent of certain measures without compromising their function, using locally sourced materials and phasing the work efficiently. Environmental Scoping A high level environmental scoping appraisal has been undertaken against the potential restoration options. The result of this assessment has enabled environmental criteria to be scoped in or out of the Environmental Impact Assessment (EIA) process. In addition, key environmental constraints and opportunities have been identified that will require supplementary appraisal during detailed design of restoration projects.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

1. Introduction 1.1 Context

1.1.1 River Wensum The River Wensum is a low gradient chalk river located in Norfolk, England (see Figure 1.1). The river, and a number of adjacent floodplain land parcels, are of national and international importance for wildlife, being designated as a Site of Special Scientific Interest (SSSI) and as a Special Area of Conservation (SAC). As a chalk river the Wensum is also recognised as a priority habitat within the UK Biodiversity Action Plan (BAP). Past physical modifications to the River Wensum and tributaries have been undertaken to drain adjacent lands to improve their agricultural value, and to provide water storage for milling. These modifications have included extensive dredging which has straightened and over-deepened the channel, significantly impacting on the natural geomorphology and ecology of the river. The 14 redundant mill structures along the course of the River Wensum have significant hydrological impounding effects, with river water backing up behind these structures under a range of flows. This results in sluggish flows and accumulation of sediment in the channel, which, over time, have also contributed to the River Wensum being in unfavourable condition. The latest condition assessment of the SSSI (Natural England, 2010) found all of the riverine SSSI units to be in ‘unfavourable no change’ condition. Reasons cited for this condition include poor water quality, excessive siltation and physical modifications. Physical modifications of the river, and to some extent siltation, will be addressed through a programme of river restoration measures designed to help return the river to ‘unfavourable recovering’ or ‘favourable’ ecological condition. This Feasibility Report considers various options and measures by which this restoration can be achieved. Issues of poor water quality are being addressed at a strategic level through other projects such as the England Catchment Sensitive Farming Delivery Initiative (ECSFDI) and a review of existing abstraction licences and discharge consents. The Anglian River Basin Management Plan (RBMP) produced by the Environment Agency as required under the EU Water Framework Directive (200/60/EC) identifies the River Wensum upstream of Norwich as a heavily modified water body with bad ecological potential. The river’s bad ecological potential is attributed partly to its hydromorphological limitations resulting from historic alterations and unsympathetic management. The River Basin Management Plan includes a programme of measures, including river restoration, to improve the ecological condition of the river.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

Figure 1.1- Unit 51 River Wensum location plan

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

1.1.2 Feasibility Report This report continues the work commenced through the River Wensum Restoration Strategy (RWRS) (JBA, 2007), and represents the next step in the implementation of restoration. It defines a preferred restoration approach for Unit 51 (North Elmham Mill to Elsing Mill). The outcomes of this feasibility report will inform the detailed design and implementation of river restoration for this section of channel. The feasibility assessment continues the partnership between the Environment Agency and Natural England (formerly English Nature). It relates specifically to Unit 51 (River Wensum, North Elmham Mill to Elsing Mill) and the three ‘reaches’, 14, 15 and 16, which fall within this unit (see Section 2.1 for definitions of the terms ‘reach’ and ‘unit’). Figure 1.2 illustrates where this feasibility assessment fits within the planning of restoration on the River Wensum. The unit is approximately 8.5km in length and delineated upstream by North Elmham Mill and downstream by Elsing Mill. Feasibility reports are available as separate documents for the following river SSSI units:  Unit 46 River Tat  Unit 47 Tatterford Common to Fakenham Mill  Unit 48 Fakenham Mill to Great Ryburgh Mill  Unit 49 Great Ryburgh Mill to Elsing Mill  Unit 50 Mill to North Elmham Mill  Unit 52 Elsing Mill to Lenwade Mill  Unit 53 Lenwade Mill to Taverham Mill  Unit 54 Taverham Mill to Hellesdon Mill.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

An ecological survey (Holmes, 1980) of the river established that plant communities present in 1980 Ecological survey the upper reaches were typical of chalk rivers. This survey was repeated in 2002 (Grieve et al., 2002).

The Wensum Valley Countryside Management Project was established in 1988 as a joint venture between the Countryside Commission and local authorities. The objectives of the 1988 Wensum Valley Countryside Management Project project included the enhancement of wildlife habitats, landscape and recreational value of the valley.

The entire river was notified as a SSSI in February 1993, as an example of an enriched 1993 SSSI designation calcareous lowland river. The citation describes it as “probably the best whole river of its type in nature conservation terms”.

The Wensum Valley Strategy was published in 1994 by the Wensum Valley Project to provide Wensum Valley Strategy 1994 a framework for taking the project objectives forward and defines policies for future management of the valley.

The River Rehabilitation Feasibility Study of the River Wensum by Econ represented the first River Rehab WLMP 1999 specific review of restoration options for the River Wensum. In 1999, the first Water Level Feas Study Management Plan for the Wensum was also produced.

The Wensum Valley Project hosted a meeting between the Environment Agency, English 2002 Wensum Forum Nature and local landowners / IDB members.

A condition assessment of the SSSI unit was undertaken by English Nature (now Natural SSSI Condition Assessment 2002 England) and concluded that the river was in ‘unfavourable declining’ condition due mainly to water impoundment caused by physical structures (e.g. mills), siltation and water quality.

2004 - Geomorphological appraisal of the Geodata Services assessed the form and function of the river, and provided reach-based

2005 River Wensum SAC guidance on the management required to restore the natural geomorphology.

Wensum Fisheries Action Plan The Wensum Fisheries Action Plan group identified the need to fund and implement further 2004 habitat restoration schemes on the river to aid the sustainable recovery of fish stocks

This steering group was convened in order to consider the outcomes of the geomorphological English Nature Steering Group 2005 appraisal and to determine a way forward for improving the condition of the SSSI through river convened restoration.

Qualifying features for the SAC designation are white-clawed crayfish, Desmoulin’s whorl snail, 2005 SAC designation confirmed brook lamprey, bullhead and water crowfoot vegetation communities This revision of the previous Water Level Management Plan (1999) provides a framework for Water Level Management Plan, managing appropriate water levels, and was driven largely by the need to achieve nature 2007 River Wensum SSSI conservation objectives. Recommendations related to promoting agri-environment schemes and modifying impounding mill structures.

The River Wensum Restoration Strategy (RWRS) was completed by JBA in November 2007 River Wensum Restoration for Natural England, and represents a culmination of much of the previous work. This strategy 2007 Strategy considered the entire River Wensum but identified a range of high level river restoration options on a reach by reach basis.

Condition assessment of the SSSI unit was undertaken by Natural England and concluded that the river was in ‘unfavourable no change’ condition. Reasons cited for the condition include 2010 SSSI Condition Assessment water abstraction, water pollution from agriculture / run off and discharges, inappropriate water levels and inappropriate weirs, dams and other structures.

Feasibility Report: Unit 51 – North This report considers a number of restoration options specifically for Unit 51 and recommends the preferred restoration measure, or suite of measures, for each reach within the unit. The Elmham Mill to Elsing Mill report makes recommendations as to which of these measures should be progressed to 2011

Present achieve improvement for the unit as a whole. Future Outline and Detailed design of The detailed design of the recommended measures will be undertaken and associated consent applications (e.g. Flood Defence Consent) will be made. recommended options for the unit An environmental assessment of the proposed scheme will be undertaken

Future Construction River restoration measures will be constructed. Future Monitoring Monitoring of the effectiveness of the constructed measures will be on-going.

Figure 1.2 – Environmental and restoration related investigations and events, showing how this assessment fits within the process of realising restoration on the River Wensum

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

1.1.3 Structure of this report This report has been structured to reflect the sequential process by which the recommended restoration options have been determined. Table 1.1 lists the report chapters and provides a brief description of their contents. Table 1.1 - Chapters constituting this report

Chapter Title Description This chapter presents the context of the River Wensum, and 1 Introduction introduces the RWRS. It also discusses the methodology used in this report. Chapter 2 introduces the specific section of river considered in this North Elmham Mill to report, namely Unit 51, discussing location, previous restoration 2 Elsing Mill Overview initiatives, and those restoration measures recommended by the RWRS. Chapter 3 provides an overview of the environmental baseline for 3 Environmental Baseline the unit. It is provided on a reach by reach basis, focusing on reach- specific information. Chapter 4 provides details of the consultation process undertaken 4 Consultation as part of this feasibility assessment, and the main issues raised. Chapter 5 presents the Multi-Criteria Analysis explaining the 5 Options Appraisal methodology and those options which scored highest for each reach. Chapter 6 presents a conceptual design for the recommended Developing Conceptual 6 restoration measures for each reach based on results from the Multi- Design Criteria Analysis. Chapter 7 provides an estimate of costs for the preferred restoration 7 Cost Estimates option and identifies potential cost saving efficiencies in materials and phasing of the proposed works. The specific restoration plan proposed for the unit is subjected to an environmental scoping process. This determines the key 8 Environmental Scoping environmental issues to be considered in the environmental assessment. Chapter 9 discusses the consents that would be required prior to 9 Consents construction of the restoration works. This chapter tables the key project risks associated with the 10 Project Risks planning and implementation of the project. Conclusions and Chapter 11 concludes the report with recommendations for taking 11 Recommendations the project forward.

1.2 River Wensum Restoration Strategy The project was initiated in response to a number of key drivers. The most significant of these are listed below.  The Government’s Public Service Agreement (PSA) target for SSSIs constitutes the main driver for physical restoration of the river, and hence the main driver behind the RWRS. River restoration on the Wensum will contribute to the national target of 95% (by area) of SSSIs being in ‘favourable’ or ‘unfavourable recovering’ condition by 31 December 2010. All riverine units within the Wensum SSSI are currently in ‘unfavourable no change’ condition.  As a European Natura 2000 site, measures are required to ensure that the River Wensum moves towards ‘favourable’ conservation status. The European features of the site are; bullhead, brook lamprey, Desmoulin’s whorl snail, white-clawed crayfish and water crowfoot plant communities.  The River Basin Management Plan (RBMP) prepared for the Anglian River Basin District as required by the Water Framework Directive identifies the River Wensum upstream of Norwich as a heavily modified water body currently with Bad overall Potential. The RBMP sets objectives for the water body to reach Good Ecological Potential by 2027 and Good Chemical Status by 2015 and the RWRS is cited as a key action necessary to deliver the measures Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 7

River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

required for the River Wensum to meet these objectives. Measures include large scale habitat improvements to address those factors limiting natural hydromorphological functioning of the river and to restore favourable conditions for a range of fish species. Proposed actions cited by the RBMP for the River Wensum protected area include reducing impoundments on the river, restoring the gravel beds, narrowing the channel, increasing the amount of in-stream woody material and modifying the weed cutting regime at critical phases of fish life cycles.  Chalk rivers are a priority BAP habitat, with England supporting 85% of the world resource. The Environment Agency is the lead authority for this habitat, and objectives are defined in the Chalk River Habitat Action Plan produced jointly by the Environment Agency and Natural England. The Action Plan recognises the quality and importance of chalk rivers ecologically, hydrologically, recreationally and culturally (Environment Agency / Natural England, 2004).  River restoration will also contribute to the objectives of the River Wensum Fisheries Action Plan, River Wensum Water Level Management Plan (Environment Agency, 2007a) and Rivers Catchment Flood Management Plan. 1.2.1 Approach The RWRS report provided comprehensive high level guidance for restoration of the River Wensum. The chief aim of the strategy was to provide a whole river vision for implementation of restoration by developing restoration delivery plans on a reach by reach basis throughout the SSSI. The undertaking of the RWRS involved, amongst others, the following key activities:  Reviewing of existing baseline information.  Consulting with steering group members including the River Restoration Centre (RRC), as well as with key local stakeholders.  Reviewing the river reaches and restoration measures proposed in the Geomorphological Appraisal.  Mapping current conditions on the River Wensum and comparing them to expected semi- natural conditions in Norfolk.  Determining a cost-band for each of the RWRS reaches. The above culminated in the production of a technical report (JBA, 2007). 1.2.2 Outputs The RWRS identified and recommended a number of restoration and management measures including: 1. Implement structural modification to lower, remove or by-pass water control structures at mills.

2. Raise bed levels and restore the gravel bed substrate where appropriate.

3. Narrow over-widened sections of river.

4. Introduction / retention of woody debris.

5. Reconnection of 8km of channel to its original channel.

6. Reconnection of the river to its floodplain through removal of embankments where appropriate.

7. Creation of berms to stabilise silt / control silt deposition in the channel.

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The strategy culminates in a suite of high level recommendations presented for the three reaches in Unit 51. This provides a framework for delivering restoration and a starting point for the implementation of restoration on a reach by reach basis. 1.3 Feasibility Assessment aims The overall aim of this feasibility assessment, and hence this report, is to progress the implementation phase of restoration and deliver the measures required for the river to meet its objectives under the Water Framework Directive and to meet the PSA targets for the River Wensum SSSI. The key objectives of this feasibility assessment are to:  Determine the most suitable restoration measure, or suite of measures, for Reach 14, Reach 15 and Reach 16.  To consult with local landowners and stakeholders on the opportunities and constraints for restoration on a reach by reach basis.  To subsequently recommend an overarching restoration and river management conceptual design for Unit 51.  To provide a detailed cost estimate of implementing the conceptual design.  Undertake an environmental scoping assessment of the recommended restoration options. In restoring the hydrological linkage between the river and its floodplain, there should also be consideration of the hydrological linkage between the river SSSI unit, and adjacent terrestrial SSSI units. There are four terrestrial SSSI units adjacent to Unit 51 of the River Wensum SSSI (see Appendix D). This feasibility assessment builds on the RWRS by considering the measures recommended in the strategy, as well as new options for river restoration and river management. A process of Multi-Criteria Analysis (MCA) has been used to determine the most suitable restoration measures or suite of measures for each reach. Section 1.4 provides further detail regarding the adopted methodology. 1.4 Methodology This feasibility assessment involved undertaking the following key activities listed in chronological order. These are described in detail in Sections 1.4.1 to 1.4.7, and Figure 1.3 illustrates the process. 1.4.1 The establishment of detailed baseline conditions for a specific reach. A large amount of baseline data exists for the River Wensum. Numerous reports and raw data were reviewed as part of this feasibility assessment. The majority of this information relates to the River Wensum as a whole, and detailed reach-specific data is less readily available. Section 3.1 sets out more information. In addition, a number of site visits were undertaken throughout the unit by different members of the project team to confirm the desk-top research. Specific baseline conditions for each reach were mapped on an environmental constraints plan.

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Unit 51: North Elmham Mill to Elsing Mill Reach 14 Reach 15 Reach 16 Elsing Reach Swanton Morley Reach Elmham Reach Establish baseline for each of the reaches individually

MULTI CRITERIA ANALYSIS

Construction of MCA tool: identification of options, and defining the criteria by which they will be evaluated.

Application of MCA tool (Ecology, Project Delivery and Technical aspects considered) for each reach

RIVER RESTORATION OUTLINE SCOPING

MCA identification of preferred (highest scoring) options for each reach

Recommended option and measures for each reach

Recommended options and measures for each of the reaches are considered relative to one another and a cost estimate calculated per measure for the unit as a whole. The cost estimate is further refined by considering how cost savings could be made by using alternative construction materials and phasing the works to reduce double handling

ENVIRONMENTAL SCOPING

Environmental scoping of recommended option for this unit

Consents and permissions identified for the scheme to progress to detailed design and construction

Identification of project risks in progressing conceptual design to detailed design

Conclusion and recommendations

Figure 1.3 - The approach adopted during feasibility assessment for determining the recommended restoration option on individual reaches and the overall river unit

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1.4.2 The identification of a full suite of possible restoration measures, including those recommended in the RWRS A generic list of all management and restoration options possibly applicable to the River Wensum was generated through reviewing key documents such as the RWRS (JBA, 2007) and geomorphological appraisal (Sear et al., 2006), and through public consultation at the drop-in sessions undertaken by the Environment Agency, Natural England and Atkins in late 2008 and early 2009 on units 46, 48, 50, 52 and 53 and late 2009 for units 47, 49, 51 and 54. From the above activities, six main option groups were identified and taken forward for consideration using the Multi-Criteria Analysis (MCA) tool. These options are discussed further in Chapter 5, with further detail given in Appendix A. 1.4.3 The evaluation of restoration, maintenance and alternative options by means of Multi-Criteria Analysis Once identified, the six main option groups were evaluated for each reach using a MCA tool. This was considered necessary to ensure that a transparent, defendable and replicable technique of selecting options could be consistently applied. The MCA technique scores the listed options (and the different measures within the river restoration and alternative options) in terms of the degree to which they meet certain criteria, which are broadly grouped under the headings of ‘Ecological’, ‘Project Delivery’ and ‘Technical’. The highest scoring options / measures were considered to be the ‘preferred suite of options’ for that specific reach and were taken forward for consideration in terms of cost. The MCA technique was carried out on a reach by reach basis. 1.4.4 The development of a conceptual design based on the recommended options and suite of measures for each of the reaches considered The recommended options / measures for each reach were considered and professional judgement was applied to determine the appropriate combination of the reach-specific solutions to realise improved conditions for the SSSI unit as a whole. A conceptual design was developed for each reach and these are displayed on base maps in Chapter 6. 1.4.5 The consideration of costs associated with these options and specific river restoration measures A detailed cost estimate was calculated and this was based on a cost per unit length for the different measures and applied to a conceptual design for each reach. Cost savings from phasing work appropriately and using local materials were explored. Chapter 7 describes this in further detail. 1.4.6 Environmental scoping of the recommended option for the unit The recommended option (conceptual design) was subjected to an environmental scoping exercise, so as to determine the significant environmental issues which would warrant a detailed assessment at the next stage of the process. This includes an Environmental Report to be drafted in parallel with the detailed design. The details of this scoping exercise are provided in Chapter 8. 1.4.7 Identification of potential project risks, permissions and consents As part of the next phase of implementation, consents and permissions that will be required to progress the recommended conceptual design to detailed design and construction were identified along with potential risks to the project. These are described in Chapters 9 and 10, respectively.

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2. North Elmham Mill to Elsing Mill Overview 2.1 Terminology and site location

2.1.1 Terminology To determine restoration options applicable to the River Wensum, the following terms are used: The term ‘unit’ is used only in reference to particular riverine SSSI units, which are officially demarcated sub-components of the River Wensum SSSI. These units, of which there are 9 within the study area (Units 46-54), are up to 20 kilometres in length. Each feasibility report looks at one SSSI unit, and this report addresses Unit 51 (River Wensum, North Elmham Mill to Elsing Mill). The term river ‘reach’ is used to describe smaller stretches of the river that have been defined according to their geomorphological environment. Whilst not related to the SSSI designation, a number of these reaches fall within each unit. This report recommends restoration options that may be appropriate to river reaches 14 to 16. Due to their shorter length, reaches are considered preferable to units for planning restoration. The advantage of taking this approach is that many of the restoration options that apply to the entire unit can be broken down and assessed at an individual reach scale. The term ‘section’ has been used as a generic term referring to any portion of the river. For example, ‘the section of river between the bridge and the mill’. The term ‘option’ is used to describe a suite of measures that could be implemented to return Unit 51 to ‘unfavourable recovering’ or ‘favourable’ ecological condition and address WFD hydro- morphological quality issues. For example ‘Do nothing’, ‘Do minimum’, ‘River restoration’ and ‘Targeted maintenance’ are all options. The term ‘measure’ is used to describe a specific technique or work element that falls within an option. For example, bed raising is a measure of the ‘River restoration’ option and silt removal at mill ponds is a measure of the ‘Targeted maintenance’ option. 2.1.2 Site location This feasibility report addresses options for SSSI Unit 51, and its three component reaches, Reach 14, Reach 15 and Reach 16. These are listed below in downstream to upstream order and shown in Figure 2.1.  Reach 14 – Elsing Reach  Reach 15 – Swanton Morley Reach  Reach 16 – Elmham Reach. This SSSI unit is located within the administrative boundary of Breckland District Council. The area is lightly populated and there are a small number of residential and agricultural buildings along the river valley.

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Figure 2.1 - Location of Reaches 14 to 16 within Unit 51

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2.2 Previous works within Unit 51 Since its designation as a SSSI in 1993 there have been a variety of engineering and environmental surveys and investigations carried out on the River Wensum. A number of river restoration schemes have already been implemented in Unit 51. These works are summarised in Table 2.1. Flood risk maintenance works have also been conducted in this unit, and these are detailed in the relevant baseline tables in Section 3. Table 2.1 - Summary of previous restoration works consented on Unit 51

Reach Location Previous Works Consented Year

14 Elsing Reach None identified. n/a

Phase I: Installation of 3 riffles, 3 fish fry bays, berm 2005 construction.

Phase II: Installation of 2 riffles, a gravel bar, two berms and bank reprofiling works downstream of 2005 Bailey Bridge. 15 Swanton Morley Reach Phase III: Installation of 3 off-channel fry refuges combined with bank grading and wet shelf / berm 2006 creation adjacent to fishing lakes.

Phase IV: Installation of 2 glides and bank 2008/2010 reprofiling, plus fishing platforms and board walk

16 Elmham Reach Billingford meander loop reconnection. 2001

The River Restoration Centre has undertaken a series of project appraisals for restoration works completed in this unit including the phased works at Swanton Morley and the Billingford meander loop reconnection (Mant and Fellick, 2007). Works at Swanton Morley are described as being specifically aimed at improving fisheries in the reach and the appraisal of the first three phases of work undertaken identified varying levels of success. In summary, fry refuges and riffles created in Phase I and II works were shown to have been largely successful, although monitoring of performance over time was recommended to address concerns relating to the potential for siltation to compromise habitat function. Negative elements of the scheme included the berms created during Phase II, which are described as being of insufficient size to promote the flow variation required to improve in-stream habitat conditions. The need for further restoration was identified to address the degraded geomorphological condition of the reach. The Billingford reconnection appraisal identified that the original loop dimensions were sufficient to take all the flow from the River Wensum and that there was a need for sensitive management of the loop to ensure the protection of the habitats it contained. Subsequent site visits undertaken by Atkins (in January 2011) showed that only partial flow passes through the meander loop and that larger scale restoration works to reinstate full flow through the loop may be required to ensure effective functioning and reduce the need for maintenance. 2.3 RWRS restoration vision for Unit 51 A condition assessment of the SSSI was conducted by Natural England in 2010. All riverine SSSI units were recorded as being in ‘unfavourable no change’ condition. The vision of the RWRS is to provide a framework that leads to the delivery of restoration that improves the condition of SSSI units from their current ‘unfavourable no change’ condition towards a more naturally functioning and ecologically sustainable system in ‘unfavourable recovering’ or ‘favourable’ ecological condition. The RWRS recommended a variety of restoration options for each reach. These are listed in Table 2.2.

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Table 2.2 - Recommended restoration measures for each reach as provided in the RWRS (JBA, 2007)

Reach Length Restoration Recommendation from the RWRS (m)

In the 100m to 200m downstream of Swanton Morley Mill structure and in the immediate scour pool area of good habitat value, no works are required and this area should be conserved and allowed to re-vegetate naturally. Initial work required is for bed and bank stabilisation associated with lowering of Elsing Mill structures at downstream end of reach. Appropriate measures required to manage silt deposits upstream of the mill. Augment bed on average by 1.2m using local gravels wherever possible and create 14 4,830 up to 66 gravel glides or riffles in the reach. The channel is on average 10.1m over- wide and physical narrowing (with associated landscaping and fencing) may have to be considered to restore the full function of the channel in this reach following works at the mill. Adopt / maintain maintenance regime and riparian management to allow channel to create natural variations in local channel width and habitat niches. Post-project monitoring is required, especially in association with works at the mill structure.

Initial work required is for bed and bank stabilisation associated with lowering of Swanton Morley Mill structures at the downstream end of the reach. Appropriate measures required to manage silt deposits upstream of the mill. 15 2,520 Reduce depth by an average of 0.4m and raise the bed by using up to 34 gravel glides or riffles in this reach. Assume reach will narrow naturally in time. Adopt / maintain maintenance regime and riparian management to allow channel to narrow naturally. Post-project monitoring is required, especially in association with works at the mill structure.

In the 100m to 200m downstream of North Elmham Mill and in the immediate scour pool area of good habitat value, no works are required and this area should be conserved and allowed to re-vegetate naturally. 16 1,170 Augment bed on average by 0.5m using local gravels wherever possible and create up to 20 glides or riffles in the reach. Assume reach will narrow naturally in time. Adopt / maintain maintenance regime and riparian management to allow channel to narrow naturally.

These measures are relatively broad-scale and more detailed appraisal will be required to determine the suitability and extent of each restoration measure. To appraise and define these measures, a detailed understanding of reach-specific baseline conditions is required. Chapter 3 of this report presents this baseline.

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3. Environmental Baseline 3.1 Introduction This chapter presents environmental baseline information for Reach 14, Reach 15 and Reach 16. An environmental constraints map for Unit 51 is illustrated in Figure 3.1. A review of the existing environmental setting has been undertaken through a combination of desk study and preliminary site surveys. Data has been obtained from existing survey reports, and discussion with a number of individuals and organisations including Environment Agency internal functional specialists (e.g. Fisheries, Recreation and Biodiversity, National Environmental Assessment Service and Operations Delivery), Natural England, and Norfolk County Council (NCC). Information sources consulted include, but are not restricted to, the following:  The Environment Agency, www.environment-agency.gov.uk  Breckland District Council  Norfolk County Council, www.norfolk.gov.uk  Norfolk Rivers Internal Drainage Board (NRIDB)  Defra Multi-Agency Geographic Information for the Countryside, www.magic.gov.uk  Natural England, www.naturalengland.org.uk  Norfolk Mills, www.norfolkmills.co.uk  Heritage Gateway, www.heritagegateway.org.uk  Norfolk County Council historic maps, www.historic-maps.norfolk.gov.uk  River Wensum Restoration Strategy (RWRS), JBA (2007)  Water Management Alliance, http://www.wlma.org.uk/  River Restoration Centre (Mant, J. & Fellick, A., 2007)  River Wensum Water Level Management Plan (Environment Agency, 2007a)  Environment Agency National Fisheries Monitoring Programme database  Upper River Wensum Strategy Study (Environment Agency/Babtie, Brown & Root, 2003)  Water Vole Monitoring Report – River Wensum and Tributaries (River Wensum Mink Control Project) (Wild Frontier Ecology Ltd, 2007)  River Corridor Surveys for the River Wensum (1995)  River Habitat Surveys for the River Wensum (2006)  Environment Agency Web-Based Flood Mapping (Environment Agency 2010a, accessed February 2011)  Macrophyte Surveys of the River Wensum SAC (Grieve, Clarke & Caswell, 2002)  Crayfish Distribution in the River Wensum – Results & Observations from the 2003 Ecological Appraisal Fisheries Sampling Programme (Environment Agency, 2004)  Information from Norfolk Biological Records Centre. 3.1.1 Approach to presenting baseline information Presenting specific baseline information for each reach allows a better understanding of the existing environmental constraints that need to be considered when developing river restoration options. Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 16

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This information will be included in the options appraisal process and the Multi-Criteria Analysis (MCA). More information about the aims and objectives of the MCA is provided in Chapter 5. Baseline information common to environmental features across all reaches is described in Section 3.2 and Table 3.4, and specific baseline information specific to each reach is described in Tables 3.5 to 3.7. Figures 3.1 to 3.4 and supporting plates complement the baseline text. 3.1.2 Applicable environmental legislation and policy Environmental legislation that drives this project will need to be considered alongside associated restoration and management options. Legislation include:  The Conservation (Natural Habitats &c.) Regulations 1994 (as amended).  The Wildlife and Countryside Act 1981 (as amended).  The Conservation of Habitats and Species Regulations 2010.  The Eels (England and Wales) Regulations 2009. 3.1.3 Limitations to collating baseline information The baseline data has been derived from a review of existing information and preliminary walkover surveys. There are a number of gaps in the baseline data which will need to be addressed during the ongoing Environmental Impact Assessment (EIA) should restoration options identified in this report progress to the detailed design stage. 3.2 Common environment features across all reaches

3.2.1 Defining the character of chalk rivers A prominent feature of the cretaceous deposits of England is successive strata of chalk which dip gently to the west and are exposed along a wide front running roughly diagonally from Hampshire to Norfolk and Lincolnshire. In Norfolk, chalk strata predominate as the underlying geology. However, as one travels north from Hampshire to Norfolk, the influence of the chalk on the land surface becomes increasingly masked by glacial and fluvio-glacial silts, sands, gravels and boulder clays. This reflects the fact that, even during the most severe glaciations over the Pleistocene period, the ice-sheets only extended as far south as the Thames and south of this, the landscape and river features are in closer contact with the underlying chalk layers. All chalk rivers are characterised by a high base flow throughout the year, with buffering of high flows during the winter as water percolates into the underlying aquifer, and buffering of low flows during the summer as water is gradually released from the aquifer. However, the influence of superficial deposits has a profound impact on how the chalk river habitat is expressed on the land. The southern chalk rivers such as the Hampshire Avon, the Frome, and the Test are regarded as ‘classic’ chalk rivers. In some of these, up to 90% of the flow enters the river through its bed, and as a consequence there is a low density of tributaries in the catchment. As these rivers lie very close to the chalk, there tends to be a relatively smooth pattern of flow accretion along the length of the river. Accretion tends to be greatest along those reaches with the highest gradient, and decreases as the river reaches the lower gradients typical of mature river and floodplain. The close association of the river bed to the chalk bedrock means that the headwaters are often winterbournes (watercourses which only flow in winter due to a seasonal increase in the water table). The way in which the chalk river is expressed is affected where the chalk is obscured and overlain by a considerable depth of superficial clays, sands and gravels. In most cases, it means that the chalk aquifer is separated from the river by one or more intermediate aquifers within the superficial deposits. Where the properties of the overlying drift change across the catchment, this results in a situation where tributaries from some sub-catchments more closely resemble chalk rivers than

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others. In situations where the land surface is less permeable, then there will tend to be a higher density of tributaries. Deep deposits of superficial material between the chalk and the land surface prevent the occurrence of winterbournes. Since northern chalk rivers run over material of varying permeability, so the level of accretion is more variable along different reaches. In Norfolk, the hydrology of chalk rivers is further complicated by the fact that the glacially scoured valleys in the chalk run north to south, whereas the rivers tend to run west to east. With northern chalk rivers the nature of the superficial deposits will also influence the proportion of water that reaches the river as overland flow, and also the material that is available to wash into the river and tributaries from rainfall. It will also affect the land use and hence the vulnerability to erosion of soils in the catchment. In Norfolk, intensive arable agriculture is more prevalent than in the south of England, and hence the river faces much greater vulnerability to diffuse water pollution from agricultural sources. Because Norfolk chalk rivers differ from their ‘classic’ counterparts in the south of England, restoration designs that are developed in the south of England may not necessarily be appropriate in Norfolk. The template for a Norfolk chalk river is explored in detail in the Geomorphological Appraisal of the River Wensum by Sear et al. (2006) and also summarised in the River Wensum Restoration Strategy (JBA, 2007). 3.2.2 The chalk river status of the River Wensum As a northern chalk river, the Wensum catchment is characterised by superficial deposits of sands, gravels and clays, resulting in a chalk river habitat which shows some affinities with other lowland river types. These deposits are variable in nature and there tends to be greater permeability towards the north of the catchment, with other areas characterised by more impermeable clays. However, as with other chalk rivers, there is a very high base flow and there is no ambiguity that this is a chalk river, with accretion from the aquifer throughout its length. The variability in overlying substrates, and complex underlying geology and landforms, results in the River Wensum exhibiting a higher density of tributaries than is characteristic of ‘classic’ chalk rivers. It also influences the availability of material that can be washed into the system during rainfall events, and some of the sub-catchments tend to accrete large volumes of sand. The system has been significantly impacted by the influence of intensive arable agriculture, which dominates much of the Norfolk landscape, and has lead to much higher vulnerability of soils to erosion than would have been the case post war, when Norfolk was characterised by a more mixed agricultural system. Whilst the Wensum retains its baseflow connectivity throughout its length, even to Costessey, the increasing thickness of the overlying glacial drift, sands and gravels along the lower catchment (downstream of Fakenham) increasingly dominates the physical character and structure of the river. As a result, the lower Wensum does not exhibit the characteristics of the classic southern England chalk rivers, where the underlying chalk is consistently closer to the river bed and influences the character of the river to a much greater degree. Another feature of the Wensum is that the river course reflects the periglacial conditions that prevailed immediately after the retreat of the last ice age. At this time, the river was a high energy system with a wide meandering form that cut down into superficial deposits, creating a wide valley and floodplain within the landscape. The low energy system of later periods has modified this large-scale meandering system with secondary sinuosity within the floodplain. This pattern is well represented on the lower reaches of the river between Ringland and Hellesdon. As previously described, the impact of intermediate aquifers in the overlying deposits means that winterbournes are not expressed within the landscape in the way that they are in the ‘classic’ chalk rivers. Despite the majority of the Wensum floodplain remaining relatively natural and managed for grazing, the drainage of the catchment has been substantially altered over time by channel

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simplification, floodplain drainage and the presence of mills and their associated structures. The mill structures exert a disproportionate impact on the river, so that in many cases the Wensum behaves more like a series of linear lakes than a free-flowing river. A further complexity of impounded reaches is that it is no longer possible to drain the land directly into the river, and a secondary drainage system has been developed on the floodplain on either side of the river, draining back into the river immediately below the mill structures. This pattern is repeated at most of the 14 mill structures along the river, the arterial drains being managed by the Norfolk Rivers Internal Drainage Board. On free-flowing reaches, dredging activities have also had profound impacts on the river, resulting in channel deepening and removal of the gravel bed. The Geomorphological Appraisal demonstrated that the Wensum was such a low gradient system that it was unable to replace these gravels through natural processes, and the only mechanism through which the river is able to reduce the cross-sectional area of the channel is through the development of silt berms which result in a further narrowing and deepening of the system. Despite these changes, in 1980 Holmes classified sections of the upper river as Joint Nature Conservation Committee (JNCC) River Type III (chalk rivers and other base rich rivers with stable flows), with downstream transitions to Type I (lowland rivers with minimal gradients on mixed geology in England). In 2002, CAPM reclassified the upper reaches as Type IIIb to Iva (base rich / neutral impoverished rivers, normally close to source) and the lower reaches were similar to the middle reaches Type Ic to IIc, both of which demonstrated a degraded river type compared to previous surveys. As indicated in the previous section, it is essential to have a clear understanding of the characteristics of a Norfolk chalk river before developing detailed restoration designs. The studies carried out as part of the Geomorphological Appraisal, River Wensum Restoration Strategy and these feasibility assessments have enabled us to refine our knowledge and understanding of the expected form and function of the Wensum. 3.2.3 Historic environment The historic environment along Unit 51 is particularly rich, not least because of a former Roman town located at Billingford (approximately 1km east of the upstream end of the unit) which has resulted in significant spot finds and architectural remains of buildings, roads, bridges and other associated structures. The record of the area also dates back to prehistoric and Neolithic eras with evidence of flint-worked tools. There are also records of Bronze Age finds of metal and other objects and evidence of Saxon settlements. Records for later periods include evidence of cropmarks, land boundaries and many other medieval features and a 15th century castle and various moated dwellings. The area was also a key location during both World Wars, particularly at Hall, built in 1850 by Charles Barry (son of the Architect of the Houses of Parliament). This has since been restored from a ruined state in the 1950s and is now a listed building along with many of its associated buildings and features. It was a station for a cavalry unit in WWI and also played a strategic role for the RAF in WWII. Other features in the area include concrete tank blocks near North Elmham Mill and a plane crash site in Reach 14. A site at Swanton Morley was developed as an RAF airfield in 1940, and since 1996 has been used by the Army for the Robertson Barracks. Archaeological investigations have been extensive across the area and have yielded a wealth of information documenting a long history of human activity. In addition there are many period and listed buildings with particular historical significance, ranging from former working mills and farm buildings to castles and halls. The likelihood of encountering archaeological items as part of the restoration works is therefore relatively high and consideration of the potential for historical river crossings will also be required.

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3.2.4 Landscape character and visual amenity The character of the Wensum and Blackwater (Wendling Beck) is described in the Breckland Landscape Character Assessment (2007). The Wensum valley is carved into the Upper Chalk and overlying chalky boulder clay. Drift deposits of sand and gravel deposited by glacial meltwaters form characteristic features of the valley sides, and strongly influence soils within the valley. Sand and gravels have been exploited through mineral working, resulting in a number of flooded pits along the valley floor. The Wensum is joined by its main tributary, the Black Water, near Billingford Hall. The river forms a broad, shallow valley, with the topography varying between 20m and 40m AOD. Land within the river corridor is still traditionally managed pasture, creating a series of important seasonally flooded grasslands and a mosaic of meadow and marsh habitats. Pastoral fields are medium sized, irregular and defined by rural style fencing, ditches and occasional hedgerows, often complementing the meandering patterns of the Wensum. The higher ground of the valley sides is characterised by medium sized, geometric fields bounded by hedgerows and is generally under arable cultivation. The area supports important habitats including osier and alder plantations, pollarded willows and a small number of ancient woodlands (e.g. Sennowe Park and near Worthing Mill), with tree species including ash, oak, hazel and birch. The character area falls into the core areas category of the Ecological Network Mapping Project for Norfolk, due to riparian habitats and biodiversity, and it is highlighted as an area for creation of reedbeds (Norfolk BAP Priority Habitat) and coastal/floodplain grazing marsh. A strong character is created by the meandering river course, associated wetland habitats, small scale pastures and networks of ditches, with traditional red- brick and weatherboard mills, creating an intimate but varied landscape. The landscape strategy of the Landscape Character Assessment has an overall aim to conserve the tranquil, pastoral, undeveloped character of the River Wensum and Blackwater and manage, or where appropriate increase, natural floodplain habitats such as grassland, reedbeds, watermeadows and grazing marsh. Wooded lanes, hedgerows and hedgerow trees also create a sense of enclosure and historic character and should be maintained. The natural meandering course of the Wensum and associated floodplain habitats are noted as being especially sensitive to river engineering and to changes in water quality and water flows.

3.2.5 Land use The land associated with this unit is particularly rural in nature and built development is largely restricted to three small villages that are set away from the main river, namely Swanton Morley, Billingford and Elsing. An RAF airfield was developed at Swanton Morley during World War 2. The site is now used by the British Army as Robertson Barracks. There are few dwellings along the river corridor, other than farms and a former 15th century castle site. The upper reaches of this unit (Reaches 16 and 15) are flanked by former sand and gravel extraction works which now form flooded lakes. There is no history of gravel extraction within Reach 14. The immediate river corridor supports relatively few trees (particularly Reach 14), except for pockets of woodland, poplar plantations or riverside trees that are present as individuals or groups of trees along the bank. Aside from the former gravel pits, the majority of the floodplain is managed as semi-improved grassland, with wetter areas forming marshy grassland, all of which are used for grazing by cattle. Poaching of the river margins by cattle occurs in places. The floodplain is drained by a network of IDB and farmland drains, particularly along Reach 14, where previously it is likely that the area formed a wide marshy wetland habitat. Historical dredging works have resulted in the formation of spoil embankments along both banks of the river. Where ground is drier and/or further away from the river’s influence, the land is used for intensive arable crops and there are also a few larger areas of woodland. Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 20

River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

3.2.6 River management The Environment Agency is the operating authority for the River Wensum within the SSSI, as well as the Blackwater, whilst the Norfolk Rivers IDB is the operating authority for the other major watercourses (Main Drains) within the Water Level Management Plan (WLMP) area (Environment Agency, 2007a). The Environment Agency have permissive powers to undertake maintenance work on the river to reduce flood risk to people and property. This includes weed cutting by boat along sections of this unit, and light trimming of tree boughs to facilitate passage of the weedboat. Little work has been undertaken in recent years, especially since the restoration works were completed above Swanton Morley. Ad hoc works including berm trimming (Reach 14) and breach repair (Reach 15) have also been undertaken in this unit. IDB main drains are maintained according to their operational maintenance guidelines (NRIDB, 2007). 3.2.7 Water mills Water milling has historically taken place at 14 locations along the River Wensum. At six of these the mill buildings remain in use (residential), with most (but not all) of the mills being Grade II listed structures. In times of flood, mill owners may independently open their structures (if operable) as they see fit, with no consistent river-wide approach (Environment Agency, 2007a). By retaining high water levels upstream, the mill structures have a major influence on the river. They have the potential to constrain the scope and effectiveness of river restoration, especially in sections of channel upstream of the mills. Unit 51 features the following mills:  Swanton Morley (site of) (TG 02050 18479)  Elsing Mill (TG 05000 17683). North Elmham Mill is located immediately upstream of Reach 16 and has been considered in the Unit 50 Feasibility Report (Atkins, 2009). Swanton Morley Mill (site of) Key aspects are as follows:  There is no mill building.  Two fixed weirs remain, one at the site of the mill building on the main channel (Plate 1), the second located 250m upstream on the bypass channel (Plate 2). Two bridges are located immediately downstream of the site of Swanton Morley Mill (Plate 3). These are named as Swanton Morley 2 Arch and Swanton Morley 3 Arch bridges. Both are masonry structures, the former stands on the bypass channel and the latter on the main channel. Both bridge sites are accompanied by weirs and operated by the Environment Agency as flow gauging stations. It should be noted that issues relating to both of the gauging structures, although technically located in the uppermost section of Reach 14, are considered alongside options presented for Reach 15 within this report. Any modifications to the structures will affect the upstream sections of watercourse and so it is logical to consider the impacts of any changes as part of restoration options for Reach 15. Both gauging structures are considered to impede fish passage.

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Plate 1 – Site of Swanton Morley Mill showing fixed weir on main channel at site of mill (TG 02050 18479, January 2011)

Plate 2 – Site of Swanton Morley Mill showing weir on bypass channel (TG 02205 18691)

Plate 3 – View of 2 Arch (left) and 3 Arch (right) bridges at Swanton Morley Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 22

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Elsing Mill (Plate 4) Technical details of the mill layout are given in the WLMP (Environment Agency, 2007a). Key aspects are as follows:  There are two channels, the main channel and a bypass channel.  The main channel has a fixed wooden board weir in the mill wheel-race.  On the bypass channel are two vertical lifting gates. Alongside are the remains of a pumping station (which originally supplied water to ), through which a small proportion of flow passes.  Under low-medium flows, the flow is split 30:70 between the bypass channel and the lifting gates in the mill.  At higher flows, the mill structures are opened more, enabling water to pass through the wheel-race. Operation is governed by observation of freeboard in the channel (based on a visual reference point rather than a gauge-board).  Both the mill buildings and water rights are privately owned. The RWRS (JBA, 2007) notes that the main channel and bypass channel are impassable to fish.

Plate 4 – View of Elsing Mill (TG 05000 17683) showing vertical lifting gates on bypass channel in foreground A draft Mill Operating Protocol (MOP) for the River Wensum has been developed by Atkins (Atkins, 2010), following consultation with owners and operators, to provide a unified approach to mill gate operation in support of the restoration strategy. The MOP is a first look the lowering of retained water levels, where this can be achieved through operational modifications only. In relation to Unit 51, modelling has been undertaken to quantify the effect of operating the flow control structures (steel vertical lifting and wooden gates) at Elsing Mill on water levels upstream. This exercise identified that, by using changes in operational procedure alone, the backwater effect created at Elsing Mill cannot be significantly altered. Summary information relating to the mill structures in Unit 51, as provided in the WLMP, are presented as Table 3.1.

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Table 3.1 - Mill details in Unit 51 (Environment Agency, 2007a)

Mill Name Section Drop at Backwater Backwater Structure Length Structure Length (mean Length Elevation (m (km)* (mean flow), (km) (% of section AOD) flow), length affected (m) by backwater from mill)

Swanton Morley Mill 3.66 0.64 3.17 87 18.52

Elsing Mill 5.48 1.85 4.71 94 17.5 * Distance to next mill upstream

3.2.8 Soils and geology The predominant solid geology of the area is Chalk, a fine grained fissured limestone. The Chalk unit comprises Upper and Middle Chalk overlying Lower Chalk. The Chalk is underlain by the Gault clay, which consists of impervious grey clays. This in turn is followed by undifferentiated Carstone and Sandringham Sands. The Carstone comprises brown, ferruginous, well-jointed medium to coarse grained sandstones. The Sandringham Sands comprise brown, ferruginous fine grained sands which pass down to grey-green glauconitic sands and sandy clays. The predominant soil type occurring adjacent to the River Wensum throughout Unit 51 is a seasonally wet deep sand and peaty soil (Isleham 2). Outside of the immediate valley floor, a deep coarse fine loamy soil with slowly permeable sub-soils (Burlingham 2) dominates (additional references in Sear et al., 2006; JBA, 2007). In terms of ground contamination, chemical analysis of in-river silts was undertaken by JBA in 2008 (through the Environment Agency National Laboratory Service) at different points along the River Wensum. Data was generally collected upstream of mills, including Elsing Mill in Reach 14. Analysis showed non compliance with the soil guidance value for arsenic at this site. 3.2.9 Water environment Quality assessment Since the adoption of the European Water Framework Directive (WFD), water quality is reported through a continuous process of planning and delivery as identified in the Anglian River Basin Management Plan (RBMP) (Environment Agency, 2009d). The WFD has introduced a formal series of 6 year cycles; the first ending in 2015. After further planning and consultation the plan will be updated and reissued. The WFD sets an objective of aiming to achieve at least ‘good status’ or ‘good potential’ in all water bodies by 2015 or, provided that certain conditions are satisfied, seek to achieve the objective by 2021 or 2027. The Anglian RBMP identifies the River Wensum upstream of Norwich as a heavily modified water body. By definition, surface waters classified as heavily modified are not able to achieve natural conditions, and therefore it is not possible for such water bodies to reach ‘good ecological status’. Quality in heavily modified water bodies is measured in terms of ecological potential. This is a measure of biological, chemical and hydromorphological conditions. The current overall ecological quality of the water body relevant to Unit 51 has been assessed as bad ecological potential. This is attributed to the water body not supporting good quantity and dynamics of flow as well as biological failures, namely ‘bad’ diatom communities (Table 3.2). The

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water body has objectives to reach good ecological potential by 20271 and good chemical status by 2015. Table 3.2 - WFD quality assessment (Environment Agency, 2010b)

Waterbody Name Current Ecological Physico-chemical Hydro Quality Supporting Element Morphological Quality Supporting Element Quality Wensum US Norwich Overall - bad potential* Overall - Good quality Overall – not high

(GB 105034055881) Diatoms (bad) Ammonia (high) Hydrology (moderate) Fish (moderate) Dissolved oxygen (high) Macroinvertebrates(high) pH (high) Phosphate (good)

Abstractions and discharges The Environment Agency (see Entec, 2010) has undertaken a Review of Consents (RoC) in the Wensum catchment (Regulation 50 of the Conservation (Habitats &c.) Regulations, 1994). The report predicts impacts of licenced abstractions on the hydrological regime of the River Wensum SSSI to identify whether these impacts are acceptable or unacceptable in terms of their effects on the ecology of the site. A Site Option Plan will identify any changes which the Environment Agency believes are necessary to ensure no adverse effect on site integrity and to achieve the RoC Stage 4 Environmental Outcomes, and will make general proposals as to how the changes could be achieved. To feed into this process the Environment Agency and Anglian Water carried out an aquatic macrophyte survey of the river (@OneAlliance, 2007). This study confirmed that all reaches of the River Wensum were capable of supporting ‘Ranunculus vegetation’, but that a number of components of this biotope were, at present, poorly represented. Review of Environment Agency GIS data (Environment Agency, 2009c) shows there to be one licensed surface water abstraction in Unit 51 in the upper most section of Reach 14. This abstraction is licensed to 0.1 Ml/d (7/34/11/*S/0326) and been identified as having an in- combination effect on the river by the Habitats Directive Review of Consents – Stage 4 (Entec, 2010). Twelve groundwater abstractions occur within 1km of the main river channel in Unit 51, of which eight are identified as agricultural, two as industrial and two as other uses. All of these abstractions are licensed for quantities below 1 Ml/day. The single largest abstractor in the Wensum catchment is Anglian Water Services Ltd., taking groundwater from a number of boreholes, and a surface water abstraction at Costessey, for public water supply. Abstraction of surface water and ground water also occurs for agricultural needs, mainly summer spray irrigation (Environment Agency, 2007a). Seven non sewage treatment works (STW) licensed surface water and three licensed STW discharges occur within 1km of the River Wensum in Unit 51. Surface water drainage The Norfolk Rivers IDB drains areas of agricultural land, and residential surface water run-off, by using tributaries along the River Wensum. Local surface water flooding tends to occur in flashy rainfall events. This can be exacerbated in the event that main river flows overtop and water from the river drains into IDB drains which outfall near built-up urban areas. The location of IDB drains is provided in Figures 3.2 to 3.4.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

A wider initiative called the England Catchment Sensitive Farming Delivery Initiative (ECSFDI) was launched in 2005 and is being promoted by Natural England with the aim of raising awareness of diffuse water pollution and encouraging voluntary action from farmers to minimise the risks of diffuse pollution. The 50 priority catchments, including the Wensum, were identified jointly by the Environment Agency and English Nature, and cover about 40% of the agricultural area of England (with about 50,000 farmers, of which some 30,000 manage holdings of over 20 hectares in size). Catchments were identified using data gathered for Water Framework Directive (WFD) purposes on nitrate, phosphate and sediment pollution, combined with data on sensitive freshwater fisheries, chalk streams, failing bathing waters, groundwaters and SAC-designated lakes. The ECSFDI has contributed to the achievement of the Government’s PSA target for the end of 2010 for 95% of SSSIs to be in ‘favourable’ or ‘unfavourable recovering’ condition. A specific sediment fingerprinting exercise, to distinguish different sources of sediment, is being undertaken on the River Wensum which is expected to be published in 2011. This may contain further baseline information which will input to the RWRS, in particular the strategy’s ecological improvement objectives. In much of the River Wensum, it is considered that diffuse pollution from agriculture comes from tributaries whereas the immediate floodplain does not pose such a threat. 3.2.10 Utilities At the time of submitting this report, comprehensive information regarding utilities had not been obtained for Unit 51. More information would be collated should this unit progress to detailed design, in order to address this residual data gap. 3.2.11 Condition of attributes in Unit 51 For units of river SSSIs to be regarded as in ‘favourable’ condition, targets on various attributes need to be met. Currently, Unit 51 (reaches 14 to 16) is classified as ‘unfavourable no change’. The main reasons for the adverse condition of the SSSI Unit 51, according to the condition survey undertaken by Natural England in March 2010, are inappropriate water levels, inappropriate weirs dams and other structures, invasive freshwater species, siltation, water abstraction, water pollution, agriculture / run-off and water pollution discharge (Table 3.3). Table 3.3 - Condition summary of Unit 51 attributes (Natural England, 2010)

Location European Features Siltation JNCC Type Water Quality Access Channel Structures Biological Disturbance Flow Management

River Wensum from North Elmham Mill to Elsing Mill U U U U U U U F F (Unit ID 1025556)

Key: U = Unfavourable’ F = Favourable

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Figure 3.1 - Environmental constraints on Unit 51

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Table 3.4 - Baseline information common to Unit 51

Environmental Baseline Information Feature

 White-clawed crayfish are found along most of the unit, particularly in the upper reaches. There are some locations where signals and white-clawed crayfish appear to be coexisting. Ecology (Protected  Water voles have been recorded within all three reaches (Wild Frontier Ecology, 2007). Species)  Otter have been recorded at various locations in all three reaches (EA database information).  Fisheries surveys (Reach 15) have found eels, bullhead and brook lamprey (EA database information).

 SAC and SSSI Units: Unit 33: Swanton Morley Parish Council Land. Ecology (Statutory Unit 34: Mill Street East Swanton Morley Farms. Designated Unit 35: Mill Street Swanton Morley Parish Council. Areas) Unit 36: Mill Street South East Swanton Morley Farms. Unit 51: River Wensum.

Ecology (Non-  Broads ESA. Statutory  There are two County Wildlife Sites within the unit, site 668 (Swanton Morley Gravel Pits) and site 669 (Gravel Pits). Designated Areas)

 Fisheries: Fisheries data for this unit shows the population to be dominated by coarse species with dace (Leuciscus leuciscus), chub (Leuciscus cephalus) and minnow (Phoxinus phoxinus) being numerically abundant in the most recent surveys. Surveys have also highlighted the presence of two species of European interest, namely eel (Anguilla anguilla) and brook lamprey (Lampetra planeri), have been recorded in this unit. Bespoke surveys have also identified the value of off-river drain habitats as supporting sites for roach (Rutilus rutilus) populations (Environment Agency, 2007b).  Invertebrates: One EA routine sampling site is located below Swanton Morley weirs. A wide diversity of invertebrates have been found at this location, some of which are of local or national conservation interest (see baseline table for Reach 14). Ecology  Flora: Both the 1995 RCS and Grieve et al. (2002) noted that in-channel vegetation is often dominated by filamentous algae, particularly downstream of (Fisheries, the sewage treatment works in Reach 14. Other aquatic or marginal species of interest include flowering rush and lesser water-parsnip. Unbranched Invertebrates & bur-reed, various pondweeds (horned, fennel, perfoliate and opposite-leaved), spiked water-milfoil, and arrowhead were other commonly recorded Flora) species. Fan-leaved water-crowfoot was recorded in two locations and stream water-crowfoot was recorded in Reach 16 where habitat was suitable (1995 RCS).  Marginal vegetation includes reed sweet-grass, reed canary-grass, water-cress, brooklime, water forget-me-not, pink and blue water-speedwells. Bank vegetation consists of grasses, great willowherb, thistles and other ruderal species.  IDB drains support a number of the species listed above and also horsetails, valerian and sedges, and water starwort where they have been found to hold water (1995 RCS).

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Environmental Baseline Information Feature

Ecology  Swanton Morley is an interface location where both signal crayfish and white-clawed crayfish appear to be coexisting (EA, 2004) (Invasive / Non-  Canadian pondweed was noted in the 1995 RCS as present within reaches 14 and 16. Monkey flower was noted in Reach 15. Native Species)

 Generally, individual or scattered trees are found along the unit, with pockets of woodland and occasional poplar plantations. Willows are frequently found (including white willows, crack willows and osier). Other species recorded included horse chestnuts, ash, alder, oak and hazel. Reach 14 and part Ecology (Trees) of Reach 15 are particularly sparse in terms of riparian tree cover.  Scrubby areas comprise hawthorn, elder, bramble and rose.

 Reach 16 retains pool and riffle features, with mid-channel bars despite being over-widened and embanked. Reaches 15 and 14 are increasingly widened, deepened and generally provide poor chalk river habitat with sand and gravel forming the main bed substrates, with sand dominating in some Geomorphology areas. Recent river restoration work within Reach 15 has resulted in local improvements to the form and function of the river.  Between straightened mill reaches, a generally meandering planform is retained, although there has been some straightening for substantial gravel pit excavations (most now flooded and providing wetland habitats).

Previous  Restoration works have been undertaken in reaches 15 and 16 of this unit. Restoration Works

 The flat valley floor provides an extensive floodplain. Relatively few properties are at risk of flooding though, and EA web-based flood mapping indicates Flood Risk that most buildings lie outside Flood Zones 2 and 3. Pasture and flooded gravel pits are the main land uses within the floodplain.  Mill buildings at Elsing and North Elmham are at risk of flooding.

 There is relatively little public access along this unit. Human  No statutory footpaths are present to provide riverside walking, though there are some permissive paths in Reach 14. Burgh Common and Mill Common Environment at Swanton Morley are CROW access land.  Angling clubs hold fishing rights to some sections of river channel and to some flooded gravel pits.

 The unit (particularly Reach 15) is rich in historic features and has many recorded finds that date from the prehistoric-Neolithic periods, through Bronze and Iron ages, Roman, Saxon and medieval periods. Billingford was a former Roman town and is a particularly important historic area. Historic  Many listed buildings are located in nearby villages. The road bridge at Swanton Morley, which dates back to the 1830s, is also listed. Environment  References: Heritage Gateway and Listed Buildings Online web-based searches within 1km of selected point locations along the main river channel that cover each reach (1 or more points for each reach depending on extent of reach).

 The majority of the floodplain consists of improved or semi-improved grassland. Several flooded gravel pits also lie within the floodplain along this unit, particularly in the lower end of Reach 16 and much of Reach 15. Small pockets of broad-leaved woodland and poplar plantations are present. There are Land Use occasional gardens associated with riverside properties.  Away from the valley bottom the landscape is dominated by arable cultivation.

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Environmental Baseline Information Feature

Traffic and  The only road access points are the B1145 at North Elmham Mill, the B1147 at Swanton Morley and a minor road crossing at Elsing Mill. Transport

Utilities  No detailed information has been compiled for this unit.

River  The Environment Agency undertakes permissive channel maintenance works, where required, to manage flood risk. Maintenance works may include Maintenance weed cutting, breach repairs and berm and tree bough trimming.

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3.3 Environmental baseline for each reach within Unit 51 Specific baseline information for Reaches 14, 15 and 16 is described in Tables 3.5, 3.6 and 3.7, respectively (ordered in an upstream direction) with accompanying Figures 3.2, 3.3 and 3.4. Representative photographs taken during field visits are presented as Plates 1 to 44. Table 3.5 - Baseline information specific to Reach 14 (Elsing Reach)

Environmental Baseline Information Feature

 Positive signs of water voles have been recorded between 2003/5 and 2007 at Castle Farm and Elsing Mill (Wild Frontier Ecology, 2007).  White clawed crayfish were recorded at Elsing in 1996, but more recently records of both white clawed and signal crayfish have occurred at the upper Ecology end of this reach at Swanton Morley weirs (1996 to 2009 according to EA database information). Signal crayfish were observed in the middle of this (Protected reach during an Environment Agency site visit in September 2011. Species)  Otter have been recorded at Elsing Mill between 1996 and 1997 (EA database information).  Bullhead have been recorded at Castle Farm (1997).  Brook lamprey have been recorded u/s of Elsing Mill (1997).

 SAC and SSSI units: Ecology Unit 34: Mill Street East Swanton Morley Farms. (Statutory Unit 35: Mill Street Swanton Morley Parish Council. Designated Areas) Unit 36: Mill Street South East Swanton Morley Farms. Unit 51: River Wensum.

Ecology (Non-  Broads ESA. Statutory Designated Areas)

 Fisheries: No fisheries data is available for this reach.  Invertebrates: An Environment Agency routine macroinvertebrate site is located downstream of the B1147 bridge at Swanton Morley (but upstream of the mill leat confluence) and data from 1995 to 2007 recorded a wide diversity of taxa including flatworms, snails, limpets, pea mussels, leeches, hog lice, shrimps, mayflies, stoneflies, caddis flies, dragonflies and damselflies, beetles, water boatmen and true fly larvae. Biological Monitoring Working Ecology Party (BMWP) scores are usually between 100 and 150 (indicating a good diversity of taxa), but the October 2007 sample scored 90 (with an apparent (Fisheries, absence of caddis fly larvae) (EA database information and Stansfield et al., 2001). Invertebrates & Flora)  Several species of conservation importance have been found including snails (Valvata cristata and Bithinia leachii), mayflies (Baetis buceratus, Ephemera vulgata), stoneflies (Nemoura avicularis, Leuctra nigra, Leuctra fusca), water boatmen (Micronecta poweri) and caddis flies (Agraylea sexmaculata, Athripsodes bilineatus and Ceraclea dissimilis).  Penny Spot Beck has also been sampled (Stansfield et al., 2001) and scored a BMWP of 113 with 20 scoring taxa indicating a diverse community, though no species of particular conservation importance were found.

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Environmental Baseline Information Feature  Flora: The CAPM (Grieve et al., 2002) macrophyte survey assessed ten in-channel sites within this reach and found the dominant species were flowering rush, unbranched bur-reed, yellow-water lily and arrowhead, with filamentous algae (Enteromorpha spp. and Cladophora agg.), reed sweet- grass, perfoliate pondweed, reed canary-grass and duckweed. Filamentous algae were dominant at the lower end of the reach at sites below the sewage treatment works outfall.  The 1995 RCS survey noted channel vegetation consisted of arrowhead, unbranched bur-reed, filamentous algae (Cladophora agg.), occasional water starwort, yellow water lily, perfoliate and fennel pondweeds, common clubrush and spiked water milfoil. Flowering rush was recorded frequently along this reach. Fan-leaved water crowfoot was recorded in the lower end of the reach.  Marginal and emergent vegetation consisted of water-cress, water forget-me-not, pink water-speedwell, reed sweet-grass, reed canary-grass, occasional pond sedge, and fool’s water-cress.  Bankside vegetation consisted of willowherb, reed sweet-grass, water forget-me-not, creeping buttercup, nettle, occasional yellow flag iris, brooklime, blue water-speedwell, hemlock and greater tussock sedge. The floodplain consisted of improved and marshy grassland, occasional gardens, scattered scrub and small pockets of semi-natural woodland. A sewage treatment works is located on the TLHB near the mid-reach point.  Associated IDB drains were noted to support fen bedstraw, water horsetail, reed sweet-grass, reed canary-grass, great willowherb, lesser water parsnip, marsh valerian, yellow flag iris, water mint, common sedge, marsh ragwort, great horsetail and ragged Robin. Some drains supported branched bur-reed, duckweed and water starwort (near the sewage treatment works).

Ecology  Signal crayfish have been recorded at the B1147 and Swanton Morley weirs between 1996 and 2009 (EA database information). (Invasive / Non-  The 1995 RCS noted Canadian pondweed within this reach. Native Species)

 Trees and woodland are very scarce along this reach and occur only as isolated or scattered individuals or small woodland areas. Ecology (Trees)  At Swanton Morley the 1995 RCS noted white willows and occasional hawthorn, elder, alder, gorse, ash, oak, sycamore, maple, horse chestnut and a hawthorn hedge (at Castle Farm). There were occasional patches of bramble and wild rose.

 The habitat downstream of Swanton Morley gauging station has been noted to deteriorate rapidly as the channel has been over widened and simplified, with slow flows and significant sand deposits along the river bed. The backwater effect from Elsing Mill affects most of this reach (EA, 2004). Geomorphology  The 1995 RCS survey noted that the dominant substrates below Swanton Morley consisted of sand and gravel, with some parts of the reach dominated by sand, particularly on the approach to Elsing Mill. Organic deposits were noted downstream of the sewage treatment works.

Previous  None identified in this reach. Restoration Works

 There is a wide floodplain within the valley bottom. This extends up the tributary valley of the Penny Spot Beck. Flood Risk  Elsing Mill and the road crossing at this point are the main built features at risk of flooding.

Human  There are some permissive footpaths on land adjoining the right hand bank of the river. Environment  A few isolated farm complexes are located to the north and south of the river with associated access tracks.

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Environmental Baseline Information Feature  and District Angling Club having fishing rights on the TRHB in this reach from Castle Farm to Penny Spot Beck.

 At the upstream end of the reach the road bridge (dated 1831), associated with the water and former paper mill in Swanton Morley dating back to at least the 1780s, is listed.  There are several listed buildings including Kesmark House (II); Spring Head (Mill Street, II); Church of All Saints (I); the White House (II); houses along Elsing Road (II); the bridge at Swanton Morley (II) associated with Bylaugh Hall (II and II*); Park Farm buildings (II*); the Church of St Mary (I); the Old Farmhouse at Bylaugh (II*); Elsing Mill (II). Historic Environment  Historical Environment and Past Scape Records along this reach are particularly abundant (over 40 records ) and include interesting finds and features from prehistoric to late post medieval periods, many Roman features (including roads, buildings and bridges), a 15th century medieval castle and moat close to a meander of the Wensum, cropmarks, remnants of a post medieval or Roman bridge over the Wensum, boundary features, barrows, military connections during WW2 with Bylaugh Hall and an aircraft crash site.  References: Heritage Gateway web-based searches (including Historical Environment Records and Listed Buildings Online) within 1km of two points along the reach (at TG024176 and TG041175).

 The majority of the floodplain along this reach is improved grassland used for grazing. There is an extensive network of drainage ditches. Land Use  Arable farming occurs across the wider landscape outside the floodplain.  Bylaugh sewage treatment works is located at the mid-reach point.

 The B1147 runs north-south 100m from the TRHB for 1km along the upper reach before crossing the river at Swanton Morley. Traffic and  A minor road runs east-west at distance from the TLHB, passing closest at the northernmost meander at the mid-reach point near Bylaugh Hall. Transport  Access from the southern side of the river is via private tracks associated with Castle, Penny Spot and Wensum Farms. These can be accessed via a minor road between Swanton Morley village and Elsing.

Utilities  No detailed information has been compiled for this reach.

River  In 2004 the Environment Agency undertook trimming works to berms on the TRHB, near Castle Farm, for flood risk management. Maintenance

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Figure 3.2 – Environmental baseline for Reach 14 (Elsing Reach) Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 34

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Table 3.6 - Baseline information specific to Reach 15 (Swanton Morley Reach)

Environmental Baseline Information Feature

 Signs of water voles have been recorded at Swanton Morley Pits between 1997 and 2007 (Wild Frontier Ecology, 2007).  White clawed crayfish have been recorded at Riverside Farm, Waterfall Farm and at the B1147 bridge. Signal crayfish are also present at Swanton Ecology Morley weirs, so both species are interacting at this location (EA database information between 1996 and 2009). (Protected  Otter have frequently been recorded at several locations along this reach (at the Bailey Bridge, Swanton Morley Fisheries, Swanton Morley and Waterfall Species) Farm) between 1996 and 2001 (EA database information).  Bullhead have been recorded at Swanton Morley (1983-97) and at Waterfall Farm (2001).  Brook lamprey have been recorded at Swanton Morley (1994).

 SAC and SSSI units. Ecology (Statutory Unit 33: Swanton Morley Parish Council Land. Designated Unit 51: River Wensum. Areas)

 Broads ESA.  County Wildlife Site 668 – Swanton Morley Gravel Pits. This 10.2ha site is a large eutrophic lake with a small area of acid grassland with young Ecology (Non- woodland. It lies to the west of the River Wensum with the Worthing to Swanton Morley road forming its western boundary and unimproved grassland to Statutory the south. The lake, which dominates the site, holds white water lily (Nymphaea alba), ivy-leaved duckweed (Lemna trisulca), common duckweed Designated (Lemna minor) and Canadian pondweed (Elodea canadensis). The margins have common reed (Phragmites australis), bulrush (Typha latifolia) and Areas) amphibious bistort (Polygonum amphibium). The acid grassland to the south-west has Yorkshire fog (Holcus lanatus), oat-grass (Avenula spp.), Michaelmas daisy (Aster novi-belgii agg.), yarrow (Achillea millefolium) and cow parsley (Anthriscus sylvestris). Patches of woodland are alder (Alnus glutinosa) and oak (Quercus robur) dominated with occasional sallow (Salix cinerea), bramble (Rubus fruticosus agg.) and common centaury (Centaurium erythraea).

 Fisheries: Routine Environment Agency fisheries data is available for one site in this reach, adjacent to the Swanton Morley gravel pit complex (EA site code NOR22). Five surveys have been conducted since 1986, the most recent being in 2006. Fourteen fish species have been recorded in total including both coarse and salmonid species. Of the eleven species recorded in 2006, minnow (Phoxinus phoxinus), dace (Leuciscus leuciscus) and chub (Luciscus cephalus) were the most numerically abundant. Ecology  Two species of European interest, namely eel (Anguilla anguilla) and brook lamprey (Lampetra planeri), have been recorded in this reach. (Fisheries, Invertebrates &  Fish fry surveys were conducted along approximately 1.2km of this reach in 2003. Results identified the relationship between fry presence, flow and Flora) available marginal cover, with fry distribution being limited in homogenous channel sections with little marginal vegetation (Environment Agency, 2003).  Targeted roach (Rutilus rutilus) surveys conducted in April 2006 identified pre-spawning aggregations of roach in the IDB drain which discharges to the mill bypass channel in the lower section of this reach (Environment Agency, 2007b).  During 2010 and 2011 approximately 300 roach, each implanted with a Passive Integrated Transponder (PIT) tag, were introduced to the Wensum at Swanton Morley to enable them to be tracked and monitored. This was a collaborative project between Norfolk Flyfishers Club and the Environment

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Environmental Baseline Information Feature Agency. Monitoring equipment placed at strategic locations along the river is being used to track the movement of the tagged fish (pers. com. Graham Gamble, Environment Agency Fisheries Officer).  Invertebrates: There is no routine Environment Agency invertebrate sampling site within this reach.  Stansfield et al. (2001) collected a sample at Spong Bridge on the Black Water and recorded a BMWP score of 103 and 19 taxa, including the caddis fly Silo nigricornis which is of conservation interest.  Flora: The CAPM (Grieve et al., 2002) macrophyte survey assessed one site in this reach and found unbranched bur-reed, flowering rush, perfoliate pondweed, arrowhead and mole pelt algae (Vaucheria spp.) to be the dominant plant species. Other plants included duckweed, fennel pondweed, creeping bent and lesser water-parsnip.  The 1995 RCS noted that in-channel vegetation consisted of opposite-leaved, perfoliate and fennel pondweeds, flowering rush, filamentous algae (Cladophora agg.), with occasional spiked water-milfoil, horned pondweed, broad-leaved pondweed, unbranched bur-reed and Nuttal’s pondweed. Where the channel was particularly broad and deep, vegetation was generally found to be poor or dominated by filamentous algae. Marginal species included reed canary-grass, water forget-me-not, water-cress, fool’s water-cress, brooklime, blue water-speedwell and reed sweet-grass.  Bank vegetation was frequently cattle grazed and supported creeping thistle, ragwort, dandelion, nettle, hemlock, garlic mustard, false oat-grass, great willowherb and occasional nodding bur-marigold. The floodplain supported improved grassland (cattle grazed), some broad-leaved woodland, flooded gravel pits (supporting fennel, horned and small pondweeds, fringed water lily and reedmace), amenity grassland and small areas of arable cultivation.  IDB drains were noted to support nettle, great willowherb and reed sweet-grass.

Ecology  Signal crayfish have been recorded at Swanton Morley weirs and Waterside Farm (at the downstream end of the reach) between 1996 and 2009 (EA (Invasive / Non- database information) and the area is noted as the key interface location where the two crayfish species appear to co-exist (EA, 2004). Native Species)  Monkey flower and Canadian pondweed were recorded in part of this reach (1995 RCS).

Ecology (Trees)  The 1995 RCS noted occasional broad-leaved woodland, elder, oak, willows (white, crack and osier), ash and occasional poplar plantations.

 This reach is noted to be particularly broad and slow-flowing with embankments along much of its length. Bed substrates, when visible, were noted to Geomorphology consist of sand and gravel (1995 RCS). Several phases of river restoration since 2005 have partially addressed these issues.

Previous  Four phases of restoration works have been completed in this reach between 2005 and 2010 including the installation of riffles, berms and fish fry Restoration refuges (see Table 2.1). Works

 Flood Zone 3 is extensive, particularly along the downstream half of the reach (EA web-based flood mapping). Flood Risk  Generally, housing and residential buildings are located outside Flood Zones 2 and 3.

 There are very few dwellings along this reach, other than a farm in the upper reach and the mill buildings at the downstream end of the reach.  There are no formal or public footpaths along this reach, though Burgh Common and Mill Common on the right hand bank are CROW access land. Human Environment  Swanton Morley Road and Worthing Road run close to the south of the river.  Both the Norfolk Flyfishers Club and Dereham and District Angling Club operate fisheries in this reach. Public fishing is also available at Burgh Common and a small length of river in the downstream section of this reach.

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Environmental Baseline Information Feature

 Within 1km of the centre-point of this reach there are 4 listed buildings: Billingford Hall and its ice house; Billingford Lodge and the road bridge (dated 1831), associated with the water and former paper mill in Swanton Morley dating back to at least the 1780s. Historic  There are over 50 Historical Environment and Past Scape records, many associated with the area’s rich Billingford Roman town history. However, they Environment also cover prehistoric to post-medieval finds and features identified through years of archaeological investigation, spot finds, and WW2 features.  References: Heritage Gateway and Listed Buildings Online web-based searches within 1km of central reach point (TG016194).

 The floodplain along this reach has been extensively exploited for alluvial sand and gravel extraction. Flooded pits lie to the north of the river in the upper sections of the reach and along both sides of the river in the lower sections.  Areas that have not been quarried along the river corridor form improved /semi-improved grassland with associated drainage systems. Further afield, outside of the floodplain, land is used for arable farming (1995 RCS). Land Use  To the north was the former Roman town of Billingford, and many fields are grassland, with hedgerows and pockets of woodland, where cropmarks indicate locations of former buildings, roads and other features.  500m to the southwest of the mid-reach point lies Swanton Morley Airfield and Robertson Barracks.  At the southern end of the reach there are weirs associated with the former paper mill.

 Swanton Morley Road and Worthing Road occur in close proximity to the river in the upper half of this reach. Traffic and Transport  The Dereham Road (B1147) crosses both the main river channel and the mill bypass channel at the downstream end of the reach. This road runs in close proximity to the bypass channel for approximately 200m.

Utilities  No detailed information has been compiled for this reach at this stage.

River  Work in recent years includes the repair of a breach on the TLHB approximately 900m upstream of Swanton Morley Mill weir structure. Maintenance

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Figure 3.3 – Environmental baseline for Reach 15 (Swanton Morley Reach)

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Table 3.7 - Baseline information specific to Reach 16 (Elmham Reach)

Environmental Baseline Information Feature

 Signs of water voles were noted, in surveys between 1997 and 2007, at Billingford Bridge (Wild Frontier Ecology, 2007). Ecology  White clawed crayfish have been recorded at the Black Water confluence and at Billingford in 1997 (EA database information) and in 2003 (EA, 2004). (Protected Species)  Otter have been recorded at Billingford Bridge between 1978 and 2000 (EA database information).  Bullhead have been recorded at North Elmham (1983) and d/s Billingford Bridge (1990-1997).

Ecology  SAC and SSSI units: (Statutory Unit 51: River Wensum. Designated Areas)

 Broads ESA. Ecology (Non- Statutory  County Wildlife Site 669 – Gravel Pits. This 4.6ha site consists of two eutrophic lakes formed within disused gravel pits near Swanton Morley. The larger Designated of the two lies to the north (adjacent to this reach), its banks support a few patches of common reed (Phragmites australis) but are mostly bare with scrub Areas) such as willow (Salix spp.). The smaller lake (adjacent to Reach 15) has a patchy marginal vegetation of reedmace (Typha latifolia) and is surrounded by willow scrub.

 Fisheries: Routine Environment Agency fisheries data is available for one site in this reach, downstream of Billingford Bridge (EA site code NOR21). Nine surveys have been conducted since 1986, the most recent in 2008. Fifteen species have been recorded in total, including both coarse and salmonid species, although trout (Salmo trutta) have not been recorded in the three most recent surveys (2006, 2007 and 2008). Of the nine species recorded in 2008, dace (Leuciscus leuciscus) and chub (Leuciscus cephalus) were the most numerically abundant species.  Two species of European interest, namely eel (Anguilla anguilla) and brook lamprey (Lampetra planeri), have been recorded in this reach.  Targeted roach (Rutilus rutilus) surveys conducted in March 2006 in a side-channel downstream of North Elmham Mill identified good aggregations of overwintering roach shoals (Environment Agency, 2007b). Ecology  Invertebrates: There is no routine Environment Agency invertebrate sampling site within this reach. (Fisheries,  Flora: The 1995 River Corridor Survey for this reach recorded in-channel plants including unbranched bur-reed, yellow water lily and perfoliate Invertebrates & pondweed together with sparse patches of fennel pondweed, horned pondweed, curled pondweed and water-crowfoot. Filamentous algae (Cladophora Flora) agg.) was frequently found. Further below the mill in-channel vegetation consisted of clumps or sparse coverings of curled pondweed, fennel and perfoliate pondweed, water-crowfoot, unbranched bur-reed, flowering rush and arrowhead. Shallow riffles supported horned pondweed and fennel pondweed.  Marginal areas were recorded as being generally poor in vegetation, with patches of water-cress, lesser water-parsnip and brooklime, but increasing downstream with reed sweet-grass and a clump of lesser water parsnip below the mill. Further downstream reed sweet-grass dominated bank vegetation, with water-cress and brooklime also present. The cut-off meander, east of the flooded pit, supported fennel pondweed and fan-leaved water crowfoot, Canadian pondweed, water starwort and common duckweed.  Upper bank areas generally supported great willowherb, nettle and thistles.

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Environmental Baseline Information Feature

Ecology  Mink scats were recorded at Billingford Bridge in 1999 (EA database information). (Invasive / Non-  Canadian pondweed was recorded downstream of North Elmham Mill (northern channel) (1995 RCS). Native Species)

 Broadleaved trees were noted along the TLHB below the mill (1995 RCS) consisting of alder, white willow, with other isolated trees including elder, hawthorn and ash. Ecology (Trees)  The 1995 RCS recorded alders, white and crack willows, osier, elder, hawthorn, ash, hazel and horse chestnuts. The old road crossing supported hawthorn, hazel, alder, oak and scrub.

 The upper reaches have been extensively altered for the construction of North Elmham Mill but this reach retains a formalised meandering planform. Geomorphology  Below the mill the 1995 RCS noted the river was broad, winding with embankments but retained a pool and riffle sequence with unvegetated mid-channel bars and water-crowfoot.

Previous  Billingford meander loop reconnection works were completed in 2000. Restoration Works

 According to the Environment Agency mapping, the indicative Flood Zone 3 extends across a wide area from North Elmham Mill to the end of the reach, particularly across the former gravel pits (http://maps.environment-agency.gov.uk). Flood Risk  The mill buildings are within Flood Zone 3.  The B1145 appears to be above modelled flood levels, including extreme flood event levels.

 The main settlements include North Elmham Mill and Mill House Farm, at the edge of North Elmham at the top end of the reach, and a single house d/s Human of the B1145 (mid-reach). Environment  No other settlements are present along this reach.  All angling rights in this reach are privately owned. For example, Worthing Pit Syndicate has rights to the TRHB at Worthing Pit.

 There are 7 listed buildings within 1km of this reach, including Church of St Margaret (II*) and the church of St Peter (I), Worthing Mill (II), Billingford Hall and other buildings in Billingford (II). Historic  The area is rich in records (over 60 Historic Environment Records and Past Scape items) for historical finds and recorded monuments. These range Environment from crop marks indicative of nearby Roman and Saxon settlements, Prehistoric, Bronze age, medieval and post-medieval finds or features, WW2 tank traps (a line of large concrete blocks d/s B1145 and various other features) and post medieval water meadows at Billingford.  References: Heritage Gateway and Listed Buildings Online web-based searches within 1km of the search point (at TG005200).

 Within the floodplain the dominant land uses are grazing land (improved/semi-improved grassland) and a disused gravel pit used for angling. Arable land Land Use predominates on the higher land outside the floodplain.  The 1995 RCS recorded mostly improved grassland with some amenity grassland and areas of standing water (flooded gravel pit).

Traffic and  Access to the river is limited to the east-west route of Billingford Road (B1145). Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 40

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Environmental Baseline Information Feature Transport  There is a private road leading to the properties at North Elmham Mill.

Utilities  No detailed information has been compiled for this reach at this stage.

River  No routine maintenance identified in this reach. Maintenance

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Figure 3.4 – Environmental baseline for Reach 16 (Elmham Reach)

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Plate 5 – Reach 14: River Wensum looking downstream to 3 Arch Bridge below site of Swanton Morley Mill (NGR TG 02045 08468, January 2011)

Plate 6 – Reach 14: Bypass channel at 2 Arch Bridge below site of Swanton Morley Mill (NGR TG 02150 18503, January 2011)

Plate 7 – Reach 14: Confluence of main channel and bypass channel downstream of Swanton Morley bridges (NGR TG 02035 18348, January 2011)

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Plate 8 – Reach 14: Downstream view showing large berm development on TLHB (NGR TG 02049 18160, January 2011)

Plate 9 – Reach 14: Field drain junction with the River Wensum (NGR TG 02089 18036, January 2011)

Plate 10 – Reach 14: Riparian woodland showing secondary channel confluence with primary flow route (NGR TG 02202 17707, January 2011)

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Plate 11 – Reach 14: Spring fed channel, one of many discharging at this location (NGR TG 02406 17593)

Plate 12 – Reach 14: High embankments at Castle Farm showing perched river channel (NGR TG 02739 17707, January 2011)

Plate 13 – Reach 14: General character of IDB drain on TLHB floodplain (NGR TG 03271 18201, January 2011)

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Plate 14 – Reach 14: Wensum valley viewed towards the south-east from Lime Kiln Road (NGR TG 03542 18379, January 2011)

Plate 15 – Reach 14: Penny Spot Beck confluence (NGR TG 04195 17528, January 2011)

Plate 16 – Reach 14: Phalaris berm on approach to overhanging tree cover on TLHB below Old Hall Farm (NGR TG 04124 17788, January 2011)

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Plate 17 – Reach 14: Significant enlargement of channel width on approach to Elsing Mill (NGR TG04398 17320, January 2011)

Plate 18 – Reach 14: View of island showing secondary channel confluence downstream of meander bend (NGR TG 04823 17482, January 2011)

Plate 19 – Reach 14: Sluice on Elsing Mill bypass channel with vertical lift gates fully open (NGR TG 04939 17595, January 2011)

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Plate 20 – Reach 14: Bypass channel out of bank event downstream of sluice with inundated floodplain in background (NGR TG 04920 17607, January 2011)

Plate 21 – Reach 14: Approach to Elsing Mill with bypass sluice to the left of picture (NGR TF 04943 17592, November 2010)

Plate 22 – Reach 15: Recent ditch clearance work on TLHB floodplain (NGR TG 00767 19668, January 2011)

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Plate 23 – Reach 15: Downstream view from river crossing at Riverside Farm (NGR TG 00797 19552, January 2011)

Plate 24 – Reach 15: Fish fry bay completed in 2005 opposite Burgh Common (NGR TG 01047 19445, January 2011)

Plate 25 – Reach 15: Fishing platforms and boardwalk at Burgh Common (NGR TG 01321 19316, January 2011)

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Plate 26 – Reach 15: Downstream view showing gravel pit lake on TLHB floodplain and approximate location of in-stream gravel works undertaken in 2005 on the River Wensum (NGR TG 01592 19340, January 2011)

Plate 27 – Reach 15: River Wensum (foreground) and pit lake (background) showing limited freeboard at time of visit (NGR TG 01910 19394, January 2011)

Plate 28 – Reach 15: Sandbag line to protect against breach of River Wensum into adjacent fishing lakes on TRHB floodplain (NGR TF 97518 25868, November 2010)

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Plate 29 – Reach 15: View across valley towards IDB channel on TLHB floodplain (NGR TG 02171 19072, January 2011)

Plate 30 – Reach 15: Approximate location of fry refuge created in 2006 (NGR TG 02167 18898)

Plate 31 – Reach 15: Upstream view of River Wensum from below bypass channel off-take and weir (NGR TG 02185 18687, January 2011)

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Plate 32 – Reach 15: Bypass channel weir and confluence of IDB channel on right (NGR TG 02215 18653, January 2011)

Plate 33 – Reach 16: North Elmham Mill bypass channel (NGR TG 00321 20381, January 2011)

Plate 34 – Reach 16: Main river and bypass confluence downstream of mill (NGR TF 98201 25222, November 2010)

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Plate 35 – Reach 16: View towards Billingford Road bridge showing Glyceria berm development on both banks (NGR TG 00485 20308, January 2011)

Plate 36 – Reach 16: IDB channel and main river confluence immediately upstream of Billingford Road bridge (TG 00448 20187, January 2011)

Plate 37 – Reach 16: Downstream view towards old road bridge crossing (removed) (NGR TG 00453 20120, January 2011)

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Plate 38 – Reach 16: Black Water / Wendling Beck confluence (NGR TG 00527 20055, January 2011)

Plate 39 – Reach 16: Black Water / Wendling Beck (NGR TG 00527 20055, January 2011)

Plate 40 – Reach 16: Mature berm feature on TRHB (NGR TG 00656 20054, January 2011)

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Plate 41 – Reach 16: Site of bank erosion of TRHB viewed upstream (NGR TG 00527 20055, January 2011)

Plate 42 – Reach 16: Billingford meander loop reconnection (NGR TG 00697 19998, January 2011)

Plate 43 – Reach 16: Downstream view towards reach boundary location (Reach 16/15) (NGR TG 00697 19998, January 2011)

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Plate 44 – Reach 15: River Wensum viewed downstream towards Riverside Farm (NGR TG 00740 19807, January 2011)

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4. Consultation 4.1 Introduction This chapter summarises comments received from key statutory stakeholders and the public. A drop-in session covering this river unit was held at Fakenham Racecourse in September 2009. In addition, one-to-one interviews have been conducted with a number of stakeholders in this unit. 4.2 Consultation with key stakeholders Since 2008, the project team has been communicating with various internal and external stakeholders during the feasibility assessment and the Environment Agency has contacted key staff within different organisations regarding various EIA and planning matters for the River Wensum as a whole. Table 4.1 summarises the responses of these organisations. It should be noted that many of these responses are generic, rather than specific to this particular unit. Table 4.1 - Consultation undertaken to date (August 2010)

Date Nature of Consultation / Consultee Responses Organisation Consulted Statutory Consultees Joint meeting with officers from planning and environment from each council to introduce the restoration strategy, proposals developed for other units and planning and environmental issues. Officers were assured that the KLWNDC and NNDC September 2009 restoration strategy would not increase flood risk to people and property. Officers showed overall interest and support but further consultation would be needed in future, including the need to confirm permitted development rights. The first meeting presented the objectives of the Strategy. The IDB did not disagree with the overall proposals but expressed concern over Environment Agency maintenance on the main river. Norfolk Rivers IDB / September 2008 The second meeting discussed a number of potential joined Water Management and May 2009 up approaches to targeted river maintenance. This Alliance collaborative approach would see a shift to river maintenance practices which are likely to benefit both river restoration and angling interests whilst addressing some of the key landowner concerns. A reply was received in April 2009. The landscape team Norfolk County would like further EIA assessment to make a more detailed March 2009 Council – Landscape appraisal of potential impacts (good and bad) to the landscape character and visual amenity of the River Wensum. Key staff were briefed on the proposal, including the issue of winning gravels from site or from an external source e.g. Norfolk County existing gravel pit site. Council provided their “in principle” November 2008 Council – Minerals support for restoration and indicated that if gravels had to be brought to site from elsewhere then planning permission may be required. Internal meeting held in November 2008 to raise awareness of project and to identify issues of implementation. The Development and Flood Risk Team has confirmed that a Internal Environment Flood Risk Assessment will be required. The Flood Risk November 2008 Agency Functions Assessment will have to show: 1) Any changes in the extent of floodplain. 2) Any changes in depth of flooding. 3) Likely impact on any properties.

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Date Nature of Consultation / Consultee Responses Organisation Consulted Recognises the need to implement a recommended option to Natural England 2008 deliver ‘favourable’ condition to the SSSI.

The initiative is a partnership between Defra, Natural England England Catchment and the Environment Agency. Ongoing consultations with Sensitive Farming April 2008 local Catchment Sensitive Farming Officer to identify specific Delivery Initiative problems from diffuse pollution from agriculture. Non-Statutory Consultees Landowners Ongoing All landowners were invited to the Drop-in Session to inform them of the likely timetable for the Feasibility Report. Since that time landowners have been contacted with regard to access for field walk over surveys. This prompted some dialogue, the results of which have been incorporated into the outline designs. It is expected that dialogue will continue where opportunities arise to change the river and/or its management to benefit ecology. Contact with the wider public, including landowners, is achieved with e-mailing of the regular River Wensum Restoration Strategy Newsletter. This was a joint presentation with a representative from the England Catchment Sensitive Farming Delivery Initiative Broads Forum October 2008 highlighting the benefits of reducing sediment input into the Wensum. Another key message was the need to prevent silt ingress into river reaches downstream of restoration sites. Presentation was given to the Steering Group which focused on the benefits of re-establishing the hydrological relationship Norfolk Biodiversity January 2007 between river and floodplain and the potential benefits to BAP Partnership habitat. The Group was enthusiastic, but as a policy they do not express support for specific projects. The meeting focused on understanding their objectives for the Wensum Valley Trust July 2008 Wensum Valley, particularly in relation to river restoration. Norfolk Anglers The presentation focused on the synergy between river Conservation May 2008 restoration and benefits for fisheries. Support was expressed Association for implementation of the Strategy. The meeting brought the National Farmers Union up to speed with the development of the Strategy and gave them an April 2008 understanding of what we are trying to achieve.

National Farmers

Union Project staff attended an NFU organised meeting to discuss

progress with a number of Wensum issues, including diffuse January 2011 pollution, access on the river, river restoration and water resources. Waterbodies BAP The Group expressed a general support for the October 2007 Topic Group implementation of the Strategy. River Restoration Presentation focused on how the Strategy was developed, the Centre Annual April 2007 issues that it will address and how we intend to take it Network Conference forward.

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4.3 Drop-in session September 2009 A drop-in session about the implementation of the River Wensum Restoration Strategy was held on 8th September 2009 at Fakenham Racecourse. The objectives of the session were:  To engage with people who live within the vicinity of the river, and are likely to be affected by the proposed restoration works.  To identify the key environmental concerns / constraints and opportunities with respect to strategic options available for implementing river restoration.  To gain an insight into local knowledge of the river.  To help identify acceptable options, that are environmentally, technically and economically feasible, to deliver ‘unfavourable recovering’ or ‘favourable’ ecological condition. The drop-in was designed to ensure that the local landowners, parish councillors and interested stakeholders had an opportunity to comment and present their views on river restoration. A total of 64 people attended the drop-in session. Attendees recognised that there has been a general decline in the river’s condition, particularly its ecological character and many agreed that the river is in need of some work to improve its condition. Comments recorded on the feedback forms completed by attendees related to:  Poor maintenance of the river including inappropriate weed cutting activities.  Continued neglect by river authorities, past and present.  The failure to instigate a planned maintenance system.  The lack of regular dredging.  Concerns about increasing flood risk.  How compatible new restoration measures will be on existing structures, such as the mills, which are of importance for local heritage and landscape character.  The financial costs of the proposed measures.  The need to explore the possibilities of utilising mill structures to generate electricity and the compatibility of hydropower schemes with river restoration.  The lack of public access to the river, in particular where restoration is proposed. Many attendees were not convinced by the restoration measures presented and requested that they are consulted when further details are available. Particular concerns related to necessity and the economic justification for restoration measures. 4.4 Future consultation Some specific constraints and opportunities identified following the Atkins site visits on this unit are considered below, and include, but are not limited to: Constraints:  Confinement: Although access is generally good in this unit, Reach 15 and the downstream section of Reach 16 are confined spatially by lakes, thereby reducing the potential for improvements through gross planform change.  Ecology: The environmental impact of improving habitats for some flora and fauna could be detrimental for others.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

 Function: Significant over widening immediately upstream of Elsing Mill reduces options available to improve condition status. Opportunities:  Ecology: Site won materials can be used to create and improve in-stream conditions. This includes felling of trees to be used as large woody debris, and to reduce shading and so encourage vegetated berm development.  Ecology: Reconnections and realignment works will improve the availability of fish habitat, potentially increasing recruitment.  Ecology: Reconnections to the floodplain may potentially improve condition of terrestrial SSSI units in Reaches 14 and 15.  Ecology: The value of previously completed restoration works can be complemented by new measures that join up existing restored habitats.  Flood risk: Additional flood storage capacity created by realignment and embankment lowering works could potentially reduce downstream flood risk. Further consultation with local landowners and internal and external stakeholders will be undertaken as restoration schemes are taken forward into detailed design.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

5. Multi-Criteria Analysis Options Appraisal 5.1 Introduction A Multi-Criteria Analysis (MCA) system, based on weighted numerical scoring, has been used to help select appropriate restoration options / measures for each river reach. This was considered necessary to ensure that a transparent, defendable and replicable technique of selecting options / measures was applied. This chapter describes the process by which the MCA tool was designed and subsequently applied. A number of options have been considered which could be implemented individually, or as a group, to restore ‘unfavourable recovering’ or ‘favourable’ condition to the River Wensum. The chapter concludes by presenting the most favourable scoring options / measures for the study reaches. Costs have been excluded from this MCA process and are considered subsequently in Chapter 7. Further details of the MCA process (MCA technical note and MCA table) can be found in Appendix A to this report. Table 5.1 provides an overview of the steps involved in constructing and applying the MCA tool, and Section 5.2 provides more detail. Table 5.1 - Overview of the process by which the MCA was constructed and applied A Constructing the MCA Tool 1 Identification of options / measures

2 Selection of success criteria 3 Ranking of success criteria 4 Setting up the MCA table B Applying the MCA Tool (Spreadsheet) to Specific Reaches 1 Is the option / measure applicable to the reach? If no, discard. 2 Work through each criterion by option / measure. 3 Apply weighting and determine total weighted score (TWS) 4 Mill structure measures: Apply the best scoring measure. Other measures: Undertake statistical analysis and discard measures scoring 5 below lower limit.

Other measures: Apply remaining measures in order of highest to lowest 6 scoring. 7 Gravel works: Apply best scoring measure.

5.2 Constructing the MCA tool The MCA Table provides the framework for the options appraisal process, and scores the degree to which all the proposed restoration options / measures meet the defined criteria. The initial stage in the options appraisal was the construction of the Table, which involved defining the options / measures to be considered, and defining the criteria against which the options / measures are evaluated. Following the construction of the Table, it was applied as a tool to determine the highest scoring options / measures for each reach.

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5.2.1 Identification of options / measures A generic list of all restoration options / measures possibly applicable to the River Wensum was generated through the following activities:  Document review: All options and restoration measures recommended in the RWRS and the Geomorphological Appraisal were considered and all were included in the final list of options. Table 5.2 lists the measures recommended in these two reports. Table 5.2 - Restoration measures recommended in previous studies Reach Geomorphological Appraisal River Wensum Restoration Strategy Fix sediment ingress points and targeted desilting of reach. Remove embankments and use material to narrow channel and raise bed elevations. Establish run / glide habitat and restore channel dimensions All works must integrate with lowering of using dimension from old course of structures at Elsing and Swanton Morley Wensum to inform design. Mills and associated river works. De-silt Reoccupy old course. channel just upstream of Swanton Morley 14 structures, physically narrow and augment Use woody debris structures to establish bed with gravels. Remove embankments to scour pools and flow / morphological reconnect the river to its floodplain and diversity. Establish patchy wooded riparian encourage development of marginal / margin. bankside vegetation. Ensure STW not discharging solids. Reduce water levels at mill weir. Establish monitoring programme.

All works must integrate with lowering of structures at Swanton Morley Mill and Fix sediment ingress points and desilt river associated river works and must link with bed. Use dredging to reduce channel width previously completed schemes. De-silt and establish emergent riparian vegetation. channel just upstream of Swanton Morley Establish patchy riparian woodland and structures and augment bed with gravels. 15 debris recruitment. Augment bed levels by Encourage channel to narrow naturally by using dredged gravels from bank. Reduce developing marginal / bankside vegetation. low embankments (dredging) to enable Plant trees on outer bends to prevent reconnection with the floodplain. breaching into gravel pits. Introduce coarse woody debris structures in the downstream section of the reach to encourage scour.

All works must integrate with lowering of Remove mill weir, augment bed with gravel structures at Swanton Morley Mill and North to create run / riffle and raise water levels. Elmham Mill and associated river works. Assist narrowing and install woody debris Also must link with the completed meander 16 structures to scour pools. Establish patchy loop connection at Billingford and take flood wooded riparian margin. risk into consideration. Develop marginal / Monitor silt / sand input from Black Water / bankside vegetation and augment bed with Wendling Beck. gravels. Preferably, remove embankments to reconnect river to its floodplain.

Consultation: This took the form of a public drop-in session, as described in Chapter 4 of this report. Consultation with authorities such as Breckland District Council and King’s Lynn and West Norfolk District Council was also undertaken. Workshop: An MCA workshop, attended by the Environment Agency, Natural England and Atkins, was held on 29th January 2009 with the purpose of working through the MCA approach. From the above sources, six main option groups were identified namely ‘Do nothing’, ‘Do minimum’, ‘Targeted maintenance’, ‘Continue as present’, ‘River restoration ’ and ‘Alternative

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

options’. These are explained in Table 5.3. Appendix A provides further information regarding the options. Table 5.3 - Options identified for restoration on the River Wensum

No. Option Description No maintenance to main river or IDB channels. No restoration to G1 Do nothing any channels or floodplain. No operational activities such as weed cutting. No maintenance to main river or IDB channels. Opportunistic restoration in certain areas (e.g. trees may be felled where G2 Do minimum appropriate thereby reducing channel shading). No operational activities such as weed cutting. Reduced maintenance to include only reactive activities e.g. removal of debris posing an immediate flood risk or removal of silt G3 Targeted maintenance in specific locations. Mitigation for activity in the form of small scale restoration. Limited operational activities e.g. sluice management for high flows. Continuation of existing activities which includes maintenance (debris removal, bank repairs, selected desilting and selected weed G4 Continue as present cutting). Undertaking small scale, opportunistic restoration activities. Continuation of operational activities such as sluice management during high flows. Active restoration measures of which 21 such measures have been identified and grouped into three sub-groups namely ‘Mill G5 River restoration structures’, ‘Gravel works’ and ‘Other’. See Appendix A for a full list of these measures. Three options have been considered within this group, namely ’Increasing main river maintenance’, ‘Increased main river and IDB G6 Alternative options maintenance’, and ‘Mills re-used for hydro-power’. These are explained further in Appendix A.

Three groups of ’measures’ have been defined under the option G5 (see Table 5.4 for full details). These include:  Various works around mill structures including changes to operating protocol, lowering mill sill levels and constructing / utilising existing bypass channels.  Various gravel works including large scale bed raising.  Other measures.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

Table 5.4 - Description of river restoration measures as defined under option G5 Group Restoration Measure Description Modify existing mill operating protocols to ensure Improve operation water level management is in line with SSSI protocols management. Mill Structure Works Remove flow control Remove all sluice control mechanisms and allow These works mechanisms the river to be free flowing. Lower the level of the mill sill to reduce the extent need to be Lower mill sill levels undertaken first of backwater in low flows. Construction of channel around mill to split flows to ensure the Create bypass channel to allow fish passage and continuity of stream success of any around mill subsequent processes. Construction of fish pass alongside mill structure measures Install fish pass to enable free passage of fish upstream. Remove mill structure Remove entire mill structure. Creation of short lengths of full width raised bed, Gravel Works Gravel glides dressed in gravel, to create variation in flow and Need to be habitat for fish and invertebrates. considered (and Creation of short lengths of raised gravel bed with constructed) Gravel glides and hurdles made from post and faggots to trap after Mill transverse hurdles suspended sediment thereby extending the Structure Works length of the glide over time. have been Creation of extended lengths of full width raised completed Bed raising bed – to reduce water depth and allow characteristic plant communities to develop. Fencing constructed landward of the river bank to Fencing prevent bank erosion from the impacts of cattle grazing. Tree planting to cast shade over the water to control macrophyte growth, provide cover for fish, Tree planting and to develop erosion resistance from root reinforcement. Selective felling or lopping to provide light onto Tree thinning the water to encourage macrophyte or emergent plant growth, and generate arisings for deflectors. Other Deflector (using Large Downstream pointing LWD placed at the Measures Woody Debris (LWD) upstream side of deflector to create flow diversity; and filled in with brush in-filled downstream with brush to promote silt These need to mattress) deposition and plant growth. be considered Removal of dredging based informal after Mill Lower spoil embankments to allow out of bank flow across Structure embankments the floodplain, and back into the river. Use of Works and arisings for riffles / general bed raising if needed. Gravel Works Horizontal lowering of bank top up to 1/2 channel have been width to increase flood flow capacity and Berm creation identified generate arisings for bed raising where no embankments. Backchannels – Utilizing existing wet features by connecting them reconnections to IDB to the river to create essential habitat for fish and and existing field drains other fauna. Creating habitat where no other water bodies Backchannels – create exist e.g. dog-leg with downstream end open and new features upstream end fed by percolation. Full depth excavation from bank top to increase Channel realignment to lateral variation in planform either one bank or increase river sinuosity both with arisings used to infill opposite bank.

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5.2.2 Selection of success criteria ‘Criteria’ refer to the various standards against which the proposed options / measures are evaluated. A range of criteria (12 in total) were defined during a workshop between Atkins, Environment Agency and Natural England in January 2009. These criteria have been grouped under the following three broad headings: 1. Ecology: This includes criteria relating to legally protected ecology, such as compliance with the SSSI designation, as well as that which is not legally protected, but where the proponents of the works still have a responsibility to safeguard and improve ecological value of the site. Three of the criteria within this group relate to three levels of legal designations, and the final criterion covers all non-legal responsibilities.

2. Project delivery: This considers compliance with the objectives of the RWRS and takes into account stakeholder opinion. Hence compliance/agreement with requirements of statutory and non-statutory stakeholders is considered.

3. Technical: This group considers delivery of the technical aspects of the RWRS objectives including technical feasibility, geomorphic form, flood risk and climate change.

All criteria and accompanying descriptions are provided in Table 5.5. 5.2.3 Ranking success criteria While all of the defined criteria groups are significant, it is acknowledged that some are more so than others. For example, ecology is the main driver of the project and the primary objective is to improve the ecology of the River Wensum. Hence, compliance with these criteria can be considered as more important than, for example, technical considerations and hence a weighting system has been applied to these groups. Similarly, different criteria within a single group such as ‘Ecology’ are not necessarily of equal importance. For example, the criterion ‘Compliance with National Designation’ (such as SSSI), which falls within the ‘Ecology’ group, is the main driver for this project, and hence compliance with this criterion is considered essential for achieving project objectives. The criterion ‘Contribution to overall ecology’ would be considered less important. Hence, a similar weighting system has been applied to individual criteria within the three groups. Professional judgement was applied in determining the numerical weighting for each criteria group and each criterion. A weighted score between zero and one was applied and agreed to in the MCA workshop. An ‘effective weighting factor’ for each criterion was calculated by multiplying the group criteria weighting and the individual criteria weighting. Table 5.5 presents the criteria and applied weightings and Appendix A provides a detailed explanation for the weighting of criteria.

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Table 5.5 - Criteria defined for the MCA

Group Weighting Effective (group Criterion Description / Example Within Weighting weighting) Group Factor SSSI requirements for the Compliance with river e.g. improved flow 1 1 national designation regime, water quality and channel form. SAC requirements Compliance with including maintaining international 0.8 0.8 favourable habitat for EU designation Ecology designated species. (1) BAP requirements such as Compliance with maintaining flora and fauna regional / local 0.6 0.6 characteristic of chalk designations rivers. Compliance with the Contribution to Environment Agency’s 0.5 0.5 overall ecology general duty to further conservation Meeting objectives of the Compliance with RWRS as well as the strategy (RWRS) 1 0.9 specific reach objectives recommendations. Stakeholders include Compliance with Environment Agency, statutory Natural England, Breckland 0.9 0.81 Project stakeholders District Council, and delivery Norfolk County Council. (0.9) Agreement with non- Angling clubs, land owners statutory 0.9 0.81 and tenants. stakeholders Consideration of or improvements to Human environment 0.4 0.36 archaeology, landscape, and recreation value. Consideration of design, Technical feasibility & construction process, 1 0.8 practicality commercial risk, and maintenance. Geomorphic form Consideration of the shape 1 0.8 Technical and function and flow of the river. (0.8) Consideration of the impact Flood risk 1 0.8 of restoration on flood risk. Considers the robustness Climate change and of the measures in terms of 0.8 0.64 sustainability future flood risk and carbon footprint.

5.2.4 Setting up the MCA Table Defining the scoring system The MCA Table lists all of the options / measures against the 12 defined criteria and a score is allocated depending on the degree to which the individual options / measures comply with the criteria.

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The term ‘relevance’ is used to describe where a particular option / measure complies with the criteria or brings about betterment of the features pertaining to those criteria. The term ‘detriment’ is used where a particular option / measure does not comply with the criteria or results in an adverse change to a particular feature pertaining to those criteria. A five point scoring system is utilised with +2 allocated if the option / measure is of high relevance and -2 allocated where the option / measure is of high detriment. These terms are presented in Table 5.6. Table 5.6 - Scoring system defined for the Multi-Criteria Analysis

Score Description +2 High relevance +1 Low relevance 0 Neutral

-1 Low detriment -2 High detriment

These are applied as ‘raw scores’. From here, a ‘weighted score’ is derived by multiplying the ‘raw score’ by the ‘effective weighting factor’. A ‘total weighted score’ for an individual option / measure is derived by summing all of the ‘weighted scores’ for that option / measure. The consideration of costs was deliberately excluded from the MCA analysis so as not to discriminate against any options or measures, and so determine the best technical solution irrespective of cost. 5.3 Using the MCA Tool The MCA tool has been applied to each of the reaches separately on a reach by reach basis. The following main steps were undertaken:  The applicability of the option / measure was considered. Where the option / measure is not applicable (e.g. ‘Changing primary and secondary channels’ may not be applicable if no secondary channel exists) then this option / measure has been discarded.  The remaining criteria were then worked through for one option / measure at a time and raw scores allocated. Working through by option / measure allowed greatest consistency of scoring.  Weightings were applied to the raw scores to generate weighted scores.  Total weighted scores (TWS) were calculated for each option / measure by summing all of the weighted scores.  Statistical analysis was applied to the scores within the ‘River Restoration’ (G5) options category. Those scoring below a defined statistically lower limit were discarded. Appendix A provides further information on the statistical methods.  The measures with the highest TWS represent the preferred suite of options and associated measures for that specific reach. These were applied, in their scored order, for designing a preferred restoration plan for the reach. The results of the MCA analysis for Reaches 14 to 16 are displayed in Tables 5.7 to 5.9.

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Criteria

River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

Table 5.7 - Results of MCA for Reach 14 (Elsing Reach) River Wensum Multi Criteria Analysis River 51 Criteria Group Ecology [A] Project Delivery [B] TechnicalUnit: [C] Wensum Group weighting 1 0.9 0.8 Reach: 14 Elsing Human Technical Geomorphic Flood Risk Climate Total Rank order 4830m Individual weighting within group 0.8 1 0.6 0.5 1 0.9 0.9 0.4 1 1 1 0.8 Length: Option / Compliance Compliance Compliance Contribution Compliance ComplianceEnvironment: Agreement Feasibility form & [C.c] Change & Raw measure with with with to overall with Strategy Archaeology;with with& function [C.b] sustainability Score applicable to International National Regional/Local ecology [A.d] objectives Statutorylandscape; Non ‐practicalitystatutory [C.d] (highest reach Designation Designation designation (Wildlife & Stakeholdersrecreation Stakeholders [C.a] possible (SAC) [A.a] (SSSI) [A.b] (BAP) [A.c] Fisheriesowners; & (EA; NE; BDC;[B.d] (anglers; score 24) River occupiers)Form & NCC) [B.b] Process) [B.c][B.a] Individual w eighting factor = 0.8 1 0.6 0.5 0.9 0.81 0.81 0.36 0.8 0.8 0.8 0.64 Option No. Option / measure G1: Do Nothing: No maintenance or restoration: raw score Y 0 111‐20‐2 0201 02 Weighted score 010.60.5‐1.8 0 ‐1.62 0 1.6 0 0.8 0 1.08 G2: Do Minimum: minimal restoration: raw score Y 1 111‐11‐1 1110 06 Weighted score 0.8 1 0.6 0.5 1 ‐0.9‐1 0.81 ‐102‐0.81 0.36 0.8‐11 0.8 0‐1 0 ‐5 3.96 G3: Raw score Y Weighted scoreTargeted Maintenance: ‐0.8 1‐1 11112012110‐0.6 0 ‐0.9 ‐0.81 ‐0.81 0 1.6 ‐0.8 0.8 ‐0.64 12‐3.96 6 G5: Rive r Re sWeighted tor ation score 0.8 1 0.6 0.5 0.9 1.62 0 0.36 1.6 0.8 0.8 0 8.98 G5a M illG4: Structures:Continue as present: raw score Y ‐1 ‐1 ‐10‐ 5.1m Mill structures - improve operability + protocols: raw score Y 0 100112111109 w eighted score 0 1 0 0 0.9 0.81 1.62 0.36 0.8 0.8 0.8 0 7.09 5.2m Mill structures - remove flow control mechanisms: raw score Y 0 10011‐1 ‐1210 04 w eighted score 0 1000.90.81‐0.81 ‐0.36 1.6 0.8 0 0 3.94 5.3m Mill structures - low er mill sills levels Y 1 11121‐2 ‐1 ‐21 1 04 Weighted Score 0.8 1 0.6 0.5 1.8 0.81 ‐1.62 ‐0.36 ‐1.6 0.8 0.8 0 3.53 Mill structures – bypass channels Y 5.4m 2 2121111‐11 1 113 4 Weighted Score 1.6 2 0.6 1 0.9 0.81 0.81 0.36 ‐0.8 0.821 0.8 0.64 0 19.52 6 Weighted Score 5.5m Fish passes Y 2 21112101.6 2 0.6 1 0.9 0.81 ‐1.62 ‐20‐0.36 ‐1.6 0 0.8 1 09 0.64 4.77 G5b Gravel works: Weighted Score 1.6 2 0.6 0.5 0.9 1.62 0.81 0 ‐1.6 0 0 0.64 7.07 5.7g Gravel glides Y 5.6m Mill structures - remove all Y 2 212110 10022111001‐2 ‐1 ‐ 9 9 w eighted score 0 1 0 0 1.8 1.62 0.81 0.36 0.8 0 0 0.64 7.03 5.8g Gravel glides + transverse hurdles: raw score N 0 w eighted score 0 00000000000 0 5.9g Bed raising (large scale) Y 1 0112101‐11‐117 Weighted Score 0.8 0 0.6 0.5 1.8 0.81 0 0.36 ‐0.8 0.8 ‐0.8 0.64 4.71 G5c Other: 5.10 Fencing: Raw Score Y 0 011210‐1200 06 12L Weighted Score 0 0 0.6 0.5 1.8 0.81 0 ‐0.36 1.6 0 0 0 4.95 5.11 Tree planting on top of bank: raw score Y 0 011111120019 10 Weighted score 0 0 0.6 0.5 0.9 0.81 0.81 0.36 1.6 0 0 0.64 6.22 5.12 Tree thinning: raw score* Y 0 001211120008 0 11 w eighted score w eighted score 0 0 0 00000000000 0.5 1.8 0.81 0.81 0.36 1.6 0 0 0 5.88 0 5.13 Deflector5.15 (using ChannelLWD and Re-sectioning filled in w ith brush mattress) Y N1 2111211110113 0 3 w eighted score w eighted score 0.8 20 0.6 00000000000 0.5 0.9 1.62 0.81 0.36 0.8 0.8 0 0.64 9.83 0 5.14 Low er spoil5.16 embankments Berm creationN Y 1 2122211120116 1H w eighted score 0.8 2 0.6 1 1.8 1.62 0.81 0.36 0.8 1.6 0 0.64 12.03 Backw aters – reconnections to IDB, field drains Y 5.17 1 1120101211213 5 w eighted score 0.8 1 0.6 1 0 0.81 0 0.36 1.6 0.8 0.8 1.28 9.05 5.18 Backw aters - new Y 1 1110111111111 8 w eighted score 0.8 1 0.6 0.5 0 0.81 0.81 0.36 0.8 0.8 0.8 0.64 7.92 5.19 Channel realignment Y 1 2220102021215 2H w eighted score 0.8 2 1.2 1 0 0.81 0 0.72 0 1.6 0.8 1.28 10.21 5.20 Changing primary and secondary channels (e.g. Ryburgh) Y 0 011021010006 13L w eighted score 0 0 0.6 0.5 0 1.62 0.81 0 0.8 0 0 0 4.33 5.21 Low er embankments Y 0 12221‐2 2211 113 6.03 Weighted Score 0 1 1.2 1 1.8 0.81 ‐1.62 0.72 1.6 0.8 0.8 0.64 8.75 7 6.2 Increase main river & IDB channel maintenance: raw score Y ‐2 ‐2 ‐2 ‐20‐10‐12‐20‐2 ‐12 Weighted score G6: Alternative Options ‐1.6 ‐2 ‐1.2 ‐10‐0.81 0 ‐0.36 1.6 ‐1.6 0 ‐1.28 ‐8.25 6.3 Mill Structures - reinstatement & maintenance + hydropow er Y ‐1 ‐2 ‐2 ‐2 ‐2 ‐210‐1 ‐1 ‐1 ‐1 ‐14 6.1 Increase Main river maintenance: raw score Y ‐1 ‐1 ‐1 ‐20‐2 ‐1 ‐12‐10‐1 ‐9 Total Score Weighted Score ‐0.8 ‐2 ‐1.2 ‐1 ‐1.8 ‐1.62 0.81 0 ‐0.8 ‐0.8 ‐0.8 ‐0.64 ‐10.65 Weighted score ‐0.8 ‐1 ‐0.6 ‐10‐1.62 ‐0.81 ‐0.36 1.6 ‐0.8 0 ‐0.64 ‐ 18 31 19.8 26 32.4 36.2 2 13.6 34 19.8 13.4 14.76 Key Score Description Mean: 8.05 2High Relevance SD: 2.25 ‐1Low Detriment Low imp: <5.8 1Low Relevance ‐2High Detriment 0Neutral High imp: >10.3 Notes: Embankments throughout this reach are considered as formal embankments constructed to maximise water volume storage for historic milling activities at Elsing Mill and have therefore been scored under 5.21 Lower Embankments only

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Criteria

River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

Table 5.8 - Results of MCA for Reach 15 (Swanton Morley Reach) River Wensum Multi Criteria Analysis River 51 Criteria Group Ecology [A] Project Delivery [B] TechnicalUnit: [C] Wensum Group weighting 1 0.9 0.8 Reach: 15 Swanton Human Technical Geomorphic Flood Risk Climate Total Total Rank order 2520m Individual weighting within group 0.8 1 0.6 0.5 1 0.9 0.9 0.4 1 1 1 0.8 Length: Option / Compliance Compliance Compliance Contribution Compliance ComplianceEnvironment: Agreement Feasibility form & [C.c] Change & Raw weighted measure with with with to overall with Strategy Archaeology;with with& function [C.b] sustainability Score score applicable to International National Regional/Local ecology [A.d] objectives Statutorylandscape; Nonpracticality‐statutory [C.d] (highest reach Designation Designation designation (Wildlife(anglers; & Stakeholdersrecreation Stakeholders[C.a] possible (SAC) [A.a] (SSSI) [A.b] (BAP) [A.c] Fisheriesowners; & (EA; NE;[B.d] BDC; score 24) Riveroccupiers) Form & NCC) [B.b] Process)[B.c] [B.a] Individual w eighting factor = 0.8 1 0.6 0.5 0.9 0.81 0.81 0.36 0.8 0.8 0.8 0.64 Option No. Option / measure 8.58 G1: Do Nothing: No maintenance or restoration: raw score Y ‐1 ‐1 ‐1 ‐1 ‐2 ‐2 ‐202‐1 ‐1 ‐1 ‐11 G2: Do M inim um : minimal restoration: raw score Y 0 001‐1 ‐1 ‐1 1110 12 Weighted score ‐0.8 ‐1 ‐0.6 ‐0.5 ‐1.8 ‐1.62 ‐1.62 0 1.6 ‐0.8 ‐0.8 ‐0.64 ‐ Weighted score 0000.5‐0.9 ‐0.81 ‐0.81 0.36 0.8 0.8 0 0.64 0.58 G3: Targeted Maintenance: Raw score Y 0 100111021119 9 Weighted score 0 1 0 0 0.9 0.81 0.81 0 1.6 0.8 0.8 0.64 7.36 G4: Continue as present: raw score Y ‐1 ‐1 ‐10‐1 ‐2 ‐1 ‐12‐1 ‐1 ‐1 ‐9 Weighted score ‐0.8 ‐1 ‐0.6 0 ‐0.9 ‐1.62 ‐0.81 ‐0.36 1.6 ‐0.8 ‐0.8 ‐0.64 ‐6.73 G5: Rive r Re s tor ation G5a M ill Structures: 5.1m Mill structures - improve operability + protocols: raw score N 0 w eighted score 0 00000000000 0 5.2m Mill structures - remove flow control mechanisms: raw score N 0 w eighted score 0 00000000000‐22 1 213 0 Weighted Score5.3m Mill structures - low er mill sills levels0.8 Y 11 0.6 11110000110 1 0.9 1.62 0.81 0.36 ‐1.6 1.6 0.8 1.28 9.17 7 5.5m Fish passesWeighted Score Y 1 11102110.8 1 0.6 0.5 0.9 0 0‐11 0 0 1 0.8 1 0.810 0 5.4 Weighted Score Mill structures – bypass channels0.8 Y 1 0.6 0.5 0 1.62 0.81 0.36 ‐0.8 0.8 0.8 0.64 7.13 5.4m 1 1121211 5.6m Mill structures - remove all Y 1 212120‐1 ‐12 1 212 4 Weighted Score 0.8 2 0.6 1 0.9 1.62 0 ‐0.36 ‐0.8 1.6 0.8 1.28 9.44 G5b Gravel works: 5.7g Gravel glides Y 2 2212221120118 1H w eighted score 1.6 2 1.2 0.5 1.8 1.62 1.62 0.36 0.8 1.6 0 0.64 13.74 5.8g Gravel glides + transverse hurdles: raw score Y 1 1111110110110 w eighted score 0.8 1 0.6 0.5 0.9 0.81 0.81 0 0.8 0.8 0 0.64 7.66 5.9g Bed raising (large scale) N 0 Weighted Score 0 00000000000 0 G5c Other: 5.10 Fencing: Raw Score Y 1 01110‐1 0210 06 12L Weighted Score 0.8 0 0.6 0.5 0.9 0 ‐0.81 0 1.6 0.8 0 0 4.39 5.11 Tree planting on top of bank: raw score Y 1 0112101210111 8 Weighted score 0.8 0 0.6 0.5 1.8 0.81 0 0.36 1.6 0.8 0 0.64 7.91 5.12 Tree thinning: raw score Y 1 011110020007 11 w eighted score 0.8 0 0.6 0.5 0.9 0.81 0 0 1.6 0 0 0 5.21 8.27 5.13 Deflector (using LWD and filled in w ith brush mattress) Y 5.16 Berm creation1 Y 111221112012 2220112120114 16 3 2 w eighted score w eighted score 0.8 11.6 0.6 2 0.5 1.2 1.8 1 1.62 0 0.81 0.81 0.36 0.81 0.8 0.72 1.6 0.8 0 1.6 0.64 0 0.64 10.53 11.18 5.14 Low er spoil embankmentsBackw aters – reconnections to IDB, field drains Y 0 Y 1210101112212 6 5.17 2 1120111111113 5 w eighted score 0 1 1.2 0.5 0 0.81 0 0.36 0.8 0.8 1.6 1.28 8.35 w eighted score 1.6 1 0.6 1 0 0.81 0.81 0.36 0.8 0.8 0.8 0.64 9.22 5.15 Channel Re-sectioning Y 1 1110102121112 7 5.18 Backw aters - new Y 1 1110101111110 10 w eighted score 0.8 1 0.6 0.5 0 0.81 0 0.72 0.8 1.6 0.8 0.64 w eighted score 0.8 1 0.6 0.5 0 0.81 0 0.36 0.8 0.8 0.8 0.64 7.11 5.19 Channel realignment N 0 w eighted score 0 00000000000 0 5.20 Changing primary and secondary channels (e.g. Ryburgh) N 0 w eighted score 0 00000000000 0 5.21 Low er embankments N 0 Weighted Score 0 00000000000 0 ‐2 ‐20‐2 ‐1 ‐2 ‐1 ‐2 ‐20 Weighted score G6: Alternative Options ‐1.6 ‐2 ‐1.2 ‐1 ‐1.8 ‐1.62 0 ‐0.72 ‐0.8 ‐1.6 ‐0.8 ‐1.28 ‐14.42 6.3 Mill Structures - reinstatement6.1 & maintenance Increase + Main hydropow river maintenance: er Yraw score Y ‐2 ‐2 ‐2 ‐2 ‐2 ‐2 ‐1 ‐10‐2 0 ‐1 ‐1 ‐18 Total Score Weighted Score Weighted score 0 00000000000‐1.6 ‐2 ‐1.2 ‐1 ‐1.8 ‐1.62 ‐0.81 ‐0.36 0 ‐1.6 ‐0.8 0 ‐0.64 ‐13.43 6.2 Increase main river & IDB channel maintenance: raw20.8 score 21 Y 20.2‐2 23.5‐2 11.5‐2 20.1‐2 7.43 10.88 26.8 29.8 11.8 20.68 Key Score Description Mean: 8.56 2High Relevance SD: 3.4 1Low Relevance 0Neutral High imp: >11.96 ‐1Low Detriment Low imp: <5.15 ‐2High Detriment Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 70

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

Table 5.9 - Results of MCA for Reach 16 (Elmham Reach) River Wensum Multi Criteria Analysis River 51 Criteria Group Ecology [A] Project Delivery [B] TechnicalUnit: [C] Wensum Group weighting 1 0.9 0.8 Reach: 16 Elmham Human Technical Geomorphic Flood Risk Climate Total Total Rank order 1170m Individual weighting within group 0.8 1 0.6 0.5 1 0.9 0.9 0.4 1 1 1 0.8 Length: Option / Compliance Compliance Compliance Contribution Compliance ComplianceEnvironment: Agreement Feasibility form & [C.c] Change & Raw weighted measure with with with to overall with Strategy withArchaeology; with & function [C.b] sustainability Score score applicable to International National Regional/Local ecology [A.d] objectives Statutorylandscape; Non ‐statutorypracticality [C.d] (highest reach Designation Designation designation (Wildlife & Stakeholdersrecreation Stakeholders [C.a] possible (SAC) [A.a] (SSSI) [A.b] (BAP) [A.c] Fisheriesowners; & (EA; NE; BDC;[B.d] (anglers; score 24) River Formoccupiers) & NCC) [B.b] Process) [B.a][B.c] Individual w eighting factor = 0.8 1 0.6 0.5 0.9 0.81 0.81 0.36 0.8 0.8 0.8 0.64 Option No. Option / measure G1: Do Nothing: No maintenance or restoration: raw score Y ‐2 ‐1 ‐1 ‐2 ‐1 ‐2 ‐1‐2002 0 1110‐1 ‐1 1‐1 3 ‐11 Weighted scoreWeighted score 0000.5‐1.6 ‐1 ‐0.6 ‐1 ‐0.9 ‐1.8 ‐0.81‐1.62 0 0 0.36 0 0.8 1.6 0.8‐0.8 0‐0.8 0.64 ‐0.64 1.39 ‐8.26 G3: TargetedG2: DoMaintenance: Minimum: minimal Raw score restoration: raw score Y Y 00001 1 0 0 1 2 0 1211110 4 Weighted score 0 1 0 0 0.9 1.62 0 0.36 1.6 0.8 0.8 0.64 7.72 G4: Continue as present: raw score Y ‐2 ‐1 ‐1 ‐1 ‐2 ‐2 ‐102‐1 ‐1 ‐1 ‐11 Weighted score ‐1.6 ‐1 ‐0.6 ‐0.5 ‐1.8 ‐1.62 ‐0.81 0 1.6 ‐0.8 ‐0.8 ‐0.64 ‐8.57 G5: River Restoration G5a M ill Structures: 5.1m Mill structures - improve operability + protocols: raw score N 0 w eighted score 0 0 0 0 0 0 0 00000 0 5.2m Mill structures - remove flow control mechanisms: raw score N 0 w eighted score 0 0 0 0 0 0 0 00000 0 5.3m Mill structures - low er mill sills levels N 0 Weighted Score 0 0 0 0 0 0 0 00000 0 Mill structures – bypass channels N 5.4m 0 Weighted Score Weighted Score 0 0 00 0 0 0 0 0 0 0 0 00000 0 0 000000 0 G5b Gravel works: 5.5m Fish passes N 0 5.7g Gravel glides Y Weighted Score 2 211221112010 0 0 0 0 0 0 0000016 1H 0 w eighted score 5.6m Mill structures - remove all1.6 2 N 0.6 0.5 1.8 1.62 0.81 0.36 0.8 1.6 0 0.64 12.33 0 5.8g Gravel glides + transverse hurdles: raw score Y 1 1 1 1 1 1 0 011019 w eighted score 0.8 1 0.6 0.5 0.9 0.81 0 0 0.8 0.8 0 0.64 6.85 5.9g Bed raising (large scale) Y 2 21120‐11‐11‐118 Weighted Score 1.6 2 0.6 0.5 1.8 0 ‐0.81 0.36 ‐0.8 0.8 ‐0.8 0.64 5.89 G5c Other: 5.10 Fencing: Raw Score Y 0 01011‐1 0210 05 10L Weighted Score 0 0 0.6 0 0.9 0.81 ‐0.81 0 1.6 0.8 0 0 3.9 5.11 Tree planting on top of bank: raw score Y 0 01211‐1 1210 19 8 Weighted score 0 0 0.6 1 0.9 0.81 ‐0.81 0.36 1.6 0.8 0 0.64 5.9 5.12 Tree thinning: raw score Y 0 001110020005 11L w eighted score 0 0 0 0.5 0.9 0.81 0 0 1.6 0 0 0 3.81 5.13 Deflector (using LWD and filled in w ith brush mattress) Y 1 2020111120112 2H w eighted score 0.8 2 0 1 0 0.81 0.81 0.36 0.8 1.6 0 0.64 8.82 5.14 Low er spoil embankments Y 0 11121‐1 1111 110 5 Backw aters – reconnections to IDB, field drains N w eighted score 0 1 0.6 0.5 1.8 0.81 ‐0.81 0.36 0.8 0.8 0.8 0.64 0 7.3 5.15 Channelw eighted Re-sectioning score Y 10 10 10 10 0 10 0 10111000009 0 7 5.18w Backw eighted aters score - new Y 0.81 111201011101 0.6 0.5 0 0.81 0 0.36 0 0.8 0.8 0.64 10 6.31 6 5.16 Bermw eighted creation score Y 0.81 121201110201 0.6 1 0 0.81 0 0.36 0.8 0.8 0 0.64 12 6.81 3H 5.19 Channelw eighted realignment score N 0.8 2 0.6 1 0 0.81 0.81 0.36 0 1.6 0 0.64 0 8.62 5.17 w eighted score 0 0 0 0 0 0 0 00000 0 5.20 Changing primary and secondary channels (e.g. Ryburgh) Y 1 11102‐2 1110 18 9L w eighted score 0.8 1 0.6 0.5 0 1.62 ‐1.62 0.36 0.8 0.8 0 0.64 5.5 5.21 Low er embankments N 0 Weighted Score 0 00000000000 0

G6: Alternative Options ‐1 ‐2 ‐1 ‐2 ‐18 Weighted score 6.1 Increase Main river maintenance: raw score Y ‐2 ‐2 ‐1 ‐2 ‐1.6‐2 ‐2‐2 ‐0.6‐1 ‐‐110‐1.8 ‐2‐0.81‐1 0 ‐1 ‐0.72 ‐17 ‐0.8 ‐1.6 ‐0.8 ‐1.28 ‐13.01 6.3 Mill Structures - reinstatement & maintenance + hydropow er Y Weighted score ‐1.6 ‐2 ‐0.6 ‐1 ‐1.8 ‐1.62 ‐0.81 ‐0.36 0 ‐1.6 ‐0.8 ‐0.64 ‐12.83 0 Weighted Score Total Score6.2 Increase main river & IDB channel maintenance: raw score Y ‐2 ‐2 ‐1 ‐2 0‐2 0‐10 0 0‐2 0 0 0 00000 0 5.6 17 10.6 15.5 5.8 14.67 ‐9.05 10.88 28.6 19 ‐2.6 12.48 Key Score Description Mean: 8.16 2High Relevance SD: 2.42 1Low Relevance 0Neutral High imp: >10.58 ‐1Low Detriment Low imp: <5.74 ‐2High Detriment Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 71

River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

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5.3.1 Results of the MCA options appraisal The MCA is not just about which options improve ecology. As discussed, implicit in the MCA is the assessment of options and measures against other issues such as flood risk, the human environment, construction feasibility and agreement with landowners and stakeholders. Assessing these issues alongside ecological factors allows the options and measures to be assessed realistically, and to identify where other issues may conflict with the objective of achieving ‘unfavourable recovering’ or ‘favourable’ ecological condition for the SSSI, and good ecological potential for the Wensum under the Water Framework Directive. It should be noted that information from the environmental baseline and stakeholder consultation specific to each reach was applied to the MCA for that reach. The results from the MCA do differ for each of the reaches in Unit 51 but have a number of similarities including:  The options of ‘Do nothing’, ‘Continue as present’ and ‘Alternative options’ all produced negative scores, with the exception of Reach 14 where the ‘Do Nothing’ option produces a low positive score.  The option of ‘Do Minimum’ produces positive scores for all three reaches.  The options of ‘Targeted maintenance’ and ‘River restoration’ all produced positive scores. A negative score indicates that the option is detrimental to the project’s objectives of achieving ‘unfavourable recovering’ or ‘favourable’ condition status for the River Wensum. This suggests that ‘Do nothing’ (i.e. abandoning the river) is generally not an option and work is required to achieve the objective. This is surprising as a popular notion within the river restoration community is that sometimes allowing the river ‘to sort itself out’ can be viewed as the best option, particularly if maintenance is considered to be harming the river condition rather than improving it. In the case of Unit 51, the overall impact of the Swanton Morley Mill structures and Elsing Mill on the form, function and ecology of the impounded upstream reaches is highly significant. The ‘Do nothing’ option will not change this impact and action is required to address the impoundment prior to the implementation of any in-stream restoration measures within river sections currently affected by backwater impacts on flow and stream function. The option of ‘Continue as present’ is considered detrimental to the project although ‘Do minimum’ scores positively as some restoration, especially in Reach 14, will provide beneficial effects. The ‘Alternative options’ also received negative scores and this is largely a consequence of the scores attributed to the ‘Ecology’ criteria. This applies to hydropower options, which involve the generation of energy through harnessing the kinetic energy of water. Hydropower is seemingly attractive, as it is a form of renewable and ‘clean’ energy with added benefits such as reusing historic structures along watercourses. Hydropower is being implemented elsewhere and the Environment Agency has produced a position statement (2009a) and guidance (2009b) on how such projects should be developed, assessed and implemented. Similarly, Natural England has also developed a position on hydropower which is available on their website. When assessed against both the MCA and Environment Agency and Natural England guidance, the implementation of hydropower schemes for the River Wensum has been found to score negatively. Impacts on geomorphology, hydraulics, flow regimes and biological connectivity may have an adverse effect on flora and fauna (e.g. fish). Thus, whilst providing some benefits, hydropower ultimately runs counter to the high-level project objectives for geomorphological and ecological enhancement. Any likely wider benefits of renewable energy are negated by the potential for adverse local effects on other natural resources and receptors. Options and measures with negative scores will not be progressed as part of the River Wensum Restoration Project as they will not improve the ecological or geomorphological condition of the river.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

The MCA has demonstrated that the options of ‘River restoration’ and ‘Targeted maintenance’ will help Unit 51 to achieve ‘unfavourable recovering’ or ‘favourable’ ecological condition. The ‘River restoration’ option has a number of associated measures with different scores. All of these scores are positive, indicating they should be included as part of the preferred restoration design. Additionally, each reach has a different score for each measure due to the results of the MCA reflecting the baseline condition of the reach. The top scoring measures for each reach are given in Table 5.10. Table 5.10 - Summary of favourable options and measures for Unit 51

Term Reach 14 Reach 15 Reach16 River Restoration River Restoration River Restoration Favourable options Targeted Targeted Targeted maintenance maintenance maintenance Berm creation Gravel glides Gravel glides Channel realignment Berm creation Deflectors Top 5 Deflectors Deflectors Berm creation River Restoration Backwaters - Mill structures – Lower spoil Measures reconnections bypass channels embankments Mill structures – Backwaters - Backwaters - new bypass channels reconnections

The value of the weighted scores provides an indication of the relative importance of the measures in achieving ‘unfavourable recovering’ or ‘favourable’ ecological condition for the reach and suggests the order in which measures could be applied. This provides a useful indicator for identifying which opportunities to look for first in a reach. For example, in Reach 14 the highest scoring measure is berm creation, so this is the first opportunity looked for in the reach, followed by the second highest measure, channel realignment and so on. All of the measures are valid so it is not recommended that a cut-off be imposed at a certain value. However, the positively scoring measures have been grouped into bands of importance to give an indication of their relative importance in restoring the reach to favourable condition (see section 6 for further details). The frequency, location and manner in which measures are applied require professional judgement, informed by in-depth understanding of the baseline conditions of the reach. It is important to highlight that cost has not been included in the MCA as it is imperative that options and measures that move the reach towards achieving ‘unfavourable recovering’ or ‘favourable’ ecological condition are identified regardless of cost. Whilst cost is an important factor, it should not preclude an option or measure being identified and implemented. Instead, costs should be considered in terms of how options are implemented, and used to identify savings by using local material, phasing work appropriately or using different techniques (e.g. a LWD deflector compared with a rock deflector) to achieve the same result at a lower cost. The MCA provides a powerful tool for appraising all options and associated measures in a consistent, replicable and transparent way. It should be noted that the MCA should be viewed as a filtering tool to allow favourable options to be identified and unfavourable options to be dropped. How those favourable options and measures are applied to a reach is a case of professional judgement, and this is discussed in Chapter 6.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

6. Developing Conceptual Design 6.1 Introduction and approach This chapter explains how the recommended options of ‘River restoration’ and ‘Targeted maintenance’ can be applied to each reach. To set this in context, the chapter initially details:  The project in the context of river restoration (Section 6.2.1).  How ecology has been integrated into the conceptual design process (6.2.2).  How ‘Targeted maintenance’ is included within the recommended option (Section 6.2.3). Reach objectives, their review, and preferred restoration measures for Reach 14, Reach 15 and Reach 16 are outlined in Sections 6.3 to 6.5.

6.2 Description of River Restoration and Targeted Maintenance options

6.2.1 River restoration theory The term river restoration can be used to describe a number of different activities that require different levels or magnitudes of change. River alteration projects form a continuum from ‘full restoration’ through to ‘erosion control’ (Plate 45). The range reflects the varying level of human intervention in natural systems to manage risk (Gillian et al., 2005).

Plate 45 – River alteration continuum This distinction between levels of work and sustainability was developed further in the geomorphological appraisal of the River Wensum, where Sear et al. (2006) categorised the geomorphology of reaches on the River Wensum into six management classes of river restoration (Table 6.1). This provides a method of quantifying the magnitude of restoration needed on a reach by reach basis depending on the baseline conditions and opportunity for change.

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River Wensum Restoration Strategy Implementation SSSI Unit 51: Feasibility and Environmental Scoping Report

Table 6.1 - Different management classes of restoration activity

Term Definition Restoration of channel processes and forms to pre-disturbance Restoration conditions. Physical modification to the river form to re-create physical habitats Rehabilitation (e.g. re-meandering, riffle installation, bed level raising). Addition of structural features to improve physical habitat diversity Enhancement (e.g. narrowing, woody debris). Afford legal protection to the site and monitor for change in status. Protect & monitor Given that the site has legal protection (SSSI / SAC), monitor to ensure that the status is maintained and take action if required. Amplification of existing processes to encourage recreation of physical Assisted natural habitats (e.g. encouraging berm formation to narrow channel, removal recovery of bank revetment to create sediment supply). Protect site against further degradation not necessarily with legal Conserve statute.

Sear et al. (2006) developed this further by categorising river restoration techniques into active and passive restoration based on the restoration approach of form mimicry or process based restoration (Table 6.2). This presents a range of typical river restoration measures that can be followed and all of these were included in the MCA analysis as all are applicable to the Wensum to varying degrees. Table 6.2 - Active and passive river restoration measures

Active Restoration – Passive Restoration – (physical (physical creation of forms manipulation of flow and or removal of structures to sediment transport regime to improve degraded create physical habitat and to ecosystems.) improve degraded ecosystems.) Form-mimicry – The re-creation of physical Gravel augmentation which then Riffle recreation. habitat features without is moulded by river flows into bed Re-meandering. reference to the processes features (riffles). required to create them. Process-based restoration Mill weir removal – restores Reduction in catchment sediment The use of physical sediment connectivity and supply. processes to restore hydraulic gradient. Management of flow regime (flow degraded physical habitats to Re-occupation of an old re-naturalisation). a more natural form. channel course.

All three reaches in Unit 51 have been categorised into the ‘Rehabilitation’ Management class (see Table 6.1) (Sear et al., 2006; JBA, 2007). This is defined as: “Physical modification of the channel to re-create self sustaining physical habitats (e.g. riffles, side berms), generally where the channel is currently substantially over deep and / or over wide’’.

Therefore ‘Rehabilitation’ does not mean that the aim of the ‘River restoration’ option is to:  Return the river and floodplain to pre disturbance conditions;  Return the river to its high maintenance regime of wholesale dredging of the river channel; or  Return the functionality of the mill systems.

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The emphasis for Unit 51 is on changing present river form and flow processes to help the river develop conditions more typical of its chalk river type. This does not mean that this is undertaken in isolation to the wider issues and constraints of the catchment (e.g. flood risk to people and property). Rather, improving the river condition should aim to provide multiple benefits in terms of reducing flood risk, reducing the need for regular extensive maintenance by creating a self-sustaining system, creating managed ‘hotspots’ for ‘Targeted maintenance’, improving amenity value and improving habitat condition and diversity for a variety of flora and fauna. To do this, different restoration measures can be used to varying degrees. The density and type of river restoration measures can be applied in three ways to provide the following design philosophies:  Total Restoration Design Philosophy (High-density application of fully formed restoration features) – This approach provides ‘complete’ river restoration and is applicable when the river does not have the capacity to form features itself.  ‘Kick Start’ Restoration Design Philosophy (Medium-density application of partially formed features) – This approach uses the existing form and function of the river and provides in channel and out of channel features to allow the river to kick start natural geomorphological process by building upon the features provided.  Opportunistic Restoration Design Philosophy (Low-density application of fully formed features) – This approach is indicative of opportunistic river restoration design where restoration measures are applied to a short length of river due to favourable circumstances. This often provides improvement to the river condition locally but can have limited benefit for the river condition on a SSSI unit basis. River restoration that has been undertaken on the River Wensum in the past has been undertaken within the Opportunistic Restoration Design Philosophy. The RWRS has provided the opportunity to change this philosophy by providing a whole river vision and mechanism to achieve river restoration on a catchment scale. To achieve the vision of the RWRS, it is recommended that the ‘Kick Start’ Restoration Design Philosophy is applied for the following reasons:  The river is slowly recovering naturally from legacy maintenance practices, demonstrating the capacity to develop morphology features and ‘self heal’.  Whilst not ideal or recommended, modifications to mill operating regimes are likely to be undertaken at different timescales to river restoration. Consequently, implementing total restoration while mill structures are unchanged represents a future risk to the design if water levels change significantly.  It provides value for money by not installing features that the river can form naturally over time.  It allows a phased approach to be adopted by allowing the river time to adapt to river restoration measures before determining if additional measures are required. Therefore, the approach of ‘Kick Start’ Restoration Design Philosophy, within the context of the ‘Rehabilitation’ management class for the River Wensum, is to deliver the minimal amount of physical works in the river that will achieve sufficient change in hydromorphological form and fluvial processes to accelerate the river’s natural ability to ‘self-heal’. More specifically the design philosophy is to: 1. Restore the river to a form and function characteristic of a Norfolk chalk river.

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2. Put forward recommendations that will see restoration measures implemented in 2010 to help restore ‘unfavourable recovering’ or ‘favourable’ ecological condition to the SSSI habitat features.

3. Provide a ‘kick-start’ by only undertaking works to create features that the river would not be able to do itself.

4. Provide an increase in the patchiness and diversity of features that are sufficient to allow an improvement in natural processes and which will increase both the rate, and amount of self- restoration at any point along the unit.

5. Provide sufficient strength of processes that will allow significant self-restoration by 2015 to meet WFD timeframes.

6. Place measures at an appropriate frequency of 20m to match present day flow rates and erosion / deposition patterns. However, they must also respect the larger channel form features such as the relic bend length of 35m derived from ancient river flow rates. This will ensure there is sustainability over any likely range of flow rates, and their associated erosion / deposition patterns.

7. Ensure that the channel forms provide durable results against the varying flows and water levels generated by long-term climate change impacts, and in-channel vegetation growth in the short-term.

In respect to point 1 above, it is recognised that the River Wensum, and other Norfolk chalk rivers, are slightly different from ‘classic’ chalk rivers. This is explored in detail in 3.2.1 and the Geomorphological Appraisal of the River Wensum by Sear et al. (2006) and also summarised in the JBA report (2007). 6.2.2 Designing for ecology The restoration strategy applied to each reach must provide a measurable ecological benefit at both a species and community scale in order for the River Wensum to achieve ‘favourable’ ecological condition. Ecological monitoring of river restoration sites will be one of the key ways of assessing the success of implementing the strategy. Equally, prior to the implementation of specific river restoration measures, consideration must be given to the potential for harm to be caused to existing ecological features through direct damage, loss of habitat, or alteration to existing river form and function. The permanency of any effect, adverse or beneficial, will need to be assessed as well as the potential for natural recovery within the system. This process has required an extensive ecological baseline review of the distribution and status of ecological features in the River Wensum, as discussed in Section 3. This has been coupled with the identification of physical habitat constraints and catchment scale pressures that are influencing condition status. Furthermore, a detailed review of the SSSI / SAC interest features has been undertaken to promote appropriate restoration measures for these key species and community assemblages. It is important to note that at this stage the review has concentrated on designated ecological features only, although the intention is to add additional ecological features, following consultation with statutory stakeholders. The following information has been collated for each of the key ecological features through extensive literature and data review:  Protected status and UK distribution.

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 General ecology e.g. life cycle, feeding requirements.  Specific habitat requirements for all life stages, including: - Substrate - Water quality - Water quantity, and  Factors known to currently affect species / community distribution and populations. For each of the Strategy wide restoration measures (e.g. tree thinning, gravel glide placement), both the positive and negative effects of implementation has been determined through an initial identification of the habitat requirements for each species and community. Following this, an assessment was made of how the habitat may alter following implementation of a river restoration measure and the resultant impact, adverse or beneficial, that this could have on species distribution and community persistence. The recommended restoration measures that were identified using the MCA are displayed in Table 6.3 along with the associated potential ecological benefits to different species and communities. These benefits will arise by ensuring that the adopted restoration measures are integrated (e.g. berms are installed to promote favourable flow over the top of installed gravel glides). Integrated measures to maintain appropriate geomorphic form and function and maximum ecological benefit will ensure resilience and persistence of the ecological communities that develop. Further details of how the measures benefit the designated species and communities can be found in Appendix C. Table 6.3 - River restoration measures and their potential ecological benefits

Restoration Measure Description & Potential Ecological Benefits Fencing constructed landward of the river bank to prevent bank erosion from the impacts of cattle grazing, with a consequent reduction in sediment ingress. Protects marginal habitat and Fencing promotes growth of emergent and marginal / aquatic plants, with associated improvement for aquatic macroinvertebrate fauna (Desmoulin's whorl snail -Vertigo moulinsiana). Tree planting to cast shade over the water to control excessive macrophyte growth, provide cover for fish and to develop erosion Tree planting resistance from root reinforcement. Also provides input of leaf litter and LWD of value to macroinvertebrate fauna including white-clawed crayfish. Selective felling or lopping to provide light onto the water to encourage marginal and submerged macrophyte development and Tree thinning associated macroinvertebrates. In addition, this will generate appropriate materials for use in restoration measures, e.g. brush-fill and deflectors. Downstream pointing LWD placed and secured at the upstream side of the deflector to create flow diversity; in-filled downstream with Deflectors brush to promote silt deposition and marginal plant growth. Provides (using LWD and filled in refuge for fish fry behind structure and good flow diversity for with brush mattress) macroinvertebrates and submerged macrophytes (e.g. Ranunculion fluitantis and Callitricho-Batrachion vegetation). Removal of dredging-based informal embankments to allow out-of- bank flow across the floodplain, and back into the river. Ensures fish Lower spoil embankments that are washed out of the channel during flood can return to the river as the floodwaters recede. May also improve adjacent wetland systems through water level regime. Berm creation Horizontal lowering of bank top up to half the channel width to Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 79

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Restoration Measure Description & Potential Ecological Benefits increase flood flow capacity and generate arisings for bed raising where no embankments exist. Creates marginal shelf habitat for macrophytes and associated fauna plus refuges from high flows for fish fry. Improvement to in-stream flow conditions. Utilizing existing wet features by connecting them to the river to create essential refuge habitat for fish and other fauna. This Backchannels – measure is implemented to aid the natural recruitment of fish stocks. reconnections to IDB and existing field drains Achieved through provision of nursery habitat and refuge from high- flow events. Additional utilisation by a variety of aquatic biota, e.g. brook lamprey ammocoetes. Creating habitat where no other water bodies exist e.g. dog-leg with downstream end open and upstream end fed by percolation. This Backchannels – create measure provides refuge for fish and a place for fry to rest during new features floods, so limiting the loss of fry to reaches downstream of mill structures. Benefits all fish species through increasing recruitment potential. Creation of short lengths of full raised bed, dressed in gravel to create variation in flow and habitat for various macroinvertebrates Gravel glides and macrophytes in addition to provision of spawning substrate for fish species, e.g. trout, barbel and brook lamprey. Creation of long lengths of full width raised bed, dressed in gravel, to Bed raising reconnect channel with floodplain and create variation in flow and habitat for various fish species, macroinvertebrates and macrophytes. Full depth excavation from bank top to increase lateral variation in Channel realignment to planform, either one bank or both, using arisings to infill opposite increase river sinuosity bank. Improved geomorphological form and function beneficial to a range of associated biota.

Each of these measures has a different effect dependant on the flows in the river. Table 6.4 summarises the relationship between flow height and impact.

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Table 6.4 - The effect of river restoration measures according to flow condition

River Flow / Level Mill Structures Gravel Glides Deflectors New Backchannels Reconnection Backchannel Creation Berm Realignment Channel Re-sectioning Channel of Embankment Removal of Spoil Removal Tree Thinning Tree Planting Fencing Over bank I I D D D D D

Bank full D I I I D I D D D I

High flow D I I D D D D D I

Low flow D D D D I D D I Key: I=Indirect; D=Direct The effects can be direct (D), such as deflectors which will physically push flow across the river at low flows. Higher flows will go over the top of the deflector and therefore there will be no direct effects. However, the impact at low flow will have changed local silt deposition and hence vegetation patterns. The combined effect of the deflector and the vegetation will have an impact on the higher flows, but this depends on several factors such as plant growth; this effect is described as indirect (I). The combination of each of the different measures ensures that process and form of the river is impacted under all flows and so will increase the rate of change towards self-healing. From an ecological view it means that conditions within the channel vary so that biota can move to similar conditions, but in a different location, as flow increases. 6.2.3 Targeted maintenance The ‘Targeted maintenance’ option recognises that there is a need for some maintenance to be undertaken on the River Wensum due to the various pressures that limit the potential for the channel to be a totally self-cleansing and regulating system. It is also an option that can be undertaken while river restoration measures are being designed and implemented. A separate targeted maintenance protocol is being developed which sets out in more detail where, how, when and by whom maintenance will be undertaken. The protocol will allude where possible to policies such as those contained in the Broadland Rivers Catchment Flood Management Plan, specifically the reduction in maintenance of fluvial systems. In addition, the protocol will draw upon consultation with internal Environment Agency functions and other stakeholders and will have regard to current maintenance practices. The measures that are included within the ‘Targeted maintenance’ option are outlined in Sections 6.2.4 to 6.2.7. 6.2.4 Silt removal at identified ‘hotspots’ These are sections of the river where silt accumulation will have an operational impact in terms of flood risk management. Maps indicating the distribution of ‘hot spots’ on the River Wensum were received from the Water Management Alliance on behalf of the Norfolk Rivers IDB. Typically these are sections of channel upstream of mill structures where silt deposits interfere with the flow of water approaching the structure, and limit the structure’s capacity, so increasing local flood risk. Generally it is recommended that a 200m length of channel upstream of each mill is targeted for Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 81

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de-silting. This will also allow the character of the mill leat to remain. Without the implementation of river restoration and lowering of levels at mills, de-silted sections of river will tend to accumulate fresh deposits of silt. The de-silting operation is therefore not sustainable in the long term. It is worth noting too, that Norfolk chalk rivers have a higher sand content in the river substrate than a typical chalk river, in downstream sections, as a result of ingress of material from the drift. Restoration and targeted maintenance will not seek to remove these features and will work with them. 6.2.5 Clearance of main channel immediately downstream of identified IDB drain outfalls This is to allow the IDB drains to discharge freely, otherwise their ability to flow freely is compromised, which in turn increases siltation, and so increases the need for maintenance in areas which are often valuable as nursery habitat for fish. The inability to discharge also increases flood risk from the drain, which in some instances will significantly impact on property flooding. It is recommended that 100m downstream of confluences are regularly inspected and cleared of silt and excessive marginal vegetation if necessary. 6.2.6 Clearance or realignment of fallen trees blocking the channel Clearance of fallen trees only needs to occur if they are within the impounded section immediately upstream of the mills, or the 100m stretch downstream of IDB drain confluences, or are impacting directly on flood risk to houses, such as river blockages at bridges. Otherwise, the trees should be realigned to provide flow diversity, and LWD. Trees may present a problem on impounded river reaches, as they may assist a breach in a river bank where the river is a high level carrier. This is undesirable, in that the objective of the strategy is to manage change, rather than to allow unchecked natural change. 6.2.7 Strategic weed cutting This should only be carried out where there is a direct flood threat to houses caused by elevated water levels, or where freeboard is unlikely to be sufficient to receive likely rainfall. It is likely to be required in the 200m mill leat and 100m IDB drain confluence sections. As these are discrete sections, where access is reasonable, the use of weed cutting bucket equipped excavators can be used, without the need for weed boats to travel substantial lengths of the river. This removes the need for tree management to allow passage of a weedboat, or to allow cut weed to float downstream to a designated pull-out point.

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6.3 Reach 14: Elsing Reach This section defines the preferred restoration of Reach 14 by describing key existing features; reviewing the recommended measures as stated in the RWRS; presenting the results of the MCA scoring and detailing rehabilitation measures applied to the reach. In defining the preferred restoration of Reach 14 it has been considered appropriate that the reach be divided into 3 sub-reaches to reflect the differing geomorphological character present along its 4.83km length. Field observations made in January 2011 identified this reach as longitudinally lending itself to different restoration measures and as presenting different opportunities / constraints. The 3 sub-reaches run sequentially from Swanton Morley Mill structures to Elsing Mill and their extent and general character is described in Table 6.5 and shown in Figure 6.1. A conceptual restoration plan (Figures 6.2 to 6.4) and indicative cost estimate is provided for each of the 3 sub-reaches. Table 6.5 – Key characteristics of Reach 14 sub-reaches

Sub-reach Sub-reach Name Extent Character Code (km) Downstream of the Environment Agency flow gauges this sub-reach is free flowing Swanton Morley with good gradient and in places gravel Reach 14a Mill structures to 0.88 dominated bed substrate. The overall Hillhouse Farm planform is straightened with spoil embankments occurring along both banks. Sub-reach has gross meandering planform although channel is over-widened and over- deepened throughout. River is perched Hillhouse Farm to Reach 14b 2.82 above the surrounding floodplain which is Penny Spot Beck characterised by extensive field drainage network including discharge from Penny Spot Beck. Impounded sub-reach with significantly Penny Spot Beck to over-widened and over deepened channel. Reach 14c 1.13 Elsing Mill Very limited habitat diversity occurs in this sub-reach.

6.3.1 Key existing features influencing proposed restoration measures Table 6.6 presents a brief description of the existing conditions of the reach as observed during the site visit conducted on 13th and 14th January 2011. The purpose of the visit was to consider the reach objectives on the ground.

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Table 6.6 - Significant features and possible measures observed for Reach 14 during site visit (January, 2010)

Noted Feature Possible Measure Features common to all sub-reaches River embanked throughout and in places perched above and disconnected from the Selectively lower embankments to encourage floodplain. Embankments appear to be flood flows to TLHB floodplain. composed of river dredgings (Plate 12). Utilise existing field drainage network - connect Limited off-channel riverine habitat to river to provide backwater habitat and refuge throughout. areas for fish. Selectively improve connectivity of main river IDB drain and wider drainage network has its habitat with these systems which may act as own intrinsic ecological value with patchy colonisation sources. However, this will need to chalk stream vegetation plant communities consider the potential spread of undesirable noted during the site visit in January 2011. species and water quality impacts. Acts as a receiving channel for out of bank flows near to mill which cannot return to the river due IDB drain to TLHB discharges to the river to the embankments: removal of these some 3.4 km downstream of Elsing Mill embankments would reduce surcharging of the (Plate 13). IDB drain as water can drain directly back to the river. Sub-reach 14a: Swanton Morley Mill structures to Hillhouse Farm Good gradient and free flowing conditions Create in-channel improvements through present within this sub-reach. installation of berms and additional gravel. Reinstate flow through loop to improve habitat Old meander loop present in downstream and flow diversity, combine with reconnection to section of sub-reach (Plate 10). existing drainage network. Integrate measures to improve river condition Sub-reach is affected by the backwater with works required to reinstate free flowing river created by Elsing Mill. conditions at mill location. Augment with additional gravels and combine with berm installation to create appropriate Gravel bed present in free flowing sections. spawning habitat and conditions for target chalk stream communities. Reconnect drainage networks through terrestrial Presence of extensive field drain network on SSSI land parcels to create backwater habitat in TRHB floodplain. Includes SSSI land parcel this reach. Works must not compromise units 34 and 35 and part of 36. terrestrial SSSI unit conservation objectives. Sub-reach 14b: Hillhouse Farm to Penny Spot Beck Presence of extensive field drain network Reconnect drainage networks through terrestrial and spring fed stream in hydrological SSSI land parcels to create backwater habitat in connectivity with the river on TRHB this reach. Works must not compromise floodplain upstream of Castle Farm. terrestrial SSSI unit conservation objectives. Includes part SSSI land parcel Unit 36. Maintain free discharge at confluence. This Confluence of the Penny Spot Beck in the could potentially be achieved through the use of downstream section of sub-reach (Plate 15). deflectors to modify flow patterns at confluence. Norman Motte & Bailey Castle located at Floodplain narrow at Castle Farm (250m narrowest point of valley, and probable ancient wide) compared to a more typical width of crossing point. Natural feature which informs 500m. consideration of landscape in proposals.

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Noted Feature Possible Measure Generate large woody debris through selective felling in these areas and use material in the construction of berms and / or deflectors. Plant There are few specimen trees along the semi-continuous stands of native wetland trees, banks of the main river. The majority occur e.g. alders, along main river channel to create a in this sub-reach (Plate 16). mosaic of shade conditions and improve riparian habitat. Fencing to encourage marginal plant development and remove effects of poaching. Sub-reach 14c: Penny Spot Beck to Elsing Mill Create additional mill bypass channel through realignment works to reinstate free flowing river and reduce backwater effects. Within the Sub-reach is significantly affected by the realigned section install gravel glides and create backwater created by the flow control asymmetric channel form to create a diversity of structures at Elsing Mill (Plate 21). habitat and flow conditions. Install in-stream habitat improvement measures e.g. berms / gravel glides in free flow sections (currently only in upper section of reach). Channel heavily modified, over wide and over deep on approach to Elsing Mill. Large Improve in-channel flow and habitat diversity meander wavelength planform present (Plate through installation of berms and deflectors. 17). Encourage change to primary flow route though Old meander loop present in middle section use of in-stream features such as berms and of sub-reach (Plate 18). deflectors and potentially combine with realignment works required to bypass Elsing Mill.

6.3.2 Review of Reach 14 Strategy Objectives Appendix A to the RWRS (JBA, 2007) details a ‘Reach Restoration Strategy’ for each reach. These objectives have been the starting point for the consideration of rehabilitation activities within each reach. A review of these objectives is presented below in Table 6.7. Table 6.7 - Review of strategy objectives and recommendations for Reach 14

RWRS Objectives Atkins Comments on the RWRS Partially agree: Effects of impoundment All works must integrate with lowering of created by Elsing Mill can be more 1.1 structures at Elsing and Swanton Morley effectively managed through creation of Mills and associated river works. additional mill bypass channel. Disagree: Although silt accumulations De-silt channel just upstream of occur upstream of the structures, these tend 1.1 Swanton Morley structures. to be restricted to marginal areas and hard bed conditions persist across the channel. Agree: Physical channel narrowing measures are required to address over widening throughout the entire reach, especially on approach to Elsing Mill. Gravel augmentation will provide additional Physically narrow and augment bed with 1.2 benefits but only in sections of good gravels. gradient, and following removal of the backwater effect from Elsing Mill. Gravel augmentation and narrowing is considered to be suitable in sub-reach 14a where free flowing conditions exist despite the Elsing

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RWRS Objectives Atkins Comments on the RWRS Mill backwater. Partially agree: Reinstating natural floodplain process is a desirable option. The IDB channel to the TLHB has particularly notable flora due to intercepting Remove embankments to reconnect the ground water; and the introduction of 1.3 river to its floodplain. nutrient rich river water may compromise this. Embankment lowering therefore needs to consider pathways of water flow across the floodplain and implications on wider ecology. Partially agree: Encouraging development of marginal and bankside vegetation through landscaping works will promote natural narrowing and improve habitat Encourage development of marginal / 1.4 diversity. Due to the reach being bankside vegetation. significantly over wide and over deep it is unlikely that this measure alone will create the degree of narrowing required to improve in-stream flow character. In the 100 to 200m downstream of Swanton Morley Mill structure and in the Agree: Reach immediately downstream of immediate scour pool area of good mill is likely to provide good fisheries habitat 2.1 habitat value, no works are required and on account of scour pool and well this area should be conserved and oxygenated water. allowed to re-vegetate naturally. Disagree: Water level control can be achieved by bypassing the mill. Bed conditions near to the mill are good with little if any siltation. There is existing natural Initial work required is for bed and bank berm development which would provide stabilisation associated with lowering of 2.1 bank stabilisation when combined with a Elsing Mill structures at downstream progressive reduction in water levels. The end of reach. channel is so wide that any bed mobilisation is extremely unlikely. There is potential for loss of amenity / aesthetics upstream of the mill as a result of partial flow diversion. Partially Agree: Silt deposits do need Appropriate measures required to monitoring, but with lower water levels, and 2.2 manage silt deposits upstream of the increased marginal vegetation, silt deposits mill. will be self managing. Disagree: The channel is so over wide, as Augment bed on average by 1.2m using well as over deep, that the amount of gravel local gravels wherever possible and required to create changes in flow in the 2.3 create up to 66 gravel glides or riffles in reach is prohibitive, and unlikely to provide the reach. sufficient habitat improvement to warrant the change. The channel is on average 10.1m over wide and physical narrowing (with Partly Agree: There needs to be works to associated landscaping and fencing) 2.4 the channel irrespective of any works to the may have to be considered to restore mill. the full function of the channel in this reach following works at the mill. Adopt / maintain maintenance regime Agree: With the depth and width of the and riparian management to allow channel creating homogenous and sluggish 2.5 channel to create natural variations in flow the river struggles to develop new local channel width and habitat niches. features such as berms. Maintenance and

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RWRS Objectives Atkins Comments on the RWRS management therefore need to help the natural processes achieve sustainable change. Post-project monitoring is required, Agree: Any of the works require pre and 2.6 especially in association with works at post change monitoring to ensure outcomes the mill structure. are as expected. Summary Reach 14: Atkins agrees or partially agrees with the majority of the principles established by JBA for this reach. Disagreements relate to works required at Elsing Mill and Swanton Morley Mill structures. A preferred option of flow diversion through the existing drainage network to provide free flowing conditions and mill bypass is presented as an alternative to structural changes at Elsing Mill.

6.3.3 Reach 14: Recommended restoration This section provides the details of the options and measures proposed for this reach which have been derived from the Multi-Criteria Analysis (refer to Section 5.3). A summary of the MCA results in their rank order is provided in Table 6.8 and these are further divided into importance according to how far the measure will move the reach towards achieving ‘unfavourable recovering’ or ‘favourable’ ecological condition. In addition, the suitability of each of the positive scoring measures identified by MCA for Reach 14 is presented at a sub-reach scale. The suitability of each measure has been determined by reference to existing channel and floodplain form resulting in the assignment of a rating (High, Medium, Low) for each measure at a sub-reach level (Table 6.9). This assessment is reflected in the conceptual restoration plans provided for each of the sub-reaches (Figures 6.2 to 6.4). Table 6.8 - Recommended restoration options for Reach 14 Option Description Weighted Score Highly Important Measures 5.16 Berm creation 12.03 5.19 Channel realignment 10.21 Important Measures 5.13 Deflectors 9.83 5.4m Mill structures – bypass channel 6.42 5.17 Backwaters - reconnections 9.05 G3 Targeted maintenance 8.98 5.12 Lower embankments 7.41 5.18 Backwaters – new 7.92 5.7g Gravel glides 7.03 5.11 Tree planting 6.22 5.12 Tree thinning 5.88 Less Important Measures 5.10 Fencing 4.95 5.20 Changing primary and secondary channels 4.33

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Table 6.9 – Restoration measure suitability rating for Reach 14 sub-reaches

Option Description Weighted Score Suitability Rating for Sub-reach for Reach 14a 14b 14c 5.16 Berm creation 12.03 High Medium Medium 5.19 Channel realignment 10.21 Low Low High 5.13 Deflectors 9.83 Medium Medium Medium 5.4m Mill structures – bypass channel 6.42 n/a n/a High 5.17 Backwaters - reconnections 9.05 High Medium Low G3 Targeted maintenance 8.98 Medium Low High 5.12 Lower embankments 7.41 Medium Low Medium 5.18 Backwaters – new 7.92 Low Medium Low 5.7g Gravel glides 7.03 High Low Medium 5.11 Tree planting 6.22 Medium Medium Medium 5.12 Tree thinning 5.88 Low Low n/a 5.10 Fencing 4.95 Low Low Low 5.20 Changing primary and secondary channels 4.33 Low n/a Low

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Reach 14 presents a number of technical challenges that need to be addressed if the condition assessment of the SSSI is to be improved. The river is significantly impounded at Elsing Mill in the downstream end of the reach, and this is combined with an over wide and over deep channel partially perched above its flood plain. Restoration measures implemented solely within the current channel would not deliver long term benefits unless these issues are addressed. The following restoration actions are considered to be the most effective in addressing the constraints to appropriate river form and function which are present in this reach:  Channel realignment in downstream section of reach to provide a bypass channel around Elsing Mill. - Creates longitudinal connectivity and allows fish movements to and from Reach 13 downstream without the need to adjust structures at Elsing Mill. - Reduces impoundment of the river behind Elsing Mill facilitating improvement in the flow conditions. - Creates additional habitat along the new channel which can be designed to incorporate gravel glides. - Provides additional flood storage through the portioning of flow.  Reconnections to existing field drains to improve availability of backwater/side channel habitat and potentially improve terrestrial SSSI condition in Units 34 and 36.  Use localised in-river features to improve habitat variability e.g. berm creation.  Selectively lower spoil embankments to improve floodplain connectivity and provide flood water storage.  Install gravel glides in free flowing upper section. 6.3.4 Targeted maintenance Following the principles established in section 6.2.2 the following measures are suggested and may form part of the targeted maintenance protocol being developed for this unit. These include: 1. Silt removal. This is recommended immediately upstream of structures, or where silt deposits will limit discharge at confluences with IDB drains or significant tributaries. The only structure on this reach is Elsing Mill. Monitoring and clearance of encroaching silt will be needed within 10m upstream and downstream of each structure at the mill. 2. Clearance of main channel downstream of confluence with IDB drains. There is one confluence with an IDB drain in this reach, namely Penny Spot Beck. At present there are no connections to off-channel backwaters that require inspection and clearance of encroaching marginal vegetation. 3. Clearance or realignment of fallen trees blocking channel. Clearance is only required where they are impacting directly on flood risk to property or the structural integrity of third party assets. Elsing Mill is the only significant structure in this reach, and therefore the same clearance distances as identified for de-silting apply here. 4. Strategic weed cutting. This is only needed where there is direct threat to houses caused by elevated water levels, or where freeboard is unlikely to be sufficient to receive likely rainfall. Channel conditions downstream of confluences can impact on this, so the sections identified for silt removal need to be inspected for consideration of in-channel weed cutting.

6.3.5 Restoration Measures A number of the restoration measures identified by the MCA have been incorporated into the preferred outline restoration design for Reach 14, which is shown in Figure 6.1. Of the restoration measures selected for this reach, the highly significant ones are:

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Berm creation This reach is significantly over wide and over deep compared to the natural cross-section of the river. The depth of water has limited any natural re-adjustment and hence the establishment of any self developing berms is limited. The addition of berms would aid this process and would improve in-channel habitat, particularly for coarse fish which presently have little cover. The berms would also help reduce the cross-section width, which in turn would improve silt and river weed management by increasing velocity in mid-channel, moving silt on and inhibiting still water plants from growing. Channel realignment Plates 17, 19 and 20 show that the main channel and Elsing Mill bypass structure both have sufficient capacity for typical winter flows, whereas the existing bypass channel does not appear to. Simple re-sizing of the existing bypass channel keeps any future flooding problems close to the mill properties and the power lines crossing the site. Creating a new high level bypass overcomes those two issues, and allows the river to utilise part of the flood plain to attenuate flows which benefits properties at risk downstream in Lyng. The new channel can incorporate fish passage measures as well as in-channel habitat improvements.

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Figure 6.1 - Location of sub-reaches within Reach 14 (Elsing Reach)

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Figure 6.2 - Conceptual restoration plan for Reach 14a (Elsing Reach: Swanton Morley Mill structures to Hillhouse Farm)

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Figure 6.3 - Conceptual restoration plan for Reach 14b (Elsing Reach: Hillhouse Farm to Penny Spot Beck) Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 93

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Figure 6.4 - Conceptual restoration plan for Reach 14c (Elsing Reach: Penny Spot Beck to Elsing Mill) Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 94

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6.4 Reach 15: Swanton Morley Reach Table 6.10 presents a brief description of the existing conditions of the reach as observed during the site visit conducted on 13th and 14th January 2011. The purpose of the visit was to consider the reach objectives on the ground. Table 6.10 - Significant features and possible measures observed for Reach 15 during site visit (January, 2010)

Noted Feature Possible Measure Remove one or both weir structures to improve flow conditions, aid fish passage and remove Reach is significantly affected by the backwater effect. Need to assess impacts of backwater created by in-stream weir lowered water levels on floodplain lakes and structures associated with the site of fisheries. Swanton Morley Mill (Plates 1, 2 and 32). Fish pass provision at one, or both, of the gauging stations needs to be considered alongside restoration works. Retro fit fish passage structure to one or both Gauging sites at 2 and 3 Arch bridges structures (in Reach 14). Potentially present obstruction to flow and are likely to decommission both structures and build new impede fish passage due to presence of gauging site below confluence of main river with weirs (Plates 3, 5 and 6). integrated fish pass or provide alternative gauging system that does not require head drop. Complement existing restoration works through Successful in-stream and marginal provision of habitat connectivity to any new restoration works conducted along works. Improve performance of existing gravel approximately 900m of reach, including installations through reduction of backwater installation of gravel glides and fish refuges. effect. Limited freeboard at lake complex which had Increase freeboard by lowering water levels resulted in a breach to the TLHB at the time through works at Swanton Morley Mill weirs. of visit in January 2011. It was clear that Selectively remove / reduce embankment height previous breaches have occurred to the on TLHB below Billingford Covert to reduce risk TRHB as indicated by the line of sandbags of breach at lake complex. (Plate 28). Meander amplitude in upper section of reach Create in-stream habitat and flow diversity uncharacteristically small resulting in lack of through installation of berms and deflectors. sinuosity compared to the lower section of Option to raise bed through gravel placement in the reach. conjunction with channel narrowing measures. Some self-narrowing through marginal berm Considered that physical works such as use of development, but this is limited in width due deflectors and berm creation will be required to to historic over deepening. The result is narrow the channel due to over deepening. long, unconsolidated narrow berms. Move silt by change in flow patterns. Encourage Extensive lengths of siltation throughout the selective marginal vegetation encroachment as reach. silt management measure. Encourage high flow events on to the available Floodplain storage significantly reduced by floodplain area to the south of Billingford Covert. the presence of gravel pit lakes in the This can be achieved through the selective downstream section of this reach. These removal / reduction in embankment height on the occupy 52% of the reach’s 1 in 100 year TLHB and landscaping to provide flow route to flood outline. existing IDB drain. IDB drain occupies historic position of the Feed part, or all, of the flow through a modified river in the downstream section of the reach. channel. A wooded cut-off meander occurs to the Can be utilized as a high level channel to Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 95

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Noted Feature Possible Measure TLHB opposite Riverside Farm (Plate 22). increase conveyance past farm, to reduce flood risk, and provide damp habitat under normal flows.

6.4.1 Review of Reach 15 Strategy Objectives Appendix A to the RWRS (JBA, 2007) details a ‘Reach Restoration Strategy’ for each reach. These objectives have been the starting point for the consideration of rehabilitation activities within each reach. A review of these objectives is presented below in Table 6.11. Table 6.11 - Review of strategy objectives and recommendations for Reach 15 RWRS Objectives Atkins Comments on the RWRS Partially Agree: Flows split between the All works must integrate with lowering of main river and mill bypass under quite structures at Swanton Morley Mill and moderate flows anyway. Some 1.1 associated river works and must link improvement possible by further formalising with previously completed schemes. this feature. This will lower water levels upstream and link to previous schemes. Partially Agree: Change in flow regime De-silt channel just upstream of due to lowering/bypassing of structures 1.2 Swanton Morley structures and combined with use of woody debris will augment bed with gravels. provide natural de-silting, and better conditions for judging gravel need. Encourage channel to narrow naturally Agree: Some natural narrowing occurring; 1.3 by developing marginal / bankside encouragement would decrease time to vegetation. reach equilibrium width. Disagree: The width of land between the river and the gravel pits is very narrow, and the soil type is likely to have a high proportion of sand and gravel, which in turn Plant trees on outer bends to prevent will be porous and with poor physical 1.4 breaching into gravel pits. strength. Tree roots are likely to provide an ideal pathway for water to flow through the bank promoting settlement and consequent breaching. Breaching is better prevented by using appropriate bankside vegetation. Agree: Once the river emerges from the Introduce coarse woody debris confines of the gravel pits, increased scour 1.5 structures in the downstream section of due to placement of in-channel woody the reach to encourage scour. debris would benefit natural form and function with low risk. Partially Agree: Situation needs to be Initial work required is for bed and bank monitored but progressive stabilisation associated with lowering of lowering/diversion will allow bank vegetation 2.1 Swanton Morley Mill structures at the to stabilise banks. Bed unlikely to become downstream end of the reach. deeper through scour due to previous over- deepening. Appropriate measures required to 2.2 manage silt deposits upstream of the Partially Agree: As per comments on 2.1. mill. Partially Agree: More gravel glides are Reduce depth by an average of 0.4m needed through the reach, but unlikely to 2.3 and raise the bed by using up to 34 need 34. Heights to be judged once mill gravel glides or riffles in this reach. structures modified or bypassed.

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RWRS Objectives Atkins Comments on the RWRS Agree: Restoration should allow natural Assume reach will narrow naturally in form and function to prevail. Given the low time. Adopt / maintain maintenance 2.4 energy of the river this should not present regime and riparian management to problems, but would be easily disrupted by allow channel to narrow naturally. inappropriate intervention. Post-project monitoring is required, Agree: Any of the works require pre and 2.5 especially in association with works at post change monitoring to ensure outcomes the mill structure. are as expected. Summary Reach 15: Atkins agrees or partially agrees with all but one of the principles established by JBA for this reach. The one disagreement relates to the use of tree planting for bank protection through the gravel pits. The encouragement of natural narrowing and creation of free flow can be achieved by modifications to the mill structures and utilisation of other existing channels.

6.4.2 Reach 15: Recommended restoration This section provides the details of the options and measures proposed for this reach which have been derived from the Multi-Criteria Analysis (refer to Section 5.3). A summary of the MCA results in their rank order is provided at a reach scale in Table 6.12 and these are further divided into importance according to how far the measure will move the reach towards achieving ‘unfavourable recovering’ or ‘favourable’ ecological condition. Table 6.12 - Recommended restoration options for Reach 15 Option Description Weighted Score Highly Important Measures 5.7g Gravel glides 13.74 Important Measures 5.16 Berm creation 11.18 5.13 Deflector 10.53 5.4m Mill structures – remove all 9.44 5.17 Backwater – reconnections 9.22 5.14 Lower spoil embankments 8.35 5.15 Channel re-sectioning 8.27 5.11 Tree planting 7.91 G3 Targeted maintenance 7.36 5.18 Backwaters - new 7.11 5.12 Tree thinning 5.21 Less Important Measures 5.10 Fencing 4.39

6.4.3 Targeted maintenance Following the principles established in section 6.2.2 the following measures are suggested and may form part of the targeted maintenance protocol being developed for this unit. These include: 1. Silt removal. This is recommended immediately upstream of structures, or where silt deposits will limit discharge at confluences with IDB drains or significant tributaries. There are four structural arrangements in this reach. They are the two gauging stations under the 3 Arch and 2 Arch bridges, Swanton Morley Mill weir structure and the old mill bypass control structure 250m upstream of the mill. Monitoring and clearance of encroaching silt will be needed within 5m upstream and 10m downstream of the structures. As per the rest of the Wensum this is equal to one channel width and two channel widths, respectively. 2. Clearance of main channel downstream of confluence with IDB drains. There is one confluence with an IDB drain in this reach, just downstream of the Swanton Morley Mill Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 97

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bypass channel weir. There is also a requirement for inspection and clearance of encroaching marginal vegetation at connections to off-channel backwaters, such as that proposed by Riverside Farm. 3. Clearance or realignment of fallen trees blocking channel. Clearance is only required where they are impacting directly on flood risk to property or the structural integrity of third party assets. Any fallen trees upstream of aforementioned bridges need to be considered on their individual merit depending on the proximity of the bridge. 4. Strategic weed cutting. This is only needed where there is direct threat to houses caused by elevated water levels, or where freeboard or flood plain availability is unlikely to be sufficient to receive likely rainfall. Neither is considered likely on this reach, and therefore, no inspection or works are identified.

6.4.4 Restoration Measures The majority of the restoration measures identified by the MCA have been incorporated into the preferred outline restoration design for Reach 15, which is shown in Figure 6.5. Of the restoration measures selected for this reach, the only highly significant one is: Gravel glides Gravel glides have already been added to the top 1/3 of the reach with benefits to fisheries and natural form and flow function. Existing channel widths are not as excessive as seen elsewhere in this unit, which allows this form of localised bed raising to be effective. It will complement well the existing natural sections of gravel glides seen in the middle 1/3 of the reach and with the restoration works already undertaken. Similarly, they will work well with the lowering of spoil embankments to manage flood flows through the reach.

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Figure 6.5 - Conceptual restoration plan for Reach 15 (Swanton Morley Reach) Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 99

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6.5 Reach 16: Elmham Reach Table 6.13 presents a brief description of the existing conditions of the reach as observed during the site visit conducted on 13th and 14th January 2011. The purpose of the visit was to consider the reach objectives on the ground. Table 6.13 - Significant features and possible measures observed for Reach 16 during site visit (January, 2010)

Noted Feature Possible Measure Split channel: main channel through mill, with bypass to north. Main channel throttled This channel provides the route for discharge by mill, with typical mill pool below mill, through the mill, with some existing varied followed by shoal downstream and deep habitat. Better results will be achieved on the meandering channel to confluence with bypass channel. bypass. Bypass channel has scour pool below Adopt selective tree felling and use large woody control structure, and then runs straight but debris to construct flow deflectors to improve in- shallow with good speed to confluence. stream flow variation. Heavily shaded from TRHB (Plate 33). Combined channel turns through sharp bend with classic pool to outside of bend with Enhance self narrowing pattern with a berm shallow berm to inside. From there until combined with gravel glides to provide more Billingford Road Bridge, marginal vegetation appropriate bed level and habitat. is establishing a meandering pattern, but has still not reached equilibrium width (Plate 35). From the Road Bridge to the Black Water (Wendling Beck) confluence, plan form, width and cross sectional area appear Tree trimming would improve light conditions and natural with marginal vegetation establishing allow bank protecting vegetation to grow. where light levels allow. Shaded upstream of the old road bridge (Plate 37). Black Water confluence with Wensum Placement of deflectors upstream to push perpendicular to Wensum due to diversion Wensum flow to TLHB to create slack water caused by gravel workings (Plate 38). facilitating discharge of Black Water. Combine Eroding banks occur upstream of the with upstream bank protection works where confluence. appropriate. Good habitat downstream of confluence due to good natural gradient, and appropriate Trim local vegetation and use berms to provide width. Some erosion to TRHB due to flow flow changes. turbulence generated by local vegetation (Plate 41). Use berms and gravels to encourage more flow through meander, combined with some Reclaimed old meander needs better excavation and remove obstruction at proportion of flow to maintain self cleaning downstream end. Only progress if part of (Plate 42). integrated package of restoration work for this section of channel. Downstream of old gravel pit the gradient Use berms to horizontally narrow the channel reduces, resulting in an homogenous flow of and gravel glides to vertically reduce cross reduced velocity. section to energise the flow. River is against the edge of the floodplain to Selectively remove embankments which prevent the TLHB, whilst to the TRHB, floodplain out of bank flow utilising land on flood plain, Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 100

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Noted Feature Possible Measure storage significantly reduced by the hence reducing the loss of effective storage. presence of gravel pit lakes. These occupy 41% of the 1 in 100 year flood outline.

6.5.1 Review of Reach 16 Strategy Objectives Appendix A to the RWRS (JBA, 2007) details a ‘Reach Restoration Strategy’ for each reach. These objectives have been the starting point for the consideration of rehabilitation activities within each reach. A review of these objectives is presented below in Table 6.14. Table 6.14 - Review of strategy objectives and recommendations for Reach 16 RWRS Objectives Atkins Comments on the RWRS All works must integrate with lowering of Partially agree: Impoundment from structures at Swanton Morley Mill and Swanton Morley Mill structures appears not 1.1 North Elmham Mill and associated river to affect flow in this reach therefore works. integrate with North Elmham Mill only. Works must link with the completed Agree: Additional restoration measures 1.2 meander loop connection at Billingford linked to the reconnection will ensure long- and take flood risk into consideration. term functioning of the meander loop. Agree: Development of marginal Develop marginal / bankside vegetation vegetation and addition of gravel to the 1.3 and augment bed with gravels. stream bed will improve habitat and flow diversity. Agree: Removal of spoil embankments in the downstream section of this reach will Remove embankments to reconnect reinstate natural floodplain processes and 1.4 river to its floodplain. provide valuable flood water storage areas, though the impacts on stillwater fisheries will need careful consideration. In the 100 to 200m downstream of North Elmham Mill and in the immediate scour Agree: Reach immediately downstream of pool area of good habitat value, no mill is likely to provide good fisheries habitat 2.1 works are required and this area should on account of scour pool and well be conserved and allowed to re- oxygenated water. vegetate naturally. Partially Agree: Gravel glides are required Augment bed on average by 0.5m using in parts of the reach to replace the lost local gravels wherever possible and 2.2 gravel bed, but with significant sections with create up to 20 glides or riffles in the good gravel remaining large numbers reach. should not be required. Partially Agree: Natural narrowing through Assume reach will narrow naturally in vegetated berm development is evident in time. Adopt / maintain maintenance the reach although the downstream section 2.3 regime and riparian management to is considered to require physical narrowing allow channel to narrow naturally. devices on account of the width and depth of the channel. Summary Reach 16: Atkins agrees or partially agrees with all of the principles established by JBA for this reach. The two partial disagreements relate to the degree of intervention in the reach, not the principle or type of intervention.

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6.5.2 Reach 16: Recommended restoration This section provides the details of the options and measures proposed for this reach which have been derived from the Multi-Criteria Analysis (refer to Section 5.3). A summary of the MCA results in their rank order is provided at a reach scale in Table 6.15 and these are further divided into importance according to how far the measure will move the reach towards achieving ‘unfavourable recovering’ or ‘favourable’ ecological condition. Table 6.15 - Recommended restoration options for Reach 16 Option Description Weighted Score Highly Important Measures 5.7g Gravel glides 12.33 Important Measures 5.13 Deflectors 8.82 5.16 Berm creation 8.62 G3 Targeted maintenance 7.23 5.14 Lower spoil embankments 7.30 5.18 Backwaters - new 6.81 5.15 Channel re-sectioning 6.31 5.11 Tree planting 5.9 Less Important Measures 5.20 Changing primary and secondary channels 5.50 5.10 Fencing 3.90 5.12 Tree thinning 3.81

6.5.3 Targeted maintenance Following the principles established in section 6.2.2 the following measures are suggested and may form part of the targeted maintenance protocol being developed for this unit. These include: 1. Silt removal. This is recommended immediately upstream of structures, or where silt deposits will limit discharge at confluences with IDB drains or significant tributaries. The only significant structure on this reach is the Billingford Road Bridge. The abutments to the old (demolished) Billingford Road Bridge do not fall within this category as they do not facilitate silt deposition, whilst the access bridge to Elmham Mill has flows under it limited by the mill, so can also be considered to be less significant. Monitoring and clearance of encroaching silt will be needed within 5m upstream and 10m downstream of Billingford Road Bridge, which will also cover the IDB drain confluence. As per the rest of the Wensum this is equal to one channel width and two channel widths, respectively. 2. Clearance of main channel downstream of confluence with IDB drains and tributary rivers. There is one confluence with an IDB drain in this reach, immediately upstream of Billingford Road Bridge on the TLHB. The Black Water, a tributary stream, joins the TRHB of the Wensum half way along the reach. There is also a requirement for inspection and clearance of encroaching marginal vegetation, if required, at connections to off-channel backwaters such as the re-connected meander loop opposite the fishing lake. 3. Clearance or realignment of fallen trees blocking channel. Clearance is only required where they are impacting directly on flood risk to property or the structural integrity of third party assets. Any fallen trees upstream of any of the aforementioned bridges need to be considered on their individual merit depending on the proximity of the bridge. 4. Strategic weed cutting. This is only needed where there is direct threat to houses caused by elevated water levels, or where freeboard is unlikely to be sufficient to receive likely rainfall. Neither is considered likely on this reach, and therefore, no inspection or works are identified.

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6.5.4 Restoration Measures All the restoration measures identified by the MCA have been incorporated into the preferred outline restoration design for Reach 16, which is shown in Figure 6.6. Gravel glides The introduction of gravel in the form of short raised glides is to provide more typical gravel bed habitat and form. This will then link with those sections of bed where, by Wensum standards, there is a good existing gravel bed with the added benefit of appropriate flows. The addition of the glides, combined with those sections with natural gravel bed, should provide virtually the whole reach with bed type and flow appropriate for the river’s designation.

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Figure 6.6 - Conceptual restoration plan for Reach 16 (Elmham Reach)

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7. Cost Estimate

This chapter covers the cost estimate for delivering the preferred restoration options/measures for each reach as outlined in Chapter 6. To set this in context, a brief background history of previous published reports and their cost estimates is summarised in Section 7.1. Current estimates for reaches 14 to 16 following the MCA analysis and concept design are presented in Section 7.2 together with the main assumptions for the estimates. Potential cost savings are presented in Section 7.3 and delivery or phasing aspects are detailed in Section 7.4. 7.1 Previous cost estimates

7.1.1 Background Two previous reports, the RWRS (JBA, 2007) and Estimating Costs of Delivering the River Restoration Element of the SSSI Target (Halcrow, 2008), included some costs for restoration options on the river. The JBA RWRS report provided costs per kilometre of in-channel river works including bed raising, channel narrowing and restoring meanders. Based on these rates and the recommendations in the report for Unit 51, this equates to the costs outlined in Table 7.1. Table 7.1 - RWRS Unit 51 cost estimate (JBA, 2007)

Reach 14 15 16 Reach length: m 4830 2520 1170

Length of recommended works: 4.83 2.52 1.17 km Restoration £ n/a £ n/a £ n/a Narrowing <10 m £966,000 £504,000 Narrowing >10 m

Bed raising £293,400 £147,600 £75,600 Landscaping £4,830 £- £1,170 Fencing £28,980 £15,120 £7,020

Modification of mill

structures Total for reach: £293,210 £666,720 £83,790 Cost for unit: £2,043,720 Note: Estimates of total river restoration and rehabilitation costs assumed from JBA 2007 Technical Report Appendix A.

The Halcrow 2008 report covers all river SSSIs in England and includes the prevailing views of Natural England and the Environment Agency regarding appropriate measures for each unit on each river. A summary of the Halcrow costs for Unit 51 are presented in Table 7.2.

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Table 7.2 - Halcrow PSA Unit 51 cost estimate

Unit 51 LWD Fencing Fencing Structure Structure In-stream Structures Structures Meandering Meandering Bed Raising Modifications Modifications Cross Section Section Cross

Length requiring 0% 5% 5% 30% 30% 60% 0% work

Length in km 0.00 0.43 0.43 2.56 2.56 5.11 0.00 requiring work

Total cost (£) per - 25,624 103,096 75,465 194,716 206,707 0 km/length

Cost per unit per - 10,916 43,919 192,888 497,693 1,056,688 - activity (£)

Cost for unit: £1,802,103

A comparison of JBA and Halcrow cost estimates is presented in Table 7.3. This shows that the cost estimates to restore Unit 51 of the River Wensum range between £1,800,000 and £2,000,000. This feasibility report has looked at all options for restoration in more detail and hence it is appropriate that the costs for the recommended options are refined further. Table 7.3 - Comparison of cost estimates between JBA and Halcrow reports for Unit 51

Unit 51 LWD Total (£) Total (£) Structure In-stream In-stream Structures Structures Restoration Restoration Bed Raising Modification Modification Modification Cross-section Cross-section

RWRS cost estimates - - 1,470,000 516,600 57,120 - 2,043,720 (£)

SSSI cost estimates 10,916 43,919 192,888 497,693 - 1,056,688 1,802,103 (£)

7.2 Present cost estimates

7.2.1 Unit 51 cost estimate Costs for implementing the recommended options and measures for the whole of SSSI Unit 51 have been estimated based on information from the RWRS (JBA, 2007), SSSI Estimated Costs Report (Halcrow, 2008) and other sources. Making use of previous cost estimates where appropriate has ensured consistency in the cost estimates so that the feasibility report provides a refined cost estimate rather than an independent one. Table 7.4 shows the revised total cost estimate for the different river restoration measures recommended for Unit 51. This estimate is based on a number of assumptions relating to sizes,

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quantities, materials and conditions. It also reflects current prices and costs which may have changed since the JBA and Halcrow reports were carried out. The targeted maintenance option has not been costed due to uncertainty in rates. This exclusion, along with the assumptions, will affect the accuracy of the final cost estimate. The full details of the costs and assumptions are given in Appendix B. Table 7.4 - Unit 51 cost estimates for various river restoration measures (January 2012)

Measure Description Quantity* Rate (£) Cost (£) 5.1 Fencing (m) 8,520 8 68,160 5.16 Berm creation (m) 1,253 90 112,806 5.15 Channel re-sectioning (m3) 797 14.18 11,297 5.12 Tree felling (m) 285 10 2,850 Backchannel – 5.17 7,998 14.18 113,409 reconnection (m3) 5.7g Gravel glides (m3) 5920 53 313,760 5.19 Channel realignment (m3) 1485 9.83 14,602 5.13 Deflector (m) 254 44 11,176 5.11 Tree planting (unit) 280 58 16,240 5.14 Embankment lowering (m3) 787 9.83 7,736 Other Plugs (m3) 1107 53 58,672 Option G3 Targeted maintenance - Unknown - Cost for unit: £730,708

Table 7.5 shows the cost estimates for each reach and restoration measure.

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Table 7.5 – Unit 51 cost estimates for each reach and restoration measure

Description Sub- Sub- Sub- Reach Reach Reach Total (£) reach reach reach 14 (all) 15 16 14a 14b 14c

Fencing 7,040 22,560 9,040 38,640 20,160 9,360 68,160

Berm creation 19,764 55,998 16,470 92,232 9,882 10,692 112,806

Channel re- - - - - 6,726 4,571 11,297 sectioning

Tree felling - 1,550 - 1,550 - 1,300 2,850

Backchannel – 28,127 37,827 11,154 77,108 32,862 3,439 113,409 reconnection

Gravel glides 112,890 - 3,498 116,388 144,690 52,682 313,760

Channel 14,602 14,602 14,602 realignment

Deflector 2,156 - 2,156 4,312 - 6,864 11,176

Tree planting 2,320 2,900 2,320 7,540 - 8,700 16,240

Plugs 29,336 - 29,336 58,672 - - 58,672

Targeted Yes Yes Yes Yes Yes Yes Unknown maintenance

Lower 737 737 2,212 3,686 2,792 1,258 7,736 embankments

Total costs: £216,972 £123,728 £74,030 £414,730 £217,112 £98,866 £730,708

7.3 Potential cost savings The total cost estimate to the nearest thousand of £731,000 for Unit 51 is based on a number of assumptions, in particular the materials and installation methods for the various recommended river restoration measures (see Appendix B for further details). Should alternative restoration measures be implemented, this may affect the total price outcome. Efficiency savings could be achieved by re-using, where appropriate, spoil generated as part of the restoration works to construct features that require spoil. The following section identifies potential means of reducing costs associated with spoil disposal. 7.3.1 Spoil reduction A number of the river restoration measures for Unit 51 generate spoil as outlined in Table 7.6.

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Table 7.6 - Options that typically generate or require spoil

Reach Total 14a 14b 14c 15 16 Spoil (m3) Generation (m3) Berms 509 1,442 183 110 119 2,363 (require spoil) Re-sectioning - - - 474 322 796 (generate spoil)

Backchannel reconnections 1,984 2,668 787 2,318 243 8,000 and creation (generate spoil)

Channel realignment - - 1,485 - - 1,485 (generate spoil) Plug 554 - 554 - - 1,108 (requires spoil) Lower embankments 75 75 225 284 128 787 (generate spoil) Total surplus 996 1,301 1,760 2,966 574 7,597 spoil (m3): Opportunity to Yes Yes Yes Yes Yes Yes reduce spoil

Table 7.6 shows there is potentially a significant amount (around 7,597m3) of surplus spoil volume for the whole unit. Whilst some spoil may be lost on site there are opportunities to replace some of the gravel requirements with spoil on reaches and sections of reaches where this is suitable. This might include depth substitution within gravel glides (i.e. using spoil rather than gravel in constructing the lower layers of glides – see section 7.3.2) where practicable. Any reduction in spoil disposal will reduce the amount of trafficking on site to dispose of the material. Opportunities to reduce spoil generation and movement should be sought during the detailed planning and construction phases. This will have beneficial consequences in terms of reduced:  Land take  Cost  Carbon footprint  Grounds for landowner dissatisfaction  Need for environmental mitigation. For the channel realignment and new backchannels connections excavation lengths cannot be meaningfully reduced as they need to maintain recommended size to provide long term stability.

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7.3.2 Gravel glides The MCA identified that the most beneficial measure of reintroducing gravel to the system was in the form of gravel glides which have been recommended for all the reaches in Unit 51 (14, 15 and 16). Gravel glides account for 6% of the total option costs, a total estimate of around £25,000. Depth substitution: Surplus spoil has to be disposed of so could be used in part to substitute for two thirds of the gravel volume to the gravel glides. The reduction in costs comes from the reduction in volume of gravel used, as presented in Table 7.7. Table 7.7 - Gravel substitution using surplus fill

Reach Surplus No. Opportunity Volume of Gravel Total Totals Spoil Glides to substitute replaced by Spoil Volumes Volume gravel with per glide (2/3 of Saved excess spoil Total Glide Volume) (m3) 14a 996 5 Yes 284 996* 14b 1,301 - n/a - - 14c 1,760 3 Yes 15 45 15 2,966 15 Yes 121 1,815

16 574 7 Yes 95 574* Total measure: 3,430 Gravel cost £/m3: 53

Spoil disposal cost £/m3: 4.81

Cost for unit: £198,288 Note:*indicates where all of potential surplus spoil is used in gravel replacement.

The total achievable cost savings associated with reducing the gravel requirement through spoil utilisation in gravel glides is as follows:  A reduction in gravel costs and soil disposal costs of £198,288 which represents a saving of approximately 63% on the total gravel glide cost for Unit 51. Length substitution: Cost savings could be made by replacing some of the gravel with other material. However, substituting sections of the gravel glides with hurdles is only possible if the river bed system has mobile gravel substrate. Due to the historical channel dredging there is limited gravel in the existing channel so opportunities may be limited. However, during detailed design, surveys may identify the presence of gravel in the system, creating gravel cost saving opportunities.

7.3.3 Cost Saving summary: There are opportunities to make significant savings through replacing part of the gravel glide material through depth substitution. Should this method be implemented, this could reduce the total restoration cost by £115,472. This represents a total cost saving of 15.8% based on the original total cost estimate for Unit 51.

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7.4 Delivery Section 7.3 provides details of the costs for physical works, but this can be influenced by how the works are carried out. The following sections explore this further. Phasing: The phasing of the excavation measures can reduce the amount of double handling needed. This has benefits in reducing the amount of physical work required, and therefore:  Unnecessary disturbance and damage to the environment.  Less disruption risk due to bad weather or poor ground conditions.  Reduction of scheme costs. It is recommended the works be phased in the order listed in Table 7.8 Table 7.8 – Recommended phasing of works

Phasing Measure Reason for Phased Order Provides flood risk management, silt control and 1 Targeted maintenance confirms Environment Agency presence on the river. Highly important for project delivery, immediately Backwaters and lower 2 helps with fish recruitment and flood risk, and embankments generates large volumes of spoil.

Must follow spoil removal to access the river banks, the two previous operations will generate 3 Berm creation the arisings with which to complete berm creation. The impact of berms on flow and level can be 4 Re-sectioning assessed and so inform the required re-section depth.

Previous measures have improved in-channel 5 Tree thinning conditions to allow macrophyte growth, and so tree thinning is now required to remove shade.

Tree thinning and felling provides raw material for 6 Deflectors the deflectors, and re-sectioning has improved channel capacity. Realignment / Changing The impact of berms and deflectors on flow 7 primary and secondary patterns can be assessed to inform the extent to channels which realignment is needed. With all previous in-channel works, and any silt release completed, smaller gravel works can be 8 Gravel glides placed in the channel at the best locations and shaped for maximum impact.

With all the in-river features in place the location for the trees can be easily seen, and without 9 Tree planting further works the trees are unlikely to be damaged. If this is not done last, any further works will 10 Fencing require its removal and re-construction.

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7.4.1 Monitoring The details for river monitoring need to be agreed between Natural England and the Environment Agency before any restoration measures commence on site. Monitoring will have to commence before restoration works start to collect baseline data. Monitoring will also allow a comparison of changes to be recorded as each phase is implemented. 7.4.2 Maintenance If there are time gaps between the implementation of different restoration measures, then ‘Targeted Maintenance’ will help manage the river appropriately until works can commence. 7.4.3 Local resources If the implementation of the works is to be phased geographically, then there is merit in including the landowners in the tendering list, as they may have the necessary resources to complete the excavation and spoil movement and spreading. This would bring unrivalled local knowledge to bear on each river reach subsection, and would open-up opportunities that other contractors would not be able to realise. 7.5 Summary Table 7.9 summarises the recommended restoration measures, in order of phasing, for Unit 51.

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Table 7.9 - Recommended phasing of restoration measures for Unit 51

MCA Score Option Measure Phasing Reach 14 Reach 15 Reach 16 ‘Targeted G3 1 8.98 7.36 7.23 maintenance’ 5.18 Backwaters - new 7.92 7.11 6.81

Back channel 5.17 9.05 9.22 n/a reconnection 2

Lower 5.14 / 5.21 7.41 8.35 7.30 embankments 5.16 Berm creation 3 12.03 11.18 8.62 5.15 Re-sectioning 4 n/a 8.27 6.31 5.12 Tree thinning 5 5.88 5.21 3.81 5.13 Deflectors 6 9.83 10.53 8.82

5.19 Realignment 10.21 n/a n/a

Changing primary 7 5.20 and secondary 4.33 n/a n/a channels 5.7g Gravel glides 8 7.03 13.74 12.33 5.11 Tree planting 9 6.22 7.91 5.9 5.1 Fencing 10 4.95 4.39 3.9 Mean 7.22 8.48 7.10 Highly important 10.03 11.96 10.58 Less important 5.80 5.15 5.74

The key points to note are:  The phasing relates to the order of installation, not to the order of importance in delivering the changes in form and process to the main river channel.  The scores derived from the MCA provide the method for placing each measure in relation to each other measure to give the combined final design that provides the best delivery in the long-term.  The design for each reach is related to the conditions within the unit and takes account of the changes in other reaches that have inter-reach impacts, such as mill structure backwater effects.  The phasing is independent of the length of river being worked. The cost estimate for Unit 51 is £731,000 (to the nearest thousand) which is considerably less than previous reports. However, although a cost saving may be achievable, this will be very much dependent on the findings at the detailed design stage once a review of additional site specific survey information (bathymetric and topographic) and utilities searches are carried out. This revised estimate is less

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than previous cost estimates (JBA, 2007; Halcrow, 2008) although it is difficult to compare the three estimates due to the assemblage of different components. There also needs to be allowance made for different dates of each estimate. Table 7.10 summarises the differences between the three different cost estimates. Table 7.10 - Comparison of costs between 2007, 2008 and 2011 studies

Halcrow (2008) JBA (2007) Atkins (March 2011) Length Cost Length Cost Length Cost (km) (£) (km) (£) (km) (£) Fencing* 0.00 - 8.52 51,120 8.52 68,160 Large woody debris 0.43 25,624 0.254 11,176 In-stream structures 0.43 43,919 1.283 171,478

Cross section 2.56 192,888 7.35 1,470,000 1.119 19,033 modifications Bed raising 2.56 497,693 7.35 516,600 0.65 313,760 Landscape** 7.35 6,000 0.565 19,090 Reconnections 1.295 113,409 Restoration 0.00 - - - 0.35 14,602

Structure 5.11 1,056,688 - - 0 - modification/Other Totals (excl.fencing) 11.08 1,816,811 22.05 1,992,600 5.516 662,548

Atkins total estimate for Unit 51 (including fencing): 730,708

Overall unit rate: 213,241 233,873 85,764 £/km Density of features 1.30 2.59 0.65

Density adjusted 277,213 605,271 55,747 rate £/km Notes: *Fencing length excluded from the calculation of the total length of restoration features. **Includes tree felling and tree planting.

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8. Environmental Scoping 8.1 Introduction

8.1.1 The need for Environmental Impact Assessment The types of river restoration measures identified by this feasibility study are likely to fall within the Environment Agency’s permitted development rights under Schedule 2, Part 15(b), of the Town and Country Planning (General Permitted Development) Order 1995 SI 95/418 (referred to as the GPDO) and it is anticipated that planning permission will not be required. As the details of any future schemes are developed, consultation with the relevant local planning authorities regarding the proposals will be required to confirm this view. Any works that are undertaken under Schedule 2, Part 15(b) of the GPDO fall within the remit of the Environmental Impact Assessment (Land Drainage Improvement Works) Regulations Statutory Instrument (SI) 99/1783 (as amended by SI 2005/1399 and SI 2006/618). SI99/1783 (as amended) requires that the potential for the works to give rise to significant environmental effects is considered. Where significant environmental effects are likely to occur there will be a need to undertake an EIA (Environmental Impact Assessment) of the scheme. It is considered that the works within Unit 51 are unlikely to give rise to significant environmental effects, and will therefore not require a statutory EIA. This position will be confirmed by the Environment Agency during the detailed design phase for each scheme by an internal screening exercise. In accordance with the requirements of SI 99/1783 (as amended), the intention not to produce an Environmental Statement will need to be advertised. The advertising process will be undertaken once the details of any schemes have been developed, and the relevant local planning authorities have been consulted regarding the proposals. Although a statutory EIA (with the production of an Environmental Statement) is unlikely to be required, it is Environment Agency policy to undertake EIA for its own works. Therefore, a risk- based non-statutory environmental assessment for any subsequent restoration schemes will be undertaken, and this will be documented by an Environmental Report. 8.1.2 Environmental Scoping Exercise As part of this feasibility report, an environmental scoping exercise on the preferred restoration option for each reach was undertaken. The purpose of this exercise was to determine what issues will need to be considered during the Environment Agency’s non-statutory EIA for any forthcoming restoration scheme. The scoping exercise will also form part of the required documentation to gain internal approval for the scheme. The purpose of the environmental scoping exercise is to:  Provide a record of the scoping process.  Identify the methodology for undertaking and evaluating the EIA.  Identify what environmental issues will be scoped into the EIA.  Identify what environmental issues will be scoped out of the EIA.  Identify environmental constraints and opportunities that will need to be addressed at the detailed design stage.  Consult with statutory bodies and interested parties on the proposed scope. Whilst there is no formal requirement for scoping to be undertaken in the (IEMA, 2004), environmental scoping is a fundamental component of the EIA process because it identifies the key environmental issues and avoids progressing issues that are considered to be

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less important through to the next stage of EIA (IEMA, 2004). Figure 8.1 illustrates where environmental scoping occurs within the EIA process, and how this has been applied to Unit 51.

Environmental Scoping: Unit 51: North Elmham Mill to Elsing Mill

SCHEME CONCEPT Understand and establish key project drivers and objectives of the Feasibility Assessment.

SCREENING Define the environmental baseline features of each reach in Unit 51. Considers a number of ‘River restoration’ and ‘Targeted maintenance’ options and measures that could be applied and implemented individually or in combination to restore Unit 51 to ‘unfavourable recovering’ or ‘favourable’ ecological condition.

CONSULTATION & RESULTS & ANALYSIS

Communicate with key statutory stakeholders and the local community to capture the ‘big’ issues, and identify the constraints and opportunities of the proposed restoration measures.

Analysing the feedback obtained from the consultation process

MULTI CRITERIA ANALYSIS (MCA) WORKSHOP Apply the MCA tool against ecology, project delivery and technical aspects that help inform the selection of appropriate measures for Unit 51.

Use results of MCA and professional judgement to select recommended option(s).

SCOPING OF THE PREFERRED OPTIONS FOR UNIT 51 Focusing on the significant environmental issues associated with the proposed restoration measures.

SCOPED IN SCOPED OUT

Request a formal scoping opinion to the planning authority to inform the project team the level of EIA required.

Undertake either a full Environmental Impact Assessment or Environmental Report for each unit

Figure 8.1 - Environmental scoping within the EIA process

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8.2 Method of assessment The project is still at a strategic level, so detailed studies of baseline environmental conditions have not been carried out. This means that professional judgement, in combination with the methodology explained below, was used to determine what environmental issues will be assessed in more detail at the next stage of the EIA process. The options and measures that have been detailed in Table 8.2 require scoping for potential constraints and opportunities. To carry out this level of assessment, the European Commission guidance on Screening and Scoping (2001) has been adapted to determine what type of constraints and opportunities are likely to give rise to significant effects. Table 8.1 presents the framework for classifying and evaluating the significance of potential environmental effects of the preferred river restoration option. Table 8.1 - Classifying and evaluating the significance of potential environmental effects in the scoping process (adopted from European Commission, 2001)

Key Questions Used In Environmental Scoping Measure Are the final proposed works out-of-character with the local Yes / No environment? What is the scale of the effect? Limited / Widespread Is there potential for effects on the environment outside of study Yes / No area? Are there many people affected? Yes / No

Are there protected, rare or endangered features affected? Yes / No

Is there a risk of breaching industry standards? Yes / No

Probability of occurrence Yes / No

What is the length of the effect? Short / Medium / Long

Is the effect reversible? Yes / No

Significant effect (without mitigation) Major / Moderate / Minor

8.2.1 Restoration Options and Measures Restoration options and measures outlined in Table 8.2 have been grouped to simplify the scoping process and to avoid repetition in assessing effects. The groups are:  In-channel works; berm creation; gravel glides; channel re-sectioning; deflectors; channel realignment and lowering mill sill levels.  Floodplain works; lowering spoil embankments; reconnecting to existing floodplain surface water drainage; new backwaters and tree thinning.  Other works: ‘Targeted maintenance’, tree planting and fencing. Using the information within Table 8.1 and professional judgement, the recommended restoration options and measures are assessed in terms of their significance of effect. This report has adopted the following categories to determine significance of effect:  Potential adverse effect;  Neutral effect (or one that could be designed out); and  Potential positive effect.

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Using the results of Table 8.2, environmental issues are either scoped in or out. Issues that are scoped in will be carried through to the next stage of the EIA process. Issues scoped out are dropped from the EIA process but periodically reviewed should matters like scheme design elements change. Section 8.3 presents the results of the scoping assessment. 8.3 Results of scoping The scoping assessment was undertaken by using professional judgement and best practice literature (IEMA, 2004; and European Commission, 2001). It is considered to be in accordance with the legislation, procedure and guidance in force and with reference to international standards of EIA best practice. This section summarises the results of the scoping assessment. The scoping assessment included the opinions of public and private stakeholders captured during the initial public ‘drop-in days’ and various consultations with statutory stakeholders (refer to Chapter 4 for more information). The early consultation within the EIA process provided timely and appropriate opportunities for public and stakeholder involvement. One of the key outcomes of early engagement has been the identification for the need to implement targeted maintenance ahead of main river restoration works. The environmental scoping assessment has identified issues to be scoped in and out of the EIA process. Those issues scoped in to the assessment will require further assessment for their potential adverse or beneficial cumulative effect at the next stage of the EIA (detailed design). Table 8.2 summarises the potentially key adverse and beneficial impacts associated with the preferred restoration options for Unit 51. It provides more accurate information on exactly what data and actions are required for the next stage of the EIA assessment. Table 8.3 lists those environmental issues that were scoped into the next stage of the EIA, and Table 8.4 lists those issues that were scoped out. Information contained within Tables 8.2 to 8.4 ensures that the scope of the EIA will be focused only on key issues.

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Table 8.2- Environmental scoping assessment for recommended restoration options

Legend Potential adverse effect Neutral effect Potential positive effect

In-channel works Floodplain works Other works

Individual Environmental Scoped Environmental Phase Aspect of Proposed Works Giving Rise to Potential Impact Group In? Features m r Be Gravel Glide Channel Re- sectioning Deflectors to Connect Channels Channel Realignment Sill Lower Mill Levels Lower Spoil Embankments Re-connect to Floodplain Drains New Backwaters / Tree Felling Thinning Targeted Maintenance Fencing Tree Planting Construction activities include additional vehicle movements. The number of Heavy Goods Vehicles (HGVs) needed to transport the required gravel is low and transport will be Construction X undertaken over a short period of time. Therefore, adverse impacts to local ambient air Air quality quality are unlikely to be significant.

Operation No effects are anticipated for the operational phase. X

Restoration schemes have the potential to result in the release of atmospheric carbon. Air and Climate However, schemes will be designed to minimise the use of synthetic and imported Construction materials. Where possible, materials used will be from within the site or imported from a  local source to minimise carbon emissions associated with transportation. Waste will be Climate change minimised, and arisings will be reused on site wherever possible. The restoration measures proposed will be designed to adapt to future uncertainty. Tree planting has the potential to become a natural carbon sink, therefore offsetting the impacts Operation X of tree felling. However, the restoration is unlikely to have a significant impact on climate change and is therefore scoped out.

Construction works are likely to have a temporary negative effect on the local landscape. Tree felling and pollarding to improve river biodiversity and to provide woody debris for in- Construction channel works are likely to impact locally on landscape and visual amenity. However, the magnitude of these works is low, and tree planting within the floodplain will offset tree Landscape Landscape and removal in the long term. character & visual  visual amenity amenity Restoration of the river through introducing greater sinuosity or improvements to the riparian habitats should return the target reaches to a more natural state. Once Operation established, these works would be expected to improve the visual amenity value of the reaches through softening the “man-made” feel of certain sections of the river, especially those where the channel has been canalised and all sinuosity has been lost.

Physical works to the banks ( e.g. re-profiling, construction of berms, reduction in spoil banks to source gravels and reconnect to floodplain) as well as tree management and Construction  access and plant movements, have the potential to result in disturbance and/or damage to Protected species protected species and their habitats, such as water voles, otters, bats and badgers.

Ecological improvement of the river is the key objective of the project. Completed schemes Operation  are expected to result in long-term benefits for protected species. Works including bank re-profiling and bed-level raising have the potential to disturb in-situ Flora & Fauna sensitive aquatic species. Increasing the number and range of glides, riffles, runs, pools Construction and flow types will have adverse impacts on fish and aquatic populations during  construction but will provide significant long term improvements to the habitats available for Fisheries, a wide range of macro-invertebrates. invertebrates and Ecological improvement of the river is the key objective of the project. The works are likely flora to result in long term improved habitat for key aquatic fauna. This may include Desmoulin’s whorl-snail (Vertigo moulinsiana), bullhead (Cottus gobio), white-clawed crayfish Operation  (Austropotamobius pallipes) and brook lamprey (Lampetra planeri). One of the key PSA targets is the improvement of the Ranunculion fluitantis and Callitricho-Batrachion vegetation community which is characteristic of the river type.

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In-channel works Floodplain works Other works

Individual Environmental Scoped Environmental Phase Aspect of Proposed Works Giving Rise to Potential Impact Group In? Features m r Be Glide Gravel Channel Re- sectioning Deflectors to Connect Channels Channel Realignment Sill Lower Mill Levels Lower Spoil Embankments Re-connect to Floodplain Drains New Backwaters / Tree Felling Thinning Targeted Maintenance Fencing Tree Planting Construction of some restoration options may leave open areas of bare ground which may give rise to opportunistic invasive plants. Good construction and site management, Construction  including plant maintenance (e.g. vehicle cleaning) will be necessary to prevent the spread of such invasive species. Invasive and non- Reconnection to floodplain features (e.g. gravel pits, existing field drains and wetland pools) native species has the potential to spread invasive species such as Crassula, Azolla and signal crayfish. Any reconnections considered as part of the restoration will require a site specific Operation  assessment of existing constraints and control options. Invasive species recorded in this unit include Canadian pondweed, Elodea canadensis, the naturalised shrimp, Crangonyx pseudogracali and signal crayfish. There may be tree thinning and felling, during construction, to improve habitat diversity. Construction This has the potential to impact on visual amenity/landscape character. Trees Planting of additional trees will, in time, provide submerged roots for colonisation by  Operation numerous macro-invertebrate species, from caddis flies to crayfish. The surrounding landscape will also benefit from additional tree planting Short-term, physical changes to hydrology due to temporary works in the channel are not Construction likely to cause significant effects. Geomorphology Physical changes through excavations, bank re-profiling, bed-raising and infilling, works to  Operation improve sinuosity and channel narrowing. Improvements in field surface water drains through re-connecting the main river to these drains will improve surface water drainage. Construction Short-term increases in flood risk may occur due to temporary works in the channel.

Drainage and flood River restoration measures such as lowering mill sill levels, lowering spoil embankments,  risk channel re-sectioning and installing gravel glides all have the potential to change flood risk, Operation Water both locally and further afield. This will need assessment at the detailed design stage. Such changes could be negative or positive in terms of flood risk.

In-channel construction will disturb bank and bed sediments and result in the release of sediment to the river and temporarily reduce water quality. There is also a risk of Construction chemicals, oils or fuels being accidentally released into the environment during Water quality construction. 

Bed raising with gravels and the creation of new pool, riffle and glide sequences all have Operation the potential to improve existing water quality in the long-term.

Construction works are likely to have temporary impacts on public and private access to Construction  affected land, including angling access and footpaths.

The rehabilitation works would provide significant opportunities to improve river angling. Humans Lowering of mill sill levels (e.g. at Swanton Morley) has the potential to affect groundwater levels and hence the water levels in lakes used for angling. Canoeing: Whilst there are no Human Operation  statutory navigation rights on the River Wensum, where there is agreed access for Environment canoeists, impacts and opportunities will be assessed. Where there is no agreed access for canoeists, this will be treated like a normal constraint.

There may be temporary loss of land use for activities such as grazing, due to construction Land use Construction works. This is unlikely to result in significant environmental effects but will require careful X management with landowners to enable construction.

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In-channel works Floodplain works Other works

Individual Environmental Scoped Environmental Phase Aspect of Proposed Works Giving Rise to Potential Impact Group In? Features m r Be Glide Gravel Channel Re- sectioning Deflectors to Connect Channels Channel Realignment Sill Lower Mill Levels Lower Spoil Embankments Re-connect to Floodplain Drains New Backwaters / Tree Felling Thinning Targeted Maintenance Fencing Tree Planting Rehabilitation works may involve minor realignments of the river channel which may result in the permanent loss of a small amount of grazing land immediately adjacent to the river. The lowering of river banks and / or reconnection of the river to adjacent field drains may result in more frequent small scale flooding of the functional floodplain. However, the floodplain of the River Wensum is within the Broads ESA scheme so as to support Operation  extensive and traditional management regimes. Although the ESA scheme is closed to further entrants, the River Wensum is a target area with regard to Higher Level Stewardship. If changes in hydrological regime were to impact the feasibility of management prescriptions under existing schemes, then schemes would need to be modified.

Noise is expected to be created by construction works but this will be minimised through Construction mitigation and best practice construction techniques. There will be no operational noise X Noise & vibration associated with the development.

Operation No effects are anticipated for the operational phase. X

It is expected there will be a short term increase in traffic through local villages during Construction  construction as a result of importing materials to site. Traffic & transport Operation No effects are anticipated for the operational phase. X

Construction works are expected to have short-term adverse effects on local landscape Construction quality. However, construction related impacts will be short term and the visual amenity is X expected to improve in the medium to long-term. Landscape and Local landscape visual amenity character There may be long-term changes to the landscape character that will need to be assessed on a case by case basis. It is anticipated that naturalisation of the river will be an Operation  improvement, however, there may be instances where there are significant changes to existing landscapes of local or national significance.

Earthworks and construction may give rise to adverse effects on the historic environment. Construction Excavation of banks for channel realignment and the lowering of raised spoil embankments  Historic Cultural heritage may have adverse effects on unknown items of historic significance. environment Engineering works may have long-term adverse effects on mill buildings which are of Operation  historical and cultural importance.

There is potential for restoration works to result in large volumes of soil being removed or imported to site. An attempt will be made to balance cut and fill wherever possible to reduce soil demand and wastage. Demand for soil will be met by using local sources Construction  where practicable. Surplus soil (e.g. through the creation of berms and channel re- Soils sectioning) will be disposed of on the landholding where practicable and, if not, off-site as a form of waste.

Operation No effects are anticipated for the operational phase. X

Construction X The recommended restoration works are not likely to give rise to either adverse or positive Soils & Geology Geology effects on existing drift geology or deep geology. Operation X

Historical contamination: Desktop investigations have not revealed any significant historical industrial land use along the river margins other than that associated with mills. However, various samples taken at mills along the Wensum have failed to meet the waste Construction  Ground acceptance criteria required for landfill due to contaminants that are not covered by the contamination Soil Guidance Values. Further checks prior to construction would need to be made on the contaminants not covered by the Soil Guidance Values. No effects are anticipated for the operational phase. Operation X

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In-channel works Floodplain works Other works

Individual Environmental Scoped Environmental Phase Aspect of Proposed Works Giving Rise to Potential Impact Group In? Features m r Be Glide Gravel Channel Re- sectioning Deflectors to Connect Channels Channel Realignment Sill Lower Mill Levels Lower Spoil Embankments Re-connect to Floodplain Drains New Backwaters / Tree Felling Thinning Targeted Maintenance Fencing Tree Planting There is potential for restoration works to require waste materials to be removed from site. A Site Waste Management Plan will be implemented as part of the Environment Agency’s Construction X best practice approach to waste management. This will be produced separately to the EIA Waste Waste and therefore this issue is scoped out of the EIA. No effects are anticipated for the operational phase. Operation X

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Table 8.3 - Issues scoped into the EIA process

Environmental Individual Justification Group Environmental Features Air and climate Climate change The carbon impact of restoration measures will be considered in the design process and the assessment of different options will be reported in the EIA if considered to be significant. A carbon calculator will be maintained throughout the development and implementation of restoration measures. Construction work has the potential to adversely affect Protected species protected species such as water vole otter, bats and badger. Fisheries, The key impacts of restoration works on these species invertebrates and during construction and operation will need to be flora identified and assessed. Invasive species represent a threat to the structural Flora and fauna integrity of works, a risk to human health for both construction workers and the wider public, and also to Invasive and non- the natural environment by taking over habitats to the native species detriment of native plant and animal species. It can be very expensive to remove invasive species through removal and disposal of surrounding soil. Damage to trees may be caused by direct removal or Trees by changes in the soil character upon spoil removal or deposition. Physical changes from excavations on geomorphology Geomorphology need to be investigated in more detail at the next stage of the EIA. The impacts of local restoration schemes on flood risk Drainage and flood Water will need to be assessed, during both construction and risk environment once the project is operational. Construction in or near to water risks water quality being adversely affected by the mobilisation of silts or Water quality the accidental release of contaminants. The EIA will consider how these risks will be managed. There may be short term disruption to public and or private access during construction. The rehabilitation works may provide opportunities to improve river angling, but also have the potential to affect water Humans levels in nearby lakes used for angling. Whilst there are no statutory navigation rights on the River Human Wensum, where there is agreed access for canoeists, environment impacts and opportunities will be assessed. There may be temporary and permanent changes in land Land use use, including impacts on ESA agreements and other agri-environment schemes. It is expected that there will be a short-term increase in Traffic & transport traffic on the local road network during construction as a result of importing materials to site. Cultural heritage Historic The key construction and operational effects on cultural and archaeology environment heritage and archaeology need to be identified. The key construction and operational effects of the Landscape Local landscape restoration works on the landscape character and character and character visual amenity of the Wensum valley need to be visual amenity identified and assessed. The recommended restoration works are not likely to Soils & geology Soils give rise to either adverse or positive effects on existing

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Environmental Individual Justification Group Environmental Features soils. However, there may be issues relating to balancing quantities of supply (cut) and demand (fill) which have environmental implications. Ground There are risks of encountering contaminated material in all earthworks. This risk will need to be assessed during the contamination design phase.

Table 8.4 - Issues scoped out of the EIA process

Environmental Individual Justification Group Environmental Features There will be short-term, localised impacts on air quality during construction. These impacts are considered to be temporary and not significant enough to warrant further Air and climate Air quality investigation. Standard best practice in construction should be adequate to manage these impacts and therefore air quality will not be considered further in the EIA. Noise is expected to be created by construction works, Human but this will be minimised through mitigation and best Noise & vibration environment practice construction techniques. There will be no operational noise associated with the completed works. The restoration works are not likely to give rise to either Soils & geology Geology adverse or positive effects on existing drift geology or deep geology. It is unlikely that the proposed works will generate waste Waste N/A that will have to be managed through a waste exemption licence or be taken off-site.

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9. Consents

A number of consents and permissions are likely to be required in order to implement the recommended river restoration options and measures for Unit 51. These are listed in Table 9.1, together with the organisations that are responsible for granting them and a summary of the action needed as the EIA progresses. Table 9.1 - Likely planning consents and permissions

Likely Organisation Comment Consent

The Environment Agency has permitted development rights under the Land Drainage Act 1991 and Water Resources Act 1991 to carry out necessary restoration works within main rivers. The River Wensum is a main river so works within the channel Environment Agency do not require planning consent. The permissive rights extend to 9m either side of the main channel. Planning Local planning authorities will be consulted to permission determine if any aspects of proposed river restoration schemes require planning permission.

Planning permission will be obtained from the local authority if any works are not covered as ‘Permitted Local Planning Authority Development’ under Part 14, Schedule 2 of the Town & Country Planning (General Permitted Development) Order 1995.

The Environment Agency will screen individual Environmental restoration projects for their environmental risk. Impact In accordance with Works are not likely to require a full EIA Assessment Environment Agency EIA (Environmental Statement) but as best practice the (statutory / non policy. Environment Agency will carry out an appropriate statutory) level of environmental assessment.

If any of the works (particularly the mill works) involve alterations to listed buildings or structures, consultation with the relevant Conservation Officers Listed building from the local authorities will be required. A separate Local planning authority consent Listed Building Consent may be required from the local authority for works affecting listed buildings or structures. This should not affect permitted development rights.

Development and Flood Risk Team has been consulted and a Flood Defence Consent will be Flood Defence Environment Agency required. This may include the need for a formal Consent Flood Risk Assessment if planning permission is required.

Consent will be required from the Internal Drainage Norfolk Rivers Internal IDB Consent Board for any works to watercourses for which they Drainage Board have responsibility as the drainage authority.

Natural England will need to give their written assent Assent under for any works to be carried out within or affecting the Section 28 of River Wensum Site of Special Scientific Interest. The the Countryside Natural England proposals will be developed in partnership with and Rights of Natural England, and assent will be obtained prior to Way Act any works starting on the SSSI.

Consideration of Confirmation of the need for an assessment under need for Natural England Regulation 61 of the Conservation of Habitats and Habitats Species Regulations 2010 (Appropriate Assessment)

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Likely Organisation Comment Consent Regulations will be required from Natural England, due to the Assessment designation of the River Wensum as a Special Area of Conservation (SAC). It is anticipated at this stage that the works will be “directly connected with or necessary to the management of the site” and therefore detailed assessment under the regulations will not be required. This will be confirmed in writing with Natural England.

Natural England is actively working with the project team to assent the proposed works and ensure that the mitigation measures outlined below will not adversely affect protected species or their habitats. A consent letter from Natural England is needed before Protected any works can begin. species and Natural England Otters, water voles, bats and badgers are known to associated be present along the River Wensum. Since these are licences protected species, there will be a requirement to implement some mitigation measures as part of the proposed river restoration scheme. Consent from Natural England will be required to carry out mitigation activities if these require trapping or destructive search for water voles, for example.

Waste The requirement for a Waste Management Licence Management Environment Agency will be reviewed once detailed designs are available. Licence

Landowner Various landowners We need to continue liaison with key landowners. consents

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10. Project Risks

A number of key project risks may delay the delivery of the recommended option for Unit 51 and these include: 1. Uncertainty of availability of funding to implement recommended option.

2. Protected species survey and mitigation.

3. Inappropriate maintenance both prior to and post restoration.

4. Obtaining landowner consents to undertake enhancement works on private land, as well as

other permissions and consents (e.g. Flood Defence Consent).

5. Changes in UK or European environmental legislation.

6. Extreme weather conditions and / or flooding.

To manage these risks it is recommended that there is ongoing communication with key stakeholders including landowners, local planning authorities, NCC, internal Environment Agency functions, the Norfolk Rivers IDB, Natural England and the local communities within Unit 51 (Table 10.1).

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Table 10.1 – Key project risks that may delay the delivery of the recommended options for Unit 51 Risk Proposed Mitigation Level of risk Ongoing and open discussion with landowners and other stakeholders to inform them of the potential for Landowners not giving ecological improvements through enhancement permission for High works. Listen to landowners concerns and work enhancement works collaboratively to identify alternative methods or materials for proposed works. Availability of funding for Raise profile of project nationally and seek early High scheme identification of external sources of funds. Measures to prevent adverse impacts will be The need to mitigate and undertaken in accordance with the Environmental plan around protected Medium Good Practice Site Guide (Environment Agency, species 2005) and Planning Policy Statement 23. Work collaboratively with the Environment Agency Operations Delivery Team and the IDB to identify and Inappropriate maintenance agree an appropriate maintenance protocol within the Medium prior and post restoration context of the Targeted Maintenance option. Ensure that no inappropriate maintenance or other work is undertaken by riparian landowners. The cost of each restoration option will vary according to technical constraints such as access and scale of Uncertainty regarding costs Low project. Cost will need to be revised during the detailed design stage. Lack of forward momentum Ongoing consultations and discussions with the local to keep the scheme residents and key stakeholders. Provide regular Low progressing to achieve updates in the form of a newsletter. benefits in the river Change in UK or European Keep abreast of proposed changes in legislation so environmental legislation any changes in detailed design can be informed at an Low (e.g. fisheries legislation) early stage. Monitor weather conditions and ensure new and part built features are secured at the end of each working Extreme weather conditions day to prevent them being damaged by extreme Low and / or flooding weather or flood events. Allow contingency to cover the eventuality of adverse weather.

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11. Conclusions and Recommendations 11.1 Conclusions This report identifies river restoration options and measures that could be implemented to restore Unit 51 (North Elmham Mill to Elsing Mill) of the River Wensum Site of Special Scientific Interest (SSSI) to ‘unfavourable recovering’ or ‘favourable’ ecological condition and address WFD hydromorphological issues. Options have been identified that will deliver physical modifications to improve the ecological condition of the River Wensum. If river alterations are not delivered there remains a risk that the river will not be returned to ‘unfavourable recovering’ or ‘favourable’ ecological condition. Consideration has been given to terrestrial SSSI units on the functional floodplain where there is the prospect of improving any hydrological linkage with the river. Multi-Criteria Analysis A MCA was applied across a range of potential restoration options. This allowed options to be assessed individually and against each other in terms of technical, economic and environmental constraints or opportunities. The MCA is a powerful tool for appraising all options and associated measures in a consistent, replicable and transparent way. It can be used to identify those options that will move the SSSI unit towards ‘unfavourable recovering’ or ‘favourable’ ecological condition and those that do not. It also provides an indication of the relative importance of the options and their measures in achieving ‘unfavourable recovering’ or ‘favourable’ ecological condition for a particular reach. How those options and measures are applied to a reach is a case of professional judgement. The results of the MCA show that the recommended option for Unit 51 is a combination of major and minor in-channel restoration measures, including works to remove backwater effects e.g. the creation of a new bypass channel at Elsing Mill and weir removal at the site of Swanton Morley Mill. Costs The estimated cost of the recommended options for the unit is £412,000 (to the nearest thousand) which is less than previous estimates. This is partly a reflection of the restoration design philosophy used which is to provide features that the river cannot restore itself (i.e. back channels, and gravel glides) and to provide features that will ‘kick start’ a wider recovery process (i.e. deflectors, berms in key locations, channel re-sectioning and realignment). It is also a reflection of a detailed cost estimate exercise based on a more in-depth understanding of the restoration requirements for this unit. Environmental issues This feasibility report has also provided baseline data for a range of environmental criteria. This, and the information contained within Chapters 4 to 8, has allowed environmental issues to be scoped in or out of the environmental assessment that will be required to accompany the detailed design of restoration schemes. Consultation To date, consultation with key statutory and non-statutory stakeholders indicates good in-principle support for restoration of Unit 51.

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11.2 Recommendations To keep up the momentum for this project, the following recommendations are made: 1. To improve the likelihood of delivery of restoration schemes it is important that the project team continues to consult on a regular basis with key stakeholders, including, but not limited to:  Landowners  District and County Council planning authorities to determine the level of EIA required and any supporting planning consents  Internal Environment Agency functions  Natural England  Norfolk Rivers Internal Drainage Board. 2. ‘Targeted maintenance’ should be implemented as soon as possible to demonstrate a commitment to continued management of the river where this can be justified. This will also drive further action to implement the remaining recommended restoration options.

The environmental issues that have been scoped into the next stage of EIA should be considered as part of a best practice Environmental Report.

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12. References

1. @One Alliance (2007) River Wensum Aquatic Macrophyte Survey: AMP4 Water Resources Environment Programme: Habitats Directive Review of Consents. 2. Atkins (2009) River Wensum Restoration Strategy. Implementation River Unit 50 Bintree Mill to North Elmham Mill. Feasibility & Environmental Scoping Assessment. December 2009. Report to Eastern Area, Anglian Region, Environment Agency. 3. Atkins (2010) River Wensum Restoration Strategy, Mill Operating Protocol. Draft report to Eastern Area, Anglian Region, Environment Agency. 4. Babtie Brown & Root (2003) Upper River Wensum Strategy Study: Strategy Study Report. Report to Eastern Area, Anglian Region, Environment Agency. 5. Breckland District Council (2009) Adopted Core Strategy and Development Control Policies Development Plan Document. 6. Econ (1999) River rehabilitation feasibility study of the River Wensum (Norfolk)-Phase 2. Report to Eastern Area, Anglian Region, Environment Agency, Norwich, UK, 153pp. Perrow, M.R. & Newson, M.D. 7. English Nature (1993) Notification of SSSI Status: River Wensum, Norfolk. 8. Entec (2010) Habitats Directive Review of Consents - Stage 4 Options Appraisal: River Wensum SAC. Report for the Environment Agency. 9. Environment Agency (1995) River Corridor Survey of the River Wensum (Anglian Region, Eastern Area). 10. Environment Agency (1999) River Wensum Water Level Management Plan. Environment Agency (Anglian Region, Eastern Area). 11. Environment Agency (2003). Fry Distribution in the River Wensum. Interim Results and Observations from the 2003 Ecological Appraisal Programme. EA, Anglian Region, Eastern Area. Technical Note. 12. Environment Agency / Natural England (2004) The state of England’s chalk rivers: Summary report by the UK Biodiversity Action Plan Steering Group for Chalk River. [Online: http://www.freshwaterlife.org/servlet/BinaryDownloaderServlet?filename=1152695564918_chalk_ riv_summary_834762_1_.pdf. Accessed November 2009. 13. Environment Agency (2004) Crayfish Distribution in the River Wensum – Results & Observations from the 2003 Ecological Appraisal Fisheries Sampling Programme. EA, Anglian Region, Eastern Area. 14. Environment Agency (2007a) The River Wensum Water Level Management Plan. Report produced by Entec UK Ltd. 15. Environment Agency (2007b) Factors affecting roach Rutilus rutilus (L.) recruitment and survival in the River Wensum, Norfolk. EA, Anglian Region, Eastern Area. 16. Environment Agency (2009a) Position statement on hydropower. [Online: http://www.environment- agency.gov.uk/static/documents/Research/Hydropower_position_statement_FINAL_English.pdf. Accessed August 2009]. 17. Environment Agency (2009b) Good practice guidelines annex to the Environment Agency hydropower handbook: The environmental assessment of proposed low-head hydro power developments. [Online: http://www.environment- agency.gov.uk/static/documents/Business/Low_Head_Hydropower_August_2009.pdf. Accessed August 2009]. 18. Environment Agency (2009c) Water Resources GIS. October 2009 version. 19. Environment Agency (2010a) Web-based Flood Mapping: http://maps.environment- agency.gov.uk/wiyby/wiybyController?x=531500.0&y=181500.0&topic=floodmap&ep=map&scale =3&location=London,%20City%20of%20London&lang=_e&layerGroups=default&textonly=off

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20. Environment Agency (2010b). What’s in your backyard. [Online: http://www.environment- agency.gov.uk/homeandleisure/37811.aspx. Accessed August 2010]. 21. European Commission (2001) Guidance on EIA Scoping. Environmental Resources Management. 22. Gillian, S; Boyd, K; Hoistma, T and Kauffman, M (2005) Challenges in developing and implementing ecological standards for geomorphic river restoration projects: a practitioner’s response to Palmer et al. Journal of Applied Ecology. 23. Grieve, N.J., Clarke, S. & Caswell, B. (2002) Macrophyte Surveys of the River Wensum SAC. Centre for Aquatic Plant Management. 24. Halcrow (2008) Estimating costs of delivering the river restoration element of the SSSI PSA target. Final report prepared for the Environment Agency. 25. Heritage Gateway Website: http://www.heritagegateway.org.uk/gateway/advanced_search.aspx. 26. IEMA (2004) Guidelines for Environmental Impact Assessment. 27. JBA Consulting (November 2007) River Wensum Restoration Strategy, Supporting Technical Report for Natural England. 28. JNCC (2002) Standard Data Form DoE SPA, SCI and SAC: River Wensum. Version 2.1, Natura 2000 Data Form. 29. Land Use Consultants (2007) Breckland District Landscape Character Assessment. Final Report for Breckland District Council. 30. Mant, J. & Fellick, A. (2007) The River Wensum, Norfolk: An assessment of the current approaches to river restoration along the River Wensum and their potential to support chalk stream habitat requirements. A report to Natural England (prepared by the River Restoration Centre, Bedfordshire). 31. Multi-Agency Geographic Information for the Countryside (MAGIC) Website address: http://www.magic.gov.uk/. 32. National Biodiversity Network Gateway Website: http://www.nbn.org.uk/ 33. Natural England (2007) Conservation Objectives and definitions of favourable condition for designated features of interest: River Wensum SSSI. Consultation Draft, Norfolk and Suffolk Team. 34. Natural England (2010) SSSI Condition Assessment – River Wensum SSSI [Online: http://www.sssi.naturalengland.org.uk/Special/sssi/reportAction.cfm?report=sdrt13&category=S&r eference=1006328 Accessed January 2011). 35. Norfolk Rivers Internal Drainage Board (2007) Standard Maintenance Operations for rivers. 36. Rothera, S. (undated) Breckland Natural Area Profile. Report NA 46. Natural England. 37. Sear, D.A., Newson, M., Old, J & Hill, C. (2006) Geomorphological Appraisal of the River Wensum Special Area of Conservation. English Nature Research Reports, No 685, by GeoData, University of Southampton. 38. Stansfield, J., Adams, C., Whiting, C., Markwell, H. & Brown, R. (2001) River Wensum Invertebrate survey and ecological assessment 2001. Environment Agency, Fisheries, Recreation & Biodiversity: Ecological Appraisal Team, Ipswich. 39. Wensum Valley Project (1994) Wensum Valley Strategy, Norfolk. Produced by the Joint Advisory Panel of the Wensum Valley Project. 40. Wild Frontier Ecology Limited (2007) Water Vole Monitoring Report – River Wensum and Tributaries. River Wensum Mink Control Project. Report produced by John Harris for Norfolk County Council.

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Appendices

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Appendix A - Multi-Criteria Analysis Technical Note

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A.1 MCA Criteria & Options / Measures Feedback from the MCA workshop with the Environment Agency and Natural England confirms the need for greater clarification of the MCA process and in particular how the criteria and options/measures are defined. This technical note has been undertaken to address those queries. Within the criteria definitions, explanation is given of the 5 point scoring to which the weightings are applied. Typical scoring considerations for each criterion have been given to provide greater consistency of scoring. A.1.1 Criteria and criteria group definitions The criteria are divided into three major groups:  Ecology  Project Delivery  Technical. The ecology is the main driver for the project and so has to have the highest weighting, which is 1. The project objectives do not stand alone. Not only does the project have to succeed, but it must also be seen and felt to succeed. Therefore the aspirations of the stakeholders in the project also have to be recognized. This is nearly as important so the weighting for this is 0.9. To make a difference to the ecology the RWRS has to be implemented. An assessment of the choices implementation generates needs to be made. We have called this group technical criteria. There has to be a consideration of the practical delivery of the project in the real world as it is generally true that technical complexity generates cost, and impacts on quality and time. The weighting needs to be reasonably high, but not as high as the previous items, so 0.8 is used. Each of the three criteria groups is made up of a number of related criteria, which in turn have relative importance and hence need different weightings. These are explained by group. A.1.2 Ecology The primary objective of the project is to improve the ecology of the River Wensum. This falls into two parts: legally protected ecology and the rest. So, as a crude split the ecology needs to be divided into at least 2 sub groups. However, the legal protection is variable and progressive, with some species and habitats afforded greater protection than others. To demonstrate compliance with the law the criteria analysis needs to reflect the progressive nature of the legal protection. We have therefore divided the legally protected ecology into 3 sections to reflect the levels of importance:  International: SAC  National: SSSI  Regional: BAP. To this we add the non-protected ecology. This has to be included so as to satisfy the Environment Agency’s broader legal duty to consider and further conservation. This gives a fourth sub-group as follows:  Local: Contribution to overall ecology. In terms of RWRS these 4 items are not equal. The definitions and weightings are explored below.

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A.1.3 Compliance with National Designation: SSSI The primary drivers for the RWRS are the Defra PSA target based on SSSI condition (95% of SSSIs by area to be in favourable or unfavourable recovering condition by December 2010) and the requirement for the river to achieve ‘Good Ecological Potential’ under the Water Framework Directive. The SSSI covers the following: Table A.1 - SSSI designation targets

Statutory / Non Statutory Conservation Targets Drivers SSSI designation  Flow: Flow regime should be characteristic of the river. Levels of abstraction should not exceed the generic thresholds laid down for moderately sensitive SSSI rivers by national guidance.  Water quality: Biological GQA Class B; Chemical GQA Class B; No unnaturally high loads of suspended solids.  Phosphate: An annual average phosphate concentration of 0.05mg/l from the upstream limits of the SSSI to the confluence of the River Wensum with the White Water (the tributary that drains from East Dereham), and 0.1mg/l from that confluence to the downstream limit of the SSSI.  Siltation: No excessive siltation. Channels should contain characteristic levels of fine sediment for the river type.  Channel form: should be generally characteristic of river type, with predominantly unmodified planform and profile. Bank and riparian zone vegetation structure should be near-natural.

So from a project perspective the national protection has to have the highest weighting. Thus, it is allocated the highest weighting which is 1. With regard to scoring the following applies (Table A.2): Table A.2 - SSSI scoring

Compliance with National Designation: SSSI Score Description Typical Effect +2 High relevance Direct immediate improvement in designated item. +1 Low relevance Moving towards favourable condition. 0 Neutral No change. -1 Low Detriment Moving away from favourable condition. -2 High Detriment Permanent adverse changes.

A.1.4 Compliance with International Designation (SAC): The SAC covers the following:

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Table A.3 – SAC designation targets (Natural England, 2007)

Statutory / Non Statutory Conservation Targets Drivers SAC Designation The conservation objectives for the European interest features on the SSSI are:

to maintain*, in favourable condition, the:

 Watercourses of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation

to maintain*, in favourable condition, the habitats for the population of:

 Bullhead (Cottus gobio)  Brook lamprey (Lampetra planeri)  White-clawed crayfish (Austropotamobius pallipes)  Desmoulin’s whorl snail (Vertigo moulinsiana)

*maintenance implies restoration, if the feature is not in favourable condition.

PDFs of English Nature publications on the ecology and monitoring of the five European features can be downloaded from the publications catalogue on the Natural England website (www.naturalengland.org.uk).

The international protection must also rank highly, but from a project perspective, not as highly as the national importance; a weighting of 0.8 was used. With regard to scoring, Table A.4 outlines how SAC targets have been scored. Table A.4 –SAC scoring

Compliance with International Designation (SAC) Score Description Typical Effect +2 High relevance Direct immediate improvement in designated item. +1 Low relevance Moving towards favourable condition. 0 Neutral No change. -1 Low Detriment Moving away from favourable condition. -2 High Detriment Permanent adverse changes.

A.1.5 Compliance with Regional Designation (BAP): The biodiversity action plan most relevant to the River Wensum is the chalk rivers action plan. There are a number of additional species and habitat action plans that may be affected by river restoration on the Wensum. These are summarised in Table A.5. This criterion is also intended to cover protected species issues (e.g. those covered by the Wildlife and Countryside Act).

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Table A.5 – Biodiversity Action Plan targets

Statutory / Non Statutory Conservation Targets Drivers UK Biodiversity Action Plan The objectives of the UK National Chalk Rivers Habitat Action Plan are:

 Maintain the characteristic plants and animals of chalk rivers, including their winterbourne stretches.  Restore all rivers notified as SSSI to favourable condition.  Restore important non-SSSI rivers to favourable condition.

There are a large number of other national/Norfolk Habitat and Species Action Plans relevant to the Wensum, including floodplain and coastal grazing marsh, reed-bed, fen, otter, water vole, Desmoulin’s whorl snail, white-clawed crayfish and bat species. All these SAP/HAPs have targets and objectives (www.norfolkbiodiversity.org)

Bearing in mind that both the national and international importance will provide a good level of protection for BAP species and habitats, from a project perspective, this was not felt to be as important to the project, but still needed to be included, so the weight is correspondingly lower. The value of 0.6 was used. Table A.6 lists how UK BAP targets were scored. Table A.6 – UK Biodiversity Action Plan scoring

Compliance with Regional Designation (BAP) Score Description Typical Effect +2 High relevance Direct immediate improvement in designated item. +1 Low relevance Moving towards favourable condition. 0 Neutral No change. -1 Low Detriment Moving away from favourable condition. -2 High Detriment Permanent adverse changes.

A.1.6 Contribution to overall ecology: The non-protected ecology needs to be included to address the Agency’s duty to further conservation. Table A.7 lists those issues/drivers that have been identified as being important to improving overall ecology in the Wensum.

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Table A.7 – Issues identified in this study as being important drivers for restoration

Statutory / Non Statutory Conservation Targets Drivers North Norfolk Natural  Identify and promote flows necessary to sustain Area Profile geomorphological and ecological interest of the system.

 Identify, maintain, enhance, and restore both natural and man- made riverine features which provide ecological and conservation interest.  Ensure protection, enhancement and restoration of habitat features during the design and implementation of flood defence schemes.  Restore arable land adjacent to rivers back to pasture to reduce silt loading and improve habitats.  Manage associated dyke systems on a regular but not intensive regime. Breckland Landscape  Conserve the tranquil, pastoral, undeveloped character of the Character Assessment River Wensum and Black Water.  To manage and, where appropriate, increase natural floodplain habitats such as grasslands, reedbeds, watermeadows and grazing marsh as well as areas of heathland associate with the commons.  Wooded lanes of the valley sides should be conserved to create a sense of enclosure and ensure historic character is maintained.  Maintain predominantly grazed pastoral valley floor, avoid extension of arable cultivation down the valley sides.  Seek to conserve the water levels and water quality in the river and associated ditches.  Maintain areas of alder/osier carr at their current extent and seek to plant wet woodland species after mineral extraction. Environment Agency  To sustain and where appropriate enhance or restore the habitat diversity within the water environment.  To provide an environmental assessment and recommendations to ensure the maintenance and enhancement of conservation interest to flood defence.  Develop Water Level Management Plans to protect the ecology of sensitive wetlands.  Fisheries Action Plan for the Wensum. European Water  Take appropriate measures to ensure water bodies attain Framework Directive Good Ecological Potential by 2027.

 Establish a Programme of Measures to ensure water bodies attain Good Ecological Potential/Status. European Habitats  Monitor, assess and enhance favourable condition of SAC Directive rivers.

 Review of consents under Regulation 50 of the Habitats Regulations is another major driver for the Environment Agency and other competent authorities.

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Statutory / Non Statutory Conservation Targets Drivers UK Gov Public Service  95% of SSSIs by area in favourable or unfavourable Agreement (PSA) recovering condition by December 2010. Targets

Planning Policy  PPS9 sets out the Government’s national policies on Statement 9: protection of biodiversity and geological conservation through Biodiversity and the planning system. Geological Conservation  Plan policies on the form and location of development should take a strategic approach to the conservation, enhancement and restoration of biodiversity and geology. Environmental Higher Level Stewardship applications for environmentally Stewardship Targeting - sensitive farming practice: Mid Norfolk  Maintain or enhance Sites of Special Scientific Interest (SSSIs).  Improvement of water quality through reduction of soil erosion (priority: R. Wensum catchment) and leaching of nutrients.  Conservation of landscape and wildlife associated with arable farming; in particular maintaining locally distinctive landscapes and reversing the decline in farmland birds.  Protection of historic and archaeological sites.  Access – provide further recreational facilities, to promote greater appreciation of the countryside.  Maintenance and restoration of BAP priority habitats.  Conservation of BAP priority and locally important species.

However, again from a project perspective this is not as important so is weighted lower at 0.5. Scoring of this criterion is shown in Table A.8. Table A.8 – Contribution to overall ecology scoring

Contribution to Overall Ecology Score Description Typical Effect +2 High relevance Direct immediate improvement in designated item. +1 Low relevance Moving towards favourable condition. 0 Neutral No change. -1 Low Detriment Moving away from favourable condition. -2 High Detriment Permanent adverse changes.

A.1.7 Project delivery To deliver the project the RWRS objectives need to be met, and the stakeholders they impact on need to support and promote those objectives. Thus, the criteria within this group can be subdivided into:  RWRS objectives  Stakeholders. The stakeholders for this project naturally fall into 2 groups: Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 140

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 Statutory stakeholders, and  Non-statutory stakeholders. The definition of statutory stakeholders is straight forward: it is those statutory bodies that are either funding the works or have a legal right to control the outcomes (for example: Environment Agency). Non-statutory stakeholders are those outside of the government bodies who have a legal right to comment and so influence the outcomes (for example: land owners). The outcomes of the RWRS do not stand in isolation because besides impacting on the people in the valley they impact on the wider environment and its use. This is the non ecological environment of the valley which is predominantly of interest to people, so we have termed it:  Human Environment. This gives 4 sub-criteria, and again, in terms of the RWRS these are not equal. The definitions and weightings are explored below. A.1.8 Compliance with strategy objectives This whole project is about delivering the objectives of the RWRS. This comprises of 2 parts:  The general objectives of the project, as covered in the RWRS Recommendations.  The specific restoration measures for individual reaches as covered in RWRS Appendix A. Clearly this is the most important criterion and so has to have the maximum weighting of 1. Scoring of this criterion is shown in Table A.9. Table A.9 – Compliance with strategy objective scoring

Contribution to Overall Ecology Score Description Typical Effect Immediate and/or full delivery of easily identified +2 High relevance RWRS objective. Enabling or partial delivery of identifiable RWRS +1 Low relevance objective. 0 Neutral No change. Temporary or low level interference with RWRS -1 Low Detriment objective. Immediate and/or full interference of easily identified -2 High Detriment RWRS objective.

A.1.9 Compliance with statutory stakeholders This covers the views of those statutory bodies that have a legal and/or financial stake in the success of the project. In probable order of priority, this includes:  Environment Agency  Natural England  Norfolk Rivers IDB  Local authority  Norfolk CC  English Heritage. For the project to be supported to fruition, with the objectives carried forward into the future, the statutory stakeholders will have to feel that the project is a success. This will have to consider views from the wider organisation where there is consultation. Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 141

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Without the support of the statutory bodies the full delivery of RWRS reach objectives will be difficult. This is nearly as important as compliance with the RWRS itself, and so has a weighting of 0.9. Scoring of this criterion is shown in Table A.10.

Table A.10 – Stakeholder scoring

Compliance with Statutory Stakeholders Score Description Typical Effect +2 High relevance Large majority with favourable view. +1 Low relevance Small majority with favourable view. 0 Neutral No issues. -1 Low Detriment Small majority with concerns. -2 High Detriment Large majority with concerns.

A.1.10 Agreement with non-statutory stakeholders Non-statutory stakeholders are those outside of the government bodies who have a legal right to comment and so influence the outcomes. This covers, in probable order of importance:  Land owners  Agricultural tenants  Fishery tenants  Householders  Commercial interests. Although the statutory bodies have the ability to impose some aspects of the strategy on the valley, without support of those who own or occupy the land and river the process of implementation would be:  Slow and expensive, due to legal process.  Lacking in richness due to lack of local knowledge informing designs.  Viewed as a failure and so lack long term viability.  Impact on long term relationships with the statutory bodies in everything they do. This is of importance to the project delivery and so is weighted at 0.9. Scoring of this criterion is shown in Table A.11.

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Table A.11 – Non-statutory stakeholder scoring

Compliance with Non-statutory Stakeholders Score Description Typical Effect +2 High relevance Large majority with favourable view. +1 Low relevance Small majority with favourable view. 0 Neutral No issues. -1 Low Detriment Small majority with concerns. -2 High Detriment Large majority with concerns.

A.1.11 Contribution to human environment This covers both non-river statutory designations such as:  Archaeology  Town & Country Planning as well as human usage of the river and valley such as:  Angling  Canoeing  Walking & footpaths  Landscape and wider amenity. Although this is the non ecological environment of the valley, it is predominantly of interest to people, so it must be included in the criteria. It is important, but not central to the delivery of the project and so has been given a weighting of 0.4. Scoring of this criterion is shown in Table A.12. Table A.12 – Human environment scoring

Human Environment Score Description Typical Effect +2 High relevance Widespread support. +1 Low relevance Some support. 0 Neutral Indifferent. Some general concern or local concern about small -1 Low Detriment issue. Wide scale concern or strong concern over specific -2 High Detriment local issue.

A.1.12 Technical This criteria group concentrates on the delivery of the RWRS objectives. It is broken down into 4 sub-criteria areas:  Technical feasibility & practicality  Geomorphic form & function  Flood risk  Climate change & sustainability. Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 143

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Each of these deals with particular risks that will vary by reach and by the selected restoration solutions applied at particular locations.

A.1.13 Technical feasibility & practicality This item covers:  Feasibility assessment  Engineering design  Construction process  Commercial risk  Maintenance liabilities.

This is the most important aspect regarding the management of risk in the project, and so is an important technical factor within the technical criteria group. A weighting of 1 has been used. Scoring of this criterion applies and is shown in Table A.13. Table A.13 – Technical scoring

Technical Feasibility & Practicality Score Description Typical Effect +2 High relevance Large benefit with little risk. +1 Low relevance Small overall benefit or lack of difficulty 0 Neutral Average. -1 Low Detriment Some difficulty. -2 High Detriment Little benefit with large risk.

A.1.14 Geomorphic form & function The shape of the river and the flow processes are important for 2 reasons:  The environmental designations specifically mention them, and  It is necessary to understand the processes and the resulting river shape to be able to design any of the restoration options/measures to produce predictable results that sustain into the future. This is therefore important regarding the management of risk in the project, and so has to be an important technical factor within the technical criteria group. A weighting of 1 has been used. Scoring of this criterion is shown in Table A.14. Table A.14 – Geomorphic scoring

Geomorphic Form & Function Score Description Typical Effect Immediately delivers full form and/or mature +2 High relevance processes. +1 Low relevance Kick starts process or provides some form. 0 Neutral No change.

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Geomorphic Form & Function Reinforces existing lack of processing at a local -1 Low Detriment scale. Reinforces existing lack of processing or creates -2 High Detriment inappropriate processing anywhere.

A.1.15 Flood risk Flood risk management is one of the Environment Agency’s primary responsibilities, therefore project outcomes cannot increase flood risk to people or properties. This is particularly important on the Wensum as there are 44 properties at risk of flooding, and there are routine maintenance activities to control existing flood risk. Any proposals that impact on water level or flow on statutory Main River require Flood Defence Consent from the Environment Agency, the primary objective of which is to demonstrate no detrimental effects on flood risk. This is a significant factor within the technical criteria group and so has a weighting of 1. Scoring of this criterion is shown in Table A.15. Table A.15 - Flood risk scoring

Flood Risk Score Description Typical Effect +2 High relevance Good risk reduction locally and/or elsewhere. +1 Low relevance Some reduction in flood risk anywhere. 0 Neutral No change. -1 Low Detriment Some increase in flood risk anywhere. -2 High Detriment Significant increase in local flood risk.

A.1.16 Climate change & sustainability This has been included to ensure that project proposals remain fit for purpose into the future. Current UK guidance on the impacts of climate change on fluvial flooding from the government’s Foresight Report, which has fed into Planning Policy Supplement Note 25 (PPS 25), recommends that an allowance of an extra peak flow of 20% is made, which covers the impact on flood risk change to 2050. Project proposals are viewed against their ability to withstand increased flows without detriment to themselves, the habitat created by them, or flood risk. Clearly a lack of robustness is not very sustainable in its own right. However, given wider concerns, a view on the carbon footprint of proposals is also appropriate. Whilst it is a useful criterion it is not the most important, so a weighting of 0.8 is used. Scoring of this criterion is shown in Table A.16.

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Table A.16 – Climate change scoring

Climate Change & Sustainability Score Description Typical Effect +2 High relevance Is stable in the short and long term. Is stable in the short term or provides a pre-cursor to +1 Low relevance later works. 0 Neutral No change. -1 Low Detriment Is unstable in the short term or prevents later works. -2 High Detriment Is unstable in the short and long term.

A.1.17 MCA options 6 major option groups have been identified:  Do nothing  Do minimum  Targeted maintenance  Continue as present  River restoration  Alternative options. These are in rough order of increasing intervention with the natural processes. They are briefly described below:

A.1.18 Do nothing As the objective of the strategy is to improve the ecology of the river, which is predicated on the return of natural form and process, this option means:  No maintenance to main river or IDB channels  No restoration to any channels or floodplain  No operational activity A.1.19 Do minimum This is from the view of the RWRS and so means:  Opportunistic restoration, eg. o Securing fallen trees as LWD, o Re-shaping shoals where growth occurs after floods o Re-shaping bank profiles to create berms when bank collapse occurs  No maintenance  No operational activity A.1.20 Targeted maintenance This covers:  Reduced maintenance: reactive in selected critical areas. Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 146

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 Mitigation for activity in form of small scale restoration.  Operational activity; sluice management for high flows. A.1.21 Continue as present This covers existing arrangements:  Planned maintenance: assessed LWD & CWD removal; selected weed cutting and silt removal.  Opportunistic small scale restoration.  Operational activity: sluice management for high flows. A.1.22 River restoration This covers 20 different restoration measures that have been identified for the river. Each of these is assessed for its use on the particular reach being scored. A.1.23 Alternative options There are 3 options that have been considered:  Increased main river maintenance. This includes: - Increased in-channel clearance of silt. - Increased frequency of weed cutting. - Return of channel to “design” dimensions. - Maintained timber clearance. - Bank repairs.  Increased main river and IDB channels maintenance. This includes: - As above, plus, - Integrated programme for main river and IDB channels. - Inclusion of IDB channel main river confluences for regular maintenance.  Mills re-use for hydro-power. This includes: - Overall generation of energy through harnessing the kinetic energy of water. - Operational reinstatement of all water level control structures. - Operating protocols for all structures. - Regular channel maintenance around control structures. These options were derived from comments picked up at the ‘drop in’ sessions and represent broad aspirations.

A.2 Use of MCA Scorings The use of MCA and the resultant reach scores represents a key part of the design process. The overall process is shown in Table A.17 as follows:

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Table - A.17 - SSSI Designation targets

A Constructing the MCA Tool 1 Identification of options/measures. 2 Selection of success criteria. 3 Ranking of success criteria using weightings. 4 Setting up the MCA table. B Applying the MCA Tool (Spreadsheet) to Specific Reaches 1 Is the option/measure applicable to the reach? If no, discard. 2 Work through each criterion by option/measure. 3 Apply weighting and determine total weighted score (TWS) 4 Discard all options/measures with zero or negative scores. 5 Mill structure measures: Apply the best scoring measure. Other measures: Undertake statistical analysis and discard measures scoring 6 below lower limit. Other measures: Apply remaining measures in order of highest to lowest 7 scoring. 8 Gravel works: Apply best scoring measure.

A.2.1 Note on statistical approach The options need to be checked for importance to see which ones are truly important and which ones are not. This has been determined by calculating which options have a TWS outside of one standard deviation either side of the mean. This was chosen as it is a standard measure of dispersion. Those with a value greater than the sum of the mean plus the standard deviation are of high importance: those with a value less than the sum of the mean minus the standard deviation are of low importance. Those of low importance represent those options that could easily turn negative were only a few criteria to get more harshly re-appraised: those of high importance are those that are very robust, and so represent the minimum options that should be carried out on any reach.

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Appendix B - Costings

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B.1 COST DETAILS To generate the cost estimate for Unit 51, a certain number of assumptions have been made:  General assumptions that apply to all measures.  Specific assumptions that apply to particular measures. B.1.1 General assumptions The following costs have not been taken into account: 1. Significant works to address site access issues (haul roads, tracks etc). 2. Works relating to unforeseen ground conditions and ground investigation costs. 3. Allowances for landowner compensation or accommodation works. 4. Phase I habitat surveys and ecological mitigation works. 5. Utility searches. 6. Contractors general Items/Insurances. 7. Detailed design. 8. Permissions, consents and consultation related costs. 9. Project specific risks. 10. Costs have not been inflated using latest price indices but are believed to be representative of current market conditions. The cost estimates has been derived using assumptions appropriate for the level of detail necessary for concept design. These estimates allow comparison of costs between other conceptual designs undertaken for individual river units. B.1.2 Specific Assumptions Fencing Fencing costs are summarised in Table B.1 below. The following assumptions apply: 1. The fencing used is assumed to be simple livestock fencing: - 100mm diameter tanalized timber posts driven at 3m centres, - 3 barbed wires at 1.2m, 0.8m and 0.4m. 2. Fencing lengths vary depending on the Reach. Fencing is installed where necessary to protect the river edge from poaching that could be caused by grazing. This is to satisfy landowner requirements and bank protection needs.

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Table - B.1 - Total estimated costs for fencing creation for Unit 51

Reach Reach Length Assumed Fencing Length (m) (m) 14 (all) 4830 4830 15 2520 2520 16 1170 1170 Total Length: 8520 Rate for supply and installation £/m 8 Cost for unit: £68,160

Berm creation Berm costs are summarised in Table B.2 below. The following assumptions apply: 1. Low level berms will be constructed below 1/2 bank height, on the inside of existing bends, to increase sinuosity of the channel. 2. A total of 35 berms are recommended for indicated on Figures 6.2 to 6.6. 3. Construction activities consist of removing vegetation for re-use; staking the new alignment with hardwood posts at 0.75m centres; placing double height coir rolls against the stakes; backfilling with local material to blend height to local berm heights; replace vegetation. 4. The bioengineering revetment is to be cut back into the existing bank material to stop outflanking. This will require an overall length of 1/3 of berm lengths.

Table - B.2 Total estimated costs for berm creation for Unit 51

Reach No. Bends Bermed Berm Length (m) Total Length (m)

14a 6 36.6 219.6 14b 17 36.6 622.2 14c 5 36.6 183 15 3 36.6 109.8 16 4 29.7 118.8 Unit total (m) 1253.4 Rate (£/m) 90 Cost for unit: £112,806

Channel re-sectioning Channel re-sectioning costs are summarised in Table B.3 below. The following assumptions apply: 1. Re-sectioning is recommended for two reaches, 15 and 16, totalling 183m and 171m in length respectively. 2. Re-sectioning assumes simple excavation work to the upper bank. 3. Depth of excavation will depend on local conditions, but should not be lower than existing self-formed berms; otherwise it will cause instability under flood flows as it will expose the

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softer material at the landward end of the berm. For the purpose of the cost estimates, 1/2 channel height has been assumed. 4. The river edge vegetation is to be retained for re-use on the berm, and bank top vegetation and topsoil re-used on the rear slope of the berm to provide protection. 5. Rear slope to the berm to be at a self-stable angle of recline, and certainly no steeper than 1:2. 6. Width of the berm will depend on local conditions, but does not need to be wider than ½ existing channel top width from hard bank edge to middle of rear slope. 7. Length of berm along the river will depend on local conditions; primarily the proximity of other features. 8. It is assumed that arisings will be transported and spread within 100m of the works, and outside of the floodplain. 9. The arisings have the potential to be used in the construction of other features.

Table B.3 - Total estimated costs for excavation associated with re-sectioning for Unit 51

Reach Length Channel Nom. Channel Nom. Nom. (m) top width Width Depth Depth Volume (m) (m) (m) (m) (m3) 14 (all) 0 n/a 15 183 8.1 4.05 1.69 0.64 474.3 16 171 6.5 3.25 1.16 0.58 322.3 Unit volume: (m3) 796.6 Excavation: reduce level <1m (Rate:£/m3) 9.83 Dispose spoil 100m from excavation (Rate:£/m3) 4.35 Cost for unit: £11,297

Tree felling Tree felling costs are summarised in Table B.4 below. The following assumptions apply: 1. Qualified arborists can typically trim, control and fell 4 riverside trees (approximately 50 years old) over 50m of river, in a day. 2. Tree felling is required along the banks of 285m of river. 3. Cost per day for a team of two qualified arborists to trim, control fell is assumed to be £500. This assumes 4 trees (approximately 50 years old) over a distance of 50m can be felled in one day. Costs include cording the wood for log piles, or trimming and cutting trunks for re-use. Costs do not include any transport or movement of timber once felled. Tree felling costs are taken as £10/m of river.

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Table B.4 - Total estimated costs associated with tree felling for Unit 51

Reach Length (m) 14a 0 14b 155

14c 0 15 0 16 130

Length in unit: 285 Rate: (£/m) 10 Cost for unit: £2,850

Backchannel reconnection Backchannel reconnection costs are summarised in Table B.5 below. The following assumptions apply: 1. Backchannel reconnection assumes simple excavation to connect existing channels with the river excavating a total of 1295m with no bank or bed protection. 2. To provide an appropriate size of channel, and stable bank profile, it has been assumed that the bed width of the excavation will be equivalent to river height, and the top width will be 3 times the river height. This will provide 1:1 side slopes, which matches natural bank angles. 3. Backchannel reconnection works would also need to include appropriate works to re-form the backchannel to enhance stability and habitat delivery. Typically this could consist of re-sectioning and removing encroaching silt and vegetation within the channel. 4. Reconnection at the downstream end will be excavation down to river bed level; reconnection at the upstream end will be by excavation down to the backchannel bed level, post any clearance / re-forming works. 5. Bank protection works beyond re-placing vegetation turfs are not taken into account in the rates. Any further works will be dependent on local conditions found during detailed design investigations.

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Table B.5 - Total estimated costs associated with backchannel reconnection for Unit 51 Reach Exc. Length River Depth Nom. Volume Cost (£) (m) (m) Section (m3) (m2) 14a 290 1.29 6.84 1984 28,127 14b 390 1.29 6.84 2668 37,827

14c 115 1.29 6.84 787 11,154 15 450 1.28 5.15 2318 32,862 16 50 1.16 4.85 243 3,439

Unit rate of excavation (£/m3) 9.83 Dispose spoil 100m from excavation (Rate:£/m3) 4.35

Cost for unit: £113,409

Gravel glides Gravel glide costs are summarised in Table B.6 below. The following assumptions apply: 1. Cost is directly dependant on volume placed. 2. Gravel glides dimensions vary according to location as indicated in the Table B.6 below. 3. Gravel glides have been dimensioned using channel size dimensions provided in the 2007 JBA report. Width of channel used has been taken as the ‘erodible bank width’ as it is representative of the realistic width of erosion, and therefore needs protection. 4. The depth of gravel used is the amount identified as needed to raise the bed. 5. The length of the glide is taken as 3 times the resistant bank width to ensure that ‘edge effects’ are controlled, so that these artificial glides more closely match those observed, and will realistically fit between the existing bends. 6. The long section through the glide assumes a 1:1 slope at the upstream and downstream ends to give some stability. This has been allowed for in the volume per glide. 7. The rate for supply and placement of gravel is based on a material supply cost of £27/tonne for 20-50mm gravel rejects and a placement cost of £4.85/m3. At 1.78t/m3 the gravel supply rate equates to £48.06/m3, which combined with the placement rate gives an overall rate of £53/m3.

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Table B.6 Total estimated costs associated with installing gravel glides for Unit 51

Reach Bed Erodible Resistant Length Volume Number Volume Raising width Width (R) 3 x R (m) per glide of Glides per Required (m) (m) Reach (m) (m3) 14a 5 1.36 12.2 8.1 24.3 426 2130 14b 0 n/a 14c 3 0.5 4.58 3 9 22 66

15 15 0.6 12.2 8.1 24.3 182 2730 16 7 0.71 9.9 6.5 19.5 142 994 Volume for unit: (m3) 5920 Rate for supply (£/m3) 53

Cost for unit: £313,760 Note: Glides in Sub-reach 14c sized to realignment dimensions.

Channel realignment: Channel realignment costs are summarised in B.7 below. The following assumptions apply: 1. Excavation will be to the full height of the riverbank from bank top to river bed; unlike re- sectioning which is 1/2 height excavation. 2. Unlike other excavation based measures, the spoil arisings from this operation are assumed to be re-used locally to in-fill the channel from the far bank. 3. Realignment assumes the bank is realigned by the equivalent of a natural channel width. It is also assumed that the bank is cut at a stable angle of recline, and that no protection works are carried out to allow natural processes to prevail. 4. Channel realignment is recommended at one Reach 14c for a total length of 350m.

Table B.7 - Total estimated costs associated with channel realignment for Unit 51

Reach No. Length Channel Volume Rate Cost (£) Locations per Area (m2) (m3) (£/m3) Location (m) 14a 0 n/a 14b 0 n/a 14c 1 350 4.24 1485 9.83 14,602 15 0 n/a 16 0 n/a Cost for unit: £14,602

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Deflector Deflector costs are summarised in Table B.8 below. The following assumptions apply: 1. It is assumed that these are created from large woody debris (LWD) won locally and where possible from tree felling activities. 2. A deflector group consists of three deflectors pointing upstream; spaced at a natural channel width along the bank to affect an area equivalent to three times natural channel width. The length of the deflector is determined locally so as to mobilize silts and suit channel width. 3. The deflectors consist of clean timber tree trunks alternately staked and wired to hardwood stakes at 1m centres. The butt end is embedded into the bank by 2m or one third length whichever is the shortest. The trunks are to be laid on shorter faggot bedding. 4. Deflector height to be no higher than high summer water level so that it can drown out under higher flows. 5. Deflectors are recommended for 10 locations in this unit (two in Reach 14 and eight in Reach 16).

Table B.8 - Total estimated costs associated with implementing deflectors for Unit 51

Reach No. of Groups Length per Reach (m) 14a 1 49 14b 0 n/a

14c 1 49 15 0 n/a 16 8 156 Total length for unit (m): 254 Rate per length of river (£/m) 44

Cost for unit: £11,176

Tree planting Tree planting costs are summarised in Table B.9 below. The following assumptions apply:

1. Tree species are assumed to be appropriate native riverside species such as: alder, black poplar, and willow. The black poplar needs to be from a certified source (and of Norfolk provenance) as they hybridize readily. 2. Tree planting consists of a group of 10 individual trees at specific locations to create shade and bank reinforcement. Tree group planting is recommended in 28 locations. Planting areas to run on average for 10m along the bank length. 3. Planting costs include: supply of 2-3m standard; planting; tube, stake and tie and deer proof enclosure. Total estimated cost per tree is £58.

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4. Cost for planting a tree is estimated on team of two (£500/day) capable of planting 3 trees per hour over 7 hours. 5. An allowance for machinery access to control density of shading is required. It is suggested that a minimum of 4m distance is maintained between the fence line and the trees.

Table B.9 - Estimated tree costs

Item Cost (£) Supply 2-3m standard tree £10 Plant tree £23 Supply & install: tube, stake, ties £1

Deer proof enclosure £24 Total per tree: £58

Table B.10 - Estimated costs for new tree planting for Unit 51

Reach No. of Locations No. of Trees 14a 4 40 14b 5 50 14c 4 40 15 0 n/a 16 15 150 Total: 280 Rate (£/unit) 58

Cost for unit: £16,240

Plugs in main channel Plugs construction costs are summarised in Table B.11 below. The following assumptions apply: 1. Plugs are constructed using gravel rejects. 2. Upstream and downstream slopes are constructed at a 1:1 slope. 3. The height of the plug assumes current channel depth. 4. The width of the plug is based on JBA’s 2007 estimated channel depths and estimated channel sizes following site visits.

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Table B.11 - Estimated costs for plugs for Unit 51

Reach No. Channel Depth Nominal Length Nominal Cost (£) Plugs Width (m) Section of Plug Volume 3 (m) (m2) (m) (m ) 14a 1 15 2.46 36.9 15 553.5 29,336 14b 0 n/a

14c 1 15 2.46 36.9 15 553.5 29,336 15 0 n/a 16 0 n/a

Rate (£/m3) 53 Cost for unit: £58,672

Other restoration measures Other restoration measures in Unit 51 refer to lowering spoil embankments. The embankments will be lowered by removing excess material using appropriate machinery. Volumes of earth to be removed have been estimated following indicative measurements taken during the site visits based on a rate of £9.83/m3. Costs for embankment lowering works are summarised in Table B.12. Table B.12 - Estimated costs for lowering embankments in Unit 51

Reach No. Total Excavation Total Volume Cost (£) Locations Length Area (m2) (m3) (m) 14 (all) 4 250 1.5 375 3,686 15 3 355 0.8 284 2,792 16 1 160 0.8 128 1,258 Rate (£/m3) 9.83

Cost for unit: £7,736

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B.1.3 Summary costs for recommended restoration measures for Unit 51 Table B.13 - Estimated costs per measure

Measure Description Quantity* Rate (£) Cost (£) 5.1 Fencing (m) 8,520 8 68,160

5.16 Berm creation (m) 1,253 90 112,806 5.15 Channel re-sectioning (m3) 797 14.18 11,297 5.12 Tree felling (m) 285 10 2,850

Backchannel – 5.17 7,998 14.18 113,409 reconnection (m3) 5.7g Gravel glides (m3) 5920 53 313,760 5.19 Channel realignment (m3) 1485 9.83 14,602 5.13 Deflector (m) 254 44 11,176

5.11 Tree planting (unit) 280 58 16,240 Other Plugs (m3) 1107 53 58,672 Other Embankment lowering (m3) 787 9.83 7,736 Option G3 Targeted maintenance - Unknown -

Cost for unit: £730,708 Note: Quantity values rounded to nearest whole number so costs contains rounding errors.

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Appendix C – Ecology tables

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C.1 River Wensum SSSI/SAC: Status, ecology and habitat requirements of European interest features

Species / community Designations and status General ecology Habitat requirements Habitat requirements (continued)

Brook lamprey Listed in annexes IIa and Va of the Habitats Brook lamprey have both a sedentary larval Ammocoete larvae Adult lamprey (Lampetra planeri) Directive, Appendix III of the Bern (ammocoete) stage and an adult dispersal Substrate Adult spawning grounds Convention, and as a Long List Species in phase, during which spawning takes place. Ammocoetes occur in suitable silt beds, mainly in running water but Spawning grounds are located in areas of the UK Biodiversity Action Plan. They do not feed as adults and hence spawning sometimes in large numbers in silt banks in lakes. Preferred small stones and gravel in flowing water, is generally considered to be preceded by a substrate varies in depth from a few cm to 30 cm and is generally with spawning often occurring at lower The most common of the three British relatively short migration to the spawning areas. composed of mud, silt, or silt and sand with a high organic content ends of pools. The spawning gravels are lampreys, occurring over much of the Brook lamprey tend to undertake small upstream (optimum particle size 80–380 μm). Larval nursery beds are often composed of stones up to 3 in. with good British Isles. Absent from much of Scotland migrations prior to spawning during which time located at the edges of streams and rivers, well away from the main permeability, although smaller north of the Great Glen. they continue to burrow like ammocoetes or hide current in flowing backwater sections. consolidating particles are required. under stones during the day. The extent of the Stones embedded in fine sands or silts migration depends on stream gradient which Water quantity and quality which form a hard bed are often avoided. may also impact upon the distance ammocoetes Flow rates of 0.5 m s-1 at the water surface, and 0.4 m s-1 at a The nest, which may be constructed by up drift downstream during development, as well as depth of 25 cm have been observed above nursery beds and flows to a dozen or more adults, is normally an spawning habitat availability. After spawning has of 8–10 cm s-1 have been recorded over Lampetra burrows. oval depression about 20–40 cm across occurred, newly hatched larvae leave the nest and 2–10 cm deep. and distribute themselves by drifting Water quantity and quality downstream and burrowing in suitable areas of The brook lamprey is regarded as being silty sand. sensitive to pollution requiring at least UK Water Quality Class B (EA classification) Life-cycle in all parts of any river where brook Metamorphosis July to September lamprey life stages occur. At spawning Spawning migration November to February sites flow velocities of 30–50 cm s-1 have Spawning March to April (10-11oC) been noted. Bullhead (Cottus In the UK the native range of Cottus gobio Common species of the headwaters of many Bullhead habitat requirements are dependent on life stages. Coarse Substrate gobio) is restricted to England and Wales, types of upland and lowland river where it is benthic substrates with large stones are required for breeding and Benthic gravel and stones substrates are although some introduced populations are associated with stony benthic habitats with shallow riffles and glides are utilised by YOY (young of year) fish. a vital habitat requirement for bullheads established in Scotland. moderate flow. Also occasionally found in lakes. Adults appear to prefer sheltered sections created by woody debris, as they provide both spawning habitats Listed in annexes IIa and Va of the Habitats Benthic macroinvertebrates such as Gammarus tree roots, leaf litter, macrophyte cover or large stones and all life and refuges against flow and predators. Directive, Appendix III of the Bern and Asellus, together with aquatic fly larvae are stages require slack-water refuges during spate flows. Bullheads will also utilise macrophytes as Convention. the dominant prey items. Habitat H3260 ‘Rivers refuges from predators and flows if large with Ranunculion fluitantis and Callitricho- Water quantity stones are a limiting factor. If gravel and batrachion vegetation’ is a key habitat for this Water depth is not critical providing it is >5 cm and flow is stone substrates are not limiting within the species in the UK. adequate. High temperatures or low dissolved oxygen may be fatal stream, bullheads will also associate with in shallow water, because temperature fluctuations are greater. depositional habitats such as pools Spawning occurs from February to July with the Typically, bullhead are found in depths of 20 to 40cm. containing woody debris. male excavating a nest under a suitable large stone to attract a female. Bullheads may use Water quality Channel structure other media such as woody debris or tree roots. Some tolerance to organic pollution (ammonia) and heavy metals is Natural channel forms exhibiting riffle/pool The female lays a batch of up to 400 eggs (2– exhibited where oxygen saturation remains high. The bullhead’s sequences provide appropriate substrate 2.5 mm in diameter), which adhere to the sympatric occurrence with brown trout indicates a requirement for and flow character for bullhead, as a underside of the stone. The male defends the oxygen concentration of 40% saturation and critical thermal limits of result supporting higher densities than brood against predators and maintains water – 4.2 and 27.7°C have been described. heavily modified channels. circulation by fanning the eggs. Eggs hatch after Filamentous algal growth resulting from eutrophication is Riparian trees are known to provide 20 to 30 days and after 10 days the fry (9 mm in detrimental where algae cover the favoured coarse, hard substrate shade and shelter as well as valuable length) disperse, colonising newly available (see below) and influence food-web dynamics. input of woody debris and leaf litter. habitat downstream including temporary channels, and floodplain lakes.

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Species / community Designations and status General ecology Habitat requirements Habitat requirements (continued)

Desmoulin’s whorl Desmoulin’s whorl snail is listed under Desmoulin’s whorl snail lives in permanently Water level requirements snail (Vertigo Annex II of the European Union Habitats wet, usually calcareous, swamps, fens and Hydrology is a factor determining the distribution of the Desmoulin’s moulinsiana) and Species Directive. It is a priority marshes, bordering rivers, lakes and ponds, or whorl snail with high groundwater levels throughout the year being species in the UK Biodiversity Action Plan in river floodplains. It is most often found in open one of the most important factors. Maximum snail densities are (HMSO 1996) and is listed in the British situations associated with the following often located where water levels are continuously above the ground Red Data Book (Bratton 1991) as an RDB3 vegetation: surface throughout the year, and where mean annual water levels (Rare) species. • Reed sweet grass (Glyceria maxima) are more than 0.25 m above the surface. • Sedges (Carex riparia, C. acutiformis, C. Annual fluctuations of between about 0 m and 0.6 m above ground Scattered sites across southern England paniculata, C. elata) level provide optimum conditions with summer water level critical from Norfolk to Dorset, with isolated • Saw sedge (Cladium mariscus) thresholds estimated to be at 0.5 m below surface ground level. populations elsewhere. Southern chalk • Reed (Phragmites australis) streams have been shown to be as • Reedmace (Typha latifolia and T. angustifolia) Humidity important as the East Anglian fens as • Branched bur reed (Sparganium erectum) Humidity is important since the snail spends much of the year strongholds for this species. • Iris (Iris pseudacorus) climbing in the canopy of the vegetation well away from the ground. • Reed canary grass (Phalaris arundinacea) Humidity regimes are likely to be influenced by vegetation structure, Adjacent to rivers, its presence/absence and which is clearly affected by management. population density are largely determined by the structure and topography of the banks and the nature of the riparian management. The most suitable riparian habitats comprise a relatively broad strip where Glyceria or Sparganium spp. form dense floating rafts on gently sloping banks. Steeper banks as a result of canalisation, impounding, channel dredging, and weed cutting reduces habitat development often resulting in the absence of the snail. 3260 Water courses of Sub-type 1 rivers on chalk substrates. The Characterised by the abundance of water- Ranunculus follows a four phase cycle of biomass development: plain to montane levels community is characterised by pond water- crowfoots Ranunculus spp., subgenus • Regrowth phase in autumn triggered by the seasonal increase in with the Ranunculion crowfoot Ranunculus peltatus in spring-fed Batrachium (Ranunculus fluitans, R. penicillatus flow. fluitantis and headwater streams (winterbournes), stream ssp. penicillatus, R. penicillatus ssp. • Extension phase over winter to April. Rapid increase in biomass Callitricho-Batrachion water-crowfoot R. penicillatus ssp. pseudofluitans, and R. peltatus and its hybrids). with the development of long streamers in spring. vegetation pseudofluitans in the middle reaches, and They may modify water flow, promote fine • Consolidation and flowering phase over late spring to summer. river water-crowfoot R. fluitans in the sediment deposition, and provide shelter and • Biomass production increases then slows as energy is invested in downstream sections. Ranunculus is food for fish and invertebrate animals. flowers and seeds. typically associated in the upper and middle Ranunculus communities are associated with • Decline phase over late summer to autumn. reaches with Callitriche obtusangula and C. assemblages of other aquatic plants e.g. platycarpa. Rorippa nasturtium-aquaticum, Callitriche spp., Sium latifolium and Berula erecta, Myriophyllum Flow Sub-type 2: This variant is found on other spp. and Myosotis scorpioides. The cover of Velocity and discharge are prime factors due to the high substrates, ranging from lime-rich these species may exceed that of Ranunculus photosynthetic rate of Ranunculus: fast flows are required to deliver substrates such as oolite, through soft species. Three main sub-types are defined by oxygen and carbon to the plant. Velocity also acts indirectly to sandstone and clay to more mesotrophic substrate and the dominant species within the remove potentially competitive or shading algae, and clearing silt and oligotrophic rocks. Ranunculus community. from gravels. 0.3 – 0.5 ms-1 optimal summer velocity band. It is recognised that Sub-type 3: This variant is a mesotrophic to Ranunculus growth can occur above the threshold of 0.5 ms-1 but oligotrophic community found on hard rocks is subject to mechanical stresses. in the north and west. Substrate Clean gravel river beds encourage Ranunculus root development and prevent the development of other algal growth which is given an advantage on soft, silty substrates.

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Species / community Designations and status General ecology Habitat requirements Habitat requirements (continued)

White-clawed crayfish Listed under annexes II and V of the EU Crayfish distribution is influenced by geology, Water quality (Austropotamobius Habitats Directive and Appendix II of the requiring relatively hard, mineral-rich waters of The majority of records for the white-clawed crayfish occur in UK pallipes) Bern Convention. Protected under calcareous catchments. The species occurs in a Environment Agency General Quality Assessment Class A and B Schedule 5 of the variety of habitats including canals, streams, waters, an indication of their association with unpolluted fluvial Wildlife and Countryside Act (1981). Priority rivers, lakes, reservoirs and water-filled quarries. systems. The white-clawed crayfish is principally found in alkaline species under the UK Biodiversity Action waters for which calcium and pH requirements are: Plan with its own Species Action Plan. It is typically found in watercourses of 0.75 m to • calcium (5 mg l-1 minimum) 1.25 m deep, but is also found in small streams • pH (6.5–9.0) Austropotamobius pallipes is widespread in (about 5 cm of water) and in deeper, slow- most parts of England and is common in flowing rivers (2.5 m). In flowing water the BOD parts of eastern Wales. It is present in white-clawed crayfish may be found associated The white-clawed crayfish is particularly susceptible to acute south-west Northern Ireland. A significant with: pollution incidents caused by spills of organic material with a high part of the EU resource is found in the UK, biochemical oxygen demand (BOD), such as cattle slurry or silage. but the species is now seriously threatened • Undermined, overhanging banks. over most of its range in Britain. • Sections exhibiting heterogeneous flow Turbidity and siltation patterns with refuges. Gills are easily clogged by sediment and this may cause physico- • Under cobbles (juveniles) and rocks in riffles, pathological changes in the long term. White-clawed crayfish tend and under larger rocks in pools. to avoid substrates covered in mud or silt unless they are actively • Among roots of woody vegetation, foraging for food. accumulations of fallen leaves and boulder weirs. Vegetation • Under water-saturated logs. White-clawed crayfish utilise aquatic macrophyte vegetation for cover and food. They may be found amongst Cladophora spp; The white-clawed crayfish is primarily Fontinalis spp.; or vascular plants such as water crowfoot and carnivorous, feeding on aquatic watercress. Their association with such vegetation may be due to macroinvertebrates and carrion. In addition, their foraging and is particularly important in shallow water habitats allochthonous material in the form of dead as they provide protection from predation and high flows. leaves may provide an important source of food.

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C.2 Potential impacts of mill modification on European interest features of the River Wensum SSSI/SAC

Mill structures Species / community Improve operability + Remove flow control Lower mill sill levels Bypass channels Fish passes Remove all protocols mechanisms

Brook lamprey Due to the range of options Due to the range of options Due to the range of Positive Positive Positive (Lampetra planeri) available under this measure available under this measure options available under Reduction of habitat Reduction of habitat Reduction of habitat severance and increase in assessment of the potential assessment of the potential this measure assessment severance and increase in severance and increase in available habitat for existing lamprey populations. positive/negative effects on positive/negative effects on the of the potential available habitat for existing available habitat for existing Reduction in vulnerability of populations to the ecological feature cannot ecological feature cannot be positive/negative effects lamprey populations. lamprey populations. anthropogenic disturbance through increase in extent be commented on at this commented on at this point. on the ecological feature Reduction in vulnerability of Reduction in vulnerability of of available habitat. point. cannot be commented on populations to populations to anthropogenic Improved ammocoete dispersal and adult migration Review of effects to be at this point. anthropogenic disturbance disturbance through increase through removal of potential barriers. Review of effects to be determined on a site-by-site through increase in extent in extent of available habitat. Increase in available habitat for all life stages. determined on a site-by-site basis following establishment Review of effects to be of available habitat. Improved ammocoete basis following establishment of options and resultant determined on a site-by- Improved ammocoete dispersal and adult migration Negative of options and resultant changes to physical habitat site basis following dispersal and adult through removal of potential Removal of barrier previously preventing colonisation changes to physical habitat e.g. flow, sediment dynamics. establishment of options migration through removal barriers. by competitive/damaging species. e.g. flow, sediment and resultant changes to of potential barriers. Increase in available habitat dynamics. physical habitat e.g. flow, Increase in available for all life stages. Design recommendations sediment dynamics. habitat for all life stages. Provision of appropriate flow velocities to ensure Negative passage is not limited to more active swimming Negative Increased connectivity species. Increased connectivity allowing colonisation of allowing colonisation of reaches by reaches by competitive/damaging competitive/damaging species. species. Design recommendations Design recommendations Provision of appropriate flow Provision of appropriate velocities to ensure passage flow velocities to ensure is not limited to more active passage is not limited to swimming species. more active swimming species.

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Species / community Improve operability + Remove flow control Lower mill sill levels Bypass channels Fish passes Remove all protocols mechanisms

Bullhead (Cottus Due to the range of options Due to the range of options Due to the range of Positive Positive Positive gobio) available under this measure available under this measure options available under Reduction of habitat Reduction of habitat Reduction of habitat severance and increase in assessment of the potential assessment of the potential this measure assessment severance and increase in severance and increase in available habitat for existing bullhead populations. positive/negative effects on positive/negative effects on the of the potential available habitat for existing available habitat for existing Reduction in vulnerability of populations to the ecological feature cannot ecological feature cannot be positive/negative effects bullhead populations. bullhead populations. anthropogenic disturbance through increase in extent be commented on at this commented on at this point. on the ecological feature Reduction in vulnerability of Reduction in vulnerability of of available habitat. point. cannot be commented on populations to populations to anthropogenic Improved dispersal and adult migration through Review of effects to be at this point. anthropogenic disturbance disturbance through increase removal of potential barriers. Review of effects to be determined on a site-by-site through increase in extent in extent of available habitat. Increase in available habitat for all life stages. determined on a site-by-site basis following establishment Review of effects to be of available habitat. Improved dispersal and adult basis following establishment of options and resultant determined on a site-by- Improved dispersal and migration through removal of Negative of options and resultant changes to physical habitat site basis following adult migration through potential barriers. Removal of barrier previously preventing colonisation changes to physical habitat e.g. flow, sediment dynamics. establishment of options removal of potential Increase in available habitat by competitive / damaging species. e.g. flow, sediment and resultant changes to barriers. for all life stages. dynamics. physical habitat e.g. flow, Increase in available Design recommendations sediment dynamics. habitat for all life stages. Negative Provision of appropriate flow velocities to ensure Increased connectivity passage is not limited to more active swimming Negative allowing colonisation of species. Increased connectivity reaches by allowing colonisation of competitive/damaging reaches by species. competitive/damaging species. Design recommendations Provision of appropriate flow Design recommendations velocities to ensure passage Provision of appropriate is not limited to more active flow velocities to ensure swimming species. passage is not limited to more active swimming species.

Desmoulin’s whorl Due to the range of options Due to the range of options Due to the range of n/a n/a Review of effects to be determined on a site-by-site snail (Vertigo available under this measure available under this measure options available under basis following establishment of options and resultant moulinsiana) assessment of the potential assessment of the potential this measure assessment changes to physical habitat e.g. flow, sediment positive/negative effects on positive/negative effects on the of the potential dynamics. the ecological feature cannot ecological feature can be positive/negative effects be commented on at this commented on at this point. on the ecological feature point. can be commented on at Review of effects to be this point. Review of effects to be determined on a site-by-site determined on a site-by-site basis following establishment Review of effects to be basis following establishment of options and resultant determined on a site-by- of options and resultant changes to physical habitat site basis following changes to physical habitat e.g. flow, sediment dynamics. establishment of options e.g. flow, sediment and resultant changes to dynamics. physical habitat e.g. flow, sediment dynamics.

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Species / community Improve operability + Remove flow control Lower mill sill levels Bypass channels Fish passes Remove all protocols mechanisms

3260 Water courses of Reduction in impoundment Reduction in impoundment will Reduction in Reduction in impoundment n/a Reduction in impoundment will result in improved plain to montane levels will result in improved flow result in improved flow regime impoundment will result in will result in improved flow flow regime for Ranunculus communities. Review of with the Ranunculion regime for Ranunculus for Ranunculus communities. improved flow regime for regime for Ranunculus effects to be determined on a site-by-site basis fluitantis and communities. Review of Review of effects to be Ranunculus communities. communities. Review of following establishment of options and resultant Callitricho-Batrachion effects to be determined on a determined on a site-by-site Review of effects to be effects to be determined on changes to physical habitat e.g. flow, sediment vegetation site-by-site basis following basis following establishment determined on a site-by- a site-by-site basis dynamics. establishment of options and of options and resultant site basis following following establishment of resultant changes to physical changes to physical habitat establishment of options options and resultant habitat e.g. flow, sediment e.g. flow, sediment dynamics. and resultant changes to changes to physical habitat dynamics. physical habitat e.g. flow, e.g. flow, sediment sediment dynamics. dynamics.

White-clawed crayfish Due to the range of options Due to the range of options Due to the range of Positive Positive Positive (Austropotamobius available under this measure available under this measure options available under Reduction of habitat Reduction of habitat Reduction of habitat severance and increase in pallipes) assessment of the potential assessment of the potential this measure assessment severance and increase in severance and increase in available habitat for existing white-clawed crayfish positive/negative effects on positive/negative effects on the of the potential available habitat for existing available habitat for existing populations. the ecological feature cannot ecological feature cannot be positive/negative effects white-clawed crayfish white-clawed crayfish Reduction in vulnerability of populations to be commented on at this commented on at this point. on the ecological feature populations. populations. anthropogenic disturbance. point. cannot be commented on Reduction in vulnerability of Reduction in vulnerability of Improved dispersal through removal of potential Review of effects to be at this point. populations to populations to anthropogenic barriers. Review of effects to be determined on a site-by-site anthropogenic disturbance. disturbance. Increase in available habitat for all life stages. determined on a site-by-site basis following establishment Review of effects to be Improved dispersal through Improved dispersal through basis following establishment of options and resultant determined on a site-by- removal of potential removal of potential barriers. Negative of options and resultant changes to physical habitat site basis following barriers. Increase in available habitat Removal of barrier previously preventing colonisation changes to physical habitat e.g. flow, sediment dynamics. establishment of options Increase in available for all life stages. of reaches by competitive and damaging species e.g. e.g. flow, sediment and resultant changes to habitat for all life stages. signal crayfish. dynamics. physical habitat e.g. flow, Negative sediment dynamics. Negative Removal of barrier previously Removal of barrier preventing colonisation of previously preventing reaches by competitive and colonisation of reaches by damaging species e.g. signal competitive and damaging crayfish. species e.g. signal crayfish.

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C.3 Potential impacts of gravel works on European features of the River Wensum SSSI/SAC

Gravel works Species / Gravel glides Gravel glides + transverse hurdles Bed raising (large scale) community

Brook lamprey Positive Positive Positive (Lampetra planeri) Provision of suitable spawning habitat for adult brook lamprey. Provision of suitable spawning habitat for adult brook lamprey as a Significant increase in the extent of suitable spawning habitat for adult brook Improvement to local water quality through turbulent flow and result of gravel installation. lamprey. resultant increase in DO concentration. Hurdle construction will promote deposition of fine sediment Improvement to local water quality through turbulent flow and resultant DO favouring ammocoete life stages. concentration. Negative Improvement to local water quality through turbulent flow and Small scale loss of silt bed areas suitable for ammocoete resultant DO concentration. Negative development. Potential for large scale loss of silt bed areas suitable for ammocoete Potential to cause damage to existing populations during gravel Negative development. placement. Small scale loss of silt bed areas suitable for ammocoete Potential to cause damage to existing populations during installation of bed development at site of gravel placement. raising measures. Design recommendations Potential to cause damage to existing populations during gravel Provision of suitably sized spawning substrate. placement. Design recommendations Glide depth and morphology to provide appropriate flow velocities Provision of suitably sized spawning substrate. that reduce fine sediment deposition. Design recommendations Glide depth and morphology to provide appropriate flow velocities that reduce Maximise flow heterogeneity through the creation of diverse bed Provision of suitably sized spawning substrate. fine sediment deposition. topography. Glide depth and morphology to provide appropriate flow velocities Maximise flow heterogeneity through the creation of diverse bed topography. that reduce fine sediment deposition. Maximise flow heterogeneity through the creation of diverse bed topography. Bullhead (Cottus Positive Positive Positive gobio) Provision of vital habitat for bullhead spawning and adult and Provision of vital habitat for bullhead spawning and adult and YOY Provision of vital habitat for bullhead spawning and adult and YOY (young of YOY (young of year) fish life stages. (young of year) fish life stages. year) fish life stages. Improvement to local water quality through turbulent flow and Diversification of in-stream flow character. Diversification of in-stream flow character. resultant increase in DO concentration. Improvement to local water quality through turbulent flow and Provision of suitable habitat for macroinvertebrate prey items and macrophyte Diversification of in-stream flow character. resultant DO concentration. cover e.g. Ranunculus. Provision of suitable habitat for macroinvertebrate prey items and Provision of suitable habitat for macroinvertebrate prey items and Improved depth through bed raising. macrophyte cover e.g. Ranunculus. macrophyte cover e.g. Ranunculus. Improved depth through bed raising. Negative Negative Potential to cause damage to existing populations during installation of bed Potential to cause damage to existing populations during gravel Negative raising measures. placement. Potential to cause damage to existing populations during gravel placement. Design recommendations Design recommendations Habitat value can be further increased through addition of larger Habitat value can be further increased through addition of larger Design recommendations stone/boulder substrates within gravel glide. stone/boulder substrates within gravel glide. Habitat value can be further increased through addition of larger Maximise flow heterogeneity through the creation of diverse bed topography. Maximise flow heterogeneity through the creation of diverse bed stone/boulder substrates within gravel glide. topography. Maximise flow heterogeneity through the creation of diverse bed topography.

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Species / Gravel glides Gravel glides + transverse hurdles Bed raising (large scale) community

Desmoulin’s whorl n/a n/a Positive snail (Vertigo Potential to improve local water level regime through more frequent moulinsiana) inundation of marginal habitats.

Design recommendations Incorporate measures such as lowering embankments and berm creation.

3260 Water Positive Positive Positive courses of plain to Provision of suitable rooting habitat for Ranunculus community Provision of suitable rooting habitat for Ranunculus community Provision of suitable rooting habitat for Ranunculus community vegetation. montane levels vegetation. vegetation. Provision of favourable flow and depth conditions for development of with the Provision of favourable flow and depth conditions for Provision of favourable flow and depth conditions for development Ranunculus vegetation. Ranunculion development of Ranunculus vegetation. of Ranunculus vegetation. fluitantis and Negative Callitricho- Negative Negative Batrachion Design recommendations vegetation Design recommendations Design recommendations Provide varied glide depth and morphology to maximise flow diversity. Provide varied glide depth and morphology to maximise flow Provide varied glide depth and morphology to maximise flow Consideration given to translocation of existing plants to encourage diversity. diversity. establishment. Consideration given to translocation of existing plants to Consideration given to translocation of existing plants to encourage encourage establishment. establishment.

White-clawed Positive Positive Positive crayfish Provision of suitable habitat and foraging area for white-clawed Provision of suitable habitat and foraging area for white-clawed Provision of suitable habitat and foraging area for white-clawed crayfish. (Austropotamobius crayfish. crayfish. Improvement to local water quality through turbulent flow and resultant pallipes) Improvement to local water quality through turbulent flow and Improvement to local water quality through turbulent flow and increase in DO concentration. resultant increase in DO concentration. resultant increase in DO concentration. Negative Negative Negative Potential to cause damage to existing populations during gravel placement. Potential to cause damage to existing populations during gravel Potential to cause damage to existing populations during gravel placement. placement. Design recommendations Glide depth and morphology to provide appropriate flow velocities that reduce Design recommendations Design recommendations fine sediment deposition. Glide depth and morphology to provide appropriate flow velocities Glide depth and morphology to provide appropriate flow velocities Maximise flow heterogeneity through the creation of diverse bed topography. that reduce fine sediment deposition. that reduce fine sediment deposition. Habitat value can be further increased through addition of larger Maximise flow heterogeneity through the creation of diverse bed Maximise flow heterogeneity through the creation of diverse bed stone/boulder substrates within gravel glide. topography. topography. Habitat value can be further increased through addition of larger Habitat value can be further increased through addition of larger stone/boulder substrates within gravel glide. stone/boulder substrates within gravel glide.

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C.4 Potential impacts of other river restoration measures on the European features of the River Wensum SSSI/SAC

Other

Species / Fencing Tree planting on Tree felling Deflector (using LWD Lower spoil Channel re- Berm creation where Backwaters – Backwaters – new Channel realignment Changing Lower community embankment and filled in with brush embankments sectioning appropriate reconnections to primary and embankments mattress) IDB, field drains secondary channels n/a Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Localised shading General Improvement of flow General improvement General improvement Berm creation will Increase in the Increase in the extent Promotion of more Potential to General improvement may inhibit improvement to in- conditions adjacent to to channel form and to channel form and increase flow velocities extent of habitat of available marginal natural flow character improve the extent to channel form and development of stream habitat deflector which will act process through process through (most effective during available for ammocoete habitat. and sediment regime of suitable process through algae, improving through to improve spawning increase in duration of increase in duration of low flow periods) and utilisation by Provision of refuge favouring habitat spawning and/or increase in duration spawning habitat encouragement of gravels through silt channel forming flows. channel forming flows. reduce local fine spawning adult or areas during high flow development for both larval habitat. of channel forming ) quality. natural narrowing removal. Increased connectivity sediment deposition larval ammocoete events. adult and larval life flows. process. Associated fine with floodplain Negative improving spawning life stages. stages. Negative Increased Design sediment deposition will features that provide Potential to cause habitat if gravels are Design Potential to reduce connectivity with recommendations Negative provide ammocoete shelter and refuge for damage to existing present. recommendations Negative habitat quality for floodplain features Incorporate Reduced shade habitat. lamprey. populations during Ensure sweetening Potential to cause ammocoete life that provide shelter additional measures may encourage implementation of Negative flow is maintained to damage to existing stages where and refuge for such as fencing to development of Negative Design measure. Potential to cause reduce risk of silting populations during primary channel lamprey. Lampetra planeri remove algae reducing Potential to cause recommendations damage to existing up of backwater implementation of provides extensive grazing/trampling spawning habitat damage to existing Incorporate with populations during features. measure. silt beds for larval pressure. quality at a local populations during additional measures implementation of development. Design scale. placement of deflector. such as gravel measure. Potential to affect recommendations placement. existing population Incorporate with Design Design Design through changes additional measures

Brook lamprey ( recommendations recommendations recommendations in water such as gravel Adopt selective Incorporate with Incorporate additional availability. placement. felling to ensure additional measures measures such as some tree cover such as gravel gravel placement and remains of varied placement. deflectors. age structure.

Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Encourage Riparian tree General Improvement of flow Increased connectivity Return of natural Localised channel Improved Provision of new Promotion of more Potential to General improvement riparian tree development will improvement to in- conditions through with floodplain channel form and narrowing may promote connectivity to habitats for natural flow character improve the extent to channel form and establishment to provide shade and stream habitat deflector installation features that provide function will promote increased flow additional habitats colonisation by and sediment regime of available process through supply shade and shelter as well as through combined with marginal shelter and refuge for conditions that will velocities, improving suitable for bullhead. favouring habitat habitat. increase in duration shelter as well as valuable input of encouragement of facilitation of fine bullhead. favour species and physical habitat colonisation by Provision of refuge development for both of channel forming valuable input of woody debris and natural narrowing sediment deposition. General improvement potentially improve conditions for bullhead. bullhead. areas during high flow adult and juvenile life Negative flows. woody debris and leaf litter. process. to channel form and densities and standing Increase in the events. stages. Potential to affect Increased leaf litter. Reduction in Negative process through crop. Negative extent of habitat existing population connectivity with Improved bank localised sediment Negative Potential to cause increase in duration of Potential to cause available for Negative through changes floodplain features stability and input through Localised removal damage to existing channel forming flows. Negative damage to existing utilisation by Design Potential to cause in water that provide shelter reduced sediment improved bank of shade and populations during Potential to cause populations during bullhead for shelter recommendations damage to existing availability. and refuge for input. stability. shelter plus gravel placement. damage to existing implementation of from high flow Ensure sweetening populations during bullhead. reduction in populations during measure. events and/or flow is maintained to implementation of ) valuable supply of implementation of additional reduce risk of silting measure. Design Design woody debris and measure. Design spawning habitat up of backwater Design recommendations recommendations leaf litter. recommendations and nursery features. recommendations Incorporate Incorporate Reduced shade Design Incorporate additional grounds. Incorporate with planting of native additional measures may encourage recommendations design measures such additional measures

Cottus gobio deciduous such as fencing to development of Incorporate additional as gravel placement such as gravel species that will remove algae reducing measures such as and deflectors. placement. provide seasonal grazing/trampling spawning habitat gravel placement. input of leaf litter. pressure. quality at a local

Bullhead ( Planting of native scale. deciduous species that will provide Design seasonal input of leaf recommendations litter. Adopt selective felling to ensure some tree cover remains of varied age structure.

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Species / Fencing Tree planting on Tree felling Deflector (using LWD Lower spoil Channel re- Berm creation where Backwaters – Backwaters – new Channel realignment Changing Lower community embankment and filled in with brush embankments sectioning appropriate reconnections to primary and embankments mattress) IDB, field drains secondary channels Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Exclusion of Reduced shading Potential for Improve connectivity Re-sectioning may Berm creation may Increase in the Backwater areas may Potential to improve Improvement of Lowering of grazing pressure Negative of wetland plant establishment of between river and favour growth of favour growth of extent of habitat improve the extent of marginal habitat water level embankments may from marginal Increased shading of communities and marginal wetland marginal habitats. If marginal plants and marginal plants and available for area available for quality. regimes in improve the extent of areas and wetland plant reduction in local vegetation on lateral silt suitable water level provided suitable provided suitable water colonisation by colonisation by adjacent floodplain area available for encouragement of communities water demand. berms. regimes are water level regimes level regimes are wetland plants. marginal plants and, Negative area through colonisation by ) marginal plant associated with snail maintained snail are maintained snail maintained snail Potential to provided suitable Potential to cause increase in ground marginal plants and, development. populations. populations may populations may populations may improve water water levels are damage to existing water levels. provided suitable Reduction in Local effects on Design benefit. benefit. benefit. levels adjacent to maintained, snail populations during water levels are poaching of water availability recommendations Improve dispersal of main river. populations may implementation of Negative maintained, snail marginal habitats. through tree uptake. Encourage species through Negative Negative benefit. measure. Potential to affect populations may vegetation improved connectivity Potential to cause Potential to cause existing population benefit. Negative Design establishment on in river corridor. damage to existing damage to existing Negative Design through changes May eventually recommendations silt berms through populations during populations during Potential to cause recommendations in water Negative Vertigo moulinsiana result in Ensure planting does transplantation of Negative implementation of implementation of damage to existing Promote suitable availability. development of not create a appropriate Potential to cause measure. measure. populations during water level regimes in Design marginal tree significant shading wetland plants. damage to existing implementation of marginal areas recommendations cover and hence impact on existing populations during Design Design measure. through appropriate Incorporate with loss of suitable suitable snail habitat. implementation of recommendations recommendations channel design. additional measures habitat. measure. Encourage marginal Encourage marginal Design such as gravel vegetation vegetation recommendations placement. Design establishment through establishment through Encourage marginal recommendations transplantation of transplantation of vegetation Encourage marginal appropriate wetland appropriate wetland establishment through

Desmoulin’s whorl snail ( vegetation plants in treated plants in treated areas. transplantation of establishment through areas. appropriate wetland transplantation of plants in treated appropriate wetland areas. plants in treated areas.

Positive Negative Positive Positive Positive Positive Positive n/a n/a Positive Positive Positive Improved bank Gradual increase in Reduction of local Improvement of flow General improvement General improvement General improvement to Promotion of natural Potential to General improvement stability may shading will, over shading will conditions favouring to channel form and to channel form and channel form and flow and sediment provide more to channel form and reduce localised time, favour more promote Ranunculus growth process through process. process. regime conducive to appropriate flow process through sediment input. shade tolerant Ranunculus downstream of flow increase in duration of Ranunculus conditions for increase in duration species. growth. Selective deflector. channel forming flows. Negative Negative communities. Ranunculus of channel forming Negative tree felling Potential to cause Potential to cause development. This flows. Development of Design encouraged rather Negative Negative damage to existing damage to existing Negative potential is

Callitricho-Batrachion riparian recommendations than widespread Potential to cause vegetation stands vegetation stands Potential to cause improved if Negative vegetation will Provide varied shade removal to provide damage to existing Design during implementation during implementation damage to existing secondary channel

and increase shading, pattern through a mosaic of shade vegetation stands during recommendations of measure. of measure. communities during contains more Design increasing selective planting and light habitats. implementation of Incorporate with implementation of appropriate recommendations competition from locations. measure. additional measures Design Design measure. substrate e.g. Incorporate with more shade Negative such as gravel recommendations recommendations areas of gravel. additional measures tolerant species. Potential to Design placement. Incorporate with Incorporate with such as gravel increase the recommendations additional measures additional measures Negative placement. development of Incorporate with such as gravel such as gravel Potential to affect competitive algal additional measures placement. placement. existing stands of

Ranunculion fluitantis species e.g. such as gravel vegetation through epiphytes. placement. changes in water availability.

Design recommendations Incorporate with additional measures such as gravel placement.

vegetation vegetation 3260 Water courses of plain to montane levels with plain levels with courses of the montane to 3260 Water Unit 51 North Elmham Mill to Elsing Mill_Final for issue.docx 170

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Species / Fencing Tree planting on Tree felling Deflector (using LWD Lower spoil Channel re- Berm creation where Backwaters – Backwaters – new Channel realignment Changing Lower community embankment and filled in with brush embankments sectioning appropriate reconnections to primary and embankments mattress) IDB, field drains secondary channels Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Encourages Riparian tree Reduction of local Improvement of flow General improvement Return of natural Localised channel Increase in Increase in available Promotion of more Potential to General improvement riparian tree development will shading will conditions adjacent to to channel form and channel form and narrowing may promote available habitat habitat and dispersal natural flow character improve the extent to channel form and establishment to provide shade and promote increased deflector which will act process through function will promote increased flow velocities and dispersal for for existing white- and sediment regime of available process through supply shade and shelter as well as in-stream to improve habitat increase in duration of conditions that will improving physical existing white- clawed crayfish favouring habitat habitat. increase in duration ) shelter as well as valuable input of productivity, quality for white-clawed channel forming flows. favour this species. habitat conditions for clawed crayfish populations. development for of channel forming valuable input of woody debris and potentially crayfish. white-clawed crayfish. populations. Reduced vulnerability white-clawed crayfish. Negative flows. woody debris and leaf litter. increasing Negative Reduced to anthropogenic Potential to affect leaf litter. Reduction in availability of food Negative Design Potential to cause Negative vulnerability to disturbance. Negative existing population A. pallipes Improved bank localised sediment items. Potential to cause recommendations damage to existing Potential to cause anthropogenic Potential to cause through changes Design stability and input through damage to existing Incorporate with populations during damage to existing disturbance. damage to existing in water recommendations reduced sediment improved bank populations during additional measures implementation of populations during populations during availability. Incorporate with input. stability. gravel placement. such as gravel measure. implementation of Negative implementation of additional measures placement. measure. Removal of barrier measure. such as gravel Design Design previously placement. Design Design recommendations recommendations Design preventing recommendations recommendations Incorporate with Incorporate additional recommendations colonisation of Incorporate Planting of native additional measures measures such as Incorporate additional reaches by planting of native deciduous species such as gravel gravel placement. design measures such competitive and White-clawed crayfish ( deciduous that will provide placement. as gravel placement damaging species species that will seasonal input of leaf and deflectors. e.g. signal crayfish. provide seasonal litter. input of leaf litter.

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Appendix D – Links between terrestrial and riverine units of the River Wensum SSSI

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Appendix D – Links between terrestrial and riverine units of the River Wensum SSSI units

Terrestrial Riverine RWRS reach / Details of Terrestrial SSSI unit Natural England comments on Action SSSI SSSI reaches linkage between terrestrial and units units riverine SSSI units Name: Swanton Morley Parish Council Land  Hydrological relationship between Conceptual design proposes: 33 (Full 51 15 river and floodplain significantly SSSI ID Location: TG 020 187 impacted through impoundment  Reinstatement of natural 1023138) immediately downstream at Area: 3.97ha hydrological regime to Unit 33 Waterfall Farm. SSSI through lowering of Therefore,hydrological connectivity Type: Neutral grassland – lowland adjacent embankments and not appropriate. reconnections to the existing  Feasibility study for river restoration Condition Assessment : Unfavourable drainage network. needs to consider the opportunities  In-stream works include berm recovering (assessed January 2010) for reconnection of the appropriate creation, resectioning and gravel hydrological relationship between glide installation. Management: Vegetation semi-natural and the river and this unit of the SSSI. dominated by floodplain habitats. Low intensity  Tree planting. summer grazing regime compatible with special interest of the river. Surveys indicate that the reed-bed areas are too dry to support Desmoulin's whorl-snail. Name: Mill Street East Swanton Morley Farms  There are low spoil banks between Conceptual design proposes: 34 (Full 51 14 the river and Unit 34. SSSI ID Location: TG 020 178  The whole river is regarded as 1023139)  Improvement to hydrological being influenced by the regime to SSSI Units 34 and 36 Area: 0.96ha impoundment at Mill Street (Elsing through reconnections to the Mill). However, there is a gravel existing drainage network. Type: Neutral grassland – lowland glide at Castle Farm which is likely  In-stream and marginal works

to have been used to ford the river include berm creation, deflector Condition Assessment: Unfavourable and which acts as an impoundment installation and embankment recovering (assessed February 2010) to upstream reaches. lowering.

 A feasibility study for the  Selective tree planting and tree Management: Vegetation semi-natural and restoration of river Unit 51 is thinning. dominated by floodplain and valley side required in order to assess whether  Channel realignment to bypass habitats. A low intensity summer grazing improvement can be made in the regime has been reintroduced to this site, and Elsing Mill and changing primary hydrological regime between river flow routes at existing flow this is compatible with special interest of the and floodplain. river. bifurcation points.

Name: Mill Street Swanton Morley Parish  Given the sloping nature of much of Conceptual design proposes: 35 (Full 51 14 Council this ground, the hydrological SSSI ID relationship between river and  Improvement to hydrological Location: TG 020 177 floodplain is regarded as being

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Terrestrial Riverine RWRS reach / Details of Terrestrial SSSI unit Natural England comments on Action SSSI SSSI reaches linkage between terrestrial and units units riverine SSSI units 1023164) appropriate. regime to SSSI Units 34 and 36 Area: 0.25ha through reconnections to the existing drainage network. Condition Assessment : Unfavourable  In-stream and marginal works recovering (assessed January 2010) include berm creation, deflector installation and embankment Type: Broadleaved, mixed and yew woodland lowering. - lowland  Selective tree planting and tree thinning. Management: This unit occupies flushed  Channel realignment to bypass valley side, with a fringe of swamp vegetation Elsing Mill and changing primary at the river’s edge. Vegetation semi-natural flow routes at existing flow and dominated by floodplain and valley side bifurcation points. habitats. Non intervention regime, compatible with the special interest of the river. Name: Mill Street South East Swanton Morley  There are low spoil banks along Conceptual design proposes: 36 (Full 51 14 Farms part of the riparian margin of Unit SSSI ID 34. 1023140)  Improvement to hydrological Location:  At this point, the river is regarded regime to SSSI Units 34 and 36 as being influenced by the through reconnections to the Area:2.39ha impoundment at Mill Street. existing drainage network.

However, there is a gravel glide at  In-stream and marginal works Type: Neutral grassland – lowland Castle Farm which is likely to have include berm creation, deflector

been used to ford the river and this installation and embankment Management: Vegetation semi-natural and acts as an impoundment to lowering. dominated by floodplain and valley side upstream reaches.  Selective tree planting and tree habitats. Low intensity summer grazing  A feasibility study for the thinning. regime on south-eastern field and no grazing restoration of river Unit 51 is  Channel realignment to bypass regime on the north-eastern ground required in order to assess whether compatible with special interest of the river. Elsing Mill and changing primary improvement can be made in the flow routes at existing flow hydrological regime between river bifurcation points. and floodplain.

Notes – 1. ‘Terrestrial SSSI units’ refers to non-riverine units of the River Wensum SSSI (e.g. SSSI ID 1023138). 2. ‘Riverine SSSI units’ refers to those units of the River Wensum SSSI that comprise sections of river channel (e.g. Unit 51). 3. ‘RWRS reaches’ refers to reaches of river channel as defined in the River Wensum Restoration Strategy (e.g. Reach 14, Elsing Reach). 4. ‘Details of terrestrial SSSI unit’ are taken from Nature on the Map: http://www.natureonthemap.org.uk/ 5. ‘Natural England comments on linkage between terrestrial and riverine SSSI units’ are those from an emerging condition assessment of terrestrial SSSI units undertaken by Natural England. The condition assessment is thus far incomplete and in draft form.

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6. ‘Action’ refers to those proposed options/measures in the conceptual design undertaken by Atkins. 7. Changes in river / floodplain hydrology will be considered at detailed design stage as modelling will be required to determine the extent of the relationship. It is inappropriate at this stage due to the potential complexity of this relationship. Reasons stated for “unfavourable condition” of individual SSSI units will be included in the drivers for the design.

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