Lower River Test NEP Volume 1

Home , Cadnam, Lower Test Valley, River Test

Volume 1: Report

Southern Water Services

October 2012

CD Copy 3/10: Louise Bardsley, Natural England Lower Test NEP This report is provided on the basis it will not be circulated. Receipt of the report implies agreement not to circulate it. The circulation or publication of information within this report without the express permission of Southern Water Services Ltd will be in breach of the Security and Emergency Measures Direction. Notice

This document and its contents have been prepared and are intended solely for Southern Water Services‟ information and use in relation to the Lower River Test NEP Atkins Limited assumes no responsibility to any other party in respect of or arising out of or in connection with this document and/or its contents.

Document history

Job number: 5099146 Document ref: 5099146 / 076 / DG / 156 Revision Purpose description Originated Checked Reviewed Authorised Date Rev 1.0 For Steering Group review Atkins HG BP, AB, MP BP 27 02 12 Rev 1.1 For Steering Group review Atkins HG BP BP 13 04 12 Rev 1.2 For Steering Group review Atkins HG PS PS 27 07 12 Rev 1.3 Issued to Stakeholders Atkins HG PS PS 24 10 12

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Client Southern Water Services Project Lower River Test NEP Document title Lower River Test NEP Job no. 5099146 Copy no. Document

reference

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1. Introduction ...... 1 1.1. Background context ...... 1 1.2. Work by the Environment Agency ...... 2 1.3. Introduction to the Lower Test NEP Investigation ...... 3 1.4. Scope of the NEP Investigation ...... 5 1.5. Abstraction ...... 9 1.6. The Water Framework Directive and Catchment Abstraction Management Strategy ...... 11 2. Ecological Baseline ...... 19 2.1. Nature conservation designations...... 19 2.2. Fisheries ...... 28 2.3. Aquatic Macrophytes ...... 32 2.4. Benthic Macroinvertebrates ...... 35 2.5. Protected Species ...... 36 2.6. Floodplain macroinvertebrates ...... 38 2.7. Wetland Habitat/Flora ...... 39 2.8. Breeding waders and passerines...... 42 2.9. Intertidal habitats ...... 43 3. Physical environment and water management ...... 44 3.1. Climate ...... 44 3.2. Soils and geology ...... 44 3.3. Topography ...... 45 3.4. Flow splits ...... 46 3.5. Hydrology of the Lower River Test...... 46 3.6. Tidal influence ...... 49 3.7. Structures and water level management ...... 49 3.8. Geomorphology...... 53 4. Modelling the Lower River Test ...... 64 4.1. Infoworks Hydraulic Model ...... 64 4.2. The Wetland Model ...... 65 4.3. The Thermal Model ...... 66 4.4. The Salmon Movement Model ...... 67 5. Hydrological regime ...... 68 5.1. Water level monitoring ...... 68 5.2. Modelling the hydrological regime ...... 71 5.3. Conclusions ...... 87 6. Fisheries Appraisal ...... 90

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Tables

Table 1.2.1 Scope of the fisheries and ecological assessment for the Lower Test NEP ...... 6 Table 1.5.1 Summary statistics for the Testwood PWS abstraction ...... 11 Table 1.5.2 Annual statistics for the Testwood PWS abstraction ...... 11 Table 1.6.1 Summary of Abstraction Sensitivity Band typologies ...... 15 Table 1.6.2 EFI Compliance and non-compliance percentages of Qn95 ...... 15 Table 1.6.3 Water body summary table ...... 16 Table 1.6.4 Southampton Water: Mitigation measures that have defined Good Ecological Potential ...... 17 Table 1.6.5 The Natural England Conservation Objective Flow Target for the River Test SSSI ...... 18 Table 2.1.1 The ecological designations in or adjacent to the Lower Test ...... 19 Table 2.1.2 Summary Condition Assessment for Unit 91 of the River Test SSSI ...... 20

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Figures

Figures are contained in Volume 2, which is separate to this document.

Appendices

Appendices are contained in Volume 3, which is separate to this document.

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1.1. Background context

This report covers the investigation of the potential effect of the Testwood abstraction upon the Lower River Test and associated riverine ecology. Figures 1.1.1 to 1.1.3 show the location of the River Test, and Figure 1.1.4 presents a schematic of the Lower Test river system. The Environment Agency has called for the effect of the abstraction at Testwood upon the Lower River Test to be examined as part of its National Environment Programme (NEP) list of schemes. The Environment Agency (2010a, p6) has stated that: “The principle need for an investigation into the effect of abstraction on the lower River Test originated from the Test & Itchen Catchment Abstraction Management Strategy (CAMS) in March 2006. The CAMS resource assessment classified the Testwood Gauging Station and Test Total assessment points as being „Over-licensed‟ at low flows. This indicated that there appeared to be no adverse effect on the ecology of the river under current abstraction rates. However, it also indicated that if current abstraction licence holders were to take their full licensed quantities, then there might be an adverse effect on the ecology of the lower River Test. “CAMS provides a relatively high level resource assessment which seeks to identify where risks to the water environment may be elevated due to abstraction. In order to fully understand whether such risks are significant, a more detailed level of investigation is required. One of the outcomes of the CAMS assessment was therefore a requirement to [first] investigate the effect of current and fully licensed abstraction on the ecology of the Lower Test. It also identified a [second] action to investigate potential flow distribution solutions should adverse ecological effects be found1. One of the challenges of such an investigation will be that the CAMS indicates that there are unlikely to be any adverse effects arising from the current abstraction regime, meaning that the assessment will be addressing potential ecological effects rather than measured and/or observed effects. “In addition to the CAMS, the River Test SSSI‟s lower Test Unit 91 is categorised by Natural England as being in „Unfavourable – no change‟ condition with two of the seven potential factors underlying this being cited as abstraction and inappropriate water levels. The abstraction factor is based on the CAMS classification and may be updated if “better science” becomes available through the investigation showing there is no significant adverse effect on the ecology of the river. Further input from Natural England will be necessary to determine whether the water level factor, in respect of the main river SSSI, is relevant to this investigation. “Further to this the Water Framework Directive assessment has classed the hydrology element of the Lower Test water body as „not supporting good ecological status‟. The first River Basin Management Plan (RBMP) is an initial assessment and based on the ecological data available at the time. This is therefore an indication of the status of the ecology and will be developed over the next few years before being included in the second RBMP. As a result of the concerns raised by these various categorisations, the lower Test was placed in the Environment Agency‟s (EA) Restoring Sustainable Abstraction Programme (RSA) which catalogues those sites where the environment may be at risk from abstraction, and examines and resolves those concerns. “The RSA project to investigate these concerns was included in the PR09 National Environment Programme which requires water companies to undertake improvement schemes which are agreed and subsequently incorporated into their business plans.”

1 Please note that an NEP investigation is structured into two stages: the first is an examination of the effects of different abstraction scenarios, and if any deleterious effects are found then the second stage comprises an appraisal of different mitigation options or solutions.

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The Lower Test NEP project sits within a wider framework of projects, as displayed in Figure 1.1.5, particularly with regard to the preceding AMP2 period (AMP4) the current AMP (AMP5) and the next AMP (AMP6). The Lower Test NEP investigations are looking at the effect of the Testwood PWS abstraction on the River Test, and the results will also feed into Testwood-Otterbourne Project, and ultimately the 2014 Water Resources Management Plan. In AMP4, the River Itchen Sustainability Reduction investigation concluded that a sustainability reduction was required. In order to abstract water from the Lower Test to satisfy the deficit caused by the River Itchen Sustainability Reduction, it is necessary to increase the current capacity of the treatment work at the Testwood works, and construct a pipeline (the Testwood-Otterbourne Project).The Hampshire and Isle of Wight Options Appraisal is considering how to achieve the River Itchen Sustainability Reduction from the available options, including water from the River Test, water from groundwater augmentation schemes, and other options.

1.2. Work by the Environment Agency

1.2.1. The Lower Test project

In response to the results for the lower River Test from the Test & Itchen Catchment Abstraction Management Strategy (CAMS) in 2006, and as a follow-on to the River Test WLMP (Environment Agency, 2006), the “Environment Agency Lower Test Project” commenced in December 2008 to address a number of issues relating to the lower River Test in an integrated way. In this project, the Environment Agency undertook a comprehensive review of all relevant baseline data and known and available information relating to the Lower Test. Two key documents were produced, as follows:  Baseline Data Report (Environment Agency (2011c) – this report collated a significant amount of relevant existing data and information relating to the Lower River Test; and  Flow Diversion Scoping Report (Environment Agency (2009a) – this report collates data and information relating to three possible flow diversion schemes in the area which have been discussed for some time by the Environment Agency. The three schemes are the Broadlands Fish Farm Carrier, Great/Little Test Split and Nursling Fish Farm Carrier. The collated data and information contained within these reports have been used to underpin the NEP investigation.

1.2.2. The Abstraction Impact report

Following the work outlined in Section 1.2.1, the Environment Agency produced a document (Environment Agency, 2010a) that looked to develop a scope of work to assess the effect of the Testwood Public Water Supply (PWS) abstraction on the ecology of the lower River Test. The report, „Testwood Public Water Supply Abstraction Impact Investigation – Statement of Issues and Assessment‟, examined the habitats and species of the Lower Test and assessed whether they may be vulnerable to a change in the hydrological regime due to abstraction, together with the issues, assessments and monitoring that would need to be considered. The Steering Group has used this document in its identification of the scope of this NEP investigation, see Section 1.4.

2 AMP stands for Asset Management Plan which is the Water Industry‟s 5 yearly planning and investment cycle.

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The focus of the Lower Test National Environment Programme (NEP) investigation is to assess the potential effects of different abstraction scenarios at Testwood on the hydrological regime and associated riverine ecology downstream of the Testwood intake and the associated habitats and species of the River Test SSSI and the Lower Test Valley SSSI. Figures 1.1.1 to 1.1.3 show the location of the River Test, and Figure 1.1.4 presents a schematic of the Lower Test river system. An NEP investigation is structured into two stages: the first is an examination of the effects of different abstraction scenarios, and if the conclusion is that the abstraction does have a significant impact then a second stage comprises an appraisal of different mitigation options or solutions. This report comprises the first stage of the NEP investigation.

1.3.1. The Testwood abstraction

Southern Water Services (SWS) abstract water for public supply from the river, serving the Hampshire area and the Isle of Wight. Southern Water‟s abstraction licence (no. 11/42/18.16/546) for the Testwood Water Supply Works (WSW) on the River Test authorises abstraction at a peak rate of 1.58 m3/s (136.38 Ml/d) up to an annual total of 49,915,080 m3 (49,915 Ml) (equivalent to 366 days at the peak rate). More information on the Testwood Abstraction is presented in Section 1.5.

1.3.2. The River Test SSSI

The River Test is a classic chalk stream, and is longer and larger than its neighbour, the River Itchen. It is located in the county of Hampshire and is approximately 50 km in length, with a catchment area of 443 ha. The River Test rises in Overton near Basingstoke and flows to Nursling near Southampton, and enters Southampton Water. Downstream of Romsey, the River Test meanders through a wide floodplain flanked by old water meadows before passing through the inter-tidal habitats of the Lower Test Nature Reserve into Southampton Water at Redbridge. The river is heavily braided with a complex flow distribution. The River Test was notified as a SSSI in 1996, with significant areas of semi-natural vegetation in the floodplain included in the designation. Thus, in addition to the river system itself, the SSSI supports some extensive areas of floodplain grassland, fen, reed bed, wet woodland, scrub and areas of open water. The SSSI designation extends throughout its length to the normal tidal limit; the floodplain below this limit has European level protection through the designations of the Solent Maritime Special Area of Conservation (SAC), Solent and Southampton Water Special Protection Area (SPA) and the Solent and Southampton Water Ramsar site. More information on the River Test SSSI is presented in Section 2.

1.3.3. The study area and time period

This NEP investigation focuses on the lower reach of the River Test SSSI: the reach of the river downstream of the M27, and upstream of the river‟s entry into Southampton Water, see Figure 1.1.2. The time period considered by the investigation is 1996–2011. The reason for this particular time period is that this is when reliable and robust flow measurements are available from Testwood Gauging Station; see Section 3.5 for more information of the hydrological characteristics of this time period.

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1.3.4.1. Steering Group In order to engage with the key regulatory stakeholders over the proposed scope and approach to the NEP investigation, and to allow for discussions of emerging outcomes, a Steering Group was created that met regularly during the course of the project. The Steering Group comprised members of SWS, Atkins, Adams Hendry, Natural England and the Environment Agency. The Steering Group met at the beginning of the project to discuss the approach to the project and subsequently approved the Scope of the NEP investigation (see Section 1.4). Further meetings were then held at regular intervals to discuss data and other information that had been collated, including preliminary presentation of outcomes from the investigation, and to seek guidance and endorsement on its continued direction. Drafts of this Report have been circulated to Steering Group members with meetings held to discuss findings and conclusions. SWS and Atkins are grateful to all members of the Steering Group for their time and input to the project.

1.3.4.2. Stakeholders SWS identified from the outset of the NEP investigation that there was a need for wider engagement than the Steering Group, particularly with key landowner and angling interests within the Lower Test Valley area. SWS, Atkins and Adams Hendry met separately at the outset of the project, with representatives of key landowners and the leaseholders for fishing rights on the Lower River Test, together with the Test & Itchen Association and the Hampshire & Isle of Wight Wildlife Trust. The purpose of the investigation and the relationships with other SWS investigation work being carried out in AMP5 was explained, and there was a discussion of any issues arising, including access to land and water courses for surveys and investigations. In these discussions, the landowners and fishing-rights leaseholders raised concerns about potential disturbance to anglers resulting from surveys and investigations. SWS and Atkins determined that surveys and investigations would need to be delayed from the original intended timetable to allow for more consideration to take place of this sensitive issue. Subsequent to this, limited access to parts of the Lower Test was negotiated during the fishing season with the landowners and leaseholders, with further access being allowed beyond the close of the season. Atkins has continued to liaise with the stakeholders during the NEP investigation; further specific briefings have been held with particular stakeholders to explain outcomes from modelling work being undertaken in the investigation, and the results of an analysis of migrating fish count data and other recorded information. SWS and Atkins are grateful to the Stakeholders for their time and input to the project.

1.3.5. Structure of this Report

The structure of this report is set out below. In order to make the report more readable, all figures and appendices have been collated into a separate volume for ease of reference. The references used in this report are presented in the reference list located at the end of this report.

 Section 1 Introduction The context of the NEP investigation and the Testwood abstraction.

 Section 2. Ecological A review of the biodiversity and ecological quality of the study area with Baseline reference to the wider River Test, and the surveys undertaken for the NEP study.

 Section 3. Physical A description of the physical environment of the study area in terms of environment and water hydrology, hydromorphology and water level control structures and the management monitoring undertaken for the NEP study.

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 Section 4. Modelling the An introduction to the approach taken to model and monitor the River Lower River Test Test for the NEP investigation.

 Section 5. Hydrological The hydrological regime is described in this section, with particular regime regard to flows, water levels and the effect of different abstraction scenarios.

 Section 6. Fisheries This section details the background and results of analysis using Appraisal salmon count data from the River Test.

 Section 7. Ecological For each of the key biotic factors, an ecological assessment is made to appraisal assess the existing status and the effect of abstraction and other activities. The assessment includes: aquatic macrophytes; benthic macroinvertebrates; protected species that have not been assessed elsewhere (otters, water voles, white clawed crayfish, Southern Damselfly); floodplain macroinvertebrates; wetland habitats (including lowland wet grassland habitat); breeding waders and passerines, and intertidal habitat.

 Section 8 Conclusions This section presents a summary of the key findings from each of the preceding Sections, summarises the effects of abstraction upon each ecological receptor and discusses the implications of the findings in the context of an integrated assessment of the effects of abstraction. It then provides concluding comments from the work presented and recommendations.

The figures and appendices are presented in separate volumes.

1.4. Scope of the NEP Investigation

The Scope of this NEP investigation has been agreed by members of the NEP Steering Group that comprises representative from Southern Water, the Environment Agency and Natural England, see Section 1.3.4.1. The Scope was developed taking into account the report by the Environment Agency (March 2010a), previous studies and available data, discussions with staff from the Environment Agency and Natural England, information from key landowners and their tenants. Appendix 1.2.1 presents the Scoping Document agreed by the Steering Group, and a summary of the key tasks is shown in Table 1.2.1. The effect of the abstraction upon the hydrological and ecological features of the study area were each assessed using three different abstraction scenarios:  Naturalised i.e. no abstraction at Testwood;  Historic i.e. assessing the actual abstraction that has occurred; and  Fully licensed i.e. the daily peak rate of 1.58 m3/s (136.38 Ml/d) (the annual total of 49,915,080 m3 divided by 366 days). Section 1.5 presents the annual total of historic abstraction compared with the licensed total.

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Table 1.2.1 Scope of the fisheries and ecological assessment for the Lower Test NEP

(Adapted from Table 2 in Appendix 1.2.1) The first five columns comprise information taken from the Environment Agency‟s report (March 2010) Testwood Public Water Supply Abstraction Impact Investigation– Statement of Issues and Assessment, Version 2.0. Stated assessment Stated monitoring Stated new tools / Atkins‟ interpretation of the EA Abstraction Species The Environmental outcomes that are expected are: The Scope of the Lower Test NEP Rationale requirements requirements models required Impact Report The report states that a methodology to assess the impacts of different abstraction regimes on salmon  A flow regime in the lower River Test that maintains or improves migration is needed. Examination of salmon passage for migrating salmon behaviour and the understanding of how abstraction  The effective screening of all abstraction intakes to prevent fish Effect of abstraction regimes regimes may impact on the flow regime – total The outputs of the salmon being drawn in and trapped at any stage of their life cycle on hydrological and Tool to look at impact The potential effect of different abstraction Flow, water discharge, water levels, velocity profiles etc – are assessment will guide the Salmon  temperature and impact of different flow scenarios on temperature and salmon The maintenance of a water temperature profile in the lower temperature, migration important. Should estimate the effects of potential consideration of other fish River Test which is not raised as a result of increased abstraction upon migration of salmon scenarios migration will be examined. delays in migration on salmon populations. Water species populations. and is as resilient as possible to climate change temperature profile in the lower River Test reaches  A flow regime that maintains or improves water quality in the should also be monitored and the likely impact of River Test for salmonid populations increased abstraction on this plus potential climate change scenarios and effect on salmon. Although the flow requirements for sea trout  A flow regime in the lower River Test that maintains or improves differ slightly that detailed for passage for migrating sea trout Although the flow requirements for sea trout differ salmon can used for both  The effective screening of all abstraction intakes to prevent fish slightly that detailed for salmon can used for both species. However the impact Flow, water Sea Trout being drawn in and trapped at any stage of their life cycle As salmon work species. However the impact on sea trout of any As salmon work on sea trout of any changes temperature, migration  changes in water temperature identified in the The maintenance of a water temperature profile in the lower in water temperature salmon work should be assessed separately River Test which is not raised as a result of increased abstraction identified in the salmon work and is as resilient as possible to climate change should be assessed separately  The maintenance of a flow regime in the lower River Test which does not cause brown trout habitat to be reduced or degraded • the effective screening of all abstraction intakes to prevent fish The report states that "the River Test below the being drawn in and trapped at any stage of their life cycle Testwood public water supply intake is not Not considered required by the Brown trout  The maintenance of a water temperature profile in the lower n/a n/a n/a n/a characteristic Brown Trout habitat therefore no Environment Agency River Test which is not raised as a result of increased abstraction specific monitoring is required for this species.” and is as resilient as possible to climate change  The maintenance of good water quality with high levels of dissolved oxygen  The maintenance of a flow regime in the lower River Test which does not cause grayling habitat to be reduced or degraded  The effective screening of all abstraction intakes to prevent fish being drawn in and trapped at any stage of their life cycle Not considered required unless The report states that only there is only a need to Grayling  The maintenance of a water temperature profile in the lower n/a n/a n/a n/a salmon assessment shows an assess grayling if the salmon work shows an impact River Test which is not raised as a result of increased abstraction impact and is as resilient as possible to climate change  The maintenance of good water quality with high levels of dissolved oxygen  The maintenance of a flow regime in the lower River Test which does not cause eel habitat to be reduced or degraded The report states no specific monitoring is required Not considered required by the Eel n/a n/a n/a n/a  The effective screening of all abstraction intakes to prevent eels for this species Environment Agency being drawn in and trapped at any stage of their life cycle  The maintenance of a flow regime in the lower River Test which does not cause bullhead habitat to be reduced or degraded  The effective screening of all abstraction intakes to prevent fish Water level control structures being drawn in and trapped at any stage of their life cycle can have a large impact on An assessment of the effect of different  The maintenance of a water temperature profile in the lower The report states that no specific monitoring needed water levels. Thus assess the abstraction scenarios on water levels in the Bullhead River Test which is not raised as a result of increased abstraction Impact on water levels n/a As salmon work but should assess impact of abstraction on water effect of the abstraction alone reach downstream of the abstraction to the and is as resilient as possible to climate change levels downstream of the intake upon water levels it is important next control structure will be undertaken  he maintenance of good water quality with high levels of to note the effect of control dissolved oxygen structures  The maintenance of a flow regime which prevents water levels in appropriate Bullhead habitats from being reduced to below 5 cm.  a flow regime in the lower River Test that maintains or improves passage for migrating lampreys  the effective screening of all abstraction intakes to prevent lamprey being drawn in and trapped at any stage of their life cycle Not considered required by the The report states that only need to assess if salmon  the maintenance of a flow regime in the lower River Test which Environment Agency unless Lamprey n/a n/a n/a work shows an impact, but does not specify what the n/a does not cause lamprey habitat to be reduced or degraded salmon assessment shows an assessment should be  The maintenance of water levels which do not prevent or impede impact access for Lamprey migrating up or down stream.  The maintenance of a flow regime which does not reduce water quality  The maintenance of good water quality Water vole  The maintenance and if necessary restoration of water vole Impact on water levels Population distribution Tool to assess The report requests a survey of distribution, and We will use existing data on water vole The focus of the NEP will be to

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Lower Test NEP This report is provided on the basis it will not be circulated. Receipt of the report implies agreement not to circulate it. The circulation or publication of information within this report without the express permission of Southern Water Services Ltd will be in breach of the Security and Emergency Measures Direction. Stated assessment Stated monitoring Stated new tools / Atkins‟ interpretation of the EA Abstraction Species The Environmental outcomes that are expected are: The Scope of the Lower Test NEP Rationale requirements requirements models required Impact Report populations within the lower Test to a favourable conservation and water level channel water levels changes from water levels. distributions and examine effect of different examine hydrological changes of status. impact abstraction scenarios upon water level the abstraction and impact on  Favourable conservation status will be defined when: changes in areas noted for this species hydroecological requirements. A o population dynamics data indicate that it is maintaining distribution survey will therefore itself on a long-term basis as a viable component of its not be undertaken natural habitats; o the natural range of water vole in the lower Test is neither being reduced nor is likely to be reduced for the foreseeable future; and o there is, and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis  The maintenance and restoration of wetland habitats upon which otters are dependent  The maintenance and if necessary restoration of otter populations within the lower Test to a favourable conservation status. We will use existing data on otter distributions Where the "features of  Favourable conservation status will be defined when:- and examine effect of different abstraction importance" cannot be o Impact on "identified population dynamics data indicate that it is maintaining Tool to assess scenarios upon "features of importance" where hydrologically linked to Otter features of importance to n/a itself on a long-term basis as a viable component of its channel water levels hydrologically relevant. We will engage in abstraction then these will not be otters" natural habitats; consultation with EA and NE to determine examined within the NEP (e.g. o the natural range of water vole in the lower Test is neither these "features of importance" predation) being reduced nor is likely to be reduced for the foreseeable future; and o there is, and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis. Report states that need to: collate data on the  With apparent and predicted rises in sea level, it is important that number and distribution of breeding waders in the It is not the scope of an NEP the habitat suitable for breeding waders is able to migrate Lower Test Marshes over a five year period using investigation to examine effects We will collate existing data on number and landwards. This should not be compromised by abstraction of data collected by the Hampshire and Isle of Wight of water table or water level distribution of breeding waders. We will identify water and subsequent changes to ground water levels and the Wildlife Trust, review this data in the light of predicted changes in relation to non- if historic, existing and proposed breeding seasonal flooding and drying of the flood plain necessary to sea level rise, changes in habitat/vegetation abstraction related effects such Breeding Impact on habitat water Tool to assess areas are hydrologically linked to the effects of create the specific micro-habitats necessary to support breeding n/a distribution and planned land management regimes as predicted sea level rise, Waders tables channel water levels abstractions scenarios, and if so determine the wader populations. in the Lower Test Marshes and adjacent Manor Farm changes in habitat/vegetation impact on water levels and water tables from  meadows, assess any likely adverse effects of distribution and planned land Abstraction from the lower river Test should not reduce or these scenarios, plus the role of water level compromise the ability to manage water levels in the flood plain abstraction on breeding wader habitat through management regimes in the control structures to encourage the restoration of viable populations of breeding reductions in ground water levels and flood plain Lower Test Marshes and wading birds in the face of sea level rise. inundation within the target areas for breeding wader adjacent Manor Farm meadows. habitat restoration. Report states that need to: review data on breeding We will collate existing data on number and passerines in the Lower Test Marshes using  Sufficient flow is required in the main river to maintain the range distribution of passerines. We will identify if CBC/BBS results, map locations and habitats of of reed swamp and fen vegetation types needed by this group of historic, existing and proposed breeding areas breeding passerines, assess water level nesting birds Impact on habitat water Tool to assess are hydrologically linked to the effects of Passerines n/a requirements for habitats supporting breeding  tables channel water levels abstraction scenarios, and if so determine the Sufficient flow is provided to maintain a supply of water to the passerines, assess effects of abstraction on habitat Middle River and restore/maintain transition of reed bed, swamp impact on water levels and water tables from quality and ensure measures are in place to maintain and saline influence habitats. these scenarios, plus the role of water level sufficient flow to support target water levels in terms control structures of both duration and time of year. Southern  Southern Damselfly would not be expected to inhabit the area Not considered required by the n/a n/a n/a The report states no monitoring is required n/a damselfly downstream of the public water supply abstraction. EA The maintenance of a flow regime in the lower River Test which:  maintains a habitat as characterised by the long-term health of We will undertake aquatic the invertebrate population, downstream of the abstraction The report states that 2 x samples per season macroinvertebrate surveys from intake. Macro- (spring and autumn) are needed at established the sites to determine the effect  Maintains habitats required to support the diverse and rare fauna Aquatic invertebrates Tool to deliver flow sites u/s and d/s of the intake, identified to of different abstraction present in the lower River Test Impact on flow macroinvertebrate The report states no monitoring is required – main river thresholds species level. EA believe existing/historic scenarios. We will try to  population channel To deliver the first outcome, an ecological minimum flow must be dataset not considered robust enough for use generate a robust relationship set. This will use invertebrate community data, specifically LIFE due to perceived methodological issues. between macroinvertebrates and scores and correlating them to gauged daily flows. The „tipping flow. point‟ will be when the communities no longer achieve what is expected of such a diverse, abundant ecosystem. We will consult EA and NE for The report states the following is needed: "(1) the hydroecological Survey of wetland invertebrate fauna of the  Freshwater flows must be sufficient to maintain transitions from requirements for floodplain Lower Test Valley SSSI and assess this in fresh to brackish and fully saline habitats both within the flood invertebrates, and use these to Impact on the floodplain The report states that 2 x samples per season (spring terms of its habitat requirements. (2) Identify plain and along the main freshwater fed water courses, in assess the effect of changes in wetlands including flooding and autumn) are needed at established sites u/s and the ways in which freshwater flows influence particular the Middle River. Wetland water level and water tables Floodplain period and flow regime. Tool to deliver flow d/s of the intake, identified to species level. EA the range and wetland habitats of importance  The period and extent of flood plain inundation needs to be macroinvertebrate created by different abstraction Invertebrates Flows to the Middle River thresholds believe existing/historic dataset not considered to invertebrates within the flood plain including maintained and allowed to migrate inland in the face of sea level population scenarios in areas hydrologically are included in this robust enough for use due to perceived assessments of flooding period and flow rise. linked to the Testwood assessment methodological issues. regime. Flows to the Middle River are included  abstraction. We will also assess Flow velocities needs to be maintained in terms of both the in this assessment and integrated into the the effect of water level control frequency and duration of peak flows and summer low flows. requirements for fish and in-channel structures on preferred invertebrate communities." conditions.

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The impact on intertidal habitat can be assessed in terms of the The report states an assessment needs to cover The report requests an assessment of the change in flow volume entering impact from abstraction on surface water flooding, impact of abstraction on the intrusion of the tidal reaches in terms of the groundwater levels and soil moisture in the  No reduction in the extent of intertidal mudflat habitat; The impact on the intrusion seawater into Southampton Water and the change in frequency, duration, floodplain. Understanding of how abstraction might  No decrease in mudflat infaunal biodiversity and associated SPA of seawater into Location of the mixing lower Test. This could be done by monitoring magnitude and timing. This was affect the availability of flows into the network of Intertidal bird populations; Southampton Water and the zone, or key indicator the location of the mixing zone or the location assessed as part of the Habitats n/a floodplain ditches. Understanding of how abstraction Mudflats  No decrease in the supply of organic material from the River Test lower Test, and on the species, mudflat of key indicator species such as fucoid Directive Review of Consents for could affect water levels within the network of ditches into Southampton supply of organic carbon to carbon levels seaweeds. Also, an assessment of increased the Both the Solent Maritime in the floodplain. Assessment of the vegetation  Southampton Water abstraction on the supply of organic carbon to SAC and Solent and Water. communities of the floodplain (including Southampton Water is needed i.e. monitor Southampton Water SPA were aquatic/wetland brackish and saline and other semi- carbon levels in the mudflats subject to an assessment, and natural communities). as is not considered further within the NEP investigation.

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1.5. Abstraction

1.5.1. Introduction

There are two abstraction licences in the Lower Test: one held by Nursling Fish Farm and one held by Southern Water Services at Testwood. The Nursling Fish Farm has a licence to abstract water from the Great Test for non-consumptive fish farming. The fish farm has a maximum daily licence of 0.53 m3/s (45.5 Ml/d) (since 1990), but with no requirement to measure discharges. Returns from 2001–2008 suggest an average flow of 0.15 m3/s (13 Ml/d). Gauged flow data from 1983 to 1991 indicate flows in the range of 0.58 to 1.16 m3/s (50 to 100 Ml/d). The returning water from Nursling Fish Farm can re-enter the Great Test in several different places: either directly downstream of the Fish Farm back into the River Test upstream of the Testwood abstraction, or via a more indirect route entering the River Test downstream of the Blackwater confluence. It is believed that in recent years the location of the returning water has changed, although exactly when this occurred is unknown. Given this uncertainty, it has been agreed that the Nursling Fish Farm abstraction will be considered as wholly returning to the Great Test downstream of the Blackwater confluence. This will represent a precautionary position with regard to river volume upstream of the Testwood abstraction for the NEP investigation. Southern Water Services has a licence to abstract water at Testwood for public water supply. The abstracted water at Testwood supplies water to Hampshire and the Isle of Wight. Note that two different units for flow are used in this report. This is because studies associated with water resources tend to use the unit of Ml/d (mega litres per day), whereas hydrological and environmental studies use m3/sec, which is also expressed as „cumecs‟. 1 Ml/d is equivalent to 0.1157 m3/sec; 1 m3/s is equivalent to 86.4 Ml/d.

1.5.2. Testwood Public Water Supply

Southern Water Services (SWS)‟s Testwood water supply works (WSW) abstracts from the Lower River Test. SWS‟s abstraction licence for the Testwood WSW (no. 11/42/18.16/546) on the River Test authorises abstraction at a peak rate of 1.58 m3/s (136.38 Ml/d) up to an annual total of 49,915,080 m3 (equivalent to 366 days at the peak rate). Although originally designed to treat the full licensed capacity, the development of more stringent standards for treated potable water over the last 10–15 years means that the effective capacity of the Testwood works capable of meeting current drinking water standards has reduced, and is now estimated to be in the order of 1.22 m3/s or 105 Ml/d.

1.5.2.1. The Minimum Residual Flow (MRF) condition The abstraction is subject to a flow constraint known as a Minimum Residual Flow (MRF) condition; the Testwood abstraction licence states that abstraction should not cause flows, downstream of the confluence with the River Blackwater, to reduce below 1.05 m3/s (90.72 Ml/d). The location of the MRF is located where the Great Test enters the Lower Test Valley SSSI: approximately 600 m downstream of Testwood Bridge, and approximately 500 m downstream of the confluence of the Blackwater. The computation of the MRF is stated on the licence as follows: “The authority must cease or reduce the rate of abstraction hereby authorised so as to not cause either the flow in the river Test d/s of the Testwood Pumping Station intake as measured at SU 359 150 or the aggregate of; the flow in the River Blackwater as measured at the Ower GS at SU 328 175, the flow in the

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1.5.2.2. The Testwood abstraction trend over the study period For the purposes of the NEP investigation, a time series which represents the water taken from the River at Testwood was agreed with the Steering Group members. Appendix 1.5.1 details the approach that was taken, and Figure 1.5.1 presents the agreed time series covering January 1995 to December 2011. Figure 1.5.2 shows the agreed flow time series for the three abstraction scenarios at Testwood Gauging Station.

Figure 1.5.3 shows the same information for the MRF location, and also shows the MRF volume, and it can be seen that abstraction does not cause flows to dip below the MRF volume (1.05 m3/s, 90.72 Ml/d) over the periods shown (1996–2011).

Table 1.5.1 present summary statistics about the volumes of water abstracted for the entire time period and also the period of May to December as these are the months for which fish count data is available. The monthly grouping of March to May, and June to February are also presented to give context against other periods of the year.

Table 1.5.2 presents annual volume totals and daily average, minimum and maximum for each year and Figure 1.5.4 presents the same information graphically. Figures 1.5.5 to 1.5.6 present flow duration curves for different abstraction scenarios: both at Testwood GS and at the MRF location. Figure 1.5.7 and 1.5.8 present the abstraction volume taken as a proportion of naturalised flow, for Testwood GS and the MRF location respectively.

Over the 16 year period presented in the charts (January 1996 to end of 2011), the average historic abstraction is approximately 0.69 m3/s (60 Ml/d), which is about 44% of the daily licence. In summer months the average is closer to 0.71 m3/s (61 Ml/d) and in the winter months it is closer to 0.65 m3/s (56 Ml/d). On rare occasions (18 days in the last 16 years) peak abstraction rises above 1.16 m3/s (100 Ml/d) and on 2 days in that period it rose above 1.39 m3/s (120 Ml/d).

For historic abstraction, the mean percentage abstracted relative to naturalised flow at Testwood GS is 11%; the median is 9% with extreme values of 0% and 49% over the study period (1996–2011). Under the Fully Licensed scenario, the mean percentage abstracted relative to naturalised flow at Testwood GS is 25%; the median is 22% with extreme values of 0% and 84%. The percentage of abstraction at the MRF location is lower than at Testwood GS due to the Blackwater, and the Nursling Fish Farm abstracted volume re-entering the Main Test between these two locations. For the MRF location, the mean percentage of historic abstraction relative to naturalised flow is 9%; the median is 8% with extreme values of 0% and 30%. Under the Fully Licensed scenario, the mean percentage abstracted relative to naturalised flow is 19%; the median is 17% with extreme values of 0% and 52%.

Section 5.2 presents an assessment of the effect of the different abstraction scenarios upon river flow, velocity and water levels.

3 NB: 91,000 m3 per day is equivalent to 1.05 m3/s or 88.83 Ml/d

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Table 1.5.1 Summary statistics for the Testwood PWS abstraction

Whole dataset Jan to April May to Dec March to May June to Feb m3/s (Ml/d) m3/s (Ml/d) m3/s (Ml/d) m3/s (Ml/d) m3/s (Ml/d) Average abstraction 0.69 0.65 0.70 0.69 0.70 (60) (56) (60) (60) (60) Maximum abstraction 1.55 1.25 1.55 1.55 1.33 (134) (108) (134) (134) (115) Minimum abstraction 0.00 0.00 0.00 0.16 0.00 (0) (0) (0.00) (13) (0)

Table 1.5.2 Annual statistics for the Testwood PWS abstraction

Fully Fully Historic licensed Daily Daily Daily Historic licensed Daily Daily Daily volume volume average min max volume volume average min max Year (Ml/a) (Ml/a) (Ml/d) (Ml/d) (Ml/d) (m3) (m3) (m3/s) (m3/s) (m3/s) 1996 23,246 49,915 64 0 94 23,245,793 49,915,080 0.74 0.00 1.09 1997 25,288 49,915 69 30 115 25,288,475 49,915,080 0.80 0.34 1.33 1998 25,793 49,915 71 19 134 25,793,068 49,915,080 0.82 0.22 1.55 1999 23,547 49,915 65 7 108 23,547,391 49,915,080 0.75 0.08 1.25 2000 20,830 49,915 57 0 95 20,829,601 49,915,080 0.66 0.00 1.10 2001 19,383 49,915 53 2 94 19,383,261 49,915,080 0.61 0.02 1.09 2002 23,365 49,915 64 40 92 23,365,498 49,915,080 0.74 0.46 1.07 2003 21,214 49,915 58 23 89 21,213,816 49,915,080 0.67 0.27 1.03 2004 21,829 49,915 60 20 108 21,829,441 49,915,080 0.69 0.23 1.25 2005 21,935 49,915 60 25 105 21,934,516 49,915,080 0.70 0.29 1.22 2006 19,909 49,915 55 29 82 19,908,766 49,915,080 0.63 0.34 0.95 2007 21,712 49,915 59 36 73 21,711,953 49,915,080 0.69 0.42 0.84 2008 19,660 49,915 54 0 69 19,660,186 49,915,080 0.62 0.00 0.80 2009 19,446 49,915 53 13 76 19,445,801 49,915,080 0.62 0.15 0.87 2010 19,933 49,915 55 37 70 19,932,550 49,915,080 0.63 0.42 0.81 2011 20,552 49,915 56 26 76 20,552,494 49,915,080 0.65 0.31 0.88

1.5.2.3. The effect of fully licensed abstraction at extreme low flows Section 1.5.2.2 above looks at the historic abstraction record over the study period of 16 years. In order to look at a longer time frame, Section 3.5.1 details the results of work undertaken to assess the hydrological conditions of the study period in the context of a longer term flow record from Broadlands Gauging Station, as this data is available from 1957. The results show that the range of flows experienced within the NEP study period (1996–2011) spans high and low flows, and can be considered representative of the range of hydrological conditions recorded historically at Broadlands GS. See Section 3.5.1.1 for an assessment of periods of extremely low flows, looking back further in time before 1957 to 1920 using output from the Test and Itchen Groundwater Model.

1.6. The Water Framework Directive and Catchment Abstraction Management Strategy

1.6.1. Water Framework Directive

The European Water Framework Directive (WFD) came into UK legislation in 2003. Its purpose is to enhance the status and prevent further deterioration in the ecology of aquatic ecosystems and their associated wetlands and groundwater. It comprises a legal framework which includes measures to control abstraction pressures and promote efficient and sustainable water use. The WFD requires that water

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1.6.2. Catchment Abstraction Management Strategy

Abstraction licences and discharge consentsare issued and regulated by the Environment Agency. Water resource availability for current licences and applications for new licences are considered through the Environment Agency Catchment Abstraction Management Strategy (CAMS). CAMS are strategies for the management of water resources at a local level, and seek to balance the water needs of abstractors, other water users and the aquatic environment. CAMS is one of the main vehicles used by the Environment Agency for managing abstraction. Whereas CAMS initially focused mainly on abstraction pressures, WFD seeks to identify all significant pressures on

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1.6.3. Environmental Flow Indicators

Environmental Flow Indicators (EFIs) are used by the Environment Agency as a flow screening threshold for the purposes of:  Assessing the availability of water resources for abstraction;  Informing abstraction licensing strategy;  Determining conditions to be imposed on new abstraction licences (i.e. Hands-Off Flows); and  Indicating where flow pressure may compromise WFD ecological status. EFIs are the adaptation of the flow screening standards proposed by the UK Technical Advisory Group (UKTAG) for use in the Environment Agency‟s existing regulatory abstraction system. The classification of ecological status for surface water bodies under the WFD is based on the assessment of four quality elements. These four elements are:  biological quality – which provides the ultimate determination of ecological status;  physico-chemical quality;  specific pollutants; and  hydromorphological4 quality – which only requires explicit consideration in the classification at high ecological status. Below this level, hydromorphology plays a supporting role – being required to provide conditions that support the values specified for the biological quality. The hydrological regime is a component of the hydromorphological quality element. While the ecology might be expected to respond to habitat quantity measures such as water depth and velocity, the most commonly available and most readily measurable parameter of the hydrological regime is flow. Flow screening standards to inform WFD resource assessment across the UK have been reported by UKTAG (2006) based on research carried out for SNIFFER (projects WFD48 for rivers and lakes, WFD82 for regulated rivers and WFD83 for estuaries). At high ecological status, the quantity and dynamics of flow, and the resultant connection to groundwater, must reflect totally, or nearly totally, undisturbed (i.e. natural) conditions. Simple pressure screening tests have been carried out to map where the hydrology is „nearly pristine‟. To protect this status will require a more stringent regulatory regime than is generally required elsewhere. The aim of the Water Framework Directive is to achieve a minimum of good ecological status by 2015. At good status the hydrological regime is considered to be a „supporting element‟. This means that the hydrological regime must not compromise the achievement of good status in the biological quality element. The WFD provides no absolute definition of what good status hydrological regime is, except to say that it must not be a factor in the failure of the biology to achieve good ecological status.

4 Hydromorphology is a term that has been created for the Water Framework Directive but it has been given a new and specific meaning which is 'the hydrological and geomorphological elements and processes of waterbody systems' (i.e. Lakes, Rivers, Transitional Waters and Coasts). For rivers, the definition in Annex V S1.1 of the Directive covers the following: quantity and dynamics of water flow; connection to groundwater bodies; River continuity; Morphological conditions; river depth and width variation; structure and substrate of the river bed; and structure of the riparian zone.

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1.6.3.1. Abstraction Sensitivity Bands The EFIs are used by the Environment Agency as a flow screening threshold and indicate where flow pressure may compromise Water Framework Directive (WFD) ecological status. Setting the appropriate EFI threshold is influenced by the ascribed Abstraction Sensitivity Bands (ASBs) for the watercourse. Based on physical catchment characteristics and expected fish and macro-invertebrate communities, WFD river water bodies have each been ascribed one of three ASBs, each with an associated EFI set as different proportions of the natural flow regime. The ascribed ASB reflects the expected sensitivity of the ecology to changes in flow given the physical character of the river reach and upstream catchment. The overall ASB is determined with reference to three component sensitivities in relation to physical typology, invertebrates and fish. A summary of the typologies are provided in Table 1.6.1.

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Table 1.6.1 Summary of Abstraction Sensitivity Band typologies

ASB elements Summary The ASB score is based on a range of physical, environmental and geographical variables. Physical Generally, the flatter the catchment, the lower the ASB scores. The River Invertebrate Classification Tool is used to predict the type of macro-invertebrate Macro communities expected from level dependent fish communities (ASB 1) to flow dependent invertebrates communities (ASB 3). The Fisheries Classification Scheme 2 model is used to predict what fish community would be expected for a given river type (defined by the environmental variables and geographic location) Fish under reference conditions (i.e. with the pressure variables set to zero). The fish communities range from level dependent fish species (ASB 1) to flow dependent fish species (ASB 3).

Table 1.6.2 EFI Compliance and non-compliance percentages of Qn95

Not adequate to Flow adequate to Flow not adequate to support GES – Abstraction support GES – support GES Low Confidence Sensitivity Band High Confidence (ASB) Compliant with Non-compliant Non-compliant Non-compliant EFI Band 1 Band 2 Band 3 <10% lower than <35% lower than <60% lower than >60% lower than High (3) natural flow natural flow natural flow natural flow <15% lower than <40% lower than <65% lower than >65% lower than Moderate (2)* natural flow natural flow natural flow natural flow <20% lower than <45% lower than <70% lower than >70% lower than Low (1) natural flow natural flow natural flow natural flow *The study reach of the Lower Test NEP investigation has been identified by the Environment Agency as having moderate sensitivity, with an Abstraction Sensitivity Band (ASB) of 2 – see Section 7.1.1 for more details.

1.6.3.2. CAMS-2 AP16 River Test Total (Great & Little Test) The River Test is considered within the Test and Itchen CAMS, the results of which were last published in 2006 (Environment Agency, 2006a). The further development of the CAMS approach to support the WFD (see previous sections) means that the study reach for the Lower Test NEP Investigation is located within Assessment Point (AP) 16 (Environment Agency, 2009c) as shown in Figure 1.6.2. In CAMS-1, Assessment Point AP17 was located immediately on the Great Test at Testwood. In CAMS-2, this AP has been closed, and the catchment it covered has been subsumed into “AP16 Test Total” (Environment Agency 2009c). AP16 River Test Total (Great & Little Test) is located at the furthest downstream point of the River Test at SU 3680 1369. The AP‟s catchment encompasses the River Test catchment downstream from Timsbury and includes the Blackwater, Great and Little Test channels, covering 242 km2. There is no gauging station at the AP16 Test Total assessment point, and so the Environment Agency estimate historic and naturalised flow at AP16 using data from the upstream gauging stations, comprising Testwood GS on the Great Test, Conagar Bridge on the Little Test, with flow statistics for the Blackwater. Section 7.1.1 details the outcomes of the CAMS-2 and EFIs approach to the Lower River Test.

1.6.3.3. The WFD South East River Basin Management Plan The South East River Basin Management Plan was reviewed to establish the current status of the water bodies within the study area.

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Mitigation measure Status Alter timing of dredging/disposal In place Reduce sediment re-suspension In place Reduce impact of dredging In Place Prepare a dredging / disposal strategy In Place Avoid the need to dredge (e.g. minimise under-keel clearance; use fluid mud navigation; flow In Place manipulation or training works) Structures or other mechanisms in place and managed to enable fish to access waters In Place upstream and downstream of the impounding works Indirect / offsite mitigation (offsetting measures) Not In Place Operational and structural changes to locks, sluices, weirs, beach control, etc Not In Place Preserve and where possible enhance ecological value of marginal aquatic habitat, banks Not In Place and riparian zone Source: Environment Agency (2009b)

1.6.4. SSSI Conservation Objectives and Flow Targets

SSSIs are notified by Natural England because of specific biological or geological features and Conservation Objectives define the desired state for each site in terms of the features for which they have been designated. When these features are being managed in a way which maintains their nature conservation value, then they are said to be in „favourable condition‟. The Conservation Objectives and definitions of favourable condition for features on the SSSI should inform the scope and nature of any assessment into issues at the site. The definitions of favourable condition for features on the SSSI comprise a series of measures and targets for the site, including targets for river flow. These measures of condition are derived from a set of generic guidance on favourable condition prepared by NE specialists, and have been tailored by local staff to reflect the particular characteristics and site-specific circumstances of individual sites. Quality Assurance has ensured that such site-specific tailoring remains within a nationally consistent set of standards. The Flow Target set by Natural England for Unit 91 (see Section 2.1.1.1) of the River Test SSSI is of relevance to this investigation. Table 1.6.5 sets out the Flow Targets: of particular relevance are the quantified flow thresholds specified in relation to daily naturalised flows as follows:  When the river has high to average flow (Q1 to Q50) abstraction must not exceed 20% of naturalised flows;  When the river has average to low (Qn50 to Qn95) abstraction must not exceed 15% of naturalised flows; and  When the river has low to very low flow (Qn95 to Qn100) abstraction must not exceed 10% to 15% of naturalised flows. As stated above, these Conservation Objectives are derived from a set of generic guidance on favourable condition: these flow targets relate to Chalk Rivers (they are derived from data from rivers of all sizes across the UK) and not specifically generated for the River Test. They have been devised by English Nature, now Natural England, to indicate acceptable deviations from naturalised flow across the whole flow regime, such that abstraction from a river does not impact upon the range of habitat factors of critical importance to characteristic flora and fauna (including macrophytes, invertebrates and fish), and to protect the most sensitive reaches of a river within the natural constraints dictated by the river type. Where habitat diversity is artificially impaired by modifications for example, it is the expectation under the Countryside and Rights of Way Act 2000 that this would be improved. In other words, the impact of abstraction on the natural flow regime must be considered in the absence of such modifications. Natural England states that in some circumstances, local investigations of habitat-flow relationships may indicate that a less stringent threshold may be acceptable for a specified river reach. Any proposal to modify the SSSI flow target would need to be properly justified, and provide robust evidence to show that the whole

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Table 1.6.5 The Natural England Conservation Objective Flow Target for the River Test SSSI

Attribute term in Measure Site-specific Targets Comments guidance

Flow regime should be River flow affects a range of habitat factors of characteristic of the river. critical importance to characteristic flora and fauna, including current velocity, water depth, Chalk rivers fall in the Moderate wetted area, substrate quality, dissolved RAM Environmental Weighting oxygen levels and water temperature. The band. maintenance of both flushing flows and Data on gauged seasonal base flows, based on natural and naturalised Levels of abstraction should not hydrological processes, is vital. flows, flow exceed the figures below in Habitat accretion relation to daily naturalised flows. Detailed and ecological robust investigations functioning: methods, and  High to average flow (Q1 to Q50): of habitat-flow relationships may indicate that water flow the Resource abstraction should not exceed a more or less stringent threshold may be Assessment 20% appropriate for a specified reach; – in these Method (RAM) instances generic targets may be over-ridden Framework.  Average to low (Qn50 t o Qn95) (guidance on this process is available). abstraction should not exceed 15% Naturalised flow is defined as the flow in the absence of abstractions and discharges. The  Low to very low flow (Qn95 to generic targets vary according to the specific Qn100) abstraction should not sensitivity of the reach type, with large exceed 10% lowland rivers having somewhat lower sensitivity than headwater streams. Any Ecological flow criteria already laid relaxation of generic targets on regulated Habitat down for the river (e.g. for SSSI rivers should relate to the desirability functioning: As above passage of migrating salmon) and ecological sustainability of regulating water flow should also be complied with. structures. The availability and reliability of data is Habitat There should be no obvious Field patchy – long-term gauged data can be used functioning: problems with water availability observations until adequate naturalised data become water flow within the monitoring unit. available, although the impact of abstractions on historical flow records should be considered.

Habitat Headwater sections are particularly Field Springs in aquifer-fed rivers functioning: vulnerable to abstraction, and downstream observations should be maintained. water flow migration of perennial heads, other than in drought conditions, is a sign of unfavourable condition.

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2.1. Nature conservation designations

The River Test SSSI is the prime habitat of concern to this NEP investigation. However there are other designated areas adjacent to the River, see Table 2.1.1 and Figure 2.1.1, which are discussed in this report. Adjacent to the River Test SSSI is the Lower Test Valley SSSI, which is itself a component of internationally designated areas. All of the Lower Test Valley SSSI lies within the Solent and Southampton Water SPA and Ramsar site, and parts of the SSSI are covered by the Solent Maritime SAC. This section details the designated habitats in the vicinity of the study area, and other assessment work of relevance to the NEP.

Table 2.1.1 The ecological designations in or adjacent to the Lower Test

Level Designation

National River Test SSSI

National Lower Test Valley SSSI

International Solent Maritime Special Area of Conservation (SAC)

International Solent and Southampton Water Special Protection Area (SPA)

International Solent and Southampton Water Ramsar site

2.1.1. The River Test

The River Test is a classic chalk stream, located in the county of Hampshire, and adjacent to the River Itchen. The River Test rises in Overton, near Basingstoke and flows to Nursling near Southampton, and enters Southampton Water. The river has been subject to much alteration and modification in the past and is currently heavily managed for fisheries. The river generally has no natural floodplain; rather it has a system of man-made water meadows historically used to encourage grass growth (for gazing) by moving river water over it. Historical modifications to the river over the centuries have created a river with a multitude of channels. The modifications have included alterations (realignment and deepening) to channels and carriers for land drainage and navigation, abstraction of water for irrigation, the construction of sluice systems and the flooding of water meadows. Leats were constructed to channel water from the river toward mills that were used for various industries including tanning and flour milling. The construction of sluice systems and creation of channels for water meadows, water mills and navigation over the centuries has considerably modified the river and water level management is extensive. Drainage activities in the 1940s involved the dredging of the river channel to allow arable production on the floodplain in certain locations. Current commercial activities that occur on the river include game fishing, water abstraction for fish farming and public water supply, and the discharge of treated effluent from wastewater treatment works. Figure 2.1.2 shows the River Test SSSI, which covers approximately 50 km of river channel, and an area of 443 ha. The River Test SSSI citation is presented in Appendix 2.1.1.

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Table 2.1.2 Summary Condition Assessment for Unit 91 of the River Test SSSI

River Test Condition Condition assessment comment Reason for adverse SSSI Unit assessment condition

91 Unfavourable Doesn't comply with flow target; Doesn't comply Inappropriate weirs dams and no change with water quality chemical targets; Doesn't other structures, Invasive comply with some aspects of channel and freshwater species, Siltation, banks habitat structure; topmouth gudgeon and Water pollution – barbel present agriculture/run off

Source: the Natural England website http://www.sssi.naturalengland.org.uk/Special/sssi/index.cfm

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Table 2.1.3 Detailed Condition Assessment for Unit 91 of the River Test SSSI

River Test SSSI condition assessment form (date: 27 March 2006)

Attribute Classification E2 SSSI unit no. 91 1 Habitat function: flow 1.1 compliance with flow target X 1.2 recorded hydrological problems 2 Habitat function: water quality 2.1 observed turbidity 2.2 compliance with biological class a 2.3 compliance with chemical class b 2.4 compliance with ammonia target 2.5 compliance with suspended solids target 2.6 compliance with phosphorus target X 3 Habitat structure: substrate 3.1 observed surface siltation F 4 Habitat structure: channel and banks 4.1 compliance with river planform target 4.2 compliance with river profile target (RHS transect data) U 4.3 compliance with river profile target (RHS sweep-up data) 4.4 compliance with river bank vegetation target F 4.5 compliance with riparian zone target F 4.6 compliance with HMS target U 5 Plant community 5.1 compliance with species composition target F 5.2 compliance with loss of species target F 5.3 compliance with abundant species target F 5.4 compliance with reproduction target F 6 Negative indicators (biological disturbance) 6.1 compliance with native macrophyte species target F 6.2 compliance with naturalness of macrophytes target F 6.3 compliance with „other organisms‟ Barbel present 7 Indicators of local distinctiveness 7.1 rare species Oenanthe fluviatilis Otter Water Vole 7.2 other site-specific aspects Bullhead  Brook lamprey  Salmon  8 Aspects of environmental disturbance 8.1 note any Fish stocking 9 Overall condition of unit (F, R, U, D) U Where:  = complies with target / species present, X =does not comply F = Favourable, U = Unfavourable, UD = Unfavourable declining, n/a = not applicable, due to use of new survey site this year Completed by English Nature Conservation Officer Alison Graham-Smith. Shaded portion comprises results of field survey in July 2005, input from contractor‟s form Source: Natural England

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Table 2.1.4 Remedies identified for Unit 91 of the River Test SSSI

Adverse Adverse Condition Organisation Financial Condition Remedy Description Organisation Name Remedy Status Comments Description Type Year Status Environment Environment Agency – Remedy Remedied Inappropriate Water Levels Water level management plan 2010/11 Agency Hampshire And Isle Of Wight Underway/Complete Inappropriate Weirs Dams Environment Environment Agency – Live River restoration project Remedy Agreed 2012/13 And Other Structures Agency Hampshire And Isle Of Wight Inappropriate Weirs Dams Natural Live River restoration project Natural England Remedy Agreed 2012/13 And Other Structures England Agree and implement an invasive species control policy with EA, EN and others, to address presence of topmouth Invasive species control Environment Environment Agency – Live Invasive Freshwater Species Remedy Agreed 2011/12 gudgeon and barbel. (Given their programme Agency Hampshire And Isle Of Wight potential to cause ecological damage through the spread of disease and competition for habitat.) Discharge/ PPC consent – Environment Environment Agency – Remedy Underway/ Live Siltation 2009/10 revoke/amend AMP 3/4 Agency Hampshire And Isle Of Wight Complete Natural Remedy Underway/ Live Siltation Facilitate RLR Registration Natural England 2010/11 England Complete Natural Live Siltation HLS Natural England Remedy Agreed 2011/12 England Investigation to examine effects of Implement PR09/AMP5 Water Remedy Underway/ Remedied Water Abstraction Southern Water Services Ltd 2009/10 increasing abstraction to full licensed investigation Companies Complete amount. Water Pollution – National Defra DWPA Remedy Underway/ Live Defra Defra Water Quality 2007/08 Agriculture/Run Off strategy Complete Water Pollution – Environment Environment Agency – Remedy Live Diffuse Water Pollution Plan 2010/11 Agriculture/Run Off Agency Hampshire And Isle Of Wight Underway/Complete Water Pollution – Natural Remedy Live CSF Delivery Initiative Natural England 2010/11 Agriculture/Run Off England Underway/Complete Water Pollution – Natural Remedy Live Diffuse Water Pollution Plan Natural England 2010/11 Agriculture/Run Off England Underway/Complete Water Pollution – Natural Live ELS Natural England Remedy Agreed 2011/12 Agriculture/Run Off England Discharge/ PPC consent – Environment Environment Agency – Remedy Remedied Water Pollution – Discharge 2009/10 revoke/amend AMP 3/4 Agency Hampshire And Isle Of Wight Underway/Complete Water Remedy Remedied Water Pollution – Discharge Implement AMP scheme Southern Water Services Ltd 2009/10 Companies Underway/Complete Last condition assessment for unit 91 = 28/03/06, carried out by Alison Graham-Smith Source: Provided by Natural England. Remedies Detailed Report – River Test SSSI, Unit 91. Downloaded from ENSIS 24-05-11

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2.1.2. Lower Test Valley SSSI

Figure 2.1.1 shows the location of the Lower Test Valley SSSI, which covers an area approximately 139 ha in extent. The Lower Test Valley SSSI is broken down into eight component units, classed as littoral sediment (three units), fen, marsh and swamp (two units) and lowland neutral grassland (three units). The SSSI citation (Appendix 2.1.2) states that the site is located at the upper estuary of the River Test and exhibits a gradation from salt through brackish to freshwater conditions. The site includes one of the most extensive reed Phragmites beds on the south coast, with flanking unimproved meadowland intersected by numerous tidal creeks flooded on high water spring tides. Saltmarsh habitat to the south supports a varied flora with several species characteristic of salt marsh habitat. Above the limit of tidal influence are extensive unimproved neutral meadows containing several plants now rather uncommonly found owing to modern intensive agricultural methods. Over 450 species of flowering plants have been recorded for the site as a whole. The SSSI unit condition assessments were last surveyed in July 2008 and shows that all the units are described as being in favourable condition.

2.1.3. Solent Maritime Special Area of Conservation (SAC)

The River Test SSSI flows into, and parts of the Lower Test Valley Marshes are partly covered by the Solent Maritime SAC, shown in Figure 2.1.1. Details of the Solent Maritime SAC are as presented in Table 2.1.5. The upstream boundary of the Solent Maritime SAC reflects the general upper limit of transitional grassland/ saltmarsh communities. Although there are small areas of mud along channels at low tide, Atlantic Salt Meadow (ASM) is the only SAC feature represented in the Lower Test Marshes component of the SAC. Vegetation surveys of the Lower Test Marshes identify this community as SM16 Juncus gerardii saltmarsh habitat, containing „a significant extent in the context of the SAC as a whole‟ according to the designation.

Table 2.1.5 Details of the Solent Maritime SAC

Criteria Detail Annex I habitats that are a 1130 Estuaries primary reason for selection of 1320 Spartina swards (Spartinion maritimae) this site 1330 Atlantic salt meadows (Glauco-Puccinellietalia maritimae). 1110 Sandbanks which are slightly covered by sea water all the time 1140 Mudflats and sandflats not covered by seawater at low tide Annex I habitats present as a 1150 Coastal lagoons (Priority feature) qualifying feature, but not a 1210 Annual vegetation of drift lines primary reason for selection of 1220 Perennial vegetation of stony banks this site 1310 Salicornia and other annuals colonising mud and sand 2120 Shifting dunes along the shoreline with Ammophila arenaria (`white dunes`) Annex II species that are a primary reason for selection of Not applicable. this site Annex II species present as a qualifying feature, but not a 1016 Desmoulin`s whorl snail Vertigo moulinsiana primary reason for site selection Source: the JNCC website: http://jncc.defra.gov.uk/protectedsites/sacselection/sac.asp?EUcode=UK0030059

2.1.4. Solent and Southampton Water Special Protection Area (SPA)

The Lower Test Valley is designated as part of the Solent and Southampton Water SPA (Figure 2.1.1). The Solent and Southampton Water SPA qualifies under Article 4.1 of the Directive (79/409/EEC) by supporting populations of European importance of the breeding species listed on Annex I of the Directive. The site also qualifies under Article 4.2 of the Directive in supporting populations of European importance of the migratory species. Details of the qualifying features are presented in Table 2.1.6.

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The Lower Test Valley marshes are a component part of the Solent and Southampton Water Ramsar site (Figure 2.1.1). A summary of the four Ramsar-qualifying features (taken from the Ramsar Information Sheet, Version 3 June 2008) is presented in Table 2.1.7.

Table 2.1.6 Solent and Southampton Water SPA qualifying features

Criteria Detail

Article 4.1  Common Tern Sterna hirundo, 267 pairs representing at least 2.2% of the breeding population in During the Great Britain (5 year peak mean, 1993–1997) breeding  Little Tern Sterna albifrons, 49 pairs representing at least 2.0% of the breeding population in season Great Britain (5 year peak mean, 1993–1997)  Mediterranean Gull Larus melanocephalus, 2 pairs representing at least 20.0% of the breeding population in Great Britain (5 year peak mean, 1994–1998)  Roseate Tern Sterna dougallii, 2 pairs representing at least 3.3% of the breeding population in Great Britain (5 year peak mean, 1993–1997)  Sandwich Tern Sterna sandvicensis, 231 pairs representing at least 1.7% of the breeding population in Great Britain (5 year peak mean, 1993–1997)

Article 4.2 over  Black-tailed Godwit Limosa limosa islandica, 1,125 individuals representing at least 1.6% of the winter migratory wintering Iceland – breeding population (5 year peak mean, 1992/3–1996/7) species  Dark-bellied Brent Goose Branta bernicla bernicla, 7,506 individuals representing at least 2.5% of the wintering Western Siberia/Western Europe population (5 year peak mean, 1992/3–1996/7)  Ringed Plover Charadrius hiaticula, 552 individuals representing at least 1.1% of the wintering Europe/Northern Africa – wintering population (5 year peak mean, 1992/3–1996/7)  Teal Anas crecca, 4,400 individuals representing at least 1.1% of the wintering Northwestern Europe population (5 year peak mean, 1992/3–1996/7)

Assemblage The area qualifies under Article 4.2 of the Directive (79/409/EEC) by regularly supporting at least qualification: A 20,000 waterfowl wetland of Over winter, the area regularly supports 53,948 individual waterfowl (5 year peak mean 1991/2– international 1995/6) including: Gadwall Anas strepera, Teal Anas crecca, Ringed Plover Charadrius hiaticula, importance Black-tailed Godwit Limosa limosa islandica, Little Grebe Tachybaptus ruficollis, Great Crested Grebe Podiceps cristatus, Cormorant Phalacrocorax carbo, Dark-bellied Brent Goose Branta bernicla bernicla, Wigeon Anas penelope, Redshank Tringa totanus, Pintail Anas acuta, Shoveler Anas clypeata, Red-breasted Merganser Mergus serrator, Grey Plover Pluvialis squatarola, Lapwing Vanellus vanellus, Dunlin Calidris alpina alpina, Curlew Numenius arquata, Shelduck Tadorna tadorna.

Source: the JNCC website: http://jncc.defra.gov.uk/page-2037

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Table 2.1.7 Solent and Southampton Water Ramsar qualifying features

Ramsar Criterion Detail

The site is one of the few major sheltered channels between a substantial Criterion 1 (A representative, rare, or island and mainland in European waters, exhibiting an unusual strong unique example of a natural or near- double tidal flow and has long periods of slack water at high and low tide. It natural wetland type found within the includes many wetland habitats characteristic of the biogeographic region: appropriate bio-geographic region) saline lagoons, saltmarshes, estuaries, intertidal flats, shallow coastal waters, grazing marshes, reedbeds

Criterion 2 (it supports vulnerable, The site supports an important assemblage of rare plants and endangered, or critically endangered invertebrates. At least 33 British Red Data Book invertebrates and at least species or threatened ecological eight British Red Data Book plants are represented on site. communities)

Criterion 5 (It regularly supports Winter counts over five years (1998/99–2002/03) recorded a peak mean of 20,000 or more waterbirds) 51,343 waterfowl in the Solent and Southampton Water Ramsar site.

The following qualifying species/populations (as identified at designation) are recorded on the Ramsar Information Sheet: Spring/autumn peak counts: Ringed Plover Charaduris hiaticula 397 individuals, average of 1.2% of GB population (5 year peak mean 1998/9–2002/3) Criterion 6 (It regularly supports 1% of the individuals in a population of Winter peak counts one species or subspecies of Dark-bellied Brent Goose Branta bernicla 6456 individuals, representing waterbird) an average of 3% of the population (5 year peak mean 1998/9–2002/3) Eurasian Teal Anas crecca 5514 individuals, representing an average of 1.3% of the population (5 year peak mean 1998/9–2002/3) Black-tailed godwit Limosa limosa islandica 1240 individuals, representing an average of 3.5% of the population (5 year peak mean 1998/9–2002/3

Source: the JNCC website: http://jncc.defra.gov.uk/pdf/RIS/UK11063.pdf

2.1.6. Habitats Directive Review of Consents

The Environment Agency completed its Habitats Directive (HD) Regulations Review of Consents Stage 3 Appropriate Assessment in 2005. Both the Solent Maritime SAC and Solent and Southampton Water SPA were covered in that assessment. A summary of the HD investigation and its conclusions are presented below. The HD investigation is of relevance to this NEP as the effect of the Testwood abstraction on the SAC and SPA was examined. The Environment Agency has an obligation to undertake a review of consents under Regulation 50 of The Conservation (Natural Habitats, &c.) Regulations 1994 for Natura 2000 sites (i.e. SAC, SPA and Ramsar sites). The Review of Consents is undertaken in four stages: Stage 1 – All „relevant‟ permissions are identified: these include abstraction licences, discharge consents, Integrated Pollution Control (IPC) permits, radioactive substances (RSR) authorisations and waste management licences; Stage 2 – This stage assesses all identified relevant permissions to identify „likely significant effects‟. All those that were likely to have a significant effect on the designated site are further examined in Stage 3; Stage 3 – This stage comprises an assessment to see whether the Environment Agency permissions are having an adverse effect upon the integrity of the site. Each permission is assessed both alone

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2.1.6.1. Solent Maritime SAC Habitats Regulations (50) Review of Consents The Stage 3 Appropriate Assessment for the Solent Maritime SAC was completed in April 2005, and considered 189 water resource Environment Agency permissions. Pages 74–82 of the assessment consider the effects of abstractions in the catchment of the River Test on the component of the SAC corresponding to the Lower Test Valley SSSI. This part of the SAC is described as having „large areas of sub tidal sediment, which is unlikely to be affected by abstraction. Mudflat fringes the entire area with large patches of saltmarsh alongside the Test estuary. The site was considered to be in an unfavourable condition due to hyper-nitrification in Southampton Water and at Chichester and Langstone Harbours. This was not considered relevant to the consideration of abstraction licences on the Solent Maritime SAC. The main impact pathway between abstraction and the SAC component was given as follows: “The exposure of salt meadow to changes in fresh flows is mainly related to the dynamic interaction of fresh water flows and the degree of tidal inundation on various neap, spring, or surge tides. However, the system at Lower Test is unlikely to be sensitive even to moderate short term changes, because almost the whole of the area that qualifies as ASM is tidally inundated on at least a few occasions annually. The limiting condition would be when low summer flow combines with a surge tide. However, over time, and especially with sea level rise, there is potential for progressive change in community type if the average salinity increases. However, the degree of effect of reduced flows on upper marsh and transitional vegetation may be reduced by density effects, whereby the fresh water rides over salt water as the tide rises.” The Definition of Risk for Testwood was identified as Medium. This was computed as follows: Moderate level of abstraction × Medium level of vulnerability = Medium level of Risk

The Testwood SWS licence was one of only three licences that needed to be considered within the appropriate assessment following the risk based approach. The full list of licences in the Medium Risk category is:  18.14/479 Island Home Farm & Lone Barn Farm  18.16/442 Broadlands Estate  18.16/546 Testwood Intake The assessment concluded that, “Despite the sensitivity of saltmarsh to freshwater, the system at Lower Test Marshes is dynamic and can respond to changes in both sea level and freshwater inflow.” The Environment Agency concluded that:  Alone, each abstraction licence on the River Test can be shown to have no adverse effect on the integrity of the Solent Maritime SAC.  These abstraction licences are determined to be not adverse (alone), but in-combination are considered to be greater than trivial in terms of the risk they present to site integrity in combination with other abstraction licences across the „site‟. The Environment Agency concludes that in-combination the abstraction licences (18.14/479, 18.16/442, 18.16/546) on the River Test, cannot be shown to have no adverse effect on the integrity of the Solent Maritime SAC.

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Table 2.1.8 Sensitivity of the interest features within the Lower Test Marshes component of the SPA

Interest Features Notes

Internationally Mediterranean Gull, Important populations Sandwich Tern, Freshwater is not thought to be very important for these species of regularly occurring Common Tern, Little in this area Annex 1 species Tern, Roseate Tern,

These are not noted as being particularly prevalent in this area. Dark bellied Brent Freshwater only really used for bathing and preening and not Goose generally for feeding. Wet grassland may be important.

Flocks of Teal gather from August onwards around areas of Internationally saltmarsh in this area. Freshwater is used for preening. Teal important populations Teal „dabbling‟ ducks feed upon vegetation and seeds at water‟s edge of regularly occurring so saltmarsh habitat is likely to be important. They are also migratory species associated with freshwater/ brackish ponds

Ringed Plover Feed on mudflat areas and may be related to freshwater flows.

Black tailed godwits fly in around mid July and feed on inter-tidal Black Tailed Godwit mudflats

Internationally important Wintering waterfowl Shelduck are particularly concentrated on Eling Marsh with assemblage of assemblage redshank using the site as well. waterfowl

The assessment concluded that „The Lower Test Nature Reserve is a very important freshwater dominated wetland which birds appear to make great use of. The main effect on habitats for birds is thought to be management and to a lesser extent the amount of fresh water available. An assessment of saltmarsh suggests that this transitional habitat can move within the nature reserve and will be as affected by abstraction‟. The Environment Agency concluded that:  Alone, each abstraction licence on the River Test can be shown to have no adverse effect on the integrity of the Solent and Southampton Water SPA; and  In-combination, the abstraction licences on the River Test are greater than trivial in terms of the risk it presents to site integrity in-combination with other abstraction licences across the „site‟. The Agency

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2.1.6.3. Summary of the Habitats Directive Review of Consents In summary, the Environment Agency has completed the Habitats Directive Review of Consents for the Solent Maritime SAC and the Solent and Southampton Water SPA. Both assessments considered a large number of water resource permissions upon the designated sites of international importance. Of interest to this NEP investigation is the Testwood PWS abstraction that was included in the assessment.

For both the Solent and Southampton Water SPA and the Solent Maritime SAC, the Environment Agency concluded that the Testwood PWS abstraction alone can be shown to have no adverse effect on the integrity of the SPA and SAC. Whilst the Environment Agency concluded that in-combination with other licences the Testwood PWS abstraction cannot be shown to have no adverse effect on the integrity of the SPA and SAC, Testwood PWS abstraction license was subsequently affirmed as part of the Stage 4 Site Action Plan as part of the Habitats Directive Review of Consents. The Solent and Southampton Water Ramsar site should also have been subject to the same process outlined about for the Solent Maritime SAC and Solent and Southampton Water SPA. While Ramsar sites are not Natura 2000 sites, they are considered as such for the Habitat Directive process, and therefore should be subject to the same Review of Consents process. While it is not within the scope of the NEP investigation to undertake this process, an appraisal has been untaken to see if the conclusion for the SAC and SPA sites would also be applicable to the Ramsar site. IT has been determined that the qualifying features of the Ramsar site as the same as those for the SPA, therefore it is considered that, for the purposes of the Lower Test SSSI NEP investigation, the conclusion of the Appropriate Assessment for the Solent and Southampton Water SPA is also relevant for the Ramsar site.

2.2. Fisheries

In the time leading up to this investigation, the Environment Agency spent considerable time collating available data and reports and reviewing what it considered to be the key issues relating to the Lower River Test, in particular those issues that were potentially relevant to Southern Water‟s Testwood abstraction. As indicated in Section 1.2.2, its conclusions were set out in its report „Testwood Public Water Supply Abstraction Impact Investigation – Statement of Issues and Assessment‟ (Environment Agency, 2010a). Following discussion and review of the available data and reports with the EA, and submission of a Scoping Report on this NEP Investigation to the EA in June 2011, it was agreed that the primary focus of the fisheries assessment in the NEP investigation should be on the river‟s salmon population. Salmon are considered to be the most sensitive of the fish species present in the Lower River Test and the EA stated that if the habitat and flow regime is generally acceptable for salmon it is likely to be acceptable for the other fish species

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2.2.1. Salmon

With regard to the salmon population of the Lower River Test, the text within the box below is extracted directly from the EA report and sets out the principal issues relating to the salmon population and the specific concerns that this investigation needs to address with regard to the potential effects of the Testwood abstraction licence. Please refer to the original document (Environment Agency, 2010a) for the full text.

Status

Salmon have been performing below their conservation limit and management target for several decades. The conservation limit indicates the egg deposition each year below which the population is considered at significant risk and therefore, ideally, the population should not be allowed to fall below this limit. Over the long term, it is clear that salmon populations were much larger in the River Test in the decades preceding the 1970s as evidenced by the rod catches of over 1000 salmon per annum. This was followed by a steady decline in catches until the late 1980s when a sudden crash in angler catches occurred. This pattern is similar to that of other southern English salmon rivers suggesting a common effecting component. Figure 2.2.1 shows historic rod catches with Figure 2.2.2 showing nominal catches of salmon in four North Atlantic regions between 1960 and 2003. Since the crash of the late 1980s the River Test has demonstrated an ability to recover from adverse conditions and recently exceeded its conservation limit for the first time in nearly two decades. Key factors

This section summarises the key factors adversely affecting salmon in the lower Test or from which they may be at risk. It includes the action being taken to mitigate the effects and further actions that are planned or required. The Joint Nature Conservation Committee lists 20 threats and pressures on Atlantic salmon of which many are relevant on the lower River Test. These have been reduced to the following which are considered the most important factors relevant to the lower River Test. 1. Siltation of gravels Many studies have indicated that the spawning success of salmon may be affected by siltation of spawning gravels. Competition for oxygen with the natural breakdown of organic material and the physical “clogging” of substrate appears to be the main mechanisms by which the survival of salmon eggs is impaired. Studies in the early 1990s found that egg survival was low <25% and that there was a great deal of siltation and concretion in the southern chalk streams. At many sampling sites the survival rate of eggs placed in artificial redds was 0%. Using adult salmon population estimates in conjunction with estimates of salmon smolt numbers it is clear that there is a significant range in spawning success from one year to another. In some years over 20 smolts (one year old juveniles) are produced for each spawner. In other years only five smolts are produced per spawner. It also appears that incubation season (January to early May) river flow is associated with spawning success. Low flows are associated with higher spawning success and high flows with lower spawning success. It is suggested that the mobility of sediment in the river system during the incubation period is a key factor in determining that year‟s spawning success. Figure 2.2.3 and Figure 2.2.4 show spawning success in the lower Test measured against discharge during the incubation period and suspended solids for the years 1992–2006. A detailed study of these effects is being carried out on the River Itchen by Southampton University as well as catchment wide investigation by the Environment Agency. Catchment sensitive farming initiatives have taken over from landcare schemes aimed at reduction of soil loss from agricultural sources. The long term trend in suspended solids measured in the River Test is downward over the measured period of 30 years although there is considerable year to year variation. It is expected that incremental improvements in prevention of diffuse pollution will continue to be made as exemplified by the current project to reduce farm pollution on the Rivers Dun and Dever. The Environment Agency has also undertaken significant gravel cleaning and reinstatement works over the past two decades in an attempt to mitigate the spawning

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5. Climate change As reflected above, changes in the marine environment may impact marine survival of salmon although there seems little evidence for this locally. Significant correlations can be observed between the catches in local rivers and inshore water temperatures in the year of return, higher temperatures being associated with lower catches. Anglers often lament that high temperatures are not good for getting salmon to take a lure and so some of the noted association may be due to catchability. There is also a strong association of hot summers with low flows in rivers leading to difficulties in the interpretation of relationships. It has been noted that the marked upturn in inshore temperatures since the late 1980s was associated with a collapse in rod catches in many southern salmon rivers and in particular on the River Avon. Whilst a collapse in rod catches on the River Test was evident in the late 1980s it is quite clear that the salmon population has the potential to regenerate as is clear from achieving conservation limit compliance in 2008. This incremental upturn has occurred largely since 2001. In 2001 voluntary catch and release of rod caught salmon reached 100% thereby relieving significant pressure on the population. In addition the cohort returning as one sea-winter salmon in 2008 were a cohort to have unusually benefited from two successive generations of low discharge during incubation (also low sediment mobility) and consequently good spawning success (incubation in 2003 and 2006). Compared to the River Avon the water temperatures of the River Test appear to be relatively cool and stable which may account for the difference in impression of the effect from climate change on salmon migration into freshwater. 6. Disease Anasakis, Gyrodactylus

Atlantic salmon are susceptible to many viral and bacterial diseases of which some may be made worse by “pooling” of fish in close proximity. Some diseases such as furunculosis have been noted to be more prevalent when fish congregate in pools during warm weather and drought. “A common bacterial disease is Furunculosis. The furuncles or boils, which are usually fatal, are most likely to appear in wild fish in warmer months when river levels are low and fish collect in pools while waiting for more water to allow their upstream journey to continue.” Atlantic Salmon Trust Website, September 2009. 7. Competition and predation Stocked trout are often piscivarous and migrating salmon smolts are within the prey size range of most stocked trout. As the non-migratory trout angling season starts on the 3rd April and ends on the last day of October many trout are stocked during April when salmon are migrating to sea at a length of approximately 150 mm. Much of the risk of predation could be avoided if stocking was delayed until mid- May but this is thought to potentially affect commercially on trout angling. The densities of salmon juveniles in the River Test are generally low although some “hot spots” exist. Such “hot spots” can often be avoided by minimizing migration delay and the provision of fish passage facilities at obstructions. 8. River flow and abstraction It has long been recognized that salmon are positively rheotactic and not only turn to face a water current but actually swim towards a current at certain stages of the life cycle. In particular, adult salmon migrations have been associated with river discharge, water temperature and season. Given that abstractions have the potential to affect river discharge and water temperature the risk exists that abstraction could influence salmon migration. Salmon migration delay is sometimes portrayed as inconsequential but this may not be the case. As previously suggested, salmon spawning success is considered an important factor in the performance of the River Test salmon population. The mechanism by which spawning success can be affected is thought to be through the mobility of, primarily, agriculturally derived organic sediments. In general, the further up the catchment that samples are taken the lower the concentrations of suspended sediment that are observed. In addition, water temperatures tend to decrease the further upstream that measurements are taken. It is also thought that the effect of higher water temperatures on maturation and energy available for reproduction, those above the thermal optimum for salmon, are cumulative. Thus small increases in temperature experienced over a long time may lead to significant effects on reproduction. Such changes

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2.2.2. Sea Trout

David Solomon has provided the following account of sea trout in the River Test or this report.

Sea trout are the migratory form of the brown trout, and where they occur together they are freely inter-breeding fractions of a single population. A higher proportion of females tend to be migratory within the population. Sea trout tend to predominate in rivers where the growth opportunities are poor, and many chalk streams, where growth opportunities are generally good within the river, have few sea trout. Where they do occur in chalk streams they tend to be associated with the more acidic parts of the catchment where growth opportunities are less – for example many “Test” sea trout are believed to have originated from, and return to, the Blackwater. Rod catches of sea trout in the Test are of a similar order of magnitude to those of salmon, some hundreds each year. The great majority are caught at Testwood, with fair catches at Nursling; this is consistent with many returning to the Blackwater. Like salmon, they tend to remain in the lowermost reaches for most of the summer, ascending to their spawning grounds in the autumn. It is also likely that many of the sea trout that spend the summer around Testwood are in fact originating from, and subsequently return to, other smaller New Forest rivers such as the Avon Water, Lymington and Beaulieu. Sea trout have similar environmental requirements to salmon, though trout are generally less tolerant of high temperatures than salmon (Solomon and Lightfoot 2008). Any increases in water temperature are likely to impinge upon the wellbeing of the sea trout population sooner and to a greater extent than on salmon. Little is known of the influence of flow and water temperature on their migration.

2.3. Aquatic Macrophytes

The citation of the River Test SSSI describes the aquatic flora of the River Test SSSI along its length (see Appendix 2.1.1). For the purposes of the NEP investigation, attempts have been made to collate existing information on the aquatic macrophytes of the study area. Few records were uncovered, and it would appear that an aquatic macrophyte survey has not been undertaken in recent years. The following sections detail the survey information that has been obtained.

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2.3.1. River corridor survey, 1991

A River Corridor Survey (RCS) is a detailed survey of the aquatic macrophyte flora of the river. A RCS was undertaken in 1991 for the River Test (Griffiths, 1991): sections 169 to 171 cover the reach of the Great Test of interest to the NEP investigation. The results of the RCS survey for these sections are summarised in Table 2.3.1, with Figure 2.3.1 showing the locations of the sections. The detailed survey notes for sections 169 to 171 of the RCS are presented in Appendix 2.3.1.

2.3.2. Survey for the SSSI notification, 1995

Table 2.3.2 details the notes from a vegetation survey undertaken by Michael Liley for English Nature in 1995 at the time that the River Test SSSI was in the process of being designated. Only the reaches of interest to the NEP are discussed and Figure 2.3.2 shows the sections referred to in the table.

2.3.3. WLMP survey, 2006

For the River Test WLMP (2006b), a visual vegetation survey (due to access restrictions) of the channel of the Great Test (downstream of the Great/Little Test flow split) observed that it was dominated by species typical of lentic, sediment rich lowland rivers, with Schoenoplectus, Potamogeton lucens and Myriophyllum; Ranunculus was only found locally upstream of Nursling Mill in areas where gravel beds were exposed. A visual survey was also undertaken on the Little Test as well, which, in contrast showed good chalk stream flora, being generally dominated with Ranunculus, Zannichellia and Callitriche.

2.3.4. Habitat surveys of the Lower Test Valley, 1996, 2003

The vegetation of the Lower Test Valley SSSI has been surveyed by Neil Sanderson in 1996 and 2003 for the Hampshire Wildlife Trust. These surveys have been undertaken partly to monitor the influence of sea level rise and changes in the fresh/saline transition of vegetation communities within the SSSI. The surveys cover terrestrial and aquatic habitat, see also Section 2.7 and Figure 2.7.1.

2.3.5. Survey for the NEP, 2011

A survey of the Great Test was undertaken for this NEP assessment. The results of this survey and assessment of the effect of the Testwood abstraction is presented in Section 7.2.

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Table 2.3.2 Details of the aquatic macrophyte survey undertaken in 1995

Location Detail River is described as 18–20 m wide with a sluggish flow. The fenced banks have emergent fringes Point 11: River that are better developed on the left hand side (LHS). The left bank has emergent stands of reed between Southern canary grass Phalaris arundanacea and Sparganium (presumably Sparganium erectum). The Water Pumping channel is shown with bulrush Schoenoplecus lacustris. The right bank has emergent hairy willow Station and Boundary herb Epilobium hirsutum, hemp agrimony Eupatorium cannabinum, stinging nettle Urtica dioica and of Lower Test SSSI alder saplings. Shows gently shelving left bank to 0.5 m depth, centre of channel with bulrush Schoenoplectus lacustris. Right bank shown with local revetments. Both banks shown as fenced, with rough uncut Point 12: Cross buttercup rich grass on the left bank dominated by Holcus lanatus and Agrostis stolonifera with section Potentilla anserina and Cirsium arvense. The right bank has rank vegetation within Epilobium hirsutum and Urtica dioica. Straightened/canalised but fairly fast flowing over gravel. Main aquatic seems to be Sparganium Point 13 Back carrier emersum. Fenced along bank edge both sides. Little or no emergent fringe. Bank edges tall herb – at Southern Water dominated by Epilobium hirsutum, Urtica dioica and with some meadow sweet (Filipendula Pumping Station ulmaria). Straightened stretch ca. 300 m from confluence of Broadlands Lake drain to confluence of River Blackwater. Generally poor stretch of river with concrete reinforced banks and banks trampled by Point 15 cattle and horses. Marginal Sparganium erectum on the left bank and no recorded aquatic macrophytes. Point 16 150 m stretch downstream Banks disturbed by tree planting with rank ruderal vegetation (Epilobium hirsutum/Urtica dioica). from track and trout Channel shown as „wide and shallow‟ with no aquatic macrophytes. farm (now disused) Point 17 Main river A wide stretch of river (15–20 m). Strong flow below weir „giving high erosive power‟. „River has stretch at trout farm undercut steep and sandy banks – more cliffed in places. Holes & crevices, potentially good for ca 250 m from weir to birds such as kingfisher and sand martin?‟ track bridge Source: survey notes of Michael Liley for English Nature in 1995. Figure 2.3.2 shows the sections referred to in the table.

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A review of the River Test‟s aquatic macroinvertebrate diversity has been compiled by the Environment Agency in its reports for the Lower Test Project (2010a, 2011c) and a summary is presented here.

2.4.1. Main River Channel

The Environment Agency has collected aquatic macroinvertebrate data from a number of locations, as shown in Figure 2.4.1. Most of these sampling sites are only monitored on a three yearly basis, with the exception of the Broadlands and Testwood sites.

2.4.1.1. Review of historic sampling data

General Quality Assessment

The Environment Agency has used macro-invertebrate sampling, since 1989, to monitor water quality, which was known as the General Quality Assessment (GQA) scheme. Samples were collected using standard Environment Agency methodologies, based on a timed three minute kicksweep sample. One GQA biological sampling point, named Testwood, is located in the vicinity of the Southern Water Testwood abstraction intake. Two further sampling points were established by the Environment Agency in 2002, upstream and downstream of the intake. These were specifically placed to monitor the invertebrate communities present and detect any ecological changes due the abstraction, but the data can also be used to infer water quality. The Environment Agency (2010a) report that the River Test, as a whole, has scored amongst the highest biotic scores in the country (using EA data from 1987 onwards), reflecting the quality of the faunal communities. Using data from the GQA site named Testwood, the Lower Test has consistently been given a score of „A‟ since monitoring started at this site in 1995. The sites that are immediately upstream and downstream of the abstraction also score equally well and have always achieved an „A‟ grade. A GQA score of „A‟ implies that the invertebrate community does not appear to be impacted by poor water quality.

Water Framework Directive ecological status

Currently, ecological status is determined by an updated classification method using RICT (River Invertebrate Classification Tool (derived from RIVPACS)) under the direction of the EU Water Framework Directive (WFD) (2000/60/EC). The Lower River Test (Waterbody ID: GB107042016840) runs from the confluence with Tadburn Lake, south of Romsey, to the confluence with River Blackwater. The current ecological status of the macroinvertebrate community in this stretch is considered to be High (with high confidence) under the conditions set by the WFD. A „High‟ status indicates that the water body is supporting a diverse and abundant invertebrate community.

Average Score per Taxon

It is possible to give a simple indication of biological quality of the area immediately around the abstraction intake, by using Average Score per Taxon (ASPT). This is a biotic score that is widely recognised as the most robust measure of water quality (Mason, 1991). ASPT effectively represents the average pollution sensitivity of the macro-invertebrate community. Observed (O) ASPT values can be divided by Expected (E) ASPT scores generated by RIVPACS to give OE ASPT. The closer the OE ASPT value is to 1, the more unstressed and undamaged the macro-invertebrate community is. If the OE ASPT value falls below 1, the more ecological stress is indicated. Charts within the report by the Environment Agency (2010a) show that the OE ASPT from all of the samples collected from the three sites around the abstraction intake are of very good biological quality. The OE ASPT always remains above 1 which means that the Lower River Test is achieving a greater ecological quality

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2.4.1.2. Available data from downstream of the Testwood intake In 2002, the EA began collecting aquatic macroinvertebrate samples from upstream and downstream of the intake to specifically gather data with which to assess the effects of the abstraction. In its review of the data in 2008, the Environment Agency concluded that a change was required to the sampling approach, such that the 3-minute kick method was still employed but within a fixed area, rather than across the entire cross-section of the river channel at the sampling point. This approach was followed for samples taken from 2010 onwards (no data were collected in 2009). The reasons for the change in procedure are explained in the Environment Agency‟s report (2010a) and relate to the depth of the water in the river. The NEP investigation has taken the historic dataset, and continued the sampling effort where possible given access permission, thus following the Environment Agency‟s (2011c) recommendations. Section 7.3 details a statistical assessment of the full historic dataset that was undertaken to see if it could be wholly used in the NEP. Following the statistical assessment, the data are used to perform a hydroecological assessment to assess the effect of the Testwood Abstraction.

2.5. Protected Species

2.5.1. Introduction

This section presents information relating to protected species that have been identified by the Environment Agency (2011c) that are not considered elsewhere in Section 2. The species are listed in Table 2.5.1 which also presents information on their level of ecological designation and preferred hydroecological conditions.

Table 2.5.1 Protected Species Last survey Species Legislation Notes year Require sensitive bankside vegetation Otter Habitats Directive, 2006 management and water levels that support Lutra lutra Biodiversity Action Plan healthy fish populations Vulnerable to varying water levels that may Water vole Biodiversity Action Plan cause the flooding of burrows or allow Arvicola terrestris 2000 predators to attack Needs high water cover; drastic changes in White-clawed crayfish Habitats Directive, water level may detrimentally affect 1999 Austropotamobius pallipes Biodiversity Action Plan populations. Not listed in the River Test SSSI citation but believed to be present. Southern damselfly Habitats Directive, Need high water levels for maintenance of 2006 Coenagrion mercuriale Biodiversity Action Plan preferred habitat Source: Amended from Table 11 in Environment Agency (2011c) Figure 2.5.1 presents sightings of these species based on the records held on the Hampshire and Isle of Wight Wildlife Trust‟s (HIoWWT) database (from the past 15 years). The Environment Agency (2011c, p97) state that “there are very few documented records of amphibians and reptiles within the project area although species within these categories are obviously present.” The paucity of data may be due to the lack

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2.5.2. Otter

Otters (Lutra lutra) are very mobile, with a large territory, the extent of which is partially dependent upon prey availability and cover. The species itself is unlikely to be directly affected by abstraction although there could be indirect effects should its prey be affected; suffice that a watercourse does not dry up entirely, it is likely there will be little impact on otters (Environment Agency, 2011c). The Hampshire and Isle of Wight Wildlife Trust (pers. comm.) last undertook formal surveys in 2006 (the results are shown in Figure 2.5.1); no subsequent surveys have taken place due to access restrictions however it is considered highly likely that otters are present on the main channel and some / all associated side channels of the River Test and the River Backwater within the study area of the Lower Test NEP Investigation. There have been a number of recorded otter sitings within the Lower Test Nature Reserve (see Figure 2.5.1), which is thought to be a „hot-spot‟ area of high otter activity. However despite evidence and sightings of otters in the Lower Test Marshes, there has not been a systematic survey to identify possible breeding status and distribution of activity in recent years.

2.5.3. Water vole

Water voles (Arvicola terrestris) have become increasingly rare in many parts of southern Britain, although there is still evidence of this species in the Test and Itchen catchments. The species is dependent upon in- stream macrophytes and bankside/riparian wetland plants for food and cover, and requires access to banks, below and above a stable water level in which to burrow. The small fluctuation in water levels experienced on the Rivers Test and Itchen may be an underlying reason for these rivers acting as a water vole stronghold (Environment Agency, 2011c). The species is particularly vulnerable to dramatic water level fluctuations, such as flood events, that may result in burrows being flooded out. While the species may survive by swimming away, they may be displaced to sub-optimal habitat and become vulnerable to predators. Water voles also require banks into which they can burrow. The HIoWWT (pers. comm.) last undertook formal surveys in 2000 (Figure 2.5.1 shows the results of those surveys). As for otters no subsequent surveys have taken place due to access restrictions however it is believed that water voles are present in the Lower Test valley, both on the main river and in the network of channels that criss-cross the floodplain. The Trust considers that water voles are not present on the Blackwater, due to its flashy / spatey nature and the fact that mink, a predator, are known to be present in this catchment. The Environment Agency (2011c, p41) state that, “changes to flow management, drainage practices and water levels are key to maintaining this species. Abstraction is unlikely to be a key factor, unless the impact, even locally, is significant. Any impacts are likely to be mitigated by management of flow into and within floodplain ditches, reversing historic land drainage practices and appropriate water level management and sympathetic land use management.”

2.5.4. White clawed crayfish

White-clawed Crayfish (Austropotamobius pallipes) is the only native species of crayfish, and has also become rare throughout England and Wales. Crayfish occupy a wide range of aquatic habitats but prefer alkaline water with limited sediment, free of pollution and plenty of shelter in the form of rock, aquatic plants and tree roots.

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2.5.5. Southern Damselfly

Surveys for the River Test WLMP (in 2006) and by the Wildlife Trust (in 2009) only found a few adult Southern Damselflies in the Lower River Test catchment, in a small ditch. Neither adults nor larvae have been found in or near the River Test around the abstraction intake. The preferred habitat of the Southern Damselfly comprises flowing ditch type water channels with emergent vegetation and poaching. The species would not be expected to inhabit the main River Test channel as the flow is too large. As stated in Table 1.2.1, the Environment Agency has stated that Southern Damselfly would not be expected to inhabit the area downstream of the public water supply abstraction intake and therefore no monitoring or assessment for this species is required for the NEP.

2.6. Floodplain macroinvertebrates

Neither the River Test SSSI nor the Lower Test Valley SSSI refers specifically to the floodplain invertebrate species in lower reaches of the river, however due to the mosaic of different habitats in the Lower Test Valley SSSI, from freshwater to saltmarsh, reflecting the different water chemistry is it likely that the invertebrate community is diverse. Figure 2.6.1 shows the micro-habitats favoured by wet grassland micro- habitats, and all of these are found in the study area: open water margins, reedbeds, brackish marshes, aquatic water channels of varying sizes and salinity, and saltmarsh. Benstead et al. (1999) provide an account of the hydroecological requirements of invertebrates associated with floodplain wet grassland. Wet grassland supports a wide range of invertebrates including ground beetles, snails and the adult forms of many species which have aquatic larvae, for example dragonflies and caddis flies. Maintenance of floodplain invertebrate biodiversity is not only important for its own intrinsic value, but also as the community provides an invaluable food source for wetland birds, the abundance of which is often correlated with the availability of their aquatic invertebrate prey. Invertebrate diversity and the number of rare species tend to be associated with environmental heterogeneity in the wet grassland landscape which is increased by the presence of biotopes such as damp hollows and temporary pools, channels and old trees. Invertebrates are also an important food source for breeding wildfowl and waders. Management of wet grassland to create a mosaic of microtopography and range of variation in vegetation structure support highest biodiversity within these habitats. For the Lower Test, it is considered important to maintain fresh to brackish water transitions and transitions from aquatic habitats to terrestrial habitats, and a range of open water areas ranging from temporary to permanent water bodies, small and large. Although it is difficult to be specific about the requirements of wet grassland invertebrates because of their huge variety, certain generalisations can be made. Vegetation structure and composition are key factors, as

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2.7. Wetland Habitat/Flora

The vegetation of the Lower Test Valley SSSI has been surveyed by Neil Sanderson for the Hampshire Wildlife Trust. Areas further north around the area known as Manor Farm have been surveyed by the Environment Agency. Figure 2.7.1 shows the results of the most recent survey in 2008, which mapped the distribution of different habitat types within the Lower Test Valley SSSI boundary. Habitats contained within the Lower Test Valley SSSI include neutral grassland, saltmarsh, ditches, swamps, reed beds and areas of wet woodland (see Section 2.1). The distribution of different habitat types reflects the extent and magnitude of the tidal influence and the distribution of different soil types across the Lower Test Valley. Five main vegetation zones can be broadly identified from south to north as follows: 1. SM16c saltmarsh communities in the southernmost part of the Lower Test Valley SSSI; 2. Swamp habitats, specifically S4 Phragmites australis reedbed with some S6 Carex riparia, are found to the north; 3. Inundation grassland, mainly MG10 flush pasture and MG11 short flood pasture; 4. MG8 short fen meadow and M22 tall fen (wet) meadow is found in the northernmost part of the Lower Test Valley SSSI. These fen communities grade to S5–S7 swamp along the historic ditch/meadow features; and 5. North of the SSSI boundary, in the area known as Manor Farm, Environment Agency surveys have identified MG6 and MG8 (dry) fen meadow with M22 in the lower lying areas that are more frequently flooded. More subtle variations in habitat distribution occur across this broad zonation. For example, inundation grassland extends far down the banks of the Great Test, and saltmarsh areas can be found on the west bank of the Middle Test and west bank of the Little Test in the swamp zone. Many of the ditches and watercourses are lined with W6 scrub and woodland. Summary descriptions of each of the communities described above are provided in Table 2.7.1. A full list of the vegetation communities recorded in the Sanderson 2008 survey is provided in Table 2.7.2. The different vegetation zones reflect the changing influence of coastal and fluvial processes. The transition between swamp and inundation grassland in particular also demarcates the boundary between the Wallasea and Wilingham soil types; where the soil consists of clay-over-gravel, saltmarsh is found in the area of direct tidal influence and reed grading to swamp habitat in brackish areas. Where the clays give way to the silts and peats, grassland habitats are dominant.

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Table 2.7.1 Description of the five main vegetation zones in the Lower Test SSSI

Explanatory Designated description of Habitat/ Species type Character and/or water level requirements features the feature for clarification Zone 1 Saltmarsh SM16c S4 Phragmites Zone 2 Swamp Reed bed australis MG11 Festuca Inundation grasslands frequently flooded by rubra – Agrostis Lowland neutral stolonifera – fresh or brackish water but also prone to Inundation grassland Zone 3 Potentilla anserina drying out grassland MG10 Holcus Ordinary damp meadow rush pasture found lanatus – Juncus Rush pasture in areas with permanently high water table. effusus Not normally flooded Rare habitat. Deliberately flooded in past for MG8 Meadow long period in winter and spring. Constantly Wet fen damp soils Zone 4 Mire grassland derived from rich fens on meadow M22 Juncus subnodulosus – Rich fen moist sites that have been ditches and mown, meadow often flooded in winter. Soils moist to damp Cirsium palustre for most of the year. Dry fen Very common in pastures in lowland Britain. Zone 5 meadow MG6 Hay Pasture Soil moist but free draining. No flooding, or only in very exceptional years Found on wet, nutrient-rich soils e.g. shallow Alder – nettle Woodland W6 banks along brook meanders that receive a woodland lot of sediment-rich winter flood water Reed Regularly very prolonged winter flooding, S5 Glyceria maxima sweetgrass usually in waterlogged sites with water at soil swamp surface for most of the summer Ditches Wet hollows within flood meadows. Regular Great Pond prolonged winter flooding. Continuous S6 Carex riparia Swamp Sedge swamp waterlogged site (community also occurs in up to 0.2 m of water). Wet hollows within flood meadows. Regular Lesser Pond prolonged winter flooding. Continuous S7 Sedge swamp waterlogged site (community also occurs in up to 0.2 m of water). Source: adapted from Environment Agency (2011c)

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Table 2.7.2 The list of the vegetation communities recorded in the Sanderson 2008 survey

NVC habitats Saltmarsh  Spartina anglica Saltmarsh (SM6)  Juncus gerardii Saltmarsh Festuca rubra –  Salicornia Saltmarsh (SM8) Glaux maritima sub-community (SM16c)  Puccinellia maritima Saltmarsh (SM13)  Juncus gerardii Saltmarsh tall Festuca rubra  Puccinellia maritima Saltmarsh Puccinellia sub-community, SM16d maritima dominant sub-community (SM13a)  Juncus gerardii Saltmarsh Leontodon  Puccinellia maritima Saltmarsh Glaux maritima autumnalis sub-community Trifolium repens sub-community (SM13b) variant (SM16ei)  Atriplex portulacoides Saltmarsh, Atriplex  Phragmites australis Swamp Atriplex sub- portulacoides dominant sub-community (SM14a) community Agrostis stolonifera variant  Eleocharis uniglumis Saltmarsh (SM20) (SM4ciii)  Juncus gerardii Saltmarsh (SM16)  Puccinellia distans Saltmarsh (SM23)  Juncus gerardii Saltmarsh Puccinellia maritima  Elytrigia atherica Saltmarsh SM24) sub-community (SM16a)  Armeria – Cerastium diffusum Maritime  Juncus gerardii Saltmarsh Juncus gerardii sub- Therophyte Community (MC5) community (SM16b)  Buttonweed Community (BW)*  Atriplex prostrata-Beta vulgaris Maritime Community (MC6) Aquatic communities  Lemna minor Community (A2)  Elodea spp Community (A15)  Nuphar lutea Community (A8)  Callitriche spp Community (A16)  Potamogeton pectinatus Community (A12)  Ranunculus penicillatus pseudofluitans Community (A17) Inundation grassland  Holcus lanatus – Deschampsia cespitosa  Festuca arundinacea Grassland (MG12) Grassland Poa trivialis sub-community (MG9a)  Agrostis stolonifera – Alopecurus geniculatus  Juncus inflexus sub-community (MG10b) Grassland (MG13)  Iris sub-community (MG10c)  Festuca rubra – Agrostis stolonifera –Potentilla anserina Grassland Lolium perenne sub- community (MG11a) Fen meadow  Cynosurus cristatus – Caltha palustre Grassland  Juncus subnodulosus – Cirsium palustre Fen (MG8) Meadow (M22) Swamp  Phragmites australis Swamp (S4)  Glycerion – Sparganion Water Margin  Glyceria maxima Swamp (S5) Vegetation (S23)  Glyceria maxima Swamp Glyceria maxima (S5a)  Phragmites australis – Urtica Fen (S26)  Carex riparia (S6)  Phalaris arundinacea Tall Herb Fen (S28)  Typha latifolia Swamp (S12)  Agrostis stolonifera sub-community of Phalaris  Sparganium erectum Swamp (S14) arundinacea Tall Herb Fen (S28)*  Carex acutiformis Swamp (S7)  Agrostis – Alopecurus Pasture (MG13)  Eleocharis palustris Swamp (S19)  Epilobium hirsutum Community (OV26)  Schoenoplectus tabernaemontani Swamp (S20)  Water Margin Vegetation / Rorippa palustris –  Bolboschoenus maritimus Swamp (S21) Gnaphalium uliginosum Community*  Glyceria fluitans Swamp (S22)  Carex riparia / Glyceria maxima Swamp* Dry and improved grasslands  Arrhenatherum elatius Grassland (MG1)  Festuca ovina-Agrostis capillaris-Rumex  Cynosurus – Centaurea Grassland (MG5) acetosella Grassland Hypochaeris radicata  Lolium-Cynosurus Grassland (MG6) sub-community (U1f)  Lolium Grassland (MG7)  Lolium – Dactylis Community (OV23)  Poa annua – Plantago major Community (OV21)  Urtica dioica – Galium aparine Community (OV24) Scrub and woodland  Alnus – Urtica Woodland (W6)  Ulex – Rubus Scrub (W23)  Quercus – Pteridium – Rubus Woodland typical  Urtica – Galium aparine Community (OV24) sub-community (W10a)  Rubus – Holcus Under Scrub (W24)  Crataegus – Hedera Scrub (W21) * Not described in the NVC Source: adapted from Environment Agency (2011c)

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2.8. Breeding waders and passerines

The River Test and floodplain provides a valuable habitat for wetland birds. The SSSI citation cites a diverse range of characteristic riverine species which breed in the site including kingfisher Alcedo atthis, grey wagtail Motacilla cinerea and little grebe Tachybaptus ruficollis. In the dense vegetation along its margins coot, Fulica atra, and moorhen, Gallinula chloropus, are frequent and tufted duck, Aythya fuligula, pochard A. ferina and mute swan Cygnus olor also nest. Sedge warbler, Acrocephalus schoenobaenus, and reed warbler, A. Scirpaceus, can be numerous in the tall vegetation with scattered scrub along the water courses. The Environment Agency‟s Baseline Data Report (Environment Agency, 2011c) details the 2002 Hampshire Ornithological Society (HOS) survey of fen and reed breeding birds, and breeding waders. The survey provided a comprehensive bird survey coverage of the valley, and included three zones that were close to the NEP study reach. The counts undertaken in these zones found very few pairs of breeding waders which was attributed to a lack of suitable habitat. The River Test WLMP (Environment Agency, 2006b) reporting on the same dataset, cites the Hampshire Wildlife Trust (pers. comm.) as believing that the numbers of redshank have declined further since the 2002 survey. Consultation during this NEP investigation with the site manager of the Lower Test Valley reserve, who undertakes regular bird counts, reveal that the historic areas favoured by breeding waders are in and around the Little Test. The fields are shown in Figure 2.8.1, which also shows the results of the Trust‟s 2011 bird survey with regard to reed and sedge warbler and the 2008 NVC vegetation survey. However, there are now no pairs of breeding waders on site in the Lower Test Valley; the last sighting of breeding lapwing and redshank was in 2002 and 2004 respectively (HIoWWT, pers. comm.). The decline is attributed to an increase in saline or brackish conditions in the marsh from increased tidal inundation during the spring in recent years, possibly as a result of sea level rise. In addition, changes in habitat type from scrub invasion reflecting a move away from the cycles of floodplain flooding and subsequent drying to one where the floodplain is becoming dry. The River Test WLMP (Environment Agency, 2006) provides the following reasons for the loss of this cycle of flooding and drying of the floodplain:  A progressive simplification of the drainage system within the floodplain with many former water courses used as part of the water meadow system, becoming dry and abandoned;  Associated with a decline in many drainage channels has been a greater concentration of flow within the remaining main river channels. Bank repair and improvements to these channels has been undertaken to keep water within them and prevent flooding of the adjacent floodplain;  Control structures that were built to manage water levels in the floodplain have been abandoned and removed so that it is difficult raise water levels and create the desired floodplain conditions;  Associated change in habitat type and structure away from that preferred by breeding waders, such as a mosaic of different grassland swards to reed bed, fen or wet woodland; and  The total volume of water available to the system may have been reduced through abstraction. This makes it more difficult to effectively „share‟ the resources between the main channels and the floodplain.

Areas of historic breeding wader habitat are also linked to historic meadow systems via sluices from Nursling/Conagar and the Test Back Carrier (Section 3.4). It is likely that the progressive dereliction of these historic water supply systems coupled with the reduction of flow into the meadows as water management has focussed on maintaining water in-channel for fisheries objectives has at least contributed to the reduction on breeding wader potential in the historic wader fields shown on Figure 2.8.1.

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The Lower Test Marshes covers an environmental transition from freshwater to saltwater: the range of intertidal habitats present comprise reedbed, brackish marsh, saltmarsh and estuarine mud. The Environment Agency (2011c) states that inclusion of the Lower Test Marshes in the Solent Maritime SAC was largely to accommodate this transitional habitat. The Environment Agency (2011c, p76–77) states that “Abstraction can directly affect these habitats and associated dependant species, if it changes (lowers) the ground water regime, reduces soil moisture or significantly depletes the availability of surface water to the floodplain and watercourses within the floodplain. It is likely that impacts on water levels can be mitigated by management of flow into and within floodplain ditches, reversing historic land drainage practices and appropriate water level management and sympathetic land use management. Abstraction is only likely to be a key factor if its effects on water levels is significant, to the extent that there is insufficient water to manage, in terms of flows into ditches and water levels with ditches, and surface water flows onto the floodplain for periods in the winter months.... The other key value of freshwater input is to the transitions from fresh to saltmarsh vegetation. The mechanisms by which freshwater influences the distribution of brackish marshes on the floodplain is not fully understood, however, it is apparent from the repeat vegetation surveys that there have been significant changes over the last decade. These may be due to changes in the flow of freshwater down the Middle River but sea level rise is also likely to have had an influence. With predicted further changes in sea level it is imperative that the mechanisms that operate in mixing fresh and salt water in the Lower Test Valley are more clearly understood so that management regimes can be put in place that ensures the current transitions are maintained and are able to respond to changing sea levels.” As the water abstracted at Nursling Fish Farm historically flowed across the Lower Test Valley, the reduction in the volume of this abstraction (see Section 1.5.1, Section 3.7.4 and Figure 3.7.7) and associated reduction of freshwater input to the Lower Test Valley SSSI may be a contributory factor influencing the expansion of saline and brackish communities in the lower part of the SSSI since 2003 (see Environment Agency, 2011c), although this cannot be fully confirmed. A similar reduction in freshwater flows in the Middle Test may have occurred since Structure 1417 was shut. Structure 1417 controls the passage of water from the Great Test into the Middle Test channel. This structure has been kept shut over the last few years, although two breaches have developed in the south bank of the structure that still convey water from the Great Test into the Middle Test (see Section 3.7.2 and associated figures).

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3.1. Climate

A number of rain gauges are located in the Test catchment, with one located at Testwood. The mean annual rainfall total for the Testwood gauge is approximately 662 mm. No measurements of evaporation are made by the Environment Agency in the Test Catchment. There is an evaporation pan and climate station in the Itchen catchment. As this catchment is adjacent to the Test it can be used as a surrogate; the data can give an indication of the likely evaporation from the Test catchment, which the Environment Agency (undated) state to be 350 mm (long term average).

3.2. Soils and geology

Soil types and characteristics are summarised in Table 3.2.1 and Figure 3.2.1. The dominant soil type to the south of the Test Valley are clays of the Wallasea association (Soil Survey of England and Wales, 1983) (Figure 3.2.1), described as pelo-alluvial gley soils with significant shrink-swell potential. These soils are typical of coastal marshland in southern England for example on the Romney and North Kent Marshes (Kent), and the Pevensey Levels (East Sussex), Pulborough and Amberley Wildbrooks (West Sussex) and the Brading Marshes on the Isle of Wight. Wallasea association soils are characterised by a low hydraulic conductivity (a measure of the speed with − − which water moves through the soil). Estimates ranging from 2.77×10 5 to 5.8×10 2 metres per day have been obtained from field investigations of equivalent soils on the North Kent Marshes and Pevensey Levels by Gavin (2001) and Armstrong (1994) respectively. Even at the highest values of hydraulic conductivity recorded, this is equivalent to a particle of water taking 172 days to travel a distance of only 10 m, highlighting the impermeable nature of these soils. The thickness of the clay is variable, ranging from 3 m in the south close to Redbridge to less than one metre in and around Ruddy Mead based on British Geological Survey (BGS) borehole logs (Figure 3.2.2). The stratigraphy underlying the clay reflects the changing depositional character of the Solent throughout the Quaternary, with lenses of peat and layers of sands that vary in grade from clayey and silty material to coarser sands and gravels (Figure 3.2.2) at different locations in the Lower Test Valley. Soils in the northern half of the Lower Test Valley are of the Willingham series (Figure 3.2.1) described as „moderately permeable, stoneless, extremely calcareous, loamy or clayey soils formed in lake marl, tufa or peat‟ (Hey et al. 1960). The transition between Wallasea and Willingham soil series corresponds broadly with the transition from swamp and saltmarsh communities to neutral grassland. This boundary also appears to delimit the historic tidal limit; the calcareous nature of Willingham soils identifies the predominant influence of upstream (fluvial) rather than downstream (tidal) processes wherever this soil type occurs. The extent of Willingham soils in England is limited to 43 km2, occurring mainly on the beds of former pools in the fens of Cambridgeshire with some small areas in the Idle Valley in Nottinghamshire. Willingham series soils are described by soil survey literature as silty soils over peat. However, BGS borehole logs in and around Nursling describe these soils predominantly as „soft sandy silty clays underlain by soft dark brown peat‟. The sandy silty clays are 0.2–0.7 m deep, and the peat is 0.5–1.0 m deep. There is typically a further layer of sandy silty clay beneath the peat approximately 0.5 m deep in some cases mixed with peaty or gravelly deposits. Gravel deposits 3–4 m thick underlie the whole northern part of the Lower Test Valley and soils pass to gravels some 1.5–2.0 m below the ground. Soil cores taken for the NEP investigation in the

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Table 3.2.1 Soil types and characteristics of the Test Valley

Soil series Description Detail

Deep silty over Extremely calcareous silty and clayey soils. in places humose. and often Willingham peat over peat. Some patches of deep peat Deep stoneless well drained silty soils and similar soils affected by Hamble 2 Deep silty groundwater, over gravel locally. Seasonally wet Deep stoneless non-calcareous and calcareous clayey soils. Soils locally Wallasea 1 deep clay have humose or peaty surface horizons Seasonally wet Coarse and fine loamy permeable soils mainly over gravel variably Hurst deep loam affected by groundwater. Source: Hodge et al.(1984)

3.3. Topography

Figure 3.3.1 shows the topography of the Lower Test derived from LiDAR5 data. It can be seen that there is a general southerly decline in ground levels across the Lower Test Valley, from approximately >3 m OD in the north west of the view shown in Figure 3.3.1 to approximately −8 m OD in tidal creeks in the south west. To the south, the surface micro-topography is characterised by a dense network of shallow dendritic channels that are relic and active saltmarsh features. Further north, the fields show an extensive network of undisturbed ridge and furrow of significant archaeological and historical interest (as can be seen on Figure 3.3.1 and also Figure 3.7.10). These meadows are likely to date to the 1640s and 1650s when there are numerous references to water meadows being constructed in the local area (Bettey, 1999). The ridge and furrow system provides a preferential pathway for the movement of water, linking different parts of each field. Historically, these would have been „stopped‟ at the ends to deliver flooding during early spring. However, in their current arrangement, the surface ridges will act to drain water away from field surfaces and into ditches. The ridge and furrow system provides an invaluable means of wetting up wet grassland areas within the Lower Test Valley, especially in the northern area of the Hampshire and Wildlife Trust Nature reserve and the area known as Manor Farm. Adequately designed water level management structures could serve to deliver extensive areas of flooding with the extensive margins required by wading birds characteristic of this habitat type, as discussed in the River Test WLMP (Environment Agency, 2006). This action is outside of the NEP investigation, however it could be delivered by the Environment Agency through the River Test Water Level Management Plan (2006).

5 LiDAR (Light Detection And Ranging) is an optical remote sensing technology that can measure the distance to, or other properties of a target (such as elevation) by illuminating the target with light, often using pulses from a laser. It is frequently used as a fast way of surveying as topographic maps can readily be generated from LIDAR.

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The Lower Test is characterised by several significant flow splits. A simplified representation of the flow distribution of the Lower Test showing flow splits is presented in Figure 1.1.3 and Figure 3.4.1 shows the magnitude of the main splits which are described below. Each split takes water away from the main channel of the River Test, thus depleting the water within it. Some of the flow splits are licensed abstractions; others are not. In addition to the flow splits listed below, Figure 3.4.1 also shows the contribution of the River Backwater, a tributary that join the main channel of the Lower River Test downstream of the location of the Testwood PWS abstraction and Testwood GS.  Broadlands Fish Farm Carrier – split from the main Test upstream of Broadlands GS which diverts water to the River Blackwater downstream of Ower GS. The carrier was initially created to feed the Broadlands water meadow system, but more recently part of the Broadlands Fishery used for angling. Spot flow data from 1998–2008 indicate average flows of 0.83 m3/s (72 Ml/d) and a Q95 of 0.53 m3/s (46 Ml/d). The scheme is unlicensed.  Test Back Carrier – drains Longbridge Lake further upstream in the catchment and returns flows to the Little Test. The carrier is connected to a dry channel that exits the main Test downstream of Broadlands GS. Currently this carrier is thought to receive very little flow from the Test except from floodwaters in the winter. Gauged flow data from 1986–2002 indicate highly variable flows with an average flow of 0.15 m3/s (13 Ml/d). Historically there have been higher flows in the carrier but they appear to have diminished as a result of silt build-up.  Great Test/Little Test Split – split of the main Test into the Great Test (western channel) and the Little Test (eastern channel). The diversion is controlled by a set of hatches. An agreement in 1831 (Coleridge Award) stated that the hatches should be operated such that at least two-thirds of the flow in the main river passed down the Great Test. No operating protocols are however in place to maintain flows as per the Coleridge Award.  Nursling Fish Farm Carrier – main outlet for the fish farm at Nursling on the Great Test via a siphoned piped discharge downstream Testwood PS about 1 km from the fish farm inlet. The fish farm has a maximum daily licence of 0.53 m3/s (45.5 Ml/d) (since 1990), but with no requirement to measure discharges. Returns from 2001–2008 suggest an average flow of 0.15 m3/s (13 Ml/d). Gauged flow data from 1983 to 1991 indicate flows in the range of 0.58 to 1.16 m3/s (50 to 100 Ml/d).

3.5. Hydrology of the Lower River Test

Chalk rivers are characterised by a baseflow dominant flow regime: the slow release of water from the aquifer attenuates rainfall events, providing a steady flow regime with a characteristic cycle. Some rainfall events can induce a more rapid response, termed a „freshet‟ if the aquifer and land are saturated, or there are areas of impermeable deposits over the chalk. Chalk rivers start to show a rise in water levels and river flow from mid to late winter following the onset of winter rains, until March or April. From this point flows start to decline over summer and autumn, reaching minimum flows in October until the onset of the rains begins again. There are numerous locations where flow in the River Test is measured by the Environment Agency, as shown on Figure 3.5.1. Different techniques are used at different gauges and data are available for different time periods. Full details of the Environment Agency‟s flow measurements are given in the Phase 1 Baseline Data report (Environment Agency, 2011c). As discussed in Section 3.5.2, the flow in the River Test and tributaries is gauged at a number of locations, and each gauge has a different length of data available. The Testwood Gauging Station is located within the study reach and therefore is the main source of flow data for the Lower Test NEP Investigation. Data has

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3.5.1. Hydrology of the NEP study period

Figure 3.5.2 shows the natural variability of the annual hydrograph of the River Test as measured by Testwood GS from 1988–2011, illustrating the pattern of rising flow over late October to November with maximum flows experienced over February to April. The timing of the rise and maximum discharge varies annually as it is dependent upon the onset of rainfall. Flows decline over summer until the lowest flows are experienced from late August to October. The years 2006 and 2007 are highlighted on the figure (i.e. the lines on the figure are thicker than other lines) to emphasise these years. This is because, within the NEP Investigation with its study period of 1996– 2011, the years 2006 and 2007 are used as representative dry and wet years respectively. Figure 3.5.2 shows that at Testwood, 2006 was a very low flow year, together with other years such as 1989 and 1996 which also exhibit very low flows (but for which salmon count data is not available). Similarly, 2007 is a good year to use for high summer flows, as this year shows the highest flows from mid July to the end of August. In order to assess the hydrological conditions of the study period in the context of a longer term flow record, data from Broadlands Gauging Station has been used, as this data is available from 1957. The Broadlands gauge is located approximately 4 km upstream of the Testwood Gauge, see Figure 3.5.1. Figure 3.5.3 shows the natural variability of the annual hydrograph of the River Test as measured by Broadlands GS from 1958– 2011. Flows recorded at Broadlands GS range between approximately 4 to 37 cumecs (327 to 3176 Ml/d). As for Figure 3.5.2, the lines on the chart for the years 2006, 2007 plus 1976 on Figure 3.5.3 are thicker than others to help emphasise these years. The figure shows that for Broadlands, 1976 was overall the lowest flow year on record, but that other years also exhibited comparative flows, including 2006 which has lower flows than 1976 from late August to November. There is no clear overall high flow year, with high flows recorded in different years. However, the representative high flow year chosen for the NEP study, 2007, is seen to be amongst the highest flows recorded for the summer months at Broadlands. In order to compare the data for the NEP study period, Figure 3.5.4 shows a summary of the data from Broadlands (the minimum and maximum flows experienced, plus the annual time series of 1976, 2006 and 2007) together with flow data from the Testwood Gauge (the annual time series for 2006 and 2007). This figure helps to understand the range of flows experienced in the study reach during the study period, relative to the long-term record of Broadlands GS. Overall it can be seen that flows recorded at Testwood GS are lower than those recorded at Broadlands GS but follow the same trend. It can be seen that the NEP „low flow‟ year of 2006 is indeed representative of very low flow conditions: the flows at Testwood GS are lower than the minimum flow recorded at Broadlands GS; even lower than 1976. Likewise the NEP „high flow‟ year of 2007 is also representative of high summer flow, with flows reducing in autumn. Further to this, Figure 3.5.5 presents all the years within the NEP study period as black lines, against green lines of the remaining historical record at Broadlands GS (NB 1976 is shown by a red line). The range of flows experienced within the NEP study period spans high and low flows, and can be considered representative of the range of hydrological conditions recorded historically at Broadlands GS.

3.5.1.1. Frequency of extreme low flows In order to set the context for the NEP investigation and assess periods of extremely low flows, attempts have been made to look further back in time before 1957. Due to the lack of hydrometric data from the River Test before 1957, output from the Test and Itchen Groundwater Model has been used, as the simulated flow time series extends from 1920. A high level assessment has been undertaken in order to understand the frequency and duration of extreme low flow events, and also the potential impacts of abstracting at the full licensed quantity during such periods. A summary is presented below, with Appendix 3.5.1 providing more detail. The long-term flow series was created using the abstraction and flow management conditions operating in the river in early September 2006. It is relevant to note that at this time, the split in flow between the Great and Little Test was not in accordance of the Coleridge Award (see Section 3.7.5) of 66% and 33%

6 While 1989 and 1990 also exhibit very low flows, fish count data is not available for these years, whereas it is for 2006. See Section 6.

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3.5.2. Derivation of approved flows

Concerns were raised by the Steering Group about the accuracy of some of the gauges used in the NEP investigation such that a decision was made that a study was made into the optimal approach to derive river flows at certain points along the River, with the conclusions and resulting flows approved by the Steering Group. The outcome of this study is presented in Appendix 3.5.2, and summarises the key characteristics of the different gauges on the Lower Test and the selection of gauges from which the approved flow time series is generated. The derivation of flows outlined in Appendix 3.5.2 builds upon previous studies on the hydrology of the area notably reports by the Environment Agency (2009a, 2011). These reports provide a thorough understanding of the hydrometric network and data for the Lower River Test and the reader is referred to them for a full understanding of the hydrometric network of the River Test and routine monitoring undertaken by the Environment Agency.

3.5.2.1. Summary of freshwater flows As stated in Section 3.5.1. the flow regime of the River Test is that of a classic chalk stream, in that it is dominated by the baseflow input from the main chalk aquifer that underlies much (approximately 90%) of the catchment. In keeping with a chalk baseflow system, peak flows occur as autumn and winter rainfall recharges the aquifer which in turn discharges to the river. In late spring, as recharge reduces or ceases altogether, the discharge from the aquifer to the river reduces and flows gradually recede through the summer and early autumn. Although significant rainfall events in the summer and early autumn can cause flows to rise, the lowest flows each year are essentially determined by the recharge of the aquifer in the preceding winter and early spring. Figures 3.5.6 a to e show the flows for the following locations along Lower River Test derived for the NEP investigation:  A: Main Test downstream of Longbridge GS and upstream of the Little and Great Test flow split;  B: Great Test downstream of the Little and Great Test flow split and upstream of the Nursling Fish Farm offtake;  C: Great Test downstream of the Nursling Fish Farm Offtake and upstream of the Testwood Abstraction;  D: Great Test downstream of the Testwood Abstraction and upstream of the Blackwater confluence;  E: Great Test just downstream of the Blackwater confluence ;  F: Great Test at the MRF location;  G: Great Test downstream of the MRF and upstream of Testwood Pool; and  H: The Little Test downstream of the Little and Great Test flow split.

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3.6. Tidal influence

The upper boundary of this NEP study area is located upstream of the tidal section of the River Test: the Testwood abstraction is sited at the natural hydraulic limit of the tide. The location of the normal tidal limit is marked on Ordnance Survey maps, on various figures of this NEP report, and the influence of the tidal regime can be seen in the vegetation present on the Lower Test valley (see Section 2.7). A site visit on 29th November 2011 showed that at certain times the entire valley becomes tidally inundated. This site visit coincided with a high spring tide and the passage of a deep low pressure area that triggered a number of flood risk alarms in the Solent (Environment Agency, pers. comm.). This high spring tide resulted in the extensive inundation of the Lower Test Valley SSSI and within the lower reaches of the River Test more generally (see Section 5.1). The tidal regime can be seen in the data from the tidal gauge at Eling Mill which is located just downstream of Redbridge, in Southampton Water. Tidal water level variations affect the hydrology of the River Test through impounding freshwater flows during high spring tide periods leading to tidally induced changes in water levels at Testwood Gauging Station (see Section 5.1). In order to explore more fully the effect of the tidal influence upon the freshwater hydrological regime for the NEP, data from a number of water level gauges have been examined. Section 5.1 presents the results and analysis of this part of the NEP investigation.

3.7. Structures and water level management

The Lower Test is a highly managed river system. Historical modifications to the lower reaches of the river over the centuries have created a river with many channels. The modifications have been primarily driven by alterations (realignment and deepening) to channels and carriers for agriculture and land drainage. A series of sluices are associated with Nursling and Testwood Mill on the Great Test. There is a network of historic structures used to distribute water from the main river systems out to the meadows that lie between the Great Test and the Little Test but this is largely defunct. Leats were constructed to channel water from the river toward mills that were used for various industries including tanning and flour milling. The construction of sluice systems and creation of channels for water meadows, water mills and navigation over the centuries has considerably modified the river and water level management. Drainage activities in the 1940s involved the dredging of the river channel to allow arable production on the floodplain. The water level control structures in the Lower Test not only influence the water level and direction of flow but also water velocity and the movement and deposition of sediment within the channel. Sediment deposition upon the river bed may affect the quality of spawning habitats for salmon and trout as well as having potential effects on chalk river flora. Figure 3.7.1 shows the location of the main structures for water level control in the Lower Test Valley, and the sections below provide further detail regarding the structures present in the Lower Test. The majority of these structures are logged on the Environment Agency‟s asset register, called the National Flood and Coastal Defence Database (NFCDD). Each structure on the register has a numeric identification tag e.g. Structure 1417; for ease of reference, this report uses the NFCDD ID number for each structure.

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The main structures on the Great Test are located at Testwood Mill and Nursling Mill (see Figure 3.7.1).

3.7.1.1. Testwood Mill A number of structures control the flow of water through Testwood Mill. These structures are shown in Figure 3.7.1 and described in Table 3.7.1. Figure 3.7.2 shows the layout of the structures at Testwood Mill and Pool, and Figure 3.7.3 details of the dimensions and levels of all the structures; this information has been taken from drawings obtained from the Environment Agency, supplemented by surveys undertaken specifically for this NEP study. Structures 1860, 1869 and 1870 all flow into Testwood Pool (Figure 3.7.1). Water levels in Testwood Pool do not typically drop below approximately 0.879 m OD which is the retention level of the riffles below the bridge as shown in Figure 3.7.2. The Testwood Mill structures impound water levels in the river for a significant distance upstream, see Section 5.1. It is not currently known precisely how these sluices are operated although during periods of low flow, a minimum aperture of 0.3 m in each hatch in Structure 1870 (known as the triple hatches) is required to ensure the passage of salmon upstream (Environment Agency, pers. comm.).

Table 3.7.1 The structures at Testwood Mill

ID Description

Structure 1867 Single, bottom opening penstock (Figure 3.7.4a). Well oiled spindle indicative of frequent use.

Fixed overspill weir and 8 bottom opening penstocks. Spindles on penstocks suggest they are Structure 1869 operated, however these are typically kept shut during the summer months based on field observations during 2011

3 x bottom opening penstocks (Figure 3.7.4b). Main flow of water through Testwood Mill during Structure 1870 summer 2011.

Two motorised bottom opening gates (Figure 3.7.4c). Two apertures in left hand gate; one is Structure 1860 permanently open as a fish pass, the other has a penstock attached to it (Figure 3.7.4d).

Alaskan Fish pass 0.5 m wide fish pass leading to area enclosed within corrugated iron sheets (Figure 3.7.4e).

Overflow sluice Bottom opening hatch between fish passes and triple sluices.

3.7.1.2. Nursling Mill A number of structures control the flow of water through Nursling Mill, see Figure 3.7.5, and also impound water levels for a considerable distance upstream:  The main structure is an array of eight metal hatches (Figure 3.7.5a) listed as Structure 1488 in the Environment Agency NFCDD Asset Register. Throughout the summer of 2011 only a single hatch was open;  Flow passes through a fish pass that is adjacent to the hatches (Figure 3.7.5b). Both the hatches and fish pass flow to a large pool upstream of the Nursling fish counter (see Section 6);  There is a historic offtake from the River into the Nursling Fish Farm on the right hand side of bank adjacent to the Mill building. This is an abstraction point for a non-consumptive licence, licensed to take 0.52 m3/s (45 Ml/d) from the Great Test. Flows into the fish farm are regulated by means of a metal plate; the metal plate has been lowered and only leakage under the gate flows into the Fish Farm (Figure 3.7.5c). Flows through this structure used to feed the Nursling Fish Farm and the Lower Test meadows. The Environment Agency have indicated that flow of water to the fish farm and meadows has been progressively reduced from approximately 0.52 m3/s (45 Ml/d) pre-2000, 0.13 m3/s (11 Ml/d) over 2000–2009 and 0.06 m3/s (5 Ml/d) thereafter (see Section 3.5); and  Water also flows through a structure under the Mill building (Figure 3.7.5d) (Structure 1457).

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3.7.2. Middle Test

A single structure controls flows from the Great Test into the Middle Test. Structure 1417 is located some 500 m upstream of Testwood Mill, on the left (eastern) bank of the Great Test, see Figure 3.7.5. This structure consists of a concrete headwall fitted with three bottom opening penstocks operated by ratchets (Figure 3.7.6). The structure is generally in a poor state of repair and it is unlikely that the penstocks can be operated safely at present. However, the structure acts as a barrier for the flow of water out of the Great Test into the Middle Test. Structure 1417 controls flow of water through the Middle Test. It is believed that the Middle Test may originally have been the main channel, and that construction and operation of the structure has enabled a change so that the majority of water is kept in the current Great Test channel. The structure has been kept shut recently (as reported in Environment Agency 2011c) and freshwater flows move into the Middle Test via two breaches in the riverbank adjacent to the structure (Figure 3.7.6b). There is an additional breach further downstream, between Testwood Mill and Structure 1417 (Figure 3.7.6c), which flows more intermittently7. There are no structures controlling water levels along the Middle Test itself, and water levels in this channel are predominantly tidally-controlled. At low tide, freshwater flows down the most upstream end of the Middle Test, thereafter flowing eastwards along the course of an old meadow carrier/ditch (Figure 3.7.7). The lower reaches of the Middle Test are heavily overgrown (Figure 3.7.6d) and have promoted the development of an alternative flow pathway from Structure 1417 towards the Little Test rather than down the Middle Test (Figure 3.7.7).

3.7.3. Little Test

The upstream end of the Little Test is located at NGR 435475 115963 where the River Test splits into two main channels, with the Great Test flowing to Nursling Mill to the west and the Little Test flowing along the eastern side of the valley. Four structures of note have been identified along the Little Test based on their ability to currently or historically influence the water level regime of this watercourse, see Figure 3.7.8.  Flows into the Little Test are controlled by Structure 1489 consisting of three individual hatches approximately 1 metre in width. The hatches are in a workable operation (Environment Agency, 2009a) and are owned, maintained and managed by the Barker Mills Estate as part of the „Coleridge Award‟. It is understood that there is currently no formal operating protocol for this structure, an operated on an ad-hoc basis by the lessee during weed cutting and other activities. For example, photographs in 2009 shows two hatches open (Environment Agency, 2009a) whereas recent field visits show that only a single hatch was open (Figure 3.7.8a).  The Environment Agency asset register shows a structure (1458) downstream of Conegar Bridge (Figure 3.7.8b). This location comprises a number of structures including a fish pass and a series of hatches. It was historically possible to feed the Lower Test meadows from this location but the hatches feeding the meadow do not appear operable and no flow was observed to flow through them during site visits for this NEP study in 2011 and 2012. The blocked hatches are the historic feeds to

7 Flows recorded during a survey visit of the breach (27/08/2009) 08.2009 reached 0.041 m3/sec (3.5 Ml/d)

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3.7.4. Meadow structures

There are a number of historic structures in the meadows located between the Great and Little Test, see Figure 3.7.9. Three main structures have been identified during walkover surveys and are described by the Environment Agency (2011d). All three structures are in a poor state of repair and appear to have been abandoned. Water meadow structures would have historically enabled flows from the Little Test to be directed towards one or another of the main historic meadow channels of the Lower Test Valley (Figure 3.7.7). Meadow channels could also be fed from Nursling Mill. Water from the Great Test or Little Test would be fed to a main distributary from where the water could be fed into various interconnected meadow, ridge and furrow systems (Figure 3.7.10). For the NEP investigation walkover surveys were undertaken to assess the main flow of water across the meadows (see Section 7.6 and Figure 7.6.1). Based on visual observations, some of the water from Nursling Fish Farm flows southwards and back into the Great Test as intended, but a significant proportion of this water flows along this preferential pathway away from the Great Test towards the Little Test. Contemporary Environment Agency spot flow gauging indicates a flow of 0.125 m3/s (10.8 Ml/d) at the outflow of the meadow system. Water levels in the main ditches of meadow system 1 (see the pink line on Figure 7.6.1) are maintained by water backing up from the Little Test. The presence of terrestrial vegetation within the channels leading from the Little Test to the main Meadow carriers and the growth of shrubs in the ley of the structures suggest these are no longer operated.

3.7.5. The Coleridge Award Structure

Almost all of the water control structures in the Lower Test are in private ownership. The only significant structures in the Lower Test Valley that are owned and maintained by the Environment Agency are hydrometric monitoring installations at Testwood Bridge, and at Broadlands, and Structure 1867 which is one of the four structures controlling the passage of water through Testwood Mill (see Section 3.7.1.1). A historic agreement called the „Coleridge Award‟ governs the ownership, maintenance and management responsibility regarding the structure at Conagar Bridge that controls the flow split of the Great and Little Test channel in the Lower Test valley. The agreement is binding in law and is transferrable to heirs or lessees of the original signatories of the agreement. The main components of the award are:  Ensure that at least two thirds of water in the main River Test flow along the Great Test to Nursling Mill, and not more than one third through the hatches of the Little Test; and  Hatches at Conagar, the Middle River and Testwood Mill should be kept in a thorough state of repair.

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3.8. Geomorphology

3.8.1. Introduction

A geomorphological reconnaissance survey was undertaken on the River Test on the 24th August 2011 to inform the understanding of the geomorphological dynamics of the study reach of the NEP. The geomorphology survey was conducted between Nursling Mill (SU 3518815728) and a large pool downstream of the road bridge, see Figure 3.8.1. This covers a channel length of approximately 2.5 km. The survey length was divided into five sub-reaches for recording purposes as shown in Figure 3.8.1, details of each are provided in Table 3.8.1. Typical sections, and particular features, are illustrated in Figure 3.8.1. The assessment provides an initial understanding of the geomorphological dynamics of the NEP study reach. The study comprised a desk study of available information and a one-day qualitative site walkover to assess the present modifications and sediment dynamics of the study reach. The approach is based on the standardised geomorphological reconnaissance survey techniques as detailed in the updated Guidebook of Applied Fluvial Geomorphological Techniques (Sear et al., 2010) and the Stream Reconnaissance Handbook (Thorne, 1998).

Table 3.8.1 Geomorphology survey reaches on the River Test

Survey Reach Code Top NGR Bottom NGR Reach Extent (m)

1 SU 35188 15728 SU32501 15413 352

2 SU32501 15413 SU35506 15183 368

3 SU35506 15183 SU35941 15064 543 4 SU35941 15064 SU36107 14477 957

5 SU36107 14477 SU 36336 14116 315

Note: Due to access constraints the location of the end of reach 1 and start of reach 2 were delineated using desk study information

3.8.1.1. Objectives The overall aim of the assessment is to provide an understanding of the geomorphology of the lower River Test in the reaches around NEP study area including Testwood Pool. Specific objectives were to:

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2. Identify factors that currently affect the reach; and

3. Identify broad improvements that could be made within the reach to improve the geomorphological quality of the system and offer habitat improvements.

3.8.2. Assessment

3.8.2.1. Desk study A review of historic channel change was undertaken as part of the overall assessment. An assessment of the 1871/72 map of the area suggests that the original course of the Lower River Test flowed through Charney meadows down to the estuary. The straight section from the diffluence of this small channel (see Figure 3.8.1), which is still present today, is in fact a man-made cut channel down to the Testwood Mill.

3.8.2.2. Site survey The Lower River Test system from Nursling Mill to the large pool downstream of the road bridge, has been significantly modified by the construction of the mills, associated weirs, new channel cuts, channel straightening, off-take structures and gauging weirs. However, at the upper and lower limits of the study reach more natural sections exist which are less modified and possess well established pool-riffle sequences. The structure at Testwood Pool marks a significant barrier to tidal water moving upstream.

3.8.2.3. River characteristics of Reaches 1–5 The NEP study area has been divided into five reaches based on predominant geomorphological characteristics. The results of the geomorphological survey are shown in Figure 3.8.1 with selected photographs shown in Table 3.8.2a–e. Figure 3.8.2 shows the location of all photographs taken, with Figure 3.8.3 presenting the photographs in full. Note that any references to “left” or “right” refer to a person standing with his or her back to the headwaters, and looking downstream. The reaches can be described as follows:  Reach 1: Nursling Mill to the start of straightened section upstream of Testwood Gauging Station (Table 3.8.2a) This is a semi-natural reach recovering from previous modification with evidence of bank erosion, deposition and a good pool-riffle development (see Table 3.8.2a). The left channel downstream of the mill has a good gravel substrate and a good mix of light and shade. The bridge downstream of the mill is a constriction leading to the development of a large scour pool.  Reach 2: Start of the straightened section upstream of Testwood Gauging Station to the confluence of River Blackwater (Table 3.8.2b) This reach has been previously straightened. This is possibly as a result of construction of the Testwood Gauging Station and the raw water intake to the Testwood WSW. The channel is uniform and lacking in any in-stream diversity. A backwater exists within the reach which is caused by the gauging station.  Reach 3: Confluence of River Blackwater to the start of sharp bend upstream of Chadney Meadow (Table 3.8.2c) The Blackwater was highly turbid on the day of the survey. It is likely that the river brings with it a significant volume of fine sediment into the Lower Test. Immediately downstream of the confluence, near Testwood Bridge, is the start (or most upstream location) of the backwater effect created by the structures at Testwood Mill and the tidal influence. The reduction in energy within this reach, and also in Reach 4, causes deposition across the whole bed of the channel which increases with distance downstream. Evidence of old riffles were still observed in Reach 3 but remain drowned out by the backwater effect from the structures at Testwood Mill. Embankments start to become increasingly evident in this reach particularly along the right bank.

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Table 3.8.2a Reach 1 summary of geomorphological characteristics

Reach 1: Nursling mill (SU 35188 15728) to start of a straightened section upstream of gauge (approx SU 35201 15413)

 This is a semi-natural reach that is recovering from previous modification  The leat from mill was surveyed in this study as no access existed for the main channel around the fish farm  Leat was cut in a straightened form but it is slowly developing instream diversity through preferential deposition  A weir pool existed at the start of the reach downstream of the off-take structure Natural pool-riffle sequence downstream of mill  A good pool-riffle development was evident throughout the reach particularly downstream of the confluence of the leat and the main channel Riffle upstream of bridge  There is a good mix of shaded sections and more open areas along the reach  Downstream of the bridge (near Testwood lakes) a deep pool has developed through the constriction of flow at the structure leading to scour downstream  Large fish were observed within the scour pool on the day of the survey

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Table 3.8.2b Reach 2 summary of geomorphological characteristics

Reach 2: Start of a straightened section upstream of gauge (approx SU 35201 15413) to the confluence of River Blackwater (SU 35506 15183)

 The reach has been previously straightened and Straightened section of this is potentially related to either, or both, the channel Environment Agency Testwood Gauging Station, and the off-take for the water supply to the pumping station  Channel is uniform and homogenous, lacking any instream diversity  Evidence of bank slumping along the right bank at the upstream section of the reach potentially caused by the river adjusting to previous straightening Bank slumping  The left bank is well vegetated whilst there are only small isolated pockets of trees along the right bank

 Extensive bank protection exists along the left bank Off-take structure which is associated with the pumping station and the Testwood Gauging Station

 Bank protection is limited along the right bank in the Straightened area immediately up and downstream of Testwood section by gauge gauging station  Water is generally flowing slower than in Reach 1 as a result of the ponded section upstream of Testwood gauging station

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Table 3.8.2c Reach 3 summary of geomorphological characteristics

Reach 3: Confluence of River Blackwater (SU 35506 15183) to the start of the sharp bend upstream of Chadney Meadow (SU 35941 15064)

 The confluence of the River Blackwater and the Confluence of the River Blackwater River Test marks a significant change within the and the River Test River Test as the Blackwater drains a different geology and is known to provide a higher proportion of fine sediment into the system  The River Blackwater was turbid on the date of the survey  Immediately downstream of the confluence, near Testwood Bridge, marks the start (or upstream extent) of the backwater which is created by the structures at Testwood Mill

 Localised narrowing of the channel has occurred Overhanging trees within the upper section of the reach leading to changes in localised hydraulics  Overhanging trees were interacting with the river leading to changes in localised hydraulics  Invasive species (Balsam) becomes commonplace, particularly along the right bank  The Balsam has been mown in some locations

Narrowing in upper section of reach 3

 The embankments start to become increasingly Slight embankment evident along evident particularly along the right bank the right bank  Much of the right bank was mown downstream of the pumping station to Testwood Mill leading to the development of a limited riparian corridor along this ban  Overall there is less vegetation along the right bank

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Reach 3: Confluence of River Blackwater (SU 35506 15183) to the start of the sharp bend upstream of Chadney Meadow (SU 35941 15064)

 The reduction in energy within this reach, and also Mown path in Reach 4, causes deposition across the whole bed of the channel which increases with distance downstream  Evidence of old riffles were still observed in within this reach but remain drowned out by the backwater from the structures at Testwood Mill  Macrophyte growth across the width of the channel becomes more evident within Reach 3 Drowned out riffle

 The channel is evidently becoming wider Drowned out riffle throughout Reaches 3 and 4

Wide section of channel backed up from structure at end of reach 4

Table 3.8.2d Reach 4 summary of geomorphological characteristics

Reach 4: Start of sharp bend upstream of Chadney Meadow (SU 35941 15064) to structures at Testwood Mill (SU 36107 14477)

 The reduction in energy within this reach causes Bank protection at bank toe deposition across the whole bed of the channel which increases with distance downstream  Reach 4 starts to become deeper than Reach 3 with increasing volumes of instream macrophyte growth  Bank protection was observed at the toe of the right bank at the start of the sharp bend

 Much of the channel is straight and it is believed, at some stage, to have been an artificial cut as the original channel appears to have flowed through

Chardney Meadow at the current diffluence of a small side channel

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Reach 4: Start of sharp bend upstream of Chadney Meadow (SU 35941 15064) to structures at Testwood Mill (SU 36107 14477)

 The embankment is increasingly evident, and Abundant instream becomes higher, along the right bank. It is also vegetation growth starts to become prominent along the left bank although it is significantly lower on this side of the channel  Much of the right bank has been mown reducing the ecological diversity of the riparian corridor

 Macrophyte growth across the width of the channel Narrow riparian is commonplace within Reach 4 corridor, mown grass behind

 Fishing platforms frequently extend into the river along the right bank throughout Reach 4 Heavily ponded section upstream of structures at Testwood Mill  Flow is imperceptible throughout the reach i.e. the river is very sluggish

Heavily ponded section upstream of structures at Testwood Mill

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Table 3.8.2e Reach 5 summary of geomorphological characteristics

Reach 5: Testwood Mill (SU 36107 14477) to the large pool downstream of the road bridge that enters the Testwood Mill (SU 36256 14171)

 There are a number of weirs and sluice structures that allow water through to Testwood pool at the mill structure. Recent modifications to these structures have been made to enable fish passage for a variety of species (Environment Agency, pers. comm.)  Sheet piling extends around the length of Testwood Pool to the bridge downstream

 Leat exists along the right side of Testwood Pool Pool downstream of rejoining the main channel downstream of the structure, upstream of the bridge bridge

 A rock weir exists immediately downstream of the bridge. This was potentially installed to ensure that the water levels are set continually high upstream of the structure

Rock weir downstream of bridge

 At the lower limit of the mill leat an old weir seems Lowered section of weir at end to have been lowered, potentially to aid fish of mill channel migration.

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Reach 5: Testwood Mill (SU 36107 14477) to the large pool downstream of the road bridge that enters the Testwood Mill (SU 36256 14171)

 Downstream of the confluence of the leat, the Lowered section of weir at channel has started to adjust to previous end of mill channel modifications  An old course is evident along the left bank of Testwood pool downstream of the bridge.  A pool-riffle sequence has become well established within this section of the reach  Bank erosion was also evident at various locations as the channel adjusts towards a more sinuous form Riffle – pool sequence

 Evidence of steep outer banks and gently sloping Riffle – pool sequence inside of the bends were prevalent throughout this part of the reach

Gently sloping inside of the bend

 Downstream of the constriction at the lower bridge Bank erosion on bend a large scour pool has developed. This has led to apex re-distribution of gravels and the formation of a large mid channel bar immediately downstream  A small channel, which bifurcated immediately upstream of the bridge, rejoins the main channel alongside the mid-channel bar

Mid-channel Weir pool bar

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3.8.2.4. Cross-sectional assessment A cross-sectional assessment of the Great Test between Testwood Mill and Nursling Mill was undertaken in November 2011. The dimensions of a total of 38 cross-sections were measured using an Environment Agency boat-mounted Acoustic Doppler Current Profiler (ADCP) (see Figure 3.8.4) cross-referenced with measured water level elevations at the time of survey. The locations of the cross-sections are shown in Figure 3.8.5; the resulting cross-sections are shown in Figure 3.8.6; and a longitudinal profile of the Lower River Test is shown in Figure 3.8.7. The river between Testwood Gauging Station and Testwood Mill is impounded. At the time of the survey water levels at Testwood Mill were between 2.1 and 2.6 m AOD. Comparison of this water level relative to the cross-sectional and longitudinal dimensions of the river reach show that, under steady state conditions, this would submerge part or all of every cross-section surveyed, including Testwood Gauging Station which is a noticeable feature and shown as a thick black line in Figure 3.8.6a; a photograph of the weir is shown in Figure 3.8.6b when water levels were low due to the operation of water level structures; Figure 7.3.4 (c) shows the hydrological effect of the weir at a higher water level. The results show that, in hydrological terms at least, the Lower Test exhibits lacustrine characteristics and more closely resembles a lake than a river, with slowly moving water. The cross-sectional assessment shows that the impoundment caused by Testwood Mill could extend up to 1.7 km upstream including parts of the river upstream of the Testwood Gauging Station (cross-sections shown as the dotted lines in Figure 3.8.6). These results support survey observations of (a) the considerable upstream extent of tidally-induced water level variations (Section 3.6) and (b) the ecological signature of the reach dominated by aquatic species more common of lentic, sediment rich lowland rivers, rather than chalk stream habitats (Section 2.3). Historic information found in the county archives indicate plans to dredge the river bed during the post-war period although it is unclear from available documentary evidence whether this was ever undertaken. However, the cross-sectional character does provide a strong indication that the river planform has been modified at some time in the recent past.

3.8.3. Conclusions

The reach of the River Test under investigation for the NEP has been heavily modified for mills (and the associated infrastructure), water resources and for gauging. The structures at Testwood Mill have the most significant effect in the study reach through the creation of a large backwater upstream of these impoundments. More natural sections of channel were evident in Reaches 1 and 5 which were less impacted by modifications and exhibited free flowing conditions. A well established pool-riffle sequence has developed in both these reaches. In summary, the overall geomorphological characteristics of the surveyed watercourse are as follows:  Much of the length of the channel surveyed is heavily modified. This is particularly the case for Reaches 2 and 3 which are large ponded sections due to the backwater effects of Testwood Mill. They are both significantly embanked particularly along the right bank. Much of the river around Testwood Mill is bank protected;  Reaches 1–5 all have a good mix of shaded and open sections. Mature trees are evident along the bank throughout the reach. The main fishing access route within Reaches 3 and 4 is the most heavily managed section of channel; the management is restricted to the right bank which possesses a limited riparian corridor between the mown corridor and the bank edge;  The channel has been significantly modified for milling, water abstraction and gauging;  The best aquatic habitat was found within Reach 1 (non-tidal) and Reach 5 (tidal) which are free flowing and are not affected by backwater effects. These more-natural sections contain well established pool-riffle sequences and the channel has started to recover from previous modification leading to the development of a more sinuous form (particularly evident in reach 5);  The natural channel width is around 15–20 m wide;

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Atkins 63 CD Copy 3/10: Louise Bardsley, Natural England

This section describes the numerical models used to simulate the study reach in the NEP investigation. Models are required in order to explore the effects of different abstraction scenarios upon physical and biological factors such as velocities, water levels and salmon migration. In addition, the effects of other influencing factors can be explored such as the tidal regime and structure management. Four different models are discussed in the following sections:  Infoworks hydraulic model;  A bespoke wetland model;  Atkins‟ Thermal Model; and  Salmon Movement Model.

4.1. Infoworks Hydraulic Model

4.1.1. Introduction

A hydraulic model of the Lower River Test has been constructed in order to assess the effects of abstraction upon river levels within channel under low flow conditions. The model represents the characteristics of the study reach. The upstream extent of the model is the Testwood abstraction point; the downstream extent of the model is the Testwood Pool; a complex series of structures control the outflow from the River Test into the Testwood Pool. A location plan showing the extent of the model is shown in Figure 4.1.1.

4.1.2. Model Construction

The hydraulic model is a one-dimensional (1D) model constructed using Infoworks RS v11.5.6. The model was constructed using Infoworks as it allows for easy adaptation of the model and inclusion of 2D elements if required. Data The model of the Lower Test has been constructed twice, firstly using historic data of channel characteristics, and secondly using data collected specifically for the NEP investigation. The model was constructed originally with cross-sectional survey data from the 1940s as it seemed that more recent data was not available. Historic data were gathered from paper records and microfiche. These data were digitised and used to create the river channel cross sections in the model. While a model was constructed and successfully tested, using such historic data, rather than contemporary data,could mean the results were not relevant to the current geomorphology for the channel. Therefore for the purposes of the NEP investigation, the Environment Agency collected additional cross section data in October 2011 using a boat equipped with an Acoustic Doppler Current Profiler (ADCP). The ADCP returns water depths at locations across the river channel and when used in conjunction with survey of river water level, it can be used to create surveyed river channel cross sections. This survey data was used to create an improved version of the Lower River Test model. The two versions of the survey data showed considerable variation in river bed level between each other; this is not surprising given the significant changes in channel morphology likely to have taken place in the 60–70 years between the two sets of data. Light Detection and Ranging (LiDAR) data, obtained from the Environment Agency, has also been used for construction of the hydraulic model. The model was initially unstable during periods of higher flows however, this was rectified by extending the sections into the floodplain using LiDAR data. Structures

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4.1.3. Boundary Conditions

Fluvial Inflows The fluvial inflows into the hydraulic model were obtained from observed flow data, described in section 3.5. Tidal Boundary Conditions A tidal time series has been included as the downstream boundary of the model. Observed data from the Environment Agency tide gauge at Eling Mill was considered was investigated; however, there were some significant data gaps which precluded its use for the long term operation of the model. As a result, long term time-series were generated using the standard simplified admiralty method and the harmonic constants given in the Admiralty Tide tables (United Kingdom Hydrographic Office, 2010).

4.1.4. Model Run Parameters and Performance

The hydraulic model can be run with an adaptive time-step and runs quickly. It is possible to simulate 1 years worth of river flows in minutes, permitting long term simulations to be performed. The calibration of the model is presented in Appendix 4.1.1 and shows that the model is of sufficient accuracy for the purposes of the NEP investigation.

4.2. The Wetland Model

Water table fluctuations within the Lower Test Valley SSSI have been modelled using an adaptation of a published water table model (Armstrong, 1993; Armstrong and Rose, 1998; and Swetnam et al., 1998). The model is one dimensional and was chosen for its simplicity and limited data demands. It has been used in a number of wetland applications as it is based on sound theoretical principles which can be adapted to fit the particular characteristics of the site under investigation. For the Lower Test NEP, the use of the wetland model has important advantages. It:

 Includes an explicit representation of the properties of the stratigraphy underlying the Lower Test Valley SSSI;  Represents the influence of rainfall, evaporation, ditch water levels and tidal variations on an hourly basis;

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Within the water table model, the water table elevation is estimated as a function of the water table elevation in the preceding time-step by consideration of precipitation, evaporation, discharge to or from watercourses, the soil specific yield, the level of the ditches, the soil hydraulic conductivity and the distance between the location where the water table elevation is to be estimated and the closest watercourse.

The model assumes that there is no soil moisture deficit. This assumption is commonly used in groundwater models for riparian and wetland areas where the water table is permanently close to the surface.

Further information on the model is presented in Appendix 4.2.1. The use and outputs of the model is described in Section 7.6.

4.3. The Thermal Model

4.3.1. Introduction

Increasing attention has been paid in recent years to the potential effect of solar heating on the thermal regime of water bodies on fisheries and other aquatic species, with respect to reduced flows through climate change, abstraction for public water supply of wetland creation (such as using former water meadow carriers for wetland creation or restoration). Atlantic salmon population are already thought to be close to the upper limit of their thermal tolerance in southern chalk streams and there is concern that, with the risk posed by future climate change, no additional risks to the thermal regime of the River Test are created. A model for aquatic heating in lakes and steadily flowing channels developed by Atkins has been applied for the NEP investigation. The aim of the work is to simulate the thermal balance in the river reach under focus to ascertain the possible magnitude of temperature changes in the main river under different abstraction scenarios.

4.3.2. Atkins‟ Aquatic Heat Model

The Atkins‟ Aquatic Heat Model (AQHM) was developed to simulate the heat balance in slowly moving water bodies such as lakes and docks as well as streams. The model has been used in a number of different applications in the UK and overseas. The model includes the effects of shading and a full description of the surface heat transfer which, in broad terms, is a function of air temperature, wind speed and direction, relative humidity and cloud cover. The distribution and shape of foliage is modelled with appropriate view factors. The model focuses on the thermal balance and heat transport in the river as a function of riparian shading. Both trees and shrubs as means of providing shade can be simulated. In particular the sensitivity of the downstream temperature gradient has been investigated as a function of:  Stream flow;  Shading type (shrubs or trees);  Stream orientation;  Variation in wind speed; and

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4.4. The Salmon Movement Model

In 2009, the EA appointed Pisces Conservation Ltd (as part of its Lower Test project, see Section 1.2.1) to analyse the relationship between the historic salmon count data, river flow and water temperature with a view to exploring the feasibility of developing a statistical model to simulate salmon movement in the Lower Test. Pisces concluded that there was scope for the development of such a model. The Scoping Stage of this NEP study reviewed the existing data, analysis, modelling and recommendations pertaining to the proposed salmon movement model, and it was concluded that a model would be a useful tool for the NEP study. Therefore the procurement of the model was undertaken as part of the Investigation. The use and outputs of the model is described in Section 6.

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This chapter sets out the findings from the monitoring and modelling assessment undertaken to understand the hydrological regime of the Lower Test. Section 5.1 details an assessment of water levels in the study reach using Environment Agency permanent monitoring devices plus ones deployed for the NEP investigation. Section 5.2 presents the outputs of the hydraulic model (see Section 4.1) that has been used to examine the influences upon the Great Test of the Testwood abstraction, tidal regime and management of structures. The conclusions of the monitoring and modelling work are presented in Section 5.3.

5.1. Water level monitoring

5.1.1. Introduction

The NEP investigation has used routine water level, and other monitoring data, from the Great Test, Little Test and Middle Test to assess the factors controlling the hydrology of the lower reaches of the River Test. In addition, observations have been made on site visits during spring tide periods of the extensive tidal flooding of the Lower Test Valley SSSI and within the lower reaches of the River Test more generally (see Figure 5.1.1). Historic water level data and the results of water level monitoring between October 2011 and January 2012 have been analysed to assess the influence of tidal fluctuations on the hydrology of the Lower Test.

5.1.1.1. Monitoring locations Three Environment Agency monitoring locations have been used as part of the assessment (Table 5.1.1). In addition, six temporary water level monitoring locations have been installed as part of the NEP investigation (see Table 5.1.1). The monitoring locations are shown in Figure 5.1.2. Figure 5.1.2 also shows the location of the Testwood abstraction and other features of note such as water control structures. Figure 5.1.3 shows photographs of the different water level monitoring locations used as part of the study. The tidal gauge at Eling Mill is located in Southampton Water, approximately 2.2 km downstream of Testwood Mill. The Testwood Gauging Station is located just downstream of the Testwood abstraction and 1.65 km upstream of Testwood Mill. Testwood Bridge is located downstream of the confluence of the River Test and the Blackwater, some 1.3 km upstream of Testwood Mill. Temporary water level loggers have been installed in Testwood Pool and upstream of Structure 1869 (see Figure 5.1.2) in Testwood Mill to assess the influence of tidal water level fluctuations on flow through the Mill structures. Temporary water level loggers have also been installed on the upstream and downstream sides of Structure 1417 to provide an equivalent assessment at this location. A water level logger has also been installed in the Little Test (Figure 5.1.2, Table 5.1.1).

5.1.1.2. Approach As part of the assessment, water level data for the monitoring locations described in Table 5.1.1 have been compared. The assessment has focussed on the period between 1st October 2010 and 6th January 2012 when telemetered water level monitoring equipment was deployed on site.

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5.1.2.1. Testwood Gauging Station As stated in Section 3.6 the Testwood abstraction is sited at the natural hydraulic limit of the tide, and the structures at Testwood Mill and the broad crested weir at Testwood GS prevent the upstream influx of tidal water but a backwater effect occurs through tidelocking. Water levels at the Testwood Gauging Station show short-term responses due to rainfall superimposed upon a water level regime dominated by groundwater baseflow. Baseflow water levels varied little, with maxima in February–March and minima in October–November. Figure 5.1.4 shows water level data for Eling Tide Mill and Testwood gauging station from March to April 2011. Data from Eling Tide Mill show the typical twice daily tidal fluctuations evident in the Solent superimposed upon distinct spring-neap tidal cycles. Throughout the monitoring period, water levels in the River Test remained above tidal levels, even during extreme surge events (Figure 5.1.5), indicating that any tidal influence on the study reach is likely to be indirect, by affecting the rate of flow through the Testwood Mill sluices by slowing it down or reducing it to zero (tide locking). Water levels at Testwood Gauging Station show a distinct response to tidal water level fluctuations. This is especially apparent during spring tide periods (Figure 5.1.4); water levels at the gauging station rise and fall by approximately 0.10 m to 0.15 m on the peak of each spring tide. Comparison of water levels from the Testwood Gauging Station and Testwood Bridge (Figure 5.1.6) show that tidally-induced variations upstream and downstream of the Blackwater confluence are of a similar magnitude. Figure 5.1.5 shows the clear influence of the tide upon water levels on the Lower Test during a tidal surge recorded on the 28th November. During this event, a high spring tide water level of 2.37 m OD at Eling Tide Mill resulted in a water level increase of 0.25 m at Testwood Gauging Station (Figure 5.1.5).

Table 5.1.1 Environment Agency, and temporary, monitoring locations used in the NEP investigation

Monitoring location Record Easting Northing Parameters Name EA Number duration Eling Tide Mill 151600001 436,500 112,500 Water level Unknown Water level, 11/05/1987– Testwood GS 151816003 435,396 115,268 Discharge Current Water level, Discharge, 02/02/2004– Testwood Bridge 151816016 435,610 115,174 Velocity, 01/06/2010 Temperature

Testwood Pool 436,134 114,512 Water level, 02/11/2011– Temperature, Testwood Mill 436,112 114,495 06/01/2012 Conductivity

Structure 1417 436,146 114,977

Temporary – Middle Test 436,168 114,983 19/09/2011 present Little Test 436,717 114,974 Water level, Temperature River Blackwater 435,339 115,138 21/07/2011– present Nursling Mill 435,196 115,770

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5.1.2.3. Structure 1417 and the Middle Test Figure 5.1.7b shows the water level data for monitoring locations either side of Structure 1417, linking the Great Test to the Middle Test. Water levels upstream of Structure 1417 showed replicate water level variations to those recorded at Testwood Mill 0.5 km downstream with variations of up to 0.25 m during spring tides (Figure 5.1.7b). Water levels in the Middle Test responded strongly to the tides, with variations of up to 0.3–0.4 m during spring tides and 0.05–0.10 m during neaps. During low tide water levels fall to a relatively constant level of approximately 1.65 m OD representing the retention level of downstream debris dams that control water levels in this watercourse. As at Testwood Mill, water levels upstream of Structure 1417 remained above water levels in the Middle Test at all times during the monitoring period, maintaining a predominant direction of flow from the Great Test into the Middle Test. However, during the spring tide surge of 28th November 2011, water levels in the Middle Test were closely equivalent to water levels in the Great Test, indicating of potential intrusion of water entering the Great Test from the Middle Test during the highest tides of the year. In addition, monitoring has shown that the operation of sluices as far upstream as Conegar Bridge can affect flows over Structure 1417 and into the Middle Test. For example, the sluice operation event of 5th October 2011, as described in Section 3.7.5 resulted in a short-lived 0.40 m increase in water level in the Middle Test (Figure 5.1.7b) during the short-term 1.5 m3/s (129.6 Ml/d) flow increase in the Great Test (Figure 3.7.11b).

5.1.2.4. Little Test Figure 5.1.7(c) shows water level variations in the Little Test between 1st October 2011 and 6th January 2012. Figure 5.1.8c shows a close up for the month of November 2011. As with other water level monitoring locations, water levels in the Little Test varied with the tide. The magnitude of water level variations was similar to those recorded in the River Blackwater: these are shown in Figures 5.1.7c and 5.1.8c with water level variations of 0.01–0.02 m on each neap tide cycle and up to 0.1 m during spring tides. The largest change, as for most other locations, was during the spring tide surge of 28th November 2011 when a change of 0.15 m was registered.

5.1.3. Water quality: salinity

Tidal water level variations influence the water level regime of the whole of Lower Test, including locations upstream of the historic mill structures that represent flow boundaries. This tidal influence is indirect; observed water level variations at in the Great Test, Middle Test and Lower Test Testwood Gauging Station (Figure 5.1.7a) and Testwood Bridge are a hydraulic „backing up‟ effect caused by water flowing through the Lower Test structures during peak spring tide periods. There is a progressive decline in tidal influence with increasing distance upstream from the tidal influence. However, this difference is not the same for different branches of the Lower River Test. For example, tidally- induced water level variations in the Little Test at the footpath bridge, 1.8 km upstream of Redbridge, vary by

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5.2. Modelling the hydrological regime

The direct effect of different abstraction scenarios on flow in the Great Test has been discussed in Section 1.5.2, for the locations of Testwood gauging station and the MRF point (see Figures 1.5.2 to 1.5.7). This section describes the use of a hydraulic model which was developed as part of the NEP investigation (see Section 4.1) and can simulate flow volume, water velocity and water levels in the Great Test one an hourly timestep for the 15-year period between 1996 and 2011. The model is used here to examine the effect of the Testwood abstraction in the context of other significant factors (tidal regime and water level management structures) upon on the hydrological regime of the Lower Great Test. It also allows the spatial extent of these influencing factors to be examined, as the hydraulic model extends from the abstraction intake right down to Testwood Mill. It also allows for the factors of the tidal regime and the structure operation to be minimised, in order to assess the effects of the Testwood abstraction and structure management, against the context of the tidal regime. Flow, velocity and water level data have been extracted at five model Assessment Points (APs), shown in Figure 4.1.1, which are located at varying distances between the Testwood abstraction intake at the upstream end of the model, and Testwood Mill at the downstream end, to provide a spatially distributed assessment of the effects on the hydrological regime of the river under a range of scenarios. The outputs (data and charts) available from the use of the hydraulic model can be voluminous and so, for the purpose of reporting, only results from AP1, AP2, and AP4 are presented in the main body of the report. Results for the remaining Assessment Points (AP3 and AP4) are found in Appendix 5.2.1. AP1 shows the immediate downstream effects of the abstraction, and AP2 and AP4 are used to show the spatial extent of changes to the hydrological regime. AP1 is located at the upstream end of the study reach, approximately 145 m downstream of the Testwood abstraction, and upstream of both the Testwood Gauging Station weir and the confluence between the Great Test and the River Blackwater. AP1 is also located just downstream of the EA Testwood downstream macroinvertebrate sampling points (see Sections 2.4.1 and 7.3). AP2 is located approximately 305 m further downstream from AP1; 450 m downstream of the abstraction intake. It is located downstream of the in-stream barrier created by the EA gauging weir and the Blackwater confluence, and so the results from this Assessment Point will help to show the spatial extent of the effect of the abstraction. AP4 is located at the downstream end of the river reach of interest, approximately 350 m further downstream from AP2; therefore 800 m downstream of the abstraction intake. AP4 is just upstream of the Testwood Mill structures and the flow split into Testwood Pool. The three main abstraction scenarios (as described in Section 1.2) have been assessed as follows:  Naturalised i.e. no abstraction at Testwood;  Historic i.e. assessing the actual abstraction that has occurred; and

8 Where ppt indicates salinity as parts per thousand (‰, or permille) which is approximately grams of salt per kilogram of solution. As a guide, the average ocean salinity is 35 ppt, and freshwater salinity is usually less than 0.5 ppt. Water between 0.5 ppt and 17 ppt is called brackish.

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Tables 5.2.1a–i and Figures 5.2.1a–c present the results of the hydraulic model for flow volumes at different exceedance values under the different scenarios for Assessment Points 1, 2 and 4 over the 15 year study period. These figures and tables have been generated using hourly data from the entire modelling period. As stated above, these tables and figures show the results from all possible combinations of the two key factors: abstraction and structure settings and so careful interpretation is needed. In order to assess the effect of the abstractions, the model results pertaining to naturalised conditions will be examined first, and then the effect of the Testwood PWS abstraction. Therefore Figures 5.2.1d to i present the difference between the structure settings with naturalised abstraction (i.e. none) with regard to flow for 2006 and 2007, in order to highlight the magnitude and spatial extent of the structures and tidal regime over the representative dry and wet years. Figures 5.2.1j to q present the difference between the abstraction scenarios with regard to flow for 2006 and 2007, in order to highlight the magnitude and spatial extent of the abstraction. Finally Figures 5.2.1r to s show a combination of abstraction and structure settings to show the worst case scenario. The tables are grouped into a set of three (a, b, and c) for each assessment point: a–c for AP1; d–f for AP2 and g–i for AP4. The first table presents flow statistics for different structure settings, and different abstraction scenarios at AP1; the second table shows the difference between different abstraction scenarios, keeping the structure settings constant; finally, the third table shows the difference between different structure settings, keeping the abstraction scenario constant.

Using the above figures and tables, the effects of the tidal regime, structures and the abstraction on discharge at Assessment Points 1, 2 and 4 can be described as follows:  At all assessment points, discharges were highest under the naturalised scenario and lowest under the fully licensed scenario, reflecting the volume of water that has been abstracted;  Figures 5.2.1a–c show that discharges at AP1 are suppressed due to the Testwood abstraction, but show an increase at AP2 which is due to the inputs of water from the Blackwater system and the Nursling take. Flows are reduced at AP4 again at the higher end of the regime due to the loss of water into the Middle Test where water flows into the channel either by overtopping the structure or via the breach. Discharge at low flows is comparable between AP2 and AP4 as the water level would be too low to activate the breach or for water to flow over the Middle Test structure.  Figure 5.2.1d–i show that the change in hydrological regime experienced in the main channel due to the effect of structure settings (with no abstraction) is considerable. The largest change is shown in Figure 5.2.1.e which shows the effect of the closed and fully open structure settings can make a difference in flow of between +4 m3/s, (346 Ml/d) and −2.5 cumecs (216 Ml/d) depending on the settings. The effect is particularly evident at Assessment Points 2 and 4, but negligible at AP1. The reason for these results is due to the tidal regime and the setting of the structures which affect the ability of the Great Test to discharge water depending on the position of the tide. Figures 5.2.1d–i shows that variation caused by the tide is pronounced during low flows (July to October 2006) and less evident during period of higher flows. Over November 2006 to April 2007, a period of high winter flows the trend, shown in the figures, changes for AP4. It is thought that the reason for this because under high flows the volume of water in the Great Test channel is such that the water level spills over the sill level of the breaches around the Middle Test structure, and so there is a loss of water from the Great Test channel of the River Test, into the channel of the Middle Test.  The spiky nature of the time series shown in Figures 5.2.1d–i (and 5.2.1j–q) show that flow at AP2 and AP4 is considerably subject to the tide‟s influence; but the effect at AP1 is much reduced. This shows that the effect of the tide, or rather its indirect effect of tide-locking, is felt for a considerable distance upstream; all the way to AP1. The reason why flows at AP1 are less affected is most likely due to the broad crested weir which, as it has a high crest elevation, effectively dampens the tidal signal from propagating further upstream.  Given that there is a pronounced tidal effect upon flows, the charts showing the results with structures-fully-closed are the best to illustrate the effects of the abstraction alone. Figure 5.2.1k

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Table 5.2.1a Flow discharges (Ml/d) at different exceedance values under the different scenarios for AP 1

Structures = closed Structures = partially open Structures = fully open Q- Fully Fully Fully Percentile Historic Naturalised Historic Naturalised Historic Naturalised licenced licenced licenced 5 1675 1759 1811 1675 1759 1811 1675 1759 1811 10 1295 1375 1432 1295 1375 1432 1295 1375 1432 50 496 572 632 496 572 632 496 572 632 80 230 305 367 230 305 367 230 305 367 90 158 233 295 158 233 295 158 233 295 95 126 190 262 126 190 262 126 190 262 98 91 161 228 91 161 228 91 161 228 The table above shows flow statistics for different structure settings, and different abstraction scenarios at AP1

Table 5.2.1b Difference between abstraction scenarios for flow discharges (Ml/d) at AP 1

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Difference Difference Difference Difference Difference Difference Q- between Full between between Full between between Full between Percentile Licence & Historic & Licence & Historic & Licence & Historic & Naturalised Naturalised Naturalised Naturalised Naturalised Naturalised 5 −136 (−8%) −52 (−3%) −136 (−8%) −52 (−3%) −136 (−8%) −52 (−3%) 10 −136 (−10%) −57 (−4%) −136 (−10%) −57 (−4%) −136 (−10%) −57 (−4%) 50 −136 (−22%) −60 (−9%) −136 (−22%) −60 (−9%) −136 (−22%) −60 (−9%) 80 −136 (−37%) −62 (−17%) −136 (−37%) −62 (−17%) −136 (−37%) −62 (−17%) 90 −136 (−46%) −62 (−21%) −136 (−46%) −62 (−21%) −136 (−46%) −62 (−21%) 95 −136 (−52%) −72 (−27%) −136 (−52%) −72 (−27%) −136 (−52%) −72 (−27%) 98 −136 (−60%) −67 (−29%) −136 (−60%) −67 (−29%) −136 (−60%) −67 (−29%) The table above shows the flow volume difference between different abstraction scenarios at AP1, keeping the structure settings constant

Table 5.2.1c Difference between structure settings for flow discharges (Ml/d) at AP 1

Table 5.2.1d Flow discharges (Ml/d) at different exceedance values under the different scenarios for AP 2

Structures = closed Structures = partially open Structures = fully open Q- Fully Fully Fully Percentile licensed Historic Naturalised licensed Historic Naturalised licensed Historic Naturalised 5 2256 2338 2393 2256 2338 2393 2256 2338 2393 10 1702 1786 1838 1701 1786 1838 1701 1786 1838 50 644 720 780 644 720 780 644 720 780 80 341 415 478 341 415 478 342 416 478 90 260 334 397 261 334 397 261 334 397 95 228 294 364 228 294 364 228 294 364 98 189 257 325 188 258 325 188 257 324 The table above shows flow statistics for different structure settings, and different abstraction scenarios at AP2

Table 5.2.1e Difference between abstraction scenarios for flow discharges (Ml/d) at AP 2

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NB For each pair of columns, the structure settings have been kept the same to allow the difference of the abstraction scenarios to be identified. The percentage change is indicated in brackets. Structures = closed Structures = partially open Structures = fully open

Difference Difference Difference Difference Difference Difference Q- between Full between between Full between between Full between Percentile Licence & Historic & Licence & Historic & Licence & Historic & Naturalised Naturalised Naturalised Naturalised Naturalised Naturalised 5 −137 (−6%) −55 (−2%) −137 (−6%) −55 (−2%) −137 (−6%) −55 (−2%) 10 −136 (−7%) −52 (−3%) −137 (−7%) −52 (−3%) −137 (−7%) −52 (−3%) 50 −136 (−17%) −60 (−8%) −136 (−17%) −60 (−8%) −136 (−17%) −60 (−8%) 80 −137 (−29%) −63 (−13%) −137 (−29%) −63 (−13%) −136 (−28%) −62 (−13%) 90 −137 (−35%) −63 (−16%) −136 (−34%) −63 (−16%) −136 (−34%) −63 (−16%) 95 −136 (−37%) −70 (−19%) −136 (−37%) −70 (−19%) −136 (−37%) −70 (−19%) 98 −136 (−42%) −68 (−21%) −137 (−42%) −67 (−21%) −136 (−42%) −67 (−21%) The table above shows the flow volume difference between different abstraction scenarios at AP2, keeping the structure settings constant

Table 5.2.1f Difference between structure settings for flow discharges (Ml/d) at AP 2

Difference Difference Difference between Difference Difference Difference between between Partially between between between Partially Q- Closed and Open and Closed and Partially Open Closed and Open and Percentile Fully Open Fully Open Fully Open and Fully Open Fully Open Fully Open 5 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 10 1 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 50 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 80 −1 (0%) −1 (0%) −1 (0%) −1 (0%) 0 (0%) 0 (0%) 90 −1 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 95 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 98 1 (1%) 0 (0%) 0 (0%) 1 (0%) 1 (0%) 1 (0%) The table above shows the flow volume difference between different structure settings at AP2, keeping the abstraction scenario constant

Table 5.2.1g Flow discharges (Ml/d) at different exceedance values under the different scenarios for AP 4

Structures = closed Structures = partially open Structures = fully open Q- Fully Fully Fully Percentile Historic Naturalised Historic Naturalised Historic Naturalised licensed licensed licensed 5 2102 2175 2223 2120 2194 2241 2161 2234 2282 10 1610 1685 1732 1628 1703 1749 1664 1742 1789 50 644 720 779 644 721 780 644 721 780 80 341 415 478 342 416 478 343 417 479 90 260 334 397 262 334 397 262 335 398 95 228 294 364 229 294 364 227 293 364 98 188 257 325 188 258 324 185 256 323 The table above shows flow statistics for different structure settings, and different abstraction scenarios at AP4

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NB For each pair of columns, the structure settings have been kept the same to allow the difference of the abstraction scenario to be identified. The percentage change is indicated in brackets. Structures = closed Structures = partially open Structures = fully open Difference Difference Difference Difference Difference Difference Q- between Full between between Full between between Full between Percentile Licence & Historic & Licence & Historic & Licence & Historic & Naturalised Naturalised Naturalised Naturalised Naturalised Naturalised 5 −121 (−5%) −48 (−2%) −121 (−5%) −47 (−2%) −121 (−5%) −48 (−2%) 10 −122 (−7%) −47 (−3%) −121 (−7%) −46 (−3%) −125 (−7%) −47 (−3%) 50 −135 (−17%) −59 (−8%) −136 (−17%) −59 (−8%) −136 (−17%) −59 (−8%) 80 −137 (−29%) −63 (−13%) −136 (−28%) −62 (−13%) −136 (−28%) −62 (−13%) 90 −137 (−35%) −63 (−16%) −135 (−34%) −63 (−16%) −136 (−34%) −63 (−16%) 95 −136 (−37%) −70 (−19%) −135 (−37%) −70 (−19%) −137 (−38%) −71 (−20%) 98 −137 (−42%) −68 (−21%) −136 (−42%) −66 (−20%) −138 (−43%) −67 (−21%) The table above shows the flow volume difference between different abstraction scenarios at AP4, keeping the structure settings constant

Table 5.2.1i Difference between structure scenarios for flow discharges (Ml/d) at AP 4

NB For each pair of columns, the abstraction scenarios have been kept the same to allow the difference of the structure settings to be identified. The percentage change is indicated in brackets. Fully licensed Historic Naturalised Difference Difference Difference Difference between Difference between Difference between between Partially between Partially between Partially Q- Closed and Open and Closed and Open and Closed and Open and Percentile Fully Open Fully Open Fully Open Fully Open Fully Open Fully Open 5 −59 (−3%) −41 (−2%) −59 (−3%) −40 (−2%) −59 (−3%) −41 (−2%) 10 −54 (−3%) −36 (−2%) −57 (−3%) −39 (−2%) −57 (−3%) −40 (−2%) 50 0 (0%) 0 (0%) −1 (0%) 0 (0%) −1 (0%) 0 (0%) 80 −2 (−1%) −1 (0%) −2 (0%) −1 (0%) −1 (0%) −1 (0%) 90 −2 (−1%) 0 (0%) −1 (0%) −1 (0%) −1 (0%) −1 (0%) 95 1 (0%) 2 (1%) 1 (0%) 1 (0%) 0 (0%) 0 (0%) 98 3 (2%) 3 (2%) 1 (0%) 2 (1%) 2 (1%) 1 (0%) The table above shows the flow volume difference between different structure settings at AP4, keeping the abstraction scenario constant

5.2.2. Effects upon velocities

Tables 5.2.2a–i and Figures 5.2.2a–c present the results of the hydraulic model for velocities under the different scenarios for Assessment Points 1, 2 and 4 over the 15 year study period. As discussed in Section 5.2.1, these tables and figures show the results from all possible combinations of the two key factors: abstraction and structure settings and so careful interpretation is needed. In order to try and assess the effect of the abstractions, the model results pertaining to naturalised conditions will be examined first, and then the effect of abstraction. Therefore Figures 5.2.2d–i present the difference between the structure settings with naturalised abstraction (i.e. none) with regard to water velocity for 2006 and 2007, in order to highlight the magnitude and spatial extent of the structures and tidal regime over the representative dry and wet years. Figures 5.2.2j–q present the difference between the abstraction scenarios with regard to velocity for 2006 and 2007, in order to highlight the magnitude and spatial extent of the abstraction. Finally Figures 5.2.2r to s show a combination of abstraction and structure settings to show the worst case scenario. The tables are grouped into a set of three (a, b, and c) for each assessment point: a–c for AP1; d–f for AP2 and g–i for AP4. The first table presents velocity statistics for different structure settings, and different abstraction scenarios at AP1; the second table shows the difference between different abstraction scenarios,

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Table 5.2.2a Flow velocities (m/s) at different exceedance values under the different scenarios for AP 1

Structures = closed Structures = partially open Structures = fully open V- Fully Fully Fully Percentile Historic Naturalised Historic Naturalised Historic Naturalised licensed licensed licensed 5 0.76 0.77 0.77 0.82 0.83 0.83 1.03 1.04 1.04 10 0.74 0.75 0.76 0.81 0.82 0.82 1.01 1.02 1.03 50 0.57 0.61 0.64 0.64 0.69 0.71 0.73 0.78 0.82 80 0.38 0.46 0.52 0.45 0.54 0.60 0.45 0.55 0.62 90 0.30 0.40 0.46 0.34 0.45 0.54 0.34 0.45 0.54 95 0.25 0.34 0.42 0.28 0.39 0.49 0.28 0.39 0.50 98 0.20 0.30 0.39 0.21 0.34 0.45 0.21 0.34 0.45 The table above shows the difference in water velocity for different structure settings, and different abstraction scenarios at AP1

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Table 5.2.2b Difference between abstraction scenarios for velocities (m/s) at AP 1

Difference Difference Difference Difference Difference between Difference V- between Full between between Full between Full Licence & between Historic Percentile Licence & Historic & Licence & Historic & Naturalised & Naturalised Naturalised Naturalised Naturalised Naturalised 5 −0.01 (−1%) 0 (0%) −0.01 (−1%) 0 (0%) −0.01 (−1%) 0 (0%) 10 −0.02 (−3%) −0.01 (−1%) −0.01 (−1%) 0 (0%) −0.02 (−2%) −0.01 (−1%) 50 −0.07 (−11%) −0.03 (−5%) −0.07 (−10%) −0.02 (−3%) −0.09 (−11%) −0.04 (−5%) 80 −0.14 (−27%) −0.06 (−12%) −0.15 (−25%) −0.06 (−10%) −0.17 (−27%) −0.07 (−11%) 90 −0.16 (−35%) −0.06 (−13%) −0.2 (−37%) −0.09 (−17%) −0.2 (−37%) −0.09 (−17%) 95 −0.17 (−40%) −0.08 (−19%) −0.21 (−43%) −0.1 (−20%) −0.22 (−44%) −0.11 (−22%) 98 −0.19 (−49%) −0.09 (−23%) −0.24 (−53%) −0.11 (−24%) −0.24 (−53%) −0.11 (−24%) The table above shows the difference in water velocity between different abstraction scenarios at AP1, keeping the structure settings constant

Table 5.2.2c Difference between structure scenarios for flow discharges (Ml/d) at AP 1

NB For each pair of columns, the abstraction scenarios have been kept the same to allow the difference of the structure settings to be identified. The percentage change is indicated in brackets. Fully licensed Historic Naturalised Difference Difference Difference Difference Difference between between between between Difference between Partially V- Closed and Partially Open Closed and Partially Open between Closed Open and Fully Percentile Fully Open and Fully Open Fully Open and Fully Open and Fully Open Open 5 −0.27 (−26%) −0.21 (−20%) −0.27 (−26%) −0.21 (−20%) −0.27 (−26%) −0.21 (−20%) 10 −0.27 (−27%) −0.2 (−20%) −0.27 (−26%) −0.2 (−20%) −0.27 (−26%) −0.21 (−20%) 50 −0.16 (−22%) −0.09 (−12%) −0.17 (−22%) −0.09 (−12%) −0.18 (−22%) −0.11 (−13%) 80 −0.07 (−16%) 0 (0%) −0.09 (−16%) −0.01 (−2%) −0.1 (−16%) −0.02 (−3%) 90 −0.04 (−12%) 0 (0%) −0.05 (−11%) 0 (0%) −0.08 (−15%) 0 (0%) 95 −0.03 (−11%) 0 (0%) −0.05 (−13%) 0 (0%) −0.08 (−16%) −0.01 (−2%) 98 −0.01 (−5%) 0 (0%) −0.04 (−12%) 0 (0%) −0.06 (−13%) 0 (0%) The table above shows the difference in water velocity between different structure settings at AP1, keeping the abstraction scenario constant

Table 5.2.2d Flow velocities (m/s) at different exceedance values under the different scenarios for AP 2

Structures = closed Structures = partially open Structures = fully open V- Fully Fully Fully Percentile Historic Naturalised Historic Naturalised Historic Naturalised licensed licensed licensed 5 0.59 0.59 0.6 0.62 0.62 0.62 0.69 0.69 0.69 10 0.57 0.58 0.58 0.6 0.61 0.61 0.68 0.68 0.68 50 0.36 0.39 0.4 0.42 0.43 0.45 0.56 0.58 0.59 80 0.25 0.28 0.31 0.34 0.35 0.36 0.52 0.53 0.53 90 0.21 0.24 0.27 0.32 0.32 0.34 0.51 0.52 0.53 95 0.19 0.22 0.26 0.32 0.32 0.33 0.48 0.5 0.51 98 0.16 0.2 0.24 0.3 0.31 0.32 0.43 0.47 0.49 The table above shows the difference in water velocity for different structure settings, and different abstraction scenarios at AP2

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Table 5.2.2e Difference between abstraction scenarios for velocities (m/s) at AP 2

Difference Difference Difference Difference Difference Difference between V- between Full between between Full between between Full Licence & Percentile Licence & Historic & Licence & Historic & Historic & Naturalised Naturalised Naturalised Naturalised Naturalised Naturalised 5 −0.01 (−2%) −0.01 (−2%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 10 −0.01 (−2%) 0 (0%) −0.01 (−2%) 0 (0%) 0 (0%) 0 (0%) 50 −0.04 (−10%) −0.01 (−3%) −0.03 (−7%) −0.02 (−4%) −0.03 (−5%) −0.01 (−2%) 80 −0.06 (−19%) −0.03 (−10%) −0.02 (−6%) −0.01 (−3%) −0.01 (−2%) 0 (0%) 90 −0.06 (−22%) −0.03 (−11%) −0.02 (−6%) −0.02 (−6%) −0.02 (−4%) −0.01 (−2%) 95 −0.07 (−27%) −0.04 (−15%) −0.01 (−3%) −0.01 (−3%) −0.03 (−6%) −0.01 (−2%) 98 −0.08 (−33%) −0.04 (−17%) −0.02 (−6%) −0.01 (−3%) −0.06 (−12%) −0.02 (−4%) The table above shows the difference in water velocity between different abstraction scenarios at AP2, keeping the structure settings constant

Table 5.2.2f Difference between structure scenarios for flow discharges (Ml/d) at AP 2

NB For each pair of columns, the abstraction scenarios have been kept the same to allow the difference of the structure settings to be identified. The percentage change is indicated in brackets. Fully licensed Historic Naturalised Difference Difference Difference Difference Difference between between between between Difference between Q- between Closed Partially Open Closed and Partially Open Closed and Partially Open and Percentile and Fully Open and Fully Open Fully Open and Fully Open Fully Open Fully Open 5 −0.1 (−14%) −0.07 (−10%) −0.1 (−14%) −0.07 (−10%) −0.09 (−13%) −0.07 (−10%) 10 −0.11 (−16%) −0.08 (−12%) −0.1 (−15%) −0.07 (−10%) −0.1 (−15%) −0.07 (−10%) 50 −0.2 (−36%) −0.14 (−25%) −0.19 (−33%) −0.15 (−26%) −0.19 (−32%) −0.14 (−24%) 80 −0.27 (−52%) −0.18 (−35%) −0.25 (−47%) −0.18 (−34%) −0.22 (−42%) −0.17 (−32%) 90 −0.3 (−59%) −0.19 (−37%) −0.28 (−54%) −0.2 (−38%) −0.26 (−49%) −0.19 (−36%) 95 −0.29 (−60%) −0.16 (−33%) −0.28 (−56%) −0.18 (−36%) −0.25 (−49%) −0.18 (−35%) 98 −0.27 (−63%) −0.13 (−30%) −0.27 (−57%) −0.16 (−34%) −0.25 (−51%) −0.17 (−35%) The table above shows the difference in water velocity between different structure settings at AP2, keeping the abstraction scenario constant

Table 5.2.2g Flow velocities (m/s) at different exceedance values under the different scenarios for AP 4

Structures = closed Structures = partially open Structures = fully open V- Fully Fully Fully Percentile Historic Naturalised Historic Naturalised Historic Naturalised licensed licensed licensed 5 0.36 0.37 0.37 0.38 0.39 0.39 0.47 0.47 0.47 10 0.33 0.33 0.33 0.35 0.36 0.36 0.47 0.47 0.47 50 0.24 0.25 0.26 0.27 0.29 0.30 0.35 0.37 0.39 80 0.15 0.18 0.20 0.18 0.21 0.23 0.25 0.27 0.30 90 0.12 0.15 0.17 0.17 0.18 0.20 0.21 0.24 0.27 95 0.11 0.14 0.16 0.16 0.17 0.19 0.19 0.23 0.25 98 0.09 0.12 0.15 0.15 0.17 0.18 0.17 0.21 0.24 The table above shows the difference in water velocity for different structure settings, and different abstraction scenarios at AP4

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Table 5.2.2h Difference between abstraction scenarios for velocities (m/s) at AP 4

Difference Difference Difference Difference Difference between Difference V- between Full between between Full between Full Licence & between Historic Percentile Licence & Historic & Licence & Historic & Naturalised & Naturalised Naturalised Naturalised Naturalised Naturalised 5 −0.01 (−3%) 0 (0%) −0.01 (−3%) 0 (0%) 0 (0%) 0 (0%) 10 0 (0%) 0 (0%) −0.01 (−3%) 0 (0%) 0 (0%) 0 (0%) 50 −0.02 (−8%) −0.01 (−4%) −0.03 (−12%) −0.01 (−3%) −0.04 (−10%) −0.02 (−5%) 80 −0.05 (−25%) −0.02 (−10%) −0.05 (−25%) −0.02 (−9%) −0.05 (−17%) −0.03 (−10%) 90 −0.05 (−29%) −0.02 (−12%) −0.03 (−18%) −0.02 (−10%) −0.06 (−22%) −0.03 (−11%) 95 −0.05 (−31%) −0.02 (−13%) −0.03 (−19%) −0.02 (−11%) −0.06 (−24%) −0.02 (−8%) 98 −0.06 (−40%) −0.03 (−20%) −0.03 (−20%) −0.01 (−6%) −0.07 (−29%) −0.03 (−13%) The table above shows the difference in water velocity between different abstraction scenarios at AP4, keeping the structure settings constant

Table 5.2.2i Difference between structure scenarios for flow discharges (Ml/d) at AP 4

NB For each pair of columns, the abstraction scenarios have been kept the same to allow the difference of the structure settings to be identified. The percentage change is indicated in brackets. Fully licensed Historic Naturalised Difference Difference Difference Difference between between between Difference Difference between Q- between Closed Partially Open Closed and Partially Open between Closed Partially Open and Percentile and Fully Open and Fully Open Fully Open and Fully Open and Fully Open Fully Open 5 −0.11 (−23%) −0.09 (−19%) −0.1 (−21%) −0.08 (−17%) −0.1 (−21%) −0.08 (−17%) 10 −0.14 (−30%) −0.12 (−26%) −0.14 (−30%) −0.11 (−23%) −0.14 (−30%) −0.11 (−23%) 50 −0.11 (−31%) −0.08 (−23%) −0.12 (−32%) −0.08 (−22%) −0.13 (−33%) −0.09 (−23%) 80 −0.1 (−40%) −0.07 (−28%) −0.09 (−33%) −0.06 (−22%) −0.1 (−33%) −0.07 (−23%) 90 −0.09 (−43%) −0.04 (−19%) −0.09 (−38%) −0.06 (−25%) −0.1 (−37%) −0.07 (−26%) 95 −0.08 (−42%) −0.03 (−16%) −0.09 (−39%) −0.06 (−26%) −0.09 (−36%) −0.06 (−24%) 98 −0.08 (−47%) −0.02 (−12%) −0.09 (−43%) −0.04 (−19%) −0.09 (−38%) −0.06 (−25%) The table above shows the difference in water velocity between different structure settings at AP4, keeping the abstraction scenario constant

5.2.3. Effects upon water levels

Tables 5.2.3a–i and Figures 5.2.3a–c present the results of the hydraulic model for water level under the different scenarios for Assessment Points 1, 2 and 4 over the 15-year study period. As discussed in Section 5.2.1, these tables and figures show the results from all possible combinations of the two key factors: abstraction and structure settings and so careful interpretation is needed, so the results pertaining to naturalised conditions will be examined first, and then the effect of abstraction. Thus Figures 5.2.3d–i present the difference between the structure settings with naturalised abstraction (i.e. none) with regard to water levels for 2006 and 2007, in order to highlight the magnitude and spatial extent of the structures and tidal regime over the representative dry and wet years. Figures 5.2.2j–q present the difference between the abstraction scenarios with regard to water levels for 2006 and 2007, in order to highlight the magnitude and spatial extent of the abstraction. Finally Figures 5.2.2r to s show a combination of abstraction and structure settings to show the worst case scenario. The tables are grouped into a set of three (a, b, and c) for each assessment point: a–c for AP1; d–f for AP2 and g–i for AP4. The first table presents water level statistics for different structure settings, and different abstraction scenarios at AP1; the second table shows the difference between different abstraction scenarios,

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Table 5.2.3a Water levels (m) at different exceedance values under the different scenarios for AP 1

Structures = closed Structures = partially open Structures = fully open WL- Fully Fully Fully Percentile Historic Naturalised Historic Naturalised Historic Naturalised licensed licensed licensed 5 3.16 3.18 3.20 3.13 3.16 3.18 3.08 3.11 3.12 10 2.99 3.02 3.03 2.96 2.99 3.00 2.88 2.92 2.94 50 2.50 2.55 2.59 2.41 2.47 2.51 2.31 2.35 2.38 80 2.27 2.34 2.38 2.18 2.22 2.27 2.18 2.22 2.25 90 2.20 2.27 2.32 2.13 2.18 2.21 2.13 2.18 2.21 95 2.17 2.23 2.29 2.11 2.15 2.20 2.11 2.15 2.19 98 2.12 2.20 2.26 2.08 2.13 2.17 2.08 2.13 2.17

The table above shows the difference in water level for different structure settings, and different abstraction scenarios at AP1

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Table 5.2.3b Difference between abstraction scenarios for water levels (m/s) at AP 1

Difference Difference Difference Difference Difference Difference between WL- between Full between Full between between Historic between Historic Full Licence & Percentile Licence & Licence & Historic & & Naturalised & Naturalised Naturalised Naturalised Naturalised Naturalised 5 −0.04 (−1%) −0.02 (−1%) −0.05 (−2%) −0.02 (−1%) −0.04 (−1%) −0.01 (0%) 10 −0.04 (−1%) −0.01 (0%) −0.04 (−1%) −0.01 (0%) −0.06 (−2%) −0.02 (−1%) 50 −0.09 (−3%) −0.04 (−2%) −0.1 (−4%) −0.04 (−2%) −0.07 (−3%) −0.03 (−1%) 80 −0.11 (−5%) −0.04 (−2%) −0.09 (−4%) −0.05 (−2%) −0.07 (−3%) −0.03 (−1%) 90 −0.12 (−5%) −0.05 (−2%) −0.08 (−4%) −0.03 (−1%) −0.08 (−4%) −0.03 (−1%) 95 −0.12 (−5%) −0.06 (−3%) −0.09 (−4%) −0.05 (−2%) −0.08 (−4%) −0.04 (−2%) 98 −0.14 (−6%) −0.06 (−3%) −0.09 (−4%) −0.04 (−2%) −0.09 (−4%) −0.04 (−2%) The table above shows the difference in water level between different abstraction scenarios at AP1, keeping the structure settings constant

Table 5.2.3c Difference between structure scenarios for water levels (Ml/d) at AP 1

NB For each pair of columns, the abstraction scenarios have been kept the same to allow the difference of the structure settings to be identified. The percentage change is indicated in brackets. Fully licensed Historic Naturalised Difference Difference Difference Difference between Difference between Difference between between Partially between Partially between Partially Q- Closed and Open and Closed and Open and Closed and Open and Percentile Fully Open Fully Open Fully Open Fully Open Fully Open Fully Open 5 0.08 (3%) 0.05 (2%) 0.07 (2%) 0.05 (2%) 0.08 (3%) 0.06 (2%) 10 0.11 (4%) 0.08 (3%) 0.1 (3%) 0.07 (2%) 0.09 (3%) 0.06 (2%) 50 0.19 (8%) 0.1 (4%) 0.2 (9%) 0.12 (5%) 0.21 (9%) 0.13 (5%) 80 0.09 (4%) 0 (0%) 0.12 (5%) 0 (0%) 0.13 (6%) 0.02 (1%) 90 0.07 (3%) 0 (0%) 0.09 (4%) 0 (0%) 0.11 (5%) 0 (0%) 95 0.06 (3%) 0 (0%) 0.08 (4%) 0 (0%) 0.1 (5%) 0.01 (0%) 98 0.04 (2%) 0 (0%) 0.07 (3%) 0 (0%) 0.09 (4%) 0 (0%) The table above shows the difference in water level between different structure settings at AP1, keeping the abstraction scenario constant

Table 5.2.3d Water levels (m) at different exceedance values under the different scenarios for AP 2

Structures = closed Structures = partially open Structures = fully open WL- Fully Fully Fully Percentile Historic Naturalised Historic Naturalised Historic Naturalised licensed licensed licensed

5 3.07 3.1 3.11 3.04 3.07 3.08 2.98 3 3.02 10 2.91 2.94 2.96 2.88 2.9 2.92 2.79 2.82 2.84 50 2.47 2.51 2.55 2.36 2.41 2.45 2.11 2.17 2.22 80 2.25 2.31 2.35 2.06 2.16 2.22 1.79 1.88 1.95 90 2.18 2.25 2.3 1.87 2.04 2.13 1.68 1.77 1.85 95 2.15 2.21 2.27 1.75 1.97 2.09 1.63 1.72 1.8 98 2.11 2.18 2.24 1.61 1.84 2.03 1.57 1.67 1.76 The table above shows the difference in water level for different structure settings, and different abstraction scenarios at AP2

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Difference Difference Difference Difference Difference Difference WL- between Full between between Full between between Full between Percentile Licence & Historic & Licence & Historic & Licence & Historic & Naturalised Naturalised Naturalised Naturalised Naturalised Naturalised 5 −0.04 (−1%) −0.01 (0%) −0.04 (−1%) −0.01 (0%) −0.04 (−1%) −0.02 (−1%) 10 −0.05 (−2%) −0.02 (−1%) −0.04 (−1%) −0.02 (−1%) −0.05 (−2%) −0.02 (−1%) 50 −0.08 (−3%) −0.04 (−2%) −0.09 (−4%) −0.04 (−2%) −0.11 (−5%) −0.05 (−2%) 80 −0.1 (−4%) −0.04 (−2%) −0.16 (−7%) −0.06 (−3%) −0.16 (−8%) −0.07 (−4%) 90 −0.12 (−5%) −0.05 (−2%) −0.26 (−12%) −0.09 (−4%) −0.17 (−9%) −0.08 (−4%) 95 −0.12 (−5%) −0.06 (−3%) −0.34 (−16%) −0.12 (−6%) −0.17 (−9%) −0.08 (−4%) 98 −0.13 (−6%) −0.06 (−3%) −0.42 (−21%) −0.19 (−9%) −0.19 (−11%) −0.09 (−5%) The table above shows the difference in water level between different abstraction scenarios at AP2, keeping the structure settings constant

Table 5.2.3f Difference between structure scenarios for water levels (Ml/d) at AP 2

NB For each pair of columns, the abstraction scenarios have been kept the same to allow the difference of the structure settings to be identified. The percentage change is indicated in brackets. Fully licensed Historic Naturalised Difference Difference Difference Difference between Difference between Difference between between Partially between Partially between Partially Q- Closed and Open and Closed and Open and Closed and Open and Percentile Fully Open Fully Open Fully Open Fully Open Fully Open Fully Open 5 0.09 (3%) 0.06 (2%) 0.1 (3%) 0.07 (2%) 0.09 (3%) 0.06 (2%) 10 0.12 (4%) 0.09 (3%) 0.12 (4%) 0.08 (3%) 0.12 (4%) 0.08 (3%) 50 0.36 (17%) 0.25 (12%) 0.34 (16%) 0.24 (11%) 0.33 (15%) 0.23 (10%) 80 0.46 (26%) 0.27 (15%) 0.43 (23%) 0.28 (15%) 0.4 (21%) 0.27 (14%) 90 0.5 (30%) 0.19 (11%) 0.48 (27%) 0.27 (15%) 0.45 (24%) 0.28 (15%) 95 0.52 (32%) 0.12 (7%) 0.49 (28%) 0.25 (15%) 0.47 (26%) 0.29 (16%) 98 0.54 (34%) 0.04 (3%) 0.51 (31%) 0.17 (10%) 0.48 (27%) 0.27 (15%) The table above shows the difference in water level between different structure settings at A24, keeping the abstraction scenario constant

Table 5.2.3g Water levels (m) at different exceedance values under the different scenarios for AP4

Structures = closed Structures = partially open Structures = fully open WL- Fully Fully Fully Percentile Historic Naturalised Historic Naturalised Historic Naturalised licensed licensed licensed 5 2.95 2.97 2.98 2.91 2.93 2.94 2.82 2.84 2.85 10 2.82 2.84 2.85 2.77 2.80 2.81 2.65 2.68 2.70 50 2.43 2.47 2.50 2.31 2.36 2.40 2.01 2.07 2.10 80 2.23 2.29 2.33 2.03 2.12 2.18 1.69 1.78 1.85 90 2.17 2.23 2.27 1.83 2.01 2.10 1.57 1.67 1.75 95 2.14 2.20 2.25 1.70 1.94 2.05 1.51 1.62 1.71 98 2.10 2.17 2.22 1.52 1.81 2.00 1.45 1.56 1.65

The table above shows the difference in water level for different structure settings, and different abstraction scenarios at AP4

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Difference Difference Difference Difference Difference Difference WL- between Full between between Full between between Full between Percentile Licence & Historic & Licence & Historic & Licence & Historic & Naturalised Naturalised Naturalised Naturalised Naturalised Naturalised 5 −0.03 (−1%) −0.01 (0%) −0.03 (−1%) −0.01 (0%) −0.03 (−1%) −0.01 (0%) 10 −0.03 (−1%) −0.01 (0%) −0.04 (−1%) −0.01 (0%) −0.05 (−2%) −0.02 (−1%) 50 −0.07 (−3%) −0.03 (−1%) −0.09 (−4%) −0.04 (−2%) −0.09 (−4%) −0.03 (−1%) 80 −0.1 (−4%) −0.04 (−2%) −0.15 (−7%) −0.06 (−3%) −0.16 (−9%) −0.07 (−4%) 90 −0.1 (−4%) −0.04 (−2%) −0.27 (−13%) −0.09 (−4%) −0.18 (−10%) −0.08 (−5%) 95 −0.11 (−5%) −0.05 (−2%) −0.35 (−17%) −0.11 (−5%) −0.2 (−12%) −0.09 (−5%) 98 −0.12 (−5%) −0.05 (−2%) −0.48 (−24%) −0.19 (−10%) −0.2 (−12%) −0.09 (−5%) The table above shows the difference in water level between different abstraction scenarios at AP4, keeping the structure settings constant

Table 5.2.3i Difference between structure scenarios for water levels (Ml/d) at AP 4

NB For each pair of columns, the abstraction scenarios have been kept the same to allow the difference of the structure settings to be identified. The percentage change is indicated in brackets. Fully licensed Historic Naturalised Difference Difference Difference Difference Difference Difference between between between Partially between between Q- between Closed Partially Open and Closed and Open and Fully Closed and Partially Open Percentile and Fully Open Fully Open Fully Open Open Fully Open and Fully Open 5 0.13 (5%) 0.09 (3%) 0.13 (5%) 0.09 (3%) 0.13 (5%) 0.09 (3%) 10 0.17 (6%) 0.12 (5%) 0.16 (6%) 0.12 (4%) 0.15 (6%) 0.11 (4%) 50 0.42 (21%) 0.3 (15%) 0.4 (19%) 0.29 (14%) 0.4 (19%) 0.3 (14%) 80 0.54 (32%) 0.34 (20%) 0.51 (29%) 0.34 (19%) 0.48 (26%) 0.33 (18%) 90 0.6 (38%) 0.26 (17%) 0.56 (34%) 0.34 (20%) 0.52 (30%) 0.35 (20%) 95 0.63 (42%) 0.19 (13%) 0.58 (36%) 0.32 (20%) 0.54 (32%) 0.34 (20%) 98 0.65 (45%) 0.07 (5%) 0.61 (39%) 0.25 (16%) 0.57 (35%) 0.35 (21%) The table above shows the difference in water level between different structure settings at AP4, keeping the abstraction scenario constant

5.3. Conclusions

5.3.1. Effects upon flows

The volumes taken by the Testwood PWS abstraction has been discussed in Section 1.5.2, and the hydraulic model has been used to assess the effect down the study reach in Section 5.2.1. In summary, it is difficult to disentangle the effects of the key influences upon the hydrological regime upon flows in the study reach. The use of the hydraulic model is presented in detail in Section 5.2.1 which examines the effect of each key influence with illustrative figures and tables. The key points however are that:  The greatest effect of the tidal regime is to cause water to back-up along the study reach (shown on the charts as a positive difference in flow), with considerable difference experienced at AP2 and AP4, and less at AP1;

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5.3.2. Effect upon velocities

The hydraulic model shows the progressive downstream reduction of channel velocities in the Lower Test due to (1) the impounding effect of the sluices at Testwood Mill and (2) tidal influences on the flow of water through the structures, especially during high spring tides. The use of the hydraulic model is presented in detail in Section 5.2.2 which examines the effect of each key influence with illustrative figures and tables; below is a summary of the findings. The observed velocity trends show a hydrological response more similar of a canal than a free-flowing river. Both the absolute velocities and the range of velocities recorded during the 16 year model simulation period are lowest close to the impounding sluices at AP4 (range of 0.10–0.35 m/s) and highest at AP1 (range of 0.20–0.80 m/s), downstream of the abstraction and 1.75 km upstream of the Testwood Mill structures. It is worth noting that throughout the simulation period, flow velocities at AP1 and 2 were above the threshold of 0.2 m/s that is typically used as the minimum velocity to sustain characteristic flora of chalk streams and rivers. The exception to this is the scenario of fully licensed flows with closed structures at AP2, which dip this threshold from V85–100); further, at AP4 many velocity scenarios dip below this threshold from V65 onwards, including naturalised flows with closed structures. In summary, the net effect of increased abstraction will be a reduction in river velocities during low flows, as expressed by the V95. The V95 describes both the magnitude and duration of effects under „low flow‟ conditions and is a metric that is typically used to characterise changes in velocities, flows or water levels as part of abstraction impact studies such as those done during the Habitats Directive process. The spatial extent of the abstraction effect extends between the abstraction point and the Testwood Mill structures although there is a significant downstream reduction in the effects of abstraction as other factors become a more dominant influence on in-channel velocities such as the impounding effects of historic water management structures or the tidal regime. Tidal water level variations and sluice operation have a significant effect on in-stream velocities in the Lower Test. In these cases, the effects are largest downstream at AP4 (close to Testwood Mill ) and smallest adjacent to the abstraction at AP1. Under current (historic) conditions at AP4 close to Testwood Mill, changing the sluice setting from partially open to fully open increases velocities by 0.06 m/s or 35% of the historic V95 at this location.

5.3.3. Effect upon water levels

During the NEP Investigation water level data has been collected from Environment Agency gauges and also temporary recording devices. The results (see Section 5.1) confirm that the hydrological behaviour of the Lower Test is more akin to that of a canal or impounded lake than a free-flowing river, and also show that the effect of the tidal regime extends upstream the Testwood gauging station. Throughout the monitoring period, water levels in the River Test remained above tidal levels, even during extreme surge events indicating that the tidal influence upon the river is indirect, i.e. it reduces or halts the passage of water through the Testwood Mill sluices (tide locking). Water levels at Testwood Gauging Station show a distinct response to tidal water level fluctuations; up to 0.15 m on the peak of spring tides. Monitoring of water levels in Testwood Pool mirrored tidal water level variations, with twice-daily water level variations of up to 0.25 m during neap tide periods and 1.25 m during spring tide periods. Water levels recorded upstream of Structure 1417 showed replicate water level variations to those recorded at Testwood Mill located 0.5 km downstream with variations of up to 0.25 m

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6.1. Introduction

The Environment Agency (EA) has provided an initial assessment of the aquatic species and habitats of the Lower Test area in its report Testwood Public Water Supply Abstraction Impact Investigation – Statement of Issues and Assessment (March 2010). Following discussion and review of the available data and reports with the EA, and submission of a Scoping Report to the EA in June 2011, it was agreed that the primary focus of the fisheries assessment in the NEP investigation would be on the salmon population. Salmon are considered to be the most sensitive of the fish species present in the Lower River Test and the EA has indicated that if the habitat and flow regime is generally acceptable for salmon it is likely to be acceptable for the other fish species present. If the effects of the Testwood abstraction on the salmon population are considered to be significant, however, further assessment of the potential effects on other species may also be required. In particular, if the temperature regime in the Lower Test is likely to be altered in any substantive way by the abstraction regime at Testwood, further consideration of the potential effects on sea trout would be required (see Table 1.2.1). This chapter sets out the work undertaken for the fish assessment part of the NEP and the key conclusions of the investigation.

6.1.1. Objectives of the NEP Investigation

In view of the EA review outlined above, and with regard to the long-term protection of the salmon population, the EA identified four “environmental objectives” against which the effect of the Testwood abstraction licence should be assessed. These are: 1. A flow regime in the lower River Test that maintains or improves passage for migrating salmon; 2. The effective screening of all abstraction intakes to prevent fish being drawn in and trapped at any stage of their life cycle; 3. The maintenance of a water temperature profile in the lower River Test which is not raised as a result of increased abstraction and is as resilient as possible to climate change; and 4. A flow regime that maintains or improves water quality in the River Test for salmonid populations. These objectives have therefore been used to shape the Scope of Work undertaken in the NEP investigation and this is summarised below.

6.1.2. Scope of Work

The scope of work covered by the investigation is outlined below under the four environmental objectives identified by the EA.

6.1.2.1. Environmental Objective 1: A flow regime in the lower River Test that maintains or improves passage for migrating salmon A significant proportion of the overall scope of work is focused on addressing this objective. Key elements are as follows:  A summary of the most relevant outcomes from Section 5, which reported on the assessment of the flow regime of the Great Test downstream of the Testwood abstraction;

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6.1.2.2. Environmental Objective 2: The effective screening of all abstraction intakes to prevent fish being drawn in and trapped at any stage of their life cycle Southern Water is funded in its “AMP5 Business Plan” (2010–2015) to undertake a major upgrade and refurbishment of the Testwood Water Treatment Works. This will include works to ensure that the abstraction intakes are screened in a manner that complies with the latest EA guidelines. As such, steps are already in place to comply with this objective and no additional work is proposed as part of the NEP investigation.

6.1.2.3. Environmental Objective 3: The maintenance of a water temperature profile in the lower River Test which is not raised as a result of increased abstraction and is as resilient as possible to climate change Key elements of work undertaken are as follows:  A review of the relationship(s) between historic water temperature and the available indices (e.g. salmon counter data; rod catch data) of the numbers and timing of salmon moving upstream beyond the Testwood abstraction intake.  An assessment of the relationship between water temperature and the flow regime (river flows, water velocities and depths) in the reaches downstream of the Testwood abstraction. This has necessitated the development of a thermal model of the Lower Test, which in turn draws on hydraulic model of the same sections.  Consideration of the potential in-combination effects of low flows and high temperatures on salmon movement in the reaches downstream of the Testwood abstraction.  Evaluation of the potential effect of abstraction on the resilience of the temperature regime to climate change. Findings against this objective are summarised in Sections 6.3 to 6.7.

6.1.2.4. Environmental Objective 4: A flow regime that maintains or improves water quality in the River Test for salmonid populations With regard to water quality, the EA scoping work for this NEP investigation made it clear that the principal water quality risk to the River Test salmonid populations arises from high sediment loads and siltation of spawning gravels. The EA indicated that the Testwood abstraction is not considered to be a major contributor to this problem and that this need not be a focus of the NEP investigation. Even so, outputs and conclusions arising from the hydraulic modelling work will have due regard for any implications for water quality. At this stage, however, there are no substantive developments to report.

6.1.2.5. Potential effects of abstracting the full licence at Testwood The assessments above focus primarily on understanding the degree to which the historic abstraction regime at Testwood has affected the achievement of the EA‟s environmental objectives for the Lower Test. In Section 6.3, consideration is given to the difference in the effect of abstraction that may arise were Southern Water to use the full licensed abstraction on a permanent basis at Testwood rather than continue at the historic levels, which are generally well below the full licensed quantities. Although this is a somewhat artificial scenario since such an abstraction regime is unlikely, it is necessary to evaluate the “risk profile” associated with the current licence.

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The EA has spent considerable time identifying the various data and reports available and relevant to the Lower Test area, and in particular those datasets that were potentially relevant to investigations of the Testwood abstraction. It is therefore not our intent to detail all the available individual datasets or repeat the work already documented: this section is a brief review of the sources of data used in the fisheries assessment including an assessment of the data limitations. The key sources of relevant data for the NEP assessment are as follows, and Figure 6.1.1 shows the key monitoring points and locations of interest (e.g. locations of fisheries):  The EA and its predecessor bodies has provided much data of various quality and quantity extend back over several decades;  Southern Water has provided abstraction data; and  The fisheries on the River Test have well kept rod catch records dating as far back as the 19th Century. The raw datasets that have been used in this assessment are listed in Table 6.2.1 and the derived datasets used in the fish assessment are as shown in Table 6.2.2.

Table 6.2.1 Raw data used in the fisheries assessment Dataset Source of Data Date Range Description / Issues HYDROLOGICAL DATA Daily mean flows from EA‟s Electromagnetic Environment 1982 to River Little Test at Conagar gauging station at Conagar Bridge on the Little Agency present River Test. Environment 1957 to Daily mean flows from EA‟s Chart Recorder on River Test at Broadlands Agency present the River Test at Broadlands Environment 1976 to River Cadnam at Ower Daily mean flows from the weir at Ower Agency present Environment 1996 to Daily mean flows from gauging station at River Great Test at Testwood Agency present Testwood Environment Tidal Data Tidal elevation data from Eling Mill tide gauge Agency Environment Actual measurements were taken with an Channel Cross Sections 2011 Agency Acoustic Doppler Current Profiler (ADCP) FISHERIES RELATED DATA Records of fish caught in the Mudeford catch Environment Mudeford Net Catch Data 2000–2007 (Christchurch Harbour) including fish weight, sea Agency age and date caught. Counts of salmon moving on the Great Test at Nursling Fish Counter Data Environment 1996–2009 Nursling fish counter (salmon only, upstream (Great Test) Agency movements). See Appendix 6.1 for further detail. Counts of salmon moving on the Little River Test Environment Little River Fish Counter Data 1997–2008 at Conagar (salmon only, upstream movements). Agency See Appendix 6.1 for further detail. Fisheries Nursling (from T&I), Testwood Rod catch records transcribed from Fishery Salmon Rod Catch Records 1937–2011 (from T&I) and records Derived Broadlands. Environment Periodic suspended solids analysis for the River Suspended Solids 1978–2007 Agency Test at Greatbridge. HYDRAULIC STRUCTURE DATA Environment EA design drawings for hydraulic structures at Hydraulic Structures n/a Agency Testwood Pool METEOROLOGICAL DATA Temperature, rainfall and sunshine hours Met Office (open Long Term Weather Records 2000–2010 averages from Hurn Airport (now called source data) Bournemouth International Airport) weather

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Table 6.2.1 Calculated datasets for inclusion within the assessment Dataset Description / Issues As no direct continuous flow gauging is done on the Great Test downstream of the confluence with Lower Test the River Blackwater, a dataset has been derived from existing data to represent the Testwood (Testwood Pool) Pool area (or basically anything downstream of the Blackwater confluence and upstream of the tidal Derived Flow limit), see Section 3.5, which represents the “Actual Residual Flow” (ARF) dataset. Southern Water Datasets abstraction data for Testwood is then removed from the ARF to give a “Naturalised Residual Flow” dataset for this area, see Section 1.6.2. Summary Salmon Data Summary records of: yearly rod catch totals (from rod licence returns), estimated returning stock from the (based on verified salmon counts from fish counters and catch records from downstream of counter Environment position), estimated spawning escapement values, and egg production estimates Agency Data obtained from surveys undertaken for the NEP, and scaled and un-scaled drawings of Structure Data structures in the Lower Test area Derived data from InfoWorks Derived cross section data and derived flow data from the InfoWorks hydraulic model hydraulic model Generated Tidal Tidal series derived using the Simplified Admiralty method Data River River centrelines derived from Google earth and corrected to appropriate Ordnance Survey Centrelines coordinate system Tree cover Approximate extent and size of bankside shading (trees) derived using Google Earth

6.2.1. Flow Data

Measuring flows in the Lower Test is complex due to the braded nature of the river in the floodplain and the consequent number of gauging stations installed over the years with lengths of record which vary in duration and quality. Considerable time was therefore taken to agree a flow series for the Great Test at the MRF location with the EA; this process is described in Section 3.5.1.

6.2.2. Abstraction at Testwood

Full details of the Testwood abstraction licence, the assessment of its historic use and the potential effect on flows in the lower reaches of the Great Test are outlined in Section 1.5.

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6.2.3.1. Rod Catch Data (1928–2006) The reported rod catches of the three main salmon fisheries on the River Test (Testwood, Nursling and Broadlands) are a useful measure of long-term changes in stock status, distribution of catches and seasonal timing of catches and runs. They are particularly important in extending back in time the analyses that are provided by the fish counter data, and daily catches at each of the three fisheries are available for the past 70 years in the form of estate record books. Total catches are summarised in Table 6.2.3 below.

Table 6.2.3 Total Rod Catch records for the River Test (Testwood + Nursling + Broadlands) 1928–2006 Year Rod Catch Year Rod Catch Year Rod Catch 1928 700 1955 948 1982 539 1929 292 1956 1126 1983 569 1930 255 1957 1005 1984 643 1931 373 1958 1424 1985 544 1932 1344 1959 1274 1986 722 1933 585 1960 1157 1987 478 1934 620 1961 833 1988 575 1935 1303 1962 1662 1989 475 1936 942 1963 1452 1990 285 1937 505 1964 1020 1991 127 1938 559 1965 965 1992 141 1939 877 1966 866 1993 308 1940 568 1967 758 1994 216 1941 726 1968 805 1995 163 1942 892 1969 1146 1996 138 1943 964 1970 969 1997 47 1944 728 1971 716 1998 204 1945 348 1972 930 1999 142 1946 292 1973 1129 2000 142 1947 222 1974 834 2001 209 1948 547 1975 1058 2002 336 1949 635 1976 620 2003 132 1950 642 1977 553 2004 449 1951 528 1978 437 2005 357 1952 790 1979 602 2006 210 1953 961 1980 838 1954 1511 1981 850

6.2.3.2. Fish Counter Data (1996–2010) Two fish counters have been in place on the River Test since the mid 1980s and are generally regarded as some of best examples in the U.K. One counter is located on the Great Test at Nursling Mill and the other located on the Little River Test upstream of Conagar. It is important to note that these counters are fish counters, not salmon-specific counters, and extracting salmon counts from overall fish count requires a degree of data processing, including analysis of wave forms recorded and verification using video stills. The data processing has been undertaken by the Environment Agency who has provided daily salmon upward movement counts for the period 1996–2010 (for the Great Test) and 1997–2008 (for the Little Test). The fish counter data are widely regarded as one of the best available in the UK. The operational principles of the fish counters, the means by which data are collected, checked and verified, and some of the uncertainties and potential limitations associated with the data are described in Appendix 6.1.

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Table 6.2.4 Annual Returning Stock Estimates and Residual Flow Q95 values

Adult Return ICES 2010 R. Lower Great Test Year Test RSE Residual Flow Q95 1988 1507 3.86 m3/s, 333.50 Ml/d) 1989 1730 1.95 m3/s, 168.48 Ml/d) 1990 790 1.81 m3/s, 156.38 Ml/d) 1991 538 3.12 m3/s, 269.57 Ml/d) 1992 488 2.95 m3/s, 254.88 Ml/d) 1993 920 4.01 m3/s, 346.46 Ml/d) 1994 618 4.43 m3/s, 382.75 Ml/d) 1995 517 2.96 m3/s, 255.74 Ml/d) 1996 515 3.08 m3/s, 266.11 Ml/d) 1997 317 3.19 m3/s, 275.62 Ml/d) 1998 748 3.86 m3/s, 333.50 Ml/d) 1999 777 4.54 m3/s, 392.26 Ml/d) 2000 537 5.34 m3/s, 461.38 Ml/d) 2001 408 5.24 m3/s, 452.74 Ml/d) 2002 1046 4.61 m3/s, 398.30 Ml/d) 2003 367 3.54 m3/s, 305.86 Ml/d) 2004 1129 4.24 m3/s, 366.34 Ml/d) 2005 1117 2.75 m3/s, 237.60 Ml/d) 2006 1058 2.67 m3/s, 230.67 Ml/d) 2007 664 6.71 m3/s, 579.74 Ml/d) 2008 1487 6.80 m3/s, 587.52 Ml/d) 2009 903 3.71 m3/s, 320.54 Ml/d) 2010 925 4.01 m3/s, 346.46 Ml/d)

6.3. The Flow Regime in the Great Test

As stated in Section 6.1.1, a key objective of the NEP assessment is to understand the risk that abstraction at Testwood poses to the passage of salmon up the Lower Test. A logical starting point in this context is to describe the nature of the “natural” flow regime in the Great Test and then address how this changes with abstraction at Testwood.

6.3.1. The “natural” flow regime (with zero abstraction at Testwood)

6.3.1.1. Upstream of the Testwood intake Figure 1.5.2 shows river flows for the period 1996–2011 at Testwood Gauging Station, which is located immediately downstream of the abstraction intake at Testwood.

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6.3.1.2. Downstream of the Testwood intake Downstream of the Testwood intake the nature of the flow regime undergoes a significant change. The reasons for this are as follows: 1. The River Blackwater joins the Great Test, returning water previously diverted via the Broadlands Fish Farm Carrier. The Blackwater is not a chalk river and has a much “flashier” flow regime with a higher sediment loading. This is particularly apparent following significant rainfall events, when a distinctive plume of sediment can be seen just downstream of the confluence of the two rivers. 2. The Testwood intake is located at, or slightly downstream of, the natural hydraulic limit of the tide and is therefore at the natural point of transition from normal fluvial flows to a tidally variant flow regime. As would normally be the case in a reach of this nature, the strength of the tidal influence increases as river flows reduce. 3. The impounding structures at Testwood Mill are just over 1.5 km downstream of the abstraction intake and are therefore well below the natural tidal limit. The structures were built to control the flow regime in the lower Great Test upstream of the Mill and they do this very effectively. Without the structures in place, water levels and velocities upstream of the Mill would oscillate with the tide. Depending on river flows and the stage of the spring-neap tidal cycle, this oscillation could extend up the Great Test as far as the Testwood intake and also up the lower reaches of the River Blackwater. The effect of the structures (with the sluice gates closed) is to hold back the river, significantly increasing upstream water levels above their natural levels and reducing water velocities below their natural levels. Figure 6.3.1 shows the simulated velocities and water levels at AP4, AP2 and AP1, which are approximately 0.25, 1.0 and 1.5 km upstream of Testwood Mill. AP1 is immediately downstream of the abstraction intake and upstream of the confluence with the River Blackwater; it does not benefit from the water returned to the river via the Blackwater and is therefore the reach with the lowest flows. The simulations in Figure 6.3.1 cover the period from January 2006 through to the end of December 2007 and show the seasonal variations in the flow regime in a very low flow year (2006) and a much higher flow

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6.3.1.3. Conditions for migrating salmon during low flows In summary, the nature of the flow regime in the Great Test downstream of the Testwood abstraction is highly dependent on the settings of the sluice gates on the structures at Testwood Mill. Thus, for any given flow in the Great Test downstream of the Testwood intake, a range of significantly different flow regimes are possible, particularly under lower flow conditions. Thus, the flow regime may vary between the following extremes:  With the gates open, or with no structures in place, the tidally variant flow regime observed downstream of the Mill would extend for much of the reach upstream to the confluence with the River Blackwater and the Testwood intake.  With the gates closed, the tidal influence would generally cease at Testwood Mill and the reach upstream would become much more stable, deeper and slow moving. It is important to note, however, that none of the flow regimes shown in Figure 6.3.1 are likely to provide any physical constraint to the migration of fish upstream. In other words, should a salmon or sea trout attempt to move upstream, the depths or velocities it would encounter would not prevent its progress.

6.3.2. The flow regime with continuous abstraction at Testwood of 136 Ml/d (the full licence)

Figure 6.3.2 compares the low flow regimes with zero abstraction (described above) with those that could occur under the worst-case abstraction scenario – continuous abstraction at a rate of 136 Ml/d. The figure focuses on the lowest flow period through the summer of 2006. The main observations of note are:  The conditions that a migrating fish might encounter under the two abstraction scenarios are generally very similar;  As might be expected, with the “gates open” simulation the tidal influence increases further upstream of Testwood Mill;  With the gates closed, there is a slight reduction in velocity and depth but the essential character of the reach as deep and slow moving remains the same;

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6.3.3. The flow regime at the Minimum Residual Flow (MRF)

Under the terms of the Testwood abstraction licence, regardless of the volume being abstracted flows must not reduce below the defined “Minimum Residual Flow” (MRF) as measured at a point downstream of the confluence with the River Blackwater (close to the location of AP2). The MRF is defined as 1.05 m3/s (91 Ml/d). Flows have never been recorded this low, but projections described elsewhere (see Section 3.5.1.1 and Appendix 3.5.1) suggest that in the two most extreme drought years in the last 100 years (1921 and 1976) flows could possibly have reached this low for a short period of time if Testwood had been operating at its full licensed quantity of 136 Ml/d. Figure 6.3.3 does not compare abstraction scenarios but simply examines what the flow regime might be like with a continuous flow in the lower Great Test of 1.05 m3/s. The scenario assumes that 0.5 m3/s is still being diverted to the River Blackwater via the Broadlands Fish Farm Carrier and so the flow at the MRF point is made up of 0.5 m3/s from the Great Test upstream (including at AP1) and 0.5 m3/s from the Blackwater. The usefulness of this scenario is not just to understand what the flow regime at the MRF might be like, but to understand how the flow regime might change below those low flows for which historic salmon counter data regarding are available (e.g. 2005 and 2006). What the graphs in Figure 6.3.3 indicate is that due to the combined effects of the tide and the impounding structures at Testwood Mill, the characteristics of the flow regime will remain broadly similar to those in less extreme years. Water depths remain at 0.5 m or above at all 3 locations and there are no apparent physical constraints to the movement of fish upstream.

6.3.4. Summary

One of the EA‟s main “Environmental Objectives” for the Lower Test is that the management of the flow regime should ensure that that the passage of migrating salmon is maintained or improved. With regard to the reach of the Great Test downstream of the Testwood abstraction intake, four factors potentially affect this objective at one or more points along this reach. They are: 1. The influence of the tidal cycle; 2. The presence and operation of the impounding structures at Testwood Mill; 3. The abstraction at Testwood; and 4. The management of control structures which allocate flows to the various channels in the Lower Test floodplain (of particular relevance to the Great Test is the diversion of flows to the Broadlands Fish Farm Carrier and to the Little Test).

The assessment outlined above suggests that at AP1, the biggest influences on the flow regime are factors 3 and 4 above. At AP2 and AP4, however, the biggest influences are factors 1 and 2. However, the assessment also suggests that none of the factors pose a significant risk to the EA‟s objective of ensuring that the flow regime maintains or improves the passage for migrating salmon. This conclusion will be tested further in the following sections as the data for salmon catches and movement are assessed and the implications for reduced flows on water temperatures are evaluated.

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6.4.1. Overview

Adult salmon enter the River Test to spawn. Spawning takes place throughout much of the main river between Broadlands and Longparish, and in the lower reaches of the Anton to about Goodworth Clatford. Spawning takes place in the winter (mainly December and January), but the fish enter the river many months before this, typically in recent years between May and August. Most fish spend much of the intervening period between river entry and spawning in the lower reaches (including the tidal reach), though a proportion penetrate further into the river, well beyond Romsey, within a week or two of river entry. Renewed upstream migration to the spawning grounds generally occurs in the autumn in response to increased river flow following heavy rainfall. The young fish typically spend a year (sometimes two years) in the river before migrating to sea as smolts in April and May. They return as adults after one or two years (rarely three or more) years. They return to the river of their birth so that the stocks in each river are genetically distinct, and have evolved life-history strategies and tactics according to the specific conditions prevailing within each river. Genetic studies have shown that the chalk-stream salmon stocks (Itchen, Test, Avon, Piddle and Frome) are broadly similar, but are sharply distinct from other UK stocks. Fish returning after one year are termed one sea-winter (1SW) fish or grilse. They typically return in July and August, and are generally 2–3 kg in weight. Two sea-winter (2SW) fish return between about April and August, peaking in June, and are typically 3–7 kg in weight. In the last 20–30 years these two age-classes comprise the overwhelming majority of adult salmon returning to the Test. Formerly, there were many 3SW fish returning in the spring (February–May) weighing of the order of 7–15 kg and a small number of 4SW fish weighing anything up to 20 kg or more. In the 1930s and 40s such fish comprised about 25% of the stock, but they started to decline as a percentage of the catch in the 1950s and today represent a negligible proportion. The proportion of the stock returning as 2 SW fish has also fallen so that grilse now comprise about three quarters of the rod catch (2006–2010 = 74.8%). The timing of the grilse run has also changed over the past 25 years, with August replacing July as the peak month for rod catches. These matters of run timing are important in the context of this investigation as they mean that much of the stock now returns to the river at times of highest temperatures and low river flow. Evidence from the Avon and other southern salmon rivers indicates that fish may be encouraged to remain in the lowermost reaches, including tidal areas, by low flows and/or high temperatures. It is possible that these fish may suffer disproportionate losses compared to fish entering the river promptly, thus emphasising the importance of ensuring that the flow regime in the lower river maintains or improved the passage for migrating salmon. In view of the review of the flow regime under various abstraction scenarios in Section 6.3 above, the major focal points of this section are as follows: i) Review of the historical rod catch data, in particular the distribution of fish caught during the angling season (ends on October 2nd) and what bearing the prevailing flow regime may have on this; ii) Review of the EA‟s annual “Returning Stock” data; iii) Review of the salmon counter data (1996–2010) and what can be learned in regard to the relationship between the patterns of salmon movement and the prevailing flow regimes on the Great and Little Test; iv) Use of the historic data and expert knowledge to construct a “conceptual model” of salmon movement on the Great Test.

6.4.1.1. Limitations of comparisons between annual stock data As part of the ongoing consultation with the EA in this investigation, the EA have stressed that a range of studies in recent years suggest that the numbers of fish that return to the river each year is determined by a range, with the primary factors being:

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6.4.2. Rod Catch data

A review of rod catch data in the Lower Test was undertaken by Dr David Solomon for the purposes of this investigation and this is summarised below. The locations of the three salmon fisheries on the Lower Test are shown in Figure 6.1.1 and the annual combined total rod catches are shown in Table 6.2.1.

6.4.2.1. Changes in the Annual Rod Catch The combined annual catches for the three fisheries are shown in Figure 6.4.1 (this shows the data in Table 6.2.1). The figures for 1994 onwards are for the whole river, and thus include a very small contribution from some minor fisheries in the Romsey area. It is clear that catches were burgeoning in the 1950s to 1960s, and then steadily fell to lows in the 1990s. There has been a limited recovery in total catch since then and in recent years the figures will have been influenced by the introduction of a catch and release policy which tends to boost overall rod catch relative to the total stock. Figure 6.4.2 shows two graphs: the annual Rod Catch totals plotted against the Q95 flow at Broadlands GS from 1960–2009 and the percentage of the annual rod catch that was caught at Broadlands, the furthest upstream of the Lower Test fisheries. Figure 6.4.3 shows the same data plotted against the mean daily maximum summer temperatures at Hurn Airport. The data have been colour-coded by decade and this clearly shows how the rod catch reduced significantly between the late 1950s and the 1980s before stabilising at much lower levels in the 1990s. This is consistent with the decline in the salmon population since the 1950s, a phenomenon which seems to be associated primarily with losses in the marine phase of the salmon life cycle (as discussed in section 6.4.4.1 above). In this regard, with the exception of the 1960s, which had several exceptionally wet years and no dry years, there does not appear to have been a significant change in the long-term average annual Q95 at Broadlands during this period (see Table 6.2.2 for a summary by decade) and there is also no clear relationship between the Q95 flow and the rod catch in each of the decades shown, despite the wide range of Q95 flows represented. With regard to temperature (Figure 6.4.3), however, a progressive increase in average summer temperatures is apparent (see Table 6.4.1) since the 1950s, with the post-1990 clusters shifting to the right along the temperature axis. This rise in temperature is consistent with the wider literature on climate change in the UK. There appears to be a distinct trend of decreasing rod catch in warmer years, although it is not statistically significant. The apparent trend may also be due to auto-correlation and may reflect the observation of many anglers that warm, sunny conditions are not generally conducive to salmon fishing. Although neither of the relationships shown are statistically significant (R2=0.13 and 0.31 for Q95 flow and temperature, respectively), there is some suggestion that in the warmest and lowest flow years in each decade a lower proportion of salmon make it up to the Broadlands fishery during the salmon fishing season (i.e. by the beginning of October). This may be due to local environmental factors (river or estuarine), reduced fishing effort or a change in the age class distribution of returning fish (see below) in these years.

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Table 6.4.1 Decade averaged Broadlands Q95 flows and summer maximum air temperatures Average Summer (April–Sept) Daily Average Annual Q95 at Time Period Maximum Air Temperature (DegC) at Broadlands GS Hurn Airport 1960–69 7.3 m3/s ( 630.72 Ml/d) 17.8 1970–79 6.3 m3/s (544.32 Ml/d) 18.1 1980–89 6.5 m3/s (561.6 Ml/d) 18.5 1990–99 6.0 m3/s (518.40 Ml/d) 19.1 2000–09 6.7 m3/s (578.88 Ml/d) 19.2

6.4.2.2. Changes in the timing of catches Over the years there have been some major changes in the seasonal distribution of rod catches of salmon on the Test. The seasonal breakdown since 1928 on the three main rod fisheries (Testwood, Nursling and Broadlands) is shown in Figure 6.4.4. This shifting pattern is due almost entirely to a change in the age-class structure of the population; as described earlier, each sea age class has a specific season of return to the river, and most fish which are caught succumb in the first week or two after they enter the river. Indeed, the seasonal breakdown limits shown in Figure 6.4.4 were specifically chosen to highlight the shift in age-class composition of the catch. The fish caught before May are predominantly 3 SW; those in May and June 2 SW, and July onwards mainly grilse (1 SW) with some 2 SW. The decline of multi sea-winter fish, especially 3SW, is a phenomenon recorded throughout the British Isles and is believed to be due to changes in marine conditions. An apparently separate phenomenon is a gradual shift to slightly later running (or at least later rod catch) of grilse. Although there is variation between years the median date of catch appears to have moved about 2 to 3 weeks later between the 1980s and recent years, such that the peak of catches has moved from July into August. This has also been noted on the Hampshire Avon.

6.4.2.3. Changes in the distribution of catches There has also been a major shift in the distribution of catches between the three main fisheries on the Lower Test (Figure 6.4.5). The proportion of catches in the lowermost fishery, Testwood, has risen from an average of 29% in the 1940s to 68% in recent years. In the same period, the proportional catch at Nursling has fallen from 60% to 25%. In the Broadlands fishery, which is the furthest upstream, the proportional catch rose from 11% in the 1940s to nearly 30% in the 1950s. It remained at this level until the 1980s, before falling back again to just under 10% in the last decade. Interestingly, the Broadlands catch in 2011 has been the best for many years, although it is not yet possible to know whether this constitutes a genuine sustained recovery in “upstream” catches.

This distribution of the catch between the beats is likely to reflect, at least in part, the distribution of the fish during the angling season. For example, data from the salmon counters since 1996 suggest that on average 65% of salmon move up the Great Test and 35% move up the Little Test. The equivalent catch data for the same period are 73% for Testwood (on the Great Test) and 27% for Nursling (Little Test) fisheries, suggesting that in this instance at least the catch data are a reasonable reflection of the numbers of fish present. Whilst the flow regime may be one factor in the reduced proportion of fish moving further upstream to Broadlands during the angling season, other possible contributory factors include:  Lower stock of fish overall, which means that the lowermost fisheries will do relatively better as the river tends to “fill-up” from the tidal limit upstream;  Changes in the sea-age-class distribution – observations on many rivers suggest that early-running fish will tend to migrate further before stopping; the decline in the proportion of early-running fish may therefore mean that a higher proportion of the returning stock will stop lower down the river;

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6.4.3. Returning Stock Estimates (RSE)

The RSE is an EA-derived estimate of the number of salmon that make it back into the river each year to spawn (following the full implementation of a catch and release policy, the RSE is equivalent to the estimated spawning escapement on the river). Although based primarily on the salmon counter data, in the years prior to the implementation of the full catch and release policy (pre-2000), it included those fish downstream of the fish counters that were caught but no released back to the river. For those years with significant counter downtime the RSE also draws heavily on rod catch data. Figure 6.4.6 plots the RSE data against the annual rod catch data for the period 1988–2009 and shows the close relationship between the two datasets. Figure 6.4.7 plots the Q95 flows at the MRF point on the Great Test against the RSE data for the period 1988–2010 (the two data sets were tabulated in Table 6.2.3). The RSE data show significant variation right across the low flow range encountered. The Figure also highlights the 5 warmest years, which between them cover the full range of RSE from the highest (1989) through to the second lowest (2003). Whilst the limitations of the annual data stated in Section 6.4.1.1 precludes any definitive conclusions regarding the processes underlying the variation in the annual RSE data, it is possible to state the following:  there is no correlation (R2=0.0005) between the annual RSE and river flows on the Great Test; put simply, very low flow years can equally be associated with high and low spawning escapement;  even if the annual spawning escapement is affected by the magnitude of flows or water temperatures, their influence is of much lower significance than the factors such as smolt migration and marine survival that are considered to be the key drivers behind the numbers of returning salmon (see Section 2.2.1 for the EA‟s summary of these factors).

6.4.4. Daily Fish Counter Data

Whilst taking account of the statements above regarding the potential significance of localised flow or temperature effects on overall spawning escapement, the salmon counter data allow a much more detailed evaluation of the relationship between salmon movement and river flows and the need to ensure that the passage of salmon up the Great Test is maintained or improved. The section uses the available daily fish counter data for the Great Test for the period 1996–2010 (excluding 2001 for which there is no counter data available and 2009 when there was significant downtime). The data have been processed, checked and issued by the EA. The counter data extend from May 1st to December

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6.4.4.1. How representative are river flows and temperatures in the 1996–2010 period? Based on the flow record at Broadlands GS, which starts in 1958, the 1996–2010 period includes 3 of the 4 lowest flow years in the last 50 years (1997, 2005 and 2006). The lowest flow year was 1976. A comparison of the flow hydrographs in 1976 and 2006 at Broadlands GS is shown in Figure 6.4.8. The hydrograph for 2007 (high summer flow) is also shown for comparative purposes. The hydrographs show that from mid June through July and August flows in 2006 closely matched those in the 1976 drought. Indeed, from early September and for the remainder of the autumn period flows were lower in 2006 than 1976. Based on the long-term temperature record at Hurn Airport, the summer of 2006 was also one of the warmest in Hampshire in the last 50 years, behind 1976 and 1995. Figure 6.4.3(a) also showed that summer temperatures in the last 20 years have generally been warmer than in the previous 30 years, with 6 of the 10 warmest years in the last 50 years occurring in the 1996–2010 period. With regard to the combined effects of low flows and warm summer temperatures, Figure 6.4.9 plots the annual Q95 flows at Broadlands GS against the mean summer daily maximum temperatures at Bournemouth Airport for the 50-year period from 1961 to 2010. The figure highlights the 8 most extreme years in terms of temperature and low flows and four of these are in the 1996–2010 period (1997, 2003, 2005 and 2006). The two most extreme years are 1976 and 2006. Overall, it is clear that the more extreme low flow periods and/or warm summers are very well represented in the study period.

6.4.4.2. Overview of the Data Figure 6.4.10 shows the full 14-year data set (as indicated above this excludes 2001 and 2009) for the upstream salmon movement detected at the Nursling Mill fish counter (located 0.5 km upstream of the Testwood abstraction). The data are plotted against flow at the MRF location on the day on which fish movement was recorded. The main observations from Figure 6.4.10 are:  The general clustering of recorded movements toward the lower end of the flow range reflects the timing of salmon arrival and movement up the river;  Overall, a significant majority of salmon movements through the fish counter are of relatively low level (<10/day) and this is the case right across the flow range (2.3 m3/s to 47.6 m3/s (198.72 to 4112.64 Ml/d)). The median daily count (excluding days on which no salmon movements are recorded) is 2/day. These low-level events combine with more exceptional daily movements ranging from 20- to well over 100-per-day. The mean daily count (excluding days on which no salmon movements are recorded) is therefore higher than the median, at just under 5/day; and  There are no major upstream movements (>20/day) when flows are less than 5 m3/s (432 Ml/d). Further insight into the observations above is provided in Figure 6.4.11, which is reproduced from a review of the salmon counter data undertaken on behalf of the EA by Pisces Conservation Limited (Pisces, 2010). It is important to note that the fish counters are positioned well above the tidal limit and hence the counter data does not represent the pattern of return to the river but instead captures the pattern and magnitude of movement through and beyond the lowermost reaches of the river.

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6.4.4.3. Monthly Data (1996–2010) The very distinctive temporal distribution in the movement of salmon shown in Figure 6.4.11 suggests that some further disaggregation of the data is required. Figure 6.4.12 shows the 1996–2010 data disaggregated by month from May to December and plotted against the flow on the day on which the salmon were counted moving upstream. Relevant summary data for each month is provided below in Table 6.4.2. Figure 6.4.12 and Table 6.4.2 show that there are considerable changes as the year progresses in the empirical relationship between daily salmon movements and residual flow. In May, 186 salmon were counted between 1996 and 2010 moving upstream on 110 days with an average gap between recorded events of 3.9 days). The mean number of fish per event was 1.7 and a single event exceeded 5 on only three occasions. The maximum event was 7 salmon/day. In summary, there is a consistent low level of fish movement and the pattern of movement appears to be unrelated to the residual flow in the river. In June, the general situation is very similar but with a discernible rise in salmon movements recorded. In all, 422 salmon were counted moving upstream on 182 days with an average gap between recorded events of 2.3 days. The mean number of fish per event increased to 2.3 and single events >5 occurred on 9 occasions. The maximum event was 11 salmon/day. In July, there is a further significant rise in activity, with 632 salmon counted on 251 days (average gap between events of 1.7 days) and an increase in the mean number of fish per event to 2.5. There was also a sharp rise in single events >5, which occurred on 27 occasions. These events tend to cluster at the lower end of the flow range (<5 m3/s (432 Ml/d)). The maximum event was 12 salmon/day. In August, salmon activity reduces again quite sharply. Only 411 salmon were counted (less than in June) and the frequency of events reduced to once every 2.8 days. Although the mean size of an event was similar to June and July, the number of events >5 was 14, half the number seen in July. There were, however, three events in excess of 15 salmon/day, including one major event of 46 salmon/day following a very intense

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Table 6.4.2 Monthly summary data (1996–2010)

May June July Aug Sept Oct Nov Dec

Total Days 434 420 434 434 420 434 420 434 Total Salmon Counted 186 422 632 411 436 2909 1993 582 Event Days 110 182 251 156 131 288 293 188 Events with Count>5 3 9 27 14 16 104 117 23 Mean Salmon/event 1.7 2.3 2.5 2.6 3.3 10.1 6.8 3.1 Max Count (per day) 7 11 12 46 33 122 62 23 Days between events 3.9 2.3 1.7 2.8 3.2 1.5 1.4 2.3 Flow range of 3.81 – 3.04 – 2.48 – 22.52 – 2.31 – 2.74 – 4.24 – 6.28 – 3 events (m /s) 36.79 42.16 20.06 11.43 11.61 38.80 41.01 47.58 Flow range of 329.18– 262.66– 214.27– 1945.73– 199.58– 236.74– 366.34– 542.59– events (Ml/d) 3178.66 3642.62 1733.18 987.55 1003.10 3352.32 3543.26 4110.91

In September, the situation is similar in some respects to August but with some distinct differences. The overall salmon count is 436, lower than July but an increase on August, although the frequency of events is still very low at once every 3.2 days. Events with counts >5 are still lower than July, at 16. However, the mean size of each event is higher than previous months at 3.3, and the maximum event is 33 salmon/day, which is also high. In summary, relatively little happens in September but when it does it tends to mostly be of greater magnitude than in previous months. Whilst the highest events (in the 20–40 range) all occur at flows above 7 m3/s (604.8 Ml/d), other events are scattered across the observed flow range. In October, the pattern of events changes dramatically. The total salmon count is 2,909; there is, on average, an event every 1.5 days; the mean size of each event is 10.1 salmon and there are 104 events >5 counts. The maximum event is 122 salmon/day and although the higher events (>20) all occur above 5 m3/s (432 Ml/d) there remain a significant number of events at flows lower than this. In November, the pattern of events is a slightly more controlled version of that in October. The total salmon count is slightly down at 1,993 but the frequency of events remains very high, with on average an event every 1.4 days. The events >5 also remains very high at 117 but there is less extreme variation in event size, with the mean event reduced to 6.8 salmon and a maximum event of 62 salmon/day. Apart from the highest (>30), events are scattered right across the flow range. In December, the pattern is essentially a muted replica of that in November as the number of salmon still downstream of the counter is at a much lower level. Total count is 582, with an event every 2.3 days on average. There are only 23 events >5 and the mean event is 3.1 salmon. The maximum event is 23 salmon/day. As in November, events are scattered fairly evenly right across the flow range. What is apparent from Figure 6.4.12 is that if the residual flow in the Great Test is a primary factor in the timing of the migration of salmon upstream then the responsiveness of salmon to this flow varies significantly depending on the time of year. Furthermore, the distribution of the data across the flow range in each month suggests that a significant factor(s) other than, or in addition to, the absolute flow are stimulating (or facilitating) the upstream movement. These factors are explored further in the sections below which first examine the annual time series of flow and salmon movement and then assess the possible pattern of arrival of salmon in the estuary and lower river.

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6.4.4.5. Use of the Mudeford Net Catch Data Figure 6.4.14 shows the weekly salmon net catch data from the Mudeford Nets at the entrance to Christchurch Harbour in Dorset. The data are averaged over the period 2000–09 and are further disaggregated by age class. Although most of the Mudeford fish will be heading for the Hampshire Avon, the Mudeford data are often used as the best available proxy for the pattern of arrival of salmon in the other chalk rivers in Southern England. Attention was has already been drawn to the small peaks of salmon movement recorded at the Great Test fish counter in June and July, as shown in Figure 6.4.11. The pattern and timing of these peaks is compared with the Mudeford arrival data in Figure 6.4.15, using an exaggerated scale for the Test counter data. The remarkably close match between the two curves suggests that the distinct but minor peaks in the Great Test data in June and July may be indicative of a very similar arrival profile to that of the Hampshire Avon population. A very similar pattern is also observed on the Little Test. The suggestion is that whilst only a small proportion of the arriving salmon are moving up past the counter on the Great Test, the proportion is sufficient to provide a trace of a much larger number of fish that have arrived but remained in the estuary of the lowermost reaches of the river. Although there will no doubt be some salmon arriving in the Lower Test after the end of July, the comparison with the Mudeford data suggests that most fish will have arrived by early August. Whether or not the age class distribution of the Test salmon are similar to that of the Mudeford data is less certain, although it appears reasonable to assume that the June arrivals will have a higher proportion of multi-sea winter fish (primarily 2SW) compared with July, which is likely to be dominated by grilse. Both the timing and age-class split is consistent with the observations of anglers and the available rod catch data.

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The data reviewed in the previous sections seems to provide the basis for a fairly coherent conceptual understanding of salmon behaviour on the Great Test. The key data are summarised in Figure 6.5.1 and are presented as average annual time series over a 10–15 year period (depending on the data record). A conceptual “model” describing salmon arrival in the estuary and subsequent movement up the Great Test is then proposed. This is sub-divided into five behavioural phases which are also shown on Figure 6.5.1. Whilst specific patterns of behaviour may vary from year to year, the conceptual model describes what appear to be consistent trends over the 15 years for which salmon counter data are available.

6.5.1. Phase 1: April and May

Salmon start to arrive in the estuary in small numbers in late April and May (yellow line). This is relatively soon after the onset of the recession in flows and flows are still reasonably high (blue line). Water temperatures are also relatively cool (red line). Although small in number, most of the arrivals will be larger multi sea winter fish (MSW) if the breakdown in sea age is similar to that at Mudeford (Figure 6.4.14). It seems likely that these fish move up the river as and when they choose and there is a small but steady count of salmon at Nursling in most years (see annual time series in Figure 6.4.13).

6.5.2. Phase 2: June to early August

Salmon arrival in the estuary starts to increase rapidly at the end of May and continues through June. A more significant surge in arrival then occurs in July and continues through to the end of July or early August before tailing off rapidly. While it is likely that a reasonable proportion of June arrivals are MSW salmon, the July and August arrivals will be predominantly grilse. Water temperatures increase through June and generally peak in July and early August. Flows recede and are at or close to a minimum by the end of July; as with all chalk rivers, the low flow period will then extend until recharge of the aquifer commences in the autumn. As discussed previously, the count data suggest that in most years a small proportion of the fish arriving in June and July move upstream past Nursling and there is some indication in the annual time series (Figure 6.4.13) that rainfall induced changes in flow may induce some of this movement. By implication, however, the vast majority of fish remain downstream of Nursling, either in the estuary or the lower reaches of the river. Figure 6.5.2 (provided by David Solomon based on data provided by the fishery at Testwood) shows the recorded rod catch of salmon at the Testwood fishery and the daily counts of salmon at Nursling in 2004. The data, which reflect a common pattern seen in other years, tend to support the suggestion that from early July through to the end of September significant numbers of salmon are present in the lowermost reaches of the river but are not inclined to move further upstream. Figure 6.5.3 shows the number of fish that have moved past Nursling on the Great Test by mid August as a proportion of the total ICES Returning Stock Estimate for that year and plots this proportion against the RSE. The data suggest that as returning stock increases a higher proportion of fish will remain in the lower river (or estuary) until the autumn. This may well be because the increased RSE is dominated by later running grilse.

6.5.3. Phase 3: August to Mid September

During this period river flows are generally at their lowest. Water temperatures are generally declining from a peak at the end of July. Although there will no doubt be some late arrivals, it is probable that most salmon will have arrived in the Test estuary by early August. Following the small but noticeable “peaks” in salmon counts at Nursling from

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6.5.4. Phase 4: Mid September to end of October

Following several weeks of apparent inactivity, the frequency and magnitude of salmon movement past Nursling starts to increase rapidly, with the majority of events being associated with rainfall induced peaks in flow. Whereas in previous weeks significant clusters of salmon only responded following intense weather events, by late September relatively small changes in flow (<1 m3/s (86.4 Ml/d)) can induce more than 20 salmon to move upstream (e.g. 2007). By early October it appears that significant numbers of salmon are ready to move and most rainfall induced peaks in flow will be associated with significant clusters of salmon moving upstream. In a normal year salmon movements past Nursling will peak in October. In relatively dry periods with reasonably stable flows, however, the numbers of salmon moving upstream can remain low (e.g. see plots for 1996, 1997, 2002, 2003, 2005 and 2007 in Figure 6.4.13), despite significantly reduced water temperatures. Thus, while the readiness of salmon to move upstream appears to increase rapidly in this period, a visual inspection of the plots in Figure 6.4.13 reveals that the pattern of movement in this period is strongly associated with distinct flow events rather than the magnitude of the underlying baseflow.

6.5.5. Phase 5: November and December

This period sees a decline in salmon movements past Nursling from the October peak and this is to be expected as the numbers of salmon remaining in the estuary and lower river decline. The frequency and magnitude of movements are still high, particularly in November, and while some surges of movement upstream are clearly associated with specific weather events, the general association of salmon counts at Nursling with changes in flow is less clear. By the end of December salmon migration upstream of Nursling is essentially complete.

6.6. The pattern of delayed migration

As discussed above, the majority of salmon returning in any given year will have arrived in the estuary or lower river by early August and yet on average only 25% of them move up the river past the Nursling and Conagar fish counters before the middle of September (this marks the end of Phase 3 in the conceptual model above). Whilst this general pattern of delayed migration is also observed in other rivers in the southern part of the UK, it is important in the context of this investigation, and specifically the EA‟s environmental objectives, to understand whether this pattern of upstream migration is “natural”, given the time of year at which the salmon arrive, or whether it is constrained in any substantive way by the manner in which the river is managed. The pattern of delayed in migration is important for two reasons:

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6.6.1. Comparison between the Great and Little Test

Figure 6.6.1 shows the average profile of salmon counts (1996–2010) at the fish counters on the Great and Little Test. It also shows the average flow hydrographs over the same period. The Little Test is different to the Great Test in several respects:  It has no impoundments in its tidal reaches and so has a much more “natural” tidal interface;  It has one minor impoundment further upstream at Conagar Bridge, which requires a fish pass;  It is a smaller river, with flows rarely exceeding 3 m3/s, even in winter months; and  It has a very stable flow regime all year round. Over the period from 1996 to 2010, about 65% of salmon migrated up the Great Test, with the remaining 35% moving up the Little Test. It is not known whether this ratio arises out of a specific preference for the Great Test or whether it is simply related to the relative size of the two rivers. Despite the differences between the two rivers, the pattern of salmon movement up the two rivers in Figure 6.6.1 is strikingly similar. On the Great Test, about 25% have moved through the fish counter by the end of September and on the Little Test the figure is about 30%. The degree of similarity between the data for the two rivers suggests that the pattern of migration is a characteristic of the salmon population itself and/or reflects constraints or “triggers” to movement that are common in both rivers.

6.6.2. Proportion of delayed fish and river flows on the Great Test

In Section 6.4.3 it was observed that there is no correlation between the annual RSE and river flows on the Great Test. However, the point was also made that the impact on spawning success, smolt migration and

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6.6.3. Seasonal changes in the responsiveness of salmon to the flow regime

6.6.3.1. Response to flow events A visual review of the annual time series plots in Figure 6.4.13 consistently shows salmon movement past Nursling responding to specific flow events following rainfall. Furthermore, the responsiveness to flow events seems to increases in the autumn compared with the summer. Figure 6.6.4 is extracted from the time series for 2009 and shows the same pattern. Three very similar flow events, two in the August to Mid September period and one in early October, occur following a rainfall event of between 10 and 20 mm. In each case river flow rises about 1 m3/s (86.4 Ml/d) from a base flow of just under 5 m3/s (432 Ml/d). The events in August and early September are associated with the movement of 2– 3 salmon upstream. However, an almost identical event in early October sees over 40 salmon move upstream. This consistent pattern of movement in the annual time series data suggests that salmon that did not move upstream soon after their arrival may generally not be inclined to do so, regardless of the flow conditions that prevail during and following their arrival. It seems probable that only an increasing “readiness to spawn” in the autumn months is likely to induce any significant numbers of salmon to move upstream.

6.6.3.2. Response to changes in velocity or depth Figure 6.6.5 shows the simulated velocities (top graph) and depths (bottom graph) at AP1 and AP4 on the lower Great Test in 2006 and 2007. Also shown (middle graph) are the corresponding time series data for river flows at the MRF point, salmon counts at Nursling, water temperatures and rainfall. The simulated velocities and depths were based on the gates at Testwood Mill being partially open (see Section 5.2 for more detail). River flows in the summer of 2006 were very low, reaching a minimum of less than 2.5 m3/s in September. Conversely, flows in the summer of 2007 were relatively high, remaining above 6 m3/s.

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6.6.4.1. Basic overview The Salmon Movement Model (SMM) was developed by Pisces Conservation Ltd based on technical inputs and suggestions by Dr David Solomon (Independent Fisheries Consultant), Dr Adrian Fewings (Fisheries Specialist at the EA) and the Atkins team undertaking the NEP investigation. The SMM simulates the numbers and timing of salmon moving upstream past the Nursling Fish Counter. The model provides a choice of several flow-based functions, some of which can be used in combination, together with optional functions to take account of temperature effects and the seasonal variability of the urgency with which salmon are seeking to move upstream to spawn. The model assumes that the timing of salmon arrival at the tidal limit (i.e. Testwood Mill) accords with the general distribution of arrival observed at the Mudeford fishery at the entrance to Christchurch Harbour in Dorset. Allowance is made in the model for varying the timing of arrival by plus or minus 7 days. Following their arrival, salmon are randomly assigned a probability of moving upstream past Nursling in accordance with the range of functions being employed. The parameters used by the model may include one or more of the following:  Daily residual flows on the Great Test (calculated at the MRF point);  Daily water temperatures (using the best available data in each year); and  Daily rainfall (based on an average from rainfall gauges in the area).

6.6.4.2. Functions available in the model Flow The SMM includes 3 possible flow-based functions: 1a. Flow Model 1 – this includes separate summer and autumn functions. The former is based on absolute flow alone and is derived from the relationship between observed salmon counts at Nursling and river flows between May 1st and 15th September. The autumn function is based on absolute flow but also incorporates a “change in flow” component and is based on the relationship between observed salmon counts and flows in the period from 16th September to 31st December. 1b. Flow & Rainfall – this is a single function covering the entire period from May to December. It is based on absolute flows but includes a component for rainfall based on the relationship between observed salmon counts and rainfall the preceding day. 1c. Flow (Power Function) – this includes a power function for the period 1st August to 15th September based on an approach suggested by Adrian Fewings. The use of the power function can be extended beyond this period or, alternatively, functions 1a or 1b above can be applied. In this document reference to the power function model refers to a version of the model which applies the power function from 1st August to 15th September and uses the rainfall & flow (1b) model for the May to June and mid-September to December period. Temperature The temperature function allows a minimum temperature to be set below which temperature has no effect on salmon movement upstream. A maximum temperature setting defines the point at which no salmon will move upstream. A linear transition is then applied between the minimum and maximum settings. The default settings in the model are 12°C and 16.4°C, based on observations in a published study. Willingness to move The concept behind this function is derived from a series of salmon tracking studies undertaken by David Solomon. In these studies it was observed that following arrival at the tidal limit of a river, the initial tendency of salmon appeared to be to move upstream if the conditions were suitable. If a salmon did not move upstream within 10–20 days, it was unlikely to do so until much closer to the spawning season. This,

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6.6.4.3. Use of the Model The SMM has been applied to each year for which good salmon count data are available from the Nursling counter. This covers the period 1996–2010, but excludes 2001 (no data) and 2009 (very poor data coverage). For each year, the number of salmon arriving at Testwood Mill is assumed to be equal to the number counted at Nursling that year. The model distributes the timing of arrival as described above and simulates their subsequent movement upstream. In this way, the model helps to explore the factors that may affect the nature and timing of migration upstream. It also provides an indication of the degree to which altering various parameters may prevent salmon moving upstream to spawn by the end of December in the year concerned. A significant number of model runs have been undertaken to evaluate which combination of functions produce a distribution that most closely matches the observed distribution. The model versions were evaluated as follows:  Using the goodness of fit tools incorporated by Pisces in the latest version of the model. This was based on application of the model to all 13 years in the 1996–2010 period; and  If the goodness of fit was reasonable (or at least comparable with the best values of other model versions), a multiple run (60 runs) of the model was undertaken for each year and the average outputs of all the runs across the 13 year period were then compared with the average observed counts for the same period.

6.6.4.4. Comparison of Core Flow Models Figure 6.6.6 compares the 13 year salmon counts for the 3 core flow models. Whilst each of the models significantly overestimates salmon movement in the summer, the power function version of the flow model simulates the shape of the curve most closely, including the reduced movement observed in August and early September in both the Great and Little Test.

6.6.4.5. Addition of Temperature & Willingness to move Based on the outputs above, the power function flow model was run with the temperature and WTM models set at their default values. The outputs are shown in Figure 6.6.7. It can be seen that the application of the temperature & WTM functions with default settings significantly over-constrains salmon movement in the summer months. Figure 6.6.8 shows the outputs from using the temperature function alone in combination with the Rain & Flow model. This illustrates the effect of the temperature function very well in that, however it is configured, it tends to over-constrain movement in early summer (June & July) and under-constrain it from mid-August through September as temperatures fall. While this does not mean that water temperature has no effect on salmon movement, it does suggest that it is not a major factor in the overall pattern of movement observed, in particular the reduced migration in August and September observed in most years.

6.6.4.6. Combination of Flow Models with WTM The best fit with observed data was generally obtained by combining one of the flow models with the WTM function. Figure 6.6.9 shows the outputs from the two combinations of functions that have produced the

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6.6.4.7. Annual model outputs Figure 6.6.11 compares the simulated and observed data for each of the 13 years in the 1996–2010 period. The figures show simulated data for the Flow model alone as well as for the Flow& WTM. As a general summary, the figures show that:  The general distribution of salmon movement between summer and autumn movement is well represented in all years except the two years with the highest flow summers;  The response of salmon to autumn flow and rainfall is generally very good, although in most years the model under-estimates the troughs in observed counts that occur in drier periods when flows are falling;  The general suppression of summer movement is simulated well, even in relatively high flow years such as 2000 and 2002. As indicated above, the exceptions to this are 2007 and 2008 where the combination of high baseflows and high summer rainfall gives rise to as significant over-estimate of summer movement; and  On close inspection, the more detailed patterns of salmon movement in the summer months in each year are not well represented. While it may be too much to expect the magnitude of what are generally small peaks to be replicated, there are relatively few occasions when observed and simulated peaks coincide i.e. the general precision in the simulation of movements in the autumn months is not replicated in the summer. The simulated movements in summer are driven by the flow model component, which tends to suggest that many of the generally small clusters of salmon which move upstream in the summer may be moving in response to factors other than river flow. Alternatively, the “patchy” pattern of movement in the observed data may simply reflect a more patchy pattern of arrival than the smooth curve included in the model.

6.6.4.8. Conclusions Although the salmon movement model cannot simulate salmon behaviour at a detailed level, it has proved useful as a qualitative tool for evaluating the timing and relative importance of some of the factors which may promote or hinder salmon movement. In this respect, the key points arising from the model development process are:  It is difficult for a flow based function alone to replicate the pattern of delayed migration, in particular the observed reduction in salmon movement in August and September. Such models consistently over- estimate salmon migration in the summer months, particularly in higher flow summers;  However the temperature function is configured, it tends to over-suppress salmon movement in June & July and over-predict salmon movement in August and September. While temperature may still be a factor in more extreme conditions (i.e. hot summers), this work suggests that it is not a major factor in the general pattern of salmon movement;

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6.6.5. Water Temperatures

6.6.5.1. Relevance of water temperature With regard to whether water temperatures constrain the summer migration upstream of salmon following their arrival in the estuary, several observations are relevant as discussed below. The reason that water temperature may be of concern is that the River Test, along with other salmon rivers in Southern England, is towards the upper end of what might be considered an optimal temperature regime for salmon. It is known that temperatures much in excess of 20°C are hazardous to the health of salmon. Figure 6.6.12 shows the average daily and maximum daily temperatures recorded at Romsey on the Test between 1996 and 2005. This is the best long term record available on the Lower Test but is approximately 12 km upstream of the Testwood abstraction; and as such it is likely that water temperatures in the reach between the abstraction and Testwood Pool will be a degree or so higher in the summer months compared with the Romsey record. Figure 6.6.12 shows that water temperatures in the Lower Test are generally between 15–18°C from June through to the end of August and that on relatively rare occasions they will exceed 20°C. This confirms that whilst the temperature regime is likely to be acceptable for most of the time, it is not always optimal. As summarised in Figure 6.5.1, most salmon are likely to be arriving in July as water temperatures are reaching a peak. Some previous studies (e.g. Solomon & Sambrook, 2004) have suggested that if salmon do not move up a river within 10–20 days of arriving in the estuary, they are likely to remain in the estuary or the lower reaches of the river until the autumn. At a qualitative level, a visual review of the annual time series plots in Figure 6.4.13 shows no readily discernible pattern between water temperatures and the upstream movement of salmon past Nursling, Whereas in most years the relationship between rainfall, changes in flow and recorded salmon movements in the autumn is very apparent, nothing stands out on a consistent basis in the summer months with regard to changes in temperature. It must be said, however, that it will be much more difficult at this level to discern any pattern if the primary effect of warmer temperatures is to cause a higher proportion of salmon to stop in the lower river for a sufficient period of time (as alluded to in 2 above) that they will no longer move upstream until the autumn spate flows whatever the temperature conditions in the intervening period. On a more quantitative level, Figure 6.6.13 shows the relationship between average water temperatures in July and August and the proportion of the annual salmon count in the summer months on the Great Test. Figure 6.6.14 shows the same data but for the Great and Little Test combined. Although the overall relationship based on 13 years data shows no significant trend, the warmest year (2006) also shows the lowest proportion of summer movement on the Great Test. The notable differences in 2006 between salmon movement on the Great and Little Test were discussed previously in Section 6.6.2.

6.6.5.2. The Thermal Model of the Great Test In addition to ensuring that the flow regime downstream of the Testwood abstraction allows safe passage of salmon upstream, the NEP investigation needs to assess the potential effect of reduced flows due to abstraction on water temperatures. For this purpose, a bespoke thermal model has been developed of the reach downstream of the abstraction to Testwood Pool. In view of the previous discussions on the increased tidal effects at low flows, however, it should be noted that the model does not take account of tidal effects but assumes constant velocities and depths for given flows and that the gates at Testwood Mill are partially open.

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Table 6.4.3 Key results from the thermal model of the Great Test Days in the year Days in the year where peak where peak Maximum Temp (°C) temperature >20°C temperature >21°C Zero abstraction 5 0 20.5 Full licence 5 0 20.8 MRF 3 13 4 21.5 (constant flow of 1.05 m /s)

6.6.5.3. Cumulative temperature effects A further question raised by the EA regarding potential abstraction induced increases in temperature is whether there may be any cumulative implications for the health of those salmon already in the river or waiting further downstream.

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6.6.6. Impounding Structures

The role of the structures at Testwood Mill in regulating the flow regime downstream of the abstraction intake at Testwood was discussed in some depth in Section 6.3. The purpose of this section is to assess other means by which the structures at Testwood Mill may constrain migration upstream and thus contribute to the pattern of delayed migration of salmon upstream. The means by which this might occur include:  By acting as a physical barrier to movement;  By reducing the velocity of the river upstream of the impoundments to such an extent that salmon are not inclined to move out of the faster, freely flowing conditions (at low tide) downstream of the impoundment; and  By creating attractive conditions downstream or immediately upstream of the impoundment for fish which do not have a strong inclination to move upstream. These are discussed in turn below.

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6.6.6.2. Effect on velocities upstream of the Testwood Mill Impoundment There is no doubt that, by definition, the impoundments create a low velocity regime upstream. However, as discussed in Section 6.6.3, an assessment of the outputs from the hydraulic model and the pattern of salmon migration indicate that the latter occurs almost irrespective of the velocity regime upstream of the impoundments (at AP4).

6.6.6.3. Creating attractive conditions downstream and immediately upstream of the Testwood Mill Impoundment In his review of the effect of the Testwood Mill structures on behalf of the EA in 2005, David Solomon stated the following: “Testwood Pool represents a very good environment for salmon to hold safely and in comfort, with deep water, steep banks, breakwaters, rocks, gravel banks, weed beds, cover represented by white water, and a wide range of flow velocities in a limited area. Similarly, the

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6.7. Risks to salmon remaining downstream

One of the key conclusions arising from the sections above is that there is a strong body of evidence that that the pattern of delayed salmon migration observed in the Great and Little Test is primarily a behavioural characteristic of the salmon. In other words, when a salmon chooses to move upstream, it will not be hindered from doing so by the flow or temperature regime or the structures at Testwood Mill. While this seems to be clear, what is less clear is how those fish that remain downstream are affected by the estuarine environment, particularly at low tide. The fish counters provide an excellent quantitative record of the pattern and numbers of fish that make it upstream into the main River Test and the rod catch data provide a good qualitative record over a much longer period of time. However, neither can account for those fish that may have returned to the estuary but do not make it to the river. Solomon and Sambrook (2004) analysed radio-tracking data from five rivers in Southern Britain (including the Hampshire Avon) and noted that hot dry summers were associated with salmon delaying river entry and suffering significant losses; those lost would of course never appear at the counter sites. So how significant might this affect be on the Test salmon population and what level of risks is posed by the Testwood abstraction to those salmon which remain in the estuary? Although there is no direct measure of the numbers of fish returning to the estuary, or the proportion of the population that may be lost in this phase of their life cycle, the existing body of information does provide some relevant insights on this issue and these are summarised below.

6.7.1. Potential effects of abstraction on the estuarine environment

1. The thermal modelling on the Great Test demonstrated that the prevailing weather conditions are the major determinant of water temperatures rather than river flows and the potential influence of the abstraction on the temperature regime was therefore very minor. This influence would be further dissipated in the estuary at low tides as flows from the Great, Middle and Little Test meet and even more at high tide. 2. As described previously, the tidal influence on the flow regime is already strong at Testwood Mill. This will obviously increase significantly moving downstream where it meets the Middle and Great Test and the channel is increasingly modified and deepened through dredging. In this context, it is difficult to envisage that the abstraction could have any substantive effect on the estuarine environment experienced by returning salmon.

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Notwithstanding the fact that an unknown proportion of salmon may return to the estuary but not enter the river, there is good evidence (e.g. Figure 6.5.2) that in the summer months many fish that do not pass the fish counters in the summer months are in the lower reaches of the river (i.e. the Testwood and Nursling beats) rather than further downstream in the estuary. Although interpretation of annual RSE data must be treated with caution for reasons explained in Section 6.4.1.1, the warmest low flow years (1989, 1990 and 2006) in the record had returning stock estimates that were average or above average. Whilst this of course does not preclude the possibility of losses in the estuary, for the reasons outlined above and within the confines of very limited data it does suggest that the scale of losses in these years are unlikely to have been significantly greater than in other years in the record.

6.7.3. Further Monitoring

Whilst the risks associated with the Testwood abstraction to salmon remaining downstream appear to be low, the relative scarcity of data regarding salmon behaviour in the lower river and/or estuary would benefit from additional monitoring and review over the next 5–10 years to build the evidence base, alongside the ongoing maintenance and improvement of the fish counters and improved monitoring of tidal and water temperature regime.

6.8. Conclusions

Sections 5 and 6 provide a comprehensive review of how the full range of possible abstraction at Testwood might affect various components of the flow regime in the Great Test. This has focused particularly on low flow conditions but used higher flow conditions for comparative purposes. Section 6 has then focused on what can be learned from the available data relating to salmon migration in the Lower Test and evaluated the relationship between flows and temperatures on the Great Test under a range of weather conditions. The conclusions below are framed by the EA‟s Environmental Objectives set out in Section 6.1.

6.8.1. Environmental Objective 1: The Testwood abstraction must support a flow regime in the lower River Test that maintains or improves passage for migrating salmon

The conclusion of this assessment is that the Testwood abstraction is highly unlikely to hinder the passage of salmon upstream, even in very low flow periods that extend below those observed historically. A similar conclusion is drawn with regard to the effect of the impoundments at Testwood Mill.

The main points underlying this conclusion are as follows: 1. The reach downstream of the abstraction is naturally tidal – modelling of the complex interaction between the tide, the structures at Testwood Mill and river flows strongly suggests that abstraction at Testwood would not hinder the passage of migrating fish. The nature of the flow regime is such that this conclusion extends to flows as low as the MRF defined in the Testwood licence. Furthermore, the channel surveys and hydraulic modelling have demonstrated that the flow regime in the reach downstream of the Testwood intake but upstream of the confluence with the Blackwater will support the passage of migrating salmon under extreme low flows such as the MRF. 2. Following their arrival in the lower reaches of the river between June and early August, most salmon (70%) do not move upstream until the autumn when they are ready to spawn – there is good

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The majority of salmon move up the Great Test rather than the Little Test. This is true in both the summer run (May to September) and the autumn run (October to December), despite the impoundments at Testwood Mill and the abstraction at Testwood. 4. The numbers of salmon moving upstream in recent low flow years compares well with salmon migration in high flow years

Although of limited credence in isolation due to the range of intra and extra-catchment factors that can affects the numbers of returning salmon in any given year, as a supplementary component of the evidence base it is notable that in some of the warmest low flow years in the last 50 years (e.g. 2005 and 2006) salmon counts on the Great Test and overall spawning escapement were well above the average for the last 20 years.

6.8.2. Environmental Objective 2: The Testwood abstraction intakes must be effectively screened to prevent fish being drawn in and trapped at any stage of their life cycle

Southern Water is funded in its “AMP5 Business Plan” (2010–2015) to undertake a major upgrade and refurbishment of the Testwood Water Treatment Works. This will include works to ensure that the abstraction intakes are screened in a manner that complies with the latest EA guidelines. As such, steps are already in place to comply with this objective and no additional work in this regard has been undertaken in the NEP investigation.

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It is important to note in this context that any reduction in river flow will lead to an increase in daytime temperature, however small. As with all other assessments of this nature, therefore, the criterion applied here is whether the rise in temperature caused by abstraction constitutes a significant risk to the salmon or sea trout population in the Lower Test (sea trout may be more sensitive to high temperature than salmon). The conclusion of this assessment is that the Testwood abstraction would not cause a significant rise in temperatures, even under low flow conditions in warm summers. The use of the thermal model to evaluate the temperature regime under extreme low flows also suggests that the abstraction will not compromise the resilience of the lower Great Test to climate change.

These conclusions are primarily derived from the use of a thermal model to test various flow scenarios on the Great Test downstream of the Testwood abstraction under a range of climatic conditions. The key elements underlying the conclusions are: 1. The dominant determinant of water temperatures is the prevailing climatic conditions – temperatures in a cool summer such as 2008 would be 2–4ºC cooler than a very warm year such as 2006 based on the same flow regime. 2. Differences due to changes in river flows are marginal by comparison – with continuous abstraction at full licensed quantities in the very warm low flow year of 2006, the average increase in temperatures in July due to the abstraction was 0.08ºC. The maximum hourly difference due to abstraction was predicted to be 0.4ºC in mid-afternoon in early September when river flows were at their lowest. 3. Potential cumulative effects are negligible – consideration of the cumulative effects of small changes in temperature over several months for a salmon resting up downstream of the abstraction suggested that the cumulative difference in temperature would be almost negligible compared with the equivalent differences experienced by salmon from one year to the next on the River Test or on other rivers such as the Itchen and Hampshire Avon, both of which are generally warmer than the Test. 4. Using temperature in the salmon movement model to constrain salmon migration did not work well – this suggested that the temperature regime on the Great Test is not a major factor in the movement of salmon upstream.

6.8.4. Environmental Objective 4: The Testwood abstraction must support a flow regime that maintains or improves water quality in the River Test for salmonid populations

With regard to water quality, the EA scoping work for this NEP investigation made it clear that the principal water quality risk to the River Test salmonid populations arises from high sediment loads and siltation of spawning gravels. The EA indicated that the Testwood abstraction is not considered to be a material contributor to this risk. With regard to the Testwood abstraction, therefore, this objective has been met.

6.8.5. Other fish species

As stated in Section 6.1 the primary focus of the fisheries assessment in the NEP investigation would be on the salmon population, given the sensitivity of these species. If effects of the Testwood abstraction on the salmon population are considered to be significant, however, further assessment of the potential effects on other species may also be required.

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This section details the results of the ecological appraisal undertaken for key habitats and species for the Lower Test NEP. Given access restrictions to the channel of the Great Test during the period of the fishing season (February to end of September) it was not possible for full surveys to be undertaken due to access restrictions. Therefore surveys were undertaken to collect as much information as possible, and data or survey results that were already available have been used in the appraisals.

7.1. Ecological Flow targets

7.1.1. Environment Agency CAMS-2 results

Section 1.6 provides an introduction to the Environment Agency‟s CAMS and WFD processes, and the Environmental Flow Indicators (EFI) that are used to indicate ecological flow stress. This section details the application of the WFD and CAMS approach to the Lower Main River Test. The study reach of the Lower Test NEP investigation falls within CAMS reach “AP16 River Test Total”, which has been identified by the Environment Agency as having moderate sensitivity, and therefore is classed as having an Abstraction Sensitivity Band (ASB) of 2. This classification means that the EFI at a Qn95, or the percentage of allowable flow reduction by licensed abstraction, is 15% of the natural flow at that flow exceedance. The percentage of allowable abstraction increases as the flow exceedance increases as shown in Table 7.1.1. Figure 7.1.1 and Table 7.1.2 shows the results from the Environment Agency‟s CAMS-2 assessment for AP16 which compares the different flow scenarios against the WFD EFIs appropriate to ASB 2. The results show that at all flow thresholds (e.g. Q95 etc), the River Test is „compliant‟ for the historic scenario i.e. flows are above the EFIs set for the River. The results also show that flows under the fully licensed scenario are non-compliant from Q59 to Q100 i.e. flows are less than the EFIs. This means that there is a possibility that fully licensed flows may affect the ecological community of the river, from discharges equivalent to Q59 to Q100 at the Assessment Point i.e. flows of 655 M/d and lower.

Table 7.1.1 Percentage of „allowable‟ flow reduction by licensed abstraction

Point on Flow Duration Curve Abstraction Sensitivity Band (ASB) Q30 Q50 Q70 Q95

3 (most sensitive) 24 20 15 10

2 26 24 20 15

1 (least sensitive) 30 26 24 20

Percentage of allowable flow reduction (from naturalised) at each ASB and Flow Duration curve point

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Flow scenarios Historic Fully Licensed

Not compliant: flows dip below the Q99 Compliant: flows are above the EFI threshold at Q59 i.e. 7.58 m3/s, 655 Ml/d

Not compliant: flows dip below the Q95 Compliant: flows are above the EFI 3 threshold at Q59 i.e. 7.58 m /s, 655 Ml/d

Q70 Compliant: flows are above the EFI Compliant: flows are above the EFI

Q50 Compliant: flows are above the EFI Compliant: flows are above the EFI

7.1.2. Consideration of AP16 as a Transitional Water

The location of the CAMS-2 Assessment Point 16 is in an area of the river which is directly affected by the tidal regime. There is an argument therefore that the freshwater flow EFIs are not applicable at this point, but that the approach for transitional water should be applied instead. A reach that is considered to be transitional9 is assigned an abstraction sensitivity band of „high‟, „medium‟ or „low‟ abstraction sensitivity depending upon the volume of freshwater in the tidal prism/wedge (high to low respectively). On the precautionary basis that the abstraction sensitivity is „High‟ for the Lower Test at Assessment Point 16, the percentage of allowable abstraction for „high abstraction sensitivity‟ for transitional waters is higher than for freshwater flow as shown in Table 7.13, by a minimum of 15%. That is, the allowable abstraction can be 25% at flows lower than Q95, rising to 35% at Q70 for example. Figure 7.1.1 shows that under fully licensed abstraction, the freshwater EFI is breached at Q59 at the CMAS- 2 AP16. While it is not possible to reproduce the output of the Environment Agency results outside of the CAMS-2 ledger in order to check where the fully licensed abstraction would dip below the transitional water threshold, the data as shown in Figure 7.1.2 suggests that fully licensed flows may not breach the allowable percentage, or would do so at much lower discharge (higher Q percentile) than Q59.

Table 7.1.3 Comparable percentages of „allowable‟ flow reduction by licensed abstraction for fresh and transitional water bodies

Percentage of „allowable‟ flow reduction by licensed abstraction Abstraction Sensitivity Band (ASB) Q70 Q95

Freshwater – Medium 15 10

> Q95 = 30% Transitional water – High 35 < Q95 = 25%

9 The WFD defines transitional waters as “...bodies of surface water in the vicinity of river mouths which are partly saline in character as a result of their proximity to coastal waters but which are substantially influenced by freshwater flows.” See p27 of http://www.eutro.org/documents/wfd%20cis2.4%20(coast)%20guidance%20on%20tcw.pdf

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As stated in Section 1.6.3.2, the location of AP16 includes the flow of the Main Test, Little Test and the Blackwater channels. In the Lower Test NEP investigation however there are two reference points for the assessment of the Testwood PWS abstraction: at Testwood GS, which is immediately downstream of the intake for the abstraction; and at the MRF location, which is downstream of the Blackwater confluence. Therefore in order to inform the Lower Test NEP Investigation, analysis has been undertaken to assess the equivalent discharge at which river flow would dip below the EFI for Testwood GS and at the MRF location. Section 7.1.2 proposes that the CAMS-2 AP16 should actually be considered as transitional water, rather than freshwater, given the influence of the tidal regime at this location. This would mean that the percentage of allowable abstraction pertaining to transitional water should be applied, rather than the EFIs for freshwater bodies. Given the results of the hydraulic model in showing the effect of the tidal regime along the study reach, there is also a strong argument that the study reach downstream of the Testwood gauging weir could also be considered as transitional waters. While the tidal regime dominates the study reach in terms of its effect upon water level and water velocity, the effect upon water chemistry is not as well known. The structures at Testwood Mill structures prevent the upstream migration of saline water, which is a feature of the WFD of such water bodies. Therefore in order to assess the EFIs at Testwood GS and the MRF, it has been decided to take both approaches (freshwater and transitional water) in order for consistency with the Environment Agency approach. The approach taken therefore has been to create a freshwater EFI and a transitional abstraction threshold time series for Testwood GS which is based on the allowable abstraction volume from naturalised freshwater conditions at Testwood GS, as per Table 7.1.1. The same approach was also followed for naturalised flow at the MRF location. Figure 7.1.2 shows the results of the above approach, and shows the abstraction thresholds for Testwood GS and the MRF point, plus the abstraction scenarios as a flow duration curve. Table 7.1.4 presents the flow data at the point of exceedance. For the freshwater EFIs, the figure shows that the threshold is exceeded at both locations, i.e. flows go below the threshold. At Testwood GS (Figure 7.1.2a) the historic abstraction scenario exceeds the Testwood GS EFI at Q87; the fully licensed abstraction scenario exceeds the Testwood GS EFI at Q56. At the MRF location (Figure 7.1.2b), the historic abstraction scenario exceeds the MRF EFI at Q95; the fully licensed abstraction scenario exceeds the MRF GS EFI at Q69. Examination of the transitional water thresholds, shown in Figure 7.1.2, reveals that the threshold is not exceeded by the historic abstraction scenario at either location. The fully licensed abstraction scenario does however exceed the threshold. At Testwood GS (Figure 7.1.2a) the fully licensed abstraction scenario exceeds the transitional threshold at Q88; whereas at the MRF location (Figure 7.1.2b), the fully licensed abstraction scenario exceeds the transitional threshold at Q98.

Table 7.1.4 Exceedance of the freshwater EFI thresholds

Transitional water Transitional water Freshwater EFI at Freshwater EFI at Abstraction threshold at threshold at the Testwood GS the MRF scenario Testwood GS MRF

Q87 Q95 Historic Not exceeded Not exceeded 2.88 m3/s, 249 Ml/d 3.45 m3/s, 298 Ml/d Q56 Q88 Q69 Q98 Fully Licensed 5.02 m3/s, 434 Ml/d 1.98 m3/s, 171 Ml/d 5.23 m3/s, 452 Ml/d 2.24 m3/s, 193 Ml/d

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As discussed in Section 1.6, the application of EFIs should be precautionary: where abstraction reduces flows below EFI thresholds, it is not an absolute indication that there is a consequent ecological issue. An assumption with EFIs is that the river under assessment is in a completely natural condition other than abstraction affecting its flow regime. This is not the situation with the Lower Test both due to the presence of water level control structures, and the effect of the tidal regime. It can be argued that the application of the freshwater based EFI to the Lower Test may not be appropriate given the dominance of the tidal regime and the altered physical nature of the Lower Test, especially if the existing structures and modifications are not to be removed. The allowable abstraction threshold for transitional waters is certainly appropriate for the CAMS-2 AP16 location, and is also relevant to the MRF location and also Testwood Gauging Station, given the results from the hydraulic model (Section 5.2) that show the influence of the tidal regime can extend this far upstream. The freshwater EFIs and the transitional water allowable abstraction threshold are presented as an absolute or a fixed flow quantity – however given that they are guidelines to identify a risk to the ecology (and WFD status), and the context of the tidal and modified nature of the study area, further investigation is required to determine whether this risk is significant, and undertake a site specific assessment to examine actual conditions what any impact might be. Therefore this NEP study serves to investigate in detail the potential effect of the Testwood PWS abstraction by looking at specific ecological receptors. As stated above, Section 5.2 examines in detail the effect of the abstraction upon flows, water velocities and water levels along the study reach against the background on the significant tidal regime that affects the reach. These findings are considered within Sections 6, and 7.2 to 7.8 to examine the actual effect of the abstraction upon specific ecological receptors and their hydroecological requirements to determine the significance of the effect of the abstraction.

7.1.4. SSSI Flow Targets

As stated in Section 1.6.4, Flow Targets have been set by Natural England, as shown in Table 7.1.5. Compliance with SSSI targets is required to achieve favourable SSSI condition, which is underpinned by legislation (Wildlife and Countryside Act 1981 and the Countryside and Rights of Way Act 2000). Figures 7.13 and 7.14 show the abstraction at Testwood in relation to the SSSI Flow Targets. At Testwood GS it can be seen that the abstraction exceeds these flow targets in all years except for 2007 and 2008 under the historic abstraction scenario. At the MRF location, historic abstraction exceeds the thresholds in all years except 4; the fully licensed scenario exceeds the thresholds in all years. These results show that the SSSI flow targets are currently not being met. Historical abstraction has exceeded the flow target in most years, and full abstraction will exacerbate this failure to comply with the conservation objectives for the site.

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Equivalent flow at Testwood Equivalent cumecs (Ml/d) Allowable % Scenario GS at the MRF abstraction

Naturalised flow is more than: Naturalised flow is more than: Abstraction must not When river flow is high to 7.31 cumecs 8.98 cumecs exceed 20% of average (Q1 to Q50) 631.2 Ml/d 776.1 Ml/d naturalised flows Naturalised flow is between: Naturalised flow is between: Abstraction must not When river flow is average 3.03 to 7.31 cumecs 4.21 to 8.98 cumecs exceed 15% of to low (Qn50 to Qn95) 261.8 to 631.2 Ml/d 363.4 to 776.1 Ml//d naturalised flows

Naturalised flow is less than: Naturalised flow is less than: Abstraction must not When river flow is low to 3.03 cumecs 4.21 cumecs exceed 10% to 15% of lower (Qn95 to Q100) 261.8 Ml/d 363.4 Ml/d naturalised flows

As stated in Section 1.6.4, these flow targets are generic targets for chalk rivers and not specifically generated for the River Test. They indicate acceptable deviations from naturalised flow across the whole flow regime, and are designed to ensure that abstraction from a river does not impact upon the range of habitat factors of critical importance to characteristic flora and fauna (including macrophytes, invertebrates and fish), and to protect the most sensitive reaches of a river within the natural constraints dictated by the river type. The study reach, as discussed in Section 3.8 has been significantly modified by the construction of the mills, associated weirs, new channel cuts, channel straightening, off-take structures and gauging weirs. The geomorphological assessment of the study reach concludes that the Lower Test exhibits lacustrine characteristics and more closely resembles a lake than a river, with slowly moving water. The backwater effect of the structures at Testwood Mill and the tidal regime can extend to upstream of the Testwood Gauging Station, and create an ecological signature that is dominated by aquatic species more common of lentic, sediment rich lowland rivers, rather than chalk stream habitats. Given the heavily modified nature of the study reach, and the effect of the tidal regime, the applicability of the flow targets to this reach, and the conclusions that could be drawn from these results are debatable.

7.2. Aquatic macrophytes

7.2.1. Introduction

This section reports the findings of aquatic macrophyte surveys in the River Test undertaken for this NEP investigation on the 17th July 2011 and on 6th October 2011. The surveys have been undertaken to provide baseline data on the aquatic and marginal plant communities present both upstream and downstream of the Testwood Surface Water Abstraction Point, for the Lower Test NEP investigation The macrophyte survey has been divided into 2 reaches for reporting and data interpretation purposes, namely: 1. Upstream of the Testwood Abstraction point (USTW):  Surveyed 6th October 2011  0.65 km, 2 sub-reaches  Upstream limit of survey at Nursling Weir pool  Downstream limit at Testwood Abstraction Point. 2. Downstream of the Testwood Abstraction point (DSTW):

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Table 7.2.1 River Test macrophyte survey upstream and downstream sub-reaches Testwood Pool Reach Extent Survey Reach Survey Date Top NGR Bottom NGR (m) Code USTW_01 06/10/2011 SU 35112 15820 SU 35130 15576 330 USTW_02 06/10/2011 SU 35130 15576 SU 35288 15330 320 DSTW_01 06/10/2011 SU 35288 15330 SU 35505 15185 270 DSTW_02 17/07/2011 SU 35505 15185 SU 35758 15059 330 DSTW_03 17/07/2011 SU 35758 15059 SU 36044 15158 400 DSTW_04 17/07/2011 SU 36044 15158 SU 36111 14864 350 DSTW_05 17/07/2011 SU 36111 14864 SU 36107 14554 300

Notes: Due to access constraints only 240 m of sub-reach DSTW_02 was viewable at survey.

7.2.2. Survey methodology and limitations

Survey limitations associated with differences in methodological approach, access constraints and time of survey are identified for each of the 2 survey periods below.

7.2.2.1. July 2011 survey The request by the Testwood Pool fishery owners for the surveyor not to enter the water, or to use common sampling devices (e.g. rope thrown grapnel), limited the July 2011 survey approach to one of observation from the bank side. The reason for the constraint was to avoid any possible fish disturbance during the fishing season. Therefore all reaches were surveyed from the true right hand bank with emergent species on the far bank recorded through binoculars. Water depths and water clarity on the day of survey were suitable for viewing in-channel macrophyte growth. Due to the river channel wetted width being on average between 15 m and 20 m in cross-section a number of the submerged species were only observable to approximately the central channel line. For these species, estimates of abundance were made for each reach by doubling the half channel width species cover value record. While the surveys were conducted by an experienced aquatic ecologist, it should be noted that the above constraints are unlikely to have resulted in an exhaustive schedule of the aquatic macrophytes for the reaches surveyed. Nevertheless, the methodology is considered to have provided a suitable level of detail in order to describe the general assemblage and identify changing character in species composition through the reach.

7.2.2.2. October 2011 survey In contrast to the July survey, the macrophyte survey in October 2011 was undertaken using a rope thrown grapnel. In order to provide a comparative approach to that undertaken in July the grapnel was only used to

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7.2.2.3. Species records For each aquatic macrophyte species recorded, an estimate of its percentage cover in the reach is provided using the nine point Species Cover Value (SCV) scale as described by Holmes et al. (1999), where the SCV is recorded as show in Table 7.2.2.

Table 7.2.2 Species cover values used in estimation of percentage macrophyte cover

Species Cover Value (SVC) Percentage cover C1 <0.1 C2 0.1–1 C3 1–2.5 C4 2.5–5 C5 5–10 C6 10–25 C7 25–50 C8 50–75 C9 >75 For each of the four reaches macrophytes species occurring within the wetted channel width a species cover value (SCV) has been provided, for those species occurring on the bankside i.e. generally outside of the influence of river flow and stage, a presence / absence is indicated (see Appendix 7.2.1).

7.2.3. Results

7.2.3.1. Species assemblages and morphological groups A total of 53 species were recorded at survey, the majority being observed exclusively within the wetted channel width. Six of the species observed were recorded in bankside habitats only. Figures 7.2.1 to 7.2.3 show the results of the surveys and a full species list for both is provided as Appendix 7.2. The following number of in-channel and marginal macrophytes was recorded in each sub-reach (excluding species recorded exclusively on the bankside / banktop areas):  USTW_01: 19 species;  USTW_02: 20 species;  DSTW_01: 21 species;  DSTW_02: 30 species;  DSTW_03: 33 species;  DSTW_04: 26 species; and  DSTW_05: 17 species. A general pattern of increasing species richness in the downstream direction is observed to sub-reach DSTW_04 from whence a marked reduction in species richness occurs, to a low of 17 species in the sub- reach immediately upstream of the Testwood Mill structures. This shift in a reduction in species richness is strongly influenced by the availability of marginal habitat and its ability to support fringing vegetation communities.

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Table 7.2.33 Abundance (SCV) of macrophyte groups in survey sub-reaches

Sub-reach Code Macrophyte Group USTW_01 USTW_02 DSTW_01 DSTW_02 DSTW_03 DSTW_04 DSTW_05 Submerged fine leaved C6 C7 C2 C2 C3 C6 C7 Submerged broadleaved C2 C5 C4 C4 C4 C5 C6 Submerged linear leaved C2 C3 C6 C6 C5 C7 C6 Floating leaved rooted C1 C1 C1 C2 Emergent broadleaved herbs C3 C3 C3 C3 C3 C3 C2 Emergent reeds/rushes/sedges C2 C3 C2 C3 C4 C5 C4 Free floating C1 C1 C1 C1 C1 Open water (%) 50 35 40 60 80 30 20

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7.2.3.3. Assessment of flow – Macrophyte Flow Rank (MFR) scores Macrophyte Flow Rank scores have been calculated (see Table 7.2.4) to assess dominant flow character as reflected by the assemblages present in each of the sub-reaches (after Holmes, 1999) and to provide a baseline for future comparative assessments (Table 7.2.4). Appendix 7.2 provides details of the macrophyte species used in production of this flow index and their individual Macrophyte Flow Ranks (MFR). The Flow Score for each sub-reach has been calculated as follows: = (∑CVS/∑SCV) where Cover Value Score (CVS) = SCV × Macrophyte Flow Rank This methodology differs slightly from that used as standard since it takes account of the SCV for each species. For completeness the score shown in brackets is that calculated using standard method in which the score reflects the average species flow rank for the assemblage. It is considered to be a less sensitive index of flow character than that adopted here. The individual sub-reach flow scores display a general reduction in a downstream direction between Nursling and Testwood Pool as shown in Figure 7.2.3. Below the Testwood Abstraction all macrophyte assemblage flow scores are less than 2.00 indicting that the plant assemblage contains a high proportion of slow flowing / lentic species. Above the abstraction point scores are greater notably higher (2.21 and 2.43) and indicate a high proportion of lotic species within a more free flowing riverine system. It is considered that the effect of the structures at Testwood on river flow character is of a magnitude that will mask any changes in plant community composition that could be attributed to the abstraction of water alone. In summary, whilst the macrophyte assemblage flow scores could be interpreted as showing a reduction in flow volume downstream of the abstraction point it is more likely to represent a response of the macrophyte community to reduced flow velocities created by the impounding structures at Testwood Pool.

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Table 7.2.4 Mean Flow Rank calculations for each sub-reach

Sub-reach Code MFR calculations USTW_01 USTW_02 DSTW_01 DSTW_02 DSTW_03 DSTW_04 DSTW_05

Cover Value Score 62 102 61 70 93 89 70 (∑SCVi * MFRi)

Species Cover Value (∑ of 28 42 31 36 47 48 38 individual SCV) Flow Score (FS) 2.21 (2.00) 2.43 (2.27) 1.97 (1.94) 1.94 (1.89) 1.98 (1.96) 1.85 (1.96) 1.84 (1.75) (Standard method)

Potamogeton pectinatus (L.)

Of particular note from the survey results was the sudden occurrence in the plant assemblage of the pondweed Potamogeton pectinatus at a distance of approximately 450 m upstream of Testwood Pool in the vicinity of the drainage channel discharge from Chadney Meadow (see Figure 7.2.1). P. pectinatus not only occurs as the most abundant species from this point downstream it was also unrecorded in all of the sub- reaches upstream of this point. It is considered that the localised distribution of this plant species indicates the presence of a significant environmental gradient. P. pectinatus can tolerate fluctuating levels (at least 0.5 –1.75 m in brackish waters, Kantrud, 1990), high nutrient concentrations and static water conditions and its presence may indicate the extent of the impoundment and / or the channel length most significantly affected by rising and falling river stage caused by twice daily tide lockout at the Testwood Pool structures. Furthermore the plant‟s ability to tolerate brackish water conditions and cope with high nutrient concentrations could potentially indicate a response to localised changes in water quality arising from the input of tidal water through the Chadney Meadow‟s ditch system or even through the hatches in the flow control structures at Testwood. The extent of the Normal Tide Level (NTL) shown on the background maps in Figure 7.2.1 lends strength to the supposition that saline water ingress may be occurring. In order to assess this possibility, salinity monitoring was undertaken for the NEP to assess the presence of any significant chemical gradients, see Section 5.1.3. The results show that spring surge tides can increase salinities in Testwood Pool, as observed on 28th November 2011 (see Section 3.6). However there is limited evidence for a regular saline incursion further upstream into the Great Test as sea levels are generally below river levels upstream of the structures on the Great Test. It is likely that, increased sedimentation rates immediately upstream of Testwood Pool, due to flow impoundment, may be playing a more important role in driving the species composition through changes in substrate quality that water quality.

7.2.3.4. Assessment using Ranunculus as an indicator species Instead of using a generic abstraction guideline, the results from the macrophyte sampling and hydraulic model analysis can be used instead. The hydraulic model results can be examined to determine the change to the hydrological regime that would be expected under historic and fully licensed abstraction with regard to water velocities. As stated above, the observed assemblage in the River Test has been shown to be atypical of a free flowing river, but one suited to the existing ponded and slow flowing aquatic habitat caused by the tidal cycle and the impoundment effect of the Testwood Mill structures. Nevertheless, the effect of the abstraction upon the potential for chalk stream flora should be determined by examining the changes to water velocity, as this is a key hydrological determinand for chalk river macrophytes. While the effect of abstraction upon river flow can affect the whole aquatic vegetation community, water crowfoot, Ranunculus spp. is commonly chosen as it is an indicator species for the health of the river

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Section 5.2.2 details the results of simulating different combinations of abstraction and structure scenarios to isolate and identify the effect of the tidal regime upon water velocities from the different influencing factors. The velocity duration curves shown in Figure 5.2.2a–c show the range of velocities experienced in the study reach for a range of abstraction and structure scenarios. Several aspects can be inferred from these charts:  Under conditions of no abstraction, there is a progressive downstream reduction of channel velocities in the Lower Test (i.e. from AP1 to AP4) due to the tidal effect and structure settings;  Water velocity is highest at high flows, and lowest at low flows;  Water velocities are highest when the structures are open; lowest when the structures are closed, due to the backwater effects caused by the tidal cycle and the structures themselves;  The effect of the abstraction upon water velocities is greatest at AP1; the effect of the tidal cycle and structures is greatest at AP4;  The range of velocities over the hydrological year is greatest at AP1 (immediately downstream of the abstraction) with a variation of up to 0.9 m/s over winter high flows and summer low flows, from closed and open structures. The smallest range of velocities over the hydrological year is experienced in the river by AP4, upstream of the Testwood Mill structures, with a variation of up to 0.5 m/s over winter high flows and summer low lows, from closed and open structures;

10 SAC Annex 1 habitat 3260: Water courses of plain to montane levels with Ranunculion fluitantis and Callitricho- Batrachion vegetation.

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In summary, these results indicate that water velocities in the river are overall optimal to acceptable for Ranunculus growth. At AP1, the reach most affected by the abstraction, water velocity conditions should be optimal for the growth of Ranunculus, for most abstraction and structure settings. The exception to this is the fully licensed abstraction scenario which causes water velocities to fall into the acceptable band at low flows; which is, by definition, still considered to be suitable for Ranunculus growth. At AP4, the reach most affected by the tidal cycle and structures, velocity conditions are acceptable for healthy Ranunculus growth at low flows, except for the scenario of fully licensed abstraction with closed structures which creates suboptimal velocity conditions at very low flows.

7.2.4. Conclusions

The macrophyte surveys conducted on the River Test between Nursling and Testwood Pool has revealed a species rich assemblage. Notwithstanding the survey constraints described, the survey is considered to be appropriate to assess changes in species composition throughout the sub-reach under investigation. The assemblage observed is characteristic of a base rich lowland river system in which a high proportion of the plants recorded are associated with both ponded and slow flowing freshwater habitats: a factor reflected by the low flow scores obtained downstream of the Testwood PWS abstraction. Species indicative of perennial chalk stream flow were recorded within the assemblage, however, they were only found to be a dominant component of the species assemblage in the reaches with a free flowing hydrological character. The changes in plant assemblage structure and species cover values observed on the approach to Testwood Pool are considered to reflect the increased magnitude of effect of impoundment in the lower reaches created by the presence of structures at Testwood Mill. It is also presented that the occurrence of Potamogeton pectinatus (Fennel Pondweed) in the lowermost sub- reaches may also indicate the presence of a chemical gradient associated with the potential input of water saline / nutrient rich water from the Chadney Meadow system. The evidence from the salinity monitoring (see Section 5.1.3) suggest that there is limited evidence for a regular saline incursion to the Great Test: although salt water can push up into Testwood Pool, sea levels are generally below river levels upstream of the structures on the Great Test. Therefore it would seem to be the case that salinity is not a major factor in determining the distribution of P. pectinatus, and that its presence is more likely to be a response to impoundment of flows at the Testwood Pool structures. Downstream of the abstraction the proportion of slow flowing / lentic species increase in abundance on approach to Testwood Pool structures which reflects the increased influence of these structures on flow and the greater magnitude of effect of impoundment in the lower reaches. The backwater effect created by the structures combined with water level fluctuation created by tidal lock-out at Testwood Pool was observed to propagate to a point upstream of the confluence of the River Blackwater and is concomitantly deemed likely to affect on the plant communities observed from Testwood Pool upstream to the sub-reach immediately downstream of the abstraction (DSTW_01), but not above.

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7.3. Aquatic macroinvertebrates

7.3.1. Introduction

This section details the analysis undertaken using the available relevant aquatic macroinvertebrate data in the Lower Test NEP investigation. A review of baseline information is presented in Section 2.4. This section presents the analysis of historical and new information collected as part of the NEP investigation. Before an assessment of the effect of flow changes can be made, a statistical assessment (Section 7.3.2) was undertaken to determine the suitability of the historical macroinvertebrate data collected at Testwood for use in the NEP. Then, the data were analysed to determine what can be inferred about the effect of the Testwood abstraction upon macroinvertebrates (Section 7.3.3).

7.3.2. Statistical assessment

Below is a summary of the statistical assessment that has been undertaken: the full account is presented in Appendix 7.3.1.

7.3.2.1. Need for the initial statistical assessment The reason for the initial statistical assessment was due to the Environment Agency changing its approach to taking macroinvertebrate samples at the Testwood sampling site (see Section 2.4), which created two datasets: „Old‟ Method and „New‟ Method. The purpose of the statistical assessment was to determine whether or not the whole dataset could be used for the NEP investigations i.e. data from both the „Old Method‟ and „New Method‟ together. The two River Test aquatic macroinvertebrate sampling sites under investigation are:  Upstream of Testwood Abstraction (NGR SU 35250 15350, EA site code 90401); and  Downstream of Testwood Abstraction (NRG SU 35350 15300, EA site code 90402). Figure 2.4.1 shows the location of these sites, and Table 7.3.1 provides a summary of the sampling sites and sampling method adopted („Old‟ Method or „New‟ Method) over the period 2002–2011.

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7.3.2.2. Conclusion ANOSIM analysis (Appendix 7.3) has shown there to be a statistically significant difference between samples when grouped as either being taken with the „Old‟ or „New‟ sampling method. In addition, significant seasonal and sampling year influences on the macroinvertebrate communities are also evident, and this is identified as being related to subtle differences in species composition throughout the historical record. Notably, no significant differences have been identified between the Upstream and Downstream samples indicating that the macroinvertebrate communities are less strongly influenced by location than they are by sampling method, season or year of sampling. SIMPER analysis (Appendix 7.3), conducted to see if the change in sampling method is evident in the species flow traits, has identified that the difference between the macroinvertebrate communities sampled using either the „Old‟ or „New‟ method is best described by a higher abundance of a few taxa associated with moderate to fast flow in the „Old‟ method samples. Interestingly, the one species most strongly associated with the „New‟ method samples, Brachycentrus subnubilus, is also associated with moderate to fast flows and is known to be susceptible to changes in macrophyte cover / weed management thus alluding to the potential influence of management practices on the differences observed. Furthermore, there is no evidence to suggest that the change to the „New‟ method has resulted in disproportionate representation of species associated with either rapid or slow flowing conditions as hypothesised. In summary, there is no conclusive evidence to support the theory that the change in sampling method has accounted for significant differences identified and it is, therefore, concluded that whole data record can be use in flow investigations. In all instances it is advisable that any analysis undertaken combining „Old‟ and „New‟ method samples makes reference to the change in sampling method. Should the Environment Agency wish to further investigate the effects of the change in the sampling method, then it is recommended replicate sampling be adopted to provide a direct comparison of methods without the influence of temporal gradients.

7.3.3. Hydroecological assessment

One way to assess the effect of abstraction upon aquatic macroinvertebrate is to derive relationships between aquatic macroinvertebrate data and flow statistics. Work for the River Itchen Sustainability Study to set an ecological flow threshold for the River Itchen focused on the derivation of a relationship between flow statistics and macro invertebrate data. Whether this approach could be applied for the River Test has been assessed with the conclusion that there is insufficient data from the Testwood sampling sites. This is because the work on the River Itchen drew upon approximately 30 years of historic macroinvertebrate data at numerous sites along the river; in comparison, only 9 years of data are currently available for the River Test at Testwood. Given the natural variability expected in macro-invertebrate data over time and in different parts of the river continuum, as discussed above, a large dataset is needed to have confidence that the relationships between biotic scores and flow metrics are robust and appropriate for use as ecological thresholds. As an ecological flow could not be derived, an alternative approach has been undertaken, as detailed in the sections below. Having determined the suitability of the use of the entire historical data set, this section reports on the hydroecological assessment, looking for evidence of flow effect associated with the surface water abstraction that occurs between the Upstream and Downstream sampling sites. This hydroecological assessment uses comparative analysis of biotic scores for the two macroinvertebrate sampling sites for data collected between May 2002 and November 2011.

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7.3.3.2. Observed to Expected (O:E) LIFE ratios In determining if the macroinvertebrate communities are showing signs of flow stress an assessment of O:E LIFE (F) ratios for both sites has been undertaken. Expected LIFE scores were predicted for each of the sites and the individual sample seasons by RIVPACS analysis, the outputs of which are provided as Appendix 7.3.4. Figure 7.3.5 shows that the LIFE O:E ratio is generally higher in the Upstream site than the Downstream site. This stated, if the O:E ratios are reviewed against the proposed Water Framework Directive (WFD) „High‟ O:E threshold of 0.975 then both sites are indicating that flows are of a level able to support High ecological status (Dunbar et al., 2006). If one takes a more precautionary approach and uses an O:E ratio cut-off of 1(to account for potential for under predictions by RIVPACS in southern chalk streams) then flow stress conditions are only encountered infrequently and neither site is currently assessed as being flow stressed.

7.3.3.3. Comparison to Broadlands The River Test is not a free flowing system of habitat continuum and particular sections are particularly affected by impoundment and structures. As such comparison between upstream and downstream reaches offer little direct relevance of hydroecological comparisons. That said, it can still be instructive to compare results from one site to another to generate broad conclusions.

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7.3.3.4. Effect of historic and fully licensed abstraction scenarios The above sections essentially comprise an assessment of the historic abstraction upon macroinvertebrates through the derivation of biotic scores, as the scores reflect conditions in the river at the time of sampling i.e. the historic abstraction. The conclusion from the above analysis shows that there is no evidence of abstraction pressure: although the LIFE scores tend to be lower at the Downstream site they still indicate that flows shaping the macroinvertebrate community throughout the hydrological year are able to support high ecological status. Further, the conservation scores were found to be significantly higher at Testwood than at Broadlands site upstream, indicating that the historic abstraction has a negligible effect as a high quality invertebrate assemblage is present. Assessing the effects of the fully licensed abstraction upon the macroinvertebrates is more difficult to ascertain as there is little evidence upon which to form an assessment and (as stated above) insufficient information with which to derive a relationship between flow statistics and the macroinvertebrate data. Another approach can be to examine the change to the hydrological regime that would be expected under fully licensed abstraction with regard to water velocities. Section 5.2.2 details the effect of simulating different combinations of abstraction and structure settings to isolate and identify the effect of the tidal regime upon water velocities from the different influencing factors. The appropriate location to assess the potential effect of fully licensed flows upon the aquatic macroinvertebrate community is at AP1 only as this is closest to the sampling site and the abstraction intake. The hydraulic model shows that under conditions of no abstraction, there is a progressive downstream reduction of channel velocities in the Lower Test due to the tidal effect and structure settings. Figure 5.2.2m shows the effect of the fully licensed abstraction scenario (closed structures) over 2006 and 2007; the results for 2006 are of key interest as this is the representative very low flow year for the NEP study. It can be seen that the effect of the fully licensed abstraction scenario (closed structures) at AP1 causes water velocities to drop by up to 0.23 m/s during the period of low flows in 2006. This is likely due to the combination of abstraction, low water levels due to the very low conditions, and the high sill level of the broad crested weir affecting water velocities at this location. The effect of the fully licensed abstraction at this time upon water velocity is much lessened at AP2 (reduced by up to −0.09 m/s) and further lessened at AP4 (reduced by up to −0.06 m/s). The magnitude of the reduction in water velocity from fully licensed abstraction (structures closed) could have the potential to affect the macroinvertebrate assemblage by creating unfavourable conditions. However, the significance of this drop in velocity to the macroinvertebrate community is uncertain and may not have any detrimental effects. It should also be noted (Figure 5.2.2e) that the effect of the tide and structure settings (no abstraction) also has a comparable, and even greater effect on water velocities, at different times, and so conditions may not always be favourable for macroinvertebrates at AP1 even under conditions of no abstraction.

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7.3.4. Conclusion

The review of biotic scores has not provided any conclusive evidence of abstraction pressure, and although the LIFE scores tend to be lower at the Downstream site they still indicate that flows shaping the macroinvertebrate community throughout the hydrological year are able to support high ecological status. It is likely that the differences observed between the sampling sites are a result of variability in habitat complexity, with the shallower Upstream site exhibiting flow velocity characteristics that would account for the higher LIFE scores and potentially greater ASPT values. Importantly, this flow assessment is a measure of the macroinvertebrate community response to flow changes at the sampling site scale caused by the Testwood abstraction. It therefore does not necessarily reflect the different physicochemical factors affecting the ecology communities which would be present within the predominant habitat further downstream i.e. slower moving impounded reaches. It should be noted that the macroinvertebrate response at each of the sampling sites is in part dependent on the sensitivity of the habitat to changes in flow, with shallow glide type habitats (Upstream site) typically being more sensitive than deeper gravel runs habitats (Downstream site) (Environment Agency, pers. comm.). In this instance the notable habitat differences between the sites leads to the potential for differences in response to changes in flow, this is likely to compound interpretation of the temporal changes in LIFE scores observed. Furthermore, the potential effects of flow impoundment from the downstream gauging weir and the influence of the Testwood Pool structures limit the validity of hydro-ecological assessment downstream of the abstraction. In summary, comparative analysis of the macroinvertebrate communities of the sampling sites has not identified flow stress arising from historic abstraction. It is concluded that differences in habitat complexity and site sensitivity to changes in flow, combined the influence of impounding structures limits the validity of hydro-ecological investigation downstream of the abstraction. The conclusion therefore is that the effect of the historic Testwood abstraction upon the aquatic macroinvertebrate community is negligible. Assessing the effects of the fully licensed abstraction upon the macroinvertebrates is more difficult to ascertain as there is little evidence upon which to form an assessment and a paucity of data upon which to derive a relationship between flow statistics and the macroinvertebrate data. Therefore an assessment was made by examining the outputs of the hydraulic model with regard to velocity. It can be seen that there is a reduction in water velocity of up 0.23 m/s at AP1 under fully licensed abstraction during very low flows years such as 2006. The spatial extent of this potential significant effect is approximately 145 m in length i.e. it reaches from the abstraction intake to the location of the broad crested weir at Testwood Gauging Station. The frequency when such effects would be experienced is low; the effect seen in 2006 represents the worst case scenario in the study period (see Section 3.5.1). Therefore it can be concluded that there is the potential for the fully licensed abstraction at Testwood to affectmacroinvertebrates upon the 145 m reach downstream of the intake under low lows, however the duration and extent of these occurrences would be small. It should also be noted however that the effect of the tide and structure settings (in a scenario of no abstraction) also has a comparable, and even greater effect on water velocities, at different times, and so conditions may not always be favourable for macroinvertebrates at AP1 even under conditions of no abstraction.

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7.4. Protected species

7.4.1. Otters

Figure 2.5.1 shows the location of otters as recorded using the most recent survey information. As stated in section 2.5.2 otters are unlikely to be directly affected by abstraction although there could be indirect effects should its prey be affected; suffice that a watercourse does not dry up entirely, it is likely there will be little impact on otters (Environment Agency, 2011c). The effect of the abstraction upon flows and water levels as shown in Section 5, and the presence of the MRF flow condition shows that the Testwood abstraction would not cause the river to dry up. The conclusion of Section 6 shows that the abstraction is not having a significant effect upon fisheries. It is concluded that the Testwood PWS abstraction has a negligible effect upon otters, their habitats and prey.

7.4.2. Water voles

Figure 2.5.1 shows the location of water voles as recorded using the most recent survey information. The Environment Agency (2011c, p41) state that, “changes to flow management, drainage practices and water levels are key to maintaining this species. Abstraction is unlikely to be a key factor, unless the impact, even locally, is significant. Any impacts are likely to be mitigated by management of flow into and within floodplain ditches, reversing historic land drainage practices and appropriate water level management and sympathetic land use management.” Section 3 details the hydromorphology of the study reach, noting the artificial bank protection and vegetation strimming that is characteristic of the Great Test; given the heavily modified nature of the main river channel the amount of habitat in the form of burrow-able banks available to water voles is limited. Section 5.2.3 details the effect upon water levels of the Testwood PWS abstraction and the effect of the tidal regime and water level management. As discussed in Section 5.2.3, the response of the Lower Great Test to different abstraction and structure management scenarios reflect a hydrological behaviour more akin to a lacustrine than riverine habitat. The timing and magnitude of water level variations between Testwood Mill and the abstraction confirms that the entire river reach responds broadly as a single water body, rising and falling as inflows or outflows to the reach change. This behaviour is most apparent when comparing long term water level trends at different locations along the study reach. The combined effect of the tidal regime and structure upon water levels can be significant, with water level changes of up to 0.6 m under low flows. From the figures, tables and discussion in Section 5.2.3, it is necessary to screen out the effect of the tidal regime on the model result so that the effect of the abstraction can be considered in isolation as much as possible. Therefore the model output for the closed-structures comprises the best dataset to use. Table 5.2.3b shows that (with closed structures) the effect upon water levels at AP1, just downstream of the abstraction, is a reduction of up to 0.06 m at WL98 under historic abstraction and a reduction of up to 0.14 m at WL98 under the fully licensed scenario (see Section 5.2 and Figure 4.1.1 for the location of the hydraulic model‟s Assessment Points). Table 5.2.3h shows effect at AP4 comprises a reduction in water levels up to

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7.4.2.1. Conclusion As stated previously, the study reach is subject to hydrological changes caused from abstraction and from the effects of the tidal cycle and structure management and so the results from the modelling work require careful interpretation to isolate each of these factors to understand their relative effect. The effect of the natural tidal cycle under conditions of no abstraction has been seen to cause considerable change in water levels within the study reach, with the greatest effect at AP4 and AP2 with a reduced effect at AP1. The Testwood abstraction has a smaller effect upon water levels, with a greater effect at AP1 decreasing downstream to AP4. In conclusion, it is considered that the effect of Testwood abstraction upon water levels would result in a negligible effect on water voles, in terms of its spatial extent, duration and frequency of effects. This is because the magnitude of the effect is small, and much less than the natural tidal fluctuations experienced in the reach. The frequency and duration of the maximum reduction in of water level caused by the abstraction (up to −0.16 m under fully licensed conditions, with closed structures) is small, given the very low flows experienced in 2006 which have been shown to be infrequent, relative to the context of daily tidal impact.

7.4.3. White clawed crayfish

The Environment Agency (2011c, p41) state that, “changes to flow management, drainage practices and water levels are key to maintaining this species. Abstraction is unlikely to be a key factor, unless the effect, even locally, is significant. Any effects are likely to be mitigated by management of flow into and within floodplain ditches, reversing historic land drainage practices and appropriate water level management and sympathetic land use management.” White clawed crayfish prefer flowing water habitats with heterogeneous flow patterns, in which the species can burrow into the banks, and where overhanging banks, boulders and woody debris provide shelter. The potential effect of the Testwood PWS abstraction upon the species is indirect. The potential effect would be a reduction in water levels such that the species becomes vulnerable to predation; that the reduced flow affects the growth of bankside vegetation and submerged plant communities; or any effects upon increase siltation or turbidity.

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7.4.4. Southern Damselfly

As stated in Section 2.5.5, the Environment Agency concluded that Southern Damselfly would not be expected to inhabit the area downstream of the public water supply abstraction intake and therefore no assessment for this species is required for the NEP Investigation.

7.5. Floodplain macroinvertebrates

Section 2.6 presents a summary of the habitat requirements of floodplain invertebrates, which is a large and varied group, as being dominated by vegetation structure and composition, and water levels in the floodplain. There is little information available on the specific water level preferences of floodplain invertebrates however. The potential effect of the Testwood PWS abstraction upon floodplain invertebrates is therefore indirect as it would involve a reduction in water levels such that the in-field water tables in the floodplain or water meadows become such that they are too low to support the required wetland vegetation, or that it causes deleterious changes to the flooding regime. Therefore consideration of the effect of the abstraction upon this faunal group is done by assessing the effect of the abstraction upon water flowing into the network of small channels in the Lower Test Valley, and upon in-field water tables. In order to identify the ways in which freshwater flows influence wetland habitats within the floodplain Section 7.6 discusses the impact flow pathway for the Testwood abstraction, and the sources of water that contribute to the Lower Test Valley SSSI.

7.6. Wetland habitats and species

7.6.1. Introduction

As part of the Testwood NEP investigation, an assessment has been undertaken to assess the effect of the abstraction on the wetland habitats of the Lower Test Valley SSSI. The Lower Test Valley SSSI contains a full transition from saltmarsh to neutral meadows (Section 2.7), and is also of potential value for breeding waders (Section 2.8). This section sets out the results of the Lower Test NEP wetland assessment. There are three questions for the wetland assessment to answer:

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A program of field survey and monitoring, consultation and review of historic reports and data have developed the understanding of the hydrology of the Lower Test Valley SSSI (Section 5). A wetland model has also been constructed to simulate wetland water table levels (see Section 4.1.2). The wetland model developed is based on the Atkins‟ SWaMP (Sustainable WetlAnd Management Planning) Tool that has been used to address similar issues in coastal freshwater wetlands such as the Lower Test Marshes. The physical basis and development of the wetland hydrological model is presented in Appendix 5.2.1.

7.6.2. Impact pathway assessment

Based on the understanding of the hydrology of the Lower Test Valley, the potential effects of the Testwood abstraction on flows and levels in the River Test, and the distribution of different habitats across the site, the following impact pathway is expected from the Testwood abstraction upon wetland habitats and species:  Abstraction from the river reduces water levels in the River Test downstream of the Testwood abstraction;  The effect on river levels extends downstream to structures that allow water to flow out of the river channel and onto the floodplain;  Changes in river levels affect the flows over structures that connect the river and ditches and watercourses on Lower Test Valley SSSI;  The reduction in flows through the sluices leads to a reduction in floodplain ditch water levels;  Reductions in ditch water levels are transmitted to communities inhabiting watercourses or via water table changes to influencing meadow habitats; and  Effect of changes in the water level regime result in a change beyond the requirements of the target habitats. It is important to note that in general, the current connectivity between the River Test and the Lower Test Valley SSSI is limited. The flow pathways are shown in Figure 7.6.1. For example, water in the northern half of the Lower Test Valley, including part of the SSSI and the whole area known as Manor Farm, is fed from Nursling Fish Farm (Structure 1457) and/or Conagar Bridge (Structure 1458) (see Figure 3.7.7). The flow pathway is that shown by the yellow line shown on Figure 7.6.1. The area of influence of the Conagar / Nursling feed is extensive and is a factor of the historic management of the Lower Test Valley as water meadows. However, available data suggest that there has been a significant reduction in the water flowing across the Manor Farm meadows from Nursling Mill (see Section 3.7) as the historic meadow distribution network has become defunct and river managers have increasingly maintained water within the main river channels for fisheries purposes (see Section 3.8.2). In addition, most of the southern half of the SSSI area is tidally dominated (the tidal flow pathway is shown as a blue line on Figure 7.6.1). This part of the Lower Test Valley SSSI is dominated by species-poor inundation grasslands (MG11), reedbeds (S4) and brackish swamp (S5 and S6) habitats. All these habitats are associated with regular and prolonged flooding by fresh or brackish water, features of the hydrological regime during high flow rather than low flow conditions.

7.6.2.1. Spatial extent The main part of the floodplain that is connected to the River Test downstream of the Testwood abstraction is eastwards of Structure 1417 that connects the Great Test to the Middle Test. This flow path is shown by a

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7.6.2.2. Temporal factors The impact pathway is only operational at low tide: at high tide, water levels in the Middle Test and in the fields and ditches adjacent to it will vary in response to tidal fluctuations, not freshwater flows out of the Great Test. In addition, the higher the tide, the higher the water levels in the Great Test (due to the backing up or impoundment of water through the structures at Testwood Mill) so that higher tides actually lead to more freshwater discharge over the Middle Test structure. Figure 7.6.3 shows the flows of water through Structure 1417 into the Middle Test under the current (historic) and fully-licensed scenarios, as well as various sluice settings at Testwood Mill. Changes in the rate of abstraction from historic to full-licensed will not affect the timing of freshwater flows into the Middle Test (Figure 7.6.3a). The largest potential risk to the duration and magnitude of freshwater flows over Structure 1417 would appear to be the operation of sluices at Testwood Mill downstream, where changing settings from partially open to fully open results in a large reduction in the duration of freshwater flows over the structure. This is partly evidenced in the water level monitoring data shown in Figure 5.1.7, where increased sluice operation, due to higher flows in the Great Test from November onwards, causes significantly greater fluctuations in the water levels in the Middle Test during low tide periods.

7.6.3. The potential effect on wetland hydrology

7.6.3.1. Water balance The wetland model for the Lower Test Valley has been used to quantify the field-scale water balance in order to provide an initial view of the likely effects of the area from the Testwood abstraction. The impact pathway assessment has shown that the main route for the transmission of the abstraction effect is via changes in ditch water levels, mainly in the Middle Test. Consequently, the significance of lateral exchange between the ditch and field can be used as an initial measure of the magnitude of effects. Figure 7.6.5a shows the monthly water balance for a location 25 m away from a ditch or adjacent channel; Figure 7.6.5b and 7.6.5c show the monthly water balance for locations 50 and 125 m from a watercourse respectively, broadly equivalent to the distance between the River Test and the centre of Field A in Figure

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7.6.3.2. Water level requirements of key habitats Figure 7.6.2 takes a more detailed view of the distribution of habitat communities within the potential impact pathway. Table 7.6.1 reviews the main characteristics and available ecological threshold data for habitats identified. Ecological threshold data have been obtained from a variety of literature sources as follows:  A publication entitled the „Ecohydrological Guidelines for Lowland Wetland Plant Communities‟ (Wheeler et al., 2004) provided a series of user-friendly, generic ecohydrological information on the requirements of selected wetland communities. The guidelines were developed for and assisted with tasks such as Appropriate Assessments of the effects of Agency permissions and consents required under the Habitats Directive Review of Consents. The ecohydrological (also known as hydroecological) guidelines summarise the water level requirements of vegetation communities using a colour coded suitability chart showing the position of the water table below ground surface over the months of the year. The green region is the “preferred” hydrological regime, whereas the amber region represents a zone which is “tolerable for limited periods” and into which measured water tables may fall in a particular year during wetter or drier than average periods. Such conditions appear to have no adverse effect on the community providing they do not occur consistently year on year. However, if a mean value, based on three consecutive readings each at least 14 days apart, falls within the red zone there is a high likelihood that the composition of the community will be affected;  A long list of species-specific, and generic water level thresholds have been provided in an English Nature Report by Newbold and Mountford (1997). This document sets out the upper and lower limits of tolerance to either soil water tables or depths;  Wheeler et al. (2009) have provided a review of ecological, hydrological and hydrogeological data at over 200 wetland sites (including over 1,500 stand samples) to determine the water level regimes that characterise some of the most distinctive wetland habitats in the UK; and  For wet woodland communities, a Natural England report entitled „Ecohydrological guidelines for Wet Woodland‟ (Barsoum et al., 2005) provides some water level maxima, minima and ranges. The following points summarise how the different water level threshold data available have been applied as part of the Lower Test Valley SSSI assessment:  On the Lower Test Valley SSSI, habitat surveys have shown that MG8 and M22 occur in association. As a result the detailed water level requirement data provided by Wheeler et al., (2004) for MG8 Cynosurus cristatus – Caltha palustris have been taken as representative for both communities.  For the W6 Alnus glutinosa – Urtica dioica wet woodland community the water level ranges set out in Barsoum et al., (2005) have been used.

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Overall, the ecological thresholds given in the literature for different habitat types along the potential impact pathway (MG8, MG11, S5, W6 and M22) corresponded closely with the minimum water level requirements of MG8 (see Table 7.6.1). Indeed, water level minima for MG8 provided a precautionary estimate for the water level requirements of all the other habitat types considered (see Table 7.6.1) indicating that MG8 water level requirements could be used as a surrogate for habitats throughout the Lower Test Valley SSSI. Figure 7.6.4 shows the range of water tables for the MG8 community, presenting “preferred” depths (green) and those water tables depths that are “tolerable for limited periods” (amber), and the zone (red) which may incur deleterious effects if water tables are held at this depth. For other habitats, the range of ecological thresholds identified in the literature are shown in Figure 7.6.4. Throughout the entire assessment period both current water levels and those predicted to occur under fully licensed conditions were within the maximum and minimum thresholds for the full range of communities present in the Lower Test Valley SSSI potential impact area.

Table 7.6.1 Water table depths for Lower Test wetland habitats

Water table depth from the Community Description surface Source Winter Summer MG8 Cynosurus Deliberately flooded in past for long Wheeler et al. cristatus – Caltha period in winter and spring. Constantly −0.05 m -0.5 m (2004) palustris grassland damp soils MG11 Festuca rubra – Inundation grasslands frequently Newbold and Agrostis stolonifera – flooded by fresh or brackish water but 0 m −0.4 m Mountford (1997) Potentilla anserinea* also prone to drying out Mire grassland derived from rich fens on M22* Juncus moist sites that have been ditches and Newbold and subnodulosus* – +0.3 m −0.4 m mown, often flooded in winter. Soils Mountford (1997 Cirsium palustre moist to damp for most of the year. Regularly very prolonged winter S5 Glyceria maxima flooding, usually in waterlogged sites Wheeler et al. −0.03 m −0.7 m swamp with water at soil surface for most of the (2004) summer S7 Carex acutiformis In wet hollws within flood meadows. Newbold and +0.5 m −0.4 m swamp Continuously waterlogged sites Mountford (1997) Found on wet, nutrient-rich soils e.g. W6 A. glutinosa–Urtica shallow banks along brook meanders −0.05 to Barsoum et al., −0.05 m dioica that receive a lot of sediment-rich winter −0.45 m (2005) flood water

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This section considers the extent to which existing water levels in the Lower Test Valley SSSI might be influenced by potential water level changes under different abstraction scenarios. For this purpose the wetland model has been run under three separate abstraction scenarios (naturalised, historic and fully-licensed) with sluices partially open. For each scenario, water levels predicted by the hydraulic model have been used as a boundary condition for the wetland model. The water level boundaries used are shown in Figure 7.6.6a. Water tables resulting from different abstraction regimes/scenarios have been linked to the water level requirement data set out in Figure 7.6.4 to assess the likely ecological significance of any water level changes in the Lower Test. In each scenario, only river levels were changed in order to isolate, and therefore identify, the effects of abstraction from other factors. Rainfall and ET were maintained at the measured daily rates (precipitation from the Romsey rain gauge and evaporation from MORECS data) in each scenario, and a constant value of groundwater levels of 2.5 m OD was applied (see Appendix 4.1.1). Figure 7.6.5b compares the water table levels for 2011 under the naturalised, historic and fully-licensed scenarios relative to the water level requirements of MG8. Results show that the water table in the Lower Test Valley SSSI is largely disconnected from adjacent watercourses, presumably due to the low prevailing conductivity of the silty clay soils. Water table levels vary little due to changes in watercourse levels; the only differences between predicted water table levels in the scenarios were differences in the region of 0.01 m in late summer. At other times, water table levels for different scenarios were equivalent highlighting the dominance of precipitation, evaporation and gravel water levels in determining wetland water levels across wetland habitats of the Lower Test Valley Marshes SSSI. It is therefore concluded that the Testwood PWS abstraction has a negligible effect upon wetland habitats in the Test valley. It is also therefore concluded that the Testwood PWS abstraction has a negligible effect upon floodplain macroinvertebrates (See Section 7.5).

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Table 7.6.2 Requirements of wet grassland plant communities

NVC Classification Dominant species Occurrence (habitat) Soil type Water table Usually found on floodplains in river valleys. Less than 500ha of this habitat type thought to remain in the UK. In the Typically on well-structured South of England it is usually reliant on managed Substantial lateral water movement alluvial soils over gravel or chalk Water Meadows: hydrological systems based on a dense ditch network, such facilitates subsurface drainage in or on permeable organic soils Crested dog‟s tail Crested dog‟s tail Cynosurus cristatus – as in water meadows. An important landscape feature for winter and sub-irrigation in summer. with high porosity and high and marsh-marigold marsh-marigold Caltha palustris the flat lowland sites in southern England is the presence of Soils with water tables usually within available water capacities. High grassland (MG8) artificial surface drainage systems, designed to remove 0.5 m of the surface and showing permeability is the major factor surface water swiftly from the site. The drainage system relatively little seasonal fluctuation. uniting MG8 soils. typically comprises shallow features connecting to deeper ditches, which then join the main river downstream. Ordinary damp Common from the lowlands into the upland fringe of Gleyed brown earths and Solis permanently damp due to meadows: Creeping bent (Agrostis stolonifera), Yorkshire- England, in pastures and derelict farmland. This was alluvial soils – neutral to slightly ground or surface water. Not Yorkshire-fog and fog, soft-rush (Juncus effusus) and creeping perhaps the most common community in the drained acid. In more calcareous sites, normally found in areas subject to soft-rush rush- buttercup (Ranunculus repens). grassland areas of the Fens. Ordinary damp meadow hard-rush may replace the soft- flooding. pasture (MG10) pasture found in areas with permanently high water table. rush. Inundation Brown earths and alluvial soils Summer water levels should be 0.1– grassland: red Probably frequent especially in west) in flood plains, upper (sand and shingle possess 0.5 m below ground. Frequently Creeping bent, red fescue and silverweed fescue, creeping saltmarsh and marginal habitats (i.e. by ditches, ponds and particular variants). flooded in winter, maximum winter (Potentilla anserina). bent and silverweed shores). Common on the silt fringe of the Fen basins. Circumneutral but often water levels should be at or very grassland (MG11) brackish. near ground surface. Marsh thistle (Cirsium palustre), marsh Often flooded in winter. Water levels horsetail (Equisetum palustris), meadowsweet monitoring indicates maximum water Rich-fen meadows: On neutral to rather alkaline (Filipendula ulmaria), Yorkshire-fog (Holcus Occasional in central and eastern England, where rich fens levels at or very near the ground blunt-flowered rush soils (pH 6–8) often peaty but lanatus), blunt-flowered rush (Juncus have undergone some reclamation. surface, with mean water levels 0.14 and marsh thistle also on alluvium and base-rich subnodulosus), greater bird's-foot-trefoil (Lotus More common the Fen basin than it is today. m below the ground surface, and fen-meadow (M22). clays. pendunculatus), water mint (Mentha minimum water levels 0.43 m below aquaticum) and moss Calliergon cuspidatum. the ground Nutrient-rich, circumneutral or Washland: reed Usually in waterlogged siteswith Regularly inundated flood-plain wash-land (also common as basic alluvium, or organic soil sweet-grass swamp Reed sweet-grass (Glyceria maxima). water at soil surface for most of the a fringing swamp to still or sluggish eutrophic water). with regular inputs of mineral- (S5) summer. rich water (pH>6.0). Tall sedge Mesotrophic to eutrophic, meadows: great Wet hollows within flood meadows (also common dominant Continuously waterlogged sites (up Great pond-sedge (Carex riparia). circumneutral mineral soils, pond-sedge swamp of swamp by still or sluggish, often eutrophic, water). to 20 cm of water). rarely on peat (pH 5.8–7.0). (S6) Tall sedge Moderately eutrophic, meadows: lesser Wet hollows within flood meadows (also a dominant of Continuously waterlogged sites (up Lesser pond-sedge (Carex acutiformis). circumneutral to basic mineral pond-sedge swamp swamp by still or sluggish, often calcareous, water). to 20 cm of water). soils (pH 6.0–6.8). (S7) Soil inundation should not last longer Broadleaved, mixed than 40% of the growing season with and yew woodland Alder (Alnus glutinosa) – nettle (Urtica dioica) Typically occurring in floodplain mires Silt summer water levels 0.5 m below the (W6) ground. Definition of terms 1. The use of the terms 'dry', 'moist', 'damp' and 'wet' follows that defined by the water indicator (F) values of Ellenberg (1988), i.e. occurrence in the gradient from dry shallow-soil, rocky slopes to marshy ground, and then from shallow to deep water. 2. 'Dominant' adapted from use in the description in the National Vegetation Classification (Rodwell 1991, 1992, 1995): i.e. species which occur in the majority of samples, but with ground cover in excess of 5 per cent and which also form a major part of the vegetation cover in at least some examples of that community. Source: modified from Newbold and Mountford, 1997

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7.7. Breeding waders and passerines

The potential effects of abstraction on breeding waders and passerines has been evaluated based on an assessment of the current and historic status and distribution of the main species (Section 2.8), an assessment of the of the hydrology of the site (Section 3) and a review of the potential impact pathway between the abstraction and the preferred habitat of the target species (Section 7.6.2). The impact pathway between the Testwood abstraction and breeding waders and passerines in the lower Test Valley is equivalent to that described for wetland habitats and species. Only a limited part of the Lower Test Valley SSSI is connected to the River Test downstream of the Testwood abstraction (within the potential area of influence of the abstraction) as shown on Figure 2.8.1. Historic areas of breeding wader habitat lie outside this potential „area of influence‟; the location of both fields suggests that historic breeding wader habitat is closely linked to historic management of the meadow systems specifically sluice operation at Nursling Mill and Conegar Bridge, and flows in the Test Back Carrier. Indeed, the timing of changes in the status of breeding waders (Section 2.8) corresponds closely with reductions in flows into the meadows (Section 3.7.1.2). It is concluded that the Testwood PWS abstraction has a negligible effect upon breeding waders and passerines.

7.8. Intertidal habitats

The Habitats Directive Stage 3 and 4 assessments considered the potential effects of fully licensed rates of abstraction at Testwood on all intertidal features associated with the Solent and Southampton Water SPA and concluded no adverse impact. The conclusions of the Habitats Directive assessment have been used within this Lower Test NEP study for the effect of the Testwood PWS upon intertidal habitats.

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8.1. Introduction

The NEP study has built on the previous work undertaken by the Environment Agency set out in its Baseline Data Report (2011c) and its initial review of the Testwood abstraction entitled “Testwood Public Water Supply Abstraction Impact Investigation – Statement of Issues and Assessment” (2010a). The NEP Investigation commenced with the development by Atkins/Southern Water of a Scoping Report which was approved by the EA and Natural England in May 2011. The study has involved the collation and intensive analysis of a very significant volume of hydrological and ecological data, focusing on the specific range of issues identified by the EA. Additional data have also been acquired through field studies on the Lower Test and a series of models to process and analyse these data have been developed as follows:  An Infoworks Hydraulic Model of the Great Test downstream of the Testwood abstraction – this has allowed a much better understanding of how river flows (under different abstraction scenarios), the structures at Testwood Pool and the tide affect water levels and velocities in the reach between the abstraction and Testwood Pool.  A Wetland Model of the Lower Test Valley SSSI – outputs from the hydraulic model have been used with this model to evaluate the potential effect of flows (and thus different abstraction scenarios) in the Great Test on water table fluctuations in the SSSI.  A Thermal Model of the Great Test downstream of the Testwood abstraction – this has allowed a much clearer understanding of how river flows (under different abstraction scenarios) might affect the temperature regime of the river under various climatic conditions.  A Salmon Movement Model – this work, undertaken by Pisces Conservation Ltd in consultation with Dr David Solomon (Independent Fisheries Consultant) and Dr Adrian Fewings (EA Fisheries Specialist), has sought to develop a model that simulates the effect of river flows and temperatures on the timing and magnitude of upstream migration of salmon past the Nursling fish counter on the Great Test. The model draws on the extensive data obtained from the Nursling counter between 1996 and 2008.

8.1.1. Confidence in Raw Data and Model Outputs

8.1.1.1. Raw Data There is generally a high degree of confidence in the physical data used in this study, given that most data are obtained by direct measurement without the need for significant processing and interpretation. This includes:  Channel cross-sections;  Dimensions of structures;  Flow data – some infilling has been required and some channel inflows and outflows have required informed estimates (e.g. the abstraction at Nursling Fish Farm) but the data set is generally considered to be comprehensive and fit for purpose;  Water temperature – although adequate for this assessment, some structured long-term monitoring at several locations on the Lower Test (Great and Little Test) and in the estuary would be desirable for future assessments.

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8.1.1.2. Model Outputs Based on the input data, calibration, reliability and purpose (i.e. use for which the output data are required), the degree of confidence that can reasonably be placed in the output data can be summarised as follows:  Infoworks Hydraulic Model – High confidence  Wetland Model – Medium to High confidence  Thermal Model – High confidence  The Salmon Movement Model has proved to be a useful means of testing various conceptual models relating to the factors underlying the observed patterns of salmon movement. It is not suitable for use as a quantitative modelling tool.

8.2. Conclusions regarding the Testwood Abstraction

8.2.1. Components of the abstraction to be considered

There are three flow regimes arising from the Testwood abstraction that need to be evaluated in this NEP Investigation. They are:  Current or historical use of the licence – this is significantly less than the full licensed abstraction and thus gives rise to correspondingly higher flows downstream of the intake than would occur if the full licence were being abstracted; the relationships and trends associated with the available ecological data are all set within the context of the current or historical abstraction.  Full licensed abstraction – since the full licence has never been abstracted on a sustained basis, even for relatively short periods of time, this also requires extrapolation of the hydro-ecological relationships and understanding that has been determined for the assessment of the current/historical use of the licence. In addition to the above, the Minimum Residual Flow Condition (MRF) has also been considered where appropriate. Table 8.1 summarises the conclusions regarding the Testwood abstraction upon physical aspects of the River, and Table 8.2 summarises the conclusions regarding the ecological aspects.

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As discussed in Section 6, the EA has identified four “environmental objectives” for the protection of adult salmon in the Lower Test. These are: 1. A flow regime in the lower River Test that maintains or improves passage for migrating salmon; 2. The effective screening of all abstraction intakes to prevent fish being drawn in and trapped at any stage of their life cycle; 3. The maintenance of a water temperature profile in the lower River Test which is not raised as a result of increased abstraction and is as resilient as possible to climate change; 4. A flow regime that maintains or improves water quality in the River Test for salmonid populations. With regard to Environmental Objective 2, the planned improvements at Testwood will address the issue of intake screening directly and ensure that all screens comply with the latest EA standards. With regard to Environmental Objective 4, the EA acknowledged in its “Issues and Assessment” Report that the Testwood abstraction does not present a material risk with regard to water quality concerns. With respect to the Testwood abstraction, therefore, this objective has been met. This leaves Environmental Objectives 1 and 3 as the primary focus of the conclusions below. In addressing these objectives, the following assessments have been undertaken:  An assessment of the general migratory of salmon in southern chalk stream rivers;  A review of historical changes in salmon catches and the relationship between their distribution in the Lower Test and river flows and temperatures;  An assessment of the EA‟s Returning Stock data and its relationship with river flows in the Lower Test;  A detailed review of the available fish counter data on an annual and sub-annual basis;  An evaluation of how representative the 1996–2010 period (the period for which fish counter data are available) is with regard to low flows and warm summers;  Consideration of how significant the proportion of fish that return to the estuary but never enter the river might be in warm, low flow summers;  A review of the general pattern of salmon migration up the Great and Little Test and the degree to which the proportion of early (summer) running to late (autumn) running fish was influenced by river flows or water temperatures;  An assessment of the most likely temporal profile of arrival of fish in the estuary and thus development of an understanding of the extent to which fish delay migration upstream following their arrival;  Using the above, development of a conceptual model of salmon arrival and delay which then formed the basis for developing a statistical model of salmon arrival and their movement up the Great Test under the influence of river flows and temperature;  Use of the hydraulic model to understand the hydraulic regime (flow, velocity, water depth) that a fish would experience under different flow regimes at various in the reach between the Testwood abstraction and the tidal limit at Testwood Pool;  Development and use of a thermal model of the same reach to evaluate how different flow regimes might give rise to a changes in the thermal profile of the river downstream of the abstraction;  Consideration of the range in temperature regime that salmon will experience in the River Test from day to day (diurnal variation), within a given summer/autumn season, and from year to year. This also extended to an evaluation of the thermal regime of the River Test compared with neighbouring salmon chalk rivers (the River Itchen and the Hampshire Avon).

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8.2.2.1. Environmental Objective 1: The Testwood abstraction must support a flow regime in the lower River Test that maintains or improves passage for migrating salmon The conclusion of this assessment is that the Testwood abstraction is highly unlikely to hinder the passage of salmon upstream, even in very low flow periods that extend below those observed historically. A similar conclusion is drawn with regard to the impact of the impoundments at Testwood Mill.

The main points underlying this conclusion are as follows: 1. The reach downstream of the abstraction is naturally tidal – modelling of the complex interaction between the tides, the structures at Testwood Mill and river flows strongly suggests that abstraction at Testwood would not hinder the passage of migrating fish. The nature of the flow regime is such that this conclusion extends to flows as low as the MRF defined in the Testwood licence. Furthermore, the channel surveys and hydraulic modelling have demonstrated that the flow regime in the reach downstream of the Testwood intake but upstream of the confluence with the Blackwater will support the passage of migrating salmon under extreme low flows such as the MRF. 2. Following their arrival in the lower reaches of the river between June and early August, most salmon (70%) do not move upstream until the autumn until they are ready to spawn – there is good evidence that this pattern is a characteristic of the salmon population and that the magnitude of river flows in the Great Test would make little difference. This evidence includes the following: i) The pattern is consistent on both the Great and Little Test. ii) The pattern is consistent in high and low flow years. iii) There are many occasions when salmon are observed moving upstream in the autumn under flow events and/or conditions that would see few if any salmon moving upstream in the summer. The data do not suggest that higher flows in the river give rise to greater migration in the summer – this is perhaps not surprising given the insensitivity of the flow regime upstream of Testwood Pool to changes in flow. iv) Autumn rainfall events are associated with the most significant numbers of salmon moving upstream. Thus, even in the autumn, medium to high flows may be associated with only limited numbers of salmon moving upstream if there has been no rainfall in the previous few days. Conversely, an autumn rainfall event at low flows will often see significant numbers of salmon move upstream. v) The importance of rainfall suggests that some kind of olfactory response may be a primary trigger in the autumn migration upstream. vi) The salmon movement model developed as part of this study over-estimates salmon migration in the summer months if simulations are based on flow functions alone. It is only when a function representing a behavioural characteristic of the salmon (a “willingness to move” function) that the simulations started to represent the observed data more closely. 3. The majority of salmon (65%) move up the Great Test rather than the Little Test

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8.2.2.2. Environmental Objective 3: The Testwood abstraction must support a water temperature profile in the lower River Test which is not raised as a result of increased abstraction and is as resilient as possible to climate change It is important to note in this context that any reduction in river flow will lead to an increase in daytime temperature, however small. As with all other assessments of this nature, therefore, the criterion applied here is whether the rise in temperature caused by abstraction constitutes a significant risk to the salmon or sea trout population in the Lower Test (sea trout may be more sensitive to high temperature than salmon). The conclusion of this assessment is that the Testwood abstraction would not cause a significant rise in temperatures, even under low flow conditions in warm summers. The use of the thermal model to evaluate the temperature regime under extreme low flows also suggests that the abstraction will not compromise the resilience of the lower Great Test to climate change.

These conclusions are primarily derived from the use of a thermal model to test various flow scenarios on the Great Test downstream of the Testwood abstraction under a range of climatic conditions. The key elements underlying the conclusions are: 1. The dominant determinant of water temperatures is the prevailing climatic conditions – temperatures in a cool summer such as 2008 would be 2–4 ºC cooler than a very warm year such as 2006 based on the same flow regime. 2. Differences due to changes in river flows are marginal by comparison – with continuous abstraction at full licensed quantities in the very warm low flow year of 2006, the average increase in temperatures in July due to the abstraction was 0.08 ºC. The maximum hourly difference due to abstraction was predicted to be 0.4 ºC in mid-afternoon in early September when river flows were at their lowest. 3. Potential cumulative effects are negligible – consideration of the cumulative effects of small changes in temperature over several months for a salmon resting up downstream of the abstraction suggested that the cumulative difference in temperature would be almost negligible compared with the equivalent differences experienced by salmon from one year to the next on the River Test or on other rivers such as the Itchen and Hampshire Avon, both of which are generally warmer than the Test. 4. Using temperature in the salmon movement model to constrain salmon migration did not work well – this suggested that the temperature regime on the Great Test is not a major factor in the movement of salmon upstream.

8.2.2.3. Further Monitoring Whilst the risks associated with the Testwood abstraction to salmon remaining downstream are low, the relative scarcity of data regarding salmon behaviour in the lower river and/or estuary would benefit from additional monitoring and review over the next 5–10 years, alongside the ongoing maintenance and improvement of the fish counters and improved monitoring of tidal and water temperature regime.

8.2.3. Sea Trout

There are far more extensive data available regarding the movement of salmon in the Lower Test than for sea trout. However, in regard to the relationship between the flow regime and migratory passage for salmon, it is reasonable to apply the same conclusions. This accords with the approach suggested by the EA in its “Issues and Assessment Report and is summarised in Table 1.2.1. Although sea trout are thought to be as sensitive, if not more so, to high water temperatures than salmon, it is important to note that the assessment of the effects of full licensed abstraction at low flows indicates that in this regard the risks posed by the Testwood abstraction to sea trout in the lower Great Test are very low.

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8.2.4. Aquatic macrophytes

The macrophyte surveys conducted on the River Test between Nursling and Testwood Pool has revealed a species rich assemblage which is characteristic of a base rich lowland river system in which a high proportion of the plants recorded are associated with both ponded and slow flowing freshwater habitats: a factor reflected by the low scores for flow obtained downstream of the Testwood PWS abstraction. Species indicative of perennial chalk stream flow were recorded within the assemblage, however, they were only found to be a dominant component of the species assemblage in the reaches with a free flowing hydrological character. The changes in plant assemblage structure and species cover values observed on the approach to Testwood Pool are considered to reflect the increased magnitude of effect of impoundment in the lower reaches created by the presence of structures at Testwood Mill. Examination of the output of the hydraulic model, with regard to the preferred velocity bands for Ranunculus show that under historic abstraction, velocities are mostly optimal to acceptable for Ranunculus all along the study reach. Under the fully licensed abstraction scenario, velocities are also optimal to acceptable for Ranunculus in most of the study reach; however, at very low flows, velocities become sub-optimal at the end of the study reach due to the combined effects of the water level control structures, the effect of the tidal regime and the abstraction. Whilst flow score investigations and assessment against suggested abstraction guidelines can be useful in assessing the effect of flow reduction arising from surface water abstractions, in this instance it is considered that the effect of the alterations to the channel that have rendered it heavily modified from a Water Framework Directive perspective, and the backwater effect of the structures at Testwood Pool on the river flow character are of a magnitude that will mask any changes in plant community composition that could be attributed to the abstraction of water alone. The conclusion of the assessment is that the historic Testwood abstraction poses a negligible risk to the aquatic macrophyte community. For fully licensed abstraction, the risk is considered to be low, given the potential to create sub-optimal velocities for Ranunculus at very low flow when combined with other factors.

8.2.5. Aquatic macroinvertebrates

The review of biotic scores has not provided any conclusive evidence of abstraction pressure, and although the LIFE scores tend to be lower at the downstream site, they still indicate that flows, shaping the macroinvertebrate community throughout the hydrological year, are able to support high ecological status. It should be noted that the macroinvertebrate response at each of the sampling sites is in part dependent on the sensitivity of the habitat to changes in flow, with shallow glide type habitats (upstream site) typically being more sensitive than deeper gravel runs habitats (downstream site). In this instance the notable habitat differences between the sites leads to the potential for differences in response to changes in flow, this is likely to compound interpretation of the temporal changes in LIFE scores observed. Furthermore, the potential effects of flow impoundment from the downstream gauging weir and the influence of the Testwood Pool structures limit the validity of hydro-ecological assessment downstream of the abstraction. In summary, comparative analysis of the macroinvertebrate communities of the sampling sites has not identified flow stress arising from historic Testwood abstraction. Further, the conservation scores were found to be significantly higher at Testwood than at Broadlands site upstream, indicating that the historic abstraction has a negligible effect as a high quality invertebrate assemblage is present. The conclusion therefore is that the effect of the historic Testwood abstraction upon the aquatic macroinvertebrate community is negligible. Assessing the effects of the fully licensed abstraction upon the macroinvertebrates is more difficult to ascertain: one way to do this is to derive correlations between aquatic macroinvertebrate data and flow

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8.2.6. Otters

As stated in section 2.5.2 otters are unlikely to be directly affected by abstraction although there could be indirect effects should its prey be affected; suffice that a watercourse does not dry up entirely, it is likely there will be little effect on otters (Environment Agency, 2011c). The effect of the abstraction upon flows and water levels as shown in Section 5, and the presence of the MRF flow condition, shows that the Testwood abstraction would not cause the river to dry up. The conclusion of Section 6 shows that the abstraction is not having a significant effect upon fisheries. It is concluded that the Testwood PWS abstraction has a negligible effect upon otters, their habitats and prey.

8.2.7. Water voles

As stated previously, the study reach is subject to hydrological changes caused from abstraction and from the effects of the tidal cycle and structure management and so the results from the hydraulic model require careful interpretation to isolate each of these factors to understand their relative effect. The effect of the natural tidal cycle under conditions of no abstraction has been seen to cause considerable change in water levels within the study reach, with the greatest effect at AP4 and AP2 with a reduced effect at AP1. The Testwood abstraction has a smaller effect upon water levels, with a greater effect at AP1 decreasing downstream to AP4. In conclusion, it is considered that the effect of Testwood abstraction upon water levels would result in a negligible effect on water voles, in terms of its spatial extent, duration and frequency of effects. This is because the magnitude of the effect is small, and much less than the natural tidal fluctuations experienced in the reach. The frequency and duration of the maximum reduction in of water level caused by the abstraction (up to −0.16 m under fully licensed conditions, with closed structures) is small, given the very low flows experienced in 2006 which have been shown to be infrequent, relative to the context of daily tidal impact.

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White clawed crayfish prefer flowing water habitats with heterogeneous flow patterns, in which the species can burrow into the banks, and where overhanging banks, boulders and woody debris provide shelter. Given the heavily modified nature of the main river channel the amount of suitable habitat is very limited. The effect of the abstraction upon water levels is considered to be relatively small, less than the effect of the tidal cycle and structure management, and such that would not cause water levels to become excessively low. Further, water turbidity and sedimentation within the reach downstream of the abstraction is likely to be caused by the inputs from the Blackwater and also from structure management causing water velocities to drop. It is therefore concluded that the Testwood PWS abstraction has a negligible effect upon White Clawed Crayfish.

8.2.9. Southern Damselfly

8.2.10. Floodplain macroinvertebrates

The potential effect of the Testwood PWS abstraction upon floodplain invertebrates is indirect as it would involve a reduction in water levels such that the in-field water tables in the floodplain or water meadows become such that they are too low to support the required wetland vegetation, or that it causes deleterious changes to the flooding regime. Consideration of the effect of the abstraction upon this faunal group has been done by assessing the effect of the abstraction upon water flowing into the network of small channels in the Lower Test Valley, and upon in-field water tables of wetland habitats. The conclusion for wetland habitats (Section 8.2.1.1) is also relevant to floodplain invertebrates, which is that the Testwood PWS abstraction has a negligible effect.

8.2.11. Wetland habitats and species

The extent to which existing water levels in the Lower Test Valley SSSI might be influenced by the abstraction has been assessed using a wetland model to simulate in-field water tables. The model outputs for the different abstraction regimes/scenarios have been linked to wetland hydroecological requirements to assess the likely ecological significance of any water level changes in the Lower Test. The results show that the water table in the Lower Test Valley SSSI is largely disconnected from adjacent watercourses, presumably due to the low prevailing conductivity of the silty clay soils. Water table levels vary little due to changes in watercourse levels; the only differences between predicted water table levels in the scenarios were differences in the region of 0.01 m in late summer. At other times, water table levels for different scenarios were equivalent highlighting the dominance of precipitation, evaporation and gravel water levels in determining wetland water levels across wetland habitats of the Lower Test Valley Marshes SSSI. It is therefore concluded that the Testwood PWS abstraction has a negligible effect upon wetland habitats in the Test valley. The NEP investigation has highlighted that the connectivity between the River Test and the Lower Test Valley is limited. For example, water in the northern half of the Lower Test Valley, including part of the SSSI and the whole area known as Manor Farm, is fed from Nursling Fish Farm (Structure 1457) and/or Conagar Bridge (Structure 1458). The part of the floodplain that is connected to the River Test downstream of the Testwood abstraction is the Middle Test via Structure 1417, whose channel is strongly influenced by tidal fluctuations. Therefore the Test Valley SSSI is influenced by the settings of these structures and the tidal regime.

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The potential effects of abstraction on breeding waders and passerines has been evaluated based on an assessment of the current and historic status and distribution of the main species, an assessment of the hydrology of the site and a review of the potential impact pathway between the abstraction and the preferred habitat of the target species. The impact pathway between the Testwood abstraction and breeding waders and passerines in the lower Test Valley is equivalent to that described for wetland habitats and species. Only a limited part of the Lower Test Valley SSSI is connected to the River Test downstream of the Testwood abstraction (within the potential area of influence of the abstraction). Historic areas of breeding wader habitat lie outside this potential „area of influence‟; the location of both fields suggests that historic breeding wader habitat is closely linked to historic management of the meadow systems specifically sluice operation at Nursling Mill and Conegar Bridge, and flows in the Test Back Carrier. Indeed, the timing of changes in the status of breeding waders corresponds closely with reductions in flows into the meadows. It is concluded that the Testwood PWS abstraction has a negligible effect upon breeding waders and passerines.

8.2.13. Intertidal habitats

The Habitats Directive Stage 3 and 4 assessments considered the potential effects of fully licensed rates of abstraction at Testwood on all intertidal features associated with the Solent and Southampton Water SPA. The conclusions of the Habitats Directive assessment have been used within this Lower Test NEP study for the effect of the Testwood PWS upon intertidal habitats: the assessment concluded that the abstraction had no adverse impact upon the SPA features.

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Table 8.1 Summary of the findings of the Lower Test NEP Investigation upon physical aspects of the River

Topic Summary of findings

The study This NEP investigation has focused on the lower reach of the River Test SSSI: the reach of the river downstream of the M27, and upstream of the river‟s entry into Southampton Water, see Figure 1.1.2. area The time period considered by the investigation is 1996–2011, as this is the period for which reliable and robust flow measurements are available from Testwood Gauging Station.

Physical The study reach (the channel of the Lower Great Test) is a heavily modified watercourse, and has been subject to channel modification and bank reinforcements, and there are water level control structures along much of its environment length. baseline The Test Valley was historically managed as a water meadow system and the ridge and furrow microtopography from such practises is still evident from aerial photographs, however, this type of management is no longer undertaken. There are a large number of places where water is removed from the main channel of the Test, either from unlicensed flow splits, or licensed abstractions (consumptive or non-consumptive). The River Test SSSI Unit 91 is considered to be “unfavourable no change” by Natural England for a variety of reasons, including abstraction, channel structure and the presence of invasive species. The Habitats Directive Stage 3 and 4 assessments considered the potential effects of fully licensed rates of abstraction at Testwood on all intertidal features associated with the Solent and Southampton Water SPA and concluded no adverse impact Historic surveys show the presence of key protected species but recent surveys have not been undertaken for a number of years due to lack of access to the River. Breeding waders have not been recorded in the Lower Test Valley for a number of years.

Hydrology The reach under study is subject to tidal influence and there is a freshwater to saline environmental gradient across the study site. The dominating effect of the tidal regime and operation of water level control structure means and that the hydrological behaviour of the study reach is like that of a lacustrine system than a freely flowing river system. Typical naturalised (un-abstracted) flows in the Lower Test range from 2.5 m3/s (216 Ml/d) in very dry (low abstraction winter recharge) years to up to 7 m3/s (605 Ml/d) in very wet (high winter recharge) years. The historic volume abstraction at Testwood PWS is on average approximately 0.69 m3/s (60 Ml/d), which is about 44% of the daily licence of 1.6 m3/s (136.38 Ml/d). In summer months the average is closer to 0.71 m3/s (61 Ml/d) and in the winter months it is closer to 0.65 m3/s (56 Ml/d). On rare occasions (18 days over 1996–2011) peak abstraction rises above 1.16 m3/s (100 Ml/d) and on 2 days in that period it rose above 1.39 m3/s (120 Ml/d). As the volume of water abstraction is relatively constant at 60 Ml/d, the percentage abstraction taken as a proportion of naturalised flow is highest during low flows and lowest during high flows).

Hydrological A number of cross-sections in the study reach have been measured and input to a hydraulic model. The model has been used to simulate the effect of different abstraction scenarios and water levels control structure settings effects of over the study period of 1996–2011. No data or records are available with regard to actual operation of structures, therefore it is believed that the partially-open model scenario best reflects existing structure management. the The results of the hydraulic model for flows suggest that that effect of the abstraction is greatest immediately downstream of the Testwood abstraction than further downstream due to the contributing flows of the Blackwater abstraction (including the Broadlands Fish Farm Carrier), and the Nursling Fish Farm abstraction. There is no appreciable effect of the effect of other factors at the upstream assessment point, however further downstream, differences and other arise at flows between Q45–100 due backwater effects causing water to spill into the Middle Test. factors The results of the hydraulic model suggest a progressive downstream reduction in the cross-sectional velocities of the Great Test. Overall, the effect of the Testwood abstraction upon velocity is greatest at AP1, and becomes increasingly small downstream under the different abstraction scenarios. The range in velocities due to different abstraction scenarios is significantly smaller than the velocity reduction downstream due to the effect of different structure management scenarios. The tidal regime also has an effect upon water velocities due to backwater effects. In conclusion, it is considered that the effect of the Testwood abstraction upon flow velocities is greatest upstream at AP1, immediately downstream of the Testwood offtake, however downstream other factors have a more significant effect through the backwater effects of water management structures and the tidal regime. The results of the hydraulic model suggest that there is a progressive decline in water level from AP1 to AP4, and that reduction in water level due to different abstraction scenarios is significantly smaller than the effect from structure setting and the tidal regime. The difference in water level between abstraction and structure scenarios are smallest at high flows and greatest at low flows. Given the tidal effect upon water levels, the results with structures closed illustrate the effects of the abstraction alone. The effect of the historic abstraction is greatest at AP1; the effect is reduced downstream at AP4. The effect of the tide upon water level, or rather its indirect effect of tide-locking, is felt for a considerable distance upstream; all the way to AP1. The reason why water levels at AP1 are less affected is most likely due to the broad crested weir which, as it has a high crest elevation, maintains a high water level at AP1 which effectively dampens the tidal signal from propagating further upstream, especially during low flow conditions. In conclusion, it is considered that the effect of historic abstraction at Testwood has a negligible effect on water levels until low flows where the effect is greater, but still relatively small given the background context of the natural tidal cycle and management of structures. Should the abstraction be operating at the full licensed volume at time of very low flow however, the effect of the abstraction becomes more significant.

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Table 8.2 Summary of the findings of the Lower Test NEP Investigation upon ecological aspects of the River

Stated assessment Receptor The Environmental outcomes that are expected are: NEP Investigation outcome requirements

Environmental Objective 1. Current/Historical levels of abstraction – On the basis of the wide range of assessments described above, it is possible to conclude with a high degree of confidence that the risks posed by current levels of 1. A flow regime in the lower River Test that maintains or improves passage for migrating salmon abstraction to this Environmental Objective are low. Full licensed abstraction – There is a high degree of confidence that the Effect of abstraction regimes on risks to Environmental Objective 1 associated with abstracting the full licence are low. 2. The effective screening of all abstraction intakes to prevent fish being drawn in and trapped at hydrological and temperature Salmon any stage of their life cycle – and impact upon migration of Environmental Objective 3: Current/Historical and Full licensed abstraction the overall conclusion of this study is that there 3. The maintenance of a water temperature profile in the lower River Test which is not raised as salmon populations. is a high degree of confidence that the risk posed by the Testwood abstraction (current levels and full licensed quantities) to a result of increased abstraction and is as resilient as possible to climate change the temperature regime of the Lower Test, and thus the aims of Environmental Objective 3, is low. The MRF flow condition is considered to pose a low risk to the thermal regime of the Lower Test particularly given that such low flows are highly unlikely to be experienced in warm summer conditions more than once in 100 years.

Although the flow requirements  A flow regime in the lower River Test that maintains or improves passage for migrating sea for sea trout differ slightly that trout detailed for salmon can used for The assessment of the relationship between the flow regime and water temperatures shows that the risks posed by the water  The effective screening of all abstraction intakes to prevent fish being drawn in and trapped at both species. However the Sea Trout temperature regime to the sea trout population will not be materially increased by abstraction at Testwood. A similar any stage of their life cycle impact on sea trout of any conclusion can be drawn with regard to the risks posed to sea trout migration. changes in water temperature  The maintenance of a water temperature profile in the lower River Test which is not raised as a identified in the salmon work result of increased abstraction and is as resilient as possible to climate change should be assessed separately  The maintenance of a flow regime in the lower River Test which does not cause brown trout habitat to be reduced or degraded • the effective screening of all abstraction intakes to prevent fish being drawn in and trapped at any stage of their life cycle As shown in Table 1.2.1, the Environment Agency has stated that "the River Test below the Testwood public water supply Brown trout  n/a The maintenance of a water temperature profile in the lower River Test which is not raised as a intake is not characteristic Brown Trout habitat therefore no specific monitoring is required for this species.” result of increased abstraction and is as resilient as possible to climate change  The maintenance of good water quality with high levels of dissolved oxygen  The maintenance of a flow regime in the lower River Test which does not cause grayling habitat to be reduced or degraded  The effective screening of all abstraction intakes to prevent fish being drawn in and trapped at Grayling any stage of their life cycle n/a The conclusions of the salmon assessment work are relevant also to grayling.  The maintenance of a water temperature profile in the lower River Test which is not raised as a result of increased abstraction and is as resilient as possible to climate change  The maintenance of good water quality with high levels of dissolved oxygen  The maintenance of a flow regime in the lower River Test which does not cause eel habitat to be reduced or degraded Eel n/a As shown in Table 1.2.1, the Environment Agency has stated that no specific assessment is required for this species  The effective screening of all abstraction intakes to prevent eels being drawn in and trapped at any stage of their life cycle  The maintenance of a flow regime in the lower River Test which does not cause bullhead habitat to be reduced or degraded  The effective screening of all abstraction intakes to prevent fish being drawn in and trapped at any stage of their life cycle The stated requirements for bullhead are that water depths do not fall below 5 cm: the analysis undertaken in Section 5 and 6  Bullhead The maintenance of a water temperature profile in the lower River Test which is not raised as a Impact on water levels shows that the abstraction does not cause water levels to fall below a depth of 5 cm and therefore the effect on bullhead is result of increased abstraction and is as resilient as possible to climate change insignificant.  he maintenance of good water quality with high levels of dissolved oxygen  The maintenance of a flow regime which prevents water levels in appropriate Bullhead habitats from being reduced to below 5 cm.  a flow regime in the lower River Test that maintains or improves passage for migrating lampreys  the effective screening of all abstraction intakes to prevent lamprey being drawn in and trapped at any stage of their life cycle  the maintenance of a flow regime in the lower River Test which does not cause lamprey Lamprey habitat to be reduced or degraded n/a The conclusions of the salmon assessment work are relevant also to lamprey.  The maintenance of water levels which do not prevent or impede access for Lamprey migrating up or down stream.  The maintenance of a flow regime which does not reduce water quality  The maintenance of good water quality

The effects of the different abstraction scenarios upon water levels as determined by the hydraulic model shows that the Water vole  The maintenance and if necessary restoration of water vole populations within the lower Test Impact on water levels effect of the Testwood abstraction is relatively small and limited in extent spatially to the reach downstream of the abstraction

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Stated assessment Receptor The Environmental outcomes that are expected are: NEP Investigation outcome requirements to a favourable conservation status. and upstream of the Blackwater confluence. Other influences have an effect on conditions for water voles such as the operation of water level control structures. It should be considered that there is minimal suitable habitat present in the study  Favourable conservation status will be defined when: reach for this species due to the heavily modified nature of the river. o population dynamics data indicate that it is maintaining itself on a long-term basis as a Current/Historical levels of abstraction – There is a high degree of confidence that the risks posed by current levels of viable component of its natural habitats; abstraction to water voles are low. o the natural range of water vole in the lower Test is neither being reduced nor is likely to be Full licensed abstraction – There is a high degree of confidence that the risks to water voles associated with abstracting the reduced for the foreseeable future; and full licence are low. o there is, and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis

 The maintenance and restoration of wetland habitats upon which otters are dependent  The maintenance and if necessary restoration of otter populations within the lower Test to a favourable conservation status. The modelled results of the different abstraction scenarios upon flows and water levels shows that the effect of the Testwood abstraction is relatively small and limited in extent. The assessment of fisheries study indicate the Testwood abstraction  Favourable conservation status will be defined when:- would not affect the habitat or prey favoured by otters. Impact on "identified features of Otter o population dynamics data indicate that it is maintaining itself on a long-term basis as a Current/Historical levels of abstraction – There is a high degree of confidence that the risks posed by current levels of importance to otters" viable component of its natural habitats; abstraction to otters are low. o the natural range of otter in the lower Test is neither being reduced nor is likely to be Full licensed abstraction – There is a high degree of confidence that the risks to otters associated with abstracting the full reduced for the foreseeable future; and licence are low. o there is, and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis.

The wet grassland results (see below) are also pertinent to assessing the effect upon breeding waders as the potential  With apparent and predicted rises in sea level, it is important that the habitat suitable for impact pathway of the Testwood abstraction is indirect via a reduction of floodplain water tables. The output of the wetland breeding waders is able to migrate landwards. This should not be compromised by abstraction model in simulating wetland water tables show that the effect of different abstraction scenarios was negligible due to the of water and subsequent changes to ground water levels and the seasonal flooding and drying dominance of rainfall and evaporation processes. Further, only a limited part of the Lower Test Valley SSSI is connected to Breeding of the flood plain necessary to create the specific micro-habitats necessary to support breeding Impact on habitat water tables the River Test downstream of the Testwood abstraction and the historic areas of breeding wader habitat lie outside this area. Waders wader populations. Current/Historical levels of abstraction – There is a high degree of confidence that the risks posed by current levels of  Abstraction from the lower River Test should not reduce or compromise the ability to manage abstraction to breeding waders are low. water levels in the floodplain to encourage the restoration of viable populations of breeding – wading birds in the face of sea level rise. Full licensed abstraction There is a high degree of confidence that the risks to breeding waders associated with abstracting the full licence are low.

The wet grassland results (see below) are also pertinent to assessing the effect upon passerines as the potential impact pathway of the Testwood abstraction is indirect via a reduction of floodplain water tables. The output of the wetland model in simulating wetland water tables show that the effect of different abstraction scenarios was negligible due to the dominance of  Sufficient flow is required in the main river to maintain the range of reed swamp and fen rainfall and evaporation processes. Further, the dominant control upon flows into the Middle Test is the setting of the water vegetation types needed by this group of nesting birds Passerines Impact on habitat water tables levels structure.  Sufficient flow is provided to maintain a supply of water to the Middle River and Current/Historical levels of abstraction – There is a high degree of confidence that the risks posed by current levels of restore/maintain transition of reed bed, swamp and saline influence habitats. abstraction to passerines are low. Full licensed abstraction – There is a high degree of confidence that the risks to passerines associated with abstracting the full licence are low.

Historic macroinvertebrates records indicate very high water quality in the study reach, Examination of historic and recent aquatic macroinvertebrate data for the NEP reveal very high quality assemblage is present immediately downstream of the Testwood abstraction. There is an insufficient long dataset with which to generate robust ecological minimum flow relationship. However, no evidence of flow stress has been identified from examining the species present, and from the The maintenance of a flow regime in the lower River Test which: calculated LIFE scores.  Maintains a habitat as characterised by the long-term health of the invertebrate population, Current/Historical levels of abstraction – comparative analysis of the macroinvertebrate communities has not identified flow downstream of the abstraction intake. stress arising from historic Testwood abstraction and therefore there is a high degree of confidence that the risks posed by Macro- current levels of abstraction to floodplain invertebrates are negligible. invertebrates  Maintains habitats required to support the diverse and rare fauna present in the lower River Impact on flow – main river Test Assessing the effects of the fully licensed abstraction is more difficult as a robust relationship between flow statistics and channel  To deliver the first outcome, an ecological minimum flow must be set. This will use invertebrate macroinvertebrate data cannot be made. The outputs of the hydraulic model were used instead to examine the change in community data, specifically LIFE scores and correlating them to gauged daily flows. The velocity although there is uncertainty over the significance of the velocity reduction and whether or not it would affect the „tipping point‟ will be when the communities no longer achieve what is expected of such a macroinvertebrate community. The affected reach extends to only 145 m reach downstream of the intake under low lows, and diverse, abundant ecosystem. the expected frequency of the effects is considered to be small. Given these factors, The conclusion therefore is that the risk of the fully licensed abstraction to the macroinvertebrate community is low. Leading on from this conclusion is a recommendation to continue the existing macroinvertebrate monitoring programme to build a larger dataset which can be used to derive relationships with flow metrics.

Floodplain  Freshwater flows must be sufficient to maintain transitions from fresh to brackish and fully Impact on the floodplain The potential impact pathway of the Testwood abstraction is indirect via a reduction of floodplain water tables. Examination of Invertebrates saline habitats both within the flood plain and along the main freshwater fed water courses, in wetlands including flooding the flow impact pathway to assess the effect of the abstraction upon wetland habitats in the floodplain show that due to the

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Stated assessment Receptor The Environmental outcomes that are expected are: NEP Investigation outcome requirements particular the Middle River. period and flow regime. Flows influencing factors of water level control structures and the tidal regime, the area potentially affected by the Testwood to the Middle River are included abstraction is limited to a small number of fields adjacent to the Middle Test channel. The output of the wetland model in  The period and extent of flood plain inundation needs to be maintained and allowed to migrate in this assessment simulating wetland water tables show that the effect of different abstraction scenarios was to change in-field water tables by inland in the face of sea level rise. approx. 0.01 m in late summer. Further, the dominant control upon flows into the Middle Test is the setting of the water levels  Flow velocities needs to be maintained in terms of both the frequency and duration of peak structure. flows and summer low flows. Current/Historical levels of abstraction – There is a high degree of confidence that the risks posed by current levels of abstraction to floodplain invertebrates are low. Full licensed abstraction – There is a high degree of confidence that the risks to floodplain invertebrates associated with abstracting the full licence are low.

It is concluded that the Testwood PWS abstraction has a negligible effect upon White Clawed Crayfish as the effect of the abstraction upon water levels is considered to be relatively small, and such that would not cause water levels to become excessively low. It should be considered that there is minimal suitable habitat present in the study reach for this species. The maintenance of a flow regime in the lower River Test which: Further, turbidity and sedimentation of the reach downstream of the abstraction occurs through the confluence of the White Clawed Impact on white clawed crayfish  Does not cause White-Clawed Crayfish habitat to be reduced or degraded. Blackwater and from structure management, further reducing the quality of any available habitat. Crayfish habitat Current/Historical levels of abstraction – There is a high degree of confidence that the historic abstraction poses a negligible  Provides sufficient flow at all times to maintain water quality and levels. risk to White Clawed Crayfish. Full licensed abstraction – There is a high degree of confidence that the risks fully licensed abstraction poses a negligible risk to White Clawed Crayfish.

Historic aquatic macrophyte records do not reflect a chalk river habitat due to the heavily modified nature of the water course. The aquatic macrophyte species present in the lower river are representative species of lentic systems, rather than classic The maintenance of a flow regime in the lower River Test which: chalk stream vegetation reflecting the heavily modified nature of the river, and its water level management. No evidence of Freshwater  Maintains a habitat as characterised by the long-term health of the macrophyte community, flow stress has been identified. Effect on macrophyte habitat Macrophytes downstream of the abstraction intake. Current/Historical levels of abstraction – There is a high degree of confidence that historic abstraction poses a negligible risk  Habitats required to support the rare and diverse flora present in the lower Test River. to aquatic macrophytes. Full licensed abstraction – There is a high degree of confidence that fully licensed abstraction poses a low risk to aquatic macrophytes.

 The current range of water levels experienced in the main river (high and low flows) is not increased in range by abstraction.  The availability of water flowing from the main river into the network of ditches in the floodplain is not decreased by abstraction (an increase in volumes may be acceptable, as long as the Examination of the flow impact pathway to assess the effect of the abstraction upon wetland habitats in the floodplain show Lowland Wet new flow is maintained thereafter and this does not damage existing fen meadow that due to the influencing factors of water level control structures and the tidal regime, the area potentially affected by the grassland/Fe communities). Testwood abstraction is limited to a small number of fields adjacent to the Middle Test channel. The output of the wetland n, Carr,  The groundwater levels and soil moisture in the floodplain are not lowered or otherwise model in simulating wetland water tables show that the effect of different abstraction scenarios was to change in-field water Impact on water levels and Marsh, affected; as a result of abstraction (ideally the ground water levels and soil moisture need be tables by approximately only 0.01 m in late summer. water tables Swamp, increased to benefit the range of floodplain ecology – as advocated by the initial WLMP). Current/Historical levels of abstraction – There is a high degree of confidence that the risks posed by current levels of Reedbeds abstraction to wetland habitats are low.  Water levels within the network of floodplain ditches are maintained, and not reduced or Habitats otherwise modified as a result of abstraction. Full licensed abstraction – There is a high degree of confidence that the risks to floodplain wetland habitats with abstracting the full licence are low.  The diversity and extent of wetland habitats, as characterized by in-stream and floodplain wetland vegetation communities, is increased, if not maintained, as a result of abstraction. There will be no loss of wetland vegetation community types, or radical changes in the extent of existing wetland habitats.

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Given the modified nature of the key reaches of interest to the NEP investigation, there are a number of key areas where measures could be taken to enhance the geomorphological and habitat diversity of the river and its riparian edge. These measures relate to privately owned structures and so are outside of the remit of the NEP Investigation. Nevertheless they are included here to provide suggestions on potential habitat enhancement work that could be undertaken as part of the Water Framework Directive. Any modifications to the structures at Testwood Pool that would decrease the height and ultimately the extent of the backwater effect upstream would provide significant habitat enhancement benefits to the river. Currently the reach extending up to the confluence of the Blackwater and upstream suffers from the effects of the backwater with many of the features in the in-stream environment currently being drowned out by this effect. Lowering the magnitude of the backwater effect will help uncover bed features through the re- establishment of free flowing conditions. Modifications to the structures at Testwood Pool could also help to improve sediment continuity downstream. While the current sediment management strategy for the Lower Test is unknown, the Water Framework Directive best practice guidance suggests that sediment should only be removed if there is a proven flood risk. Otherwise it is recommended that sediment is maintained in the system for the biodiversity gains associated with it. The modifications would have to be significant to change the current state as a result of the large sediment sink that exists upstream of Testwood Mill. Any modifications to the structure would need to be agreed with the landowners of the site and could help to achieve the mitigation measure for this water body namely „Operational and structural changes to locks, sluices, weirs, beach control, etc‟. Any alteration to the structure is likely to change the chemical composition of the river upstream as the Testwood Mill is currently the tidal limit in this section of channel. However, any modification to the river channel and banks as outlined above should be undertaken with a view to the effects that will be caused by the tidal regime. Currently, the structures at Testwood Mill provide a barrier to the upstream surge of tidal water up the Great Test. Lowering or removing the structures has the potential to considerably change the current hydrology, aquatic ecology and water chemistry of the Great Test through the influx of tidal water.

8.4. Monitoring

While the conclusion of the Lower Test NEP is that the risks to fish and ecological receptors is low, it is considered prudent to continue existing data collection and monitoring programmes in order to expand and/or enhance current datasets. This means that should future reviews of the Testwood abstraction be necessary, they will have the benefit of additional data to that collated and analysed this NEP Investigation.

The key areas for new or continued data collection have been identified as follows:

 Flow and water level;

 Conductivity / salinity monitoring;

 Tidal and freshwater water temperature;

 Salmon counts/behaviour in the lower river and/or estuary;

 Fish counts (with ongoing maintenance and improvement of the fish counters); and

 Aquatic macroinvertebrates.

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The Testwood abstraction is sited at the natural hydraulic limit of the tide. This is the ideal location for a “run of river” abstraction in that it minimises the risk to freshwater habitats and species without compromising the operational integrity of the abstraction. With regard to potential impacts on the transitional habitat and species downstream, the flow regime is dominated by the interaction between river flows, the tidal regime and the impounding structures at Testwood Mill; the investigation has demonstrated that the influence of abstraction on this flow regime is limited, even under low flow conditions with full licensed abstraction. Following a comprehensive review of the available data and a range of potential flow regimes it is concluded that the risks presented by the Testwood abstraction licence to the habitat and species of interest in the Lower Test, including migratory fish, are low.

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Mainstone, C.P. 2011 An evidence base for setting flow targets to protect river habitat. Natural England Research Reports, Number 035. Natural England, Sheffield. Abishek, S., Srinivasa Ramanujam, K. and Katte, S.S., 1995, "View Factors between Disk/Rectangle and Rectangle in Parallel and Perpendicular Planes," J. Thermophysics, vol. 21, no. 1, pp. 236–239. Acreman, M.C. and Dunbar, M. April 2010 Ecologically acceptable flows in chalk rivers. Report to the Chalk Rivers HAP Steering Group. CEH, Wallingford. Final Report July 2010. Armstrong A.C., and Rose S. 1998 Managing Water for Wetland Ecosystems: A Case Study in Joyce, C.B., and Wade, P.M., (eds.) European Wet Grasslands: Biodiversity, Management and Restoration. John Wiley and Sons Ltd. Armstrong, A.C. 1993 Modelling the response of in-field water tables to ditch levels imposed for ecological aims: a theoretical analysis. Agriculture, Ecosystems and Environment 43: 345–351. Atkins 2005 River Kennet SSSI Low Flows Investigation (8LTC/E8). Final Report. Report to Thames Water Barsoum, N., Anderson, R., Broadmeadow, S., Bishop, H. & Nisbet, T. (2005). Development of ecohydrological guidelines for wet woodland – Phase 1. English Nature research Report 619. Benstead, P., Jose, P., Joyce, C., Wade, P. 1999 European Wet Grassland: Guidelines for Management and Rehabilitation: Guidelines for Management and Restoration RSPB, Sandy Bettey, J. (1999) The Development Of Water Meadows In The Southern Counties. In Cook, H. And Williamson, Water Management in the English Landscape. University Press Cranston, E. & Darby, E. (2004) Ranunculus in Chalk rivers. R&D Tech. Report W1–042/TR, Environment Agency, Bristol, UK. Dawson F H, Castellano E and Ladle M, (1978) Concept of Species Succession in Relation to River Vegetation and Management. Verh. Internat. Verein. Limnol. 20, 1429–1434, Stuttgart, October 1978. Dawson, F.H. (1976) The annual production of the aquatic macrophyte Ranunculus penicillatus var. Calcareus (R.W. Butcher) C.D.K. Cook. Aquatic Botany 2: 51–73. Dawson, F.H., Clinton, E.M.F. and Ladle, M. 1991. Invertebrates on cut weed removed during weed-cutting operations along an English river, the River Frome, Dorset. Aquaculture Research Volume 22, Issue 1, pages 113–132. Dunbar, M.J., Keller, V. and Young, A.R. 2006. DRIEDUP (Distinguishing the Relative Importance of Environmental Data Underpinning flow Pressure Assessment). Report to the Environment Agency EMCAR programme. Environment Agency (undated) Fact File 11 The River Test. Environment Agency Environment Agency 2009b River Basin Management Plan, South East River Basin District. December 2009 Environment Agency, 2006a. Test and Itchen Catchment Flood Management Plan Final Strategy. Environment Agency. Environment Agency, 2006b. The River Test Water Level Management Plan. Environment Agency Environment Agency, 2009a. Lower Test Project Phase 1 Flow Diversion Scoping Report. Environment Agency Environment Agency, 2009c Test & Itchen CAMS Conceptualisation Report, February 2009 Environment Agency, 2010a. Lower Test Project Phase 1, Testwood Public Water Supply Abstraction Impact Investigation – Statement of Issues & Assessment Version 2.0. 25 March 2010. Environment Agency Environment Agency, 2010b. Managing Water abstraction June 2010. Environment Agency Available from: http://publications.environment-agency.gov.uk/PDF/GEHO0310BSBH-E-E.pdf

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