CANDOVER ABSTRACTION LICENCE (SO/042/0031/026) RENEWAL 2016 SOLENT and SOUTH DOWNS AREA TECHNICAL ASSESSMENT FINAL REPORT 11Th A

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

CANDOVER ABSTRACTION LICENCE (SO/042/0031/026) RENEWAL 2016

SOLENT AND SOUTH DOWNS AREA TECHNICAL ASSESSMENT

FINAL REPORT

11th August 2016

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Summary and background

We own the Candover abstraction licence (SO/042/0031/026), and the associated augmentation scheme infrastructure in the upper Itchen groundwater catchment. The extant licence is time-limited and is due to expire on 31st December 2016.

Before the Candover licence can be renewed, we need to demonstrate that it is environmentally sustainable, in line with Agency policy on licence renewals. The other tests are: continued justification of need; and demonstration of efficient use of water.

This is a broad test, but includes the need for a detailed assessment of the impact the Scheme could have on all designated sites as well as considering any potential impacts on non-designated environmental features. This work also needs to consider compliance with objectives specified in the South East River Basin Management Plan. Only if it can be demonstrated that the Scheme has no unacceptable environmental impacts and it meets the remaining two other tests for renewal, can the licence be renewed.

Our assessment has shown that the abstraction regime in the Candover sub-catchment of the upper Itchen impacts upon river flows, is causing almost constant failure of ecologically-based flow targets, and has potential uncertain risks to floodplain wetlands and chalkstream headwaters. The key licences are not operated to their full licence limits, so the potential risks of increased abstraction are real. We present our technical assessment and evidence in a series of four reports (Parts 1 and 2, an Appropriate Assessment, and this Final Report) all of which should be referred to for data analysis, discussion and conclusions.

We have completed an Appropriate Assessment of the licence and concluded: taking account of the proposed new licence conditions identified through the assessment process, and in view of the SAC Conservation Objectives, a conclusion of no adverse effect on the integrity of the River Itchen SAC arising as a result of the Candover licence (when considered alone, or in-combination with other abstraction licences) can be reached, in the short-term, defined as 31st December 2022. Thereafter, we cannot show that the licence would not have an adverse effect on the integrity of the River Itchen SAC.

Furthermore, our assessment of wider ecological impacts and risks concluded:- taking account of the new licence conditions, and considering the unfavourable condition of the site, we conclude that, in the short-term defined as 31st December 2022, the Candover licence is not likely to damage the flora, fauna or geological or physiological features which are of special interest in the River Itchen SSSI, or priority habitats and species. Thereafter, we cannot show that the licence would not have an adverse effect on the integrity of the River Itchen SSSI, or priority habitats and species.

We will renew the licence, on a temporary, short-term basis only, and under very different terms to the extant licence.

Re-balancing the abstraction regime to restore a natural flow regime, with natural variability, is required to sustain natural processes that shape the form and function of the Candover Stream and support the chalkstream biotope. A step-change in effort to restore a natural flow regime is imperative if the ecological interests are ever to achieve favourable condition. A system that requires intervention like augmentation to achieve ecologically-based flow targets cannot by definition be a long-term self-sustaining one.

However, restoring a more natural flow regime will take time. We will investigate the abstraction licences that affect the Candover- sub catchment through the water company National Environment Programme (NEP) process. Scoping and investigations will be carried out in NEP6 (2020-2025) with option implementation starting in NEP7 (2025-30). In the meantime, the impacts and risks to the Candover from those licences will continue unabated.

In the meantime, to counter these risks, we will retain the Candover licence, with the capacity to augment river flows, in the event it is needed for ecological support. In that respect it is a ‘safety-net’, or insurance policy, should the Environment Agency and Natural England agree it is needed at any particular time, whilst the effects of, and risks from, other extant licences remain in place. This is a short-term measure - we will time-limit the licence to 2022 to review the ‘need’. It is possible the need will remain until the NEP investigation is complete and actions implemented i.e. beyond 2025. We do not foresee augmentation being part of the long-term solution.

This report presents the changes we will make to the Candover abstraction licence when we renew it this year. We will :-

 significantly reduce the licence limits;  add new conditions to the licence;  time-limit the licence. 2

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Our Part 1 and Part 2 assessments of the existing Candover licences

The conclusions of our Part 1 report assessment of the hydrological effects of the existing Candover licence are summarised in a series of Tables 8a to 8d, taken from our Part 1 report, and set out in Appendix A to this Final Report.

The conclusions of our Part 2 report assessment of the ecological effects of the existing Candover licence are summarised in a series of Tables 7.1 to 7.3, taken from our Part 2 report, and set out in Appendix B to this Final Report. The ecological risks from the existing Candover licence are also summarised below.

River Itchen SAC

 The existing Candover licence can be shown to be having a likely significant effect on the River Itchen SAC, alone (moderate confidence). An Appropriate Assessment is required before the licence could be considered to be sustainable in the short or long term. Until then the licence cannot be renewed in its existing form.

 In-combination with extant groundwater abstraction licences in the Candover aquifer, the existing Candover licence can be shown be having a likely significant effect the River Itchen SAC (moderate confidence). An Appropriate Assessment is required before the licence could be considered to be sustainable in the short or long term. Until then the licence cannot be renewed in its existing form.

 Other extant abstraction licences that effect the groundwater and surface water of the Candover valley require assessment against the tests of the Habitats Regulations, 2010 because our work shows they are causing river flows to frequently fail a suite of ecologically-based river flow targets, including revised CSMG (moderate confidence).

River Itchen SSSI

 The existing Candover licence alone presents uncertain negative risks to the River Itchen SSSI (wetland habitats and associated bird populations), potentially sufficient to prevent restoration to favourable condition (uncertain confidence). Further investigation is required before the licence could be considered to be sustainable in the short or long term, until then the licence cannot be renewed in its existing form.

 In-combination with extant groundwater abstraction licences in the Candover aquifer, the existing Candover licence presents uncertain negative risks to the River Itchen SSSI, potentially sufficient to prevent restoration to favourable condition (uncertain confidence). Further investigation is required before the licence could be considered to be sustainable in the short or long term, until then the licence cannot be renewed in its existing form.

River Itchen priority habitats and species

 The existing Candover licence alone presents uncertain negative risks to a range of priority wetland habitats and associated species in the Candover Stream floodplain (low confidence). Further

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

investigation is required before the licence could be considered to be sustainable in the short or long term, until then the licence cannot be renewed in its existing form.

 In-combination with extant groundwater abstraction licences in the Candover aquifer, the existing Candover licence presents uncertain negative risks to a range of priority wetland habitats and associated species in the Candover Stream floodplain (low confidence). Further investigation is required before the licence could be considered to be sustainable in the short or long term, until then the licence cannot be renewed in its existing form.

Wider biodiversity

 The existing Candover licence alone presents uncertain negative risks to the chalkstream headwater habitats on the River Alre, River Dever, River Wey & Candover Stream (low confidence). Further investigation is required before the licence could be considered to be sustainable in the short or long term, until then the licence cannot be renewed in its existing form.

 In-combination with extant groundwater abstraction licences in the Candover aquifer, the existing Candover licence presents uncertain negative risks to the chalkstream headwater habitats on the River Alre, River Dever, River Wey and Candover Stream (low confidence). Further investigation is required before the licence could be considered to be sustainable in the short or long term, until then the licence cannot be renewed in its existing form.

We conclude that the existing Candover abstraction licence cannot be renewed under its current terms because of short- and long-term ecological impacts and risks of impacts. To avoid these ecological risks altogether, or mitigate them to an acceptable level, we have identified a suite of new actions as follows:-

 significantly reduce the licence limits;  add new conditions to the licence;  time-limit the licence.

This Final Report describes and explains the reasoning for these licence changes, and together with our Part 1 and 2 reports, forms the basis of our decisions for effects to the River Itchen SSSI and SAC – this Final Report underpins our Appendix 3 and 11 forms, which are standard templates by which we formally consult Natural England. This Final Report also summarises and takes account of the conclusions of our Appropriate Assessment.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Description and explanation of the changes to the Candover licence:-

Reduce licence limits

For the purpose of sustaining natural function and ecological support, albeit to be used very rarely (or even never at all), the magnitude and duration of abstraction (and discharge into the Candover Stream) needs to be:-

 commensurate with the ecological needs;  sufficiently small to avoid the ecological risks identified with the extant licence; and  comfortably sit within the bounds of natural flow conditions experienced by the ecology.

To that effect, we will limit the licence to 5Mld and 750Ml/yr.

Hourly Daily Annual Period Existing licence 350 l/s 27,000 m3 per day 3,750,000 Year round (20,000 m3 per day m3/yr between 1st May and 365 days per 31st August) (3,750 Ml/yr) year New licence limits 209 m3 per 5,000 m3 per day 750,000 m3/yr Year round hour (5 Mld) (750 Ml/yr) 365 days per 60 litres per year second

Table 1: showing new licence limits for the new Candover abstraction licence compared to the existing licence

We identified the new daily figure as appropriate to only augment the Candover Stream at a level that would avoid risks identified in our Part 2 assessment and Appropriate Assessment to sensitive ecology, and to provide a flow that is sufficient to not only support extreme low flows but also off-set, mitigate for abstraction impacts. The annual amount is scaled to reflect the reduction in daily rate and to allow use over a constrained period.

Further new conditions to the licence

Licence Proposed new condition Reason / Purpose Condition Successive use Following use, the Candover scheme To provide protection to wide ranging cannot be used again until flows in the habitats and species and ensure any Candover Stream, measured at Borough impacts from use of the Scheme are Bridge Gauging Station, have recovered to recoverable; and to allow the ecology to at least “normal” for the time of year, with experience natural flows (including

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

reference to the EA Monthly Water natural variability) un-impacted by the Situation report plots, for at least 22 Candover licence, to grow capacity for months in a 24 consecutive month period. self-repair and self-renewal under dynamic conditions, in which a Following that period (which is variable, as minimum of abstraction-related it is due to prevailing weather conditions), disturbance is allowed, or intervention the Scheme cannot be used for a fixed 4 required. This will contribute to year (48 month) period (irrespective of flow restoration of favourable condition and variability and conditions). hence site integrity. Time limit Time limit to December 31st 2022 The standard CAMS Common End Date would be 31st March 2025 but to allow for our 2021 review of bespoke CSMG and improved RoC flow targets to be implemented, the time limit should be set to 31st December 2022. Environmental Add additional monitoring site upstream of Additional point needed to monitor Schedule The Grange Lakes for macroinvertebrates impacts on non-SAC designated reaches and macrophytes. Table 2: Summary of changes to Candover Scheme licence in 2016 to ensure that the licence is environmentally sustainable in the short-term.

What are the hydrological effects of the new licence?

The proposed new licence will operate at an annual maximum of one fifth of the current abstraction licence and with a daily rate less than one fifth of the current maximum daily rate. This significantly changes the potential impacts that the scheme can have on river flows and groundwater levels. The constraint on how frequently the scheme can be used will restrict how often these more mild impacts can impact on the environment.

To simulate the impact of the proposed new licence conditions, further runs of the groundwater model were made simulating a 5 Ml/d abstraction from the site at Bradley during the period from June to October in 1976, 1992 and 2005. In this scenario, the full licence is used regardless of if the flows indicate that there is a need for it.

As an indication of the difference in impacts, the impact on river flow in the Candover Stream at Borough Bridge as a result of both the current licence and proposed new licence is plotted below.

During use of the Candover Scheme, the augmentation discharge is predicted to have the following effects on River Flows: There is a clear reduction in the number of times that the new licence can be used and the maximum impacts are much reduced. Correspondingly, the negative impacts on flow after the scheme has been turned off are generally smaller although the length of time that the impacts persist is actually similar. When this data is expressed as a percentage of natural flow the negative impacts reduce from a maximum of around -5% to around -1.5%. There is also a reduction in possible impacts on river flow further upstream at Abbotstone. The residual negative impacts reduce from around -13% to around -4.5% whilst the increase in flows as a result of the discharge are much reduced. Modelled impacts on river flow in nearby watercourses are no longer discernable.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Figure 1 – impacts of the new Candover licence on river flows in the Candover Stream

In terms of the impact on River flows upstream of Grange Lakes, after the Candover Scheme has been turned off: In the upper reaches of the Candover Stream, the impact of the Candover licence on its own, after it is used, is predicted to reduce flows by as much as - 20%. The In-combination effects with other extant abstraction licences have yet to be assessed in detail as flows are naturally very variable, but in rare events are predicted to be as high as -50 to -100%, with other abstractions thought to have a far more significant effect. High impacts only expected to last for a few weeks. Low level impacts could prevail for 6 months depending on prevailing conditions and actual use of scheme. Slight reduction in autumn and winter peak flows depending on prevailing conditions and actual use of scheme

River flows downstream of Grange Lakes, after the Candover Scheme has been turned off: The impact of the Candover licence on its own, after it is used, is predicted to reduce flows by -4 to -5% around Abbotstone, and -1 to -2% at Borough Bridge. Impacts from Scheme are predicted to never exceed 2%, and are likely to fall below 1% within 12 months. In-combination with other extant abstraction licences, the Candover licence is shown to contribute to a -10% to -45% reduction in river flows at Abbotstone and can be higher during extreme events; and -25% during high flow periods at Borough Bridge. The drawdown from the groundwater augmentation may decrease the winter Q10 flow. 7

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

After the Candover scheme has been turned off, the predicted impact on the ephemeral stream-head of the Candover Stream is a delay of several days in spring head reaching maximum winter position and the spring head may be up to 100m lower than expected.

Do the new licence limits sit within the bounds of natural flows?

Median flows in summer in the Candover Stream at Borough Bridge range from 0.55 cumecs (cubic meters per second) in May, down to 0.35 cumecs in September. Current restrictions on the extant licence means that it cannot be used unless flows on the River Itchen are below 240 Ml/d. Typically that means that flows on the Candover Stream will be below 0.3 cumecs at that time.

If 5 Ml/d of water is introduced to the Candover Stream (which is equivalent to approximately 0.06 cumecs), at the worst case, flows could be raised from 0.3 to 0.36 cumecs, which is around the level of median flow expected in September, and considerably less than typical flows earlier in the spring.

A typical low flow is around 0.2 cumecs and so this would raise flows to only 0.26 cumecs – well below median flows at any time of year.

Low flow periods tend to occur from May to December but are typically between June/July to October. If the scheme was used at full daily rate for 5 months (worst case) the amount of water abstracted would equate to around 750 Ml. This is the basis of our proposal for the annual rate of abstraction.

Figure 2 below shows the range of flows expected at Borough Bridge and plots scenarios for augmented flow based on the low flow year of 1992 for the existing licence (shown in green) and the proposed smaller licence (shown in red). This clearly shows that for the proposed new licence, flows are maintained within the lower 25% of flows expected for the time of year. In other words, flows do not change from a low flow to an extremely high flow for that time of year. The small magnitude of effect on flows from the reduced licence limits compare favourably to the extant licence which is likely to cause flows to rise from those expected to be exceeded 95% of the time to flows only expected to be exceeded 5% of the time (see Part 1 report Tables 8a to 8d; and Appendix A below).

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Figure 2 – Augmentation scenarios compared with typical flows at Borough Bridge

Do the new licence limits meet our flow targets?

CAMS Ledger The Candover Scheme is included in the Test and Itchen CAMS ledger but is not modelled as being in operation in the Recent Actual Scenario which is used for WFD reporting. In the Fully Licensed scenario, the scheme is modelled to increase low flows by 4 – 5 Ml/d.

At this time, the reported WFD status for the Candover Stream is that both Recent Actual and Fully Licensed flows would remain above the Environmental Flow Indicator (EFI) at all times. This means that flows are defined as supporting good ecological status in the River Basin Management Plan.

However, removing the Fobdown abstraction and associated discharge from the CAMS ledger results in a position where Recent Actual flows would be below the EFI by 1.6 Ml/d at Q95 and Fully Licensed flows would be 2.9 Ml/d below the EFI at Q95. In this case, flows would no longer be supporting Good Ecological Status. This is as a result of the change at Fobdown watercress bed no longer concealing abstraction impacts from other sources. The way that the Candover Scheme is currently modelled in the CAMS ledger acts to mitigate those impacts and does not lead to a worsening of the status for the Candover Stream waterbody.

Revised CSMG Compliance

Revocation of the Fobdown watercress licence also changes revised CSMG compliance from one where the revised CSMG targets are broadly met at Borough Bridge to a position where they are failed for most of the time. Analysis of the flow data suggests that in terms of strict compliance with the targets, they are met for 64% of the time with Fobdown watercress beds in operation, but are only met for 12% of the time now that the Fobdown licence is revoked.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Figure 3 - Revised CSMG compliance with Fobdown licence revoked

With the proposed new version of the Candover Scheme licence there is very little impact on the frequency that flows fall below the flow targets i.e. the targets would already be exceeded due to other existing abstractions. The impact of increasing flows above the target is much reduced compared to the current version of the licence in terms of frequency and magnitude. The maximum impact on flows is to increase them by up to 21% rather than the previous maximum with the current version of the Candover Scheme licence of over 100%. It is worth stating that any hydrological impacts from the Candover Scheme would be infrequent and short duration due to the licence conditions, whereas the impacts from other extant abstractions are having a significant impact all of the time. Revised CSMG flow targets are currently met for both the River Alre and River Itchen at Easton and would continue to be met with the revised smaller licence for the Candover Scheme.

River Itchen RoC Target Flow Compliance The target flow regime used in the Review of Consents assessment was designed for use with daily flow records as measured at the gauging stations on the River Itchen and its tributaries. The groundwater model produces output for stream flow at each of the gauging stations but only at a resolution of two stress periods every month. Compliance with the targets requires the summer Q95 to be calculated for the period from April to September. There are only twelve values to calculate that statistic for each year of the groundwater model output. In addition the targets were derived from observed and not modelled data and there will inevitably be discrepancies between these two data sets. For those reasons, compliance checking of the target flow regime using groundwater model output should be treated as indicative only.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

TARGET Naturalised Current reported Reduced licence compliance with Fobdown licence revoked (1986 – 2015) Long term summer 25 Ml/d 28 Ml/d 29.2 Ml/d 24 Ml/d Q95 must exceed Flow should not 19 Ml/d 16 Ml/d 16.4 Ml/d 17 Ml/d fall below Summer Q95 23 Ml/d in more Fell below 23 Ml/d Fell below 23 Ml/d Fell below 23 should not fall than 1 in 6 years 8 times in 41 years 6 times in 30 years Ml/d 16 times in below 41 years Overall compliance FAIL FAIL FAIL Table 3 Compliance with target flow regime based on output from the groundwater model (1970 - 2010)

The output from the groundwater model shows that the modelled naturalised scenario fails the target flow regime because minimum flows are likely to fall below target 2, and target 3 is breached more times than is allowed. This is because modelled natural flows are lower than recent actual flows which include the compensatory discharge from Fobdown watercress beds. Looking at recently recorded flows shows that the target flow regime is also currently failed under recent conditions as the period of analysis includes low flow periods not included when the targets were initially created. With the proposed revisions to the Candover Scheme licence, considered in the context of the Fobdown licence being revoked, the target flow regime is still breached for targets 2 and 3. The largest impact on this however, is the revocation of the Fobdown licence which makes this failure more pronounced. The implication of these failures for all scenarios is that there could be an impact on the invertebrate community of the Candover Stream.

Figure 4 - Compliance with Target 2 (the minimum flow target) for the Candover Stream 11

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

In Figure 4 it is clear that under natural conditions this target is failed in 1973, 1976, 1989, 1992, 1997 and 2005. Use of the augmentation scheme in 1976, 1992 and 2005 reduces the extent of these failures.

Spatial extent of the Candover licence – existing and new.

Map 1 shows the modelled extent of impacts on groundwater levels after proposed use of the Candover Scheme at the new lower abstraction rate in 1976, 1992 and 2005. For this illustration, 5 Ml/d has been abstracted from the Bradley boreholes from June to October for each period. Unsurprisingly the extent of the cone of depression is very similar for each event.

Considering use of the Candover Scheme alone and impacts on groundwater levels in the Candover valley: Groundwater levels may be reduced by up to 1m in a small area in the upper Candover Valley with reductions of the order of 0.1m only extending to Chilton Candover and no measurable impact at Abbotstone. Impacts greater than 1m will persist in the upper valley during use of the scheme but will rapidly recover after scheme is switched off. Smaller impacts in the upper valley of less than 0.5m may last for a few months.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Map 1: showing the maximum modelled extent of the cone of depression of the new licence. The plot shows the 0.1m drawdown contour for the end of October in 1976 (black), 1992 (green) and 2005 (orange). The small contours are at 1m drawdown just to indicate the site location.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Map 2 is taken from the Part 1 report, and shows a consolidation of measured and modelled data to show the maximum possible extent of impacts on groundwater levels. This area extends to the headwaters of the River Dever (Test catchment) and River Wey (Thames catchment), as well as the River Alre and Candover Stream. Areas where wetlands could be impacted by reduced groundwater levels are shown shaded pink. The Part 2 report explains this assessment in more detail. Wetlands in the lower Candover valley in particular were identified as potentially at risk.

Map 2: presenting the likely maximum extent of the existing Candover Scheme cone of depression.

Comparison of Maps 1 and 2 clearly show the reduction in risk to wetland sites as a result of reducing the abstraction amounts permitted by the Candover Scheme licence. With the proposal to reduce the Candover Scheme licence we consider that the vulnerable wetlands in the lower Candover Valley would no longer be at risk and there would be no risk to the headwaters of the nearby River Dever, River Wey or River Alre.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Spatial extent of other existing abstraction impacts on groundwater in the upper Itchen

The precise spatial extent of the impacts on groundwater for each of the large abstraction licence has been modelled, and the results mapped in Map 3 below.

This modelling is caveated with clauses that further investigation and more refined modelling is required before firm conclusions can be reached about the precise relative effects (scale, magnitude, alone and in- combination) of each abstraction on the River Itchen SAC. However, it is clear there are large areas of spatial overlap, and also discrete areas of impact. These effects have existed for decades. These potential impacts on groundwater levels could also be having an effect on wetlands in the headwaters of the Dever, Wey, Alre and Candover.

Map 3: Presenting the overlapping data superimposed all four contour sets where :-

Red = Totford Black = Lasham Green = Fobdown watercress bed Purple = Alre & Cheriton watercress farms and fish farms licences

(minimum contour level is 0.1 m)

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Summary of hydrological impacts associated with revised new, smaller Candover Scheme licence

Magnitude of impact Duration of impact Frequency of impact

Candover Slight reduction in autumn and winter peak flows Very low level impacts upstream of depending on prevailing conditions and actual could prevail for 6 months Historically scheme only Grange Lakes use of scheme depending on prevailing likely to be used once in conditions and actual use 10 years. Alone impact - as much as - 20% in upper reaches of scheme. Proposed licence only In-combination - not assessed in detail as flows Moderate impacts only allows scheme to be used are naturally very variable. In rare events, acting expected to last for a few infrequently with gaps of with other licences, impacts can be as high as -50 weeks. at least 6 years between to -100% with other abstractions thought to have use. a far more significant effect

Candover Maximum impact: Impacts from Scheme downstream of likely to fall below 1% Grange Lakes -1 to - 2% alone at Borough Bridge within 4 months, and never exceed 2% - 4 to - 5% around Abbotstone

-25% in combination during high flow periods at Borough Bridge

-10% to - 45% at Abbotstone, and can be higher during extreme events

The drawdown from the groundwater augmentation may decrease the winter Q10 flow.

River Alre Maximum impact: Impacts from Scheme not discernable Less than 1% alone

-10% In combination during high flow periods

Upper Itchen Maximum impact: Impacts from Scheme not discernable Less than 1% alone

-6% In combination

Cheriton Stream Not discernible N/A

Table 8a taken from Part 1 report) Summary of Impact on River flows after Candover Scheme has been turned off.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Magnitude of impact Duration of impact Frequency of impact

Candover Pattern of flow/no flow relatively unaffected. Impacts not discernable above Grange Historically scheme only Lakes Impact on stream heads difficult to model as likely likely to be used once in to be within the bounds of the model resolution. 10 years.

Potential of a delay of a few days in spring head Proposed licence only reaching maximum winter position and spring head allows scheme to be used may be up to 100m lower than expected. infrequently with gaps of at least 6 years between River Alre Pattern of flow/no flow unaffected. Impacts not discernable use

Table 8b taken from Part 1 report) Impact on ephemeral stream-heads after scheme has been turned off.

Magnitude of impact Duration of impact Frequency of impact

Candover Stream Groundwater levels may be reduced by Impacts greater than 1m will persist in up to 1m in a small area in the upper the upper valley during use of the Historically scheme only Candover Valley with reductions of the scheme but will rapidly recover after likely to be used once in order of 0.1m only extending to Chilton scheme is switched off. Smaller 10 years. Candover and no measurable impact at impacts in the upper valley of less than Abbotstone. 0.5m may last for a few months. Proposed licence only allows scheme to be used infrequently with gaps of at least 6 years between River Alre Groundwater levels may be reduced by Impacts of up to 0.1m may persist for use up to 0.1m up to 12 months from when use of the scheme stops

Table 8c taken from Part 1 report) Impact on areas of high groundwater level which may be linked to groundwater dependent terrestrial ecosystems

Magnitude of impact Duration of impact Frequency of impact

Upper Candover Stream already likely to be dry upstream of discharge N/A point so no impact likely whilst scheme in use.

Lower Candover +30% alone Up to 5 months Historically scheme only likely to be used once in In the summer months, average flows in the Candover 10 years. Stream are around 34 Ml/d whilst in dry periods they are below 26 Ml/d. The addition of 5 Ml/d of water Proposed licence only from the augmentation scheme would still leave flows allows scheme to be used below the average expected for the time of year. infrequently with gaps of at least 6 years between Upper Itchen + 1 -4% alone Up to 5 months use

+ 5 % in combination with all other abstractions and discharges from watercress beds.

Table 8d taken from Part 1 report) Impact of augmentation discharge on River Flows, during use.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Consideration of consecutive year use of the Scheme

The Part 1 report explained how the current licence constrains potential use of the Candover Scheme which showed that the licence would allow the Scheme to be used several years in a row during a sequence of dry years.

The main hydrological impacts related to use of the Scheme are:

• During use of the scheme, the discharge of colder water into the Candover Stream with increased flows and velocities. • After use of the scheme, the residual negative impacts on river flow. • During and after use of the scheme, lowered groundwater levels and delayed groundwater recovery in the Candover floodplain and in the headwaters of the Candover, Dever, Wey and Alre.

Our assessment in the Part 2 report shows that these hydrological impacts would only be considered acceptable if they happen on an infrequent basis and would certainly not be acceptable as a repeated sequence of use over a short period.

Chalkstream biotope as characterised by the macroinvertebrate and macrophyte communities:

Our analysis of the literature and local ecological data in the Part 2 document, clearly explains the length of time it could take for the macroinvertebrate and macrophyte communities of the chalk stream biotope to recover from any major impact of flows (positive and negative) as typically taking between one and three years. Whilst the impacts of using the Candover Scheme would be relatively small compared to natural variation, the impacts are nonetheless additive. Simply expressed, the delayed recovery of groundwater from use of the Scheme would make natural hydrological conditions worse, not better.

The Part 2 report also discussed in Chapter 7, the need to restore the River Itchen SSSI and SAC to favourable condition, and describes the concept of allowing the habitats of the Candover Stream to thrive rather than be continually impacted and recovering, in order to contribute towards achieving favourable condition. This leads to the suggestion that to protect the chalkstream biotope, as characterised by the macroinvertebrate, macrophyte and fish communities in the Candover Stream, river flows need to have returned to normal conditions for at least twelve consecutive months before the Scheme can be used again; and once conditions have returned to normal, a further condition is required to restrict how frequently the scheme can be used to allow for normal, un-impacted flow conditions to be the norm, rather than the exception, and thereby allow time and conditions for the river as whole to recover favourable condition in light of a gamut of non- abstraction-related stressors.

The White-clawed crayfish population:

The White-clawed crayfish population are particularly sensitive to exposure to the discharge from the scheme and repeated exposure to the discharge needs to be minimised to prevent negative effects from becoming compounded into chronic or long-lasting population-level effects. In that respect we consider the White- clawed crayfish to be more sensitive to the hydrological impacts (high, cold flows; reduced flows) than the wider macroinvertebrate community. This leads to the suggestion that before the scheme can be used again, 18

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016 flows must have recovered to normal for at least 2 years and to protect them from repeated high use of the scheme, even if conditions have returned to normal, a further condition is required to restrict how frequently the scheme can be used.

Conclusion:

We consider the macroinvertebrate, macrophyte and fish communities, as surrogate for the wider chalkstream biotope, are less sensitive to reduced river water temperatures and changes in flow and velocity (i.e. the increase and the decrease in flows and velocities, and reduced river water temperature predicted with use of the Candover licence) than the White-clawed crayfish population. Nonetheless, our analysis in Part 2 concludes there are significant risks to the chalkstream biotope, and we conclude that a period of 12 consecutive months of normal flows is required before the scheme could be used again, to be followed by a hands-off period.

However, as the White-clawed crayfish is more sensitive, we will base our licence condition on the two-year needs of that SAC interest feature, to be followed by a hands-off period.

Recommendation:

To ensure that both the White-clawed crayfish and the chalkstream biotope are protected (from impacts related to high flows and reduced flows as a consequence of running the Candover scheme), it is suggested that flows in the Candover Stream must have recovered to normal for a period of 2 years - to allow for slight deviations in hydrological recovery, flows need to be at normal or above for 22 out of a 24 consecutive month period.

Following the period of normal flows, there should be a second period to allow the ecology to experience natural flows (including natural variability) un-impacted by the Candover licence, to grow capacity for self- repair and self-renewal under dynamic conditions, in which a minimum of external intervention is required or disturbance allowed. This will contribute to restoration of favourable condition and hence site integrity.

The Environment Agency's routinely produced water situation reports define when conditions in rivers are normal, or above or below that status. This could be used as the basis of a condition to prevent use of the Candover Scheme until flows have returned to normal. This is similar to the approach taken for the West Berkshire Groundwater Scheme.

On that basis, the suggested condition for permitting use of the Candover Scheme following a previous use period to allow recovery from any impacts and to prevent regular exposure of Candover Stream habitats and species to the discharge is:

The scheme cannot be used again until flows in the Candover Stream, measured at Borough Bridge Gauging Station, have recovered to at least “normal” for the time of year, with reference to the EA Monthly Water Situation report plots, for at least 22 months in a 24 consecutive month period. Following that recovery, the scheme cannot be used for a further 4 years.

Figure 5 below shows the water situation report plot for flows at Borough Bridge. This highlights that flows remained below normal for a long period from 1989 to 1992 which meant that even with low use in 1989, 19

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016 flows hadn't reached normal for a period of 24 months until July 1995 and the Scheme couldn't have been used again until July 1999. It would also have precluded use in 1976 if the scheme had already been used in 1973. If the scheme had been fully used in 1973, it wouldn't have been available for use again until April 1982. Applying the conditions above would mean that it is likely that the Candover Scheme could only have been used for four periods in the forty-five year period from 1970 to 2015.

Figure 5 Water Situation Report plot for the Candover Scheme

Time-limit the licence The Candover Stream can be described as having a high degree of ecological integrity when the inherent potential for meeting the site conservation objectives is realised, the capacity for self-repair and self-renewal under dynamic conditions is maintained, and a minimum of external management intervention is required.

Our assessment has shown that the abstraction regime in the Candover sub-catchment of the upper Itchen impacts upon river flows, causing almost constant failure of ecologically-based flow targets, and has potential uncertain risks to floodplain wetlands and chalkstream headwaters. The key licences are not operated to their full licence limits, so the risks of increased abstraction are real.

Re-balancing the abstraction regime to restore a natural flow regime, with natural variability, is required to sustain natural processes that shape the form and function of the Candover Stream and the chalkstream biotope. Only then will the abstraction regime be sustainable. A step-change in effort to restore a natural flow regime is imperative if the ecological interests are ever to achieve favourable condition. A system that requires intervention like augmentation to achieve ecologically-based flow targets cannot by definition be a long-term self-sustaining one.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

2025, and any actions that arise from that will be implemented thereafter. In the meantime, the impacts and risks to the Candover from those licences will continue unabated.

To counter the risks, we will retain the Candover licence, with the capacity to augment river flows in the event it is needed for ecological support. In that respect it is a ‘safety-net’, or insurance policy, should the Environment Agency and Natural England agree it is needed at any particular time, whilst the effects of other extant licences remain in place. This is a short-term measure - we will time-limit the licence to 2022 to review the ‘need’. It is possible the need will remain until the NEP investigation is complete and actions implemented i.e. beyond 2025. We do not foresee augmentation being part of the long-term solution.

The 2022 time-limit also accords with another commitment fixed to that deadline. In 2013 we agreed with Natural England to work together to produce new, bespoke, flow targets for the River Itchen SSSI and SAC by 2021. This would be an amalgam of revised/updated RoC flow targets (incorporating new approach identified by Wilby, 2010) and revised CSMG flow targets). The current assessment does not preclude or negate that commitment. We will limit the Candover licence to 2022, to enable any changes to be made that arise from that work.

The ‘Likely Significant Effect’ test and Appropriate Assessment

Appendix 3 assessment of ‘Likely Significant Effect’

Our assessment of LSE (set out in a standard Appendix 3 form) took account of the new licence limits and conditions, and considered the Conservation Objectives of the site. There are risks of effect from reduced day-time river water temperatures when the scheme is used, and of reduced river flows, from delayed groundwater reviver, following use of the scheme; and effects of high, cold flows when the scheme is in use. The effects of the new Candover licence are not in themselves large in magnitude or spatial scale, or duration, but nonetheless are additive to the effects of existing licences.

 Taking account of the new licence limits and conditions, and considering the Conservation Objectives of the site, we conclude the Candover licence (alone) cannot be shown not to have a likely significant effect on the River Itchen SAC in the short-term, defined as 31st December 2022. Beyond 2022, we cannot be certain that the licence, alone, will not have a LSE.

 Taking account of the new licence limits and conditions set out above, and considering the Conservation Objectives of the site, we conclude the Candover licence, when considered in- combination with other existing abstraction licences, cannot be shown not to have a likely significant effect on the River Itchen SAC, even in the short-term.

As the licence is not directly connected with or necessary to the management of the River Itchen SAC for nature conservation, it is necessary for the Environment Agency, as Competent Authority, to undertake an Appropriate Assessment of the implications of the proposed abstraction licence renewal, in view of the site’s Conservation Objectives, before the renewal can be acceptable.

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Our Appropriate Assessment concludes the following:-

Our Appropriate Assessment is a separate, stand-alone report. It sets out a detailed assessment of adverse effect on site integrity of the River Itchen SAC, in accordance with Regulation 61, The Conservation of Habitats and Species Regulations 2010, from the Candover abstraction licence (SO/042/0031/026) renewal, 2016. The conclusions of our Appropriate Assessment are summarised below:

Clearly, flows in the Candover are impacted by groundwater abstraction in the round. But it is evident that the hydrological effects of the Candover licence alone, barely contribute to the almost constant failure of a number of flow targets. Any effects are also infrequent: most of the time there is zero in-combination effect because the Candover licence cannot be used at all.

Positive and negative effects are likely to only result in short-term ecological change, rather than permanent damage, and are likely to be recoverable, given time, because the licence conditions ensure that the hydrological drivers remain within the bounds of natural variation (in terms of frequency, timing/period, magnitude, rate of change, and duration).

Taking account of the proposed new licence conditions identified through the Appropriate Assessment process, and in view of the SAC Conservation Objectives, a conclusion of no adverse effect on the integrity of the River Itchen SAC arising as a result of the Candover licence (when considered alone, or in- combination with other abstraction licences) can be reached, in the short-term defined as 31st December 2022. Thereafter, we cannot show that the licence would not have an adverse effect on the integrity of the River Itchen SAC.

We are uncertain about the precise nature and scale of potential chronic ecological effects from long-term, constant groundwater abstraction from the other extant abstraction licences on natural processes and associated the physio-chemical attributes of the upper catchment, or how any such potential effects would manifest themselves in ecological condition (species richness, abundance) and function. Without further work we cannot determine the nature, magnitude or duration of these potential chronic hydrological impacts, or their physiochemical and ecological consequences.

We recommend that these abstraction licences be subject to the tests of the Habitats Regulations (61) both alone or in-combination. Those are:-

 Southern Water’s Totford PWS licence (11/42/22.3/55);  South East Water’s PWS Lasham licence (28/39/30/0273) and  Pumped Watercress and Fish Farm licences in the Upper Itchen catchment – not including watercress beds fed by artesian overflowing boreholes. (Itchen Valley Trout Farm 11/42/22.1/136, Pinglestone 11/42/22.2/101, Franklyns Fish Farm 11/42/22.2/148, Drayton 32/068, Bighton Road 32/078)

Our conclusions, predicated on the new licence conditions set out in this report, are nevertheless ‘time- limited’, in that they are sound in the short-term, but not the long term. The licence will be time-limited to enable further assessment in light of planned actions between now and 31st December 2022.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Final Conclusions:-

 The Candover Stream can be described as having a high degree of ecological integrity when the inherent potential for meeting the site Conservation Objectives is realised, the capacity for self-repair and self-renewal under dynamic conditions is maintained, and a minimum of external management intervention is required.

 Our data shows that the hydrological effects of the Candover licence barely contribute to the almost constant failure of a number of ecologically-based flow targets. Most of the time there is zero in- combination effect because, unlike the existing licence, the new Candover licence can only rarely be used. Nevertheless, there are theoretical ecological risks to the River Itchen SAC, and the SSSI, and to wider priority habitats, from the new Candover licence - the new Candover licence is still additive to the impacts of other extant licences. And we have not identified any conditions that remove or mitigate the in-combination effects.

 We have completed an Appropriate Assessment that concludes that the new Candover licence can be shown not to adversely affect the River Itchen SAC, because the new licence conditions remove the risks of likely significant effect, in the short-term only.

 However, in the long-term the extant Candover abstraction licence is not sustainable.

 The new licence is justifiable in the short-term, as there is a perceived ‘need’ for an interim period, whilst other abstraction licences which are considered to have far greater negative effects on the flow regime and ecology of the Candover Stream are subject to investigation. However, even that purpose is not desirable or sustainable in the long-term. We do not foresee augmentation being part of the long-term solution to re-balancing the abstraction regime. Therefore, the licence will be time- limited.

 In the meantime, use of the Scheme will be determined jointly by the Environment Agency and Natural England. There will be a presumption against use.

 Taking account of the proposed new licence conditions identified through the Appropriate Assessment process, and in view of the SAC Conservation Objectives, a conclusion of no adverse effect on the integrity of the River Itchen SAC arising as a result of the Candover licence (when considered alone, or in-combination with other abstraction licences) can be reached, in the short- term defined as 31st December 2022. Thereafter, we cannot show that the licence would not have an adverse effect on the integrity of the River Itchen SAC.

 Taking account of the new licence conditions set out above, and considering the Conservation Objectives of the site, we conclude that, in the short-term defined as 31st December 2022, the Candover licence is not likely to damage any of the flora, fauna or geological or physiological features which are of special interest in the River Itchen SSSI or priority habitats and species. Thereafter, we cannot show that the licence would not have an adverse effect on the integrity of the River Itchen SSSI or priority habitats and species.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

 As a result of the assessment in support of the licence renewal process, we (and Natural England) will initiate a water company National Environment Programme (NEP) project (Southern Water (Totford PWS) and South East Water (Lasham PWS)) to investigate public water supply abstraction impacts on the River Itchen SAC; and potentially the River Itchen SSSI Floodplain wetlands and associated birds in the lower Candover Valley; and potentially BAP chalkstream headwaters (Candover and Alre) and floodplain wetlands and associated species in the lower Candover Valley. Scoping and investigations will be carried out in NEP6 (2020-2025) with option implementation starting asap, in NEP7 (2025-30).

Table 4: Final conclusions for the new Candover licence for the River Itchen SAC, taking account of our Appropriate Assessment

Is there a likely significant effect from the During use of the scheme, After use of the scheme, the During and after use of the new Candover licence on the River Itchen the discharge of colder water residual negative impacts on scheme, lowered groundwater SAC? into the Candover Stream river flow. levels and delayed with increased flows and groundwater recovery in the velocities. chalkstream headwaters. In- In- alone alone alone In-combination combination combination Compounded short-term ecological responses (characterised by the macrophyte and macroinvertebrate no, in the no, in the no, in the short- communities) becoming prolonged change, short- no no no short-term term with possible chronic effects, and reduced term resilience and ability to recover.

Impacts on White-clawed crayfish with compounded short-term effects becoming prolonged change, with reduced resilience no, in the no, in the no, in the short- and ability to recover, (accentuated by the short- no no no short-term term existing isolated nature and inherent term vulnerability of this population), and possible chronic population-level effects. Changes to the spatial extent and ecological condition of the ephemeral winterbourne no, in the short- n/a n/a n/a n/a no reaches of the upper Candover Stream term

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Table 5: Final conclusions for the new Candover licence for the River Itchen SSSI

Is there a likely negative effect from During use of the scheme, the After use of the scheme, the During and after use of the the new Candover licence on the discharge of colder water into residual negative impacts on scheme, lowered groundwater River Itchen SSSI? the Candover Stream with river flow. levels and delayed increased flows and velocities. groundwater recovery in the chalkstream headwaters. In- In- In- alone alone alone combination combination combination Assemblages of breeding birds (waders and passerine species) of no, in the no, in the lowland open waters and their no no no no short-term short-term margins

Floodplain fen (lowland) ; Lowland Mire Grassland And Rush Pasture ; Lowland neutral grassland ; Lowland no, in the no, in the no, in the no, in the wet neutral grassland ; Lowland no no short-term short-term short-term short-term wetland including basin fen, valley fen, floodplain fen, water-fringe fen, spring/flush fen and raised bog lagg Rivers and Streams (characterised by the macrophyte and no, in the no, in the no, in the no, in the no, in the macroinvertebrate communities) no short-term short-term short-term short-term short-term

As for the River Itchen SAC White-clawed crayfish population no, in the no, in the no, in the no no no As for the River Itchen SAC short-term short-term short-term

Table 6: Final conclusions for priority habitats and species

Is there a likely negative effect from During use of the scheme, the After use of the scheme, the During and after use of the the new Candover licence on BAP discharge of colder water into residual negative impacts on scheme, lowered groundwater habitats and species? the Candover Stream with river flow. levels and delayed groundwater increased flows and recovery in the chalkstream velocities. headwaters.

In- In- alone alone alone In-combination combination combination Changes to the spatial extent and ecological condition of the no, in the no, in the no, in the n/a n/a no ephemeral winterbourne reaches of short-term short-term short-term the River Dever and River Wey. Note that the conclusions for all other BAP habitats and Species are the same as presented in Tables 4 and 5 above, for the River Itchen SSSI and SAC.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Operating Manual An Operating Manual is being drafted to explain how to use the Scheme sensitively to secure wider protection for SSSI and BAP species and habitats and reduce flood risk from use of the Scheme. This will include instructions to address some of the issues mentioned in the Site Action Plan which aren’t directly related to securing protection of the SAC like cutting weed in advance of using the Scheme. Although this won’t be a formal part of the abstraction licence, it will be a clear statement of how the operator should use the Scheme.

River Restoration The Environment Agency is committed to completing a programme of river improvement works to 1.4km of Candover Stream (habitat heterogeneity / refugia etc), subject to landowner agreement. Necessary to secure our 2007 RoC conclusions.

The Agency will also investigate potential for habitat restoration / improvements to the Candover winterbourne, as per works successfully carried out by HIWWT in 2012. Explore potential to carryout similar works in the winterbourne headwaters of the Rivers Dever and Wey too

Other Actions The assessment process has identified a number of specific actions on the Agency, as follows:-

1. We are committed to working with Natural England to produce new, bespoke flow targets for the River Itchen SSSI and SAC by 2021 (an amalgam of [improved al la Wilby’s (2010) findings] RoC and revised CSMG flow targets). The current assessment does not preclude or negate that commitment. If we renew the licence, we should time-limit it to 2022, to enable the changes to be made, if necessary, as a result of our planned review.

2. A WFD investigation into impacts of extant groundwater abstraction licences in the Candover aquifer is needed, to complement the NEP investigation assessment.

3. Initiate biological and hydrological monitoring programme in the ephemeral, winterbourne reaches of the Candover, Alre and Cheriton Stream, for macrophytes and macroinvertebrates, to form a baseline for future assessment, and characterise their ecology and help establish the relationships between hydrology and ecology.

4. Instigate a research project to collate data that may help us understand the nature of the Candover winterbourne (i.e. historical photos, interview key people/history societies, Council archives etc).

5. Review macroinvertebrate monitoring programme in upper Itchen.

Amendments to Environmental Schedule An environmental schedule has been defined to allow for continued monitoring of macrophytes and invertebrates at Borough Bridge and Abbotstone on the Candover Stream. This data has to be analysed and reported every year regardless of if the Scheme is used or not, to form a baseline which can be used to judge potential impacts associated with the use of the augmentation Scheme including reductions in groundwater level and impacts on the flow regime. The schedule will form part of the licence and will apply to current and any future licence holders. 26

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

The condition is necessary to monitor the relationship between the hydrological regime of the Candover stream and potential changes to the ecology, specifically abundance and diversity of invertebrate and macrophyte communities.

Whilst, the monitoring locations at Borough Bridge and Abbotstone are within the SAC and are characteristic of the general catchment and broad pressures, they do not represent the entire catchment. Potential impacts of augmentation on the ephemeral reaches of the catchment will not be detected.

For that reason an additional site will be added to the schedule to monitor for macroinvertebrates and macrophytes at a point yet to be defined, upstream of The Grange Lakes.

WFD Sustainability In order to meet our obligations under the Water Framework Directive (WFD), when determining applications for water resources licences, we must not:

• deteriorate water body status, including deterioration of individual quality elements; • compromise the implementation of improvement measures. These are described in the River Basin Management Plans (RBMP) to ensure we aim to achieve good status, or good potential, in water bodies; • compromise the achievements of protected area objectives (SAC, SPA and Ramsar sites). These are described in the Annexes of the RBMPs.

In the Part 1 report, section 9 explains how we have assessed these obligations for the renewal of the Candover Scheme licence. Analysis of the tests used to check WFD compliance for both surface water and groundwater, shows that there is not likely to be any risk of deterioration as a result of using the Candover Scheme and use of the scheme will not compromise the stated aim of achieving good status by 2027.

This analysis has considered the Candover Brook surface water body as well as the River Itchen and River Test Groundwater units.

Conclusions relating to Environmental Sustainability In order to renew the Candover licence we must show that it meets our test of Environmental Sustainability.

The analysis above shows that (provided all of the above conditions are applied to the licence; and the actions carried out), the licence can be shown to meet that test. Hence, we recommend that all of the above conditions be added to the licence, to capture and enable the conclusions of a great deal of work between us, NE and stakeholders to stand.

Justification of need When constructed, the purpose of the Candover Scheme was to support downstream Water Company abstractions by putting additional water into the River Itchen to provide better dilution of effluent and enable abstraction to continue. The Scheme also provided a benefit to other abstractors by allowing them to continue abstracting with no restrictions in dry periods. Abstractors benefitting from use of the Scheme paid additional supported source fees to the Environment Agency in recognition of this benefit.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Restoring a natural ecosystem function, based on natural environmental processes is required (Mainstone et al, 2016). In this context, it is not desirable to operate the Candover abstraction to counter or offset the damaging the effects of over-abstraction, climate change, excessive fine sediment, lack of habitat in favourable condition, and other pressures. In 2007, Natural England advised the Agency in response to our RoC work, “Natural England views the augmentation schemes as a short-term mitigation measure and not as a sustainable long term solution.” (Natural England, 2007). This is more expressly of concern when operation of the Candover augmentation has in itself both negative and positive physio-chemical and ecological effects.

The addition of pumped groundwater water to the upper reaches of the Itchen through operation of the Candover abstraction reduces the naturalness of the river. Naturalness is a feature of many habitats used to assess their ecological or nature conservation value (Ratcliffe, 1977). Artificial augmentation of flows may be considered as reducing the naturalness of the river and an unsustainable method of masking other damaging impacts. A system that requires intervention of that nature in order to achieve ecologically-based flow targets cannot by definition be a self-sustaining one.

Further consideration of the ecological ‘need’ for flow augmentation in the Candover must include reference to the concept of site integrity. The EC guidance document ‘Managing Natura 2000 Sites’3 considers the concept of site integrity at 4.6.3 and states that ‘A site can be described as having a high degree of integrity where the inherent potential for meeting the site conservation objectives is realised, the capacity for self- repair and self-renewal under dynamic conditions is maintained, and a minimum of external management is required’.

Bearing in mind Natural England (2016) have confirmed to the Agency as part of this assessment process, that the Candover licence is not directly connected with or necessary to the management of the River Itchen SAC (a test of the Habitats Regulations, 61(1)(b)), saying, “Natural England remains of the opinion that this type of abstraction in the headwaters of a designated river valley, combined with river augmentation, is not an alternative to, nor is it a necessary part of a sustainable abstraction regime and is not necessary for the conservation of the designated sites.” In that context there can be no justification for running the scheme for ecological ‘benefits’ in the long term.

A more sustainable approach would be to manage the wider abstraction and management regime of the Candover to reduce or avoid having to operate the Candover licence to augment surface water flows. Re- balancing the abstraction regime to restore a natural flow regime, with natural variability, is required to sustain natural processes that shape the form and function of the Candover Stream and the chalkstream biotope. Only then will the abstraction regime be sustainable. A step-change in effort to restore a natural flow regime is imperative if the ecological interests are ever to achieve favourable condition. Such an approach would be preferable for a number of reasons than attempting to justify operation of the Candover abstraction on the grounds of environmental support or enhancement.

However, restoring a more natural flow regime will take time. We will instigate an investigation into the abstraction licences that effect the Candover sub-catchment in the next NEP. That is likely to conclude in 2025, and any actions that arise from that will be implemented thereafter. In the meantime, the impacts and risks to the Candover from those licences will continue unabated.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

To counter the risk from those existing abstraction licences, we will retain the Candover licence but in a reduced form, with the capacity to augment river flows only in the event it is needed for ecological support, and only for so long as the risks from the existing abstraction licences remain as they are.

In that respect it is a ‘safety-net’, or insurance policy, should the Environment Agency and Natural England agree it is needed at any particular time whilst the effects of other extant licences remain in place. This is a short-term measure - we will time-limit the licence to 2022 to review the ‘need’. It is possible the need will remain until the NEP investigation is complete and actions implemented i.e. beyond 2025. That perceived need will be reviewed in 2022.

We do not foresee augmentation being part of the long-term solution.

Efficient use of water Efficient use of the Candover Scheme can be secured by minimising the occasions when it needs to be used and when it is in use, only using the minimum water possible to provide environmental support.

To ensure that any leakage from the pipeline is detected, flows are measured as they leave each borehole site and are also recorded at the outfall. Regular checks will detect any problems of leakage from the pipeline which could then be addressed.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

APPENDIX A – Summary tables from Part 1 Report The following four tables (8a to 8d) have been taken from the Part 1 report, and describe the hydrological changes from use of the existing Candover licence in more detail.

Magnitude of impact Duration of impact Frequency of impact

Candover Reduction in autumn and winter peak flows Low level impacts could upstream of depending on prevailing conditions and actual prevail for 6 – 18 months Grange Lakes use of scheme depending on prevailing conditions and actual use Alone impact - As much as - 50% in upper of scheme. reaches High impacts only Historically scheme only In-combination - not assessed in detail as flows expected to last for a few likely to be used once in are naturally very variable. In rare events, acting weeks. 10 years. with other licences, impacts can be as high as -50 to -100% with other abstractions thought to have Current licence allows a far more significant effect scheme to be used in consecutive years and Candover Maximum impact: Impacts from Scheme several times in a downstream of likely to fall below 1% sequence of years. Grange Lakes -5 to - 10% alone at Borough Bridge within 12 months, and only exceed 2-3% for - 10 to - 20% around Abbotstone several months

-25% in combination during high flow periods at Borough Bridge

-25% to - 65% at Abbotstone and can be higher during extreme events

The drawdown from the groundwater augmentation may decrease the winter Q10 flow.

River Alre Maximum impact: Impacts from Scheme likely to fall below 1% -2% to -3% alone within 12 months

-10% In combination during high flow periods

Upper Itchen Maximum impact: Impacts from Scheme likely to fall below 1% -1.5% Alone within 3 - 4 months

-6% In combination Cheriton Stream Not discernible N/A

Table 8a taken from Part 1 report) Summary of Impact on River flows after Candover Scheme has been turned off.

Magnitude of impact Duration of impact Frequency of impact

Candover Pattern of flow/no flow relatively unaffected. Impacts up to 18 months above Grange maximum, typically lasting Historically scheme only Lakes Potential of a delay of several weeks in spring head no more than 1 year likely to be used once in reaching maximum winter position and spring head 10 years. may be up to 1.75km lower than expected, although typically 250 - 500m. Current licence allows scheme to be used in consecutive years and

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River Alre Pattern of flow/no flow unaffected. Impacts typically lasting no several times in a more than 6 months sequence of years. Streamhead likely to move by up to 250m upstream Table 8b taken from Part 1 report) Impact on ephemeral stream-heads after scheme has been turned off.

Magnitude of impact Duration of impact Frequency of impact

Candover Stream Groundwater levels may be reduced by Impacts greater than 1m will persist in up to 3m in the upper Candover Valley the upper valley for 6 - 12 months. Historically scheme only with reductions of the order of 0.2m at Smaller impacts of less than 0.5m may likely to be used once in Northington and 0.1m further last for 12 - 18 months. 10 years. downstream at Abbotstone Smaller impacts in the lower valley Current licence allows may persist for up to 12 months from scheme to be used in when use of the scheme stops consecutive years and several times in a River Alre Groundwater levels may be reduced by Impacts of up to 0.1m may persist for sequence of years. up to 0.1m up to 12 months from when use of the scheme stops

Table 8c taken from Part 1 report) Impact on areas of high groundwater level which may be linked to groundwater dependent terrestrial ecosystems

Magnitude of impact Duration of impact Frequency of impact

Upper Candover Stream already likely to be dry upstream of discharge N/A point so no impact likely whilst scheme in use.

Lower Candover +110% alone Up to 6 months Historically scheme only Use of the scheme is likely to cause flows to rise from likely to be used once in those expected to be exceeded 95% of the time to 10 years. flows only expected to be exceeded 5% of the time. In other words from what might be expected in a dry Current licence allows summer to flows expected in a wet summer. Flows scheme to be used in beyond what would naturally be expected would not consecutive years and be permitted under the terms of the existing licence several times in a sequence of years. The rate of rise permitted by the licence conditions matches the rate observed in the wet summer of 2012 and is not as steep as that observed during exceptional events when rapid recharge naturally starts in October as observed in 1993.

Upper Itchen +10% alone Up to 6 months

+ 9 % in combination with all other abstractions and discharges from watercress beds. The underlying negative impacts of abstraction offset the positive influence on flows to make the increase in flows in- combination with other licences smaller than the increase in flows if the scheme was acting on its own Table 8d taken from Part 1 report) Impact of augmentation discharge on River Flows

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APPENDIX B - Summary of ecological conclusions of the existing Candover licence from Part 2 report

Our Part 2 conclusions for the River Itchen SAC are summarised in Table 7.1 below. Is there a likely significant effect from the During use of the scheme, After use of the scheme, the During and after use of the existing Candover licence on the River the discharge of colder water residual negative impacts on scheme, lowered groundwater Itchen SAC? into the Candover Stream river flow. levels and delayed with increased flows and groundwater recovery in the velocities. chalkstream headwaters. In- In- alone alone alone In-combination combination combination Compounded short-term ecological responses (characterised by the macrophyte and macroinvertebrate communities) becoming prolonged change, yes no yes yes yes yes with possible chronic effects, and reduced resilience and ability to recover.

Impacts on White-clawed crayfish with compounded short-term effects becoming prolonged change, with reduced resilience and ability to recover, (accentuated by the yes no yes yes no no existing isolated nature and inherent vulnerability of this population), and possible chronic population-level effects. Changes to the spatial extent and ecological condition of the ephemeral winterbourne reaches of the upper Candover Stream n/a n/a n/a n/a yes yes

Our Part 2 conclusions for the River Itchen SSSI are summarised in Table 7.2 below. Is there a likely negative effect from During use of the scheme, the After use of the scheme, the During and after use of the the existing Candover licence on the discharge of colder water into residual negative impacts on scheme, lowered groundwater River Itchen SSSI? the Candover Stream with river flow. levels and delayed increased flows and velocities. groundwater recovery in the chalkstream headwaters. In- In- In- alone alone alone combination combination combination Assemblages of breeding birds (waders and passerine species) of lowland open waters and their no no no no uncertain uncertain margins

Floodplain fen (lowland) ; Lowland Mire Grassland And Rush Pasture ; Lowland neutral grassland ; Lowland wet neutral grassland ; Lowland no no uncertain uncertain uncertain uncertain wetland including basin fen, valley fen, floodplain fen, water-fringe fen, spring/flush fen and raised bog lagg Rivers and Streams (characterised by the macrophyte and macroinvertebrate communities) yes no yes yes yes yes

As for the River Itchen SAC White-clawed crayfish population y no yes yes no no As for the River Itchen SAC

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

Our Part 2 conclusions for BAP habitats and species are summarised in Table 7.3 below. Is there a likely negative effect from During use of the scheme, the After use of the scheme, the During and after use of the the existing Candover licence on discharge of colder water into residual negative impacts on scheme, lowered groundwater BAP habitats and species? the Candover Stream with river flow. levels and delayed groundwater increased flows and recovery in the chalkstream velocities. headwaters.

In- In- alone alone alone In-combination combination combination Changes to the spatial extent and ecological condition of the n/a n/a no yes yes yes ephemeral winterbourne reaches of the River Dever and River Wey. Note that the conclusions for all other BAP habitats and Species are the same as presented in Tables 7.1. and 7.2. above, for the River Itchen SSSI and SAC

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

APPENDIX C: Background information.

Our Review of Consents process (RoC) of the Candover licence in 2005-2007:

The Review of Consents Appropriate Assessment (2005) concluded that it could not be shown that the Candover Scheme would not have an adverse effect on the integrity of the SAC both alone or in-combination with other permissions. This conclusion applied to the interest features:-

 White-clawed crayfish (Austropotamobius pallipes);  Water course of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation (subtype 1 : river on chalk substrate) (commonly referred to as the Floating Ranunculus habitat);  Southern Damselfly (Coenagrion mercuriale);  Atlantic salmon (Salmo salar).

That work also concluded that the Candover Scheme, alone and in-combination, could be shown not to adversely affect site integrity for three particular SAC features: - Otter (Lutra lutra); Bullhead (Cottus gobio); and Brook lamprey (Lampetra planeri).

Consequently, the Environment Agency determined in what we called our RoC Stage 4 Site Action Plan (2007), that the licence should be modified (not affirmed or revoked), in order to remove the risk to site integrity, and prescribed specific licence changes necessary to allow the outcome to be reached. Those licence changes, along with habitat works to be secured through the then Reg 51(3) (now Reg 64), would secure certainty that the licence could be shown to not adversely affect site integrity, both alone or in-combination with other abstraction licences. The proposed licence changes were made in 2015, and over half of the habitats works have now been completed, with funding secured to proceed with further work, subject to landowner approval.

The way that the Scheme can be used under the terms of the current licence is heavily constrained by licence conditions imposed in 2015 which ensure that:-

 Annual abstraction has been reduced to a maximum total of 3,750 Ml from the previously licensed total of 5,000 Ml.  The Candover Scheme can only be used when flows in the main River Itchen as measured at Allbrook and Highbridge fall below 240 Ml/d.  Use of the Scheme has to be gradually increased and decreased which means that it takes several weeks before the full output of the Scheme is discharged.  Use of the Scheme cannot be allowed to cause flows in the Candover Stream, as measured at Borough Bridge, to rise above the maximum that could be expected for that time of year, for five consecutive days.

What has changed since our 2005 RoC Appropriate Assessment?

1. Southern Water selected the Candover Scheme as their preferred option in their WRMP (2009 and 2014) to restore their supply/demand balance in response to our changes to their Itchen Otterbourne

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

licence. Consequently, Southern Water carried out comprehensive modelling and assessment to inform their WRMPs and accompanying SEA and HRAs. In summer 2015 the Company initiated a Candover Technical Working Group, to work with statutory bodies, NGOs and stakeholders, to increase scrutiny and improve modelling of risks associated with use of the licence. All of that work post-dates and exceeds the work we did in our 2005 RoC process. The new information has informed our latest thinking.

2. In 2011 we carried out extensive test-pumping of the Candover augmentation scheme. That was supported by a comprehensive programme of hydrological and ecological monitoring. This included monitoring of the population of White-clawed crayfish by the Hampshire & Isle of Wight Wildlife Trust. The comprehensive report they produced, in collaboration with the Environment Agency, (in 2012) highlighted concerns and presented a number of recommendations to resolve these.

3. In 2015 we refined our Test & Itchen Groundwater Model, and carried out further modelling assessments of the hydrological effects of the Candover scheme.

4. The Joint Nature Conservation Committee (JNCC) and the conservation agencies, including Natural England (NE), published CSMG (Common Standards Monitoring Guidance) in January 2014. Locally, we agreed with Natural England to adopt a phased approach to implementing the new targets that arose from CSMG. Although we are NOT currently applying the CSMG flow targets, but have committed to working with Natural England to consider the evidence for adding the Review of Consents Itchen-specific, bespoke, ecologically-based target flow regime to the CSMG targets in an amalgamated form, by 2021. However, for the sake of transparency and future-proofing our current work, we have considered what the effects of the Candover licence would be if the CSMG flow targets are applied in the Itchen now.

5. In the current assessment, we have taken the opportunity to consider effects against the locally derived, ecology-based flow targets we determined in our 2005 RoC process. Compliance with those requires a degree of retrospective flow analysis, so at the time we developed those targets we could only look at the historic record. For the purposes of this current assessment we have now been able to assess compliance since they were developed. Similarly, we have carried out analysis using the CAMS EFI flow analysis tool to better effect than was possible in 2005.

6. At the time of our RoC (2005), Natural England endorsed many of our decisions for the River Itchen SAC, but withheld formal agreement to our decisions specifically relating to the Candover abstraction licence. Now the licence is up for renewal, and it is Agency policy to (re-)apply the tests of the Habitats Regulations, we have closely engaged Natural England in this process to ensure this time our conclusions fully reflect their advice.

7. Natural England’s latest SSSI Condition Assessment (May, 2015) has further enhanced our understanding of the ecological status of the Candover.

8. Since 2005, there has been increased effort of ecological monitoring by third parties culminating, for example, in the publication of Riverfly monitoring data for the Candover Stream and upper Itchen catchment, in 2016 by both the Wessex Chalkstreams and Rivers Trust and the Salmon & Trout Conservation UK. 35

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

9. Over the same period, there has been increasing interest in and concern for chalkstreams, in particular the River Itchen, as evidenced by the WWF State of England’s Chalk Streams report (2014). We intend to invite the views and advice of local river owners and users, in particular those in the Candover catchment, in the renewal process (in addition to the statutory, formal public consultation period) to inform our final decision.

10. On 24th June 2016 two major groundwater abstraction licences were revoked at Fobdown. These licences permitted around 14 Ml/d of water to be abstracted from the Chalk aquifer for the purpose of watercress growing. At least 95% of the abstracted water had to be returned to the Candover Stream. This significant change in hydrological conditions in the catchment has substantially affected our assessment of the in-combination impact of the Candover Scheme licence, compared to our RoC assessment in 2005.

11. The existing licence, which is proposed for renewal, has already been subject to prior assessment under the Habitats Regulations, in 2005. However, the driver for that, and therefore the scope of the work, was purely the Habitats Regulations. In order to comply with our statutory duties and policies, the assessment of the renewal of this licence has considered wider environmental risks, for example to the River Itchen SSSI, and priority habitats and species, as well as to the River Itchen SAC.

Candover abstraction licence (SO/042/0031/026) renewal 2016 FINAL REPORT 11 August 2016

APPENDIX D: References

As both the owner and operator of the Candover abstraction licence and associated augmentation scheme, and also the environmental regulator and Competent Authority determining the permit renewal, this may be viewed as an unusual situation. We intend to make an application to renew the licence in summer 2016, allowing time for the licence to be renewed before it expires on 31st December 2016. In accordance with our standard procedures, the recommendation on renewal of the licence will be determined by our National Permitting Service (NPS) with the final decision offered to the Secretary of State for sign off.

In determining our final conclusions we have conducted a thorough assessment of the hydrological and ecological risks and impacts. And identified licence conditions that would allow the licence to be renewed. Our evidence is presented in a series of four technical reports which provide the technical evidence. The four reports should be read together, in sequence.

Key References for this Final Report Part 1 – Describes the hydrological context (naturalised flow regime, and historic flow Hydrological regime); likely hydrological changes as a result of using the Candover Licence; Impact Analysis an assessment in-combination with other existing abstraction licences; and how the context may change in a number of possible scenarios. Part 2 – An assessment of the ecological risks and consequences of operating the Assessment of Candover licence, against the River Itchen SAC and SSSI features and wider Ecological Risks biodiversity interests. It presents the existing ecological data and considers risks against a number of ecologically derived flow targets. Appropriate An Appropriate Assessment of adverse effect on site integrity of the River Assessment Itchen SAC, in accordance with Regulation 61, The Conservation of Habitats and Species Regulations, 2010. Table 6: listing key references which should be read in conjunction with this Final Report.

Managing Natura 2000 Sites – The provisions of Article 6 of the Habitats Directive 92/43/EEC).

Mainstone, C., Hall, R., and Diack, I. (2016) A narrative for conserving freshwater and wetland habitats in England. Natural England Research Report NERR064

Natural England (2016) Letter CAS.lr.2016, comments on draft EA Appropriate Assessment for the Candover licence renewal process.

Natural England (2007) Letter 10 May 2007. Ref B05/1-14/1-56, in response to the Agency’s RoC conclusions.

Ratcliffe, D.A. (1977) A Nature Conservation Review : The Selection of Biological Sites of National Importance to Nature Conservation in Britain

Wilby, R.L. (2010). An assessment of invertebrate-based target flows for the River Itchen, Hampshire. WWF-UK.

End.