Revised draft Water Resources Management Plan 2019 Statement of Response Appendix 7: Our detailed response to all non- questionnaire respondent comments September 3rd 2018 Appendix Respondent 7.1 Environment Agency 7.2 Natural England 7.3 Ofwat 7.4 Historic England 7.5 West Sussex County Council 7.6 Kent County Council 7.7 Hampshire County Council 7.8 WortHing & Adur Councils 7.9 Test Valley BorougH Council 7.10 New Forest National Park AutHority 7.11 Dover District Council 7.12 Canterbury City Council 7.13 New Forest District Council 7.14 Partnership for Urban SoutH Hampshire (PUSH) 7.15 Royal Society for tHe Protection of Birds (RSPB) 7.16 Salmon & Trout Conservation UK 7.17 National Farmers Union (NFU) 7.18 Kent Wildlife Trust and Sussex Wildlife Trust 7.19 Hampshire & Isle of WigHt Wildlife Trust 7.20 Arun & RotHer Rivers Trust 7.21 Wessex CHalk Streams and Rivers Trust 7.22 SoutH East Rivers Trust 7.23 Canal & Rivers Trust 7.24 SoutH West Water 7.25 Affinity Water 7.26 PortsmoutH Water 7.27 Wessex Water 7.28 West Country Water Resources Group 7.29 Mr CHris Lowe 7.30 Mr William Cutting 7.31 Tracey Crouch MP 7.32 Fawley Waterside Ltd 7.33 Little River Management and Barker Mill Estate 7.34 Isle of WigHt Rowing Forum 7.35 Arun District Council 7.36 World Wildlife Fund (WWF) Appendix 7.1: Environment Agency Information or changes SWS' Consideration of Response Changes Required to dWRMP Area of issue Issue and evidence Implications required Recommendation 1: Improve its approach to outage Southern Water has experienced high outage in three of its resource zones for the last two years that has resulted in or contributed to a dry year deficit in supplies. In its draft Southern Water have set out an outage recovery profile for specific sources that will be delivered during the remainder of AMP 6 and AMP 7. The outage allowance adopted thereafter has been based on a historic analysis of The outage methodology is detailed in appendix plan, the company has not demonstrated that it has made sufficient progress in addressing this issue, with high outage continuing to be forecast in the early years of the total and partial outage that is appropriate for unplanned events. F to Annex 3. Also see Annex 3 Section 8 for a planning period. It is not clear if the company has used recent observed outage data to inform its assessment of outage. Doing this will ensure that its forecasts of outage are high level summary of the appendix achievable, accurate and realistic. The company also states that it has followed the recommended UKWIR guidance to assess outage, but it is unclear in the plan if this is the This profile forms an updated outage allowance scenario reducing to 34.61 Ml by 2025 for a normal/dry year. This method is based on actual outage and schemes to reduce outage. The analysis we completed and presented case. It has not used its risk-based planning methodology to assess and forecast outage. This is out of line with the approach the company has taken across the rest of its in the draft Water Resources Management Plan will act as support for this approach, showing that based on historical analysis these levels of outage can be maintained. Furthermore a level of uncertainty is built into the model draft plan. It is unclear why the company has chosen to do this or what the implications of this are to the plan. If actual outage is higher than estimated in the plan, this poses a for outage that could be experienced whilst the outage recovery plan is being implemented. This will add more resilience to each of the water resource zones. The methodology will be detailed in an appendix to Annex 3. risk to the security of supplies in a dry year. The company should improve its approach to assessing outage, and describe what it will do to achieve further reductions to outage and show that outage does not contribute to or cause dry year deficits. R1.1: High outage The company has indicated high outage compared to WRMP14 outage allowance in its If the company has not The company should provide An outage recovery plan has been implemented for the remainder of AMP 6 bringing outage levels down to 76.30. The start of the plan (2020) will therefore see a higher level of outage allowance (76.30). A further reduction The outage methodology is detailed in appendix experienced Annual Reviews reporting for 2015/16 and 2016/17. This resulted in concerns to the assessed the outage further information on the outage in AMP 7 has been planned, bringing the levels of outage down to 34.61 by 2025. This profile has been adopted for one of the scenarios to be tested in the investment modelling. The profile in the plan thus follows the F to Annex 3. Also see Annex 3 Section 8 for a security of supply in the case of a dry year for 3 of the company’s water resources allowance adequately there assessment to demonstrate how planned outage recovery profile and is based on schemes that will be delivered by 2025. For 1:200 and 1:500 year droughts the approach post 2025 is to reduce the outage to the full outage levels maintained during the high level summary of the appendix zones. It is a concern that the company may not deliver its outage recovery plan and is a risk that the company these high outage events have 2006 drought and adding on the partial outage calculated for 2025 under the outage recovery plan (no partial outage data available for 2006 (29.45)) in order to get a total outage figure. The methodology will be detailed in hence start the WRMP19 plan period (2020 onwards) with higher levels of outage may again experience higher been incorporated into the an appendix to Annex 3. experienced than the draft WRMP19 suggests. outage than planned posing outage calculation. It should also R1.1 a risk to the security of provide some reassurance supply. around the recovery of outage to ensure that the planned outage allowance in WRMP19 is appropriate. UKWIR Outage The company states that it uses the UKWIR (1995) outage allowances for water If the company is not The company should fully explain The data required to follow the UKWIR (1995) guidance in it's entirety is unavailable. In light of this several approaches to outage were considered. Firstly a similar method used to PR14 was used, secondly a methodology The outage methodology is detailed in appendix allowance resources planning methodology. However, it is not clear whether this methodology has following the UKWIR (1995) and demonstrate that it has used based on a planned outage profile was used (detail of both approaches will be included as an appendix to annex 3). F to Annex 3. Also see Annex 3 Section 8 for a methodology (1995) been followed. In Annex 3 the company provides a summary output of the outage outage methodology it may and followed the correct Rather than over or underestimating outage allowance in the plan, the allowance will be based upon actual achievable outage and supported by the original methodology. high level summary of the appendix method used but it provides little detail as to the derivation of the estimates. be overestimating or methodology to calculate its An additional unpublished supporting document has been presented to the Environment underestimating the outage outage allowance. If this differs Agency which provides further information of the outage assessment. However, there is allowance in the plan. from the UKWIR (1995) outage still a lack of clarity about whether the methodology has been followed correctly. This could result in issues allowance methodology the The outage calculation in the plan is based on an outage allowance where the number that have been identified in company should fully outline how of sources increases the outage percentile as resilience increases. This is based on a the past two Annual Reviews the approach differs and justify linear regression graph, however, it is not clear how this has been calculated. of the WRMP14, where the reason for this deviation. The company has presented its outage allowance for each zone and provided a brief actual outage experienced The company has provided some R1.2 explanation of how it has calculated these figures. The company states that it re-ran the has been significantly higher data, however, it is not clear how existing UKWIR (1995) methodology as used in previous WRMP’s. than the planned outage the company has used the When reviewing the 2009 and 2014 WRMP it is not clear the assessment is in line with allowance, resulting in a risk UKWIR (1995) methodology to the UKWIR methodology. There is no mention of determining probability distributions for to security of supply in a dry develop its outage allowance magnitude, duration or frequency for sourceworks outage events or of a Monte Carlo year scenario. figures. The company should analysis (500 iterations recommended) to develop a single distribution which will feed fully outline the method used into the outage allowance calculation. and how historic data has been Furthermore, it is unclear whether the company calculates outage events for individual used. sources or sourceworks; UKWIR (1995) states that it should be outage events for sourceworks that are calculated. Outage allowance The company has used data from historical outage events and the number of sources in The outage allowance for The company should Under the new methodology Hampshire Kingsclere and Hampshire Southampton East still have zero full outage, this is because they currently have no outage.