Cambridge Water Final Drought Plan October 2018 South Staffs Water – Cambridge Region Drought Management Plan Table of Contents List of Figures and Tables ......................................................................................................................... 5 Executive Summary .................................................................................................................................. 6 1. Introduction ...................................................................................................................................... 8 1.1 Overview of the Process ........................................................................................................... 8 1.2 The Cambridge Region Drought Plan ....................................................................................... 9 1.3 Background to Cambridge Water ........................................................................................... 11 2. Consultation on the Drought Plan .................................................................................................. 13 2.1 Pre consultation ..................................................................................................................... 13 2.2 Consultation on the Draft Plan ............................................................................................... 16 3.1 Supply Demand Balance Position ........................................................................................... 19 3.2 Levels of Service – Frequency of Restrictions ........................................................................ 21 3.2.1 Compensation .................................................................................................................... 21 3.3 Deployable Output ................................................................................................................. 22 3.4 Leakage Control ...................................................................................................................... 22 3.5 Water Efficiency ..................................................................................................................... 23 4 Drought Scenarios .......................................................................................................................... 24 4.1 Historic Droughts .................................................................................................................... 24 4.1.1 1920s Drought Sequence ................................................................................................... 27 4.1.2 1972‐77 Drought Sequence ................................................................................................ 27 4.1.3 1988‐93 Drought Sequence ................................................................................................ 27 4.1.4 1995‐98 Drought Sequence ................................................................................................ 30 4.1.5 2003‐07 Drought Sequence ................................................................................................ 30 4.1.6 2011‐12 Drought Sequence ................................................................................................ 34 4.2 Drought Scenarios .................................................................................................................. 34 4.2.1 A Short Duration Drought .................................................................................................. 34 4.2.2 A Medium Duration Drought .............................................................................................. 36 4.2.3 A Long‐term Drought .......................................................................................................... 38 5 Drought Control Rules ‐ Triggers and Actions ................................................................................ 43 5.1 Groundwater and Rainfall Monitoring ................................................................................... 43 5.2 Drought Indicators .................................................................................................................. 46 5.3 Drought Triggers ..................................................................................................................... 46 6 Drought Management Actions ....................................................................................................... 52 6.1 Overview................................................................................................................................. 52 6.2.1 Leakage Reduction ............................................................................................................. 53 1 South Staffs Water – Cambridge Region Drought Management Plan 6.2.2 Temporary Water Use Restrictions .................................................................................... 53 6.2.2.2 Activities Covered by Restrictions ...................................................................................... 54 6.2.2.3 Implementation of Restrictions .......................................................................................... 55 6.2.2.4 Phased Introduction of Restrictions ................................................................................... 56 6.2.2.5 Concession and Exemptions ............................................................................................... 57 6.2.2.6 Communications ................................................................................................................. 59 6.2.2.7 Ordinary Drought Orders (Non‐Essential Use Restrictions) ............................................... 59 6.3 Supply‐side Actions ................................................................................................................ 61 6.3.1 Deployable Output ............................................................................................................. 61 6.3.2 Maintaining Existing Sources .............................................................................................. 62 6.3.3 Bulk Supplies....................................................................................................................... 63 6.3.4 Drought Orders and Permits .............................................................................................. 63 6.3.5 Potential Drought Permit Sites ........................................................................................... 63 6.3.6 Emergency Drought Orders ................................................................................................ 65 7 Environmental Impacts .................................................................................................................. 66 7.1 Environmental Assessment .................................................................................................... 66 7.2 Supply Side Option Assessment ............................................................................................. 69 7.2.1 Option S1: Re‐commission Fleam Dyke 12 Borehole ......................................................... 70 7.2.2 Option S2: Re‐commission Croydon PS .............................................................................. 71 7.2.3 Option S3: Re‐commission Kingston PS .............................................................................. 72 7.2.4 Option S4: Re‐commission St Ives PS ................................................................................. 72 7.3 Statutory Designated Sites ..................................................................................................... 73 7.4 Habitats Regulations Assessment .......................................................................................... 73 7.5 Strategic Environmental Assessment ..................................................................................... 74 7.6 NEP Investigations .................................................................................................................. 77 7.6.1 Previous Investigations ....................................................................................................... 77 7.6.2 River Granta ........................................................................................................................ 77 7.6.3 Nine Wells Local Nature Reserve (LNR) & Hobson’s Brook ................................................ 78 7.6.4 Cherry Hinton Brook ........................................................................................................... 78 8 Drought Monitoring Plan ............................................................................................................... 79 8.1 Overview................................................................................................................................. 79 8.2 Baseline Monitoring ............................................................................................................... 79 8.2.1 Meteorological and Hydrometric Monitoring .................................................................... 79 8.2.2 Ecological Monitoring ......................................................................................................... 80 8.3 Enhanced Monitoring Plan ..................................................................................................... 80 2 South Staffs Water – Cambridge Region Drought Management Plan 8.3.1 Supply Side Options ...........................................................................................................