King’s Sedgemoor and Aller Moor Water Level Management Plan – Parrett Internal Drainage Board Approved July 2010 King’s Sedgemoor and Aller Moor Water Level Management Plan Parrett Internal Drainage Board Approved July 2010 Contents 1. Approval of the Water Level Management Plan ........................................................... 3 2. Introduction .................................................................................................................... 4 2.1. Purpose of the Plan .................................................................................................. 4 2.2. Plan area .................................................................................................................. 4 2.3. Responsibility for preparation and implementation of the Plan .................................. 5 2.4. Consultation and Plan approval ................................................................................ 5 3. Hydrology, watercourses and infrastructure ............................................................... 7 3.1. Topography and soils ................................................................................................ 7 3.2. Water supply ............................................................................................................. 7 3.3. Drainage ................................................................................................................... 8 3.4. Asset management systems ..................................................................................... 8 3.5. The strategic context for water management ............................................................ 9 3.5.1. Catchment Flood Management Plan .................................................................. 9 3.5.2. Catchment Abstraction Management Strategy ................................................... 9 3.5.3. Lower Parrett & Tone Flood Management Strategy .......................................... 10 3.5.4. Parrett and Tone Channel Monitoring Project ................................................... 10 3.6. Watercourses .......................................................................................................... 10 3.6.1. Main Rivers ...................................................................................................... 10 3.6.2. IDB watercourses ............................................................................................. 10 3.6.3. Private ditches .................................................................................................. 10 3.7. Structures ............................................................................................................... 19 3.7.1. Structures controlling inflows ............................................................................ 19 3.7.2. Structures controlling outflows .......................................................................... 19 3.7.3. Structures controlling water levels within the area ............................................ 19 3.7.4. Gauge boards .................................................................................................. 28 3.7.5. Water level telemetry ........................................................................................ 30 3.8. Abstraction and other hydrological management issues.......................................... 30 3.9. Water quality ........................................................................................................... 31 4. Agriculture and other land uses ................................................................................. 33 4.1. Agriculture............................................................................................................... 33 4.2. Built development, services and transport ............................................................... 33 4.3. Recreation .............................................................................................................. 34 4.4. Fisheries ................................................................................................................. 34 Page 1 of 65 King’s Sedgemoor and Aller Moor Water Level Management Plan – Parrett Internal Drainage Board Approved July 2010 5. Nature conservation and archaeology ....................................................................... 35 5.1. Nature conservation interests ................................................................................. 35 5.2. Biodiversity Action Plans ......................................................................................... 37 5.3. Conservation management ..................................................................................... 37 5.4. Archaeology ............................................................................................................ 37 6. Constraints and impacts on adjacent ground ........................................................... 38 6.1. Works adjacent to Main River ................................................................................. 38 6.2. Works adjacent to IDB rhynes ................................................................................. 39 6.3. Private ownership of land and property rights ......................................................... 39 7. Current water management practices ........................................................................ 39 7.1. Current water level management regime ................................................................ 39 7.1.1. Current target water levels ............................................................................... 39 7.1.2. Contingency measures for drought ................................................................... 44 7.1.3. Raised Water Level Areas ................................................................................ 44 7.2. Current flood management regime .......................................................................... 47 7.2.1. Contingency measures for flooding .................................................................. 47 7.3. Current watercourse maintenance regimes ............................................................. 48 7.3.1. Environment Agency maintenance practices .................................................... 48 7.3.2. Parrett IDB maintenance practices ................................................................... 49 8. Objectives for water level management in the future ................................................ 50 9. Proposed water management practices..................................................................... 51 9.1. Continuation of current good practice ...................................................................... 51 9.2. Changes to water control infrastructure ................................................................... 51 9.3. Changes to target water levels ................................................................................ 55 9.4. Changes to operational procedures and responsibilities ......................................... 61 9.5. Changes to maintenance practices ......................................................................... 63 10. Unresolved matters ..................................................................................................... 64 10.1. Climate change impacts .......................................................................................... 64 11. Amendments agreed during the period of the Plan .................................................. 64 12. Review arrangements .................................................................................................. 64 13. Timetable of actions: King’s Sedgemoor and Aller Moor WLMP ............................. 65 Maps 1. Plan area 2. Arterial watercourses 3. Water control structures 4. Current areas with water levels held above normal pen level 5. Nature conservation sites 6. Archaeological sites and features 7. Water management for favourable condition on King’s Sedgemoor SSSI and Moorlinch SSSI 8. Flood zones within the Plan area 9. Location of proposed works for the Kings Sedgemoor SSSI 10. Location of proposed works for the Moorlinch SSSI 11. Future areas with water levels held above normal pen level Page 2 of 65 King’s Sedgemoor and Aller Moor Water Level Management Plan – Parrett Internal Drainage Board Approved July 2010 1. Approval of the Water Level Management Plan This Water Level Management Plan has been prepared by the Parrett Internal Drainage Board for the King’s Sedgemoor and Aller Moor area of the Drainage Board District. Contributions to the WLMP have been received from the Environment Agency, Natural England and others. Water Level Management Plan – General details Plan area King’s Sedgemoor and Aller Moor (Parrett IDB) King’s Sedgemoor SSSI SSSI(s) covered Moorlinch SSSI Region / Area Somerset Levels and Moors IDB lead officer Philip Brewin, Ecologist Approval of the Water Level Management Plan “I agree with the proposals and actions set out in this Water Level Management Plan and confirm the Plan will help achieve favourable condition for the Sites of Special Scientific Interest covered by the Plan.” Position & Name Signature Date Organisation Chairman – Peter Maltby Parrett Drainage Board Area Manager – Nick Gupta Environment Agency Area Manager – Mark Watson Natural England Page 3 of 65 King’s Sedgemoor and Aller Moor Water Level Management Plan – Parrett Internal Drainage Board Approved July 2010