THE GRANTHAM URBAN RIVER AND WETLANDS PLAN: An overview of issues and opportunities in the River Witham corridor THE PURPOSE OF THE PLAN The GRANTHAM URBAN RIVER AND WETLANDS PLAN identifes issues and brings together the plans, ideas and aspirations of a diverse range of groups and organisations with an interest in the River Witham and the riverside through Grantham. It is not an Environment Agency Plan, instead it is intended to be a catalyst for the development of new partnerships to deliver mutually benefcial projects and encourage the pooling of resources to achieve greater results. Delivery is ongoing and groups and organisations are welcome to bring forward new projects at any time. OVERARCHING OBJECTIVES Objective 1. River Habitat Enhancement and Restoration There is huge potential for instream and marginal habitat improvements. New gravel rifes, woody habitat and marginal wetlands will greatly beneft wetland biodiversity and improve the Ecological Status of river, a requirement of the Water Framework Directive. Particular emphasis should be placed on Safeguarding Protected and Notable Species, e.g. white-clawed crayfsh, water voles, otters, brown trout and bats, aided by the production of distribution maps. Some outline opportunities have been identifed on the Plan Map, although further, more detailed, survey work will be required to determine the full range of opportunities. Some improvements could be implemented in the short term, but if it is feasible to remove some of the structures, e.g. the low weirs (see Objective 2), then in-stream habitat should be planned in conjunction with these schemes to ensure that they function under the new hydrological conditions. Habitat enhancement schemes must be carefully designed to ensure that they do not increase food risk. Objective 2. Improving Hydromorphology and Fish Passage There are numerous weirs and sluices along the river that, to varying extents, impound the watercourse, limiting the morphological and ecological potential of the river and obstructing fsh movement. Fish passage issues need to be addressed at all these structures. Fish passes can be retro-ftted to some structures, but where possible structures should be removed altogether which would not only allow fsh movements, but also restore the natural bed gradient. Coupled with in-stream habitat enhancements, e.g. channel narrowing and gravel introduction (see Objective 1), this would greatly increase the ecological value of the river, with the added beneft of reducing food risk by increasing foodplain capacity. Objective 3. Improving Water Quality by Tackling Potential Pollution Sources Good water quality is essential to the health of the river environment. Issues associated with road run-of (either directly in to the river or via tributary streams e.g. the Mow and Barrow Becks), foul and combined sewer discharges and contaminated land must be addressed to ensure the success of Objectives 1 and 2. Objective 4. Tackling Invasive Non-Native Species (INNS) Invasive Non-Native Species (INNS), e.g. Himalayan balsam, knotweed species and giant hogweed, are degrading the quality of riverside habitats, and species, such non-native North American Signal Crayfsh, could adversely afect native species populations in the future. A survey and mapping exercise should be undertaken to identify the extent and locations of INNS, followed by the development and implementation of a strategic plan to tackle the identifed issues. Anglers and contractors undertaking in-river works should be encouraged to exercise appropriate biosecurity measures to prevent the introduction of non-native species. There is an opportunity for volunteers, e.g. RiverCare and angling clubs, to participate in the survey work and the practical management of some species e.g. Himalayan balsam. Objective 5. Developing Riverbank Management Plans Public open spaces linked by riverside paths make the River Witham through Grantham unusually accessible and this experience is enjoyed by many people. The successful RiverCare Group shows how much local people value the river. However, initial consultation on this plan identifed lack of bank management, littering and grafti to be ongoing issues and a lack of riverside seating was also highlighted. There is particular concern about how the river banks are being managed adjacent to public paths, in particular the amount of bramble encroachment. Riverside trees are also an issue. The costs of regular management/maintenance can be high so it is recommended that South Kesteven District Council, RiverCare and Environment Agency explore the issues and develop a prioritised Riverbank Management Plan which, in addition to bramble management, addresses tree protection, maintenance and planting, and measures for tackling invasive non-native species (see Objective 4). This would also be an opportunity to explore the littering, grafti issues and need for more seating. HOW TO EXPLORE THIS MAP This map is a layered pdf: click on the “Layers” icon ( )on the left side of the Adobe Acrobat or Adobe Acrobat Reader window REACH 4. MANTHORPE MILL TO THE A607 SYSTON ROAD to show the individual layers, Section 4.2. Belton House Weir (16a) and ‘Gothick Ruin’ cascade (16b) to A607 which can be turned on and of to 1. The bed gradient improves immediately downstream of the Belton House structures (16a and 16b) and weir, but from just beyond the road bridge, where there is a deep pool and rife, the river slows again through a heavily-shaded channel through enable you to explore the map woodland before fowing under the A617. There is fallen deadwood in the channel which could be augmented, but the slow- fowing nature of the river makes enhancement of this section a low-priority. with greater clarity. 16a 16b Section 4.1. Manthorpe Mill (15a) to Belton House Weir (16a) and ‘Gothick Ruin’ Cascade (16b) 1. For the majority of this section the river runs through Belton Park and there are no built food defences. 2. The felds either side of the river downstream of Manthorpe Mill are cattle-grazed and the cattle have unrestricted access into and across the channel BELTON HOUSE causing damage and sediment input. Consider installing fencing and a formal cattle drinker/crossing to reduce fne sediment inputs caused by cattle poaching. 5IFPXOFSPGA5IF-PEHFIBTVOEFSUBLFOTPNFSJWFSESFEHJOHBOEXFFEDVUUJOHBEKBDFOUUPIJTQSPQFSUZBOEUIFFYDBWBUFETFEJNFOUIBTCFFOQMBDFE behind timber board revetment which is now collapsing. There is an opportunity to rectify this using faggot/coir revetment and to narrow the river to improve the fow and reduce sedimentation. 5IFNPVUIPGUIFEJTDIBSHFDIBOOFMGSPN.BOUIPSQF4FXBHF5SFBUNFOU8PSLT PQQPTJUFA5IF-PEHF JTPCTUSVDUFECZGFODJOHXIJDITIPVMECFSFNPWFE to improve conveyance. 5. The river enters Belton Park via a recently modifed river gate to prevent fallow deer access upstream. There is a signifcant build-up of foating debris against the gate which is afecting conveyance. The gate requires further modifcation or regular cleaning. 6. The upstream section through Belton Park ofers signifcant opportunities for enhancement. Upstream of the outfall from the ornamental lakes the channel would beneft from gravel introduction and the addition of woody habitat to create fry and invertebrate refuges and narrow the channel to improve fows and encourage natural cleansing of the gravels. Additional trees should also be planted to provide shade. Downstream of the lake outfall the river widens and the fow slows. Fine sediment is settling out and encouraging the growth of marginal wetland vegetation. Consider hinging and pinning bankside trees and/or installing fow defectors to help consolidate the sediment and maintain increased scour and bed cleansing all year round. A comprehensive river enhancement scheme should be developed in consultation with the National Trust, taking into account know protected species issues XIJUFDMBXFEDSBZöTIBOEXBUFSWPMFT BOEQPUFOUJBMBSDIBFPMPHJDBMJNQBDUT"TUIFSJWFSFOUFSTUIFA8JMEFSOFTTUIFJNQPVOEJOHFòFDUPGUIFXFJST downstream takes full efect. The river is wide, silty and heavily shaded and is in need of signifcant improvement, including increasing light penetration to the channel to encourage colonisation by marginal wetland vegetation. This section of the river is part of the formal gardens at Belton House so careful consideration needs to be given to the scheme design to ensure that the enhancements, including a suitable fsh pass, are sympathetic to the historic setting. "UUIFCPUUPNPGUIFTFDUJPOUIF#FMUPO)PVTF8FJS B BOEA(PUIJDL3VJODBTDBEF C IBWFBTJHOJöDBOUJNQPVOEJOHFòFDU XIJDIJTBQQBSFOUGPSPWFS NFUSFT BOEBSFBCBSSJFSUPöTIQBTTBHF"MMUIFøPXXBTCFJOHEJWFSUFEPWFSUIFA(PUIJDL3VJOTDBTDBEFBUUIFUJNFPGUIFTVSWFZ +VOF REACH 3. WYNDHAM PARK WEIR (10) TO MANTHORPE MILL (15a, 15b) Section 3.4. Harrowby Mill Weir (13) to Manthorpe Mill (15a) BELTON PARK 1. Downstream of Harrowby Mill Weir the river is more rural in character although the adjacent land is still protected from fooding by built food defences. 2. Immediately downstream of Harrowby Mill Weir the dry left bank berm could be reduced in height to create a wet berm/wetland habitat. However, the trees on the bank/berm immediately adjacent to the weir should be retained as they are ensuring that the scour beyond the spillway is constrained. The extensive gravel beds downstream of the weir could be further enhanced. 3. Beyond here the channel divides and the river is impounded by a rock weir (14a) on the main channel and a narrow sheet-piled weir (14b) on the adjacent bypass channel. The bypass