Sankey Catchment Action Plan Appendices Appendix 1: Watercourse Profiles 1.1 Whittle Brook Whittle Brook is an isolated river with no hydrological link to other water bodies in the Sankey Catchment and, as such, receives no pollution from upstream sources. Whittle Brook rises in a natural channel in a semi-urban landscape close to Sutton Manor and Clock Face. This area is also known for its coal mining with the historic Sutton Manor and Clock Face collieries in close proximity. As the river traverses towards the Mersey it flows under the M62, A57 and through the urbanised area of Great. Many of the issues surrounding the water quality and physical form of Whittle Brook can be related to the urban environment. Whittle Brook joins Sankey Brook in an open channel immediately prior to confluence with the Mersey Estuary. As the map above demonstrates, there are issues with phosphate in the headwaters of Whittle Brook. At the moment our understanding of the sources of the phosphate are limited, with potential for misconnections from urban areas such as Clock Face but also for recreational and agricultural land to be impacting on water quality. Modelling suggests that around 60% of phosphate in Whittle Brook can be attributed to arable farming. Further research is needed to identify the potential sources of pollution in and around the head waters but it would appear that a farm advice campaign, with the emphasis on pollution prevention and best practice of water management, would assist in reducing pollution to Whittle Brook. At present it is not thought that the historic mining has resulted in any acute water quality issues but there is always the possibility of issues arising as changes in groundwater occur. Currently, Union Brook and Whittle Brook both receive drainage form the former colliery. This requires a watching brief. Further down the catchment, the landscape becomes more urban and there is a greater risk of diffuse pollution from urban infrastructure but also greater scope for misconnections from domestic properties. Modelling suggests around 32% of phosphate is related to urban diffuse pollution. Major developments around Omega south have led to discharging to Whittle Brook and Barrow Brook. Much of Great Sankey, north Penketh, Lingley Mere and Whittle Hall areas are on separate sewer systems and in the past there have been several reports of misconnections causing water quality issues. These locations investigated for diffuse pollution and targeted as part of a misconnections campaign. Once the main sources of diffuse pollution are identified, the possibility of retro-fitting SUDs into existing green space should be investigated to reduce pollution entering Whittle Brook. There could also be opportunities to install street trees to help reduce pollution entering the brook as well as providing ecological, climate change and aesthetic benefits to local communities. Whittle Brook has been physically changed and modified as the land around it has developed, particularly around Great Sankey. While some of these modifications are required for flood defence reasons, there are stretches of the brook where the removal of timber revetments and hard banks would improve the physical form of the river and improve ecology. These are indicated on the map by a green diamond. There are also issues with invasive species in and around the riparian environment, which require a catchment approach to management and eradication. In terms of flood risk, the Whittle Brook Flood Risk Management Strategy (FRMS) flood cell extends from Lingley Green at its upstream end to Great Sankey, around 350m upstream of the railway culvert. The FRMS flood cell for Penketh Brook incorporates all of the flood risk area between Penketh Brook and Whittle Brook, including a length of the Whittle Brook upstream of the railway culvert. This reflects the primary risk of flooding from Penketh Brook in this area. Penketh Brook also poses a risk of fluvial flooding to the local community. Penketh Brook is a small watercourse that has reaches of natural channel and other reaches that are maintained in a modified channel. It flows from the rural area upstream of the A562 Widnes Road through the more urbanised area of Penketh, passing under the St Helens Canal and railway line in culvert before discharging into the River Mersey through an outfall culvert. Recent local flooding at Hall Nook by, what are believed to be, low order events has highlighted a lack of capacity through the long culvert under the St Helens Canal and railway line and very limited storage capacity in the field adjacent to the right bank. There is also a culvert under the A562, which can restrict high flows. There is a tidal barrier (flap valve) at the confluence of Penketh Brook with the Mersey, with the only influence of the tide being the duration for which the watercourse is tide-locked. The FRMS notes that these problems are also exacerbated by lack of capacity in the surface water drainage system. However, works were undertaken in 2012 by United Utilities (UU) which will have significantly alleviated the surface water risks arising from more frequent events. For Penketh Brook the FRMS preferred option was new linear defences; however economics have shown it would be difficult to secure central funding. This area is currently being reappraised by the Environment Agency, including the possible use of natural flood management. The FRMS recommended a Do Nothing option for Whittle Brook, as the risk of flooding was considered to be low, however this will require close monitoring in future years because of the possible impacts of climate change. 1.2 Sutton Brook Sutton Brook is the first of several rivers that feed into Sankey Brook. The water quality of Sutton Brook passes WFD standards but it has been physically altered over centuries of urban development. While it is not possible to return the river back to a natural state, there are a number of these alterations that can be removed and changed in order to improve the physical form of the river. These changes include the removal of bank reinforcement, removal of obstructions in the river channel, the re-opening of culverts, improving the channel profile and the installation of fish and eel passes at several locations (where removal of a barrier to migration is not possible). Such changes will improve in-river and bankside ecology but also align the flow of Sutton Brook and reduce the potential for flooding from the river. The naturalisation of banks will also help mitigate climate change by cooling the river and reducing run off reaching the brook. There are known issues with contaminated land near Watery Lane at the bottom of the Sutton Brook catchment. This contamination is unlikely to be resolved due to complex issues and as such the removal of hard banks in this section is unlikely as are further water quality improvements. There could also be opportunity to remove culverts between Colliers Moss Common nature reserve and Sutton brook, if there are no risks posed by contaminated land, and the culvert of a tributary and of Sutton brook that runs through Sherdley Park. Removing the culverts and naturalising the river in these areas would help filter and attenuate flows from these tributaries into Sutton Brook. There is also the opportunity to initiate a ‘slow the flow’ natural flood management approach to water management in the upper reaches of this river to reduce flood risk to downstream communities. 1.3 Hardshaw (Windle) Brook Hardshaw (Windle) Brook is typical of many water bodies; semi-urban and failing expected standards due to diffuse pollution from multiple sources.it is formed at the confluence of Windle Brook and Thatto Heath Brook below Canal Street. The location of the water quality sample point on Hardshaw (Windle) Brook provides us with an indication of where the diffuse issues may be coming from. Around 25% of phosphate in Hardshaw (Windle) Brook is attributed to agriculture. There is a need to carry out a rural pollution prevention/farm campaign offering land management advice and water management plans to land owners/manager. Installing buffer strips, shelterbelts and woody debris would also help slow the flow of water reducing flood risk downstream as well as improving water quality by reducing phosphate inputs and improving local habitat. Approximately 60% of phosphate in this water body is believed to come from urban sources and phosphate is currently failing water quality standards. Any issues with combined sewers in the catchment would likely be identified and rectified by United Utilities (with many improvements already made in previous AMP schemes) and much of the combined sewer network is in the lower section of the catchment where housing stock is olders. Water quality in the river is already 'moderate' before it reaches the area served by the CSOs. The housing to the north of the sample point, around Denton’s Green, Eccleston and Windle, is on a separate sewer system and as such pose the greatest risk of misconnections to Windle and Mill Brooks. These locations would be ideal for a misconnections campaign. At the same time, there are opportunities to use existing green spaces to install online SUDs systems/wetlands to attenuate and filter the water body as it moves downstream or to filter surface water drainage before reaching the water body. To undertake such measures requires partnerships with the local council, schools or other landowners who could benefit from a reduction in surface water charges if SUDs are used instead of traditional surface water discharges. Those parks, recreational grounds and schools close to the brooks include: • Eccleston Road Park (Windle Brook); • Windlebrook Crescent Open Space (Windle Brook); • Bleak Hill primary School (Windle Brook); • Lynton Way Play Area (Windle Brook); • De La Salle School (Mill Brook); • St Julies Catholic Primary School (Mill Brook); • Mill Wood / Mill Brook Wildlife Site (Mill Brook); • Dodd Avenue Playing Field (Mill Brook); • Railway Wood (Windle Brook); • Coleridge Avenue Open Space (Windle Brook); • Derelict/Vacant land at WA10 6LW (Windle Brook); and • Grassed land at the end of Windleshaw Road (Blocking access to Bishop Road) (Windle Brook).