Lower Witham River Corridor Habitat Plan

Draft Version II (17/01/2014) for External Consultation

Consultation Deadline 02/07/14

1. Introduction

1.1. The lower river Witham catchment area For the purpose of this plan the lower river Witham is defined as starting at Stamp End Lock in Lincoln and finishing at Grand Sluice in Boston which is the extent of the Witham before it becomes tidal. The lower Witham catchment has seven separate sub catchments, two of which are below the tidal limit. For the basis of this plan we are focusing on the main river Witham and up to the first structure on each of the sub catchments that join above Grand Sluice. The remaining sub-catchments will be addressed separately.

The landscape of the lower Witham catchment is predominantly agricultural with agricultural use on the land accounting for 88% of land use. Historically the lower Witham would have been a large fen fed by the upper Witham and various limestone springs flowing off the surrounding higher escarpments. During the roman occupation the first channel was dug to drain this fenland and aid navigation. Medieval records state that the Witham had tortuous meanders as it flowed towards Boston and over the last couple of centuries the more meandering river channel has been straightened, deepened, widened, impounded, embanked and strengthened using stone on the toe of the bank as part of fluvial engineering schemes designed to reduce flood risk, improve land drainage and to aid navigation. These modifications, together with catchment land management practices, have contributed to a decline in overall river corridor habitat quality in the catchment.

The lower Witham historically was one of the renowned match fishing venues in the 1970’s and commercially very important with anglers travelling from all over the country to fish it throughout the week bringing in angling related revenues to the area. Many local clubs sprang up to capitalise on this with angling clubs formed in Boston and Lincoln. Since water quality improvements have led to the cleaning up of our river systems, the match fishing catches have declined which has led to a general loss of local clubs as memberships levels drop leading to leases on the river being relinquished. This decline has come about due to improvements in water clarity leaving the fish increasingly vulnerable to predation. This then leads to fish congregating around structures like bridges, mooring and areas of bank margins and under trees. This leads to the majority of the channel being underexploited by fish as it provides poor fish habitat and as a consequence doesn’t meets its expected fish density due to its open cover free aspect. Recent fish surveys on the lower River Witham have highlighted how poor the available fish habitat is and there is a real risk of a decline in WFD status for fish. The only real areas of fish habitat on the lower Witham correspond with areas of trees and good marginal vegetation. The lack of available habitat and cover becomes a bottleneck for fish populations reducing survival of different year classes of coarse fish and is the limiting factor to fish density.

Whilst water quality improvements in clarity has had negative effects for fish populations due to an increase in predation pressure, the improvements to water quality will have had positive benefits for invertebrates, macrophytes and for recreational users.

1.2. The Water Framework Directive

The EU Water Framework Directive (WFD) provides an approach to investigate, plan and deliver a better water environment, based on biological, chemical and physical assessment indicators. The Environment Agency (EA) has assessed the ecological status (or health) of all water bodies in England and Wales based on fish, macrophytes (plants), diatoms (algae), invertebrates (insects), on chemical factors such as phosphate and dissolved oxygen levels, and on stream flow and channel morphology.

The WFD assessments have been used to assign every river water body to one of five ecological status classes: high, good, moderate, poor, or bad. A river in its pristine, or un- disturbed, natural condition would be classified as being High Ecological Status. The various elements of the WFD classification procedure are shown in Figure 1.2, and a failure in any one of these elements results in the failure of a water body to achieve the target classification of Good Ecological Status or Potential (GES or GEP). Importantly, the WFD requires that all water bodies achieve GES/GEP by 2015: where this is not possible, a programme of mitigation measures must be identified and implemented to ensure that GES or GEP can be achieved in the longer-term.

Figure 1.1: The Lower River Witham catchment

The Lower Witham is designated as an artificial water body under WFD. This is due to the use of the watercourse for navigation, flood protection and land drainage purposes. Its status is currently moderate and the target is to achieve good ecological potential. It’s currently failing for high levels of phosphates, low levels of dissolved oxygen, poor invertebrate, macrophyte and phytobenthos diversity, mitigation measures, and the heavily modified flow and morphological condition of river channels. (Figure 1.3).

As part of the process of deciding if good ecological potential is being achieved a number of criteria must be considered for the lower Witham, e.g. preserve and where possible enhance ecological value of marginal aquatic habitat, banks and riparian zone, and managing structures to enable fish passage. Unless these measures are deemed to be economically or technically infeasible they will be expected to be in place. A number of mitigation measures that are designed to restore the physical habitat component of the Lower Witham have been identified and include:

 Removal of obsolete structures.  Removal of hard bank reinforcement / revetment, or replacement with soft engineering solution.  Preserve and where possible restore aquatic habitat.  Increase in-channel morphological diversity.  Re-opening existing culverts and alteration of channel beds within culvert.  Flood bunds (earth banks) in place of floodwalls.  Set back embankments to increase flood storage.  Improve flood plain connectivity.  Structures or other mechanisms in place and managed to enable fish to access waters upstream and downstream of the impounding works;  Manage the risks of fish entrainment in intakes for hydropower turbines or water resource purposes (or pumping stations) where there is downstream migration.  Preserve and where possible enhance ecological value of marginal aquatic habitat, bank and riparian zones.  Operational and structural changes to locks, sluices, weirs, beach control etc.  Selective vegetation control regime, and appropriate vegetation control technique and timings. Overall Status / Potential

Chemical Status / Ecological Status / Potential Potential

Substances which Physico-chemical Biological elements Specific pollutants Hydromorphology present a significant (e.g nutrients, pH, (e.g. phytoplankton, (e.g. metals and their (e.g. depth, width, risk to the water dissolved oxygen). fish, invertebrates). compounds). flow, structure). environment.

Figure 1.2: Components of the WFD assessment

Figure 1.3: Map of WFD ecological status/potential

1.3. The Purpose of this Plan

As this is a heavily managed watercourse for flood conveyance and navigation the aims for this plan are to protect and enhance existing habitat whilst scoping opportunities for further works to the river corridor. While the focus of attention is on habitat improvement for the benefit of riverine wildlife, the plan is also intended as a basis for improving the river environment for the public (e.g. by improving fisheries, aesthetic quality and other amenity resources).

Acoustic fish surveys on the lower Witham have highlighted the lack of available habitat present. and Wwhere good levels of fish are recorded these correlate to structures such as bridge structures which provide overhead and structural cover, trees that provide shade, root structure and occasionally limbs that touch the water and marginal vegetation which has been allowed to develop. Part of this survey was linked in with acoustic bat surveying which provided evidence of a variety of bat species using the river corridor in particular where trees and margins were. A critical part of this report is to highlight these areas of good habitat and protect them from removal to retain a baseline habitat reservoir to build on improving wildlife populations from. As part of this plan a tree management strategy will be developed which will highlight the most important areas to preserve, maintain and plant. The preservation through appropriate management will ensure that the WFD current status does not deteriorate. APEM walkover surveys were carried out last year to identify key terrestrial areas to protect and enhance biodiversity on sections of the lower Witham.

These habitat retention and improvement works identified in the plan are essential in order to achieve the objectives of the WFD, by implementing mitigation measures such as those listed previously in Section 1.2. Some of the typical approaches to river corridor habitat improvement outlined in this document include:

 Retaining marginal trees that provide shade and cover in different flows  Introducing woody material;  Retaining marginal vegetation and encouraging diversity when managing weed cutting to create bays and scallops within the channel providing different flow patterns.  Creating refuge habitat;  Reconnecting rivers and floodplains;  Improving channel bed and bank vegetation;  Reducing localised erosion and sedimentation; and  Removing/altering impoundments to improve fish passage, flow continuity and sediment transfer.

The second main objective is to engage local partners to coordinate, agree, design and deliver river corridor habitat schemes throughout the catchment. There is a wide range of stakeholders and potential partnership organisations in the lower Witham catchment, including the EA, local authorities, IDB, charities, interest groups and landowners. During 2014, all of these stakeholders will be identified and consulted for their views on how this action plan can be extended, improved and delivered. Together, our broad vision for the future is that the lower Witham will:  Be cleaner and healthier;  Support more fish, birds and other wildlife;  Meet the needs of business;  Provide a more attractive place for people to enjoy through a variety of uses including angling and navigation.  Continue to provide drainage and manage flood risk;  Be sensitively managed by everyone whose activities affect it.

1.4. The Wider Context The habitat improvement schemes outlined in this plan form one element of a wider spectrum of activity and projects that are being delivered across the lower Witham catchment. Adopting a catchment-wide approach is necessary because schemes that focus solely on the river corridor cannot remedy all of the WFD failures. Table 1.1 provides a list of recent, current and future projects/activities that are highly relevant to this river habitat action plan.

Table 1.1: Other relevant projects/activities in the lower Witham catchment

Activity Location Organisation

Flood risk Opportunities Across the Environment Study catchment Agency, IDB

Lincoln Urban Plan Lincoln Witham Partnership

Witham Opportunities Across the Lincolnshire Wildlife Scheme catchment Trust; Environment Agency, IDB Fen creation Witham Peatlands Fens for the Future

Navigational Various Canal and Rivers improvements Trust

Black Sluice Catchment Black Sluice Environment Works Study Agency, Canal and Rivers Trust, IDB Wildlife Surveys Across the Lincolnshire Wildlife catchment Trust

Project Delivery Across the Lincolnshire Rivers catchment Trust, Environment Agency, Canal and Rivers Trust, IDB Eel Regulations Across the Environment compliance catchment Agency, IDB, Canal and Rivers Trust, Land owners Water Abstraction Across the Environment catchment Agency, Anglian Water

2. Present-day habitats

2.1. River character The lower River Witham runs through a predominantly agricultural catchment area, with several large urban areas including Lincoln and Boston as well as scattered small towns and villages. The gradient is flat with the river dropping onto clay bedrock and into a heavily modified trapezoidal channel, flanked by embankments that protect arable land and properties from flooding and a series of sluices for navigation and flood alleviation. As the gradient flattens out the river geomorphology changes and the sediment balance shifts from one of erosion and deposition to a sediment depositional balance. The sediment that has been transported down the river from various sources including natural geomorphological processes and from catchment farming practices would naturally settle out in flood conditions when the water level overtops the banks into the flood plain. The way the river is managed and controlled throughout the year prevents connectivity with the flood plain and controlling water levels in summer leads to sediment deposition on the river bed and around flow control structures like sluices. The extra nutrients in the sediment combined with holding levels through water control structures leads to the river acting as a still wate.r. This can promote excess blooms of algae and macrophytes creating the potential for the channel to choke up. Management and maintenance like weed cutting and de-silting is then needed to control this to aid flood management and navigation.

Downstream changes in river management represent both opportunities and constraints for river corridor habitat improvement projects. Therefore, for the purposes of this action plan, the river has been categorised into three zone reaches of the catchment (see below and Figure 2.1). These zones include up to the first structures on waterbodies that join the main Witham and that provide habitat and refuge areas for riverine wildlife on the Witham.  Zone 1: From Stamp End lock to Bardney lock. The water level on the main Witham is held at the same retained level all year. Formatted: Font: Bold  Formatted: Indent: Left: 1.25 cm, No bullets or  Zone 2: This section starts downstream of Bardney Lock following the main Witham numbering to the downstream confluence of the River Bain. Along the main Witham are various interconnecting drains and watercourses which are also included in this zone. For the purpose of this report we are including them as available Witham habitat up to the first structure. This includes a very short section of the North Delph up to a pump station at the bottom of the system which joins the old Witham below Fiskerton sluice. Joining the old Witham the Barlings Eau comes in behind Branston Island and Snakeholme Drain meets the old Witham before it joins the main Witham below Bardney Lock. The South Delph meets here and extends into Lincoln. For the basis of this report the upper limit of the South Delph has been classified as level with Stamp End above which will be covered in a potential Witham urban plan. The South Delph is joined by Branston Delph. The main Witham flows south where it’s then joined by the Nocton Delph, the entrance to the Metheringham Delph, Timberland Delph, and Billinghay Skirth. The water level for zone 2 is subject to winter and summer water level management. Formatted: Font: Bold  Formatted: Indent: Left: 1.25 cm, No bullets or  Zone 3: The lower reaches of the lower Witham flows south from the confluence of numbering the River Bain to Grand Sluice at Boston. This includes up to the first structure on the Kyme Eau. The water level for zone 3 is subject to winter and summer water level management

2.2. Catchment-scale habitat issues The character of existing river corridor habitats in the lower Witham catchment is to a large extent the product of past and present uses of the channel network and the surrounding landscape which it drains. Many of these uses create pressures which serve to hinder the natural processes and functions of the river system. Table 2.2 outlines the key pressures and associated negative impacts on the lower Witham river corridor, along with information about how habitat works can help to mitigate these impacts.

Table 2.2: Key pressures, impacts and mitigation measures in the lower Witham catchment. Pressure Cause Impacts Mitigation Water Level Varying water levels  Different water level heights ensure  Holding retained management set at summer and that marginal vegetation cannot levels year round winter levels to aid establish reducing cover for fish and would allow marginal navigation in invertebrates in both summer and vegetation to establish summer and winter flows. and provide cover. drainage in winter.  Reduction in levels increases water speed reducing juvenile fish survival and increasing washing out of fish and invertebrates to the sea.  Reduction in cover increases predation pressure. Impoundments Weirs, sluices, and  Increased risk of low flows with  Fish passage can be other obstructions associated impacts on water quality improved through have been placed in (eg, low dissolved oxygen) and removal/lowering of the river to control ecology. an obstruction or river levels for flood  Un-natural flow and sediment creation of a fish pass. defence protecting regimes which can alter existing  Removal or lowering against tidal surges, habitats. of impounding allowing monitoring  Prevention or hindrance to fish structures will also of flood levels, aid migration and ecological continuity. allow a more natural navigation, flow and sediment ensuring sufficient regime but it is water for irrigation accepted that removal and public water is not possible where supply. the structures have an essential function. Pressure Cause Impacts Mitigation Routine Routine  Removal of marginal and in-channel  More sensitive and maintenance maintenance of the vegetation reduces valuable food sustainable regimes bank side, marginal supply as well as cover and refuge management regimes and in-channel for fish, invertebrates and riverine can be developed by vegetation (largely mammals. It also removes spawning working closely with carried out for media for certain fish species. the respective channel navigation  Removal of bank-side trees and managers using the purposes). scrub reduces cover and food suite of environmental supply for fish and other fauna, options available such as bats. A lack of trees has Habitat enhancement been linked to elevated water works can be temperatures and reduced undertaken as part of dissolved oxygen levels which can these sensitive lead to death of fish and their eggs. management regimes.  Dredging to remove silt can reduce bed diversity and over deepen  Any works that involve channel. Many species of dredging should try to freshwater mussels use the concentrate in centre marginal areas for their lifecycles of channel where and can be removed by dredging. mussels are unlikely to Nutrient-rich dredged material (silt be found, any works and vegetation) is often left on the to margins should banks leading to a monoculture of have a banksman to nutrient-loving species (e.g. nettles return mussels etc and thistles which have poor back to the river. ecological value).

Altered Historic alterations  Removal and/or loss of natural  Numerous channel to the channel for features such as meander bends, enhancement options morphology industry and water low level sediment berms, leading are available to create conveyance to reduced diversity of substrate, the desired channel including creation flow and depth. This reduces morphology, from of mill streams, habitat value for flora and fauna. backwater refuge straightening,  Over-deepening and flood creation, bank widening, embankment disconnects the river lowering and river deepening and from its surrounding floodplain, floodplain construction of leading to high flow velocities reconnection. flood defences (e.g. during flood flows, with associated  Where high velocities walls and channel erosion and sedimentation. and undesirable embankments).  Over-widening and over-deepening erosion occur, reduces channel flow velocities measures to protect often leading to a shallower river banks and provide with high sedimentation rates and fish/wildlife refuge often excessive growth of in- can be implemented. channel vegetation.

Diffuse and Inputs of sediment,  Fine-grained sedimentation upon  In-channel works can point source nutrients and river gravels reduces habitat quality also be undertaken to pollution pesticides from for fish, plants and invertebrates reduce excessive fields, roads, and provides a pathway and sink for erosion and improve industry and urban adsorbed nutrients and pesticides. flows, thus minimising areas. Sources are  Excessive phosphate is a key issue sediment inputs. throughout upper in the river catchment that can lead  Sediment sinks / silt and lower Witham to excessive plant growth which in traps can also be catchment and turn can restrict flows, deplete created to encourage Pressure Cause Impacts Mitigation from fenland area oxygen and adversely affect fish, deposition in selected drains and pump plants and invertebrates. areas (e.g. marginal stations. berms). Invasive Non-native flora  Non-native flora can spread rapidly  Although invasive species and fauna, such as and out-compete the native species control is Himalayan balsam, vegetation. Their root systems can typically tackled on a Japanese cause significant damage to catchment scale and

knotweed, Azolla, structures and their rapid growth may form a major Pennywort, Mink, can choke rivers and leave the river project in itself, Signal crayfish, banks devoid of vegetation in the management of Chinese mitten winter (the latter increases the risk invasive species crabs, and DH of bank erosion and potential should be considered shrimp have been flooding). as part of any habitat introduced from  Non-native fauna in the Lower enhancement works overseas and are Witham system have potential for to avoid spread of the difficult to control ecological damage. The signal species. Azolla beetles effectively. crayfish, currently present on the have been trialled in River Bain, out-competes our native the past. white clawed crayfish (populations remain on the Upper Witham  Bio-security measures around Grantham) as well as should be undertaken carrying a fungal disease which kills when carrying out any the native species. works in-stream to

ensure accidental They also cause damage to spread is limited. riverbanks by deep burrowing and can reduce fish stocks by eating large amounts of fish eggs. The mink provides a threat to fish stocks where populations are already

suffering from other pressures and may also be a contributing factor to the decline of water voles in the catchment. Chinese mitten crabs have been found at Short ferry and are likely to be found throughout the lower Witham catchment. They burrow into banks causing sedimentation and can reduce fish stock through predation. DH shrimps have been found in several spots along the lower Witham and are thought to have been transferred through the Trent Witham Ancholme water transfer system. They out compete native invertebrate species.

Trent, Witham, Risk of spreading  DH shrimp spread through water  Ancholme invasive species transfer scheme, potential for other water transfer within these invasive species transference. for farmland catchments,  Potential for further transference if Pressure Cause Impacts Mitigation irrigation, entrainment of fish the Fens waterway link goes ahead industrial use and invertebrates linking the south forty foot to the and public and water quality of River Glen. water supply. receiving water.

Figure 2.1: Map of action plan zones

Figure 2.2: River engineering modifications showing obstructions and flood embankments

2.3. Reach-Specific Habitat Issues

Zone 1 (upper reach)

River Witham below Stamp end Over-deepened and embanked river channel disconnecting sediment transport within its natural floodplain

Limited marginal habitat which is heavily managed for flood defence and navigation. Limited shading from bank side trees which are heavily managed for flood defence and navigation which can encourage excessive algal and macrophyte growth.

Zone 2 (middle reach)

River Witham below Fiskerton Stone toe and subject to winter and summer water level management. This extreme range in water heights prevents marginal vegetation establishing which limits cover for fish populations reducing survival rates for juveniles and adults.

Over-deepened and embanked river Lack of channel channel disconnecting bank tree/scrub sediment transport vegetation within its natural floodplain

Zone 3 (lower reach)

Stone toe and subject to winter and summer Barrier to fish movement; flow and sediment water level management upstream discontinuity restricting marginal vegetation, limiting cover for fish populations reducing survival rates.

Over-deepened and embanked river channel upstream of Grand Sluice disconnecting sediment transport within its natural Lower River Witham at Grand Sluice floodplain

3. Dealing with Habitat Issues

As stated earlier in the report the aim of this plan is to preserve the existing small patches of habitat which are essential to maintain fish population and provide diverse habitat for a variety of wildlife species whilst identifying opportunities for potential habitat improvements. In simple terms the river is lacking in a diversity of habitats and flow types with a resulting lower level of fish populations and other riverine wildlife supported. The aim is to reverse this trend and create a wider variety of river habitats which can then support healthier populations of flora and fauna.

The key aspects that need to be considered when trying to deal with habitat issues are detailed below however full details of the systematic process undertaken in the planning and implementation of river corridor habitat works is provided in Appendix A.

3.1. Idealised river habitats

A typical example of good river habitat comprises some of the following physical features:

 A natural functioning channel with connection to the floodplain, natural sediment transport regime, and good diversity in flow, substrate and depth;  A sinuous profile with physical features such as low level sediment berms, backwaters, and eroded banks;  A diverse mix of in channel, marginal and bank-side vegetation providing food, cover and shelter for fish, invertebrates and mammals; and  Clean bed substrate and/or channel weed to provide spawning media for fish and also habitat for aquatic invertebrates.

Barlings Eau:- Example of idealised river habitat for fish in a lowland section of embanked river- note the two stage channel with sediment berms supporting healthy marginal vegetation cover and tree cover touching and hanging over the water providing shade and habitat. To ensure retention of good habitat like the overhanging trees that are present, regular sensitive management like coppicing or pollarding on a rotation would ensure that there is always habitat available rather than reactive management when trees are deemed to be an issue to conveyance and are heavily managed.

3.2. Setting Realistic Targets It is not necessarily feasible or desirable to restore the river to a past condition when there was little modification or pressure on the watercourse. Where pressures remain present on the river a more realistic and sustainable target would be to replicate a section of river where present-day habitats are considered to be in good condition. These sections of relatively good habitat, where more natural processes have both developed and sustained the key attributes of a healthy river corridor (e.g. backwaters, low level sediment berms, woody material, retained water levels encouraging good marginal vegetation cover) can be used to inform improvement schemes on other sections of the river.

The data sheets provided below illustrate the nature of relatively good existing river corridor habitat within zones 1, 2, and 3 (see Section 2.1 and Figure 2.2) of the Lower Witham catchment. The sheets demonstrate the key physical features and processes that provide habitat to support and sustain healthy populations of fish, flora and invertebrates as well as the added benefits of an actively functioning river (e.g. improved recreational value). The data sheets also list some typical target species that provide key indications of a healthy river corridor. These sheets can be used as a guideline when conducting improvement works in the different zones of the river catchment.

Lower Witham Zone 1 Retained levels: Target Habitats and Species Data Sheet Habitats  Marginal and in-channel vegetation cover Lower Witham below Stamp End which is allowed to encroach into the river. Sustainable weed cutting using

environmental options to create sinuous marginal bays providing a mosaic of habitats.  Bank-side and in-channel large woody material;  Riparian tree and shrub cover particularly where branches hang into the water providing refuge for fish in different flows and from predators. The tree cover provides cover and feeding stations for bats  Downstream fish passage through Stamp End lock into lower Witham in summer when navigation in operation.  Open access for fish into Zone 2 & 3 through a Larinier and eel pass on Fiskerton sluice.  Online flow refuge provided by entrance to Branston Delph. There is potential to open up access into Branston Delph which is currently sealed where there is good upstream habitat. This would involve anti seepage works or a change in land use around the Delph.  Mown grass banks maintained by EA Operations staff increases mosaic of habitats available encouraging variety of species of small mammals and owls.  Unconnected wetland habitats increase diversity for mammals and birds at sites like Fiskerton Fen.  Moorings, boats and bridges provide structural cover for fish.

Species  Grebes, Kingfisher: an indicator of healthy fish stocks and good physical habitat quality);  Coarse fish (e.g. Common Bream, Silver Bream, Roach, Carp, Perch, Pike, Spined loach*).  Migratory fish, eel and lamprey.  Otter*, Bats (e.g. Daubenton’s, Noctule, Common and Soprano pipistrelle. )  Invertebrates (e.g. Dragonflies, Caddis, Compressed River Mussel*, Swollen River Mussel, Pea Mussels, Orb Mussels, including the Witham Orb Mussel** and the False Orb Mussel**)  Plants, including Common Reed, Reed Sweet Grass and Fringed water lilies provide cover for invertebrates, wildfowl and fish.

(* Biodiversity 2020 designated species)(**Red data species)

Lower Witham Zone 2 Target Habitats and Species Data Sheet

Habitats  Marginal and in-channel vegetation cover on main river in particular in areas behind where stone toe has been eroded and marginal vegetation has been able to colonise as not subject

to variation in water levels.  Backwaters/bays for still-water habitat and open access high-flow refuge available on the Nocton Delph.  Riparian tree and shrub cover Lower Witham around particularly where branches hang Billinghay into the water providing refuge for fish in different flows and from predators. The tree cover provides cover and feeding stations for bats.  Wetland wildfowl refuge provided at Branston Island and adjacent to Short Ferry pump station.  Moorings, boats and bridges provide structural cover for fish  Mown grass banks maintained by EA Operations staff increases mosaic of habitats available encouraging variety of species of small mammals and owls.

Species  Grebes, Kingfisher: an indicator of healthy fish stocks and good physical habitat quality;  Coarse fish e.g.( Common Bream, Silver Bream, Roach, Carp, Perch, Pike, Spined loach*)  Migratory fish e.g. fish, eel and lamprey;  Water vole*, otter**, Bats (e.g. Daubenton’s, Noctule, Common and Soprano pipistrelle.)  Invertebrates (e.g. Dragonflies, Caddis, Compressed River Mussel*, Swollen River Mussel, Pea Mussels, Orb Mussels, including the Witham Orb Mussel** and the False Orb Mussel**)  Plants, including Common reed, Reed sweet grass and Fringed water lilies provide cover for invertebrates, wildfowl and fish.

(* Biodiversity 2020 designated species) )(**Red data species)

Lower Witham Zone 3 Target Habitats and Species Data Sheet

Habitats  Marginal and in-channel vegetation cover on main river, in particular in areas behind where stone toe has been eroded and marginal vegetation has been able to colonise as not subject

to variation in water levels.  Backwaters/bays for still-water habitat and high-flow refuge available on Kyme Eau entrance.  Riparian tree and shrub cover particularly where branches hang into the water providing refuge for fish in different flows and from predators. The tree cover provides cover and feeding stations for bats.  Moorings, boats and bridges provide structural cover for fish  Mown grass banks maintained by EA Operations staff increases mosaic of Lower habitats available encouraging variety of Witham below species of small mammals and owls. Kyme Eau

Species  Kingfisher: an indicator of healthy fish stocks and good physical habitat quality;  Coarse fish (e.g. Common Bream, Silver Bream, Roach, Carp, Perch, Pike, Spined loach*)  Migratory fish e.g. fish including smelt, eel and lamprey;  Water vole*, otter*, Bats (e.g. Daubenton’s, Noctule, Common and Soprano pipistrelle)  Invertebrates (e.g. Dragonflies, Caddis, Compressed River Mussel*, Swollen River Mussel, Pea Mussels, Orb Mussels, including the Witham Orb Mussel** and the False Orb Mussel**)  Plants, including Common reed, Reed Sweet Grass and Fringed water lilies.

(* Biodiversity 2020 designated species) )(**Red data species)

3.3. Choosing Appropriate Techniques Due to the intensive need for management that this system requires there are limited options for improvements. These options are limited by a need to provide flood defence, navigation and abstraction and selection may also boil down to other logistical factors such as local availability of materials or landowner preferences. However as the habitat is currently so poor any minor changes have the potential for large biodiversity impacts.

The techniques that are potentially most suitable for habitat improvement works in the lower Witham catchment are listed in Table 3.1. It is important to note that often a combination of techniques will be required to provide a successful and sustainable solution. For example, opening up the delphs may require the use of a deflector upstream of the entrance to the delph to slow river flow providing slack water to allow easy access for fry to reach the refuge in high flows. It may also require significant engineering works or a change in land use as embankments on delphs are set lower than the Witham. 22

Table 3.1: Habitat improvement techniques

Technique Purpose/Impacts

Retain single  Allow colonisation of marginal vegetation by retaining single water level all year round. water level all This could provide soft bank protection as opposed to stone hard bank protection. year round.  Enables fish to access valuable spawning areas of marginal vegetation.

Creation of a  Reduce need for maintenance by creating a low flow and higher flow channel increasing two stage water retention within the channel and reducing sediment deposition in channel. This channel would improve biodiversity and aesthetics whilst reducing maintenance and allowing navigation. Flow deflectors  Provide shelter around the entrance to the delphs allowing fish to access refuge in high flows. Tree/shrub  Provide food, cover, refuge and shade for fish, invertebrates, birds and other mammals. planting and  Create shade to reduce excessive in-channel weed growth and a stable environment in maintenance terms of temperature and oxygen levels.  Use species of trees like Hawthorns and Blackthorn which are slow growing, needing minimal maintenance and having smaller root balls so less impact on embanked flood defences.  Creation of a tree management strategy to highlight areas of good habitat and ensure appropriate traditional maintenance to preserve the longevity of the trees e.g. coppicing, pollarding, crown lifting etc dependent on species.

Woody  Create physical habitat for many species of plants, invertebrates and fish (e.g. refuge for material fish.) introduction Remove/alter  Improve fish passage and ecological connectivity. impoundments Reconnect  Provide refuge and migration pathways for aquatic fauna during high flow events, rivers and currently South Delph acts as a refuge for fish in higher flows on the River Witham and floodplains potential for opening further delph access. including  Reconnect to floodplain habitats such as delphs. backwaters  Creation of wetland habitat in washlands. and washlands  Create backwater online fish refuges.

4 Action Plan

Table 4.1 presents the ongoing and potential planned actions within the lower River Witham catchment that are aimed at improving the river corridor habitats and meeting WFD targets. The proposed action plans are specifically broken down for the three river zones, in addition to those that are relevant across the whole catchment area.

Table 4.1: River corridor habitat action plan Location Driver Action Lead Type

Catchment-wide

Catchment Partnership working Engage with the other relevant All Partners Short Term initiatives/projects as listed in Action Table 1.1 Catchment Operational Review current river management All Partners Short Term management plans and requirements. Action Catchment Operational Develop Tree Management All Partners Short Term management Strategy Action Catchment Operational Develop single water level plan to All Partners Long Term management encourage marginal vegetation. Plan Catchment Operational Develop and deliver Witham eel All Partners Short Term management and fish pass plan. Action Catchment Knowledge acquisition Establish woody material All ShortMedi demonstration/monitoring sites. Partners um Term Action Catchment Operational Install spawning media under all CRT / EA Medium management CRT moorings. Term action Catchment Awareness raising Publish habitat improvement case EA MediumLo studies and promote value of ng Term works when carried out. Action Catchment Operational Creation of a two stage channel to EA Long Term management improve habitat whilst reducing Plan maintenance and dredging. Creation of wetlands and fens. Catchment Operational Develop and encourage sustainable EA Long Term management farming in upper and lower reaches Plan of catchment with catchment sensitive farming.

Zone 1 (Upper reach) In terms of three zones this has the best current habitat.

Stamp End to Lack of suitable in-stream, Maintain existing tree cover and EA Short Term Bardney riparian vegetation and riparian vegetation providing a Plan cover for fish life cycle variety of terrestrial and aquatic habitatt.. Areas where in-stream aquatic vegetation present should be retained as it provides valuable invertebrate and fish cover and a medium for fish spawning. APEM report on Lower Witham highlights these areas for protection.

Stamp End to Lack of suitable instream, Hinge bankside trees and secure EA / CRT Short term Bardney riparian vegetation and in margins to create overhead started cover for fish life cycle cover and provide spawning 1/2/16 media. Stamp End to Lack of suitable instream, Use of mesh cages filled with EA Short term Bardney riparian vegetation and brushwood and barley straw to started cover for fish life cycle provide overhead cover and 2015 spawning media. Stamp End Lock Barrier to fish and eel Install fish and eel pass solution. EA Long Term movement. Plan Cherry Willingham Straightened channel, Creation of online refuge, setting EA Witham Long Term Fen creation limited off line refuge for flood banks back, provides a Opportunities Plan fry in higher water levels. online fish refuge and increases Mapping habitat diversity. Washingborough Straightened channel, Creation of wash lands, setting EA Witham Long Term Fens creation limited off line refuge for flood banks back, provides a Opportunities Plan fry in higher water levels. online fish refuge and increases Mapping habitat diversity. Fiskerton eel and fish Current fish and eel Maintain fish passage on EA Short Term pass passage through Larinier structure. Plan and bristle boards.

Zone 2 (Middle reach) This zone has slightly less current habitat but a large scope for improvements.

River Witham d/s Lack of suitable riparian Maintain existing tree cover and EA Short Term Bardney vegetation and cover for riparian vegetation. Amount of Plan fish life cycle, invertebrates habitat impacts on fish / ecology and mammals. populations further downstream in zone 3

Washlands Providing good wetland Scope for further improvement EA / Long Term habitat for bird, plant and works / scrapes and land Landowner, Plan fish populations. management and for use as a Witham template. Opportunities Mapping Billinghay Skirth, Lack of suitable riparian Maintain existing tree cover and EA Short Term Snakeholme drain, vegetation and cover for riparian vegetation. Protect / Plan River Bain, North, fish life cycle, invertebrates enhance through widening South, Branston, and mammals. entrance to create online refuge Nocton and to Delphs, Skirth and drain as Timberland Delphs Fish and eel passage cover from high flows in Witham.

Open access through control structures where possible to allow access to spawning and juvenile coarse fish habitat in a range of flows.

Deepen with selective dredging at bottom of delphs to increase fish habitat and access to spawning habitat upstream.

Branston, Sedimentation and Develop community limestone LRT, EA, Short Washingborough, providing good wetland becks projects to slow the flow Landowners Term, Nocton, Dunston, habitat for bird, plant and into Delphs reducing works Metheringham fish populations. sedimentation and improving started fish populations 2013 25

Tattershall Bridge Lack of suitable riparian Potential for fish refuge EA / CRT Short Term vegetation and cover for Plan fish life cycle, invertebrates and mammals Barlings Eau - Straightened, over-widened Create wash land with flood EA Witham Long Term Langworth, Barlings impounded channel. banks set back. Retain bank side Opportunities Plan Hall, and Lower trees and marginal habitat cover. Mapping Barlings Eau and Provide fish passage either by Short Ferry Flood removing barrier or installing fish storage / eel pass. Branston island Wide low level grass berm Scope to add an online fish EA Short Term wash lands outfall providing some habitat. refuge by digging out an area to Plan provide cover from winter flows. All of Zone 2 Barriers to fish and eel Maintain fish passage through All Partners Short Term movement. control structures where Plan available and improve passage beyond barriers.

Zone 3 (Lower reach) This is the zone with the most limited habitat so critical to retain what habitat is present, and closer to the tidal influence.

Lower Witham Straightened, over- Maintain existing tree cover and EA Short Term widened, embanked riparian vegetation. Plan channel. Lack of suitable riparian vegetation and cover for fish life cycle. Lower Witham Limited marginal and online Lowering the stone toe in EA Short Term where appropriate fish refuge in variety of selected places and excavation Plan trial at Kyme Eau flows for fish and back into earth where invertebrates. appropriate to create online refuge for fish and invertebrates in high and low flows. Woody material to be added behind to protect banks and provide refuge. Kyme Eau Barrier to fish movement. Remove barrier or install EA Long Term fish/eel passes. Plan

Chapel Hill Limited marginal and online Create online flow fish refuge by EA Delivered fish refuge in variety of excavating flood bank. flows for fish and invertebrates.

Antons Gowt Straightened, over- Provide refuge behind moorings EA Long Term widened, embanked and jetties. Plan channel. Grand Sluice Barrier to salmonid, eels, Ensure fish migration by EA Medium and smelt migration. installation of fish pass. Term Plan All of Zone 3 Barriers to fish and eel Maintain fish passage through All Partners Short Term movement. control structures where Plan available and improve passage beyond barriers.

APPENDIX A: Approach to river corridor habitat works

A systematic approach is required for river enhancement works from project inception through to delivery and monitoring. This ensures that not only is the work targeted to where it is most needed but also allows us to monitor its effectiveness and learn lessons for future works. The typical approach taken is illustrated in Figure A1 and each stage is described in more detail below.

Desk study and site walk-over: Undertake an initial desk study and site walk-over to understand site specific and wider catchment considerations. Data reviewed typically includes the following:

 Existing data that has informed the WFD classification; and  Long profile survey data of the river to characterise channel bed gradients, illustrate existing impoundments and assess their upstream ponding effects.

During this early stage one would also consult with landowners and other relevant stakeholders to gauge their requirements and ideas.

Desk Study and Site Walkover

Identify Limiting Factors

Identify Locations for Enhancement

Consider Appropriate Techniques

Prepare Strategy for Pre/Post Monitoring and Management

Monitor and Review

Figure A1: The 6 key steps involved in the approach to river habitat enhancement works

Identify limiting factors: It is important to identify the limiting elements of the river reach and the wider river system, whether this be a lack of water for local landowner needs or a missing stage in the life cycle of a target species (e.g. lack of deep water for adult fish, lack

of aquatic vegetation for fish spawning, lack of refuge for fish/other aquatic fauna in times of high flow.

Identify locations for enhancement: By identifying the limiting factors along both individual reaches and the longer river section, it is then possible to target suitable locations for enhancement works. For example, if aquatic vegetation is not provided on a short reach but are known to be present in a connected upstream reach, the requirements of the particular species (in this case fish) for spawning medium is still likely to be met. By contrast, if lack of refuge for juvenile fish in high flow periods were lacking throughout the system then it would be more beneficial to put time and resources into sustainable creation of this habitat for the benefit of the short and connected reaches. All elements can be tackled but realistically works should be targeted to where most gain under the WFD and other targets can be achieved within a given budget. Other factors influencing locations may include ease of site access and land ownership. Much of the recent habitat work has been targeted on sections of the lower River Witham which are currently classified under the WFD as being in moderate to poor ecological status.

Choose appropriate techniques: Depending on the situation, there are numerous techniques that can be employed. Best practice guidance should be followed in terms of selection and siting of measures so that the solution is effective in the short and long-term. Selection may also come down to other considerations such as availability of local materials or landowner preferences.

The main techniques that were considered appropriate for habitat improvement works on the lower Witham are outlined in Table 3.1. It is important to note that often a combination of techniques will be required to ensure sustainable habitat improvement (e.g. creation of online fish refuges may involve siting a flow deflector above to aid fry to take refuge in higher flows).

Prepare strategy for pre/post monitoring and management: Successful restoration schemes include a sound programme of monitoring and management. As each river reacts differently to the outlined techniques, only monitoring will allow us to fully assess which techniques and methods are being successful, or otherwise. Low energy, low gradient rivers such as the lower Witham will also take time to respond and recover (typically 5 years or more dependent on the flow and sediment regime experienced during the years following the works). Although the aim is to create largely self-sustaining habitats, an element of management will also be needed.

Monitoring: Typical approaches to pre/post monitoring include:

 Fixed point photography: a simple and effective means of recording physical changes/impacts;  Biological surveys: fish, invertebrate and sediment surveys can be employed to quantify biological impacts;  Water level recording: important to assess the impact of structural (e.g. hatch) removal or redesign, or to assist in the design of a fish pass; 28

 Cross-sectional surveys and flow measurements: may be cost and resource prohibitive on smaller scale schemes but can inform selection and design of techniques as well as providing an evidence base for the results of the works;  Expert advice and audit processes: external bodies such as the River Restoration Centre, Wild Trout Trust and Rivers Trust can be contacted to assist in the design, delivery and monitoring of habitat schemes. Given the dynamic nature of rivers, sharing of best practice and lessons learnt is the best way to improve and adapt techniques.

Management: Ideally, channel works are designed to not only be easily adaptable but also the habitats created should be self-sustaining in order that management and maintenance requirements are minimal. An element of management is, however, vital to the long-term success of schemes and a commitment to this is needed. Management of the works may be undertaken by external organisations but the involvement of landowners and other interested parties, such as fishing clubs, is often the best arrangement. Management regimes and responsibilities need to be agreed at an early stage of the project.

Scheme design and implementation: scheme design needs to be based on a sound understanding of the system and the needs of its users. Other requirements during the design and implementation stage are legal obligations, such as planning permissions, flood risk assessments, consents and licensing (e.g. impoundment licenses, flood defence consents, waste licenses or protected areas/species licensing) and health and safety requirements under the Construction (Design and Management) Regulations, 2007 (CDM). It is also important to use local materials where possible to reduce scheme and environmental costs.