Case study:Houghton 'trout stream' enhancements

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Location: 52° 19' 30.02" N, 0° 6' 26.70" W

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Project overview

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Status	Complete
Project web site
Themes	Fisheries, Hydromorphology
Country	England
Main contact forename	Rob
Main contact surname	Clapham
Main contact user ID
Contact organisation	Environment Agency
Contact organisation web site	http://www.gov.uk/government/organisations/environment-agency
Partner organisations
Parent multi-site project
This is a parent project encompassing the following projects	No

Installation of a mid-channel 'v' deflector to create and maintain clean gravels

Project summary

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The Environment Agency worked with local stakeholders to improve habitat quality on a side-channel of the Great Ouse.

Like many of our rivers, the Houghton 'trout' stream, has been significantly modified over many years. These modifications include impoundment, channelization and tree clearance. These pressures have reduced the resilience of the channel to wider catchment scale pressures from water quality and sediment.

As a result of these modifications, there is insufficient flow and energy within the channel at many times of the year to move and redistribute sediment within the channel. This has meant that this 'naturally' gravelly river has an overlying layer of fine sediment. This significantly reduces the likelihood of successful spawning by species such as chub, dace and barbel, the latter of which has not been seen on the river for over a decade.

Such habitats are particularly important to retain on this side channel, as the main river is navigable, heavily impounded, and cannot provide the diversity of habitats found on this channel, all of which are vital to many species at different points in their life cycle. Furthermore, due to navigation on the main channel, options to enhance or restore it are limited.

The Environment Agency surveyed the side channel and put together a series of enhancement options to address the deterioration, which were then shared and discussed with the local Angling club and landowners. These included: Improving flow over an upstream weir, tree planting, retaining woody material, fencing, gravel jetting, and installing deflectors to keep areas of spawning gravels free from silt and excessive vegetation growth. Both landowners and Angling Club were keen to see these improvements made and offered both their time and money to see them implemented.

Partnership was vital to success of the project. Very little money was spent on these enhancements with most contributions coming from volunteer time. The angling club have helped with planting of trees (willow whips sourced from local trees), gravel jetting (using agency equipment), and will share the cost of installing fencing with the local landowners Smith & Smith. The Agencies Fisheries and biodiversity team cleared vegetation blocking an upstream weir and installed flow deflectors, again using wood sourced from locally fallen tree that identified for removal as it was blocking a nearby drainage channel.

While enhancements such as tree planting will take many years until benefits from increased cover, shelter shading, and supply of woody material to the channel are realized. Already, the benefits of the gravel jetting and flow deflectors can be seen. Following the work, the areas of clean gravels have remained, while other areas in the channel (not yet enhanced) have become covered with sediment and clogged with reed growth.

For the first time in many years, large numbers of fish have been seen congregating around the deflectors in preparation to spawn, including many large chub. Furthermore, we have also seen River Lamprey (a formerly declining species) making use of the clean gravels for spawning.

This project demonstrates that correctly targeted low-cost measures, undertaken in partnership with committed stakeholders, can make significant improvement to river channel habitat and fisheries value.

Monitoring surveys and results

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Pre-enhancement fish surveys have been undertaken

The Environment Agency will continue to monitor this site through electric fishing surveys, and will continue to support the Angling club in making further enhancements.

Lessons learnt

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Wood for construction of deflectors was sourced locally and work was undertaken by hand. Therefore the size of deflectors were limited to what could be manoeuvred by hand. Despite their size, careful consideration of the prevailing flow and sediment conditions meant they could be placed to achieve optimum benefit.

Image gallery

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File:Lamprey Spawing.mov

Local angling club planting trees on banktop

Example of side deflector

Chub preparing to spawn around 'v' deflector

Finished deflector in May 2014

Catchment and subcatchment Select a catchment/subcatchment Edit the catchment and subcatchment details (affects all case studies in this subcatchment) Catchment River basin district Anglian River basin Upper and Bedford Ouse Subcatchment River name Ouse (Roxton to Earith) Area category 1000 - 10000 km² Area (km2) Maximum altitude category Less than 100 m Maximum altitude (m) 6565 m <br />0.065 km <br />6,500 cm <br /> Dominant geology Calcareous Ecoregion Great Britain Dominant land cover Arable and Horticulture Waterbody ID GB105033047921 Other case studies in this subcatchment: Houghton 'trout stream' enhancements Site Edit site Name WFD water body codes WFD (national) typology WFD water body name Pre-project morphology Reference morphology Desired post project morphology Heavily modified water body National/international site designation Local/regional site designations Protected species present Invasive species present Species of interest Dominant hydrology Dominant substrate River corridor land use Average bankfull channel width category Average bankfull channel width (m) Average bankfull channel depth category Average bankfull channel depth (m) Mean discharge category Mean annual discharge (m3/s) Average channel gradient category Average channel gradient Average unit stream power (W/m2) Project background Edit project background Reach length directly affected (m) Project started Works started Works completed Project completed Total cost category Total cost (k€) Benefit to cost ratio Funding sources Cost for project phases Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname Investigation and design Stakeholder engagement and communication Works and works supervision Post-project management and maintenance Monitoring Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Land drainage Hydromorphology Quantity & dynamics of flow Biology Physico-chemical Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications Creation of wooden deflectors, Cleaning of spawning gravels Floodplain / River corridor Fencing, Tree planting Planform / Channel pattern Other Non-structural measures Management interventions Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Fish Yes Yes No No No Physico-chemical quality elements Edit Physico-chemical quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Any other monitoring, e.g. social, economic Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Additional links and references Edit links and references Link Description Supplementary Information Edit Supplementary Information