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Summer river improvements

Posted: Wednesday 7th September 2016 by Living Rivers

River restoration, River StortRiver restoration, River Stort

Living Rivers Officer, David Johnson, tells us what he has been up to over the summer and how you can get involved.

Improving our local watercourses using wood

Installing woody material in watercourses is becoming an increasingly used method for restoring and enhancing our rivers. Using a variety of techniques from installing log deflectors and brash berms , to felling and pinning whole trees to the river bed, “natural” woody features are a simple and cost effective method for introducing a wide range of ecological habitat improvements to our chalk rivers.

This summer I have spent time on the River Lea assisting volunteer Living Rivers Champion, Patrick McNeill, Mark Carter and the Wheathampstead Open Space Volunteers to implement some of these techniques as part of their plan to restore the river through East Lane Carpark. The river on this stretch had a number of issues - being confined to a straight channel, a homogeneous flow regime and a lack of in-channel habitat features.

By installing a series of log flow deflectors and brash berms, from materials sourced on site, a much more heterogeneous flow regime is now present; this has the benefit of creating localised scour and deposition of sediments leading to a diverse habitat mosaic of clean gravel and cobbles in areas of fast flow, whilst silt and fine particles are being deposited in slower marginal areas which will eventually build up and become vegetated bars.

The improvements have already been utilised by the fish population with chub feeding on drifting invertebrates and barbel feeding in the clean gravel. Large shoals of minnow are also sheltering behind the deflectors and in-between the tangled branches that make up the brash berms. Using woody material also provides habitat and food for a variety of invertebrate species on which the fish population predates. River surveys and monitoring of the invertebrate populations within this stretch of river will continue to provide the data needed to measure the success of the project and continue to develop best practice as groups within the Lea Catchment begin planning and developing future projects.

Cost effective and easy to deliver, I am eager to see other groups throughout the Lea Catchment coming up with further project ideas. To facilitate this, I partnered with a local landowner, the Environment Agency, Affinity Water and the Wild Trout Trust on the River Stort to deliver two habitat creation workshops, teaching local river groups the information and techniques needed to deliver a successful project using woody material. Through working in partnership, as well as imparting knowledge of river restoration, the workshops also acted as a platform for wider river education with an introduction to Riverfly monitoring from myself and a demonstration of water saving devices by Affinity Water. The workshops also helped deliver part of the river restoration plan for the site, bringing it closer to completion.

The restoration of this stretch of the River Stort will require several more sessions to complete and I am looking to deliver these through the autumn (weather and funding permitted!) If you are interested in learning valuable river restoration skills and would like to do your bit to restore one of Hertfordshire’s rivers why not come along and help?

Catchment Partnership Meetings

This summer saw the Upper Lea, Middle Lea and Stort Catchment Partnership meetings take place. There is a lot of exciting work going on in the Upper Lea with the Batford Springs Volunteers continuing to develop ambitious plans to enhance the Batford Springs Local Nature Reserve and our own Living Rivers Champion Patrick McNeill (now known around town as the River Man) continuing his hard work to raise the profile of the River Lea through Wheathampstead.

At the Middle Lea meeting Feargal Sharkey, Archivist of Amwell Magna Fishery, delivered a thoroughly entertaining account of the 185 year history of the oldest angling club in Britain. You can see this for yourself at Hertfordshire Natural History Society’s Autumn Meeting and AGM in October where Feargal has agreed to be one of the speakers.

In the Stort, Thames Water reported on the work they have been doing to reduce Metaldehyde (slug killer) pollution through working with agricultural landowners, while Affinity Water have begun a project to engage people who are using Metaldehyde on a smaller scale, such as allotment tenants, to try alternative solutions.

The next big event for the Lea Catchment Partnership is the first ever River Lea Catchment Conference which will be held October 19th 7-10pm at Bayfordbury. This will be an excellent way to find out how the River Lea Catchment Partnership has been working to restore, conserve and enhance the River Lea and its tributaries for people and wildlife including an evening presentations by local experts, knowledge sharing, networking and looking to our catchment’s future. Spaces are limited and booking is essential.

Click here to find out more and book your place.


Back in May I , along with eleven Riverfly monitors from across the county, attended a Riverfly identification course at the University of Hertfordshire’s Bayfordbury Science Learning Centre. The course, delivered by Dr Ronni Edmonds Brown (UoH) and Patrycja Meadows (EA), introduced monitors to family level identification of mayflies, stoneflies and caddisflies they can expect to find in Hertfordshire.

In June Sir Oliver Heald MP for North East Hertfordshire, visited our Tewinbury Reserve on the River Mimram. A long term supporter of our Chalk Streams it was a pleasure to provide Sir Oliver with a demonstration of Riverfly monitoring.

I’ve also spent a couple of days throughout the summer in the Lower Lea catchment with partners from Lea Valley Regional Park, the Environment Agency and Natural England, helping the Environment Agency with dragon and damselfly exuvia surveys on the Cornmill Stream SSSI. The Cornmill Stream is designated a SSSI for the number of dragon and damselfly species it supports, with eighteen species recorded at designation. The survey data will help inform the Environment Agency on restoration options for the river, which has become sluggish and heavily silted.

For more information about the Living Rivers Project, river restoration workshops or to book your place at the River Lea Catchment Conference contact David Johnson, Hertfordshire Living Rivers Officer.

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