Latest Ouse Washes Middle Level Barrier Bank works newsletter

November 2019

The purpose of this Environment Agency project is to maintain the protection from flood risk for homes and businesses along the Ouse Washes.

What are the Ouse Washes?

The Ouse Washes is defined, under current legislation, as a ‘large raised reservoir’ more commonly known as Ouse Washes Flood Storage Reservoir. It is approximately 33km (22 miles) long and 1.7km (0.5 mile) wide providing about 2,000 hectares (5,000 acres) of land between the banks and it’s in Cambridgeshire. The Dutch Engineer ‘Sir Cornelius Vermuyden’ originally constructed it in 1653 for the purpose of draining the fens. It is designed to store floodwater that would otherwise cause overtopping of riverbanks. 

Over time the Washes has evolved into an important area for a variety of species and subsequently received local, national and international conservation status. It is also important from an agricultural aspect and is heavily grazed during the summer. This grazing serves a dual purpose, it facilitates the management of the Washes by controlling vegetation and maintaining the effective transfer of floodwater; it also acts as an effective technique to manage the grassland habitats of the Washes, providing best conditions for the vast array of bird species visiting the area.

diagram of the Ouse Washes
Aerial view of the Ouse Washes flooded

What work is required to maintain the Ouse Washes?

A qualified civil engineer completed an inspection in 2013 and recommended a number of Measures in the Interests of Safety under Section 10 (6) of the Act. These resulted in a project to raise the Middle Level Barrier Bank to address changes to the bank crest level caused by settlement.

The Middle Level Barrier Bank is lower where the Welney Wash road crosses into the Ouse Washes Flood Storage Reservoir. This low spot reduces the safety and stability of the bank and increases the flood risk to the communities. Historically the Environment Agency have created a temporary flood barrier across the Welney Wash road using large sand bags. Installing large sand bags is costly in terms of labour and waste, as the sand bags cannot be reused. 

The existing bank protects surrounding areas from flood water stored in the reservoir. A recent assessment of the bank height shows that flood water could overtop the bank at isolated locations in the equivalent of a 1% probability event.

Overtopping could lead to erosion and subsequent collapse of the bank. Under the Reservoirs Act 1975 the Middle Level Barrier Bank needs to be safe for a 0.1% probability event. Where communities are immediately adjacent to the bank, the Middle Level Barrier Bank needs to be safe for a 0.01% probability event.

aerial view of the Ouse Washe and Welney Wash road flooded
Aerial view of the Ouse Washes and the Welney Wash road flooded

What work is taking place?

The Environment Agency are raising the Middle Level Barrier Bank between Earith and Welmore Lake Sluice. Other associated works include building barrier works at Welney, a new wall at Welches Dam Pumping Station, extending a retaining wall at Sutton Gault, and decommissioning the Black Sluice culvert (near Earith).

This work is taking place over 4 summers (2017, 2018, 2019 and 2020). Due to the overwintering and breeding bird population found on the Washes, there is a narrow timeframe to do any work on the banks, from mid-July to end of October each year.

You can find out about the latest progress of the project through the link below:

Eels in the Classroom

We are pleased to announce that Cambridgeshire ACRE has received Anglian Water’s Flourishing Environment Fund grant to deliver a project that offers Primary School children a hands-on experience of rearing endangered eels in their classrooms in order to create a long-term legacy of eel conservation in the region.

Eel growing in school. Image from Bristol and Avon Rivers Trust:

European eels once thrived in the UK’s rivers, but their numbers have declined by over
95% since the 1980s and the species has been classified as ‘Critically Endangered’ by
the IUCN since 2008. Constructed weirs, tidal gates and dams all act as barriers to
migration, while pollution, climate change, overfishing and habitat loss all have a
negative impact on eel survival. Specifically, in the River Ouse the number of elvers
(young eels) trapped through Environment Agency (EA) monitoring has declined every
year since 2013 (2018 populations were down 83% compared to 2013). This ‘Eels in the
Classroom’ project will help more eels to reach their adult life-stage in the
Cambridgeshire Fens, contributing to their future viability.

The European eel. Image taken by Jack Perks, and accessed through:

Working in partnership with the EA and Over Primary School and Little Thetford Primary
School in the Old West river catchment, two Primary School classes will be given a hands-on experience in rearing endangered eels in their classrooms, releasing them into local rivers and streams after 5/6 weeks to help boost eel populations in the fens. In addition, the project will provide an opportunity for the children to learn about the fascinating life cycle of the eel, and the current environmental issues they face.

The life cycle of the European Eel- Illustration by Mark Garrison, accessed through:

We acknowledge the grant we have received from the Anglian Water Flourishing Environment Fund,a charitable fund managed by Cambridgeshire Community Foundation

New rules and top tips for septic tanks- 2020

In rural river catchments such as the Old Bedford and Middle Level catchment, septic tank effluent contains a wide variety of pollutants including pathogens, faecal bacteria, phosphorus (P), nitrogen (N), organic matter (OM), suspended solids (SS), pharmaceutical compounds and household detergents and chemicals that pose risks to fresh water resources. The extent of this impact depends on how well your septic system is maintained and if it is used properly.

Homeowners with septic tanks that discharge directly into ditches, streams, canals, rivers, surface water, drains or any other type of water course will need to replace or upgrade their drainage either when they sell their property or before 1 January 2020 whichever is sooner.

What are your options?

There are two main ways in which you can comply with the new regulations:

  1. Swap your septic tank for a sewage treatment plant – sewage treatment plants produce a cleaner form of water, and it’s considered clean enough to discharge straight to a watercourse.
  2. Install a drainage field or soakaway system – this will take the waste water from your septic tank, and disperse it safely into the ground without causing pollution.
    It’s not all doom and gloom, there’s still plenty of time to make the switch. And let’s face it, no one wants to think about the inhabitants of the local streams or rivers hanging out in the dirty water from septic tanks, so it’s a positive change for the environment.

The Environment Agency leaflet is below, if you struggle to read it try this link:  Small sewage discharge leaflet FINAL

Fascinated by the Fens? Share your knowledge, meet field experts and talk to researchers.

Come to  a Community Day on Friday 29 March in Ely to find out about the Scottish Soldiers who helped make (another word for dig!) our drained landscape.  Not much is known about these men and this project aims to piece together this forgotten story from the 1650s.

If you have any information about this fascinating local history please come along and share your stories or bring anything that might tell about the draining of the Fens, Maps, Articles, Family Stories, Objects.






Invasive Non Native Species update

 The GB Non Native Species Secretariat: October 2018 survey findings

The GB Non Native Species Secretariat has recently commissioned a report to look at public knowledge and attitudes towards non-native invasive species and discovered that “‘Species’ and ‘organisms’ meant little to many participants – ‘invasive animals and plants’ were more meaningful.”

The general public and targeted groups (anglers, boaters and exotic pet owners) were asked about their awareness levels, the impact they thought INNS could have on their activities and the actions they personally are taking to reduce the risk of spreading them. The finding from this have been used to shape a set of recommendations for the future of the Check, Clean, Dry Campaign (also in the report). The full report can be found here

Free Check, Clean Dry promotion materials are available here

 Brexit: plant and animal biosecurity – House of Lords Report October 2018 

The UK currently follows EU legislation on biosecurity, with decisions on implementing biosecurity measures made predominantly at an EU level. The UK also benefits from EU-wide intelligence gathering and disease notification systems, systems for tracing plant and animal movements, and coordinated research efforts.

This report  looks at what to be in place in order to reduce the threat of any EU new invasive organisms and manage the current ones post Brexit. It also identifies a number of opportunities for making our biosecurity more “bespoke” to the UK once we have left the EU.

ADA Biosecurity Policy & Procedures for IDBs

The Association of Drainage Authorities (ADA) has produced a template for a biosecurity policy and set of procedures to help internal drainage boards manage and reduce the risk of INNS spread. Click here for a model IDB Biosecurity Policy and Procedures.