Removal of Dove Cliff weir - information page

Overview

Page created July 2019. Last updated 8 April 2022.

Since our last update in November 2021, we have continued with some ongoing land reinstatement works and started post-construction landscaping. With spring on the horizon, the wildflower seed mix, sown by our partners at Transforming the Trent Valley, has developed nicely. We are confident that it will continue to grow as expected through the summer and are ready to reseed where necessary once we see the coverage later in the year.

Dove Cliff weir

Following the completion of the weir removal works in October 2021, the channel now consists of a more natural river bend, with a deep faster flowing section on the outside and a shallower flowing section on the inside, as shown in the images below. The mill fleam has been reconnected on the outside of the bend to ensure the flows are maintained.

Below is an aerial photograph looking down at the new river alignment where the weir used to be, adjacent to the aerial view design illustration.

Above Left: August 2021 aerial photograph of completed permanent works. Above Right: Artist impression of completed project.

Landscaping

Our landscaping contractors, ATM, have planted over 300 small trees and shrubs to replace those removed before the works started, and to improve the local biodiversity around the restored river channel. The native woodland tree mix is primarily Alder, Oak, Black Poplar and Crack Willow, whilst the native shrub mix is primarily Hawthorn, Hazel and Holly. ATM is contracted to look after the planting for the next five years, ensuring that the trees and shrubs are looked after until they are established. To help them with this we have fenced off these very specific areas from livestock. A small section of planting will happen next winter once we have finished the last reinstatement of the fields.

Reinstatement works

Due to finishing on site slightly later in the year than anticipated, our contractor, Stonbury, could not complete some of the field reinstatement to the quality that we were fully happy with. The land had unfortunately become too wet to effectively place the soil, so we have asked them to come back to finish this work in the coming weeks once the ground has dried out sufficiently. We anticipate this will be localised work for no more than a week and we will give landowners and local residents advance notice of these dates once confirmed.

Archaeology

The analysis of the archaeology discovered on site is still ongoing, with the final report expected in late summer 2022. We will make this publicly available when it is completed and are looking forward to finding out more about the history of the location.

Monitoring

We have now entered into the important post construction monitoring phase of the project, with elements of that continuing for a number of years. It includes flow and water level monitoring in the river, both upstream and downstream of the main site location, as well as further flow monitoring in the mill fleam. The groundwater levels will also continue to be monitored, particularly how they link with Podmores Pools upstream of the site location, and the progress of the gravel bars and banks of the main channel.

Open house event in 2022

We are intending to have a public open house event next to the river in summer 2022, to give people an opportunity to see the completed project. We will provide further details on this event in future updates.

Benefits of weir removal

Weirs were historically designed and installed to control water and at that time the environmental impacts of their installation weren’t fully considered or understood.  It was later discovered that they altered natural functions of rivers and their connection with the floodplain, impacting on water quality and adversely affecting aquatic ecology and the wider surrounding environment. Removing a weir improves water quality by allowing water to flow naturally.

Fish and invertebrate species also greatly benefit from weir removal as weirs act as barriers to their movement. Weir removal benefits all aspects of aquatic ecology, including recovery of the riverbed and banks, and development of a more diverse habitat.  A greater diversity of fish and invertebrate species is documented both up and downstream following weir removal.  We are already seeing the benefits of weir removal upstream of the site with the formation of gravel bars and improved habitat for invertebrates and spawning fish as shown below.

Photographs - (Above left) Exposed river sediment is important habitat for diverse communities of beetle, birds and plant species. (Above right) Dove Cliff weir with salmon attempting passage.

Outdated weirs which no longer serve a purpose frequently fall into disrepair and become economically unfeasible to maintain and replace. The public safety risk associated with these types of structures should not be underestimated.  Every year there are numerous unfortunate incidents of people drowning in the dangerous conditions around weirs.

Background

We have removed Dove Cliff weir (pictured below) to improve biodiversity and improve fish passage through the entire Dove catchment. Dove Cliff weir was structurally assessed in 2016 and sections were found to be in a poor condition. This led to all options for managing the weir being investigated.

The best solution for fish passage in our rivers is to remove barriers, such as weirs and sluices. This is particularly important when they are in poor condition, can cost a lot of money to maintain and no longer serve a functional purpose.

Fish passes alone do not improve the habitat required for fish to spawn and grow. However, removing weirs does as it allows the sediments within the river to deposit naturally creating the right river environments.

Frequently asked questions

Will the removal of the weir effect the water levels in the river?

With Dove Cliff weir removed, the water level upstream of the weir will drop. The water level is expected to drop by approximately 1 metre immediately upstream of the weir. Due to the natural slope in the riverbed, the further upstream you go the less change in water level you will see. There will be no change in river level upstream of Rolleston Brook where it enters the River Dove.

The reduction in water level will be a benefit to the environment as it allows the river to function in a natural way, creating both shallow and deep sections within the river. Shallow river sections are just as important to biodiversity, especially fish, as they provide the right conditions for small fish to grow after they hatch. 

How will flows in the mill fleam be affected by this project?

Maintaining a similar flow split between the main river and the mill fleam (mill leat) was an important design criteria for this project. With the construction work now complete, we are monitoring the flows in both the mill fleam and the main river to confirm this and will continue to undertake monitoring across the full range of flows in the Dove.

Further information

As we have now completed construction all future updates to this page will be on an ad-hoc basis when there is information that is deemed to be of public interest and value.

Look out for #Dovecliff updates on our twitter feed too @EnvAgencyMids.

Thank you for visiting our project information page.

External website links that may be of interest

https://yearofthesalmon.org/
https://www.damremoval.eu/
https://www.worldfishmigrationday.com/home