Leaky dams

"Leaky dams" helping reduce flood risk in Harrop Brook and River Dean

image

"Leaky dams" at Pott Shrigley in Cheshire have been working well during Storm Barra over the past couple of days, helping to slow down the flow of flood water in Harrop Brook and the River Dean. 

Leaky by name, leaky by nature, even during high flows, "leaky dams" are built in small streams from natural materials - they will only let a certain amount of water through, slowly draining the trapped water to reduce the flood peak.  They are part of Natural Flood Management measures being implemented by a range of public sector and third sector organisations across the Mersey catchment to help reduce flood risk.

Funded by the Environment Agency, Mersey Rivers Trust installed the leaky dams at Pott Shrigley in March 2021, working in partnership with local farmers and landowners. Monitoring by Mersey Rivers Trust staff today (9 December) has shown that these new leaky dams have been able to hold back water in the headwaters of Harrop Brook and slowing down the flow of water into the downstream River Dean. 

Over the coming months, Mersey Rivers Trust will also be planting new trees at Pott Shrigley to complement the leaky dams.  Once established, the new trees will help take up water and allow more water to soak into the ground during flood conditions, further slowing the flow of water into the downstream river system.

News

Alt Weir Removal Planning
Plans are currently being explored for removal of the only major weir on the River Alt which is a barrier to fish migration
Mersey Valley Way: first National River Walk
The Mersey Valley Way along the River Mersey in Greater Manchester is the first designated national river walk in England.
Coppicing and dead hedging at Newgate Nature Reserve, Wilmslow
Tuesday 3 March. We're joining the Bollin Valley Partnership to undertake coppicing and dead hedging work at Newgate Nature Reserve, Wilmslow.
Battling the Birch at Lindow Common, Wilmslow
Wednesday 25 February. We're joining the Bollin Valley Partnership to help conserve the special habitat within Lindow Common in Wilmslow by removing self-seeded Birch.
Urban Riverfly Monitoring Upskill
Wednesday 18 February. Join us for a 1 hour online training webinar that builds skills in riverfly (invertebrate) monitoring, identification, data collection, and urban water quality.
River Mersey Guided Walk & Litter Pick on the Mersey Valley Way, Stockport
Friday 6 February 2026
Farm Demonstration Day - Rostherne, Cheshire
Tuesday 3 February. An event for farmers and landowners. Join us for a Farm Demonstration Day at Rostherne Mere, Cheshire to discover cost-effective ways to boost land productivity and filter water with ponds & reed beds!
Alt Crossens Newsletter
A look back at the projects and achievements in 2025 in the Alt Crossens catchment and what is happening in 2026
Outfall Safari Training for Citizen Scientists
Thursday 28 January. Join us for an online training session for the public to learn about outfall safari citizen science river surveys
River Mersey Guided Walk & Litter Pick: Mersey Valley Way, Stockport
Friday 23 January 2026
Mersey Valley Way
Mersey Rivers Trust is delighted that the River Mersey in Greater Manchester has been selected for the first national river walk
Litter Raft in Manchester
Adventure filmmaker Raphael Holt raising awareness of the litter & flytipping issues facing Manchester’s waterways
Manchester College Water Quality STEM Session
Soil and Water Health Day
Thursday 30th October
We are hiring ! Finance & Governance Manager
🌿 Join Mersey Rivers Trust and Help Make a Real Impact for Rivers, Wildlife and Communities! 🌿 
Vision for Sustainable Water Management in Liverpool City Region
Ambitious new vision to clean up rivers, prevent flooding and maintain water supplies
View All