Progress is being made in a bid to reduce flooding in an area of Weymouth.

Radipole Lake is undergoing a series of works as a range of parties have drawn up plans that they hope will reduce the recent flooding to the area.

As previously reported, concerns were raised after persistent flooding to the Radipole area following a wet winter, with a petition started by Dorset Council and Weymouth Town Councillor Matt Bell in order to get the lake dredged.

Since then, stakeholders involved in the care of the site, in accordance with a Water Level Management Plan, have met to review it. The current plan was first developed in 2009 on behalf of the former Weymouth and Portland Borough Council.

The 2009 plan sets out how water levels within the Site of Special Scientific Interest (SSSI) should be managed, whilst also meeting the designation interest features regulated by Natural England.

Following a meeting between Dorset Council, Wessex Water, the RSPB, Weymouth Town Council and the Environment Agency, a number of decisions were made:

  • Wessex Water has added the clearance of 15 surface water sewer outlets to its maintenance programme for August 2024. This will help improve land drainage
  • The Coastal Risk Management team has amended its work programme to remove the stop logs at Westham Bridge earlier this year
  • The Coastal Risk Management team is arranging installation of viewable water level gauges at Westham Bridge
  • RSPB is bidding for Countryside Stewardship funding which would enable a desilting study. The scope of the study is not yet known but a brief will be drafted and sent to Natural England for review
  • The SSSI will be surveyed soon, these results will support the study and feasibility plan. The studies proposed will be useful to put towards a future WLMP refresh and any new plan will need to include this information. 
  • A ten-year structural assessment of Westham Bridge will be undertaken in 2024/25. Ramboll will be undertaking the survey.

Why Westham Bridge is important to the Water Level Management Plan?

  • Westham Bridge is an embankment dam structure preventing tidal water from Weymouth Harbour entering Radipole Lake
  • Eight circular culverts run through the structure with four at a lower level in the centre of the structure with electronically operated penstocks. Four are at a higher level and have flap valves. The flap valves are in pairs on either side of the 4 central penstocks. These flaps and penstocks regulate the passage of water between the lake and the harbour
  • The flap valves open when the tide level recedes low enough for lake flow pressures to open the flaps
  • The automated penstocks will only open when the lake level is above its minimum set level and the harbour level is below its minimum set level. Manual override can be carried out on site, in exceptional circumstances
  • The Water Level Management Plan (WLMP) requires the lake to always be above a minimum level for bird and wetland management. It also requires the lake set level to be higher in summer than in winter. The lake water level in summer is raised by installing oak stop logs on the lake side of the bridge in front of the tidal flap valves.
  • Once the lake level rises above the stoplog level the water flows over the oak logs and dissipates through the tidal flaps, tide allowing    

A spokesperson for Dorset Council said: “A stakeholder working group has been established and is meeting regularly. A review of the 2009 Water Level Management Plan has been undertaken and future sustainable interventions are being considered. At the most recent working group meeting actions have been agreed and are being progressed.”

A Wessex Water spokesperson said: “Drainage systems carrying run-off when it rains are often interconnected so we work closely with Dorset Council and others to help when flooding occurs and advise on how future flood risk can be managed.

“This maintenance work on our surface water outfalls, which carry rainwater, forms part of the council’s water level management plan for Radipole Lake.”

A spokesperson for the RSPB confirmed that they have bid for stewardship.