From NOT A LOT OF PEOPLE KNOW THAT

By Paul Homewood

h/t Dennis Ambler

Further to last week’s flooding in Monmouth. Dennis drew my attention to this Journal Article by Keith Kissack, which was published in 2001:

It’s also worth highlighting this comment in my article by Simon Browne:

Yesterday I asked Grok if the Wye and the Monnow were dredged in the past at Monmouth. This is his reply:

‘Historical Evidence of Dredging:

Pre-20th Century: The Wye was regularly dredged for navigation (to maintain depths for boats and trade), which had a secondary flood-prevention benefit. Monmouth was a port town until the 19th century, and dredging removed silt to keep the river navigable.

Mid-20th Century (1940s–1960s): After severe floods (e.g., 1947), the Wye River Board (predecessor to the EA) carried out mechanical dredging near Monmouth Bridge and downstream to clear gravel bars and improve flow. This was explicitly to reduce flood risk to the town center and low-lying areas like Chippenham and Wyesham.

1970s–1980s: Smaller-scale dredging occurred, particularly after the 1979 flood, to remove accumulated sediment at the Monnow-Wye confluence.

Key Source:

“Dredging operations were undertaken by the Wye River Board in the 1950s and 1960s to maintain channel capacity and reduce flood risk in Monmouth.”

— Monmouth Flood Alleviation Strategy Review (Environment Agency Wales, 2009)

2. River Monnow Dredging in Monmouth

Historical Evidence:

1950s–1970s: The Monnow was dredged upstream and at the confluence with the Wye to remove silt and gravel that restricted flow during high rainfall. This was part of joint operations with the Wye River Board.

Post-1998 Flood Response: After major flooding in 1998, limited dredging was carried out near Vauxhall Fields and the Monnow Bridge to improve conveyance.

Monmouth Town Council records confirm dredging in the early 2000s to clear blockages at the weir and sluice gates.

Key Source:

“Desilting and selective dredging of the River Monnow has been undertaken in the past, particularly in the reach through Monmouth, to maintain hydraulic capacity.”

— Monmouthshire County Council Flood Risk Management Plan (2016)

3. Why Dredging Stopped (or Reduced)

Environmental Regulations: From the 1990s onward, dredging became heavily restricted due to:

EU Habitats Directive and Water Framework Directive (2000) – the Wye is a Special Area of Conservation (SAC) due to salmon, otter, and lamprey populations.

Dredging disturbs riverbed habitats and increases downstream sedimentation.

Modern Alternatives: The EA now uses:

Natural flood management (tree planting, leaky dams upstream)

Flood walls and embankments (e.g., the Monmouth Flood Alleviation Scheme, completed 2015)

Gravel management (selective removal, not full dredging)

4. Recent Position (2020s)

No routine dredging occurs in Monmouth for flood prevention.

The Environment Agency (2023) states:

“Dredging is not a sustainable or environmentally acceptable solution for flood risk management on the Wye or Monnow in Monmouth.”

Instead, annual maintenance includes weed cutting, debris removal, and targeted gravel extraction where it poses a clear hydraulic risk.’