Flood Alert Issued for Upper River Colne and Radlett Brook in Hertfordshire

Alert Details

The Environment Agency has issued a flood alert for the Upper River Colne and Radlett Brook. This alert, classified as severity level 3, indicates that flooding is possible in the designated area. The alert was officially raised at 4:42 PM on February 15, 2026.

Affected Areas

The alert covers the Hertfordshire and North London region, specifically focusing on the Upper River Colne and Radlett Brook. According to the Environment Agency, the locations most likely to be affected include low-lying land and roads near rivers in the following areas:

• Waterside
• Lowbell Lane
• London Colney
• Warrengate Road

What You Should Do

Residents and commuters in the affected areas are advised to take the following precautions:

• Take care when traveling through the region.
• Avoid walking, cycling, or driving through flood water.
• Monitor local weather reports and river levels closely.

Expected Conditions

River levels remain high and are expected to lead to potential flooding. The primary hazard is the inundation of roads and low-lying land adjacent to the River Colne and Radlett Brook.

Timeline

The flood alert is effective from February 15, 2026, into February 16, 2026. The Environment Agency is monitoring the situation and expects to provide an update by 9:00 AM on February 16, 2026, or sooner if conditions change significantly.