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Live levels from 19 monitoring stations across Buckinghamshire, Essex, Greater London, Hertfordshire, Surrey…, updated every 15 minutes.
| Station | Level now | Status | ||
|---|---|---|---|---|
| London Colney | 1.08 mASD 1h ago | Normal | ||
| 11.2 km by river | ||||
| Watfordstructure | 0.19 mASD 1h ago | Normal | ||
| 8.4 km by river | ||||
| Moor Lane | 7.44 mASD 28h ago | old reading | ||
| Station | Level now | Status | ||
|---|---|---|---|---|
| Continues from the section above: 12.6 km by river below Moor Lane | ||||
| Denham Colne | 0.14 mASD 1h ago | Normal | ||
| 880 m by river | ||||
| Willowbankstructure | 0.85 mASD 1h ago | Normal | ||
| 4.1 km by river | ||||
| Iver, Clisbys Bridge | 0.36 mASD 1h ago | Normal | ||
| downstream, distance by river not measured | ||||
| Farlows Bridge | 0.39 mASD 1h ago | Normal | ||
| downstream, distance by river not measured | ||||
| West Drayton | 0.41 mASD 1h ago | Normal | ||
| downstream, distance by river not measured | ||||
| Thorney Mill Road, West Drayton (Temporary) | 0.07 m 1h ago | Low | ||
| 4.6 km by river | ||||
| Stanwell Mill | 0.67 mASD 1h ago | Normal | ||
| 4.3 km by river | ||||
| Staines Trading Estate | 1.18 mASD 1h ago | Normal | ||
| Station | Level now | Status | ||
|---|---|---|---|---|
| Marsden | 0.22 m 1h ago | Low | ||
| 11.6 km by river | ||||
| Huddersfield Longroyd Bridge | 0.25 m 1h ago | Normal | ||
| 5.2 km by river | ||||
| ICI Colne | 0.13 m 1h ago | Low | ||
| 2.0 km by river | ||||
| Colne Bridge | 0.31 m 1h ago | Normal | ||
| Station | Level now | Status | ||
|---|---|---|---|---|
| Great Yeldham | 0.09 mASD 21h ago | old reading | ||
| 5.7 km by river | ||||
| Poole Street | 0.08 mASD 1h ago | Normal | ||
| downstream, distance by river not measured | ||||
| Earls Colne | 0.13 mASD 1h ago | Normal | ||
| 16.0 km by river | ||||
| Lexden | 0.20 mASD 1h ago | Normal | ||
Stations are listed from source to mouth as the water flows, traced on the river map (OS Open Rivers) and the Environment Agency’s own links between its gauges. A distance “by river” is along the river, and is shown only where the map traces the path.
Contains OS data © Crown copyright and database rights 2026.
Streams and rivers with a gauge whose water joins the Colne above one of its gauges, from the source down. Named streams without a gauge that have a page here are listed at the end.
Joins the Colne above London Colney, its highest gauge, no more than 8.2 km by river above London Colney.
| Mimmshall Brook | 0.31 mASD 1h ago | Normal |
| 1.3 km by river | ||
| North Mymms | 0.40 mASD 1h ago | Normal |
Its water passes every gauge on the Colne, from London Colney down.
Joins the Colne between London Colney and Watford, no more than 6.2 km by river above Watford.
| Markyatestructure | -0.04 mASD 1h ago | Low |
| downstream, distance by river not measured | ||
| Redbournstructure | 0.04 mASD 1h ago | Normal |
| 14.6 km by river | ||
| Colney Street | 0.14 mASD 1h ago | Normal |
Its water passes Watford and every gauge below it on the Colne. It does not pass London Colney or the gauges above it.
Joins the Colne between London Colney and Watford, no more than 9.6 km by river above Watford.
| Radlett | 0.41 mASD 1h ago | Normal |
Its water passes Watford and every gauge below it on the Colne. It does not pass London Colney or the gauges above it.
Joins the Colne between Moor Lane and Denham Colne, no more than 11.9 km by river above Denham Colne.
| Chesham | 0.33 mASD 1h ago | Normal |
| 15.3 km by river | ||
| Rickmansworthstructure | 0.09 mASD 1h ago | Normal |
Its water passes Denham Colne and every gauge below it on the Colne. It does not pass Moor Lane or the gauges above it.
Joins the Colne between Denham Colne and Willowbank, no more than 1.3 km by river above Willowbank.
| Missenden | 0.10 mASD 1h ago | Normal |
| 19.3 km by river | ||
| Denham Lodgestructure | 0.07 mASD 1h ago | Normal |
Its water passes Willowbank and every gauge below it on the Colne. It does not pass Denham Colne or the gauges above it.
Joins the Colne between Thorney Mill Road, West Drayton (Temporary) and Stanwell Mill, no more than 5.8 km by river above Stanwell Mill.
| Uxbridge, Fountains Mill | 0.68 mASD 1h ago | Normal |
| 5.1 km by river | ||
| Yiewsley | 0.76 mASD 1h ago | Normal |
Its water passes Stanwell Mill and every gauge below it on the Colne. It does not pass Thorney Mill Road, West Drayton (Temporary) or the gauges above it.
Below Staines Trading Estate, its water next reaches Staines, a gauge on River Thames, 810 m by river downstream.
Joins the Colne between Marsden and Huddersfield Longroyd Bridge, no more than 7.3 km by river above Huddersfield Longroyd Bridge.
| Slaithwaite | 0.16 m 1h ago | — |
Its water passes Huddersfield Longroyd Bridge and every gauge below it on the Colne. It does not pass Marsden or the gauges above it.
Joins the Colne between Marsden and Huddersfield Longroyd Bridge, no more than 2.7 km by river above Huddersfield Longroyd Bridge.
| Huddersfield Royd Street | 0.06 m 1h ago | Normal |
Its water passes Huddersfield Longroyd Bridge and every gauge below it on the Colne. It does not pass Marsden or the gauges above it.
Joins the Colne between Huddersfield Longroyd Bridge and ICI Colne, no more than 3.8 km by river above ICI Colne.
| Fenay Bridge | 0.10 m 1h ago | Low |
Its water passes ICI Colne and every gauge below it on the Colne. It does not pass Huddersfield Longroyd Bridge or the gauges above it.
Joins the Colne between Huddersfield Longroyd Bridge and ICI Colne, no more than 3.2 km by river above ICI Colne.
| Huddersfield Willow Lane | 0.01 m 1h ago | Normal |
Its water passes ICI Colne and every gauge below it on the Colne. It does not pass Huddersfield Longroyd Bridge or the gauges above it.
Joins the Colne between Huddersfield Longroyd Bridge and ICI Colne, no more than 4.6 km by river above ICI Colne.
| Holmbridge | 0.45 m 1h ago | Normal |
| 13.7 km by river | ||
| Queen's Mill | 0.28 m 1h ago | Normal |
Its water passes ICI Colne and every gauge below it on the Colne. It does not pass Huddersfield Longroyd Bridge or the gauges above it.
Below Colne Bridge, its water next reaches Heaton Lodge, a gauge on River Calder, 930 m by river downstream.
No gauged tributary joins the Colne above Lexden on the river map. Streams without a gauge are not counted here.
Below Lexden, its water next reaches Colne Barrier, 12.9 km by river downstream.
Tributaries and where they join are traced on the river map (OS Open Rivers, edition 2026-04) and the Environment Agency’s links between its gauges. The map holds distances between gauges, not the junctions themselves, so a junction is placed between two gauges, and no further up than the tributary’s own lowest gauge. Contains OS data © Crown copyright and database rights 2026.
5 storm overflows are traced upstream of Staines Trading Estate, the Colne’s lowest gauge on the river map: on the Colne itself, on its gauged tributaries, and on smaller streams that join above there.
Official figures for 2025, for the overflows traced upstream of Staines Trading Estate: 152 spills over 2,309 hours in total, across all 5.
Each overflow is listed in the stretch above the first gauge its water reaches, from the source down, as on the Gauges tab. A stretch of the Colne includes the smaller streams that join it there.
1 other overflow within 3 km of these gauges is placed below the Colne’s lowest gauge or on another river, so not listed.
93 storm overflows are traced upstream of Colne Bridge, the Colne’s lowest gauge on the river map: on the Colne itself, on its gauged tributaries, and on smaller streams that join above there.
Official figures for 2025, for the overflows traced upstream of Colne Bridge: 2,520 spills over 12,801 hours in total, across all 93.
Each overflow is listed in the stretch above the first gauge its water reaches, from the source down, as on the Gauges tab. A stretch of the Colne includes the smaller streams that join it there. Where a stretch or a tributary has more than 4, the 3 discharging now or nearest its gauge are listed, the rest are counted, and every one is in that gauge’s “Upstream of here” list. Show every overflow in every stretch →
and 19 more: show all 22 overflows on this stretch → All above Huddersfield Longroyd Bridge, nearest first →
and 30 more: show all 33 overflows on this stretch → All above ICI Colne, nearest first →
and 2 more: show all 5 overflows on this stretch → All above Fenay Bridge, nearest first →
and 26 more: show all 29 overflows on this stretch → All above Queen's Mill, nearest first →
Within 3 km of one of the Colne’s gauges in a straight line, but the river map cannot say whether their water reaches it.
10 more near these gauges whose connection is not known.
7 other overflows within 3 km of these gauges are placed below the Colne’s lowest gauge or on another river, so not listed.
13 storm overflows are traced upstream of Lexden, the Colne’s lowest gauge on the river map: on the Colne itself, on its gauged tributaries, and on smaller streams that join above there.
Official figures for 2025, for the overflows traced upstream of Lexden: 127 spills over 582 hours in total, across the 12 that have a figure. 1 had no usable monitor data that year.
Each overflow is listed in the stretch above the first gauge its water reaches, from the source down, as on the Gauges tab. A stretch of the Colne includes the smaller streams that join it there.
Within 3 km of one of the Colne’s gauges in a straight line, but the river map cannot say whether their water reaches it.
A status is the water company’s own monitor: it says whether an overflow is discharging, never how much or why, and a spill does not by itself explain a change in a river level. A status older than two hours is shown as unknown. Annual figures are the official returns: 12/24-hour spills for England and Wales, overflow events for Scotland (Scottish Water counts differently, so the two cannot be compared). “No data” means the monitor produced no usable data that year, not zero. Overflows are placed on OS Open Rivers (edition 2026-04), which leaves out many small channels: an overflow the map cannot place may still drain here. Contains OS data © Crown copyright and database rights 2026. Sewage in Britain’s rivers →
Live status: © Thames Water storm overflow activity data, licensed under CC BY 4.0. Live status: © Yorkshire Water storm overflow activity data, licensed under CC BY 4.0. Live status: © Anglian Water storm overflow activity data, licensed under CC BY 4.0. Annual figures for England: Environment Agency Event Duration Monitoring return, © Environment Agency copyright and/or database right, Open Government Licence v3.0.
Dated samples taken by the Environment Agency, not live readings. Results are published days to months after the sample is taken, and many points are sampled only a few times a year, or have not been sampled for years.
Sampled most recently, anywhere on these rivers and their streams:
40 sampling points on the River Colne and the streams that join it above Staines Trading Estate, and below it. 22 have a sample from the last 12 months; 28 have any sample banked.
| Where, from the source down | Sampling points | Newest sample |
|---|---|---|
| River Ver and its streamsjoins the Colne above Watford | 3 points2 sampled | 3 Sep 2026 |
| Mimmshall Brook and its streamsjoins the Colne above London Colney | 2 points0 sampled | none banked |
| Above London Colney | 4 points3 sampled | 4 Sep 2026 |
| River Chess and its streamsjoins the Colne above Denham Colne | 7 points5 sampled | 18 Sep 2026 |
| Above Watford | 2 points1 sampled | 18 May 2026 |
| Above Moor Lane | 4 points3 sampled | 20 Jul 2026 |
| Above Denham LodgeRiver Misbourne · joins the Colne above Willowbank | 5 points4 sampled | 4 Sep 2026 |
| Fray's River and its streamsjoins the Colne above Stanwell Mill | 3 points1 sampled | 12 Aug 2026 |
| Above Denham Colne | 3 points2 sampled | 28 Sep 2026 |
| Above Willowbank | 1 point | 7 Sep 2026 |
| Above Farlows Bridge | 1 point | 17 Aug 2026 |
| Above Thorney Mill Road, West Drayton (Temporary) | 1 point | 5 Dec 2025 |
| Above Stanwell Mill | 1 point | 7 Dec 2023 |
| Above Staines Trading Estate | 2 points | 5 Dec 2024 |
| Below the lowest gauge | 1 point | 24 Jul 2026 |
40 sampling points on the River Colne and the streams that join it above Colne Bridge, and below it. 5 have a sample from the last 12 months; 8 have any sample banked.
| Where, from the source down | Sampling points | Newest sample |
|---|---|---|
| River Holme and its streamsjoins the Colne above ICI Colne | 15 points2 sampled | 4 Jun 2026 |
| Above Marsden | 2 points | 17 Sep 2026 |
| Above Huddersfield Longroyd Bridge | 11 points1 sampled | 4 Dec 2024 |
| Above Fenay BridgeFenay Beck · joins the Colne above ICI Colne | 4 points1 sampled | 4 Aug 2026 |
| Above ICI Colne | 6 points2 sampled | 1 Dec 2025 |
| Above Colne Bridge | 1 point0 sampled | none banked |
| Below the lowest gauge | 1 point0 sampled | none banked |
35 sampling points on the River Colne and the streams that join it above Lexden, and below it. 12 have a sample from the last 12 months; 13 have any sample banked.
| Where, from the source down | Sampling points | Newest sample |
|---|---|---|
| Above EARLS COLNE FGS | 12 points5 sampled | 17 Sep 2026 |
| Above Lexden | 10 points3 sampled | 17 Sep 2026 |
| Above Poole Street | 11 points3 sampled | 17 Sep 2026 |
| Below the lowest gauge | 2 points | 15 Sep 2026 |
England's samples only. Each count opens the list of those points, nearest first, with the date of each one’s latest sample (the gauge’s “Upstream of here” list).
FloodRadar does not grade these results: there is no overall score, and official river classifications are a separate dataset. A sample taken downstream of an overflow does not by itself show where anything in it came from. River connections and distances are traced on OS Open Rivers (edition 2026-04), which leaves out many small channels.
Water samples: Environment Agency Water Quality Archive, © Environment Agency and/or database right 2026, Open Government Licence v3.0.
Contains OS data © Crown copyright and database rights 2026.
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