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0.11

Horton Mill

Colne Brook
Colne (Lower) catchment • Horton • Windsor and Maidenhead • ID: 2897BTH • Level
(33m ago) • 4 readings/hr • 128 views

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⤴ Unusual rise — FloodRadar+Top 1% rise rate for this gauge.
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Current Level
0.108 mASD
▬ Steady
24h Max
0.123 mASD
24h Min
0.107 mASD
Typical Range
0.12 - 0.42
mASD
Highest Recorded
0.48 mASD
EA official record
A 1.31 reading (22 Jun 2026) sits in our unverified raw history and is not treated as the record
Current level is 22% of this
🚽 Sewage overflows nearby

Recent Water Levels

🌍 floodradar.co.uk
1 day

Recent Readings

Falling · -0.8 cm over 5h
09 Oct 22:30 ▬ steady 0.108 mASD
09 Oct 22:15 ▲ +0.1 cm 0.108 mASD
09 Oct 22:00 ▼ -0.1 cm 0.107 mASD
09 Oct 21:45 ▼ -0.1 cm 0.108 mASD
09 Oct 21:30 ▼ -0.1 cm 0.109 mASD
09 Oct 21:15 ▼ -0.1 cm 0.110 mASD
09 Oct 21:00 ▲ +0.1 cm 0.111 mASD
09 Oct 20:45 ▼ -0.2 cm 0.110 mASD
09 Oct 20:30 ▼ -0.2 cm 0.112 mASD
09 Oct 20:15 ▲ +0.1 cm 0.114 mASD
09 Oct 20:00 ▼ -0.1 cm 0.113 mASD
09 Oct 19:45 ▬ steady 0.114 mASD
09 Oct 19:30 ▼ -0.1 cm 0.114 mASD
09 Oct 19:15 ▬ steady 0.115 mASD
09 Oct 19:00 ▲ +0.1 cm 0.115 mASD
09 Oct 18:45 ▼ -0.1 cm 0.114 mASD
09 Oct 18:30 ▬ steady 0.115 mASD
09 Oct 18:00 ▬ steady 0.115 mASD
09 Oct 17:45 ▼ -0.1 cm 0.115 mASD
09 Oct 17:30 0.116 mASD

Station Details

  • Monitoring Station: Horton Mill
  • Watercourse: Colne Brook
  • Nearest Town: Horton
  • County: Windsor and Maidenhead
  • Coordinates: 51°28'18"N 0°31'52"W (51.471740, -0.531230)
  • Open in: Google Maps · Apple Maps (opens your maps app)
  • Date Opened: 15 Nov 2018
  • Status: Active
  • Station Type: River level station
Technical details: references, datum, range, flow archive
  • Station Reference: 2897BTH
  • RLOI id: 9297 (the EA's check-for-flooding station id)
  • EA Gauge ID: 2897BTH-level-stage-i-15_min-mASD
  • Parameter: Level
  • Unit: mASD
  • Typical rise rate: 1 cm/hr (p95 sustained over 90 days)
  • Typical data delay: ~22 min (measured reading→publication lag)
  • Tidal: No
  • Lock / structure: No
  • Catchment Area: Colne (Lower)
  • Typical Range: 0.120 – 0.420 mASD
  • EA Cross-check: 0.11 mASD (EA at 9 Oct 22:15)

Geographic coordinates may reflect the access point for the gauge, and not the precise location in the watercourse that it is taking readings from.

Nearby Stations

Gauges connected to this river, and others nearby. A distance “by river” follows the river on the map; any other is in a straight line.

Connected upstream

Connected downstream

Same river system, separate branch

Distances by river: OS Open Rivers. Contains OS data © Crown copyright and database rights 2026.

💧 Storm overflows upstream of this gauge

Storm overflows whose water reaches this gauge on the mapped river network, nearest first by distance along the river. The status is each water company's monitor: it says whether an overflow is discharging, not how much or what it contains.

6 storm overflows are traced upstream of this gauge, the nearest 7.0 km away along the river. 0 report discharging now, 6 report not discharging.

💧
Thames Water · into Colne Brook · 7.0 km upstream along the river
0 spills · 0 hours in 2025
Not discharging now · last
💧
Thames Water · into Misbourne · upstream (distance along the river not measured)
13 spills · 167 hours in 2025
Not discharging now · last
💧
Thames Water · into The River Chess · upstream (distance along the river not measured)
7 spills · 58 hours in 2025
Not discharging now · last
💧
Thames Water · into Misbourne · upstream (distance along the river not measured)
88 spills · 1,605 hours in 2025
Not discharging now · last
💧
Thames Water · into River Colne · upstream (distance along the river not measured)
35 spills · 455 hours in 2025
Not discharging now · last
💧
Thames Water · into Potters Bar Brook · upstream (distance along the river not measured)
9 spills · 25 hours in 2025
Not discharging now · last

1 other overflow within 6 km is downstream of this gauge or on another branch of the river network, so it is not listed.

These are the water companies' monitor statuses; a spill does not by itself explain a change in the gauge level. River connections and distances are traced on OS Open Rivers (edition 2026-04), which leaves out many small channels. Explore the sewage map →

Contains OS data © Crown copyright and database rights 2026.

Rainfall & Weather

Loading rainfall and weather data...

How often this river runs high

In a typical year this gauge reaches its typical high of 0.42 m on about 1 day. This year so far: 0 days.

2026 0 days so far
2025 0 days
2024 2 days
2023 0 days
2022 0 days
2020 0 days patchy data

Counted from each day's highest reading. Days with missing or implausible readings are left out, so a year marked patchy may have run high more often than shown.

Flood history near this gauge

Official Environment Agency warnings issued since 2009 for the 3 flood areas linked to this gauge (nearest 0.7 km away).

15flood warnings 29flood alerts

Most recent flood warning: 2 Mar 2024 — Colne Brook at Iver

Year by year
YearWarningsAlerts
2026 0 3
2025 0 3
2024 3 10
2023 1 2
2021 3 1
2020 1 3
2019 2 1
2018 0 1
2016 1 1
2014 4 2
2012 0 1
2009 0 1

Warnings apply to a whole flood area, not necessarily this exact spot. Years before 2006 aren't covered by the EA's historic record. See also the Horton flood history.

Flood areas linked to this gauge

Flood warnings and alerts are issued for whole areas. These are the 3 areas linked to this gauge, nearest first.

Frequently asked questions

Is the Colne Brook at Horton Mill flooding today?

The current level is 0.11m, which is below the typical range. Flooding is very unlikely at this level.

Is the river level rising or falling at Horton Mill?

Based on the most recent readings, the level is currently steady. The chart above shows the last 12 hours of measurements by default (up to 7 days), updated roughly every 15 minutes.

What is a normal level for the Colne Brook at Horton Mill?

The typical range at this station is 0.12m to 0.42m, based on Environment Agency historical data. Levels above 0.42m are higher than usually seen and may indicate a flood risk.

How often is this river level data updated?

Readings are supplied by the Environment Agency gauge. FloodRadar checks for updates roughly every 15 minutes; the timestamp above shows how recent the latest available reading is.

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📮 Flood risk by postcode near this gauge

Postcodes within 5 km with properties in the Environment Agency’s rivers-and-sea flood-risk bands:

Check any UK postcode’s flood risk →

🏠 Buying or renting around here? Get the Property Flood-Risk Report for any English postcode — official risk band, recorded floods, warning history, river behaviour and nearby storm overflows. £19 one-off. Learn more →