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30.39

Tumbling Bay Weir

Amwell Loop ⚙ Structure
Lower Lee catchment • Ware • Hertfordshire • ID: 5263TH • Level
(32m ago) • 4 readings/hr • 140 views

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Current Level
30.386 mASD
▬ Steady
24h Max
30.411 mASD
24h Min
30.381 mASD
Typical Range
30.29 - 30.73
mASD
Highest Recorded
31.61 mASD
EA official record
31.42 in our data (since Nov 2016)
Current level is 96% of this
🚽 Sewage overflows nearby

Recent Water Levels

🌍 floodradar.co.uk
1 day

Flood predictions aren't generated for lock / structure gauges — their levels are driven by gate operation, not by catchment rainfall, so the forecast models would have no skill here.

Recent Readings

Falling · -1 cm over 5h
09 Oct 19:15 ▬ steady 30.386 mASD
09 Oct 19:00 ▲ +0.1 cm 30.385 mASD
09 Oct 18:45 ▬ steady 30.384 mASD
09 Oct 18:30 ▲ +0.3 cm 30.384 mASD
09 Oct 18:15 ▼ -0.6 cm 30.381 mASD
09 Oct 18:00 ▬ steady 30.387 mASD
09 Oct 17:45 ▲ +0.1 cm 30.387 mASD
09 Oct 17:30 ▬ steady 30.386 mASD
09 Oct 17:15 ▬ steady 30.386 mASD
09 Oct 17:00 ▲ +0.3 cm 30.385 mASD
09 Oct 16:45 ▬ steady 30.382 mASD
09 Oct 16:30 ▬ steady 30.383 mASD
09 Oct 16:15 ▬ steady 30.383 mASD
09 Oct 16:00 ▼ -0.3 cm 30.382 mASD
09 Oct 15:45 ▬ steady 30.385 mASD
09 Oct 15:30 ▲ +0.1 cm 30.385 mASD
09 Oct 15:15 ▼ -0.1 cm 30.384 mASD
09 Oct 15:00 ▼ -0.4 cm 30.385 mASD
09 Oct 14:45 ▼ -0.7 cm 30.389 mASD
09 Oct 14:30 30.396 mASD

Station Details

  • Monitoring Station: Tumbling Bay Weir
  • Watercourse: Amwell Loop
  • Nearest Town: Ware
  • County: Hertfordshire
  • Coordinates: 51°48'33"N 0°1'23"W (51.809124, -0.023037)
  • Open in: Google Maps · Apple Maps (opens your maps app)
  • Date Opened: 3 Sep 2014
  • Status: Active
  • Station Type: River level station
Technical details: references, datum, range, flow archive
  • Station Reference: 5263TH
  • RLOI id: 9047 (the EA's check-for-flooding station id)
  • EA Gauge ID: 5263TH-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: ⚙ Yes — lock, weir, sluice or pump
  • Catchment Area: Lower Lee
  • Datum: 0.000m AOD
  • Typical Range: 30.290 – 30.733 mASD
  • EA Cross-check: 30.39 mASD (EA at 9 Oct 19:15)

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

Nearby

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.

28 storm overflows are traced upstream of this gauge, the nearest 7.9 km away along the river. 0 report discharging now, 23 report not discharging, and for 5 the monitor is offline or has not reported, so their status is not known.

💧
Thames Water · into Rib · 7.9 km upstream along the river
7 spills · 10 hours in 2025
Not discharging now · last
💧
Thames Water · into Lea · 13.2 km upstream along the river
0 spills · 0 hours in 2025
Not discharging now · last
💧
Thames Water · into Lee · 16.0 km upstream along the river
6 spills · 58 hours in 2025
No live feed for this overflow
💧
Thames Water · into River Lee · 27.1 km upstream along the river
3 spills · 21 hours in 2025
Not discharging now · last
💧
Thames Water · into The River Rib · 29.4 km upstream along the river
3 spills · 5 hours in 2025
Not discharging now · last
💧
Thames Water · into Lee · 31.0 km upstream along the river
7 spills · 69 hours in 2025
Not discharging now · last
💧
Thames Water · into The River Quin · 35.8 km upstream along the river
7 spills · 93 hours in 2025
Not discharging now · last
💧
Thames Water · into The River Lee · 36.2 km upstream along the river
6 spills · 28 hours in 2025
Not discharging now · last

20 more further upstream, up to 46.6 km away along the river.

Nearby, connection not known

Within 6 km in a straight line, but the river map cannot say whether their water passes this gauge.

💧
Thames Water · into Toll House Stream · 4.8 km away in a straight line · no mapped watercourse close enough to be sure
5 spills · 38 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 30.73 m on about 8 days. This year so far: 0 days.

2026 0 days so far
2025 3 days
2024 18 days
2023 10 days
2022 16 days
2021 5 days
2020 6 days
2019 6 days
2018 8 days
2017 1 day

Counted from each day's highest reading. Days with missing or implausible readings are left out.

Flood history near this gauge

Official Environment Agency warnings issued since 2011 for the 10 flood areas linked to this gauge (nearest 1.9 km away).

4flood warnings 30flood alerts

Most recent flood warning: 7 Feb 2014 — River Beane at Hertford

Year by year
YearWarningsAlerts
2025 0 1
2024 0 6
2023 0 1
2021 0 4
2020 0 2
2019 0 1
2017 0 1
2016 0 3
2014 4 6
2013 0 2
2012 0 2
2011 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 Ware flood history.

Flood areas linked to this gauge

Flood warnings and alerts are issued for whole areas. These are the 10 areas linked to this gauge, nearest first.

Show 2 more

Frequently asked questions

Is the Amwell Loop at Tumbling Bay Weir flooding today?

The current level is 30.39m, which is within the typical range of 30.29 to 30.73m. Flooding is unlikely at this level.

Is the river level rising or falling at Tumbling Bay Weir?

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.

Why is the level slowly falling?

When little or no rain has fallen for a while, a river level gradually drops as the water stored in the ground and soil drains away with nothing to replace it. This is called baseflow recession and is normal in dry spells. Only about 5.2mm of rain has fallen nearby in the last 7 days, so the flow is being sustained mainly by groundwater. A gentle decline like this is expected and is not a sign of a problem — downstream gauges often recede a little faster than headwaters further upstream, and levels recover once rain returns.

What is a normal level for the Amwell Loop at Tumbling Bay Weir?

The typical range at this station is 30.29m to 30.73m, based on Environment Agency historical data. Levels above 30.73m 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 →