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Mimmshall Brook water level

River gauge, Hertfordshire, United Kingdom

Directions

Within the normal range

Water level

0.27m Up 0.03 m over the last 24 hours

0 1 Highest onrecord 1.80 m Lowest on record 0.90 m

History

0.20.3mOct 12Oct 13Oct 15Oct 17Oct 19Bottom of normal range0.20.3mOct 12Oct 15Oct 19Bottom of normal range
0.20.30.4mSep 19Sep 26Oct 4Oct 11Oct 19Bottom of normal range0.20.30.4mSep 19Oct 4Oct 19Bottom of normal range
Water level Top of normal rangeBottom of normal range

What this means

Water levels are unremarkable at Mimmshall Brook, where the gauge shows 0.27 m.

The usual range here runs from 0.15 m to 1.80 m.

It is on the way up, by 0.03 m over the past 24 hours. The 30-day range is 0.23 m – 0.41 m.

Autumn rain usually starts to lift rivers again after the summer low.

Compared with the normal range the agency publishes for this gauge. How to read levels

Key numbers

Normal range
0.15 m – 1.80 m
Lowest and highest in 30 days
0.23 m – 0.41 m
Lowest and highest in 12 months
0.24 m – 0.30 m
Highest on record
1.80 mFebruary 7, 2014
Lowest on record
0.90 mJuly 2, 2004
Lowest on record
0.63 m below the lowest level on record

For anglers and canoeists

This is an ordinary level for the river: most put-ins, beats and weirs behave as they usually do.

Many angling and canoe clubs check gauges like this one before heading out.

About Mimmshall Brook

Mimmshall Brook

Mimmshall Brook is a 9.8 kilometres (6.1 mi) long stream (brook) in Greater London and Hertfordshire, England. Rising from two sources—one in Hertsmere, Hertfordshire, and the other in Arkley, London Borough of Barnet—the brook drains into a catchment area of 52 km2 (20 sq mi) at Water End Swallow Holes, Welham Green, North Mymms. It is a tributary of the River Colne.

Read more on Wikipedia

Text and image from Wikipedia and Wikimedia Commons, licensed under CC BY-SA.

Weather at the gauge

Rain in the last 3 days: 2.0 mm. Rain that falls upstream can take hours or days to show up at a river gauge.

18 Sun 13° 7° 3.7 mm, 91% Wind 20 km/h
19 Mon 14° 8° 2.4 mm, 95% Wind 12 km/h
20 Tue 12° 10° 9.0 mm, 59% Wind 11 km/h
21 Wed 13° 7° 3.6 mm, 49% Wind 20 km/h
22 Thu 13° 5° 0.7 mm, 48% Wind 17 km/h
23 Fri 10° 7° 38 mm, 76% Wind 36 km/h
24 Sat 10° 3° – Wind 22 km/h

Forecast: Open-Meteo

Sunrise 07:32 AM Sunset 06:01 PM Daylight 10 hr, 29 min First quarter 55%

Map

Other gauges on Mimmshall Brook

Gauge Level Compared with normal 24 hours Distance
North MymmsRiver gauge, Mimmshall Brook 0.38 m Very high +0.02 m 1.2 km

Nearby gauges

Gauge Level Compared with normal 24 hours Distance
London ColneyRiver gauge, River Colne 1.09 m Normal ±0 5.2 km
BorehamwoodRiver gauge, Borehamwood Brook 0.94 m Normal +0.05 m 6.4 km
RadlettRiver gauge, Radlett Brook 0.40 m Normal +0.03 m 7.3 km
New BarnetRiver gauge, Pymmes Brook 0.13 m Normal ±0 7.3 km
Colney StreetRiver gauge, River Ver 0.15 m Normal +0.01 m 8.2 km
WhetstoneRiver gauge, Dollis Brook 0.01 m Lowest on record ±0 9.5 km
WaterhallRiver gauge, River Lee 0.13 m Low +0.01 m 10 km
North FinchleyRiver gauge, Dollis Brook 0.26 m Normal ±0 10 km

Questions and answers

What is the typical range for Mimmshall Brook?

The Environment Agency gives a typical range of 0.15 m to 1.80 m for this gauge.

Is the river level the same as the depth of the water?

No. The reading is measured from a fixed zero mark at the gauge, so 0.27 m on the gauge does not mean the water is that deep.

What is the water level of Mimmshall Brook today?

On 19 Oct 2026, 04:15 BST, the water level was 0.27 m. Up 0.03 m over the last 24 hours.

Is Mimmshall Brook rising or falling?

Up 0.03 m over the last 24 hours. Up 0.04 m over the last 7 days.

Is the level of Mimmshall Brook normal?

Within the normal range. Compared with the normal range the agency publishes for this gauge.

What is the highest water level ever recorded at Mimmshall Brook?

The highest level on record is 1.80 m on February 7, 2014. The lowest is 0.90 m on July 2, 2004.

How often is this data updated?

The Environment Agency publishes a new reading every 15 minutes. This page refreshes within minutes of each update.

For specialists

Station codes, datum, parameters, data quality and downloads
Operator
Environment Agency
Station code
ea:2809TH (Agency page)
Coordinates
51.70690, -0.21782 (WGS84)
Vertical datum
station datum
Update interval
every 15 minutes
Licence
Open Government Licence v3.0. Contains Environment Agency data licensed under the Open Government Licence v3.0

Published series

ParameterLast valueTime (UTC)Quality
Water level 0.27 m 2026-10-19 03:15 Provisional

Download

Embed this gauge

Add a live card for this gauge to your website. It updates on its own and links back here.

How to cite

Environment Agency: Mimmshall Brook (ea:2809TH). Accessed October 19, 2026 via Nivelmap, https://nivelmap.com/en/united-kingdom/hertfordshire/mimmshall-brook

How we check values

Each reading is stored as published. We hold back values that jump faster than physically plausible and show the measurement time with every value.

Readings are provisional, can be delayed or wrong and are not a flood warning. Read the disclaimer