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Mardock water level

River gauge, River Ash, Hertfordshire, United Kingdom

Directions

Right now

Normal for mid-October

Water level

0.10m Steady over the last 24 hours

0.0 0.5 1.0 1.5 Highest onrecord 1.61 m Lowest on record 0.06 m

History

History
0.100.130.150.18mOct 12Oct 13Oct 15Oct 17Oct 19Bottom of normal range0.100.130.150.18mOct 12Oct 15Oct 19Bottom of normal range
0.100.130.150.18mSep 19Sep 26Oct 4Oct 11Oct 19Bottom of normal range0.100.130.150.18mSep 19Oct 4Oct 19Bottom of normal range
0.30.50.8mOct 2025Jan 2026Apr 2026Jul 2026Oct 2026Top of normal rangeBottom of normal range0.30.50.8mOct 2025Apr 2026Oct 2026Top of normal rangeBottom of normal range
0.10.20.30.4mJanMarMayJulSepNov20260.10.20.30.4mJanAprJulOct2026

20252026

Water level Normal range (10–90 %) Top of normal rangeBottom of normal range

What this means

The River Ash at Mardock is at 0.10 m, in the normal range for mid-October.

The median for mid-October is 0.11 m, based on 21 years of readings, so the river level is 0.01 m below typical. A year ago it stood at 0.11 m as well.

It has barely moved over the past 24 hours. In the last month it has stayed between 0.10 m and 0.11 m.

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

Compared with 21 years of daily readings for this time of year. How to read levels

Key numbers

Median for this date
0.11 m0.01 m below the median for this date
Normal for this date
0.09 m – 0.17 m8 years in 10 fall in this range (21 years of records)
Normal range
0.10 m – 0.80 m
Same day last year
0.11 m0.00 m
Lowest and highest in 30 days
0.10 m – 0.11 m
Lowest and highest in 12 months
0.10 m – 0.39 m
Highest on record
1.61 mOctober 21, 2001
Lowest on record
0.06 mSeptember 25, 1997

Fishing and paddling

Paddlers and anglers can expect the river much as they know it, though a heavy shower upstream can change that within hours.

Flood alerts and warnings come from the Environment Agency.

About the River Ash

River Ash, Surrey

The River Ash is a small, shallow river in Surrey, England. Its course of 10 kilometres (6.2 mi) is just outside Greater London. Work has been carried out to re-align, clear and build up a small, Littleton head of water and create two backwaters. One backwater dates to the medieval period; the other to the 1990s. It flows as one of the six distributaries of the River Colne from the south of Staines Moor immediately south of the Staines Bypass eastwards through the rest of the borough of Spelthorne before meeting the River Thames.

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: 1.5 mm. Rain that falls upstream can take hours or days to show up at a river gauge.

18 Sun 13° 7° 2.7 mm, 99% Wind 26 km/h
19 Mon 14° 9° 8.1 mm, 94% Wind 14 km/h
20 Tue 13° 11° 8.7 mm, 65% Wind 14 km/h
21 Wed 13° 7° 3.0 mm, 43% Wind 23 km/h
22 Thu 14° 5° 0.5 mm, 68% Wind 19 km/h
23 Fri 10° 7° 41 mm, 75% Wind 38 km/h
24 Sat 10° 3° – Wind 24 km/h

Forecast: Open-Meteo

Sunrise 07:31 AM Sunset 06:00 PM Daylight 10 hr, 28 min First quarter 56%

Map

Other gauges on the River Ash

Gauge Level Compared with normal 24 hours Distance
Little HadhamRiver gauge, River Ash 0.02 m Normal ±0 9.1 km
Furneux PelhamRiver gauge, River Ash 0.14 m Very low +0.08 m 14 km
Staines AshRiver gauge, River Ash 0.10 m Very high ±0 56 km
Knowle GreenRiver gauge, River Ash 0.51 m Normal ±0 56 km

Nearby gauges

Gauge Level Compared with normal 24 hours Distance
Tumbling Bay WeirRiver gauge, Amwell Loop 30.41 m Normal +0.01 m 3.0 km
WadesmillRiver gauge, River Rib 0.19 m Normal ±0 4.3 km
Hoddesdon, Rye BridgeRiver gauge, River Lee 2.84 m Normal ±0 5.1 km
Roydon, Glen FabaRiver gauge, River Stort 1.43 m Normal ±0 5.6 km
Harlow, Elizabeth WayRiver gauge, Canons Brook 0.07 m Normal +0.02 m 5.8 km
Hertford, Hartham ParkRiver gauge, River Beane 0.21 m High +0.04 m 7.0 km
Harlow MillRiver gauge, River Stort 0.91 m Normal −0.01 m 8.1 km
Pishiobury BrookRiver gauge 0.93 m Low ±0 8.1 km

Questions and answers

Is the River Ash at Mardock higher than last year?

It is about the same as on this day last year, when the reading was 0.11 m.

What is a normal level for the River Ash at Mardock in mid-October?

The median for mid-October is 0.11 m. In 8 years out of 10 the reading falls between 0.09 m and 0.17 m, based on 21 years of records.

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 0.10 m on the gauge does not mean the water is that deep.

What is the water level of Mardock today?

On 19 Oct 2026, 05:00 BST, the water level was 0.10 m. Steady over the last 24 hours.

Is Mardock rising or falling?

Steady over the last 24 hours. Steady over the last 7 days.

Is the level of Mardock normal?

Normal for mid-October. Compared with 21 years of daily readings for this time of year.

What is the highest water level ever recorded at Mardock?

The highest level on record is 1.61 m on October 21, 2001. The lowest is 0.06 m on September 25, 1997.

For specialists

Station codes, datum, parameters, data quality and downloads
Operator
Environment Agency
Station code
ea:5080TH (Agency page)
Coordinates
51.81482, 0.02030 (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 0.10 m 2026-10-19 04:00 Provisional

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How to cite

Environment Agency: Mardock (ea:5080TH). Accessed October 19, 2026 via Nivelmap, https://nivelmap.com/en/united-kingdom/hertfordshire/mardock

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.