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Water Level Rising Slightly
Up 0.02 m since 09:00, rising slightly
0.65

Grosmont Rhosllwyn River Station

Monnow
Wye (Hereford) catchment • Grosmont • Herefordshire County of • ID: NRW_H055004015 • Level
Natural Resources Wales does not publish a typical range for this gauge, so FloodRadar works one out from its own history (its usual daily lows and highs). It is not an official flood threshold.
(20m ago) • 4 readings/hr • 3 views

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Not an emergency service — if in danger call 999. Alerts rely on EA/SEPA/NRW data and are best-efforts. Terms

Current Level
0.654 m?
▲ Rising slightly
24h Max
0.655 m
24h Min
0.633 m
Typical Range
-2.51 - 1.65
m
Highest Recorded
4.84 m
14 Nov 2025
Since Feb 2024
Current level is 14% of this
🚽 Sewage overflows nearby

Recent Water Levels

🌍 floodradar.co.uk
1 day

Recent Readings

Steady over 5h
27 Oct 16:45 ▬ steady 0.654 m
27 Oct 16:30 ▬ steady 0.654 m
27 Oct 16:15 ▬ steady 0.654 m
27 Oct 16:00 ▬ steady 0.654 m
27 Oct 15:45 ▬ steady 0.654 m
27 Oct 15:30 ▼ -0.1 cm 0.654 m
27 Oct 15:15 ▲ +0.1 cm 0.655 m
27 Oct 15:00 ▬ steady 0.654 m
27 Oct 14:45 ▼ -0.1 cm 0.654 m
27 Oct 14:30 ▬ steady 0.655 m
27 Oct 14:15 ▬ steady 0.655 m
27 Oct 14:00 ▬ steady 0.655 m
27 Oct 13:45 ▬ steady 0.655 m
27 Oct 13:30 ▬ steady 0.655 m
27 Oct 13:15 ▬ steady 0.655 m
27 Oct 13:00 ▬ steady 0.655 m
27 Oct 12:45 ▲ +0.1 cm 0.655 m
27 Oct 12:30 ▬ steady 0.654 m
27 Oct 12:15 ▲ +0.1 cm 0.654 m
27 Oct 12:00 0.653 m

Station Details

  • Monitoring Station: Grosmont Rhosllwyn River Station
  • Watercourse: Monnow
  • Nearest Town: Grosmont
  • County: Herefordshire County of
  • Nearest reservoir: Grwyne Fawr (19.3 km) · 66.8% full (as of 9 Dec 2024)
  • Coordinates: 51°55'6"N 2°50'57"W (51.918400, -2.849200)
  • Open in: Google Maps · Apple Maps (opens your maps app)
  • Status: Active
  • Station Type: River level station (inferred)
Technical details: references, datum, range, flow archive
  • Station Reference: NRW_H055004015
  • NRW telemetry ID: H055004015 Water Level Stage
  • Parameter: Level
  • Unit: m?
  • Typical data delay: ~12 min (measured reading→publication lag)
  • Tidal: No
  • Lock / structure: No
  • Catchment Area: Wye (Hereford)
  • Typical Range: -2.506 – 1.648 m

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 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.

5 storm overflows are traced upstream of this gauge, the nearest 5.4 km away along the river. 0 report discharging now, 5 report not discharging.

💧
Dwr Cymru Welsh Water · into Dulas Brook · 5.4 km upstream along the river
37 spills · 553 hours in 2025
Not discharging now · last
💧
Dwr Cymru Welsh Water · into River Honddu · 13.4 km upstream along the river
Not discharging now · last
💧
Dwr Cymru Welsh Water · into Worm Brook · 19.2 km upstream along the river
Not discharging now · last
💧
Dwr Cymru Welsh Water · into Unnamed Brook · 19.5 km upstream along the river
Not discharging now · last
Placed on the river by its position alone.
💧
Dwr Cymru Welsh Water · into River Dore · 20.0 km upstream along the river
12 spills · 85 hours in 2025
Not discharging now · last

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. Sewage & storm overflows →

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 1.65 m on about 18 days. This year so far: 13 days.

2026 13 days, 2 of them high · 2 high so far
2025 14 days, 5 of them high · 5 high
2024 22 days, 4 of them high · 4 high

Counted from each day's highest reading. Days with missing or implausible readings are left out. The darker part is days above 2.90 m, the level this gauge tops only a few days a year.

Flood history near this gauge

Official Environment Agency warnings issued since 2012 for the 2 flood areas linked to this gauge (nearest 4.4 km away).

7flood warnings 57flood alerts

Most recent flood warning: 7 Feb 2026 — Dulas Brook at Ewyas Harold

Year by year
YearWarningsAlerts
2026 2 6
2025 2 4
2024 3 5
2023 0 1
2022 0 1
2021 0 2
2020 0 6
2019 0 5
2018 0 1
2016 0 6
2014 0 7
2013 0 5
2012 0 8

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 Grosmont flood history.

Flood areas linked to this gauge

Flood warnings and alerts are issued for whole areas. These are the 2 areas linked to this gauge, nearest first.

Frequently asked questions

Is the Monnow at Grosmont Rhosllwyn River Station flooding today?

The current level is 0.65m, which is within the typical range of -2.51 to 1.65m. Flooding is unlikely at this level.

Is the river level rising or falling at Grosmont Rhosllwyn River Station?

Based on the most recent readings, the level is currently rising slightly. 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 Monnow at Grosmont Rhosllwyn River Station?

The typical range at this station is -2.51m to 1.65m, based on Natural Resources Wales historical data. Levels above 1.65m are higher than usually seen and may indicate a flood risk.

How often is this river level data updated?

Readings are supplied by the Natural Resources Wales 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 →
Wales — NRW flood warnings

Wales: 0 severe flood warnings, 0 flood warnings and 5 flood alerts in force. Last successful check: 2026-10-27 17:03:02 UTC.

No current NRW warning or alert matched this gauge location.

Messages: Natural Resources Wales flood warnings API. Warning-area boundaries: Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved. Reused under the Open Government Licence v3.0. Boundaries from DataMapWales.

River readings supplied by Natural Resources Wales. FloodRadar checks for updates every 15 minutes; the reading timestamp shows the latest available observation.

The Environment Agency’s flood-zone map covers England. In Wales the Area map’s Flood Zones layer is Natural Resources Wales’s Flood Map for Planning, drawn by FloodRadar from its copy of NRW’s shapes where it holds them: an empty patch is not an absence of flood risk. Check NRW for official Welsh flood warnings and information.