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⤴Unusual rise — FloodRadar+Top 1% rise rate for this gauge.
Height for "Above a height"
Drag the line on the chart, or type a value:mASD
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You'll be notified when this gauge is rising more than 0.10 m/hr — a sign of rapidly increasing water levels.
You'll be notified when a new storm-overflow (sewage) discharge starts within ~3 km of this gauge, based on the water companies' near-real-time feeds.
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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
0.198 mASD
▬ Steady
24h Max
0.212 mASD
24h Min
0.181 mASD
Typical Range
0.17 - 1.40
mASD
Highest Recorded
2.10 mASD
EA official record
2.10 in our data (since Jan 1984)
Current level is 9% of this
🚽Sewage overflows nearby
Recent Water Levels
🌍 floodradar.co.uk
1 day
EA forecast (official)
Prediction V2
Prediction Eris
Nimbus beta
Experimental model fusing soil moisture, river flow, groundwater and catchment
character. The shaded band is its 10–90% range, widened so that about 80% of recent outcomes fall inside it.
Under evaluation — not yet promoted, so treat as a second opinion.
River Flow
90 days
Daily mean discharge (m³/s) with the daily min–max band, from the EA Hydrology API. Flow is the volume of water passing the gauge — often a more direct flood signal than level.
Flow Data: Daily mean flow (m³/s) to 6 Oct (2 days behind — the EA publishes each day's mean a day or two after it ends; unchecked, provisional)via EA Hydrology
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.
2 storm overflows are traced upstream of this gauge, the nearest 390 m away along the river. 0 report discharging now, 2 report not discharging.
Wessex Water · into Bitham Brook Via Sws · 5.9 km away in a straight line · its watercourse is not on the river map
0 spills · 0 hours in 2025
Not discharging now
16 other overflows within 6 km are downstream of this gauge or on another branch of the river network, so they are 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 →
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 Trowbridge flood history.
Flood areas linked to this gauge
Flood warnings and alerts are issued for whole areas. These are the 6 areas linked to this gauge, nearest first.
🌊 Mixed responseA balance of quick runoff and slower groundwater baseflow.
Your catchment is all the land that drains rainfall into the river above this gauge. Its character — how
steep, wet, wooded, urban or chalky that land is — decides how fast rain here turns into a rising river. A steep, bare or clay
catchment is “flashy” (rises and falls quickly, floods easily); a flat, chalk or well-wooded one is
slow and steady. The tiles below put numbers to that; the flow-duration curve reads left-to-right
from the river’s typical high flows (Q5) down to its low flows (Q95) — a steep curve means a flashy river.
The physical character of the land that drains to this gauge, and how it shapes its flood response — from the National River Flow Archive (UKCEH).
Baseflow Index
0.53
mixed response
Avg Annual Rainfall
810 mm/yr
1991–2020 · +4% since 1941–70
Urban Extent
5.7%
partly urbanised
Median Annual Flood
12.05 m³/s
QMED — typical yearly peak flow
Highest Daily Mean Flow
16.02 m³/s
3 Feb 1990 · daily mean, not the instantaneous peak
Flow-Duration Curve
Daily flow (m³/s) exceeded each % of the time — a steep curve is flashy, a flat one is steady. Q5 high · Q50 median · Q95 low.
Flat V weir for low flows and concrete rectangular rated section for high flows. Runoff figures suggest topographical and groundwater catchment areas do not coincide.
More detail
The catchment
Moderate relief catchment situated along Frome gap. Drains Chalk escarpment to the south-east with underlying geology of Jurassic clays. Predominant land use is arable farming, but contains towns of Trowbridge and Westbury. Runoff figures suggest topographical and groundwater catchment areas do not coincide. No major changes to catchment.
The station
Station is located in the centre of Trowbridge and was opened in 1984. Flat V weir (1:10) for low flows, then concrete rectangular rated section (high flows), 7.13m wide, set in deep culvert with vertical walls. Ultrasonic gauge installed 12/2006.
How it measures flow
Good approach, large downstream fall. Backing up from downstream due to debris. Rating for this station was reviewed in 2001. Previously two ratings existed for this station, the first was used from 1984 to 1992 based on theoretical rating for the weir. The second rating was fitted to the gaugings and used from 1992. Now one rating is applied across period of record; reviewed in 2011. A new top limb was derived using plot points from a time of flight ultrasonic installed at the site.
Flow regime
Moderate influences at low flows by abstractions & discharges.
The flow record
First few months to 11/03/1984 not included because of apparent datum change (higher levels in earlier record) and short gap. Full period of record peak flow data reviewed and released in September 2020 (WINFAP Files v9) and in August 2024 (WINFAP Files v13).
Timing, not cause. Gauges can move together simply because the same rain fell on both.
Frequently asked questions
Is the River Biss at Trowbridge flooding today?
The current level is 0.20m, which is within the typical range of 0.17 to 1.40m. Flooding is unlikely at this level.
Is the river level rising or falling at Trowbridge?
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 River Biss at Trowbridge?
The typical range at this station is 0.17m to 1.40m, based on Environment Agency historical data. Levels above 1.40m 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:
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Biss at Trowbridge (53029) View of weir from Upstream
Trowbridge weir viewed from upstream (Dec 2010)