Live levels from 3 monitoring stations across Surrey, updated every 15 minutes.
| Station | Level now | Status | ||
|---|---|---|---|---|
| Trumps Green | 0.76 mASD 29m ago | Normal | ||
| 5.6 km by river | ||||
| Guildford Street | 0.50 mASD 29m ago | Normal | ||
| 540 m by river | ||||
| Free Prae Road | 1.10 mASD 29m ago | Normal | ||
Stations are listed from source to mouth as the water flows, traced on the river map (OS Open Rivers) and the Environment Agency’s own links between its gauges. A distance “by river” is along the river, and is shown only where the map traces the path.
Contains OS data © Crown copyright and database rights 2026.
Streams and rivers with a gauge whose water joins Chertsey Bourne above one of its gauges, from the source down. The river map knows where gauges are, not every stream, so a tributary without a gauge is not listed here.
No gauged tributary joins Chertsey Bourne above Free Prae Road on the river map. Streams without a gauge are not counted here.
Below Free Prae Road, its water next reaches Shepperton Lock, a gauge on River Thames, 4.1 km by river downstream.
Tributaries and where they join are traced on the river map (OS Open Rivers, edition 2026-04) and the Environment Agency’s links between its gauges. The map holds distances between gauges, not the junctions themselves, so a junction is placed between two gauges, and no further up than the tributary’s own lowest gauge. Contains OS data © Crown copyright and database rights 2026.
1 storm overflow is traced upstream of Free Prae Road, Chertsey Bourne’s lowest gauge on the river map: on Chertsey Bourne itself, on its gauged tributaries, and on smaller streams that join above there.
Official figures for 2025, for the overflow traced upstream of Free Prae Road: 27 spills over 472 hours.
Each overflow is listed in the stretch above the first gauge its water reaches, from the source down, as on the Gauges tab. A stretch of Chertsey Bourne includes the smaller streams that join it there.
A status is the water company’s own monitor: it says whether an overflow is discharging, never how much or why, and a spill does not by itself explain a change in a river level. A status older than two hours is shown as unknown. Annual figures are the official returns: 12/24-hour spills for England and Wales, overflow events for Scotland (Scottish Water counts differently, so the two cannot be compared). “No data” means the monitor produced no usable data that year, not zero. Overflows are placed on OS Open Rivers (edition 2026-04), which leaves out many small channels: an overflow the map cannot place may still drain here. Contains OS data © Crown copyright and database rights 2026. Sewage in Britain’s rivers →
Live status: © Thames Water storm overflow activity data, licensed under CC BY 4.0. Annual figures for England: Environment Agency Event Duration Monitoring return, © Environment Agency copyright and/or database right, Open Government Licence v3.0.
Dated samples taken by the Environment Agency, not live readings. Results are published days to months after the sample is taken, and many points are sampled only a few times a year, or have not been sampled for years.
12 sampling points on the Chertsey Bourne and the streams that join it above Free Prae Road, and below it. 5 have a sample from the last 12 months; 7 have any sample banked. Listed from the source down, grouped by the next gauge each one's water reaches.
| Sampling point | Watercourse (map) | Above the gauge | Last sample | Latest results (river water) |
|---|---|---|---|---|
| Upstream of Bodens Ride, Bracknell Forest | unnamed stream | 12 km | 30 Sep 2026 · 8 days ago | Oxygen 42.5% Jun 2026Temp 13.6 °C Jun 2026pH 4.78 Jun 2026Ammonia 0.12 mg/l Jun 2026 |
| Chertsey Bourne at Buckhurst Road | unnamed stream | 7.0 km | 23 Jul 2026 · 3 months ago | Oxygen 83.5%Temp 19.2 °CpH 7.46Ammonia below 0.03 mg/l |
| Riverside Walk Nature Reserve | The Bourne | 1.1 km | 5 Dec 2025 · 10 months ago | Oxygen 92.7%Temp 5.9 °CpH 7.49Ammonia 0.17 mg/l |
| Sampling point | Watercourse (map) | Above the gauge | Last sample | Latest results (river water) |
|---|---|---|---|---|
| Mead Lake Ditch | Mead Lake Ditch | 4.3 km | Last sampled 4 Oct 2021, before the imported period | |
| Mead Lake Ditch, upstream of Intersection | Mead Lake Ditch | 4.3 km | 13 Mar 2024 · 2.6 years ago | Oxygen 55.4%Temp 10.1 °CpH 7.31Ammonia 0.26 mg/l |
| Mead Lake Ditch N of Green Lane | Mead Lake Ditch | 4.3 km | Last sampled 26 Nov 2019, before the imported period | |
| Bourne (North) at Thorpegreen Bridge | The Bourne | 3.5 km | 18 Aug 2026 · 51 days ago | Oxygen 69%Temp 18.7 °CpH 7.17Ammonia 0.23 mg/l |
| The Moat at Green Road Footbr | The Moat | 3.5 km | Last sampled 26 Nov 2019, before the imported period | |
| Mead Lake Ditch at Norlands Lane | Mead Lake Ditch | 3.5 km | Last sampled 26 Nov 2019, before the imported period | |
| Mead Lake Ditch, downstream of Intersection | Mead Lake Ditch | 3.4 km | 13 Mar 2024 · 2.6 years ago | Oxygen 80.5%Temp 9.6 °CpH 7.45Ammonia 0.51 mg/l |
| Bourne (North) at Hamperstone Bridge | The Bourne | 0.8 km | 17 Jul 2026 · 3 months ago | Oxygen 67.7%Temp 22.1 °CpH 7.52Ammonia 0.14 mg/l |
| Sampling point | Watercourse (map) | Below the gauge | Last sample | Latest results (river water) |
|---|---|---|---|---|
| Bourne above Thames | The Bourne | 2.9 km | Last sampled 14 Jan 2020, before the imported period |
Distances are along the river to the gauge named. England's samples only.
FloodRadar does not grade these results: there is no overall score, and official river classifications are a separate dataset. A sample taken downstream of an overflow does not by itself show where anything in it came from. River connections and distances are traced on OS Open Rivers (edition 2026-04), which leaves out many small channels.
Water samples: Environment Agency Water Quality Archive, © Environment Agency and/or database right 2026, Open Government Licence v3.0.
Contains OS data © Crown copyright and database rights 2026.
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