River Colne downstream of Chalkney Mill
EA name: RSN2457 R.COLNE D/S CHALKNEY MILL
Environment Agency sampling point AN-RSN2457 · Freshwater - rivers · listed as open (“open” does not mean it is sampled now)
These are samples taken on a date, not live readings of the river. Results reach the Environment Agency's archive days to months after the sample is taken, so the newest here may be weeks or months old. FloodRadar does not grade them.
Where and when
- Last sampled
- 2 Oct 2026, 09:1922 days ago · time as the Environment Agency records it (UK clock time; the source gives no time zone)
- Samples banked
- 19 since 2 Jan 2025 Imported periods: 1 Oct 2023 – 24 Oct 2026. Samples outside them are not shown here.
- Latest sample
- River / running surface water Monitoring (national agency policy) · results completed 6 Oct 2026
- Where
- National Grid 587595, 228434As published, to the nearest 1 m. Open in a map
- River, by its own name
- Colne
- River, by the map
- River ColnePlaced on the river its name gives, 32 m from the line.
- Next gauge downstream
- Lexden On the River Colne · 13 km along the river
- Nearest gauge upstream
- Earls Colne On the River Colne · 3.3 km along the riverEARLS COLNE FGS 3.3 km along the river
- Why it was sampled
- Monitoring (national agency policy) (19 samples)
Results here were completed a median of 4 days after the sample was taken (2 to 8 days, 11 samples).
Main measurements, river water
Dissolved oxygen
% saturation · code 9901 · %
77.5%
Sampled 2 Oct 2026, 22 days ago · 19 results banked
Every result (19)
| Sampled | Result as published | Reads as |
|---|---|---|
| 2 Oct 2026, 09:19 | 77.5 | 77.5% |
| 17 Sep 2026, 11:55 | 79.9 | 79.9% |
| 10 Aug 2026, 14:49 | 106.4 | 106.4% |
| 13 Jul 2026, 14:08 | 120.2 | 120.2% |
| 19 Jun 2026, 08:47 | 75.1 | 75.1% |
| 28 May 2026, 09:17 | 71.9 | 71.9% |
| 15 Apr 2026, 12:09 | 101.8 | 101.8% |
| 3 Dec 2025, 10:06 | 88.8 | 88.8% |
| 11 Nov 2025, 11:33 | 65.4 | 65.4% |
| 16 Oct 2025, 11:40 | 81.6 | 81.6% |
| 23 Sep 2025, 10:27 | 80.9 | 80.9% |
| 4 Aug 2025, 11:03 | 95.1 | 95.1% |
| 17 Jul 2025, 12:55 | 91.4 | 91.4% |
| 26 Jun 2025, 15:04 | 95.3 | 95.3% |
| 12 May 2025, 10:46 | 77.2 | 77.2% |
| 24 Apr 2025, 07:32 | 85.4 | 85.4% |
| 31 Mar 2025, 08:29 | 90.9 | 90.9% |
| 10 Feb 2025, 10:58 | 98.2 | 98.2% |
| 2 Jan 2025, 09:47 | 94.3 | 94.3% |
Dissolved oxygen
as O2 · code 9924 · mg/l
8.09 mg/l
Sampled 2 Oct 2026, 22 days ago · 19 results banked
Every result (19)
| Sampled | Result as published | Reads as |
|---|---|---|
| 2 Oct 2026, 09:19 | 8.09 | 8.09 mg/l |
| 17 Sep 2026, 11:55 | 7.83 | 7.83 mg/l |
| 10 Aug 2026, 14:49 | 9.69 | 9.69 mg/l |
| 13 Jul 2026, 14:08 | 10.4 | 10.4 mg/l |
| 19 Jun 2026, 08:47 | 7.01 | 7.01 mg/l |
| 28 May 2026, 09:17 | 6.76 | 6.76 mg/l |
| 15 Apr 2026, 12:09 | 10.9 | 10.9 mg/l |
| 3 Dec 2025, 10:06 | 10.7 | 10.7 mg/l |
| 11 Nov 2025, 11:33 | 7.17 | 7.17 mg/l |
| 16 Oct 2025, 11:40 | 8.65 | 8.65 mg/l |
| 23 Sep 2025, 10:27 | 8.67 | 8.67 mg/l |
| 4 Aug 2025, 11:03 | 9.01 | 9.01 mg/l |
| 17 Jul 2025, 12:55 | 8.52 | 8.52 mg/l |
| 26 Jun 2025, 15:04 | 8.58 | 8.58 mg/l |
| 12 May 2025, 10:46 | 7.77 | 7.77 mg/l |
| 24 Apr 2025, 07:32 | 9.28 | 9.28 mg/l |
| 31 Mar 2025, 08:29 | 10.3 | 10.3 mg/l |
| 10 Feb 2025, 10:58 | 12.5 | 12.5 mg/l |
| 2 Jan 2025, 09:47 | 11.5 | 11.5 mg/l |
Water temperature
code 0076 · °C
13.3 °C
Sampled 2 Oct 2026, 22 days ago · 19 results banked
Every result (19)
| Sampled | Result as published | Reads as |
|---|---|---|
| 2 Oct 2026, 09:19 | 13.3 | 13.3 °C |
| 17 Sep 2026, 11:55 | 16.2 | 16.2 °C |
| 10 Aug 2026, 14:49 | 19.8 | 19.8 °C |
| 13 Jul 2026, 14:08 | 22.3 | 22.3 °C |
| 19 Jun 2026, 08:47 | 18.6 | 18.6 °C |
| 28 May 2026, 09:17 | 18.2 | 18.2 °C |
| 15 Apr 2026, 12:09 | 12 | 12 °C |
| 3 Dec 2025, 10:06 | 7.3 | 7.3 °C |
| 11 Nov 2025, 11:33 | 11.1 | 11.1 °C |
| 16 Oct 2025, 11:40 | 12.6 | 12.6 °C |
| 23 Sep 2025, 10:27 | 12.1 | 12.1 °C |
| 4 Aug 2025, 11:03 | 17.8 | 17.8 °C |
| 17 Jul 2025, 12:55 | 18.6 | 18.6 °C |
| 26 Jun 2025, 15:04 | 20.3 | 20.3 °C |
| 12 May 2025, 10:46 | 14.9 | 14.9 °C |
| 24 Apr 2025, 07:32 | 11.5 | 11.5 °C |
| 31 Mar 2025, 08:29 | 9.6 | 9.6 °C |
| 10 Feb 2025, 10:58 | 5.1 | 5.1 °C |
| 2 Jan 2025, 09:47 | 6.6 | 6.6 °C |
pH
code 0061
7.82
Sampled 2 Oct 2026, 22 days ago · 19 results banked
Every result (19)
| Sampled | Result as published | Reads as |
|---|---|---|
| 2 Oct 2026, 09:19 | 7.82 | 7.82 |
| 17 Sep 2026, 11:55 | 8.03 | 8.03 |
| 10 Aug 2026, 14:49 | 8.07 | 8.07 |
| 13 Jul 2026, 14:08 | 8.21 | 8.21 |
| 19 Jun 2026, 08:47 | 7.86 | 7.86 |
| 28 May 2026, 09:17 | 7.85 | 7.85 |
| 15 Apr 2026, 12:09 | 8.24 | 8.24 |
| 3 Dec 2025, 10:06 | 7.88 | 7.88 |
| 11 Nov 2025, 11:33 | 7.63 | 7.63 |
| 16 Oct 2025, 11:40 | 7.72 | 7.72 |
| 23 Sep 2025, 10:27 | 7.88 | 7.88 |
| 4 Aug 2025, 11:03 | 7.92 | 7.92 |
| 17 Jul 2025, 12:55 | 7.82 | 7.82 |
| 26 Jun 2025, 15:04 | 7.98 | 7.98 |
| 12 May 2025, 10:46 | 7.74 | 7.74 |
| 24 Apr 2025, 07:32 | 8.13 | 8.13 |
| 31 Mar 2025, 08:29 | 8.25 | 8.25 |
| 10 Feb 2025, 10:58 | 8.11 | 8.11 |
| 2 Jan 2025, 09:47 | 8.01 | 8.01 |
Ammonia
ammoniacal nitrogen as N · code 0111 · mg/l
below 0.03 mg/l (not detected above this)
Sampled 2 Oct 2026, 22 days ago · 19 results banked
Every result (19)
| Sampled | Result as published | Reads as |
|---|---|---|
| 2 Oct 2026, 09:19 | <0.03 | below 0.03 mg/l (not detected above this) |
| 17 Sep 2026, 11:55 | 0.035 | 0.035 mg/l |
| 10 Aug 2026, 14:49 | <0.03 | below 0.03 mg/l (not detected above this) |
| 13 Jul 2026, 14:08 | <0.03 | below 0.03 mg/l (not detected above this) |
| 19 Jun 2026, 08:47 | 0.036 | 0.036 mg/l |
| 28 May 2026, 09:17 | 0.096 | 0.096 mg/l |
| 15 Apr 2026, 12:09 | 0.068 | 0.068 mg/l |
| 3 Dec 2025, 10:06 | 0.16 | 0.16 mg/l |
| 11 Nov 2025, 11:33 | 0.36 | 0.36 mg/l |
| 16 Oct 2025, 11:40 | 0.061 | 0.061 mg/l |
| 23 Sep 2025, 10:27 | 0.043 | 0.043 mg/l |
| 4 Aug 2025, 11:03 | 0.037 | 0.037 mg/l |
| 17 Jul 2025, 12:55 | 0.068 | 0.068 mg/l |
| 26 Jun 2025, 15:04 | 0.045 | 0.045 mg/l |
| 12 May 2025, 10:46 | 0.19 | 0.19 mg/l |
| 24 Apr 2025, 07:32 | 0.085 | 0.085 mg/l |
| 31 Mar 2025, 08:29 | 0.31 | 0.31 mg/l |
| 10 Feb 2025, 10:58 | 0.083 | 0.083 mg/l |
| 2 Jan 2025, 09:47 | 0.14 | 0.14 mg/l |
Nitrate
as nitrogen (N) · code 0117 · mg/l
7.48 mg/l
Sampled 2 Oct 2026, 22 days ago · 19 results banked
Every result (19)
| Sampled | Result as published | Reads as |
|---|---|---|
| 2 Oct 2026, 09:19 | 7.48 | 7.48 mg/l |
| 17 Sep 2026, 11:55 | 6.35 | 6.35 mg/l |
| 10 Aug 2026, 14:49 | 7.78 | 7.78 mg/l |
| 13 Jul 2026, 14:08 | 5.98 | 5.98 mg/l |
| 19 Jun 2026, 08:47 | 5.67 | 5.67 mg/l |
| 28 May 2026, 09:17 | 6.32 | 6.32 mg/l |
| 15 Apr 2026, 12:09 | 6.64 | 6.64 mg/l |
| 3 Dec 2025, 10:06 | 8.95 | 8.95 mg/l |
| 11 Nov 2025, 11:33 | 7.41 | 7.41 mg/l |
| 16 Oct 2025, 11:40 | 9.92 | 9.92 mg/l |
| 23 Sep 2025, 10:27 | 9.34 | 9.34 mg/l |
| 4 Aug 2025, 11:03 | 9.94 | 9.94 mg/l |
| 17 Jul 2025, 12:55 | 8.29 | 8.29 mg/l |
| 26 Jun 2025, 15:04 | 6.84 | 6.84 mg/l |
| 12 May 2025, 10:46 | 8.36 | 8.36 mg/l |
| 24 Apr 2025, 07:32 | 6.63 | 6.63 mg/l |
| 31 Mar 2025, 08:29 | 8.6 | 8.6 mg/l |
| 10 Feb 2025, 10:58 | 8.86 | 8.86 mg/l |
| 2 Jan 2025, 09:47 | 7.55 | 7.55 mg/l |
Phosphate
orthophosphate, reactive, as P · code 0180 · mg/l
0.16 mg/l
Sampled 2 Oct 2026, 22 days ago · 19 results banked
Every result (19)
| Sampled | Result as published | Reads as |
|---|---|---|
| 2 Oct 2026, 09:19 | 0.16 | 0.16 mg/l |
| 17 Sep 2026, 11:55 | 0.15 | 0.15 mg/l |
| 10 Aug 2026, 14:49 | 0.16 | 0.16 mg/l |
| 13 Jul 2026, 14:08 | 0.2 | 0.2 mg/l |
| 19 Jun 2026, 08:47 | 0.17 | 0.17 mg/l |
| 28 May 2026, 09:17 | 0.21 | 0.21 mg/l |
| 15 Apr 2026, 12:09 | 0.18 | 0.18 mg/l |
| 3 Dec 2025, 10:06 | 0.1 | 0.1 mg/l |
| 11 Nov 2025, 11:33 | 0.14 | 0.14 mg/l |
| 16 Oct 2025, 11:40 | 0.17 | 0.17 mg/l |
| 23 Sep 2025, 10:27 | 0.14 | 0.14 mg/l |
| 4 Aug 2025, 11:03 | 0.19 | 0.19 mg/l |
| 17 Jul 2025, 12:55 | 0.17 | 0.17 mg/l |
| 26 Jun 2025, 15:04 | 0.18 | 0.18 mg/l |
| 12 May 2025, 10:46 | 0.1 | 0.1 mg/l |
| 24 Apr 2025, 07:32 | 0.092 | 0.092 mg/l |
| 31 Mar 2025, 08:29 | 0.077 | 0.077 mg/l |
| 10 Feb 2025, 10:58 | 0.089 | 0.089 mg/l |
| 2 Jan 2025, 09:47 | 0.14 | 0.14 mg/l |
Conductivity
at 25 °C · code 0077 · µS/cm
960 µS/cm
Sampled 2 Oct 2026, 22 days ago · 19 results banked
Every result (19)
| Sampled | Result as published | Reads as |
|---|---|---|
| 2 Oct 2026, 09:19 | 960 | 960 µS/cm |
| 17 Sep 2026, 11:55 | 918 | 918 µS/cm |
| 10 Aug 2026, 14:49 | 1000 | 1000 µS/cm |
| 13 Jul 2026, 14:08 | 977 | 977 µS/cm |
| 19 Jun 2026, 08:47 | 855 | 855 µS/cm |
| 28 May 2026, 09:17 | 919 | 919 µS/cm |
| 15 Apr 2026, 12:09 | 830 | 830 µS/cm |
| 3 Dec 2025, 10:06 | 889 | 889 µS/cm |
| 11 Nov 2025, 11:33 | 918 | 918 µS/cm |
| 16 Oct 2025, 11:40 | 951 | 951 µS/cm |
| 23 Sep 2025, 10:27 | 955 | 955 µS/cm |
| 4 Aug 2025, 11:03 | 899 | 899 µS/cm |
| 17 Jul 2025, 12:55 | 964 | 964 µS/cm |
| 26 Jun 2025, 15:04 | 965 | 965 µS/cm |
| 12 May 2025, 10:46 | 896 | 896 µS/cm |
| 24 Apr 2025, 07:32 | 830 | 830 µS/cm |
| 31 Mar 2025, 08:29 | 993 | 993 µS/cm |
| 10 Feb 2025, 10:58 | 792 | 792 µS/cm |
| 2 Jan 2025, 09:47 | 744 | 744 µS/cm |
Everything measured here
19 determinands, each kept by its code, unit and sample material: results in different units or on different materials are never mixed. A “below” result is under the laboratory's detection limit, not zero.
Show all 19 rows
| Determinand | Material | Results | First – last | Latest result |
|---|---|---|---|---|
| Oxygen, Dissolved, % Saturation 9901 | River water | 19 | Jan 2025 – Oct 2026 | 77.5% 2 Oct 2026 |
| Oxygen, Dissolved as O2 9924 | River water | 19 | Jan 2025 – Oct 2026 | 8.09 mg/l 2 Oct 2026 |
| Temperature of Water 0076 | River water | 19 | Jan 2025 – Oct 2026 | 13.3 °C 2 Oct 2026 |
| pH 0061 | River water | 19 | Jan 2025 – Oct 2026 | 7.82 2 Oct 2026 |
| Ammoniacal Nitrogen as N 0111 | River water | 19 | Jan 2025 – Oct 2026 | below 0.03 mg/l 2 Oct 2026 |
| Nitrate as N 0117 | River water | 19 | Jan 2025 – Oct 2026 | 7.48 mg/l 2 Oct 2026 |
| Orthophosphate, reactive as P 0180 | River water | 19 | Jan 2025 – Oct 2026 | 0.16 mg/l 2 Oct 2026 |
| Conductivity at 25 C 0077 | River water | 19 | Jan 2025 – Oct 2026 | 960 µS/cm 2 Oct 2026 |
| Alkalinity to pH 4.5 as CaCO3 0162 | River water | 19 | Jan 2025 – Oct 2026 | 220 mg/l 2 Oct 2026 |
| Ammonia un-ionised as N 0119 | River water | 19 | Jan 2025 – Oct 2026 | below 0.00046 mg/l 2 Oct 2026 |
| Carbon, Organic, Dissolved as C :- {DOC} 0301 | River water | 12 | Jan 2025 – Dec 2025 | 4.8 mg/l 3 Dec 2025 |
| Chloride 0172 | River water | 12 | Jan 2025 – Dec 2025 | 82 mg/l 3 Dec 2025 |
| Flow Type 2896 | River water | 11 | Jan 2025 – Nov 2025 | Moderate Flow 11 Nov 2025 |
| Nitrite as N 0118 | River water | 19 | Jan 2025 – Oct 2026 | 0.02 mg/l 2 Oct 2026 |
| Nitrogen, Total as N 9686 | River water | 12 | Jan 2025 – Dec 2025 | 9.5 mg/l 3 Dec 2025 |
| Nitrogen, Total Oxidised as N 0116 | River water | 19 | Jan 2025 – Oct 2026 | 7.5 mg/l 2 Oct 2026 |
| Phosphorus, Total as P 0348 | River water | 12 | Jan 2025 – Dec 2025 | 0.12 mg/l 3 Dec 2025 |
| Silica, reactive as SiO2 0182 | River water | 12 | Jan 2025 – Dec 2025 | 12 mg/l 3 Dec 2025 |
| Solids, Suspended at 105 C 0135 | River water | 1 | Dec 2025 – Dec 2025 | 5.2 mg/l 3 Dec 2025 |
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.