Chess at Bois Mill, Chesham
EA name: CHESS AT BOIS MILL, CHESHAM
Environment Agency sampling point TH-PCNR0014 · 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
- 3 Aug 2026, 10:0059 days ago · time as the Environment Agency records it (UK clock time; the source gives no time zone)
- Samples banked
- 23 since 4 Jun 2024 Imported periods: 1 Oct 2023 – 30 Sep 2026. Samples outside them are not shown here.
- Latest sample
- River / running surface water Environmental monitoring statutory (EU directives)
- Where
- National Grid 498391, 199374As published, to the nearest 1 m. Open in a map
- River, by its own name
- Chess
- River, by the map
- River ChessPlaced on the river its name gives, 1 m from the line.
- Next gauge downstream
- Rickmansworth On the River Chess · 12 km along the river
- Nearest gauge upstream
- Chesham On the River Chess · 3.4 km along the river
- Why it was sampled
- Environmental monitoring statutory (EU directives) (22 samples)
Monitoring (national agency policy) (1 samples)
Main measurements, river water
Dissolved oxygen
% saturation · code 9901 · %
82.1%
Sampled 3 Aug 2026, 59 days ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Aug 2026, 10:00 | 82.1 | 82.1% |
| 8 Jul 2026, 09:56 | 99.3 | 99.3% |
| 5 Jun 2026, 09:43 | 95.5 | 95.5% |
| 6 May 2026, 10:04 | 100.5 | 100.5% |
| 7 Apr 2026, 09:38 | 101.6 | 101.6% |
| 5 Mar 2026, 09:17 | 97.4 | 97.4% |
| 11 Feb 2026, 11:41 | 95.1 | 95.1% |
| 15 Jan 2026, 10:11 | 93.6 | 93.6% |
| 5 Dec 2025, 11:35 | 96.4 | 96.4% |
| 4 Nov 2025, 10:43 | 89.4 | 89.4% |
| 15 Oct 2025, 10:19 | 92.3 | 92.3% |
| 4 Apr 2025, 09:48 | 98.6 | 98.6% |
| 18 Mar 2025, 09:02 | 95.9 | 95.9% |
| 4 Feb 2025, 12:14 | 94.4 | 94.4% |
| 14 Jan 2025, 14:24 | 96.9 | 96.9% |
| 12 Dec 2024, 09:34 | 86.2 | 86.2% |
| 12 Nov 2024, 11:10 | 81.6 | 81.6% |
| 9 Oct 2024, 11:13 | 84.2 | 84.2% |
| 3 Sep 2024, 10:48 | 79.6 | 79.6% |
| 1 Aug 2024, 10:33 | 88.8 | 88.8% |
| 2 Jul 2024, 14:56 | 83.9 | 83.9% |
| 4 Jun 2024, 12:38 | 68.1 | 68.1% |
Dissolved oxygen
as O2 · code 9924 · mg/l
8.28 mg/l
Sampled 3 Aug 2026, 59 days ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Aug 2026, 10:00 | 8.28 | 8.28 mg/l |
| 8 Jul 2026, 09:56 | 9.49 | 9.49 mg/l |
| 5 Jun 2026, 09:43 | 9.84 | 9.84 mg/l |
| 6 May 2026, 10:04 | 10.9 | 10.9 mg/l |
| 7 Apr 2026, 09:38 | 11.8 | 11.8 mg/l |
| 5 Mar 2026, 09:17 | 11.3 | 11.3 mg/l |
| 11 Feb 2026, 11:41 | 10.5 | 10.5 mg/l |
| 15 Jan 2026, 10:11 | 10.7 | 10.7 mg/l |
| 5 Dec 2025, 11:35 | 11.5 | 11.5 mg/l |
| 4 Nov 2025, 10:43 | 9.53 | 9.53 mg/l |
| 15 Oct 2025, 10:19 | 9.7 | 9.7 mg/l |
| 4 Apr 2025, 09:48 | 10.8 | 10.8 mg/l |
| 18 Mar 2025, 09:02 | 11.6 | 11.6 mg/l |
| 4 Feb 2025, 12:14 | 10.8 | 10.8 mg/l |
| 14 Jan 2025, 14:24 | 11.1 | 11.1 mg/l |
| 12 Dec 2024, 09:34 | 9.78 | 9.78 mg/l |
| 12 Nov 2024, 11:10 | 9.09 | 9.09 mg/l |
| 9 Oct 2024, 11:13 | 8.62 | 8.62 mg/l |
| 3 Sep 2024, 10:48 | 7.9 | 7.9 mg/l |
| 1 Aug 2024, 10:33 | 8.82 | 8.82 mg/l |
| 2 Jul 2024, 14:56 | 8.53 | 8.53 mg/l |
| 4 Jun 2024, 12:38 | 7.02 | 7.02 mg/l |
Water temperature
code 0076 · °C
14.9 °C
Sampled 3 Aug 2026, 59 days ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Aug 2026, 10:00 | 14.9 | 14.9 °C |
| 8 Jul 2026, 09:56 | 17.4 | 17.4 °C |
| 5 Jun 2026, 09:43 | 13.9 | 13.9 °C |
| 6 May 2026, 10:04 | 11.8 | 11.8 °C |
| 7 Apr 2026, 09:38 | 8.8 | 8.8 °C |
| 5 Mar 2026, 09:17 | 8.8 | 8.8 °C |
| 11 Feb 2026, 11:41 | 10.7 | 10.7 °C |
| 15 Jan 2026, 10:11 | 9.4 | 9.4 °C |
| 5 Dec 2025, 11:35 | 7.7 | 7.7 °C |
| 4 Nov 2025, 10:43 | 12.4 | 12.4 °C |
| 15 Oct 2025, 10:19 | 13 | 13 °C |
| 4 Apr 2025, 09:48 | 11.1 | 11.1 °C |
| 18 Mar 2025, 09:02 | 7.1 | 7.1 °C |
| 4 Feb 2025, 12:14 | 9.4 | 9.4 °C |
| 14 Jan 2025, 14:24 | 9.2 | 9.2 °C |
| 12 Dec 2024, 09:34 | 9.7 | 9.7 °C |
| 12 Nov 2024, 11:10 | 10.5 | 10.5 °C |
| 9 Oct 2024, 11:13 | 14.2 | 14.2 °C |
| 3 Sep 2024, 10:48 | 15.6 | 15.6 °C |
| 1 Aug 2024, 10:33 | 15.6 | 15.6 °C |
| 2 Jul 2024, 14:56 | 14.5 | 14.5 °C |
| 4 Jun 2024, 12:38 | 13.9 | 13.9 °C |
pH
code 0061
7.98
Sampled 3 Aug 2026, 59 days ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Aug 2026, 10:00 | 7.98 | 7.98 |
| 8 Jul 2026, 09:56 | 7.65 | 7.65 |
| 5 Jun 2026, 09:43 | 7.74 | 7.74 |
| 6 May 2026, 10:04 | 7.73 | 7.73 |
| 7 Apr 2026, 09:38 | 7.99 | 7.99 |
| 5 Mar 2026, 09:17 | 8.22 | 8.22 |
| 11 Feb 2026, 11:41 | 7.69 | 7.69 |
| 15 Jan 2026, 10:11 | 8.07 | 8.07 |
| 5 Dec 2025, 11:35 | 7.88 | 7.88 |
| 4 Nov 2025, 10:43 | 7.86 | 7.86 |
| 15 Oct 2025, 10:19 | 7.69 | 7.69 |
| 4 Jul 2025, 10:31 | 7.76 | 7.76 |
| 4 Apr 2025, 09:48 | 7.65 | 7.65 |
| 18 Mar 2025, 09:02 | 8.02 | 8.02 |
| 4 Feb 2025, 12:14 | 7.73 | 7.73 |
| 14 Jan 2025, 14:24 | 7.73 | 7.73 |
| 12 Dec 2024, 09:34 | 7.7 | 7.7 |
| 12 Nov 2024, 11:10 | 7.65 | 7.65 |
| 9 Oct 2024, 11:13 | 7.57 | 7.57 |
| 3 Sep 2024, 10:48 | 7.52 | 7.52 |
| 1 Aug 2024, 10:33 | 7.65 | 7.65 |
| 2 Jul 2024, 14:56 | 7.6 | 7.6 |
Ammonia
ammoniacal nitrogen as N · code 0111 · mg/l
below 0.03 mg/l (not detected above this)
Sampled 3 Aug 2026, 59 days ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Aug 2026, 10:00 | <0.03 | below 0.03 mg/l (not detected above this) |
| 8 Jul 2026, 09:56 | <0.03 | below 0.03 mg/l (not detected above this) |
| 5 Jun 2026, 09:43 | 0.035 | 0.035 mg/l |
| 6 May 2026, 10:04 | 0.041 | 0.041 mg/l |
| 7 Apr 2026, 09:38 | 0.042 | 0.042 mg/l |
| 5 Mar 2026, 09:17 | <0.03 | below 0.03 mg/l (not detected above this) |
| 11 Feb 2026, 11:41 | 0.041 | 0.041 mg/l |
| 15 Jan 2026, 10:11 | <0.03 | below 0.03 mg/l (not detected above this) |
| 5 Dec 2025, 11:35 | 0.033 | 0.033 mg/l |
| 4 Nov 2025, 10:43 | <0.03 | below 0.03 mg/l (not detected above this) |
| 15 Oct 2025, 10:19 | 0.044 | 0.044 mg/l |
| 4 Apr 2025, 09:48 | 0.058 | 0.058 mg/l |
| 18 Mar 2025, 09:02 | <0.03 | below 0.03 mg/l (not detected above this) |
| 4 Feb 2025, 12:14 | 0.095 | 0.095 mg/l |
| 14 Jan 2025, 14:24 | 0.39 | 0.39 mg/l |
| 12 Dec 2024, 09:34 | 0.088 | 0.088 mg/l |
| 12 Nov 2024, 11:10 | 0.081 | 0.081 mg/l |
| 9 Oct 2024, 11:13 | 0.082 | 0.082 mg/l |
| 3 Sep 2024, 10:48 | 0.11 | 0.11 mg/l |
| 1 Aug 2024, 10:33 | 0.068 | 0.068 mg/l |
| 2 Jul 2024, 14:56 | 0.14 | 0.14 mg/l |
| 4 Jun 2024, 12:38 | 0.63 | 0.63 mg/l |
Nitrate
as nitrogen (N) · code 0117 · mg/l
4.38 mg/l
Sampled 3 Aug 2026, 59 days ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Aug 2026, 10:00 | 4.38 | 4.38 mg/l |
| 8 Jul 2026, 09:56 | 6.18 | 6.18 mg/l |
| 5 Jun 2026, 09:43 | 8.04 | 8.04 mg/l |
| 6 May 2026, 10:04 | 8.27 | 8.27 mg/l |
| 7 Apr 2026, 09:38 | 5.28 | 5.28 mg/l |
| 5 Mar 2026, 09:17 | 5.2 | 5.2 mg/l |
| 11 Feb 2026, 11:41 | 9.77 | 9.77 mg/l |
| 15 Jan 2026, 10:11 | 4.69 | 4.69 mg/l |
| 5 Dec 2025, 11:35 | 4.79 | 4.79 mg/l |
| 4 Nov 2025, 10:43 | 4.48 | 4.48 mg/l |
| 15 Oct 2025, 10:19 | 13.9 | 13.9 mg/l |
| 4 Apr 2025, 09:48 | 9.76 | 9.76 mg/l |
| 18 Mar 2025, 09:02 | 5.4 | 5.4 mg/l |
| 4 Feb 2025, 12:14 | 9.24 | 9.24 mg/l |
| 14 Jan 2025, 14:24 | 9.07 | 9.07 mg/l |
| 12 Dec 2024, 09:34 | 9.87 | 9.87 mg/l |
| 12 Nov 2024, 11:10 | 11 | 11 mg/l |
| 9 Oct 2024, 11:13 | 7.67 | 7.67 mg/l |
| 3 Sep 2024, 10:48 | 8.76 | 8.76 mg/l |
| 1 Aug 2024, 10:33 | 7.87 | 7.87 mg/l |
| 2 Jul 2024, 14:56 | 8.49 | 8.49 mg/l |
| 4 Jun 2024, 12:38 | 7.08 | 7.08 mg/l |
Phosphate
orthophosphate, reactive, as P · code 0180 · mg/l
0.075 mg/l
Sampled 3 Aug 2026, 59 days ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Aug 2026, 10:00 | 0.075 | 0.075 mg/l |
| 8 Jul 2026, 09:56 | 0.038 | 0.038 mg/l |
| 5 Jun 2026, 09:43 | 0.24 | 0.24 mg/l |
| 6 May 2026, 10:04 | 0.3 | 0.3 mg/l |
| 7 Apr 2026, 09:38 | 0.057 | 0.057 mg/l |
| 5 Mar 2026, 09:17 | 0.053 | 0.053 mg/l |
| 11 Feb 2026, 11:41 | 0.044 | 0.044 mg/l |
| 15 Jan 2026, 10:11 | 0.069 | 0.069 mg/l |
| 5 Dec 2025, 11:35 | 0.057 | 0.057 mg/l |
| 4 Nov 2025, 10:43 | 0.056 | 0.056 mg/l |
| 15 Oct 2025, 10:19 | 0.025 | 0.025 mg/l |
| 4 Apr 2025, 09:48 | 0.058 | 0.058 mg/l |
| 18 Mar 2025, 09:02 | 0.035 | 0.035 mg/l |
| 4 Feb 2025, 12:14 | 0.033 | 0.033 mg/l |
| 14 Jan 2025, 14:24 | 0.045 | 0.045 mg/l |
| 12 Dec 2024, 09:34 | 0.37 | 0.37 mg/l |
| 12 Nov 2024, 11:10 | 0.42 | 0.42 mg/l |
| 9 Oct 2024, 11:13 | 0.45 | 0.45 mg/l |
| 3 Sep 2024, 10:48 | 0.45 | 0.45 mg/l |
| 1 Aug 2024, 10:33 | 0.28 | 0.28 mg/l |
| 2 Jul 2024, 14:56 | 0.037 | 0.037 mg/l |
| 4 Jun 2024, 12:38 | 0.18 | 0.18 mg/l |
Conductivity
at 25 °C · code 0077 · µS/cm
651 µS/cm
Sampled 3 Aug 2026, 59 days ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Aug 2026, 10:00 | 651 | 651 µS/cm |
| 8 Jul 2026, 09:56 | 694 | 694 µS/cm |
| 5 Jun 2026, 09:43 | 665 | 665 µS/cm |
| 6 May 2026, 10:04 | 668 | 668 µS/cm |
| 7 Apr 2026, 09:38 | 627 | 627 µS/cm |
| 5 Mar 2026, 09:17 | 613 | 613 µS/cm |
| 11 Feb 2026, 11:41 | 653 | 653 µS/cm |
| 15 Jan 2026, 10:11 | 684 | 684 µS/cm |
| 5 Dec 2025, 11:35 | 611 | 611 µS/cm |
| 4 Nov 2025, 10:43 | 592 | 592 µS/cm |
| 15 Oct 2025, 10:19 | 748 | 748 µS/cm |
| 4 Apr 2025, 09:48 | 667 | 667 µS/cm |
| 18 Mar 2025, 09:02 | 572 | 572 µS/cm |
| 4 Feb 2025, 12:14 | 657 | 657 µS/cm |
| 14 Jan 2025, 14:24 | 676 | 676 µS/cm |
| 12 Dec 2024, 09:34 | 663 | 663 µS/cm |
| 12 Nov 2024, 11:10 | 694 | 694 µS/cm |
| 9 Oct 2024, 11:13 | 608 | 608 µS/cm |
| 3 Sep 2024, 10:48 | 683 | 683 µS/cm |
| 1 Aug 2024, 10:33 | 679 | 679 µS/cm |
| 2 Jul 2024, 14:56 | 668 | 668 µS/cm |
| 4 Jun 2024, 12:38 | 660 | 660 µS/cm |
Everything measured here
18 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 18 rows
| Determinand | Material | Results | First – last | Latest result |
|---|---|---|---|---|
| Oxygen, Dissolved, % Saturation 9901 | River water | 22 | Jun 2024 – Aug 2026 | 82.1% 3 Aug 2026 |
| Oxygen, Dissolved as O2 9924 | River water | 22 | Jun 2024 – Aug 2026 | 8.28 mg/l 3 Aug 2026 |
| Temperature of Water 0076 | River water | 22 | Jun 2024 – Aug 2026 | 14.9 °C 3 Aug 2026 |
| pH 0061 | River water | 22 | Jul 2024 – Aug 2026 | 7.98 3 Aug 2026 |
| Ammoniacal Nitrogen as N 0111 | River water | 22 | Jun 2024 – Aug 2026 | below 0.03 mg/l 3 Aug 2026 |
| Nitrate as N 0117 | River water | 22 | Jun 2024 – Aug 2026 | 4.38 mg/l 3 Aug 2026 |
| Orthophosphate, reactive as P 0180 | River water | 22 | Jun 2024 – Aug 2026 | 0.075 mg/l 3 Aug 2026 |
| Conductivity at 25 C 0077 | River water | 22 | Jun 2024 – Aug 2026 | 651 µS/cm 3 Aug 2026 |
| Alkalinity to pH 4.5 as CaCO3 0162 | River water | 22 | Jun 2024 – Aug 2026 | 260 mg/l 3 Aug 2026 |
| Ammonia un-ionised as N 0119 | River water | 21 | Jul 2024 – Aug 2026 | below 0.00075 mg/l 3 Aug 2026 |
| BOD : 5 Day ATU 0085 | River water | 22 | Jun 2024 – Aug 2026 | below 3 mg/l 3 Aug 2026 |
| Calcium, Dissolved 0239 | River water | 6 | Apr 2025 – Jul 2026 | 120 mg/l 8 Jul 2026 |
| Carbon, Organic, Dissolved as C :- {DOC} 0301 | River water | 6 | Apr 2025 – Jul 2026 | 1.7 mg/l 8 Jul 2026 |
| Iron 6051 | River water | 6 | Apr 2025 – Jul 2026 | below 30 µg/l 8 Jul 2026 |
| Iron, Dissolved 6460 | River water | 6 | Apr 2025 – Jul 2026 | 200 µg/l 8 Jul 2026 |
| Magnesium, Dissolved 0235 | River water | 6 | Apr 2025 – Jul 2026 | 2.5 mg/l 8 Jul 2026 |
| Nitrite as N 0118 | River water | 22 | Jun 2024 – Aug 2026 | 0.016 mg/l 3 Aug 2026 |
| Nitrogen, Total Oxidised as N 0116 | River water | 22 | Jun 2024 – Aug 2026 | 4.4 mg/l 3 Aug 2026 |
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.