Grendon Brook Castle Ashby Arm downstream of Lock
EA name: GRENDON BK.CASTLE ASHBY ARM D/S LOCK
Environment Agency sampling point AN-CAAR100G · 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
- 4 Sep 2026, 11:1427 days ago · time as the Environment Agency records it (UK clock time; the source gives no time zone)
- Samples banked
- 28 since 3 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 487181, 260387As published, to the nearest 1 m. Open in a map
- River, by its own name
- Grendon Brook Castle Ashby Arm
- River, by the map
- An unnamed streamPlaced by position alone (the only river line close by), 3 m from the line.
- Next gauge downstream
- Islip Sluice On the River Nene · 31 km along the river (the path rests on a repair to the map)
- Why it was sampled
- Environmental monitoring statutory (EU directives) (28 samples)
4 visits found no water to sample (recorded as “No flow”).
Main measurements, river water
Dissolved oxygen
% saturation · code 9901 · %
56.1%
Sampled 3 Jul 2026, 3 months ago · 24 results banked
Every result (24)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Jul 2026, 11:27 | 56.1 | 56.1% |
| 5 Jun 2026, 10:37 | 92.7 | 92.7% |
| 22 May 2026, 09:38 | 80.5 | 80.5% |
| 10 Apr 2026, 10:35 | 105.3 | 105.3% |
| 3 Mar 2026, 12:30 | 99.7 | 99.7% |
| 13 Feb 2026, 10:56 | 95.6 | 95.6% |
| 15 Jan 2026, 12:33 | 96.9 | 96.9% |
| 5 Dec 2025, 11:18 | 105.4 | 105.4% |
| 7 Nov 2025, 15:13 | 72.2 | 72.2% |
| 7 Aug 2025, 11:02 | 53.9 | 53.9% |
| 2 Jul 2025, 10:28 | 29.3 | 29.3% |
| 4 Jun 2025, 11:11 | 86.7 | 86.7% |
| 14 May 2025, 12:40 | 79.4 | 79.4% |
| 30 Apr 2025, 11:50 | 81.5 | 81.5% |
| 4 Mar 2025, 10:46 | 95.9 | 95.9% |
| 7 Feb 2025, 11:57 | 100.6 | 100.6% |
| 14 Jan 2025, 11:14 | 96.2 | 96.2% |
| 3 Dec 2024, 11:53 | 93 | 93% |
| 1 Nov 2024, 12:49 | 90 | 90% |
| 15 Oct 2024, 11:11 | 88.2 | 88.2% |
| 2 Sep 2024, 12:08 | 59.2 | 59.2% |
| 2 Aug 2024, 12:15 | 48.3 | 48.3% |
| 1 Jul 2024, 11:54 | 79.5 | 79.5% |
| 3 Jun 2024, 11:05 | 88.2 | 88.2% |
Dissolved oxygen
as O2 · code 9924 · mg/l
5.43 mg/l
Sampled 3 Jul 2026, 3 months ago · 24 results banked
Every result (24)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Jul 2026, 11:27 | 5.43 | 5.43 mg/l |
| 5 Jun 2026, 10:37 | 8.95 | 8.95 mg/l |
| 22 May 2026, 09:38 | 7.79 | 7.79 mg/l |
| 10 Apr 2026, 10:35 | 11.3 | 11.3 mg/l |
| 3 Mar 2026, 12:30 | 11.2 | 11.2 mg/l |
| 13 Feb 2026, 10:56 | 11.6 | 11.6 mg/l |
| 15 Jan 2026, 12:33 | 12.2 | 12.2 mg/l |
| 5 Dec 2025, 11:18 | 13.4 | 13.4 mg/l |
| 7 Nov 2025, 15:13 | 7.54 | 7.54 mg/l |
| 7 Aug 2025, 11:02 | 5.13 | 5.13 mg/l |
| 2 Jul 2025, 10:28 | 2.76 | 2.76 mg/l |
| 4 Jun 2025, 11:11 | 8.48 | 8.48 mg/l |
| 14 May 2025, 12:40 | 7.32 | 7.32 mg/l |
| 30 Apr 2025, 11:50 | 7.63 | 7.63 mg/l |
| 4 Mar 2025, 10:46 | 11.9 | 11.9 mg/l |
| 7 Feb 2025, 11:57 | 13.2 | 13.2 mg/l |
| 14 Jan 2025, 11:14 | 12.7 | 12.7 mg/l |
| 3 Dec 2024, 11:53 | 11.1 | 11.1 mg/l |
| 1 Nov 2024, 12:49 | 9.77 | 9.77 mg/l |
| 15 Oct 2024, 11:11 | 9.82 | 9.82 mg/l |
| 2 Sep 2024, 12:08 | 5.44 | 5.44 mg/l |
| 2 Aug 2024, 12:15 | 4.16 | 4.16 mg/l |
| 1 Jul 2024, 11:54 | 7.34 | 7.34 mg/l |
| 3 Jun 2024, 11:05 | 8.35 | 8.35 mg/l |
Water temperature
code 0076 · °C
16.8 °C
Sampled 3 Jul 2026, 3 months ago · 24 results banked
Every result (24)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Jul 2026, 11:27 | 16.8 | 16.8 °C |
| 5 Jun 2026, 10:37 | 16.9 | 16.9 °C |
| 22 May 2026, 09:38 | 16.8 | 16.8 °C |
| 10 Apr 2026, 10:35 | 11.9 | 11.9 °C |
| 3 Mar 2026, 12:30 | 10 | 10 °C |
| 13 Feb 2026, 10:56 | 7.1 | 7.1 °C |
| 15 Jan 2026, 12:33 | 5.5 | 5.5 °C |
| 5 Dec 2025, 11:18 | 5.2 | 5.2 °C |
| 7 Nov 2025, 15:13 | 13.3 | 13.3 °C |
| 7 Aug 2025, 11:02 | 17.6 | 17.6 °C |
| 2 Jul 2025, 10:28 | 18.2 | 18.2 °C |
| 4 Jun 2025, 11:11 | 16.3 | 16.3 °C |
| 14 May 2025, 12:40 | 19.2 | 19.2 °C |
| 30 Apr 2025, 11:50 | 18.4 | 18.4 °C |
| 4 Mar 2025, 10:46 | 6 | 6 °C |
| 7 Feb 2025, 11:57 | 3.8 | 3.8 °C |
| 14 Jan 2025, 11:14 | 3.8 | 3.8 °C |
| 3 Dec 2024, 11:53 | 7.8 | 7.8 °C |
| 1 Nov 2024, 12:49 | 11.6 | 11.6 °C |
| 15 Oct 2024, 11:11 | 10.5 | 10.5 °C |
| 2 Sep 2024, 12:08 | 19.3 | 19.3 °C |
| 2 Aug 2024, 12:15 | 22.7 | 22.7 °C |
| 1 Jul 2024, 11:54 | 19.1 | 19.1 °C |
| 3 Jun 2024, 11:05 | 17.9 | 17.9 °C |
pH
code 0061
7.74
Sampled 3 Jul 2026, 3 months ago · 24 results banked
Every result (24)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Jul 2026, 11:27 | 7.74 | 7.74 |
| 5 Jun 2026, 10:37 | 8.25 | 8.25 |
| 22 May 2026, 09:38 | 7.99 | 7.99 |
| 10 Apr 2026, 10:35 | 8.63 | 8.63 |
| 3 Mar 2026, 12:30 | 8.2 | 8.2 |
| 13 Feb 2026, 10:56 | 8.15 | 8.15 |
| 15 Jan 2026, 12:33 | 8.12 | 8.12 |
| 5 Dec 2025, 11:18 | 8.72 | 8.72 |
| 7 Nov 2025, 15:13 | 8.06 | 8.06 |
| 7 Aug 2025, 11:02 | 8.67 | 8.67 |
| 2 Jul 2025, 10:28 | 7.65 | 7.65 |
| 4 Jun 2025, 11:11 | 8.29 | 8.29 |
| 14 May 2025, 12:40 | 7.84 | 7.84 |
| 30 Apr 2025, 11:50 | 7.75 | 7.75 |
| 4 Mar 2025, 10:46 | 8.23 | 8.23 |
| 7 Feb 2025, 11:57 | 8.27 | 8.27 |
| 14 Jan 2025, 11:14 | 8.07 | 8.07 |
| 3 Dec 2024, 11:53 | 8.19 | 8.19 |
| 1 Nov 2024, 12:49 | 7.99 | 7.99 |
| 15 Oct 2024, 11:11 | 7.87 | 7.87 |
| 2 Sep 2024, 12:08 | 7.95 | 7.95 |
| 2 Aug 2024, 12:15 | 7.61 | 7.61 |
| 1 Jul 2024, 11:54 | 8.16 | 8.16 |
| 3 Jun 2024, 11:05 | 8.1 | 8.1 |
Ammonia
ammoniacal nitrogen as N · code 0111 · mg/l
0.19 mg/l
Sampled 3 Jul 2026, 3 months ago · 24 results banked
Every result (24)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Jul 2026, 11:27 | 0.19 | 0.19 mg/l |
| 5 Jun 2026, 10:37 | <0.03 | below 0.03 mg/l (not detected above this) |
| 22 May 2026, 09:38 | 0.12 | 0.12 mg/l |
| 10 Apr 2026, 10:35 | 0.032 | 0.032 mg/l |
| 3 Mar 2026, 12:30 | 0.074 | 0.074 mg/l |
| 13 Feb 2026, 10:56 | 0.065 | 0.065 mg/l |
| 15 Jan 2026, 12:33 | 0.071 | 0.071 mg/l |
| 5 Dec 2025, 11:18 | 0.034 | 0.034 mg/l |
| 7 Nov 2025, 15:13 | 0.13 | 0.13 mg/l |
| 7 Aug 2025, 11:02 | 0.31 | 0.31 mg/l |
| 2 Jul 2025, 10:28 | 2.1 | 2.1 mg/l |
| 4 Jun 2025, 11:11 | <0.03 | below 0.03 mg/l (not detected above this) |
| 14 May 2025, 12:40 | 0.05 | 0.05 mg/l |
| 30 Apr 2025, 11:50 | 0.34 | 0.34 mg/l |
| 4 Mar 2025, 10:46 | 0.056 | 0.056 mg/l |
| 7 Feb 2025, 11:57 | 0.043 | 0.043 mg/l |
| 14 Jan 2025, 11:14 | 0.062 | 0.062 mg/l |
| 3 Dec 2024, 11:53 | 0.066 | 0.066 mg/l |
| 1 Nov 2024, 12:49 | 0.042 | 0.042 mg/l |
| 15 Oct 2024, 11:11 | 0.14 | 0.14 mg/l |
| 2 Sep 2024, 12:08 | <0.03 | below 0.03 mg/l (not detected above this) |
| 2 Aug 2024, 12:15 | 0.32 | 0.32 mg/l |
| 1 Jul 2024, 11:54 | <0.03 | below 0.03 mg/l (not detected above this) |
| 3 Jun 2024, 11:05 | 0.12 | 0.12 mg/l |
Nitrate
as nitrogen (N) · code 0117 · mg/l
0.462 mg/l
Sampled 3 Jul 2026, 3 months ago · 24 results banked
Every result (24)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Jul 2026, 11:27 | 0.462 | 0.462 mg/l |
| 5 Jun 2026, 10:37 | <0.196 | below 0.196 mg/l (not detected above this) |
| 22 May 2026, 09:38 | 0.689 | 0.689 mg/l |
| 10 Apr 2026, 10:35 | 2.77 | 2.77 mg/l |
| 3 Mar 2026, 12:30 | 8.46 | 8.46 mg/l |
| 13 Feb 2026, 10:56 | 11 | 11 mg/l |
| 15 Jan 2026, 12:33 | 11 | 11 mg/l |
| 5 Dec 2025, 11:18 | 4.88 | 4.88 mg/l |
| 7 Nov 2025, 15:13 | 0.191 | 0.191 mg/l |
| 7 Aug 2025, 11:02 | 0.17 | 0.17 mg/l |
| 2 Jul 2025, 10:28 | 0.205 | 0.205 mg/l |
| 4 Jun 2025, 11:11 | <0.196 | below 0.196 mg/l (not detected above this) |
| 14 May 2025, 12:40 | 0.424 | 0.424 mg/l |
| 30 Apr 2025, 11:50 | 1.07 | 1.07 mg/l |
| 4 Mar 2025, 10:46 | 6.38 | 6.38 mg/l |
| 7 Feb 2025, 11:57 | 8.58 | 8.58 mg/l |
| 14 Jan 2025, 11:14 | 8.18 | 8.18 mg/l |
| 3 Dec 2024, 11:53 | 7.65 | 7.65 mg/l |
| 1 Nov 2024, 12:49 | 4.32 | 4.32 mg/l |
| 15 Oct 2024, 11:11 | 6.62 | 6.62 mg/l |
| 2 Sep 2024, 12:08 | 0.193 | 0.193 mg/l |
| 2 Aug 2024, 12:15 | 0.332 | 0.332 mg/l |
| 1 Jul 2024, 11:54 | 0.19 | 0.19 mg/l |
| 3 Jun 2024, 11:05 | 0.453 | 0.453 mg/l |
Phosphate
orthophosphate, reactive, as P · code 0180 · mg/l
0.23 mg/l
Sampled 3 Jul 2026, 3 months ago · 23 results banked
Every result (23)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Jul 2026, 11:27 | 0.23 | 0.23 mg/l |
| 5 Jun 2026, 10:37 | 0.044 | 0.044 mg/l |
| 22 May 2026, 09:38 | 0.044 | 0.044 mg/l |
| 10 Apr 2026, 10:35 | 0.01 | 0.01 mg/l |
| 3 Mar 2026, 12:30 | 0.013 | 0.013 mg/l |
| 13 Feb 2026, 10:56 | 0.023 | 0.023 mg/l |
| 15 Jan 2026, 12:33 | 0.018 | 0.018 mg/l |
| 5 Dec 2025, 11:18 | <0.01 | below 0.01 mg/l (not detected above this) |
| 7 Nov 2025, 15:13 | 0.036 | 0.036 mg/l |
| 7 Aug 2025, 11:02 | 0.38 | 0.38 mg/l |
| 2 Jul 2025, 10:28 | 0.5 | 0.5 mg/l |
| 4 Jun 2025, 11:11 | 0.064 | 0.064 mg/l |
| 14 May 2025, 12:40 | 0.055 | 0.055 mg/l |
| 30 Apr 2025, 11:50 | 0.023 | 0.023 mg/l |
| 4 Mar 2025, 10:46 | 0.019 | 0.019 mg/l |
| 7 Feb 2025, 11:57 | 0.037 | 0.037 mg/l |
| 14 Jan 2025, 11:14 | 0.049 | 0.049 mg/l |
| 1 Nov 2024, 12:49 | <0.01 | below 0.01 mg/l (not detected above this) |
| 15 Oct 2024, 11:11 | 0.018 | 0.018 mg/l |
| 2 Sep 2024, 12:08 | 0.18 | 0.18 mg/l |
| 2 Aug 2024, 12:15 | 0.13 | 0.13 mg/l |
| 1 Jul 2024, 11:54 | 0.064 | 0.064 mg/l |
| 3 Jun 2024, 11:05 | 0.014 | 0.014 mg/l |
Conductivity
at 25 °C · code 0077 · µS/cm
523 µS/cm
Sampled 3 Jul 2026, 3 months ago · 24 results banked
Every result (24)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Jul 2026, 11:27 | 523 | 523 µS/cm |
| 5 Jun 2026, 10:37 | 562 | 562 µS/cm |
| 22 May 2026, 09:38 | 613 | 613 µS/cm |
| 10 Apr 2026, 10:35 | 600 | 600 µS/cm |
| 3 Mar 2026, 12:30 | 693 | 693 µS/cm |
| 13 Feb 2026, 10:56 | 697 | 697 µS/cm |
| 15 Jan 2026, 12:33 | 716 | 716 µS/cm |
| 5 Dec 2025, 11:18 | 639 | 639 µS/cm |
| 7 Nov 2025, 15:13 | 537 | 537 µS/cm |
| 7 Aug 2025, 11:02 | 463 | 463 µS/cm |
| 2 Jul 2025, 10:28 | 493 | 493 µS/cm |
| 4 Jun 2025, 11:11 | 573 | 573 µS/cm |
| 14 May 2025, 12:40 | 578 | 578 µS/cm |
| 30 Apr 2025, 11:50 | 582 | 582 µS/cm |
| 4 Mar 2025, 10:46 | 724 | 724 µS/cm |
| 7 Feb 2025, 11:57 | 754 | 754 µS/cm |
| 14 Jan 2025, 11:14 | 734 | 734 µS/cm |
| 3 Dec 2024, 11:53 | 701 | 701 µS/cm |
| 1 Nov 2024, 12:49 | 716 | 716 µS/cm |
| 15 Oct 2024, 11:11 | 702 | 702 µS/cm |
| 2 Sep 2024, 12:08 | 438 | 438 µS/cm |
| 2 Aug 2024, 12:15 | 359 | 359 µS/cm |
| 1 Jul 2024, 11:54 | 535 | 535 µS/cm |
| 3 Jun 2024, 11:05 | 531 | 531 µS/cm |
Everything measured here
13 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 13 rows
| Determinand | Material | Results | First – last | Latest result |
|---|---|---|---|---|
| Oxygen, Dissolved, % Saturation 9901 | River water | 24 | Jun 2024 – Jul 2026 | 56.1% 3 Jul 2026 |
| Oxygen, Dissolved as O2 9924 | River water | 24 | Jun 2024 – Jul 2026 | 5.43 mg/l 3 Jul 2026 |
| Temperature of Water 0076 | River water | 24 | Jun 2024 – Jul 2026 | 16.8 °C 3 Jul 2026 |
| pH 0061 | River water | 24 | Jun 2024 – Jul 2026 | 7.74 3 Jul 2026 |
| Ammoniacal Nitrogen as N 0111 | River water | 24 | Jun 2024 – Jul 2026 | 0.19 mg/l 3 Jul 2026 |
| Nitrate as N 0117 | River water | 24 | Jun 2024 – Jul 2026 | 0.462 mg/l 3 Jul 2026 |
| Orthophosphate, reactive as P 0180 | River water | 23 | Jun 2024 – Jul 2026 | 0.23 mg/l 3 Jul 2026 |
| Conductivity at 25 C 0077 | River water | 24 | Jun 2024 – Jul 2026 | 523 µS/cm 3 Jul 2026 |
| Alkalinity to pH 4.5 as CaCO3 0162 | River water | 23 | Jun 2024 – Jul 2026 | 180 mg/l 3 Jul 2026 |
| Ammonia un-ionised as N 0119 | River water | 24 | Jun 2024 – Jul 2026 | 0.00317 mg/l 3 Jul 2026 |
| Nitrite as N 0118 | River water | 24 | Jun 2024 – Jul 2026 | 0.038 mg/l 3 Jul 2026 |
| Nitrogen, Total Oxidised as N 0116 | River water | 24 | Jun 2024 – Jul 2026 | 0.5 mg/l 3 Jul 2026 |
| No flow /No sample 7668 | River water | 4 | Sep 2025 – Sep 2026 | No flow/discharge at sampling point 4 Sep 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.