Marazion River at Nancledra
EA name: MARAZION RIVER AT NANCLEDRA (also listed as “MARAZION RIVER AT NANCLEDRA ABOVE NANCLEDRA STW”)
Environment Agency sampling point SW-82110766 · 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
- 15 Dec 2025, 11:3310 months ago · time as the Environment Agency records it (UK clock time; the source gives no time zone). Not sampled since, as far as the archive shows: the Environment Agency was asked up to 30 Sep 2026 and had nothing newer.
- Samples banked
- 29 since 23 Oct 2023 Imported periods: 1 Oct 2023 – 30 Sep 2026. Samples outside them are not shown here.
- Latest sample
- River / running surface water Monitoring (national agency policy)
- Where
- National Grid 149588, 35951As published, to the nearest 1 m. Open in a map
- River, by its own name
- Marazion
- River, by the map
- Not placedTwo watercourses within reach (4 m and 32 m) and no name to choose by. The river map cannot say which watercourse this is.
- Next gauge downstream
- Not known
- Why it was sampled
- Monitoring (national agency policy) (29 samples)
Main measurements, river water
Dissolved oxygen
% saturation · code 9901 · %
98.4%
Sampled 15 Dec 2025, 10 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 15 Dec 2025, 11:33 | 98.4 | 98.4% |
| 1 Dec 2025, 12:39 | 98.6 | 98.6% |
| 17 Nov 2025, 13:14 | 99.1 | 99.1% |
| 4 Nov 2025, 13:54 | 97.9 | 97.9% |
| 11 Mar 2025, 11:14 | 99.4 | 99.4% |
| 25 Feb 2025, 12:16 | 100.9 | 100.9% |
| 20 Jan 2025, 12:38 | 99 | 99% |
| 4 Dec 2024, 11:41 | 99.4 | 99.4% |
| 18 Nov 2024, 14:12 | 98.9 | 98.9% |
| 17 Oct 2024, 13:32 | 100.1 | 100.1% |
| 23 Sep 2024, 13:50 | 93.9 | 93.9% |
| 22 Aug 2024, 13:10 | 103.5 | 103.5% |
| 16 Jul 2024, 10:15 | 101.5 | 101.5% |
| 17 Jun 2024, 13:32 | 101.1 | 101.1% |
| 16 May 2024, 17:43 | 100.8 | 100.8% |
| 22 Apr 2024, 11:03 | 103 | 103% |
| 19 Mar 2024, 13:15 | 100.5 | 100.5% |
| 22 Feb 2024, 12:44 | 99.1 | 99.1% |
| 15 Jan 2024, 13:48 | 101.5 | 101.5% |
| 7 Dec 2023, 11:32 | 99.6 | 99.6% |
| 20 Nov 2023, 13:13 | 99.4 | 99.4% |
| 23 Oct 2023, 15:00 | 98 | 98% |
Dissolved oxygen
as O2 · code 9924 · mg/l
11 mg/l
Sampled 15 Dec 2025, 10 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 15 Dec 2025, 11:33 | 11 | 11 mg/l |
| 1 Dec 2025, 12:39 | 10.8 | 10.8 mg/l |
| 17 Nov 2025, 13:14 | 11 | 11 mg/l |
| 4 Nov 2025, 13:54 | 10.3 | 10.3 mg/l |
| 11 Mar 2025, 11:14 | 11.1 | 11.1 mg/l |
| 25 Feb 2025, 12:16 | 11.3 | 11.3 mg/l |
| 20 Jan 2025, 12:38 | 11.5 | 11.5 mg/l |
| 4 Dec 2024, 11:41 | 11.1 | 11.1 mg/l |
| 18 Nov 2024, 14:12 | 10.8 | 10.8 mg/l |
| 17 Oct 2024, 13:32 | 10.4 | 10.4 mg/l |
| 23 Sep 2024, 13:50 | 9.57 | 9.57 mg/l |
| 22 Aug 2024, 13:10 | 10.3 | 10.3 mg/l |
| 16 Jul 2024, 10:15 | 10.4 | 10.4 mg/l |
| 17 Jun 2024, 13:32 | 10.7 | 10.7 mg/l |
| 16 May 2024, 17:43 | 10.3 | 10.3 mg/l |
| 22 Apr 2024, 11:03 | 11.3 | 11.3 mg/l |
| 19 Mar 2024, 13:15 | 10.8 | 10.8 mg/l |
| 22 Feb 2024, 12:44 | 11.2 | 11.2 mg/l |
| 15 Jan 2024, 13:48 | 11.8 | 11.8 mg/l |
| 7 Dec 2023, 11:32 | 11.1 | 11.1 mg/l |
| 20 Nov 2023, 13:13 | 10.7 | 10.7 mg/l |
| 23 Oct 2023, 15:00 | 10.4 | 10.4 mg/l |
Water temperature
code 0076 · °C
10.4 °C
Sampled 15 Dec 2025, 10 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 15 Dec 2025, 11:33 | 10.4 | 10.4 °C |
| 1 Dec 2025, 12:39 | 11.3 | 11.3 °C |
| 17 Nov 2025, 13:14 | 10.8 | 10.8 °C |
| 4 Nov 2025, 13:54 | 12.8 | 12.8 °C |
| 11 Mar 2025, 11:14 | 10.3 | 10.3 °C |
| 25 Feb 2025, 12:16 | 10.2 | 10.2 °C |
| 20 Jan 2025, 12:38 | 8.6 | 8.6 °C |
| 4 Dec 2024, 11:41 | 10.5 | 10.5 °C |
| 18 Nov 2024, 14:12 | 11.5 | 11.5 °C |
| 17 Oct 2024, 13:32 | 13.4 | 13.4 °C |
| 23 Sep 2024, 13:50 | 14.4 | 14.4 °C |
| 22 Aug 2024, 13:10 | 15.3 | 15.3 °C |
| 16 Jul 2024, 10:15 | 14 | 14 °C |
| 17 Jun 2024, 13:32 | 12.8 | 12.8 °C |
| 16 May 2024, 17:43 | 14.2 | 14.2 °C |
| 22 Apr 2024, 11:03 | 11.3 | 11.3 °C |
| 19 Mar 2024, 13:15 | 12 | 12 °C |
| 22 Feb 2024, 12:44 | 9.7 | 9.7 °C |
| 15 Jan 2024, 13:48 | 8.6 | 8.6 °C |
| 7 Dec 2023, 11:32 | 10.6 | 10.6 °C |
| 20 Nov 2023, 13:13 | 11.8 | 11.8 °C |
| 23 Oct 2023, 15:00 | 12.4 | 12.4 °C |
pH
code 0061
6.55
Sampled 15 Dec 2025, 10 months ago · 29 results banked
Every result (29)
| Sampled | Result as published | Reads as |
|---|---|---|
| 15 Dec 2025, 11:33 | 6.55 | 6.55 |
| 1 Dec 2025, 12:39 | 6.8 | 6.8 |
| 17 Nov 2025, 13:14 | 7.05 | 7.05 |
| 4 Nov 2025, 13:54 | 6.8 | 6.8 |
| 11 Mar 2025, 11:14 | 6.88 | 6.88 |
| 25 Feb 2025, 12:16 | 6.82 | 6.82 |
| 20 Jan 2025, 12:38 | 6.91 | 6.91 |
| 4 Dec 2024, 11:41 | 6.86 | 6.86 |
| 18 Nov 2024, 14:12 | 6.93 | 6.93 |
| 17 Oct 2024, 13:32 | 6.73 | 6.73 |
| 23 Sep 2024, 13:50 | 7.01 | 7.01 |
| 22 Aug 2024, 13:10 | 7.08 | 7.08 |
| 16 Jul 2024, 10:15 | 6.92 | 6.92 |
| 17 Jun 2024, 13:32 | 6.85 | 6.85 |
| 16 May 2024, 17:43 | 7.45 | 7.45 |
| 22 Apr 2024, 11:03 | 6.82 | 6.82 |
| 2 Apr 2024, 10:02 | 6.92 | 6.92 |
| 19 Mar 2024, 13:15 | 6.83 | 6.83 |
| 13 Mar 2024, 09:53 | 6.79 | 6.79 |
| 22 Feb 2024, 12:44 | 6.67 | 6.67 |
| 15 Feb 2024, 09:47 | 6.68 | 6.68 |
| 8 Feb 2024, 09:03 | 6.51 | 6.51 |
| 25 Jan 2024, 11:00 | 6.68 | 6.68 |
| 15 Jan 2024, 13:48 | 6.85 | 6.85 |
| 10 Jan 2024, 09:49 | 6.52 | 6.52 |
| 20 Dec 2023, 10:55 | 6.72 | 6.72 |
| 7 Dec 2023, 11:32 | 6.73 | 6.73 |
| 20 Nov 2023, 13:13 | 7.1 | 7.1 |
| 23 Oct 2023, 15:00 | 6.53 | 6.53 |
Ammonia
ammoniacal nitrogen as N · code 0111 · mg/l
below 0.03 mg/l (not detected above this)
Sampled 15 Dec 2025, 10 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 15 Dec 2025, 11:33 | <0.03 | below 0.03 mg/l (not detected above this) |
| 1 Dec 2025, 12:39 | <0.03 | below 0.03 mg/l (not detected above this) |
| 17 Nov 2025, 13:14 | <0.03 | below 0.03 mg/l (not detected above this) |
| 4 Nov 2025, 13:54 | <0.03 | below 0.03 mg/l (not detected above this) |
| 11 Mar 2025, 11:14 | <0.03 | below 0.03 mg/l (not detected above this) |
| 25 Feb 2025, 12:16 | <0.03 | below 0.03 mg/l (not detected above this) |
| 20 Jan 2025, 12:38 | <0.03 | below 0.03 mg/l (not detected above this) |
| 4 Dec 2024, 11:41 | <0.03 | below 0.03 mg/l (not detected above this) |
| 18 Nov 2024, 14:12 | <0.03 | below 0.03 mg/l (not detected above this) |
| 17 Oct 2024, 13:32 | <0.03 | below 0.03 mg/l (not detected above this) |
| 23 Sep 2024, 13:50 | <0.03 | below 0.03 mg/l (not detected above this) |
| 22 Aug 2024, 13:10 | <0.03 | below 0.03 mg/l (not detected above this) |
| 16 Jul 2024, 10:15 | <0.03 | below 0.03 mg/l (not detected above this) |
| 17 Jun 2024, 13:32 | <0.03 | below 0.03 mg/l (not detected above this) |
| 16 May 2024, 17:43 | <0.03 | below 0.03 mg/l (not detected above this) |
| 22 Apr 2024, 11:03 | <0.03 | below 0.03 mg/l (not detected above this) |
| 19 Mar 2024, 13:15 | <0.03 | below 0.03 mg/l (not detected above this) |
| 22 Feb 2024, 12:44 | <0.03 | below 0.03 mg/l (not detected above this) |
| 15 Jan 2024, 13:48 | <0.03 | below 0.03 mg/l (not detected above this) |
| 7 Dec 2023, 11:32 | <0.03 | below 0.03 mg/l (not detected above this) |
| 20 Nov 2023, 13:13 | <0.03 | below 0.03 mg/l (not detected above this) |
| 23 Oct 2023, 15:00 | <0.03 | below 0.03 mg/l (not detected above this) |
Nitrate
as nitrogen (N) · code 0117 · mg/l
1.1 mg/l
Sampled 15 Dec 2025, 10 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 15 Dec 2025, 11:33 | 1.1 | 1.1 mg/l |
| 1 Dec 2025, 12:39 | 0.946 | 0.946 mg/l |
| 17 Nov 2025, 13:14 | 1.8 | 1.8 mg/l |
| 4 Nov 2025, 13:54 | 0.626 | 0.626 mg/l |
| 11 Mar 2025, 11:14 | 1.8 | 1.8 mg/l |
| 25 Feb 2025, 12:16 | 1.9 | 1.9 mg/l |
| 20 Jan 2025, 12:38 | 2.1 | 2.1 mg/l |
| 4 Dec 2024, 11:41 | 2 | 2 mg/l |
| 18 Nov 2024, 14:12 | 1.6 | 1.6 mg/l |
| 17 Oct 2024, 13:32 | 1.5 | 1.5 mg/l |
| 23 Sep 2024, 13:50 | 1.3 | 1.3 mg/l |
| 22 Aug 2024, 13:10 | 1.6 | 1.6 mg/l |
| 16 Jul 2024, 10:15 | 1.59 | 1.59 mg/l |
| 17 Jun 2024, 13:32 | 1.7 | 1.7 mg/l |
| 16 May 2024, 17:43 | 1.7 | 1.7 mg/l |
| 22 Apr 2024, 11:03 | 1.8 | 1.8 mg/l |
| 19 Mar 2024, 13:15 | 1.8 | 1.8 mg/l |
| 22 Feb 2024, 12:44 | 1.5 | 1.5 mg/l |
| 15 Jan 2024, 13:48 | 2.1 | 2.1 mg/l |
| 7 Dec 2023, 11:32 | 1.1 | 1.1 mg/l |
| 20 Nov 2023, 13:13 | 2 | 2 mg/l |
| 23 Oct 2023, 15:00 | 1.4 | 1.4 mg/l |
Phosphate
orthophosphate, reactive, as P · code 0180 · mg/l
0.035 mg/l
Sampled 15 Dec 2025, 10 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 15 Dec 2025, 11:33 | 0.035 | 0.035 mg/l |
| 1 Dec 2025, 12:39 | 0.03 | 0.03 mg/l |
| 17 Nov 2025, 13:14 | <0.01 | below 0.01 mg/l (not detected above this) |
| 4 Nov 2025, 13:54 | 0.032 | 0.032 mg/l |
| 11 Mar 2025, 11:14 | <0.01 | below 0.01 mg/l (not detected above this) |
| 25 Feb 2025, 12:16 | <0.01 | below 0.01 mg/l (not detected above this) |
| 20 Jan 2025, 12:38 | <0.01 | below 0.01 mg/l (not detected above this) |
| 4 Dec 2024, 11:41 | <0.01 | below 0.01 mg/l (not detected above this) |
| 18 Nov 2024, 14:12 | 0.023 | 0.023 mg/l |
| 17 Oct 2024, 13:32 | <0.01 | below 0.01 mg/l (not detected above this) |
| 23 Sep 2024, 13:50 | <0.01 | below 0.01 mg/l (not detected above this) |
| 22 Aug 2024, 13:10 | 0.018 | 0.018 mg/l |
| 16 Jul 2024, 10:15 | <0.01 | below 0.01 mg/l (not detected above this) |
| 17 Jun 2024, 13:32 | <0.01 | below 0.01 mg/l (not detected above this) |
| 16 May 2024, 17:43 | <0.01 | below 0.01 mg/l (not detected above this) |
| 22 Apr 2024, 11:03 | <0.01 | below 0.01 mg/l (not detected above this) |
| 19 Mar 2024, 13:15 | <0.01 | below 0.01 mg/l (not detected above this) |
| 22 Feb 2024, 12:44 | 0.012 | 0.012 mg/l |
| 15 Jan 2024, 13:48 | <0.01 | below 0.01 mg/l (not detected above this) |
| 7 Dec 2023, 11:32 | 0.036 | 0.036 mg/l |
| 20 Nov 2023, 13:13 | <0.01 | below 0.01 mg/l (not detected above this) |
| 23 Oct 2023, 15:00 | 0.011 | 0.011 mg/l |
Conductivity
at 25 °C · code 0077 · µS/cm
113 µS/cm
Sampled 15 Dec 2025, 10 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 15 Dec 2025, 11:33 | 113 | 113 µS/cm |
| 1 Dec 2025, 12:39 | 121 | 121 µS/cm |
| 17 Nov 2025, 13:14 | 155 | 155 µS/cm |
| 4 Nov 2025, 13:54 | 132 | 132 µS/cm |
| 11 Mar 2025, 11:14 | 154 | 154 µS/cm |
| 25 Feb 2025, 12:16 | 152 | 152 µS/cm |
| 20 Jan 2025, 12:38 | 155 | 155 µS/cm |
| 4 Dec 2024, 11:41 | 154 | 154 µS/cm |
| 18 Nov 2024, 14:12 | 146 | 146 µS/cm |
| 17 Oct 2024, 13:32 | 145 | 145 µS/cm |
| 23 Sep 2024, 13:50 | 163 | 163 µS/cm |
| 22 Aug 2024, 13:10 | 161 | 161 µS/cm |
| 16 Jul 2024, 10:15 | 157 | 157 µS/cm |
| 17 Jun 2024, 13:32 | 155 | 155 µS/cm |
| 16 May 2024, 17:43 | 155 | 155 µS/cm |
| 22 Apr 2024, 11:03 | 152 | 152 µS/cm |
| 19 Mar 2024, 13:15 | 150 | 150 µS/cm |
| 22 Feb 2024, 12:44 | 125 | 125 µS/cm |
| 15 Jan 2024, 13:48 | 155 | 155 µS/cm |
| 7 Dec 2023, 11:32 | 120 | 120 µS/cm |
| 20 Nov 2023, 13:13 | 156 | 156 µS/cm |
| 23 Oct 2023, 15:00 | 157 | 157 µS/cm |
Everything measured here
24 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 24 rows
| Determinand | Material | Results | First – last | Latest result |
|---|---|---|---|---|
| Oxygen, Dissolved, % Saturation 9901 | River water | 22 | Oct 2023 – Dec 2025 | 98.4% 15 Dec 2025 |
| Oxygen, Dissolved as O2 9924 | River water | 22 | Oct 2023 – Dec 2025 | 11 mg/l 15 Dec 2025 |
| Temperature of Water 0076 | River water | 22 | Oct 2023 – Dec 2025 | 10.4 °C 15 Dec 2025 |
| pH 0061 | River water | 29 | Oct 2023 – Dec 2025 | 6.55 15 Dec 2025 |
| Ammoniacal Nitrogen as N 0111 | River water | 22 | Oct 2023 – Dec 2025 | below 0.03 mg/l 15 Dec 2025 |
| Nitrate as N 0117 | River water | 22 | Oct 2023 – Dec 2025 | 1.1 mg/l 15 Dec 2025 |
| Orthophosphate, reactive as P 0180 | River water | 22 | Oct 2023 – Dec 2025 | 0.035 mg/l 15 Dec 2025 |
| Conductivity at 25 C 0077 | River water | 22 | Oct 2023 – Dec 2025 | 113 µS/cm 15 Dec 2025 |
| Alkalinity to pH 4.5 as CaCO3 0162 | River water | 22 | Oct 2023 – Dec 2025 | 12 mg/l 15 Dec 2025 |
| Aluminium, Dissolved 6037 | River water | 7 | Dec 2023 – Apr 2024 | 130 µg/l 2 Apr 2024 |
| Ammonia un-ionised as N 0119 | River water | 22 | Oct 2023 – Dec 2025 | below 0.00002 mg/l 15 Dec 2025 |
| BOD : 5 Day ATU 0085 | River water | 17 | Feb 2024 – Dec 2025 | 1.4 mg/l 1 Dec 2025 |
| Cadmium, Dissolved 0106 | River water | 7 | Dec 2023 – Apr 2024 | 0.011 µg/l 2 Apr 2024 |
| Calcium, Dissolved 0239 | River water | 7 | Dec 2023 – Apr 2024 | 7 mg/l 2 Apr 2024 |
| Carbon, Organic, Dissolved as C :- {DOC} 0301 | River water | 7 | Dec 2023 – Apr 2024 | 3.5 mg/l 2 Apr 2024 |
| Chromium, Dissolved 3409 | River water | 7 | Dec 2023 – Apr 2024 | below 0.5 µg/l 2 Apr 2024 |
| Copper, Dissolved 6450 | River water | 7 | Dec 2023 – Apr 2024 | 2.7 µg/l 2 Apr 2024 |
| Lead, Dissolved 0052 | River water | 7 | Dec 2023 – Apr 2024 | 0.13 µg/l 2 Apr 2024 |
| Magnesium, Dissolved 0235 | River water | 7 | Dec 2023 – Apr 2024 | 2.4 mg/l 2 Apr 2024 |
| National Grid Reference : Whole : Field report 7434 | River water | 1 | Dec 2023 – Dec 2023 | 1 unitless value 20 Dec 2023 |
| Nickel, Dissolved 3410 | River water | 7 | Dec 2023 – Apr 2024 | below 0.5 µg/l 2 Apr 2024 |
| Nitrite as N 0118 | River water | 22 | Oct 2023 – Dec 2025 | below 0.004 mg/l 15 Dec 2025 |
| Nitrogen, Total Oxidised as N 0116 | River water | 22 | Oct 2023 – Dec 2025 | 1.1 mg/l 15 Dec 2025 |
| Zinc, Dissolved 3408 | River water | 7 | Dec 2023 – Apr 2024 | 3.5 µg/l 2 Apr 2024 |
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.