Tributary of Mevagissey Stream at Heligan Mill
EA name: TRIB MEVAGISSEY STREAM AT HELIGAN MILL (also listed as “TRIB OF MEVAGISSEY STREAM AT HELIGAN MILL”)
Environment Agency sampling point SW-81810620 · 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
- 19 Mar 2026, 11:516 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
- 20 since 18 Jul 2024 Imported periods: 1 Oct 2023 – 30 Sep 2026. Samples outside them are not shown here.
- Latest sample
- River / running surface water Planned investigation (local monitoring)
- Where
- National Grid 200330, 45919As published, to the nearest 1 m. Open in a map
- River, by its own name
- Mevagissey Stream
- River, by the map
- Not placedTwo watercourses within reach (4 m and 73 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
- Planned investigation (local monitoring) (20 samples)
Main measurements, river water
Dissolved oxygen
% saturation · code 9901 · %
99%
Sampled 19 Mar 2026, 6 months ago · 18 results banked
Every result (18)
| Sampled | Result as published | Reads as |
|---|---|---|
| 19 Mar 2026, 11:51 | 99 | 99% |
| 12 Feb 2026, 10:10 | 98.1 | 98.1% |
| 16 Jan 2026, 09:21 | 98 | 98% |
| 2 Dec 2025, 09:52 | 95.7 | 95.7% |
| 14 Nov 2025, 13:08 | 97.6 | 97.6% |
| 21 Oct 2025, 12:21 | 93.6 | 93.6% |
| 9 Sep 2025, 14:43 | 93.3 | 93.3% |
| 15 Apr 2025, 13:45 | 97.6 | 97.6% |
| 7 Apr 2025, 13:40 | 97.1 | 97.1% |
| 13 Mar 2025, 12:14 | 99.4 | 99.4% |
| 25 Feb 2025, 11:17 | 98.8 | 98.8% |
| 16 Jan 2025, 09:00 | 98.4 | 98.4% |
| 10 Dec 2024, 13:19 | 100 | 100% |
| 13 Nov 2024, 10:06 | 96.8 | 96.8% |
| 29 Oct 2024, 11:57 | 97.3 | 97.3% |
| 25 Sep 2024, 10:31 | 97 | 97% |
| 14 Aug 2024, 11:12 | 95.5 | 95.5% |
| 18 Jul 2024, 12:05 | 96.1 | 96.1% |
Dissolved oxygen
as O2 · code 9924 · mg/l
10.9 mg/l
Sampled 19 Mar 2026, 6 months ago · 18 results banked
Every result (18)
| Sampled | Result as published | Reads as |
|---|---|---|
| 19 Mar 2026, 11:51 | 10.9 | 10.9 mg/l |
| 12 Feb 2026, 10:10 | 10.9 | 10.9 mg/l |
| 16 Jan 2026, 09:21 | 11.5 | 11.5 mg/l |
| 2 Dec 2025, 09:52 | 10.9 | 10.9 mg/l |
| 14 Nov 2025, 13:08 | 10.1 | 10.1 mg/l |
| 21 Oct 2025, 12:21 | 9.84 | 9.84 mg/l |
| 9 Sep 2025, 14:43 | 9.47 | 9.47 mg/l |
| 15 Apr 2025, 13:45 | 11 | 11 mg/l |
| 7 Apr 2025, 13:40 | 10.3 | 10.3 mg/l |
| 13 Mar 2025, 12:14 | 11.6 | 11.6 mg/l |
| 25 Feb 2025, 11:17 | 11.1 | 11.1 mg/l |
| 16 Jan 2025, 09:00 | 11.4 | 11.4 mg/l |
| 10 Dec 2024, 13:19 | 11.6 | 11.6 mg/l |
| 13 Nov 2024, 10:06 | 10.9 | 10.9 mg/l |
| 29 Oct 2024, 11:57 | 10.3 | 10.3 mg/l |
| 25 Sep 2024, 10:31 | 10 | 10 mg/l |
| 14 Aug 2024, 11:12 | 9.38 | 9.38 mg/l |
| 18 Jul 2024, 12:05 | 9.42 | 9.42 mg/l |
Water temperature
code 0076 · °C
11.1 °C
Sampled 19 Mar 2026, 6 months ago · 18 results banked
Every result (18)
| Sampled | Result as published | Reads as |
|---|---|---|
| 19 Mar 2026, 11:51 | 11.1 | 11.1 °C |
| 12 Feb 2026, 10:10 | 10.4 | 10.4 °C |
| 16 Jan 2026, 09:21 | 8.3 | 8.3 °C |
| 2 Dec 2025, 09:52 | 9.5 | 9.5 °C |
| 14 Nov 2025, 13:08 | 13.5 | 13.5 °C |
| 21 Oct 2025, 12:21 | 13 | 13 °C |
| 9 Sep 2025, 14:43 | 14.6 | 14.6 °C |
| 15 Apr 2025, 13:45 | 10 | 10 °C |
| 7 Apr 2025, 13:40 | 12.6 | 12.6 °C |
| 13 Mar 2025, 12:14 | 8.5 | 8.5 °C |
| 25 Feb 2025, 11:17 | 10.1 | 10.1 °C |
| 16 Jan 2025, 09:00 | 8.8 | 8.8 °C |
| 10 Dec 2024, 13:19 | 8.7 | 8.7 °C |
| 13 Nov 2024, 10:06 | 10 | 10 °C |
| 29 Oct 2024, 11:57 | 12.8 | 12.8 °C |
| 25 Sep 2024, 10:31 | 13.8 | 13.8 °C |
| 14 Aug 2024, 11:12 | 16.1 | 16.1 °C |
| 18 Jul 2024, 12:05 | 16.2 | 16.2 °C |
pH
code 0061
7.65
Sampled 19 Mar 2026, 6 months ago · 18 results banked
Every result (18)
| Sampled | Result as published | Reads as |
|---|---|---|
| 19 Mar 2026, 11:51 | 7.65 | 7.65 |
| 12 Feb 2026, 10:10 | 7.39 | 7.39 |
| 16 Jan 2026, 09:21 | 7.67 | 7.67 |
| 2 Dec 2025, 09:52 | 7.36 | 7.36 |
| 14 Nov 2025, 13:08 | 7.32 | 7.32 |
| 21 Oct 2025, 12:21 | 7.79 | 7.79 |
| 9 Sep 2025, 14:43 | 7.74 | 7.74 |
| 15 Apr 2025, 13:45 | 7.54 | 7.54 |
| 7 Apr 2025, 13:40 | 7.72 | 7.72 |
| 13 Mar 2025, 12:14 | 7.62 | 7.62 |
| 25 Feb 2025, 11:17 | 7.22 | 7.22 |
| 16 Jan 2025, 09:00 | 7.53 | 7.53 |
| 10 Dec 2024, 13:19 | 7.4 | 7.4 |
| 13 Nov 2024, 10:06 | 7.52 | 7.52 |
| 29 Oct 2024, 11:57 | 7.51 | 7.51 |
| 25 Sep 2024, 10:31 | 7.52 | 7.52 |
| 14 Aug 2024, 11:12 | 7.88 | 7.88 |
| 18 Jul 2024, 12:05 | 7.6 | 7.6 |
Ammonia
ammoniacal nitrogen as N · code 0111 · mg/l
below 0.03 mg/l (not detected above this)
Sampled 19 Mar 2026, 6 months ago · 18 results banked
Every result (18)
| Sampled | Result as published | Reads as |
|---|---|---|
| 19 Mar 2026, 11:51 | <0.03 | below 0.03 mg/l (not detected above this) |
| 12 Feb 2026, 10:10 | <0.03 | below 0.03 mg/l (not detected above this) |
| 16 Jan 2026, 09:21 | <0.03 | below 0.03 mg/l (not detected above this) |
| 2 Dec 2025, 09:52 | 0.03 | 0.03 mg/l |
| 14 Nov 2025, 13:08 | <0.03 | below 0.03 mg/l (not detected above this) |
| 21 Oct 2025, 12:21 | <0.03 | below 0.03 mg/l (not detected above this) |
| 9 Sep 2025, 14:43 | <0.03 | below 0.03 mg/l (not detected above this) |
| 15 Apr 2025, 13:45 | <0.03 | below 0.03 mg/l (not detected above this) |
| 7 Apr 2025, 13:40 | <0.03 | below 0.03 mg/l (not detected above this) |
| 13 Mar 2025, 12:14 | <0.03 | below 0.03 mg/l (not detected above this) |
| 25 Feb 2025, 11:17 | <0.03 | below 0.03 mg/l (not detected above this) |
| 16 Jan 2025, 09:00 | <0.03 | below 0.03 mg/l (not detected above this) |
| 10 Dec 2024, 13:19 | <0.03 | below 0.03 mg/l (not detected above this) |
| 13 Nov 2024, 10:06 | <0.03 | below 0.03 mg/l (not detected above this) |
| 29 Oct 2024, 11:57 | <0.03 | below 0.03 mg/l (not detected above this) |
| 25 Sep 2024, 10:31 | <0.03 | below 0.03 mg/l (not detected above this) |
| 14 Aug 2024, 11:12 | <0.03 | below 0.03 mg/l (not detected above this) |
| 18 Jul 2024, 12:05 | <0.03 | below 0.03 mg/l (not detected above this) |
Nitrate
as nitrogen (N) · code 0117 · mg/l
1.8 mg/l
Sampled 19 Mar 2026, 6 months ago · 18 results banked
Every result (18)
| Sampled | Result as published | Reads as |
|---|---|---|
| 19 Mar 2026, 11:51 | 1.8 | 1.8 mg/l |
| 12 Feb 2026, 10:10 | 2 | 2 mg/l |
| 16 Jan 2026, 09:21 | 2 | 2 mg/l |
| 2 Dec 2025, 09:52 | 1.9 | 1.9 mg/l |
| 14 Nov 2025, 13:08 | 1.6 | 1.6 mg/l |
| 21 Oct 2025, 12:21 | 0.856 | 0.856 mg/l |
| 9 Sep 2025, 14:43 | 1.09 | 1.09 mg/l |
| 15 Apr 2025, 13:45 | 0.946 | 0.946 mg/l |
| 7 Apr 2025, 13:40 | 0.916 | 0.916 mg/l |
| 13 Mar 2025, 12:14 | 1.7 | 1.7 mg/l |
| 25 Feb 2025, 11:17 | 2 | 2 mg/l |
| 16 Jan 2025, 09:00 | 2 | 2 mg/l |
| 10 Dec 2024, 13:19 | 1.8 | 1.8 mg/l |
| 13 Nov 2024, 10:06 | 1.29 | 1.29 mg/l |
| 29 Oct 2024, 11:57 | 1.4 | 1.4 mg/l |
| 25 Sep 2024, 10:31 | 0.756 | 0.756 mg/l |
| 14 Aug 2024, 11:12 | 0.886 | 0.886 mg/l |
| 18 Jul 2024, 12:05 | 1.09 | 1.09 mg/l |
Phosphate
orthophosphate, reactive, as P · code 0180 · mg/l
0.011 mg/l
Sampled 19 Mar 2026, 6 months ago · 18 results banked
Every result (18)
| Sampled | Result as published | Reads as |
|---|---|---|
| 19 Mar 2026, 11:51 | 0.011 | 0.011 mg/l |
| 12 Feb 2026, 10:10 | 0.017 | 0.017 mg/l |
| 16 Jan 2026, 09:21 | 0.019 | 0.019 mg/l |
| 2 Dec 2025, 09:52 | 0.027 | 0.027 mg/l |
| 14 Nov 2025, 13:08 | 0.03 | 0.03 mg/l |
| 21 Oct 2025, 12:21 | 0.011 | 0.011 mg/l |
| 9 Sep 2025, 14:43 | 0.024 | 0.024 mg/l |
| 15 Apr 2025, 13:45 | 0.017 | 0.017 mg/l |
| 7 Apr 2025, 13:40 | <0.01 | below 0.01 mg/l (not detected above this) |
| 13 Mar 2025, 12:14 | 0.013 | 0.013 mg/l |
| 25 Feb 2025, 11:17 | 0.016 | 0.016 mg/l |
| 16 Jan 2025, 09:00 | 0.017 | 0.017 mg/l |
| 10 Dec 2024, 13:19 | 0.01 | 0.01 mg/l |
| 13 Nov 2024, 10:06 | 0.014 | 0.014 mg/l |
| 29 Oct 2024, 11:57 | 0.01 | 0.01 mg/l |
| 25 Sep 2024, 10:31 | 0.03 | 0.03 mg/l |
| 14 Aug 2024, 11:12 | 0.013 | 0.013 mg/l |
| 18 Jul 2024, 12:05 | 0.017 | 0.017 mg/l |
Conductivity
at 25 °C · code 0077 · µS/cm
251 µS/cm
Sampled 19 Mar 2026, 6 months ago · 18 results banked
Every result (18)
| Sampled | Result as published | Reads as |
|---|---|---|
| 19 Mar 2026, 11:51 | 251 | 251 µS/cm |
| 12 Feb 2026, 10:10 | 243 | 243 µS/cm |
| 16 Jan 2026, 09:21 | 242 | 242 µS/cm |
| 2 Dec 2025, 09:52 | 223 | 223 µS/cm |
| 14 Nov 2025, 13:08 | 213 | 213 µS/cm |
| 21 Oct 2025, 12:21 | 266 | 266 µS/cm |
| 9 Sep 2025, 14:43 | 259 | 259 µS/cm |
| 15 Apr 2025, 13:45 | 232 | 232 µS/cm |
| 7 Apr 2025, 13:40 | 263 | 263 µS/cm |
| 13 Mar 2025, 12:14 | 258 | 258 µS/cm |
| 25 Feb 2025, 11:17 | 238 | 238 µS/cm |
| 16 Jan 2025, 09:00 | 244 | 244 µS/cm |
| 10 Dec 2024, 13:19 | 249 | 249 µS/cm |
| 13 Nov 2024, 10:06 | 260 | 260 µS/cm |
| 29 Oct 2024, 11:57 | 246 | 246 µS/cm |
| 25 Sep 2024, 10:31 | 247 | 247 µS/cm |
| 14 Aug 2024, 11:12 | 310 | 310 µS/cm |
| 18 Jul 2024, 12:05 | 249 | 249 µS/cm |
E. coli
confirmed, membrane filtration · code 2348 · per 100 ml
500 per 100 ml
Sampled 29 Jan 2025, 20 months ago · 2 results banked
Every result (2)
| Sampled | Result as published | Reads as |
|---|---|---|
| 29 Jan 2025, 13:57 | 500 | 500 per 100 ml |
| 29 Jan 2025, 11:28 | 860 | 860 per 100 ml |
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 | 18 | Jul 2024 – Mar 2026 | 99% 19 Mar 2026 |
| Oxygen, Dissolved as O2 9924 | River water | 18 | Jul 2024 – Mar 2026 | 10.9 mg/l 19 Mar 2026 |
| Temperature of Water 0076 | River water | 18 | Jul 2024 – Mar 2026 | 11.1 °C 19 Mar 2026 |
| pH 0061 | River water | 18 | Jul 2024 – Mar 2026 | 7.65 19 Mar 2026 |
| Ammoniacal Nitrogen as N 0111 | River water | 18 | Jul 2024 – Mar 2026 | below 0.03 mg/l 19 Mar 2026 |
| Nitrate as N 0117 | River water | 18 | Jul 2024 – Mar 2026 | 1.8 mg/l 19 Mar 2026 |
| Orthophosphate, reactive as P 0180 | River water | 18 | Jul 2024 – Mar 2026 | 0.011 mg/l 19 Mar 2026 |
| Conductivity at 25 C 0077 | River water | 18 | Jul 2024 – Mar 2026 | 251 µS/cm 19 Mar 2026 |
| Escherichia coli : Confirmed : MF 2348 | River water | 2 | Jan 2025 – Jan 2025 | 500 per 100 ml 29 Jan 2025 |
| Alkalinity to pH 4.5 as CaCO3 0162 | River water | 17 | Jul 2024 – Mar 2026 | 47 mg/l 19 Mar 2026 |
| Ammonia un-ionised as N 0119 | River water | 18 | Jul 2024 – Mar 2026 | below 0.00027 mg/l 19 Mar 2026 |
| Enterococci: Intestinal: Presumptive: MF 3722 | River water | 2 | Jan 2025 – Jan 2025 | 81 colony forming units / 100ml 29 Jan 2025 |
| MST Filtration 4926 | River water | 2 | Jan 2025 – Jan 2025 | DNA Stored 29 Jan 2025 |
| Nitrite as N 0118 | River water | 18 | Jul 2024 – Mar 2026 | below 0.004 mg/l 19 Mar 2026 |
| Nitrogen, Total as N 9686 | River water | 17 | Jul 2024 – Mar 2026 | 2 mg/l 19 Mar 2026 |
| Nitrogen, Total Oxidised as N 0116 | River water | 18 | Jul 2024 – Mar 2026 | 1.8 mg/l 19 Mar 2026 |
| Phosphorus, Total as P 0348 | River water | 17 | Jul 2024 – Mar 2026 | 0.015 mg/l 19 Mar 2026 |
| Solids, Suspended at 105 C 0135 | River water | 18 | Jul 2024 – Mar 2026 | 4.1 mg/l 19 Mar 2026 |
| Volume of Sample Filtered 4865 | River water | 2 | Jan 2025 – Jan 2025 | 840 millilitre 29 Jan 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.