Portontown Stream upstream of River Tamar
EA name: PORTONTOWN STREAM U/S RIVER TAMAR (also listed as “PORTONTOWN STREAM PRIOR TO RIVER TAMAR”)
Environment Agency sampling point SW-81251204 · 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 Mar 2026, 10:497 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
- 25 since 10 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 241430, 73730As published, to the nearest 10 m. Open in a map
- River, by its own name
- Portontown Stream
- River, by the map
- Not placedTwo watercourses within reach (7 m and 77 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) (23 samples)
Planned investigation (local monitoring) (2 samples)
Main measurements, river water
Dissolved oxygen
% saturation · code 9901 · %
99.4%
Sampled 3 Mar 2026, 7 months ago · 12 results banked
Every result (12)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Mar 2026, 10:49 | 99.4 | 99.4% |
| 10 Feb 2026, 10:48 | 98.6 | 98.6% |
| 12 Jan 2026, 10:49 | 102.1 | 102.1% |
| 10 Dec 2025, 10:27 | 102.3 | 102.3% |
| 5 Nov 2025, 11:21 | 100.5 | 100.5% |
| 7 Oct 2025, 10:40 | 97.6 | 97.6% |
| 9 Sep 2025, 10:29 | 97.4 | 97.4% |
| 12 Aug 2025, 10:45 | 97 | 97% |
| 3 Jul 2025, 10:40 | 99.4 | 99.4% |
| 2 Jun 2025, 10:46 | 103.7 | 103.7% |
| 6 May 2025, 11:00 | 101.9 | 101.9% |
| 2 Apr 2025, 10:45 | 102.4 | 102.4% |
Water temperature
code 0076 · °C
10.2 °C
Sampled 3 Mar 2026, 7 months ago · 12 results banked
Every result (12)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Mar 2026, 10:49 | 10.2 | 10.2 °C |
| 10 Feb 2026, 10:48 | 10.3 | 10.3 °C |
| 12 Jan 2026, 10:49 | 10 | 10 °C |
| 10 Dec 2025, 10:27 | 11.1 | 11.1 °C |
| 5 Nov 2025, 11:21 | 13.2 | 13.2 °C |
| 7 Oct 2025, 10:40 | 12.3 | 12.3 °C |
| 9 Sep 2025, 10:29 | 13.1 | 13.1 °C |
| 12 Aug 2025, 10:45 | 16 | 16 °C |
| 3 Jul 2025, 10:40 | 13.3 | 13.3 °C |
| 2 Jun 2025, 10:46 | 11.8 | 11.8 °C |
| 6 May 2025, 11:00 | 9.5 | 9.5 °C |
| 2 Apr 2025, 10:45 | 8.2 | 8.2 °C |
pH
code 0061
7.5
Sampled 3 Mar 2026, 7 months ago · 25 results banked
Every result (25)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Mar 2026, 10:49 | 7.5 | 7.5 |
| 10 Feb 2026, 10:48 | 7.5 | 7.5 |
| 12 Jan 2026, 10:49 | 7.5 | 7.5 |
| 10 Dec 2025, 10:27 | 7.4 | 7.4 |
| 5 Nov 2025, 11:21 | 7.3 | 7.3 |
| 7 Oct 2025, 10:40 | 7.6 | 7.6 |
| 9 Sep 2025, 10:29 | 7.7 | 7.7 |
| 12 Aug 2025, 10:45 | 7.7 | 7.7 |
| 3 Jul 2025, 10:40 | 7.7 | 7.7 |
| 2 Jun 2025, 10:46 | 7.6 | 7.6 |
| 6 May 2025, 11:00 | 7.7 | 7.7 |
| 2 Apr 2025, 10:45 | 7.79 | 7.79 |
| 26 Mar 2024, 12:01 | 7.57 | 7.57 |
| 13 Mar 2024, 11:32 | 7.51 | 7.51 |
| 22 Feb 2024, 10:30 | 7.58 | 7.58 |
| 1 Feb 2024, 11:35 | 7.61 | 7.61 |
| 31 Jan 2024, 13:48 | 7.4 | 7.4 |
| 15 Jan 2024, 12:08 | 7.55 | 7.55 |
| 11 Jan 2024, 12:04 | 7.49 | 7.49 |
| 18 Dec 2023, 12:02 | 7.48 | 7.48 |
| 7 Dec 2023, 13:24 | 7.02 | 7.02 |
| 20 Nov 2023, 12:09 | 7.77 | 7.77 |
| 16 Nov 2023, 15:02 | 7.33 | 7.33 |
| 17 Oct 2023, 11:44 | 7.2 | 7.2 |
| 10 Oct 2023, 13:07 | 7.07 | 7.07 |
Conductivity
at 25 °C · code 0077 · µS/cm
167 µS/cm
Sampled 3 Mar 2026, 7 months ago · 12 results banked
Every result (12)
| Sampled | Result as published | Reads as |
|---|---|---|
| 3 Mar 2026, 10:49 | 167 | 167 µS/cm |
| 10 Feb 2026, 10:48 | 160 | 160 µS/cm |
| 12 Jan 2026, 10:49 | 160 | 160 µS/cm |
| 10 Dec 2025, 10:27 | 164 | 164 µS/cm |
| 5 Nov 2025, 11:21 | 174 | 174 µS/cm |
| 7 Oct 2025, 10:40 | 196 | 196 µS/cm |
| 9 Sep 2025, 10:29 | 200 | 200 µS/cm |
| 12 Aug 2025, 10:45 | 213 | 213 µS/cm |
| 3 Jul 2025, 10:40 | 204 | 204 µS/cm |
| 2 Jun 2025, 10:46 | 195 | 195 µS/cm |
| 6 May 2025, 11:00 | 179 | 179 µS/cm |
| 2 Apr 2025, 10:45 | 193 | 193 µS/cm |
Everything measured here
46 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 46 rows
| Determinand | Material | Results | First – last | Latest result |
|---|---|---|---|---|
| Oxygen, Dissolved, % Saturation 9901 | River water | 12 | Apr 2025 – Mar 2026 | 99.4% 3 Mar 2026 |
| Temperature of Water 0076 | River water | 12 | Apr 2025 – Mar 2026 | 10.2 °C 3 Mar 2026 |
| pH 0061 | River water | 25 | Oct 2023 – Mar 2026 | 7.5 3 Mar 2026 |
| Conductivity at 25 C 0077 | River water | 12 | Apr 2025 – Mar 2026 | 167 µS/cm 3 Mar 2026 |
| Aluminium 6057 | River water | 1 | Apr 2025 – Apr 2025 | 100 µg/l 2 Apr 2025 |
| Aluminium, Dissolved 6037 | River water | 14 | Oct 2023 – Apr 2025 | 77 µg/l 2 Apr 2025 |
| Arsenic 6046 | River water | 1 | Apr 2025 – Apr 2025 | 8.9 µg/l 2 Apr 2025 |
| Arsenic, Dissolved 6045 | River water | 1 | Apr 2025 – Apr 2025 | 7.2 µg/l 2 Apr 2025 |
| Barium 6062 | River water | 1 | Apr 2025 – Apr 2025 | below 10 µg/l 2 Apr 2025 |
| Barium, Dissolved 9446 | River water | 12 | Apr 2025 – Mar 2026 | below 10 µg/l 3 Mar 2026 |
| Boron 6059 | River water | 1 | Apr 2025 – Apr 2025 | below 100 µg/l 2 Apr 2025 |
| Boron, Dissolved 9447 | River water | 12 | Apr 2025 – Mar 2026 | below 100 µg/l 3 Mar 2026 |
| Cadmium 0108 | River water | 12 | Apr 2025 – Mar 2026 | 0.21 µg/l 3 Mar 2026 |
| Cadmium, Dissolved 0106 | River water | 25 | Oct 2023 – Mar 2026 | 0.18 µg/l 3 Mar 2026 |
| Calcium 0241 | River water | 1 | Apr 2025 – Apr 2025 | 19 mg/l 2 Apr 2025 |
| Calcium, Dissolved 0239 | River water | 25 | Oct 2023 – Mar 2026 | 16 mg/l 3 Mar 2026 |
| Carbon, Organic, Dissolved as C :- {DOC} 0301 | River water | 24 | Oct 2023 – Mar 2026 | 0.97 mg/l 3 Mar 2026 |
| Chromium 3164 | River water | 1 | Apr 2025 – Apr 2025 | below 0.5 µg/l 2 Apr 2025 |
| Chromium, Dissolved 3409 | River water | 14 | Oct 2023 – Apr 2025 | below 0.5 µg/l 2 Apr 2025 |
| Copper 6452 | River water | 12 | Apr 2025 – Mar 2026 | 41 µg/l 3 Mar 2026 |
| Copper, Dissolved 6450 | River water | 25 | Oct 2023 – Mar 2026 | 33 µg/l 3 Mar 2026 |
| Hardness, Total as CaCO3 0158 | River water | 12 | Apr 2025 – Mar 2026 | 51.9 mg/l 3 Mar 2026 |
| Iron 6051 | River water | 1 | Apr 2025 – Apr 2025 | 93 µg/l 2 Apr 2025 |
| Iron, Dissolved 6460 | River water | 12 | Apr 2025 – Mar 2026 | 73 µg/l 3 Mar 2026 |
| Lead 0050 | River water | 11 | May 2025 – Mar 2026 | below 2 µg/l 3 Mar 2026 |
| Lead, Dissolved 0052 | River water | 25 | Oct 2023 – Mar 2026 | below 2 µg/l 3 Mar 2026 |
| Lithium 6064 | River water | 1 | Apr 2025 – Apr 2025 | below 100 µg/l 2 Apr 2025 |
| Lithium, Dissolved 4201 | River water | 12 | Apr 2025 – Mar 2026 | below 100 µg/l 3 Mar 2026 |
| Magnesium 0237 | River water | 1 | Apr 2025 – Apr 2025 | 4.3 mg/l 2 Apr 2025 |
| Magnesium, Dissolved 0235 | River water | 25 | Oct 2023 – Mar 2026 | 2.9 mg/l 3 Mar 2026 |
| Manganese 6050 | River water | 1 | Apr 2025 – Apr 2025 | 31 µg/l 2 Apr 2025 |
| Manganese, Dissolved 6458 | River water | 12 | Apr 2025 – Mar 2026 | 35 µg/l 3 Mar 2026 |
| Nickel 6462 | River water | 11 | May 2025 – Mar 2026 | 2.8 µg/l 3 Mar 2026 |
| Nickel, Dissolved 3410 | River water | 25 | Oct 2023 – Mar 2026 | 2.5 µg/l 3 Mar 2026 |
| pH : In Situ 3169 | River water | 10 | Jun 2025 – Mar 2026 | 7.59 3 Mar 2026 |
| Potassium 0211 | River water | 1 | Apr 2025 – Apr 2025 | 1.8 mg/l 2 Apr 2025 |
| Potassium, Dissolved 0209 | River water | 12 | Apr 2025 – Mar 2026 | 2.2 mg/l 3 Mar 2026 |
| Sodium 0207 | River water | 1 | Apr 2025 – Apr 2025 | 11 mg/l 2 Apr 2025 |
| Sodium, Dissolved 0205 | River water | 12 | Apr 2025 – Mar 2026 | 9.7 mg/l 3 Mar 2026 |
| Solids, Suspended at 105 C 0135 | River water | 12 | Apr 2025 – Mar 2026 | 4.8 mg/l 3 Mar 2026 |
| Strontium 6063 | River water | 1 | Apr 2025 – Apr 2025 | 41 µg/l 2 Apr 2025 |
| Strontium, Filtered 6693 | River water | 12 | Apr 2025 – Mar 2026 | 32 µg/l 3 Mar 2026 |
| Sulphate as SO4 0183 | River water | 1 | Apr 2025 – Apr 2025 | 19 mg/l 2 Apr 2025 |
| Sulphate, Dissolved as SO4 7859 | River water | 12 | Apr 2025 – Mar 2026 | 12 mg/l 3 Mar 2026 |
| Zinc 6455 | River water | 12 | Apr 2025 – Mar 2026 | 53 µg/l 3 Mar 2026 |
| Zinc, Dissolved 3408 | River water | 25 | Oct 2023 – Mar 2026 | 48 µg/l 3 Mar 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.