Mill Hill
EA name: MILL HILL (also listed as “RSN1210 MILL HILL”)
Environment Agency sampling point TH-RSN1210 · 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
- 17 Dec 2024, 15:0222 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 8 Oct 2026 and had nothing newer.
- Samples banked
- 11 since 2 Jan 2024 Imported periods: 1 Oct 2023 – 8 Oct 2026. Samples outside them are not shown here.
- Latest sample
- River / running surface water Monitoring (national agency policy)
- Where
- National Grid 468973, 221404As published, to the nearest 1 m. Open in a map
- River, by its own name
- Its name does not give one
- River, by the map
- River RayPlaced by position alone, on a line whose map name differs from its own, 1 m from the line.
- Next gauge downstream
- Grendon Underwood On the River Ray · 1.1 km along the river
- Why it was sampled
- Monitoring (national agency policy) (11 samples)
2 visits found no water to sample (recorded as “No flow”).
Main measurements, river water
Dissolved oxygen
% saturation · code 9901 · %
87.6%
Sampled 17 Dec 2024, 22 months ago · 9 results banked
Every result (9)
| Sampled | Result as published | Reads as |
|---|---|---|
| 17 Dec 2024, 15:02 | 87.6 | 87.6% |
| 7 Oct 2024, 14:19 | 37 | 37% |
| 13 Sep 2024, 12:43 | 84.4 | 84.4% |
| 18 Jul 2024, 11:54 | 69 | 69% |
| 23 May 2024, 09:52 | 66.4 | 66.4% |
| 24 Apr 2024, 11:49 | 75 | 75% |
| 14 Mar 2024, 13:39 | 94.3 | 94.3% |
| 23 Feb 2024, 12:34 | 90.9 | 90.9% |
| 2 Jan 2024, 11:19 | 77.7 | 77.7% |
Dissolved oxygen
as O2 · code 9924 · mg/l
10.4 mg/l
Sampled 17 Dec 2024, 22 months ago · 9 results banked
Every result (9)
| Sampled | Result as published | Reads as |
|---|---|---|
| 17 Dec 2024, 15:02 | 10.4 | 10.4 mg/l |
| 7 Oct 2024, 14:19 | 3.89 | 3.89 mg/l |
| 13 Sep 2024, 12:43 | 9.56 | 9.56 mg/l |
| 18 Jul 2024, 11:54 | 6.73 | 6.73 mg/l |
| 23 May 2024, 09:52 | 6.95 | 6.95 mg/l |
| 24 Apr 2024, 11:49 | 8.77 | 8.77 mg/l |
| 14 Mar 2024, 13:39 | 10.4 | 10.4 mg/l |
| 23 Feb 2024, 12:34 | 11.1 | 11.1 mg/l |
| 2 Jan 2024, 11:19 | 9.1 | 9.1 mg/l |
Water temperature
code 0076 · °C
7.6 °C
Sampled 17 Dec 2024, 22 months ago · 9 results banked
Every result (9)
| Sampled | Result as published | Reads as |
|---|---|---|
| 17 Dec 2024, 15:02 | 7.6 | 7.6 °C |
| 7 Oct 2024, 14:19 | 13 | 13 °C |
| 13 Sep 2024, 12:43 | 9.7 | 9.7 °C |
| 18 Jul 2024, 11:54 | 16.4 | 16.4 °C |
| 23 May 2024, 09:52 | 13.2 | 13.2 °C |
| 24 Apr 2024, 11:49 | 8.4 | 8.4 °C |
| 14 Mar 2024, 13:39 | 10.8 | 10.8 °C |
| 23 Feb 2024, 12:34 | 6.6 | 6.6 °C |
| 2 Jan 2024, 11:19 | 8.4 | 8.4 °C |
pH
code 0061
7.84
Sampled 17 Dec 2024, 22 months ago · 9 results banked
Every result (9)
| Sampled | Result as published | Reads as |
|---|---|---|
| 17 Dec 2024, 15:02 | 7.84 | 7.84 |
| 7 Oct 2024, 14:19 | 7.08 | 7.08 |
| 13 Sep 2024, 12:43 | 7.69 | 7.69 |
| 18 Jul 2024, 11:54 | 7.75 | 7.75 |
| 23 May 2024, 09:52 | 7.45 | 7.45 |
| 24 Apr 2024, 11:49 | 7.75 | 7.75 |
| 14 Mar 2024, 13:39 | 7.89 | 7.89 |
| 23 Feb 2024, 12:34 | 7.83 | 7.83 |
| 2 Jan 2024, 11:19 | 7.53 | 7.53 |
Ammonia
ammoniacal nitrogen as N · code 0111 · mg/l
0.13 mg/l
Sampled 17 Dec 2024, 22 months ago · 9 results banked
Every result (9)
| Sampled | Result as published | Reads as |
|---|---|---|
| 17 Dec 2024, 15:02 | 0.13 | 0.13 mg/l |
| 7 Oct 2024, 14:19 | 0.044 | 0.044 mg/l |
| 13 Sep 2024, 12:43 | <0.03 | below 0.03 mg/l (not detected above this) |
| 18 Jul 2024, 11:54 | 0.19 | 0.19 mg/l |
| 23 May 2024, 09:52 | 0.048 | 0.048 mg/l |
| 24 Apr 2024, 11:49 | 0.052 | 0.052 mg/l |
| 14 Mar 2024, 13:39 | 0.3 | 0.3 mg/l |
| 23 Feb 2024, 12:34 | 0.12 | 0.12 mg/l |
| 2 Jan 2024, 11:19 | 0.046 | 0.046 mg/l |
Nitrate
as nitrogen (N) · code 0117 · mg/l
2.87 mg/l
Sampled 17 Dec 2024, 22 months ago · 9 results banked
Every result (9)
| Sampled | Result as published | Reads as |
|---|---|---|
| 17 Dec 2024, 15:02 | 2.87 | 2.87 mg/l |
| 7 Oct 2024, 14:19 | 0.255 | 0.255 mg/l |
| 13 Sep 2024, 12:43 | 0.396 | 0.396 mg/l |
| 18 Jul 2024, 11:54 | 3.9 | 3.9 mg/l |
| 23 May 2024, 09:52 | 5.16 | 5.16 mg/l |
| 24 Apr 2024, 11:49 | 0.8 | 0.8 mg/l |
| 14 Mar 2024, 13:39 | 2.57 | 2.57 mg/l |
| 23 Feb 2024, 12:34 | 2.08 | 2.08 mg/l |
| 2 Jan 2024, 11:19 | 2.19 | 2.19 mg/l |
Phosphate
orthophosphate, reactive, as P · code 0180 · mg/l
0.045 mg/l
Sampled 17 Dec 2024, 22 months ago · 9 results banked
Every result (9)
| Sampled | Result as published | Reads as |
|---|---|---|
| 17 Dec 2024, 15:02 | 0.045 | 0.045 mg/l |
| 7 Oct 2024, 14:19 | 0.054 | 0.054 mg/l |
| 13 Sep 2024, 12:43 | 0.064 | 0.064 mg/l |
| 18 Jul 2024, 11:54 | 0.071 | 0.071 mg/l |
| 23 May 2024, 09:52 | 0.066 | 0.066 mg/l |
| 24 Apr 2024, 11:49 | 0.038 | 0.038 mg/l |
| 14 Mar 2024, 13:39 | 0.03 | 0.03 mg/l |
| 23 Feb 2024, 12:34 | 0.026 | 0.026 mg/l |
| 2 Jan 2024, 11:19 | 0.064 | 0.064 mg/l |
Conductivity
at 25 °C · code 0077 · µS/cm
1582 µS/cm
Sampled 17 Dec 2024, 22 months ago · 9 results banked
Every result (9)
| Sampled | Result as published | Reads as |
|---|---|---|
| 17 Dec 2024, 15:02 | 1582 | 1582 µS/cm |
| 7 Oct 2024, 14:19 | 598 | 598 µS/cm |
| 13 Sep 2024, 12:43 | 1632 | 1632 µS/cm |
| 18 Jul 2024, 11:54 | 959 | 959 µS/cm |
| 23 May 2024, 09:52 | 419 | 419 µS/cm |
| 24 Apr 2024, 11:49 | 1009 | 1009 µS/cm |
| 14 Mar 2024, 13:39 | 863 | 863 µS/cm |
| 23 Feb 2024, 12:34 | 667 | 667 µS/cm |
| 2 Jan 2024, 11:19 | 322 | 322 µS/cm |
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 | 9 | Jan 2024 – Dec 2024 | 87.6% 17 Dec 2024 |
| Oxygen, Dissolved as O2 9924 | River water | 9 | Jan 2024 – Dec 2024 | 10.4 mg/l 17 Dec 2024 |
| Temperature of Water 0076 | River water | 9 | Jan 2024 – Dec 2024 | 7.6 °C 17 Dec 2024 |
| pH 0061 | River water | 9 | Jan 2024 – Dec 2024 | 7.84 17 Dec 2024 |
| Ammoniacal Nitrogen as N 0111 | River water | 9 | Jan 2024 – Dec 2024 | 0.13 mg/l 17 Dec 2024 |
| Nitrate as N 0117 | River water | 9 | Jan 2024 – Dec 2024 | 2.87 mg/l 17 Dec 2024 |
| Orthophosphate, reactive as P 0180 | River water | 9 | Jan 2024 – Dec 2024 | 0.045 mg/l 17 Dec 2024 |
| Conductivity at 25 C 0077 | River water | 9 | Jan 2024 – Dec 2024 | 1582 µS/cm 17 Dec 2024 |
| Alkalinity to pH 4.5 as CaCO3 0162 | River water | 9 | Jan 2024 – Dec 2024 | 180 mg/l 17 Dec 2024 |
| Ammonia un-ionised as N 0119 | River water | 9 | Jan 2024 – Dec 2024 | 0.00138 mg/l 17 Dec 2024 |
| Carbon, Organic, Dissolved as C :- {DOC} 0301 | River water | 8 | Jan 2024 – Oct 2024 | 16 mg/l 7 Oct 2024 |
| Chloride 0172 | River water | 9 | Jan 2024 – Dec 2024 | 190 mg/l 17 Dec 2024 |
| Flow Type 2896 | River water | 5 | Jul 2024 – Dec 2024 | Moderate Flow 17 Dec 2024 |
| Nitrite as N 0118 | River water | 9 | Jan 2024 – Dec 2024 | 0.03 mg/l 17 Dec 2024 |
| Nitrogen, Total as N 9686 | River water | 9 | Jan 2024 – Dec 2024 | 4 mg/l 17 Dec 2024 |
| Nitrogen, Total Oxidised as N 0116 | River water | 9 | Jan 2024 – Dec 2024 | 2.9 mg/l 17 Dec 2024 |
| No flow /No sample 7668 | River water | 2 | Jun 2024 – Aug 2024 | No flow/discharge at sampling point 15 Aug 2024 |
| Phosphorus, Total as P 0348 | River water | 9 | Jan 2024 – Dec 2024 | 0.071 mg/l 17 Dec 2024 |
| Silica, reactive as SiO2 0182 | River water | 9 | Jan 2024 – Dec 2024 | 8.4 mg/l 17 Dec 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.