Cheltenham River Water Quality
Chemical water quality readings for the River Chelt and nearby brooks, from the Environment Agency's Water Quality Archive.
- 9 sampling points within 6.0 miles
River Water Quality Around Cheltenham
The Environment Agency periodically samples rivers and brooks for a batch of chemical determinands — pH, temperature, nutrients like nitrate and ammoniacal nitrogen, and others — testing each sampling point roughly once a month. This page shows every determinand from the most recent visit to each open river sampling point within 6.0 miles of Cheltenham, covering the River Chelt and the brooks that feed it, and the nearby Swilgate, Isbourne and Leigh Brook.
This is chemical water quality, not sewage discharge activity — see our sewage overflow status page for that — and it isn’t a flood risk indicator either; see flood warnings for that.
Water Incidents
Map
Latest Readings
Frequently Asked Questions
What Is a "Determinand"?
- The Environment Agency's term for a specific substance or property measured in a water sample — pH, temperature, or the concentration of a particular chemical like nitrate. Each sampling visit tests a batch of them at once, which is why one visit produces many rows on the table above.
What Do the Common Determinands Mean?
- Here's what the most common readings on this page mean:
- pH — how acidic or alkaline the water is, on a 0-14 scale; most healthy rivers sit around neutral, roughly 6.5-8.5.
- Temperature of Water — in degrees Celsius; sustained high temperatures can lower how much oxygen the water holds.
- Oxygen, Dissolved as O2 / % Saturation — how much oxygen is available for fish and other aquatic life; low values can indicate pollution or algal blooms.
- Ammoniacal Nitrogen as N / Ammonia un-ionised as N — nitrogen from sources like sewage or agricultural runoff; higher levels can be toxic to fish.
- Nitrate as N / Nitrite as N / Nitrogen, Total Oxidised as N — other nitrogen compounds, often from fertiliser runoff or treated sewage effluent.
- Orthophosphate, reactive as P / Phosphorus, Total as P — phosphorus compounds, a common cause of excessive plant and algae growth when levels are high.
- BOD : 5 Day ATU (Biochemical Oxygen Demand) — how much oxygen microorganisms use breaking down organic matter in the sample over 5 days; a higher figure suggests more organic pollution.
- Conductivity at 25 C — how well the water conducts electricity, a general indicator of dissolved mineral/salt content.
- Metals (Cadmium, Lead, Nickel, etc), Chloride, Calcium, Magnesium, Silica and Suspended Solids are also routinely tested for; specialist reference values exist for each but are outside the scope of this page.
About This Data
Data from Environment Agency Water Quality Archive, published under the Open Government Licence v3.0. Last updated 11 October 2026, checked monthly. Each sampling point is only tested periodically (roughly monthly), so the "Sample Date" is when that point was last visited, not when this page was updated.
What Does a Value like "<0.03" Mean?
- The substance was tested for but not detected above the laboratory's detection limit — the true value is somewhere below the number shown, not exactly that number.
What About "GCMS Screen", "LCMS Screen" or "Non Target Screening"?
- These are broad laboratory screening tests for a wide range of chemicals at once (pesticides, industrial compounds and similar), reported as "Semi Quantitative" or a plain presence/absence result rather than a single concentration value — hence values like "1" with a unit of "Text".
Where Does the Data Come From?
- The Environment Agency's Water Quality Archive, released under the Open Government Licence v3.0.