{"id":"england-river-water-quality","slug":"england-river-water-quality","name":"England River Water Quality Dataset","description":"Annual values for twenty-eight determinands at English river monitoring points — nutrients, oxygen and organic load, the major ions that describe a catchment’s geology, and eleven dissolved metals — computed from discrete laboratory samples in the Environment Agency Water Quality Archive.","methodology":"Individual sample results are read from the Water Quality Archive and reduced to annual figures per monitoring point. Results the laboratory reported as below its detection limit are excluded from the mean rather than counted as their limit or as zero, and a year is published only where such results were fewer than half of it and the year met the sample floor set for that determinand. pH and turbidity are published as annual medians rather than means, for different reasons: the pH scale is logarithmic, so arithmetic averaging of it is not a valid operation, while turbidity is dominated by storms, and a mean would report a single spate as the year. Nutrients keep the basis the Environment Agency reports them on — nitrate as nitrogen, orthophosphate as phosphorus — in their own metrics, rather than being converted into the ionic basis used by drinking-water standards. Metals are taken as the dissolved fraction only: the archive also publishes total concentrations including particle-bound metal, a modelled bioavailable fraction, and dry-weight concentrations in riverbed sediment measured in milligrams per kilogram, and mixing those would combine quantities differing by three orders of magnitude. The minimum number of samples a year must contain before it is published varies by determinand, because sampling frequency does: nutrients are sampled monthly at most points and metals commonly quarterly, so requiring the nutrient threshold of everything would have discarded the entire metals record rather than publishing a coarser one. Every published series carries its sample count, its censored share and, where the laboratory’s detection limit moved across the record, a note saying so — a falling limit changes how many results are censored without the water changing.","domains":["quality"],"metricIds":["nitrate-as-n","orthophosphate-as-p","ammoniacal-nitrogen","dissolved-oxygen","dissolved-oxygen-saturation","ph","water-temperature","conductivity","alkalinity","turbidity","suspended-solids","bod-5-day","dissolved-organic-carbon","total-oxidised-nitrogen","nitrite-as-n","total-phosphorus-as-p","lead-dissolved","cadmium-dissolved","mercury-dissolved","nickel-dissolved","zinc-dissolved","copper-dissolved","arsenic-dissolved","chromium-dissolved","iron-dissolved","manganese-dissolved","aluminium-dissolved","chloride-river","sulphate-river","sodium-dissolved","calcium-dissolved","magnesium-dissolved","potassium-dissolved"],"subjectScope":"English freshwater river monitoring points with at least ten years of record","cadence":"annual","version":"1.0.0","released":"2026-08-24","changelog":[{"version":"1.0.0","date":"2026-08-24","summary":"First release.","additions":["Annual values for six determinands at 4,846 English river monitoring points."]},{"version":"1.1.0","date":"2026-08-28","summary":"Expanded from six determinands to twenty-eight, and every series now carries its sample count, censored share and detection-limit history.","additions":["Chemistry: water temperature, conductivity, alkalinity, turbidity, suspended solids, biochemical oxygen demand and dissolved organic carbon.","Nutrients: total oxidised nitrogen, nitrite as N and total phosphorus as P, each kept apart from the determinand it resembles.","Eleven dissolved metals, including the Water Framework Directive priority substances lead, cadmium, mercury and nickel.","Six major ions describing catchment geology: chloride, sulphate, sodium, calcium, magnesium and potassium."]}],"limitations":["The archive’s public interface begins in 2000. The large improvement in English river chemistry that followed the Urban Waste Water Treatment Directive largely predates this and is not visible here.","Sampling frequency has fallen at many points over the period, so a national average computed year by year would partly measure which points were still being sampled rather than what was in the rivers.","These are river samples, not treated drinking water. Comparison against a drinking-water standard is a comparison between different things.","A concentration is specific to the point and the moment of sampling, and varies strongly with river flow.","Metals are the dissolved fraction. Environmental quality standards for several of them are written against a bioavailable fraction modelled from water chemistry, which is a different number and is not held, so these series describe exposure rather than compliance.","Metal series are heavily censored: in clean rivers most results sit below the laboratory detection limit. Those results are held as censored observations carrying their limit, and the annual mean is computed from the detected values only, which biases it upward by more the larger the censored share. Each series states that share.","Detection limits fell substantially over the record as instruments improved. A series whose censored share falls may be recording a laboratory getting better rather than a river getting cleaner, and the two cannot be separated from these data alone.","Escherichia coli results are read but no annual figure is published. Counts span orders of magnitude and rise sharply after rain, so an arithmetic mean is one storm and a median hides the storms; bathing water standards use percentiles of log-transformed counts, which is a method Hydrionis has not declared."],"observationCount":748160,"seriesCount":51207,"subjectCount":5214,"from":2000,"to":2025,"sourceIds":["uk-ea-wims"],"units":["%","NTU","mg/l","mg/l as C","mg/l as CaCO₃","mg/l as N","mg/l as P","mg/l as SO₄","pH","°C","µS/cm","µg/l"],"redistributable":true,"commerciallyReusable":true,"citation":"Hydrionis (2026), England River Water Quality Dataset, version 1.0.0. Retrieved from https://hydrionis.com/data/datasets/england-river-water-quality/","downloads":[{"file":"/downloads/observations-quality-uk-ea-wims.csv","format":"CSV","label":"quality observations from EA (471,154 rows)"},{"file":"/downloads/observations-chemistry-uk-ea-wims.csv","format":"CSV","label":"chemistry observations from EA (227,540 rows)"},{"file":"/downloads/observations-contaminant-uk-ea-wims.csv","format":"CSV","label":"contaminant observations from EA (60,193 rows)"}],"apiPath":"/api/v1/datasets/england-river-water-quality.json","lastFetched":"2026-08-28","fields":[{"id":"nitrate-as-n","name":"Nitrate as nitrogen","definition":"Concentration of nitrate in water expressed as the mass of nitrogen it contains, the convention used in environmental monitoring.","unit":"mg/l as N","nativeGeography":["monitoring-station"],"comparabilityNotes":"Reported as nitrogen, not as the nitrate ion: multiply by 4.43 to compare with a drinking-water standard written as NO₃. Concentrations are specific to the sampling point and vary strongly with river flow, so a wet year and a dry year are not directly comparable."},{"id":"orthophosphate-as-p","name":"Orthophosphate as phosphorus","definition":"Concentration of reactive orthophosphate expressed as the mass of phosphorus it contains.","unit":"mg/l as P","nativeGeography":["monitoring-station"],"comparabilityNotes":"Reported as phosphorus, not as the phosphate ion: multiply by 3.07 to express as PO₄. Reactive orthophosphate is a smaller quantity than total phosphorus, so the two must not be compared."},{"id":"ammoniacal-nitrogen","name":"Ammoniacal nitrogen","definition":"Combined concentration of ammonia and ammonium expressed as the mass of nitrogen, a standard indicator of recent organic or sewage pollution.","unit":"mg/l as N","nativeGeography":["monitoring-station"],"comparabilityNotes":"Reported as nitrogen rather than as the ammonium ion. The proportion present as toxic un-ionised ammonia rises sharply with pH and temperature, so the same concentration is not equally harmful in different rivers."},{"id":"dissolved-oxygen","name":"Dissolved oxygen","definition":"The concentration of oxygen dissolved in water, essential for aquatic life.","unit":"mg/l","nativeGeography":["monitoring-station","river-gauge"],"comparabilityNotes":"Oxygen solubility falls as temperature and salinity rise, so an absolute concentration must be read alongside temperature. Percentage saturation is often the more meaningful figure."},{"id":"dissolved-oxygen-saturation","name":"Dissolved oxygen saturation","definition":"Dissolved oxygen expressed as a percentage of the maximum the water could hold at its temperature and pressure.","unit":"%","nativeGeography":["monitoring-station","river-gauge"],"comparabilityNotes":"Saturation above 100% is not better than 100%. Strong daytime over-saturation and severe night-time depletion frequently occur in the same enriched river, and a daytime spot sample will not show the depletion."},{"id":"ph","name":"pH","definition":"The negative logarithm of hydrogen ion activity, measuring how acidic or alkaline water is.","unit":"pH","nativeGeography":["monitoring-station","supply-zone"],"comparabilityNotes":"pH varies with temperature and with dissolved carbon dioxide, so a sample measured hours after collection may not reflect the source. Averaging pH values arithmetically is strictly incorrect, since the scale is logarithmic."},{"id":"water-temperature","name":"Water temperature","definition":"Temperature of the water body or supply at the point of measurement.","unit":"°C","nativeGeography":["monitoring-station","river-gauge","supply-zone"]},{"id":"conductivity","name":"Electrical conductivity","definition":"The ability of water to conduct an electric current, proportional to its dissolved ion content.","unit":"µS/cm","nativeGeography":["monitoring-station","supply-zone"],"comparabilityNotes":"Conductivity is strongly temperature dependent and is conventionally reported normalised to 25 °C. An unnormalised reading is not comparable."},{"id":"alkalinity","name":"Alkalinity","definition":"The capacity of water to neutralise acid, dominated in most natural waters by bicarbonate and carbonate.","unit":"mg/l as CaCO₃","nativeGeography":["monitoring-station","supply-zone"]},{"id":"turbidity","name":"Turbidity","definition":"The cloudiness of water caused by suspended particles, measured by light scattering.","unit":"NTU","nativeGeography":["monitoring-station","supply-zone"],"comparabilityNotes":"Turbidity is an operational indicator, not a health parameter in itself, but it matters greatly because particles shield micro-organisms from disinfection."},{"id":"suspended-solids","name":"Suspended solids at 105 °C","definition":"Mass of particulate matter retained on a filter and dried at 105 °C, per litre of water.","unit":"mg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"Extremely flow-dependent: a single storm can carry more sediment than the preceding months, so a mean over samples taken on ordinary days understates the load a river actually moves. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"bod-5-day","name":"Biochemical oxygen demand (5 day, ATU)","definition":"Oxygen consumed by micro-organisms breaking down organic matter in a water sample over five days at 20 °C, with nitrification suppressed by allylthiourea.","unit":"mg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"Measured with nitrification suppressed, which is not the same test as an unsuppressed BOD and gives a lower number; the two must not be combined. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated."},{"id":"dissolved-organic-carbon","name":"Dissolved organic carbon","definition":"Concentration of organic carbon passing a filter, expressed as the mass of carbon.","unit":"mg/l as C","nativeGeography":["monitoring-station"],"comparabilityNotes":"Rising across much of upland Britain over recent decades, which is a genuine and much-studied change rather than a monitoring artefact. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"total-oxidised-nitrogen","name":"Total oxidised nitrogen as N","definition":"Combined concentration of nitrate and nitrite expressed as the mass of nitrogen.","unit":"mg/l as N","nativeGeography":["monitoring-station"],"comparabilityNotes":"Includes nitrite as well as nitrate, so it is always at least as large as nitrate alone and the two must not be plotted as one series. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"nitrite-as-n","name":"Nitrite as nitrogen","definition":"Concentration of nitrite expressed as the mass of nitrogen it contains.","unit":"mg/l as N","nativeGeography":["monitoring-station"],"comparabilityNotes":"Usually near or below the detection limit, so series are heavily censored. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"total-phosphorus-as-p","name":"Total phosphorus as P","definition":"Concentration of all forms of phosphorus, dissolved and particulate, expressed as the mass of phosphorus.","unit":"mg/l as P","nativeGeography":["monitoring-station"],"comparabilityNotes":"Always at least as large as orthophosphate at the same point and time, because it includes it. River phosphorus standards are written against orthophosphate, so this is the wrong series to compare against them. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"lead-dissolved","name":"Lead, dissolved","definition":"Concentration of lead passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river. Listed as a priority substance under the Water Framework Directive, so an environmental quality standard applies — but that standard is often written against the bioavailable fraction rather than this one."},{"id":"cadmium-dissolved","name":"Cadmium, dissolved","definition":"Concentration of cadmium passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river. Listed as a priority substance under the Water Framework Directive, so an environmental quality standard applies — but that standard is often written against the bioavailable fraction rather than this one."},{"id":"mercury-dissolved","name":"Mercury, dissolved","definition":"Concentration of mercury passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river. Listed as a priority substance under the Water Framework Directive, so an environmental quality standard applies — but that standard is often written against the bioavailable fraction rather than this one."},{"id":"nickel-dissolved","name":"Nickel, dissolved","definition":"Concentration of nickel passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river. Listed as a priority substance under the Water Framework Directive, so an environmental quality standard applies — but that standard is often written against the bioavailable fraction rather than this one."},{"id":"zinc-dissolved","name":"Zinc, dissolved","definition":"Concentration of zinc passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"copper-dissolved","name":"Copper, dissolved","definition":"Concentration of copper passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"arsenic-dissolved","name":"Arsenic, dissolved","definition":"Concentration of arsenic passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"chromium-dissolved","name":"Chromium, dissolved","definition":"Concentration of chromium passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"iron-dissolved","name":"Iron, dissolved","definition":"Concentration of iron passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"manganese-dissolved","name":"Manganese, dissolved","definition":"Concentration of manganese passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"aluminium-dissolved","name":"Aluminium, dissolved","definition":"Concentration of aluminium passing a filter, in the dissolved fraction of river water.","unit":"µg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"The dissolved fraction only. The archive also publishes a total concentration including metal bound to suspended particles, a modelled bioavailable fraction, and a dry-weight concentration in riverbed sediment measured in milligrams per kilogram; none of those is this, and mixing them confuses quantities that differ by orders of magnitude. Frequently reported as below the laboratory detection limit. Those results are held as censored observations carrying their limit rather than as zero or as the limit itself, and any statistic computed over them records how they were treated. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"chloride-river","name":"Chloride in river water","definition":"Concentration of chloride in river water.","unit":"mg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"A major ion, describing the geology and the human inputs a catchment carries rather than a pollutant in itself. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"sulphate-river","name":"Sulphate in river water","definition":"Concentration of sulphate in river water.","unit":"mg/l as SO₄","nativeGeography":["monitoring-station"],"comparabilityNotes":"A major ion, describing the geology and the human inputs a catchment carries rather than a pollutant in itself. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"sodium-dissolved","name":"Sodium, dissolved","definition":"Concentration of sodium in river water.","unit":"mg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"A major ion, describing the geology and the human inputs a catchment carries rather than a pollutant in itself. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"calcium-dissolved","name":"Calcium, dissolved","definition":"Concentration of calcium in river water.","unit":"mg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"A major ion, describing the geology and the human inputs a catchment carries rather than a pollutant in itself. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"magnesium-dissolved","name":"Magnesium, dissolved","definition":"Concentration of magnesium in river water.","unit":"mg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"A major ion, describing the geology and the human inputs a catchment carries rather than a pollutant in itself. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."},{"id":"potassium-dissolved","name":"Potassium, dissolved","definition":"Concentration of potassium in river water.","unit":"mg/l","nativeGeography":["monitoring-station"],"comparabilityNotes":"A major ion, describing the geology and the human inputs a catchment carries rather than a pollutant in itself. A river measurement, not a drinking-water one. River standards protect aquatic life and are written differently from the limits that apply to water leaving a treatment works, so this must never be read against a drinking-water limit. Specific to the sampling point and the moment the bottle was filled. River chemistry varies with flow, season and the distance below the last discharge, so a single result describes that reach on that day and not the river."}]}