Tay — monitoring and records

The monitoring network on this water

Hydrionis holds 2,766 values from 4 gauges on this water. Discharge is a property of a gauge and its reach, not of this water as a whole, so this page reports the network and its records rather than a single figure.

Gauges

2,766

Values held

1952–2026

Record spans

Gauges on the Tay

4 monitoring points, positioned as the publisher records them.

The seasonal shape

An annual mean says how much water a river carried. A monthly record says when — and on most rivers the difference between a wet winter and a dry summer is larger than the difference between one year and the next.

Monthly mean flow at Ballathie

Each month's mean discharge as the publisher computed it, which shows the seasonal shape an annual mean flattens away. 1952–2026.

Show relevant events (1 event)Shading marks when something was recorded, not what caused the line.

Taken as the publisher computes it rather than recomputed by Hydrionis from daily values: the publisher knows which of its readings passed validation. Months the gauge did not cover are absent rather than interpolated, and the line breaks where they fall.

What the shaded periods are (1 event)

A shaded period marks when something was recorded, not what caused the shape of the line. Where the two coincide, they coincided.

Documented record — A documented event, compiled from cited sources after it happened. The dates are as good as the record, which for older events can mean the month rather than the day.

Event	Type	Period	Standing	Authority
European drought	Drought declaration	2022-05-01 – 2022-10-31	Documented record	Compiled record

Not shown on this chart

The 1976 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
The 2022 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Yorkshire drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cantareira water crisis, São Paulo — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cape Town Day Zero — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Hurricane Katrina water and sanitation collapse — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.

View the data behind this chart

Underlying data
Period	Ballathie (m³/s)
1952	142
1953	144
1954	202
1955	177
1956	194
1957	345
1958	200
1959	159
1960	248
1961	214
1962	297
1963	92.9
1964	135
1965	266
1966	203
1967	219
1968	175
1969	216
1970	226
1971	252
1972	308
1973	184
1974	516
1975	403
1976	244
1977	183
1978	169
1979	162
1980	170
1981	299
1982	247
1983	471
1984	316
1985	126
1986	282
1987	215
1988	344
1989	328
1990	333
1991	325
1992	293
1993	564
1994	303
1995	299
1996	261
1997	93.5
1998	305
1999	381
2000	354
2001	211
2002	301
2003	207
2004	323
2005	494
2006	226
2007	454
2008	467
2009	252
2010	150
2011	233
2012	349
2013	254
2014	500
2015	399
2016	598
2017	166
2018	245
2019	126
2020	314
2021	169
2022	183
2023	328
2024	353
2025	213
2026	399

About this series

Everything below is a property of the data rather than a rating of it. There is deliberately no single confidence score: how much a gap matters depends on what you are about to do with the series, and only you know that.

Source	Scottish Environment Protection Agency — SEPA water environment data · Open Government Licence v3.0
How the values came to exist	Measured
Period held	1952–2026
Completeness	100.0% of the periods in that span are held.
Continuity	Continuous: every year from 1952 to 2026 is held.
Last read from the publisher	2026-10-05
Redistribution	Permitted by the upstream licences
Commercial reuse	Permitted by the upstream licences. No Hydrionis access tier can widen this.
Methodology	How this was produced

Every gauge Hydrionis holds here

Gauges on the Tay and what each holds
Gauge	Measures	Values	Record
Ballathie	mean monthly river flow	888	1952–2026
Pitnacree	mean monthly river flow	828	1957–2026
Kenmore	mean monthly river flow	621	1974–2026
Caputh	mean monthly river flow	429	1991–2026

How these gauges were attached to this water

Named by the publisher Each gauge here names this water in the publisher’s own station record. Hydrionis has not inferred the connection from station names.

What each gauge’s link to this water rests on
Gauge	Evidence	Established
Ballathie	Stated by the publisher — SEPA KiWIS station list, river_name and catchment_name fields — https://timeseries.sepa.org.uk/KiWIS/KiWIS	2026-10-02
Pitnacree	Stated by the publisher — SEPA KiWIS station list, river_name and catchment_name fields — https://timeseries.sepa.org.uk/KiWIS/KiWIS	2026-10-02
Kenmore	Stated by the publisher — SEPA KiWIS station list, river_name and catchment_name fields — https://timeseries.sepa.org.uk/KiWIS/KiWIS	2026-10-02
Caputh	Stated by the publisher — SEPA KiWIS station list, river_name and catchment_name fields — https://timeseries.sepa.org.uk/KiWIS/KiWIS	2026-10-02

What this record holds

Hydrionis decides which waters get a page, and which of those are offered to search, from what is actually held rather than from how the page reads. Five signals are counted; this record has 3 of them, which makes it a full profile.

Information-gain signals held for this water body
Signal	Held	Counts
Gauges holding a real record	4	yes, 3 or more
Years spanned	75	yes, 20 or more
Values held	2,766	yes, 1000 or more
Distinct measurements	1	no
Publishers measuring it	1	no
Official identifiers	0	recorded, not counted

Use this data

Machine-readable JSON /api/v1/observations/by-subject/sepa-gauge-14937.json
How to cite this, and who you must credit
How these figures were produced
Request this at a different scale, format or geography

No bulk download is offered here, which is a licence position rather than a product one: at least one contributing publisher does not permit redistribution. The values can be read on the page, cited, and pointed to at source.

Attribution and citation

Attribution you are required to give

These are conditions of the licences the underlying data is published under. They are obligations to the publishers, not to Hydrionis, and they apply to you directly whether or not you mention Hydrionis at all.

Contains public sector information licensed under the Open Government Licence v3.0.

Scottish Environment Protection Agency — Open Government Licence v3.0 (licence text)

Suggested citation for Hydrionis

Hydrionis (2026), Tay gauge records, accessed 2026-10-05, hydrionis.com/waters/scotland-tay/

Cite Hydrionis where you rely on the compilation, the normalisation, the eligibility judgements or a chart. Where you use an unmodified published value, the publisher’s attribution is the one that is required; crediting Hydrionis as well is welcome and is not something Hydrionis can require of you.

Recommended, not required. Hydrionis does not claim rights over unmodified public data it relayed, and doing arithmetic on somebody else’s measurements does not make them Hydrionis’s. Cite the version and the access date: the Tay gauge records changes as publishers release and as methods are revised, and a citation without both cannot be checked later. Full guidance is on cite and reuse.

Where these figures come from

Spatially aggregatedHigh confidenceSeptember 2026

Source: SEPA — SEPA water environment data, 14937. Licence: Open — attribution required (attribution required).

Method: Monthly mean computed by Hydrionis from SEPA daily mean flow. Months with fewer than 20 days of record are not published rather than averaged from a partial month.

Flow is a property of this gauge and this reach, not of the river as a whole.

Retrieved 5 October 2026.