Where this data meets Swiss law

1Residual flow: the floorGSchG Art. 31(1) · SR 814.20

Where water is taken from a watercourse with a permanent flow, a minimum must remain in the bed. The figure follows from Q₃₄₇, defined in Art. 4(h) as the discharge that, averaged over ten years, is reached or exceeded on 347 days of the year, and that is not substantially affected by damming, abstraction or diversion.

The calculator applies Art. 31(1) to the value entered. It does not determine the legally adequate residual flow. BAFU says modelled Q₃₄₇ values generally need local measurement, and the canton must also apply Art. 31(2) and Arts. 32–33. See BAFU's Q₃₄₇ guidance.

Computed from the table in Art. 31(1). Each band starts from the figure the statute states for it and rises at the rate the statute gives. The bands do not close exactly: a rate carried up to a boundary and the figure the statute states at that boundary differ by a fraction of a litre, 279.6 against 280 at 500 l/s and 2497.5 against 2500 at 10 000 l/s. At the boundary the stated figure governs. That is the statute's own arithmetic, reproduced and not smoothed.

2The floor moves, and it moves in two different waysGSchG Arts. 31(2), 32, 33

Upward, and it must. Art. 31(2) requires the minimum to be raised where five things are not otherwise secured: surface-water quality despite the abstraction and existing discharges; groundwater recharge sufficient for drinking water and the soil-water balance; rare habitats and communities that depend on the watercourse; the water depth free fish migration needs; and the spawning and rearing function of small streams with a Q₃₄₇ at or below 40 l/s below 800 m. Art. 33 raises it further, on a weighing of the public and economic interest in the abstraction against landscape and habitat value, water quality, the groundwater balance and agricultural irrigation.

Downward, and only within a closed list. Art. 33 is titled Erhöhung der Mindestrestwassermenge and does one thing: it raises. Going below the Art. 31 minimum is governed exclusively by Art. 32, whose grounds are exhaustive — short reaches above 1700 m with a Q₃₄₇ under 50 l/s, waters without fish down to 35 % of Q₃₄₇, reaches of a thousand metres with low ecological potential, an approved protection and use plan with compensating measures, and time-limited emergency takings. The Federal Supreme Court states the division in one sentence in BGE 145 II 140, E. 2: the minima are raised in the individual case on a comprehensive weighing of interests under Art. 33, and falling below them is admissible only in the exceptional cases of Art. 32.

3When Art. 31 bites, and when it does notGSchG Arts. 29, 80–83

This is the point on which the residual-flow layer of this map turns. Arts. 29–36 attach to an abstraction that needs a new permit or concession. An abstraction running under a concession already granted is governed instead by the transitional restoration regime, Arts. 80–83. And Art. 80(1) reaches only so far as restoration is possible without interference in existing water rights that would found a claim to compensation; Art. 80(2) allows more, against compensation under the expropriation act, where the watercourse is in an inventory or another overriding public interest requires it. So an existing plant may lawfully sit below the Art. 31 figure this map computes for its reach, and that is not a defect in the map: it is the gap the transitional regime creates.

The gap closes at renewal. BGer 1C_526/2015 of 12 October 2016, E. 3: once a concession has run out, abstractions must be newly licensed and must therefore comply in full with water-protection and environmental law, citing BGE 120 Ib 233; and the same applies where a running concession is so substantially altered that it amounts in substance to a new one, the rule laid down in BGE 119 Ib 254 (Curciusa). BGE 145 II 140 adds that even an immemorial water right cannot be perpetual: it ends without compensation once the investment is amortised, at the latest after eighty years, and continuation requires a fresh concession under current law exactly as for a new plant. BAFU puts the practical consequence on the face of its own Q₃₄₇ map, and most Swiss renewals fall between 2025 and 2050. The operative date for an abstraction on this map is its concession expiry, not today. That date is in the concession, and no federal open dataset carries it, which is why this map cannot draw it.

The restoration deadline has passed. Art. 82 required the cantons to inventory existing abstractions and report; Art. 81(2), as amended with effect from 1 January 2005, required that the restorations be completed by the end of 2012 at the latest. They were not. BAFU's latest national report, for the end of 2020, recorded 934 remediated cases, 91 % of the required total, with 94 outstanding. See the official report. The courts treat the lapsed deadline as raising the urgency of ordering restoration, not as a sanction — BGer 1C_526/2015, E. 3.5.1 and BGer 1C_185/2016, E. 2.2.2. This page does not determine whether a third party has an independent claim based on delay.

4Concession expiry and reversionWRG · SR 721.80

Art. 58 caps a concession at eighty years from the start of operation. Art. 43 makes it a vested right, withdrawable only in the public interest and against full compensation, which is the doctrinal reason Art. 80 GSchG and not Art. 31 governs mid-term. Art. 54(1) requires every concession to state its duration and the fate of the works at expiry, and Arts. 66–67 govern reversion: absent contrary terms the granting community may take the intake and diversion works free of charge and the generating works against fair compensation, and the concessionaire must keep the works operable until then.

5TemperatureGSchV Annex 2 No. 12(4) · SR 814.201

Die Temperatur eines Fliessgewässers darf durch Wärmeeintrag oder ‑entzug gegenüber dem möglichst unbeeinflussten Zustand um höchstens 3 °C, in Gewässerabschnitten der Forellenregion um höchstens 1,5 °C, verändert werden; dabei darf die Wassertemperatur 25 °C nicht übersteigen. Diese Anforderungen gelten nach weitgehender Durchmischung.

The rule concerns change caused by heat input or removal, compared with the least affected state after substantial mixing. Warm water alone does not establish breach. The map locates the question; the unaffected reference state and discharge point are still needed. The search found no Bundesgericht decision applying this provision on its merits. Published cases were adjacent, mainly sewer-fee disputes about cooling water.

The live screen uses a strict comparison: a fresh reported value above 25.0 °C is a review trigger; 25.0 °C itself is not labelled an exceedance. No alert is called a violation, because the live feed contains none of the attribution, reference-state, mixing, permit or exception evidence needed for that conclusion.

6Cooling water, and the carve-outGSchV Annex 3.3 No. 21(4)(b) · SR 814.201

Die Aufwärmung des Gewässers darf gegenüber dem möglichst unbeeinflussten Zustand höchstens 3 °C, in Gewässerabschnitten der Forellenregion höchstens 1,5 °C, betragen; dabei darf die Wassertemperatur 25 °C nicht übersteigen. Übersteigt die Wassertemperatur 25 °C, so kann die Behörde Ausnahmen zulassen, wenn die Erwärmung der Wassertemperatur höchstens 0,01 °C pro Einleitung beträgt oder die Einleitung von einem bestehenden Kernkraftwerk stammt.

Once-through cooling has its own regime, and it contains the sharpest sentence on this page: above the 25 °C ceiling the authority may allow an exception where the warming is at most a hundredth of a degree per discharge or the discharge comes from an existing nuclear power station. Three of the four sites on the water-use layer are still operating. No federal open dataset publishes their cooling volumes or their thermal load; those figures sit in the cantonal concession and in the operators' own reporting. The map can show you the gauge, the river and the site. The quantity has to be asked for.

6aWater quality evidenceGSchV Annex 2 · SR 814.201

The quality layer deliberately does not label a result a legal breach. Annex 2 contains parameter-specific requirements, and the legally relevant comparison can also depend on sampling duration, water use and method. A station-year median made for seeing the national record is not a substitute for that assessment. Open the station for the individual laboratory rows, then match them to the provision and factual setting that actually govern. BAFU explains the sampling and duration-dependent requirements for micropollutants on its official page.

6bWho must measure—and what the public record provesGSchG Arts. 50, 57–58 · SR 814.20

Federal law does not prescribe one identical checklist of parameters, sites and intervals for every canton or commune. The duty follows the task. The Confederation conducts surveys of national interest; cantons conduct the further surveys needed to apply water-protection law and report the results. Both must assess their measures and inform the public about the state of the waters.

Public evidence, canton by canton

The audit asks two reproducible questions: does the current national release contain a station in the canton, and what official cantonal programme, result or dataset is public? “Partial” means the linked record did not establish current, comprehensive surface-water results. It does not mean the canton failed to measure.

7Ecological goalsGSchV Annex 1 No. 1(3)(a) · SR 814.201

Die Wasserqualität soll so beschaffen sein, dass: a. die Temperaturverhältnisse naturnah sind.

A goal, not a limit value. It carries weight in the weighing of interests and in the reading of the numerical requirements, and it is the provision the glacier record speaks to most directly: a catchment that has lost half its ice does not have a near-natural thermal or flow regime, whatever any single gauge reads today.

8Who can put this in front of a courtNHG Art. 12 · USG Art. 55 · VBO

The ideelle Verbandsbeschwerde runs through three gates that in practice are one: NHG Art. 12 for organisations active throughout Switzerland pursuing purely ideal aims, for legal fields that have been their statutory purpose for ten years; USG Art. 55 for decisions on installations subject to an environmental impact assessment; and the VBO (SR 814.076), whose annex is the list that decides who actually has the right — see BGer 1C_15/2023 of 11 October 2024, which resolves standing by pointing at the annex entry. Since 1 August 2025 NHG Art. 12(1^bis) excludes standing against decisions on residential buildings under 400 m² in building zones, with exceptions.

Two categories of decision matter for this map. Concession grants and renewals are squarely challengeable — BGE 140 II 262, BGE 126 II 283, BGE 119 Ib 254. So are restoration orders under Art. 80 GSchG, and the Zurich Verwaltungsgericht has held that they are challengeable even where the order produces only ecological improvement (VB.2011.00070, E. 2.2.1 and 2.2.3). A purely local association generally cannot invoke Art. 12 NHG or Art. 55 USG; cantonal law may grant it standing separately.

9KlimaSeniorinnen, and what it does not yet doECtHR 53600/20

Verein KlimaSeniorinnen Schweiz and Others v. Switzerland, Grand Chamber, 9 April 2024: the association had standing, the four individual applicants did not, and Switzerland violated Art. 8 by failing to put in place the regulatory framework needed to address climate change, including any quantification of national emissions limits, and Art. 6 § 1 because the Swiss courts had not engaged with the arguments. The judgment requires general measures under Art. 46 § 2. Execution remains under enhanced supervision. In September 2025 the Committee of Ministers welcomed the legislative framework and noted that Switzerland had quantified future emissions by a method of its choice. It requested further information on independent review, access to court and later case law, with another review in 2026. See the Council of Europe state of play.

The judgment is relevant to positive climate obligations. It is not itself a Swiss water-law rule and this project has not established that a Swiss court has applied it to a water dispute.

What the record on this map is good for

The glacier inventories and twenty-six-year reservoir series are strong evidence of change, scale and timing. They do not establish that a named party caused it; causation needs separate evidence. For legal work, this map identifies the relevant reach, the age of each register and the quantities absent from open federal data.