Waters Protection Ordinance (WPO) (WPO)
Amended by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955).
English is not an official language of the Swiss Confederation. This translation is provided for information purposes only and has no legal force.
Section 1 Space provided for Waters and Rehabilita
Inserted by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955). See also the Transitional Provision to this amendment at the end of the text.
Art. 41a Space provided for watercourses
1 In biotopes of a national importance, in cantonal nature conservation areas, in mire landscapes of exceptional beauty and national importance, in water bird and migratory bird reserves of international or national importance and, in the case of waters-related protection targets, in landscapes of national importance and cantonal landscape conservation areas the width of the space provided for waters must amount to at least: a. for watercourses with a channel bed of less than 1 m natural width: 11 m; b. for watercourses with a channel bed of 1–5 m natural width: 6 times the width of the channel bed plus 5 m; c. for watercourses with a channel bed of more than 5 m natural width: the width of the channel bed plus 30 m. 2 In other areas, the width of the space provided for waters must amount to at least: a. for watercourses with a channel bed of less than 2 m natural width: 11 m; b. for watercourses with a channel bed of 2–15 m natural width: 2.5 times the width of the channel bed plus 7
Para. 4 let. b let. 2 — Amended by No I of the O of 22 March 2017, in force since 1 May 2017 (AS 2017 2585). Para. 5 let. d — Inserted by No I of the O of 22 March 2017, in force since 1 May 2017 (AS 2017 2585).
Art. 41b Space provided for standing waters
1 The width of the space provided for waters must amount to at least 15 m measured from the shoreline. 2 The width of the space provided for waters calculated in accordance with paragraphs 1 must be increased where this is required to guarantee: a. protection against flooding; b. the space required for rehabilitation; c. overriding interests of the nature- and landscape conservation; d. the use of the waters. 3 The width of the space provided for waters may be adapted to the structural conditions in densely built-up areas provided protection against flooding is guaranteed. 4 In the absence of any overriding interests to the contrary, determining the space provided for waters may be dispensed with if the waters: a. are located in forest or in areas, that are not designed mountain- or valley areas in accordance with the agriculture legislation in the arable land register; b. have a surface area of less than 0.5 ha; or c. are artificially laid out.
Art. 41c Extensive structuring and management of the space provided for waters
1 In the space provided for waters, only fixed installations serving the public interest such as footpaths and hiking trails, run-of-river power plants or bridges may be built. The authority may authorise the following installations provided there are no overriding interests to the contrary: in densely built-up areas, installations that meet zoning requirements; abis. installations that meet zoning requirements outside densely built-up areas on individual plots of ground that have not been built on within a series of several plots of ground that have been built on; b. agricultural and forestry tracked and gravel paths with a distance of at least 3m from the shoreline of the waters if topographically limited spatial conditions pertain; c. fixed parts of installations that aid water withdrawal or discharge; d. small installations that serve the use of the waters. 2 The continued existence of installations and permanent crops in terms of Article 22 paragraph 1 letters a–c, e and g–i of th
Para. 1 let. abis — Inserted by No I of the O of 22 March 2017, in force since 1 May 2017 (AS 2017 2585). Para. 1 let. d — Inserted by No I of the O of 22 March 2017, in force since 1 May 2017 (AS 2017 2585). Para. 1 let. d — Amended by No I of the O of 4 Nov. 2015, in force since 1 Jan. 2016 (AS 2015 4791). Para. 2 — SR 910.91 Para. 2 — Amended by No I of the O of 4 Nov. 2015, in force since 1 Jan. 2016 (AS 2015 4791). Para. 4 — SR 910.13 Para. 4 — Amended by No IV of the O of 2 Nov. 2022, in f
Art. 41cbis Farming land with the quality of crop rotation areas in the space provided for waters
1 Arable farming land with the quality of crop rotation areas in the space provided for waters must be shown separately by the cantons when making the inventory of crop rotation areas in accordance with Article 28 of the Spatial Planning Ordinance of 28 June 2000. It may continue to be included in the cantonal minimum of crop rotation areas. If a related federal decree is issued (Art. 5 WPA), these areas may be intensively farmed in emergency situations. 2 Alternative land must be provided in accordance with the sectoral plan for crop rotation areas (Art. 29 of the Spatial Planning Ordinance of 28 June 2000) in compensation for arable farming land with the quality of crop rotation areas in the space provided for waters that is required to implement structural flood protection or rehabilitation measures.
Art. 41cbis — Inserted by No I of the O of 4 Nov. 2015 (AS 2015 4791). Amended by No I of the O of 22 March 2017, in force since 1 May 2017 (AS 2017 2585). Para. 1 — SR 700.1
Art. 41cter Preservation or restoration of the natural course
In the event of operations on surface waters, the natural course of the watercourse, which is characterised by its position in the cross-section of the valley, its longitudinal slope, its channel shape, its bed width and its morphological structures and dynamic processes, must as far as possible be preserved or restored.
Art. 41cter — Inserted by Annex No 3 of the Hydraulic Engineering O of 25 June 2025, in force since 1 Aug. 2025 (AS 2025 450).
Art. 41cquater Ecological development and maintenance
1 Waters and the space provided for waters must be developed and maintained in such a way that habitats typical of the location are preserved and able to develop. habitats typical of the location are based on: a. vegetation that develops naturally and regenerates itself; b. characteristic dynamic processes; c. characteristic structures, such as gravel bars, natural and variable banks and deadwood. 2 When developing and maintaining waters and the space provided for waters excessive warming of the water must be avoided. In particular, natural shade should be encouraged.
Art. 41cquater — Inserted by Annex No 3 of the Hydraulic Engineering O of 25 June 2025, in force since 1 Aug. 2025 (AS 2025 450).
Art. 41d Planning of rehabilitation projects
1 The cantons shall devise the principles required to plan the rehabilitation of watercourses. The principles shall include information on the following in particular: a. the ecomorphological condition of the waters; b. the installations in the space provided for waters; c. the ecological potential and the agricultural importance of the waters. 2 They shall set out in a plan for a period of 20 years the stretches of water to be rehabilitated, the form of the rehabilitation measures and the deadlines by which the measures must be implemented, and shall coordinate the plan with the neighbouring cantons to the extent that this is required. Rehabilitation projects shall primarily be planned where their benefits: a. are substantial for nature and the landscape; b. are substantial compared with the probable cost; c. may be increased through coordination with other measures to protect natural habitats or to prevent flooding. 3 They shall adopt the plans under paragraph 2 for watercourses by 3
Para. 3 — Amended by No I 4 of the O of 28 Jan. 2015 on Amendments to Secondary Legislation on the Environment, in particular in relation to the programme agreements for the programme period 2016-2019, in force since 1 Jan. 2016 (AS 2015 427).
Section 2 Hydropeaking
Inserted by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955).
Art. 41e Serious harm due to hydropeaking
There is serious harm to indigenous flora and fauna and to their habitats due to hydropeaking where: a. the flow rate for upsurge is at least 1.5 times greater than for downsurge; and b. the site-specific quantity, composition and diversity of the plant and animal communities are changed to their detriment, in particular because regularly and in an unnatural manner fish are run ashore, fish spawning grounds are destroyed, aquatic animals are washed away, turbidity arises or the water temperature is altered in an unlawful manner.
Art. 41f Planning remediation measures for hydropeaking
1 The cantons shall submit to the FOEN a plan for measures to remediate hydropower plants that cause hydropeaking in accordance with the procedure described in Annex 4a number 2. 2 The persons responsible for hydropower plants must grant access to the authority responsible for the plan and provide the required information, in particular on: a. the coordinates and the designation the individual parts of the plant; b. the flow rates of the watercourse concerned with measured values at intervals of no more than 15 minutes (hydrograph) over a period covering the past five years; If these measured values are not available, the hydrograph may be calculated using data relating to hydro-electric power production at the plant and the water flow; c. the measures carried out and planned to reduce the effects of hydropeaking; d. the available results of the study on the effects of hydropeaking; e. the planned structural and operational changes at the plant.
Art. 41g Remediation measures for hydropeaking
1 Based on the measures plan, the cantonal authority shall order the remediation of hydropeaking and require the persons responsible for hydropower plants to examine various types of remediation measure in order to implement the plan. 2 Before it decides on the remediation project, it shall consult the FOEN. With a view to an application under Article 30 paragraph 1 of the Energy Ordinance of 1 November 2017 (EnO), the FOEN shall verify whether the criteria of Annex 3 number 2 EnO are met. 3 The persons responsible for hydropower plants shall verify the effectiveness of the measures taken as required by the authority.
Para. 2 — SR 730.01 Para. 2 — Second sentence amended by Annex 7 No II 2 of the Energy Ordinance of 1 Nov. 2017, in force since 1 Jan. 2018 (AS 2017 6889).
Section 3 Flushing out and Emptying of Impoundment
Inserted by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955).
Art. 42 ...
1 Before an authority authorises the flushing out or emptying of an impoundment, it shall ensure that sediments are removed other than by washing away if this is environmentally compatible and economically acceptable. 2 When washing away sediments the authorities shall ensure that communities of plants, animals and micro-organisms are harmed as little as possible, in particular by laying down: a. time and type of flushing out or emptying; b. the maximum concentration of suspended matter in the water which must be respected during the flushing out or emptying; c. to what extent washing away must be carried out so that during the flushing out or emptying, fine matter deposited in watercourses is removed. 3 Paragraphs 1 and 2 do not apply to the abrupt lowering of the water level following an exceptional event (Art. 40 para. 3 WPA).
Art. 42 — Repealed by No I of the O of 4 May 2011, with effect from 1 June 2011 (AS 2011 1955).
Section 4 Bed Load Budget
Inserted by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955).
Art. 42a Serious harm due to change in the bed load budget
A change in the bed load budget causes serious harm to the indigenous flora and fauna and their habitats if installations such as hydropower plants, gravel excavation sites, bed load traps or river control structures alter the morphological structures or the morphological dynamics of the waters to their detriment.
Art. 42a — Inserted by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955).
Art. 42b Planning the measures to remediate the bed load budget
1 The cantons shall submit a plan to the FOEN of their measures to remediate the bed load budget in accordance with the procedure described in Annex 4a number 3. 2 The persons responsible for installations must allow access to the authority responsible for the plan and provide the required information, in particular on: a. the details and the designation of the installations and in the case of hydropower plants the individual parts of the installation; b. how the bed load is dealt with; c. the measures carried out and the planned in order to improve the bed load budget; d. the available results of the study of the bed load budget; e. the planned structural and operational changes to the installation.
Art. 42b — Inserted by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955).
Art. 42c Measures to remediate the bed load budget
1 In the case of installations which according to the plan require measures to remediate the bed load budget, the cantons shall prepare a study on the nature and extent of the required measures. 2 Based on the study, the cantonal authority shall in accordance with paragraph 1 order the remediation measures. In the case of hydropower plants, the bed load must wherever possible be made to pass through the installation. 3 Before it decides on the remediation project in the case of hydropower plants, it shall consult the FOEN. The FOEN shall examine with a view to an application under Article 30 paragraph 1 EnO whether the criteria of Annex 3 number 2 EnO are met. 4 The persons responsible for hydropower plants shall verify the effectiveness of the measures taken in accordance with instructions from the cantonal authority.
Art. 42c — Inserted by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955). Para. 3 — SR 730.01 Para. 3 — Second sentence amended by Annex 7 No II 2 of the Energy Ordinance of 1 Nov. 2017, in force since 1 Jan. 2018 (AS 2017 6889).
Art. 43 Extraction of gravel, sand and other materials from watercourses
1 In order that the bed load budget in a watercourse is not unfavourably influenced by extraction of gravel, sand or other materials (Art. 44 para. 2 let. c WPA), the authorities must ensure that: a. the quantity of bed load extracted from the watercourse does not exceed the natural supply; b. the extraction does not in the long term lead to a subsidence of the bottom outside the extraction perimeter; c. the extraction does not render impossible the maintenance and re-establishment of inventoried floodplains; d. the extraction does not lead to a substantial change in the particle size distribution of the bottom material outside the extraction perimeter. 2 Extraction according to paragraph 1 should not lead to turbidity that may impair fishing waters.
Section 5 Drainage Water from Underground Building
Inserted by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955).
Art. 44 ...
1 Drainage water from underground buildings must be contained and channelled off in such a way that it cannot be polluted by such construction operations, in particular by exceptional events. This does not apply to small amounts of drainage water if retention measures prevent the pollution of the receiving waters. 2 For the discharge of drainage water from underground buildings into watercourses, the following applies: a. the spillway construction must be such as to ensure homogeneous and rapid mixing of the water; b. the temperature of the receiving waters must not be raised over its near as possible natural state by more than 3 °C; if the stretch belongs to a trout zone, the temperature must not be raised by more than 1.5 °C; c. the discharge must not result in the water temperature exceeding 25 °C. 3 Depending on local circumstances the authorities shall specify: a. requirements for discharge into lakes and infiltration; b. additional requirements for discharge into watercourses if
Art. 44 — Repealed by No I of the O of 4 May 2011, with effect from 1 June 2011 (AS 2011 1955).
