Switzerland: Disruptions due to flooding ongoing across parts of Ticino and Valais cantons as of June 30

Disruptions due to flooding are ongoing across parts of Ticino and Valais cantons as of June 30. Heavy rainfall overnight June 29-30 triggered flooding in the regions, with the worst affected areas in parts of the Ticino Canton.

In the Ticino Canton, authorities reported at least two fatalities, and one other missing, as of June 30. Authorities reported a significant landslide in the Fontana area of the Maggia Valley near Locarno. Camping sites along the Maggia River were evacuated, and part of the small Visletto road bridge collapsed. Several areas in the region remain unreachable by road.

In the Valais Canton, authorities issued a red level warning (the second highest level on a five-tier scale) for flooding in areas along the Rhone River. The river burst its banks in several areas, flooding a highway and a railway line.

Response operations are ongoing, and lingering disruptions are likely in flood-affected areas over the coming days

Further sustained heavy rainfall could trigger additional flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed or a lack of stormwater drainage systems. Sites downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where the soil has become saturated by heavy rainfall.

Floodwaters and debris flows may render some bridges or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks. Severe weather could also trigger flight delays and cancellations at airports in the affected areas.

Flooding could heighten the threat of disease outbreaks. Backflow from drains mixed with floodwaters can become trapped in open areas when inundations recede. These stagnant pools often become a breeding ground for mosquitoes and bacteria, increasing the incidence of insect- and water-borne diseases. Exposure to contaminated water from inundated industrial sites, sewer systems, and septic tanks also poses a significant health threat.