Waterfall in Thousand Springs State Park, Hagerman Valley, Idaho, USA

Earth's most precious resource?. World Water Day

Groundwater surfaces in spectacular fashion at Thousand Springs State Park, in the aptly named Magic Valley of Idaho, USA. The springs are fed by the Eastern Snake Plain Aquifer, a huge reservoir of groundwater beneath the Snake River Plain. The groundwater here travels so slowly, it can take 150 to 250 years to flow from its source into Thousand Springs and the Snake River.

Since 1993, the UN has recognised 22 March as World Water Day, on which it highlights the need for sustainable freshwater supplies and other topics relevant to clean water and sanitation. This year, the theme is Groundwater – Making the Invisible Visible, drawing attention to this ‘hidden treasure’ which is a crucial source of drinking water and is used for irrigation worldwide.