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Columbia Plateau Aquifer Rapidly Shrinking

Gord McKenna
Koocanusa Reservoir, British Columbia

A comprehensive new study of a vast underground reservoir of water in central Washington confirms what irrigators and water district managers have known for years: the Columbia Plateau aquifer is rapidly shrinking.

The new report from the US Geological Survey is bleak. Hydrologists noted that the 44,000 square mile aquifer is essential to more than a million people and to Washington's $6 billion a year agricultural industry.

But the water is disappearing at an alarmingly faster rate.

The report said that groundwater pumping - largely for farm irrigation - has increased substantially since the 1970s and 80s, resulting in declining water levels and paltry groundwater recharge for rivers in the study area.

Even during years with average rain and snowfall, the pumping exceeds recharge.

USGS hydrologists studied water levels in more than 60,000 wells over the past hundred years. They found that in the past 40 years, 72% of them declined, with an average loss of nearly two feet a year.

Worse, they confirmed that there's not much surface water to replace the depleted underground supplies.

The report darkly concluded that significant changes are coming in the way water resources are managed in the largely arid area, although it stopped short of predicting what form the changes might take.