Groundwater levels in Oregon’s Klamath Basin have dropped as much as 25 feet in the past 15 years. A new report from the U.S. Geological Survey shows there is a relationship between the declines and pumping by farmers in the region.
Drought is a double-whammy for groundwater. Not only do farmers rely more on wells when rivers run low, there’s not much water available to seep back into, or recharge, the aquifer.
While a natural drop in the aquifer level would be expected in a decade of drought, data show groundwater use for crop irrigation by farmers in the federal Klamath Project hastened the decline.
But the report does not lay blame on farmers in the project. USGS Hydrologist Marshall Gannett said the story of groundwater in the Klamath basin is more complicated. Natural and climatic forces are at play, as well as irrigation and other pumping by other water users in the region.
“The pumping for the Project irrigators is one of many stresses on the groundwater system, and we can’t really tease those apart,” he said.
Still, Gannett said this is valuable information for farmers and water managers to have.
“You know you do need the long-term perspective, that’s for sure. And that oftentimes that can be pretty sobering, when you stop [step] back and see how your decisions have integrated over the past decade,” Gannett said.
The consequences of a dropping water table are starting to be felt locally.
“You see those declines, and you look at it almost as if it’s a bank. And if you see your bank account continuing to drop over time, you’ve got to assume you’re going to run out of money at some point,” said Klamath Watermaster Scott White.
It’s not that the wells are drying up, it’s that the water level underground is dropping too low for them to function.
“There are a few cases where folks have had to go in and deepen their wells, or even drill new wells. But I think in most circumstances, people are just having to lower their pumps, which is still a cost to the water user,” White said.
White said because of policy shifts, the number of wells and the volume of groundwater pumping increased dramatically beginning in 2001. In response, water officials have advised that groundwater pumping in the Klamath should not exceed 40,000 acre feet per year – about the equivalent of 20,000 Olympic-sized swimming pools. Klamath Project irrigators have exceeded recommended groundwater pumping levels eight of the past 14 years.
Even though groundwater levels naturally fluctuate – declining in drought, refilling in high-water years – White said it’s unclear whether the additional stresses irrigators and other users have put on groundwater supplies will have a long-term negative impact.
“We haven’t seen the aftermath of this, if it is truly cyclical,” he said. “But when we have these good water years, are those water levels going to recharge? We all hope and we all pray for that, but the answer is still unknown.”