Groundwater - How much can we use?
Study shows how much irrigators can pump year after year without depleting the aquifer
In July 2010, city of Merrill residents found their faucets dry. The aquifer had dropped below the city’s well head and for several days, while the city hurried to install pipes deeper in the well, residents had to use bottled water to cook, clean and drink.
It was a wake-up call.
Irrigators on the Klamath Reclamation Project had pumped more than 100,000 acre-feet of water that summer to combat a drought, dropping the aquifer 10 to 20 feet in some places.
A study released earlier this month aims to help irrigators better manage groundwater pumping. U.S. Geological Survey hydrologists have been studying the Klamath Basin for 13 years, and have concluded that Project irrigators can sustainably pump large amounts of groundwater, but only about half of what they did in 2010. “ There is a substantial resource there and it can provide water for the longterm,” said Marshall Gannett, a USGS hydrologist who has spent half of his career studying the Basin. “(Groundwater) can be managed in a way that you can get substantial volumes of water when you need it in dry years.”
Like Mer r ill, K lamath Falls and Malin get their drinking water from wells. But the a mount pumped in municipal wells pales in comparison to agricultural wells, Gannett said.
G r o u n d wat e r p u mp - ing on the K lamath Project is relatively new, and until now, the impact on t he aqu i fer wa s mo st ly speculative. Irrigators dug wells throughout the Basin i n 2 0 01, when a severe drought left them without any surface water.
The Tulelake Irrigation District dug 10 wells that year and has seen a steady drop in the aquifer since then, especially after 2010, said Brad Kirby, assistant to the district manager.
Like most irrigation districts, Tulelake only pumps its wells in dry years when surface water is curtailed. T he US G S st udy shows how much irrigators can pump in such years without irreparably depleting the g roundwater system, said Greg Addington, executive director of the Klamath Water Users Association.
“We don’t want to permanently damage the aquifer of the small communities that depend on wells,” he said.
40,000 acre-feet likely to be pumped
Irrigators say study will help during drought years
by JOEL ASCHBRENNER, Herald and News 5/24/12
H&N photo by Joel Aschbrenner. Tulelake Irrigation District assistant manager Jerry Pyle stands near a district irrigation pump that is used to pump groundwater in dry years.
For more than a decade, irrigators on the Klamath Reclamation Project have pumped wells to supplement surface water in dry years.
They didn’t know exactly how they were affecting the aquifer, but learned there were limits on how much they could pump.
In 2010, Project irrigators pumped more than 100,000 acre-feet of groundwater and dropped the water table 10 to 20 feet in places. “That wasn’t sustainable,” said Hollie Cannon, executive director of the Klamath Water and Power Agency.
This year, with another water shortage projected, KWAPA plans to have Project irrigators pump 40,000 acre feet.
A recently released study from the U.S. Geological Survey shows irrigators how much they can pump without depleting the aquifer. The study, 13 years in the making, creates models of the Klamath Basin’s hydrology, showing irrigators can pump about 56,000 acre feet of water in an average year, about one-eighth of the Project’s annual demand.
Irrigators say the study will help them mitigate droughts. Water researchers say it is important science, revealing how the Basin works.
“The beauty of the model is it can give us some insights in how to manage the system in the long term,” said Marshall Gannett, a USGS hydrologist who has been studying the Basin’s groundwater since 1999.
Gannett hastens to point out the amount of water irrigators can sustainably pump will vary widely from year to year. When the aquifer is depleted from drought or previous groundwater pumping, irrigators won’t be able to pump as much.
The amount Project irrigators can sustainably pump is in addition to the groundwater already pumped by irrigators off the Project and for municipal drinking water, Gannett said.
Groundwater will be a key component to the On-Project Plan, a plan for how to manage irrigation water under the Klamath Basin Restoration Agreement, a controversial water settlement, Cannon said. The USGS study, he said, is critical to making sure groundwater is a viable resource in the long-term.
“It’s a means to ensure ... we’re not in a race to see who gets the last drop of groundwater,” Cannon said of the study.
Henley-area hay and potato farmer Ed Bair plans to use his groundwater well if there is a shortage of surface water this year. Pumping groundwater spares surface water for those who don’t have wells, he said.
Bair said the USGS study provides a good guideline for managing groundwater.
“If we manage it right, it can last us a long time,” he said. “If we don’t, it can be short lived.”
The study showed not only how much water can be pumped, but where the water comes from, Gannett said. Some worried that pumping groundwater would siphon creeks and springs, which provide water downriver for endangered fish, but it turns out the aquifer is largely recharged with irrigation water seeping into the ground, he said.
Another report from the USGS that puts the data into more realistic water management strategies could be released by the end of the year, Gannett said.
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