Aquifer recharging can help stanch drought

Oregon is successfully capturing runoff to underground storage.

  • The infiltration gallery at the Barrett Aquifer Recharge site in Oregon. The perforated pipes are later buried.

    Courtesy Walla Walla Basin Watershed Council
 

When spring floods devastated river towns and farmlands along the Missouri River in 1927, Congress ordered the U.S. Army Corps of Engineers to prepare a comprehensive hydrological report on the million-square-mile Missouri River Basin. The Corps' engineers spent the next five years preparing a bells-and-whistles study, from Fort Peck, Montana, to St. Charles, Missouri.  It's a thing of beauty, this opus, with foldout maps drawn from geologic surveys of every bend, island and sandbar in the river. 

Privately, the agency viewed this enterprise as an opportunity to slam the door on all those hair-brained irrigation and flood-control schemes forever being promoted by dry-land farmers and politicians. The Corps had learned its lessons on that "mad elephant of a river" the hard way: rescuing stranded paddle wheelers year after year. By 1927, it had other rivers to tame -- let the Big Muddy run wild.     

In February 1934, the Corps' director, Gen. Lytle Brown, presented the 1,245-page masterpiece to Congress with a stern warning: Don't even think about building flood-control dams on the Missouri River above Sioux City, Iowa. His chief concern was that the river's perennial “siltation problems” would clog hydro-turbines and keep dredges working in perpetuity at a cost of billions of dollars. Nonetheless, after the 1943 floods devastated Iowa and Nebraska, Congress demanded action and approved five major dams on the main stem of the river.

But, as Lytle warned, siltation remains a major problem to this day, and the biggest and most devastating consequence was one that never occurred to agency engineers. When silt settled behind dams along 2,500 miles of river-bottom, it not only clogged hydro-turbines and kept dredges running, it also formed an impenetrable blanket of muck that stopped the river from recharging one of our nation's most important water resources, the Ogallala aquifer.  

When you think of the Ogallala aquifer - stretching from southern Canada to northern Texas - imagine an invisible ocean. Rivers once recharged it as well as other aquifers. Now, “silted-in” rivers can't do the job, and aquifers are drying up across the West. Fast.

"The Western Hemisphere is experiencing a drought of crisis proportions," writes Science magazine's editor-in-chief, Marcia McNutt, in the September 2014 issue.  She notes that crops are failing across the Americas, millions of Central Americans who depend on rainfall to grow food are facing starvation, and ships using the Panama Canal will soon have to lighten their loads to keep from running aground (thereby increasing the prices of field-to-market goods grown in the American West).  At home, drought is rapidly spreading to the very farm and ranch lands that produce much of the nation's fruits, vegetables and beef.  

To keep up with demand, growers have been doing what they always do in low water years: They make up the deficit by drawing from groundwater aquifers.  The groundwater drawdown in California's Central Valley between 2003 and 2012, for example, was equivalent to the entire storage capacity of Lake Mead, the nation’s largest reservoir. 

Alarmed hydrologists state the obvious: This trend is not sustainable. Even when the rains return, aquifers will be severely depleted for decades to come. It takes decades for a melted snowflake to percolate down to an aquifer.

Faced with this daunting problem in parts of their own state, hydrologists from Oregon State University and the Walla Walla Basin Watershed Council came up with a remarkable solution in 2004; it’s even relatively cheap, at just 1 percent the cost of a conventional dam, reservoir and distribution system.

The solution is something called “infiltration galleries.” Hydrologist Bob Bower convinced farmers and skeptics at Oregon's water and environment agencies that a series of these large, swimming pool-sized basins could collect the surplus winter flow from the Milton-Freewater River in central Oregon, use it to recharge the aquifer through percolation, and, as a bonus, also enhance the river's natural habitat.

"The infiltration galleries succeeded beyond our wildest expectations," says John Selker, one of the scientists working on the project.  "What we realized was, ‘Wait a minute, we've got all this surplus winter flow that runs out to the sea.  Why don't we recharge the aquifer with a portion of that surplus and use the aquifer as a storage basin? That way we know exactly how much water has been returned to the aquifer and is available for summer use.’"

The infiltration galleries have been so successful in Oregon that another eight have been built, two more are under construction, and five more are planned.  During the 2013 season, they “infiltrated,” or stored, 1.93 billion gallons of surplus winter-flow in deplete aquifers, at a tiny fraction of what it would have cost to build a catchment reservoir and distribution system.

"At a time when groundwater resources are vanishing at an alarming rate across the West," says Selker, "recharging our vast underground storehouses with 'winter-flow' is an idea whose time has clearly come.”

Paul VanDevelder is a contributor to Writers on the Range, a column service of High Country News. He lives in Oregon and is the author of Savages and Scoundrels: The Untold Story of America’s Road to Empire through Indian Territory.

Note: the opinions expressed in this column are those of the writer and do not necessarily reflect those of High Country News, its board or staff. If you'd like to share an opinion piece of your own, please write Betsy Marston at betsym@hcn.org.