Water deal may save science treasure chest

Settlement may prevent landslides, save Idaho fossils

Christopher Smith, Associated Press

Saturday, October 7, 2006

HAGERMAN, Idaho - For decades, paleontologists have watched the richest deposit of fossils from the prehistoric period known as the Pliocene Epoch crushed to dust by frequent landslides crashing off the face of 600-foot-high bluffs along Idaho's Snake River.

The Hagerman Fossil Beds National Monument - site of the discovery of 43 species, including eight found nowhere else - has become so unstable because of landslides that more than 10 percent of the site, some 4,400 acres, is permanently closed.

But recently, scientists have begun to believe the buried treasures of ancient eons won't continually be lost in a pile of rubble.

For the past two summers, huge electric pumps that normally suck thousands of gallons of water from the adjacent Snake River and pump it to the top of the bluffs onto a plateau of farm fields have been silent. One of the fields is planted with dryland grain crops, but the rest lie fallow. The irrigation district that ran the pumps sold its water rights to the state for $24 million in 2005 as part of the settlement of one of the largest water rights claims in the West.

That agreement, known as the Snake River Basin Adjudication, was signed into law by President Bush in December 2004. It provides for the state, federal government and Nez Perce American Indian tribe to exchange land and money in return for the tribe's relinquishment of claims to nearly all the water in the Snake River basin.

The deal was never intended to help preserve a prehistoric trove of equine, mastodon, saber-toothed cat, fish, snake and waterfowl fossils. But by ending irrigation at the Bell Rapids project on the Bruneau Plateau above the fossil beds, monument officials believe the rate of landslides will decline significantly.

"If you would have asked me a few years ago if I could wave a magic wand and change anything to protect fossils here long-term, I would have said, 'Quit pumping the water,"' said Neil King, superintendent of the monument. "The Snake River agreement made that happen and that was a great deal for the fossils, but there was an impact. There's 18,000 acres up there that were once in high production and now they're gone, along with about 300 jobs." Greg Brown, president of Bell Rapids Irrigation Co., said farmers never agreed with monument studies that concluded their crop sprinkling was triggering the landslides.

"We did our own studies, and it showed just the opposite," said Brown, who sold all his cropland on the plateau after the water rights settlement and no longer farms. "To say we were the cause just doesn't hold up."

When Congress established the monument in 1988, lawmakers determined irrigated farming was a compatible use with the preservation of paleontological resources in the adjacent fossil beds. The beds, laden with fossils of animals that lived at least 5 million years ago, were exposed 15,000 years ago when the Bonneville Flood cut the valley through which the Snake River now flows.

Park Service studies dating back to 1984 found that water pumped into unlined irrigation canals on the plateau drains into the loose sediments of the fossil beds until it reaches an impermeable layer of rock. It then flows horizontally underground until it seeps out the 45-degree face of the bluffs along the river canyon, creating so-called "perched aquifers." "When that happens," said Phil Gensler, the park's paleontologist, "it's like grease between the sediment layers." There have been 10 major landslides in the monument since 1979.

A 1987 slide from the bluffs destroyed a $1 million irrigation pumping plant along the river. The 1993 Bliss landslide completely blocked off the Snake River, temporarily forming a lake. Today, along the edge of the plateau overlooking the river, giant cracks appear in the earth.

And when the face gives way, the fossilized record buried in the bluffs is lost.

"We have 600 feet of stratigraphy here that represents about 1 million years in time, and each layer is like a page in a book," Gensler said. "When all those fossils come down, even if you're lucky enough to find them intact, they've lost all their provenance; we don't know exactly what page they came off of, whether it was the beginning or the end of the book." Brown maintains that the perched aquifers were on the bluffs long before irrigation began on the plateau in 1970. And he believes irrigated farming may one day return to the plateau.

"We have dismantled some of pumps and removed a lot of main lines, but there's always a possibility that land could be put back into production if conditions and technology improve," he said.

But the Park Service is operating under the assumption that the pumps are gone for good. A National Park Service hydrologist who spent the past 10 years studying ways to reduce the seepage of irrigation runoff and better predict landslides recently transferred to another federal agency. His expertise is no longer needed at the monument, King said.

Although irrigation of the plateau ended two years ago, monitoring wells have not recorded any significant change in the rate of water flowing through the underground layers. That may take 10 to 15 years, officials estimate.

"You've got to remember it took a long time for these unnatural aquifers to develop and it took a lot of water to build up in the ground to create these perched aquifers," Gensler said. "It's probably going to take a long time for that water to drain out."