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Environment | Water

How Drawing Down Rivers Can Impair Water Quality

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CHALLIS, Idaho — Rancher Ted O’Neal stands beside the banks of the Pahsimeroi River. He’d be just as dry standing in the middle of the riverbed.

To explain why the river is just a trickle, O’Neal describes what happens upstream every summer.

“We actually have to dam the Pahsimeroi River off to get our decreed rights filled at this time of the year,” the long-time rancher says.

O’Neal and other ranchers use heavy machinery to put dirt and rocks in the river’s path. The water is redirected to a ditch. Almost every drop is used to flood irrigate their land - all summer long.

Farming is the single biggest reason rivers are failing to meet the goals of the Clean Water Act. To find out why, I visited some of the farms and ranches scattered along the Pashimeroi Valley — a narrow seam carved into 50 miles of steep mountains. I discovered it isn’t so much what the valley’s cattle ranchers and alfalfa growers are putting into the water that leaves it impaired -– it’s what they’re taking out.

Jimmie Martiny’s family has worked the land here for four generations. He recalls stories his grandmother told — what it was like to hear the fish come up the river.

“She said it sounded like a herd of horses coming. Of course, that was a long time ago,” he says.

Jim Martiny
Jimmie Martiny

Martiny and his wife took over the operation in the 1960s. They didn’t see fish in their section of the Pahsimeroi until two years ago. The absence of salmon and steelhead was a sign that something wasn’t right.

Before this land was homesteaded in the 1800s, great volumes of water rushed down the Pahsimeroi River. Even after reaching this valley, the water from snowmelt and an underground aquifer ran cold. It was excellent habitat for salmon and steelhead.

When valleys like the Pahsimeroi were claimed for agriculture, trees along the streams and rivers were taken out. That made more land available but removed natural shade that kept the water cool. After farmers channel water out, the remaining stream runs shallow and warm.

Temperature is a big reason sections of the Pahsimeroi River are now considered “impaired” under the standards of the Clean Water Act. It’s the same story throughout the Pacific Northwest, ranging from southern Oregon’s small Bear Creek to the mighty Columbia River.

Joe DeHerrera is a biologist with the Bonneville Power Administration. The agency started monitoring water temperature in the Pahsimeroi and nearby Lemhi watersheds in 2008. It’s part of the BPA’s effort to improve habitat for salmon.

“They don’t do well when the temperature gets a little warmer. So it’s nice to know in the Lemhi and Pahsimeroi where that coldest water is, how to protect it, how to maybe turn the warmer reaches of water into cooler water,” he says.

The U.S. Environmental Protection Agency says trout, salmon and other cold-water fish need temperatures no higher than 68 degrees. The Idaho Department of Environmental Quality disputes this, saying these fish can survive in warmer water.

In any case, scientists agree that when water gets too warm, it’s bad for cold-water fish. It has less dissolved oxygen the fish need to breath. The temperature also causes the fish to burn up valuable energy.

To lower water temperature, some farmers are getting help switching to new ways of irrigating their crops. Instead of flooding their land, farmers are using pivot sprinklers. Sprinklers use less water. But they also have expensive up-front costs.

Pivot 2
Pivot head irrigation

Fifth-generation rancher Jimmy Dowton, Sr. says that was a big factor for him.

“As a rancher, I can’t afford to go in here and put them kind of system in because you are talking several hundred thousand dollars,” he says.

Dowton turned down several offers to help partially fund a pivot sprinkler system. He knew he couldn’t cover even part of the cost. So he stuck with flood irrigating.

“If you sit on the fence, you are gonna rip your crotch out,” he says. “But if you progress – get off to the right side, you’re going to keep a-going…but you can’t straddle the fence.”

Dowton jumped from one side of the fence to the other when his soil and water conservation district got money from the BPA to pay for the entire pivot irrigation system on his farm.

Remember Ted O’Neal, the rancher who’s been blocking off the Pahsimeroi River to divert water to his fields?

He’s applying for help to get the same water-saving irrigation system Dowton is using. If it all works out, O’Neal will still get what he needs, while leaving enough cold flows for fish.

“It would tickle me to death to see water in this river year around,” he says. “That would be a big plus to everybody including myself.”

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