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Friday, Aug. 22, 2008
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Franklin County slide may be result of oversaturated land
By John Trumbo, Herald staff writer
The collapse of a cliff along the Franklin County side of the Columbia River this week could be an act of God, but also may be the result of irrigation water loading the ground beyond its saturation point.
The water table beneath agricultural land in the South Columbia Irrigation District has "come up substantially" over the years, said Mike Hepp, who is a water quality specialist for the Washington Department of Fish and Wildlife.
Hepp said landslides along the river have been common for years, but not as large and as sudden as the one Wednesday in the Sagemoor Road area off Cottonwood Drive that dumped tons of white soil into the river current.
Hepp said researchers have been aware of the potential for landslides triggered by ground water along the Columbia River since before 1988. That was when the Franklin County Conservation District published a report noting ground water in the region had come up as much as 300 feet since the 1940s, when the federal government built an extensive system of unlined canals to distributed irrigation water.
"And it has come up substantially since then. The question is, is that affecting the (clay) cliffs?" he said.
Hepp said he plans to meet with representatives of the Franklin County Conservation District to determine the source of water that appears to be making the cliffs alongside the river unstable.
"Why did it slide now? Is someone doing something different? If the water is coming from (unlined) canals, then it probably can be fixed," Hepp said.
The soil that reached the river from this landslide and created a large plume of silt for miles downriver may not be as bad for fish as some feared, Hepp said.
"There is a window when work can be done in the river when there is no harm to fish. I think this may have occurred in that window. We are early (before fish arrive)," he said.
Fall chinook salmon are making their way up the river now, but recent fish counts at dams downriver indicate few have made it this far.
The cliff where the slide broke loose this week is about 450 feet above the river, Hepp said. He said there are springs about 350 feet above the river that release underground flows into the soil, setting up the potential for the cliff to slip and slide.
"The question is what is feeding those springs?" Hepp said.
Farmer Alton Haymaker believes the answer is the network of unlined irrigation canals that lace hundreds of square miles of Franklin County.
Haymaker and his wife Joan have raised fruit and crops on their irrigated farm just east of the slide for decades. He came in 1941 and has seen several chunks of cliff fall away, but nothing the size of what occurred this week.
"This is a whole bluff. I was in awe at what I saw," he said.
Haymaker spent decades trying to convince federal authorities through the courts that water seeping from the unlined canals and reservoirs that are part of the Columbia Basin project has saturated the earth beneath his orchards.
Haymaker said overirrigating is not the problem. He said good farmers know that overwatering leaches their expensive fertilizers so deep they are not beneficial.
Haymaker insists the problem is what lies deeper. "This is what is causing wet ground. Water is meeting water and the salts are coming up," he said.
Joan Haymaker said their battle in federal court to stop the seepage failed to resolve the big issue, although the government agreed to line one of the ditches serving their land about seven years ago.
"It's too bad the U.S. Bureau of Reclamation didn't put the system in better than they did (50 years ago)," she said.
Mark Nielson, manager of the Franklin County Conservation District, said there's little his agency can do in response to this week's major land slump.
"We've tried to revegetate the area, but it is slumping too deep," he said.
Nielson said the 1988 report included findings from the U.S. Geologic Survey noting that 80 percent of the recharge to ground water in the region is coming from the system of unlined canals. That water enters a porous Ringold geologic formation -- a virtual conduit for the water to find its way to the vulnerable clay cliffs.
Nielson said "nothing has changed" in the past 20 years to prevent that water from taking down the cliffs, one slump at a time.
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