Wednesday, April 6, 2011

Cottonwoods out, water in

Water District 45 tree work changes Bellevue Triangle landscape

Express Staff Writer

Worker Dan Zortman uses a chainsaw last week to cut hanging limbs from cottonwood trees being hauled away south of Bellevue. Express photo by Roland Lane

More than one driver has lost a landmark this spring to irrigation ditch maintenance. Along stretches of state Highway 75 and Gannett Road south of Bellevue, thousands of cottonwood trees have been cut down and removed by Water District 45 as a water conservation measure.

In advance of surface-water irrigation season, this year, "the district," as the quasi-governmental agency is commonly called in legal documents, has been removing trees that have propagated along its nearly century-old irrigation ditches. The ditches branch out from a headgate on the Big Wood River in Bellevue.

Cottonwood trees have been identified as being very efficient vectors for evapo-transpiration of water, said District 45 Treasurer Pepin Corso-Harris, adding that construction of the ditches nearly a century ago provided new habitat for cottonwood trees. Beyond the complexities of meeting water demand, many neighbors of the Water District have voiced frustration at seeing familiar trees cut down.

"People look at me and go, 'You just hate trees,' Corso-Harris said in an interview at the headgate, where water typically enters the District 45 ditches sometime after April 15 each year.

Corso-Harris added that she and her husband have planted many trees on their own property and they know how long and how much work it takes to grow a tree.

"I understand how they feel," she said. "It's habitat. Cottonwoods are a block for noise, but they take an incredible amount of water and ruin the banks of the ditches."

Corso-Harris, who said she once loved bachelor buttons until they took over like a weed, is fond of saying, "I never met a cottonwood I didn't like, unless it's in the ditch."

The district has, most recently, been clearing cottonwood trees from the canals since 2005, Corso-Harris said, adding that there have been previous eradication campaigns. She said reaction to the work has been mixed, but it is being billed as a water conservation measure along ditches that have very porous beds and at a time when water scarcity is a growing issue in a basin where water rights are over-allocated, according to the Idaho Department of Water Resources' Snake River Basin Adjudication, an ongoing water rights clarification process.

The ditch-clearing budget set by the district is about $20,000 this year.

Much of the slash from the District 45 work is being taken to the Diamond Dragon Ranch on the Big Wood River, where it is being used to rebuild stream banks by planting huge cottonwood rootballs to jumpstart cottonwoods growing along the stream.

"The work will help create eddies, shade and better fish habitat," Corso-Harris said. "Even with all that has been trucked down there, we could not fill their quota. As I understand it, they are now speaking with the Baseline Canal Co. to see if they might be clearing any trees from their banks."

Though the ditches were initially built with some federal funds in 1915, ongoing operation and maintenance of the ditch easements are funded entirely by those who maintain surface water rights associated with the unlined ditches, Corso-Harris said.

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