RREA
University of California
RREA

Wastewater

RON BOYD-SNEE : POPLAR PLANTATIONS

A one-day workshop for water users, treatment officials and rate payers will be held from 8 a.m. to 5 p.m. on Wednesday, August 16, 2006, at the Sheriff’s Posse Grounds in Jamestown. The workshop will focus on growing crops with treated municipal wastewater. For more information, contact Jay Norton, UC Cooperative Extension Tuolumne County Director & Farm Advisor -- JNorton@co.tuolumne.ca.us or (209) 533-5686.

Jamestown, CA. -- As more people move into Tuolumne County and other Sierra Nevada counties, two water problems are surfacing:

-- a limited supply of fresh water
-- an oversupply of treated wastewater

The traditional approach to these problems – building more reservoirs and treatment plants – costs too much. Jamestown – and other small communities in the Sierra foothills -- isn’t San Francisco: it doesn’t have a bazillion people to fork over taxes to support high-dollar tertiary treatment plants or a big ocean outside its back door in which to dump the cleaned wastewater, which has to be diluted in a 20 to 1 ratio.

In addition, says Ron Boyd-Snee, operations manager at the Jamestown Sanitary District, this traditional approach just creates the need for more reservoirs and more treatment plants. In a word, it’s: unsustainable.

In the spirit of “small is beautiful”, the cheap, sustainable answer to this dilemma is a tree. The big, leafy, fast-growing, water-loving poplar tree.

With the flexibility afforded to small organizations, Jamestown Sanitary District, which serves 1,600 people in Jamestown, Ca., has been running an experiment for the last eight years. With help from scientists at the University of California Cooperative Extension, they’ve been growing a 12-acre poplar tree plantation on once-bare land outside town.

The results? Well, Boyd-Snee doesn’t want to sound too over-the-top, but from all indications, poplars look like a pretty good deal. “We think there’s a huge potential for California, especially the Central Valley, because of the climate,” he says. “You can use them for saw logs, as nursery stock, you can cut and relocate them. You can plant trees to get carbon credits. There’s a huge potential for biomass and the opportunity to get another credit for a renewable resource.”

Poplar trees, part of the willow family, include cottonwoods and aspens. They belong to the genus Populus. For the last 30 years, researchers have been developing hybrid poplars that will grow better in certain climates, or to be more drought- or pollution tolerant, disease-resistant or to strengthen other properties, such as for pulp or saw logs.

Generally speaking, poplars love water produced by secondary treatment plants – which is all communities like Jamestown can afford. This is water that can’t be used on food crops.

During the winter, the district collects and stores wastewater in a large lake. Once the rains stop, they use the water to irrigate the poplars. Each tree can suck up 10 to 20 gallons of water each day. The trees can grow 10 feet a year. The eight-year-old trees are now 50 feet tall. The trees seem to thrive on the extra nutrients abundant in water from secondary treatment plants, such as nitrogen, and the scientific literature supports that, says Boyd-Snee. “However, we’re still in the study portion to make sure that’s the case,” he says.

The district tried two different irrigation methods – flooding (land wasn’t flat enough), sprinklers (too much land lost to setback and weeds choked the sprinklers) – before settling on a drip system. And it’s experimenting with 35 different types of clones, to identify those that are most suitable for the area.

The trees live for about 40 years. They can be harvested for paper, for fuel and for saw logs. “We actually had a friend build us a little box, just to show that you can build stuff,” says Boyd-Snee. “It’s an odorless wood. It’s good for shipping. You can put pharmaceuticals, wines, candy in those boxes.”

And dig this: you can slice off a four-year old tree that stands 30 to 40 feet tall at the base with a chain saw and plant the pole in the ground. The result? An instant tree that grow leaves bigger than King Kong’s head.

If public utilities and landowners grew plantations of poplar trees, says Boyd-Snee, they could eliminate a pollution problem, conserve fresh water, and provide economic opportunities. Cattle ranchers who now use their wastewater to irrigate pastures could grow poplars and have another source of income. The trees, which are very resistant to pollutants, have been used to take up contaminated water, to arrest plumes emanating from gas stations, and have been planted around dairies to take up polluted water from feedlots. They can also be planted as an intercrop – with hay or other forage.

Poplars are well, popular, in many parts of the globe. In the United States, about 50,000 acres of poplar trees are in commercial production for wood products, quality paper, small furniture, and pulp. Canada, Europe, and Chile also boast productive poplar plantations. The U.S. Department of Energy is testing poplars as a source of ethanol, and the National Carbon Offset Coalition is looking into poplar trees’ ability to sequester carbon dioxide.

As for California ranchers and farmers, poplars can solve problems and provide profits, says Boyd-Snee. “I think it’s a real win-win situation,” he says. “But you gotta prove it to people, and you gotta show them that it’s economically reasonable to do, and I think we’re about there.”

-- by Jane Ellen Stevens
April 2006

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