Trees are very big drinkers

I live on a hillside on the east side of the valley. For several years, a half-dozen or so mature, 30-foot evergreens lined the side of my driveway. They were removed about five years ago and the past couple of years I've noticed continual standing water even during the late summer. Is it possible the trees absorbed all that water in the past?

— Karl J., via email

We can't say you're barking up the wrong tree, Karl.

We consulted our local tree guru, Max Bennett, Oregon State University Extension forestry agent, and he told us that indeed trees are very voracious drinkers.

"Trees are sort of like water pumps," Bennett said. "In the process of photosynthesizing and evapotranspiration — where the tree is basically growing — they use up a lot of water."

While it's not a common situation, Bennett says he's seen water tables rise in other parts of the state when trees have been removed. Soil type comes into play as well.

"There are some soils that are more sandy, very well-drained and porous, and others that are heavier in clay, and because of that, drainage takes longer," Bennett said. "Then there are impervious soil layers where water drains slowly or not at all."

Road building also could be a contributor to soil compaction, which could contribute to rising water tables as well.

"It's not all about trees, but it's possible the trees had an effect," Bennett said. "A larger tree can transpire hundreds of gallons in a day."

Send questions to "Since You Asked," Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by email to

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