April 8, 2003
Contact: Robert Lowery (509-963-1487/fax 509-963-2301/e-mail: loweryr@cwu.edu)
ELLENSBURG, Wash. - The impact of logging appears to have longer,
though possibly less critical consequences than some researchers had
thought, for forest water quality. That’s the conclusion of a study
conducted by Central Washington University senior Angela Diefenbach of
11 different deforested, re-growth and old growth areas in the Salmon
la Sac area in central Washington.
“I found that the effects of deforestation last a lot longer
than I thought, based on articles I had read,” she says. “These
articles indicated that the water quality changes lasted between two
and five years. Some of the areas that I studied were replanted 10 to
15 years ago and still showed chemical differences from areas in old
growth forest.”
Diefenbach looked at stream water chemistry to determine
major and trace element concentrations. There was an increase in the
concentrations of both major and trace elements in streams adjacent to
replanted areas as compared to others near deforested or old growth
corridors.
“When a forest is first clear felled you lose the top soil,”
she notes. “That makes erosion a lot easier, which means a loss of
nutrients which are washed away from the soils.”
The most pronounced increases in measured concentrations in
the waters were found in sodium, calcium, magnesium, barium, strontium,
aluminum and arsenic. The high concentration of arsenic wasn’t
expected.
“I found two re-growth streams that had up to eight parts per
billion of arsenic,” Diefenbach says. “That seems like a really minute
amount. But, the EPA (Environmental Protection Agency) standards limit
arsenic to below 10 parts per billion for drinking water, so these
streams were really close to being considered contaminated.”
It’s thought that the arsenic level increase may be due to the
weathering of a unique rock type found in the area and not necessarily
from mining done in the region.
“I was taking samples upstream of any area known to have
historical mines,” Diefenbach points out. “More study would have to be
done to determine the exact cause of the higher arsenic concentrations.”
The good news is, while longer in scope, the effects on water quality
are not necessarily cause for concern.
“I also took samples from the two major rivers, the Waptus
and Cle Elum,” Diefenbach adds. “By doing that, I was trying to get an
idea of how it all mixes together, after all the streams go in there.
Those rivers had really low concentrations of elements. So, their
chemistry is not heavily influenced by these regrowth areas.”
Diefenbach’s research, based on her interest in environmental
science, was conducted through the CWU McNair Scholars Program, which
helps fund eight-week summer research internships directed by faculty
mentors, in Diefenbach’s case that was Dr. Carey Gazis, CWU geological
sciences professor.
“Angie is an energetic researcher,” Gazis says. “She came up with
some interesting and unexpected results that I would like to follow up
on with future undergraduate researchers.”
The McNair program encourages students from low-income,
first-generation college backgrounds, or students from groups
underrepresented in fields of graduate study, to pursue advanced
academic degrees.
Funded by the U.S. Department of Education and CWU, it’s
named in honor of astronaut Dr. Ronald E. McNair, who died in the 1986
space shuttle “Challenger” explosion.
A 1999 graduate of Omak High School, Diefenbach, 22, will
graduate with her bachelor of science degree in geological sciences in
June 2004. She plans to attend graduate school, with a long-range goal
of becoming a college geology professor.
