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Department of Ecology News Release - December 9, 2004
04-226
YAKIMA - A water quality study that showed concentrations of the pesticide DDT were entering Mission Creek from Yaksum Creek near Cashmere piqued the curiosity of local horticulturalist Bob Gix and got him to investigating.
The study, posted this month by the Washington Department of Ecology, concluded that residual DDT held in the soil along the stream bank was eroding into Yaksum Creek and feeding into Mission Creek.
Study samples were taken in 2000 and 2003 as part of a statewide initiative to identify polluted water bodies that need cleaning up.
Gix, a participant in local watershed planning, thought the conclusions drawn did not track with local experience and observation.
"The report led me to believe I would see eroding banks and obvious soil moving in Yaksum Creek during the irrigating season," Gix said. "Yet living and working in the area I could not recall having observed either of these events."
Looking at a "suspect" irrigation overflow pipe did not reveal the cut bank and raw exposed soil that the report led Gix to believe was there. He then tracked down Scott McManus, who oversees the Yaksum Creek irrigation system. Recently, Gix visited with McManus and learned that during the late fall of 2003 the users discovered their overflow pipe had become blocked with a cottonwood root ball.
"When the users shut off their water during harvest the overflow now had no pipe to travel in, so part of the hillside eroded on the water's downhill trip to Yaksum Creek," explained Gix.
The Yaksum Creek irrigators and Chelan County Public Works repaired the damaged section of pipe and improved the overflow delivery to Yaksum Creek to help prevent erosion during the fall of 2003.
With a little sleuthing, Gix believes he has discovered the probable cause of the spike in DDT that entered Yaksum Creek during 2004.
"A pipe had clogged and water had eroded soil that entered Yaksum Creek," he said. "Once the soil was in the creek, the natural sediment transport mechanisms moved the soils down the watershed."
The study suggests that by preventing bank erosion, the amount of DDT in the water column could be significantly reduced. Continued monitoring of cleanup efforts and water quality are also recommended.
"These were very good common sense observations," said Mike Kaputa, chairman of the Wenatchee Watershed Planning Unit. "Yet in this case it took local involvement to reveal the cause of the spikes in sampling levels during the 2004 season. This story highlights the value of local participation in the watershed planning process."
Although banned 30 years ago, DDT continues to be present in relatively high concentrations in the soils. DDT is regularly found in waters near fruit orchards as it was widely used to control insect pests. This material was also used by local mosquito control districts and in some forest practices. DDT persists in the environment for decades.
People interested in more information on the watershed planning and water quality cleanup efforts may contact Mike Rickel at 509-664-0268. More information is available on-line at http://www.co.chelan.wa.us/nr/nr_wen_watershed.htm . (Note: Link updated Oct. 3, 2005.)
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Media contact: Joye Redfield-Wilder, public information manager, (509) 575-2610
Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html.
