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Maps put basin's water, fertilizer in perspective
Geologic study changes thought on sources of irrigation, water quality

Capital Press by Lee Juillerat, 3/28/08

KLAMATH FALLS, Ore. - Recent geological studies in Southern Oregon's Klamath Basin may change some long-held assumptions about where to drill for water wells and the impacts of fertilizer and manure on Upper Klamath Lake's water quality.

The Oregon Department of Geology and Mineral Industries recently released two geologic maps of Klamath Falls and Klamath County's Upper Klamath Basin. Information-gathering for the maps began in 1998.

"It's very interesting to have an understanding of the geologic history, and it's different than what we thought," said Ian Nadin, the department's chief scientist.

Among key points:

n Most of the volcanic activity that has shaped the Upper Klamath Basin has occurred within the past 1 million to 2 million years. "If we go back 3 million years, (the terrain) was pretty much as flat as a pancake," Nadin said.

n The upper basin has 464 volcanoes, which range from massive mountains like Shasta and McLoughlin to small cinder cones.

n By identifying fault lines, which typically are sources of underground water, the probability of locating and drilling less expensive, high-volume water producing wells is improved.

n Many ridges and mountains previously thought to be lava flows that contain underground aquifers are actually thin layers of lava atop chalk rock and are not good prospects for drilling successful wells.

n Higher-than-normal naturally occurring levels of phosphorus are responsible for reducing water quality in Upper Klamath and other lakes. Ranchers and farmers who use fertilizers, as well as cattle manure, have historically been blamed for the unusually high phosphorus levels.

Nadin said the findings involving phosphorus are important because steps to reduce fertilizer or cattle grazing use could harm crop production and ranching while having little or no impact on improving water quality. Although the amount of naturally occurring phosphorus is small, 1 percent, he said the amount is 10 times higher than in other areas. Phosphorous is found in rocks, sediment and water from springs.

"Some of that impact of phosphorous is natural. If a large percentage is natural and farmers are not allowed to use phosphorous fertilizer, it could have no impact on the water quality but could be detrimental to farmers," Nadin said. "Changing when and how you till may have more impact than how and when you fertilize."
Phosphorous levels

Richard Roseburg, an associate professor at the Oregon State University Research and Extension Center in Klamath Falls, said he isn't surprised that new findings show phosphorous is naturally occurring in Upper Klamath Lake.

Roseburg said phosphorous is a major element that contributes to algae blooms in the lake and the Klamath River. When the blooms die, the decomposition process uses oxygen in water, which can result in fish die-offs.

He said studies have shown lake sediments are high in phosphorous and that other quantities come from springs in and outside the lake.

While phosphorus is used in some fertilizers for such row crops as potatoes, wheat and onions, he said "not very much of that tends to move out of the soil." Phosphorus is also found in cattle manure, but Roseburg said the amounts are generally not significant unless high quantities are deposited in moving streams.

Maps available

Copies of two geologic maps of Klamath Falls and the Upper Klamath Basin are available from the Oregon Department of Geology and Mineral Industries.

Geologic map GMS-118 was started primarily in response to the 1993 earthquakes that caused widespread damage to the Klamath County Courthouse, 16 other downtown Klamath Falls buildings and the neighboring region.

Open-File Report O-07-05 is a mapping project that began in support of GMS-118 and was expanded because of the basin's increased focus on water issues.

"This compilation of 47 different geologic maps provides critical information for understanding the groundwater resources and the connections between groundwater and surface water in the upper Klamath Basin," said Ian Madin, the department's chief scientist. "It also identifies hundreds of newly mapped volcanoes in the area that have erupted over the past few million years into an environment of giant lakes."

The two maps are available on CD-ROM for $10 each. Printed copies are $15 each. They are available from the Nature of the Northwest Information Center, 800 NE Oregon St., Suite 177, Portland, OR 97232; by calling (503) 872-2750; or online at www.naturenw.org.


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