Atrazine found in lakes far from farm
The herbicide is showing up at low levels, including in the BWCA, apparently carried by wind
By DAVID SHAFFER, Star Tribune
Last update: September 21, 2008 - 11:20 PM
re: Fishing Vacation Cancelled
Did you happen to read the article? It suggested it was carried in the air and could even have
come from other states. So pick another … read more state to fish and good luck. In fact if your
looking for an untouched and completely clean and pristine lake, your best bet would be another
planet. You must have your finger near the panic button all day long.
Graphic: Atrazine in Minnesota lakes
The widely used weed-killer atrazine is showing up in pristine lakes in northern Minnesota far
from farm country, and scientists believe the chemical is falling out of the sky.
In the first statewide study of pesticides in Minnesota lakes, government scientists discovered
small amounts of atrazine in nine out of 10 lakes sampled, including some in or near the
Boundary Waters Canoe Area Wilderness.
"To some people, it is a bit of a surprise, but the concentrations are low, very low," said Steven
Heiskary, a research scientist with the Minnesota Pollution Control Agency (MPCA).
The study shows that pesticides have joined the list of unwanted substances, such as mercury and
acid rain pollutants, that are spread vast distances by wind and rain to some of the wildest places
in the state.
The tests in 2007 of 53 lakes by the MPCA and the state Agriculture Department also found that
17 lakes contained breakdown chemicals from three other agricultural herbicides. The results
were published in a statewide pesticide monitoring report in August and will be presented at an
Six of the 46 lakes containing atrazine are in or near the BWCA, including two trout lakes in St.
Louis and Cook counties. Trout lakes are among the state's highest-quality waters.
The only urban lake tested, Nokomis in Minneapolis, also had trace amounts of atrazine.
The concentrations, in parts per trillion, are far below levels considered to be a risk to people,
plants or animals, researchers and others said. The maximum level for atrazine in waterways is
10 parts per billion. No such standard exist for herbicide breakdown products.
Atrazine, used mainly to control weeds in cornfields, is one of the most widely applied
herbicides in North America. When it drains from farmland, it can end up in groundwater and
Bill VanRyswyk, an Agriculture Department hydrologist who worked on the lake study, said
some of the tested lakes probably got herbicides from runoff. Yet the northern lakes that tested
positive for atrazine are nowhere near farms, he said. The likely explanation is that atrazine and
other herbicides are spread through the atmosphere.
Pesticides get into the air when they're applied or when wind blows dust from treated fields,
VanRyswyk said. Studies by other researchers suggest the chemicals can be transported long
distances and fall to earth as dust or in rain, he said.
"So it may well be coming in from out of state for those northern lakes," VanRys- wyk said.
He said additional lakes are being tested this year, and state agencies hope to test the original 53
lakes every few years to measure trends in concentrations.
Some Minnesota legislators also have worried about the herbicide, but efforts to pass tougher
state regulations failed in the legislature last year.
Atrazine has been controversial because some research has linked it to extra legs and other
deformities in frogs. An Environmental Protection Agency science panel is reviewing the
evidence. Syngenta, which manufactures atrazine, denies a connection. The frog deformities
were discovered by Minnesota schoolchildren in 1995.
In a statement, Syngenta spokeswoman Sherry Ford said the vast majority of atrazine results
were close to the limit of detection, and don't approach any health-based or ecological-based
water quality standard.
"These detections are due to technological advances which increasingly allow laboratories to
detect substances at levels so low they have no relevance to human or ecological health," Ford
It's the spread rather than the strength of the herbicides that worries Samuel Yamin, a public
health scientist for the St. Paul-based environmental group, the Minnesota Center for
"The fact that these chemicals are basically everywhere in the water resources is itself a concern
even if the levels in each one are not pushing the health benchmarks," Yamin said.
David Shaffer • 612-673-7090