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LeMasters, Gary S.; Doyle, Douglas J. / Grade A dairy farm well water quality survey
[DNR-058] (1989)

Abstract,   pp. i-ii PDF (319.7 KB)


Page i

ABSTRACT
The Wisconsin Department of Agriculture,
Trade   and    Consumer    Protection
(WDATCP) estimated the proportion of
wells on Grade A dairy farms that contain
detectable levels of pesticides and nitrate-
nitrogen (NO3-N). A random sample of
550 farms was drawn from the population
of 23,543 Grade A dairy farms. These
farms were chosen because WDATCP has
authority to collect water samples as part
of its inspection program and because
sampling this population should provide a
meaningful measure of the presence of
pesticides  in  groundwater  in  rural
Wisconsin.
Water samples were actually collected
from 534 of the 550 farms and analyzed
for 44 compounds including 10 of the
herbicides and 4 of the insecticides most
commonly used in Wisconsin. One or
more herbicides were detected in 71 wells.
Sixty-four (64) of these contained atrazine
alone, 3 contained alachlor (LassoO) alone,
1 contained metribuzin (SencorĀ®) alone,
1 contained atrazine and alachlor, 1
contained  atrazine  and  metolachlor
(DualĀ®), and 1 contained alachlor and
metribuzin. The maximum concentration
of atrazine was 19.4 micrograms per liter
(ug/l) with a median of 0.45 ug/1. The
Enforcement Standard for atrazine of 3.5
ug/l was exceeded in 3 wells.    The
maximum alachlor concentration was 5.9
ug/l with a median of 0.7 ug/l. The
Enforcement Standard for alachlor of 0.5
ug/l was exceeded in all 5 wells where it
was detected.
The proportion of wells on Grade A dairy
farms that contain detectable levels of
pesticides is estimated with 95 percent
confidence to be between 10 and 16
percent.   The   proportion  of wells
containing detectable (at or above 0.15
ug/l) levels of atrazine is estimated to be
between 9 and 15 percent. Between 5 and
9 percent of the wells contain atrazine
above the Preventive Action Limit of 0.35
ug/l.  There were insufficient data to
estimate the proportion of wells containing
any pesticide above an Enforcement
Standard.
The proportion of wells containing NO,-
N is estimated to be between 61 and 69
percent.   The   proportion  of wells
containing NO3-N above the'Enforcement
Standard of 10 mg/l is estimated to be
between 7 and 13 percent.
The survey was not designed to determine
whether the pesticide detections resulted
from pesticide application according to
label directions or from mishandling.
However, many farm operators whose
wells contained a pesticide above the
Preventive Action Limit were interviewed
about the way they handle and apply
practices. From these interviews it seems
that while most of the farm operators
handle  these   compounds   carefully,
improper disposal of pesticide rinsate and
empty containers may be a problem
source. Farm operators also need better
information about the construction of their
well and the relationship between activities
at the surface and groundwater quality.
Finally, the regulatory community needs to
assist  the   farm   community   in
understanding the health implications of
Wisconsin's groundwater standards.


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