DPR RELEASES ANNUAL REPORT ON
GROUND WATER TESTING FOR PESTICIDES
SACRAMENTO -- Cal/EPA's Department of Pesticide Regulation (DPR) today
released its annual 1994 report on the results of ground water testing for
pesticides.
The report, delivered to the Legislature this week, summarizes ground water
monitoring in 44 well sampling surveys submitted to DPR between July 1,
1993 through June 30, 1994. The monitoring was done by various government
agencies between 1986 through 1994. Among other provisions mandated by the
Pesticide Contamination Prevention Act of 1985 (AB 2021, Connelly),
government agencies that test well water for pesticide residues must report
the results to DPR, which is required to report annually on the previous
year's submissions.
"This reporting mechanism provides valuable information in that it helps
DPR and other agencies target further monitoring," said Paul Gosselin,
Assistant Director of DPR's Enforcement, Environmental Monitoring and Data
Management Division. "Although limited ground water data bases have been
compiled in at least nine other states, only California centralizes
monitoring results from all sampling agencies into a single collection
point, on an ongoing basis."
Altogether, samples were taken from 2,839 wells in 50 of California's 58
counties. Pesticide residues were detected and verified in 37 wells in ten
counties. Of the 37 wells, 20 were private drinking water wells, 13 were
public drinking water wells, two were non-drinking water wells, and the use
of two wells was unknown.
Most samples were analyzed for various numbers of chemicals. Overall, the
tests targeted a combined total of 114 pesticide active ingredients and
breakdown products. Of those, verified detections of six different
compounds were made. Five of the chemicals detected were herbicides --
atrazine, bromacil, diuron, prometon, and simazine. The sixth chemical was
an herbicide breakdown product (deisopropyl- atrazine). All have been
found in previous years.
Three herbicides were found for the first time in Yolo County (atrazine),
Stanislaus County (prometon), and Colusa County (simazine).
Routine agricultural use of currently registered pesticides was determined
to be the cause of pesticide residues found in ground water for the first
time in five counties: Colusa, San Joaquin, Solano, Yolo, and Merced.
Routine use was also determined to be the source of pesticides detected in
five counties where they had been found previously: Fresno, Glenn, Los
Angeles, Riverside, and Tulare.
DPR investigates all reported detections of pesticides currently registered
for agricultural or outdoor industrial or institutional use. The first
time a currently registered pesticide is detected in ground water, DPR
conducts an investigation to determine if the the source of the residue is
legal agricultural use. If it is determined that legal agricultural use is
the source, DPR establishes a pesticide management zone (PMZ) around the
location of the detection. A PMZ is a geographic surveying unit of
approximately one square mile in size, designating the area as sensitive to
ground water pollution. Once a PMZ is established, DPR initiates special
restrictions on the use of the detected chemical in the area.
"Even though this report is a valuable archival record, people should
realize it can't be used as a basis for making any determinations about
ground water in California," said Gosselin. "The data in the report is
comprised of results from studies designed and conducted by various
agencies and companies for different purposes, and with different methods.
This makes it difficult to use the data to make comparisons and draw
conclusions."
DPR in its investigations first attempts to verify the detection by
analyzing new samples from the positive wells. Nearby wells are also
tested to determine the extent of any contamination. If levels of
contamination found exceed those considered safe, the State Department of
Health Services may take immediate corrective action. In addition, DPR may
take action regardless of the level of contamination. Actions in the past
have included revocation of permits to use pesticides, modification of use
practices to prevent ground water contamination, or suspension of a
chemical's registration in California.
After a detection is verified, the investigation focuses on whether the
pesticide reached ground water because of routine agricultural use
(application to crops, for example). "Point" sources of pollution (such as
a pesticide spill into a well) are referred to the Water Board for further
action. Also referred to the State Water Resources Control Board for
further investigation are detections of pesticides registered for non-
agricultural uses or those no longer registered.
Factors that contribute to ground water contamination by pesticides include
amounts used and method of application, irrigation practices, the
physicochemical characteristics of the pesticide, soil type and climate.
"Regulation of pesticides to prevent residues from entering ground water
depends on scientific knowledge of how pesticides move to ground water,"
said Gosselin. "DPR environmental scientists are conducting field studies
on pesticide movement -- investigating contaminated wells, compiling
extensive data bases, and reviewing the work of other scientists -- to
better understand the factors contributing to ground water contamination by
pesticides. This information is being used to develop pesticide use
practices that will prevent ground water contamination by agricultural use
of pesticides."
Media Contact: Veda Federighi (916) 445-3974
Single copies of the report are available free from
Department of Pesticide Regulation
Environmental Monitoring and Pest Management Branch
1020 N Street Room 161
Sacramento CA 95814
(916) 324-4100
Electronic copies are not available, but you may request a copy by e-mail.
Send your name and address to cmiller@cdpr.ca.gov