Download DCPA-QandA for Group Bs and Private Wells

DCPA Acid Metabolites in Drinking Water / Group Bs and Private Wells near Hill Top Acres
Q & A for use by WWCHD in answering questions from Group Bs and private well owners
What Is DCPA?

DCPA, commonly known by the trade name Dacthal, is an herbicide used to control grasses
and weeds. It is registered for use in Washington and Oregon.
How Can DCPA Get Into My Drinking Water?

After DCPA is applied, it breaks down into two other products called metabolites. These get
into groundwater when fields are irrigated or it rains. Concentrations of DCPA acid
metabolites detected in drinking water may vary during the year due to chemical breakdown,
soil permeability, precipitation, irrigation activities, and groundwater changes.
Are There DCPA Acid Metabolites In My Drinking Water?

The only way to know if DCPA acid metabolites are in your drinking water is to sample
your water and send the sample to a laboratory for analysis.

Information about laboratories that can test water samples for DCPA (Dacthal) can be found
at the Washington Department of Ecology’s Laboratory Search Website:
https://fortress.wa.gov/ecy/laboratorysearch/.

Consult the lab for instructions about proper collection and handling of water samples and
information about cost of laboratory analysis.
What if DCPA Acid Metabolites are detected in My Drinking Water?

If DCPA is detected in your drinking water, we recommend continued annual testing to
monitor whether the detections are increasing or decreasing over time.

The Environmental Protection Agency’s (EPA) lifetime Health Advisory Level (HAL) for
DCPA acid metabolites is 70 micrograms per liter (µg/L). The HAL is the concentration of
a contaminant in drinking water that is not expected to cause any adverse non-carcinogenic
effects over a lifetime of exposure (for example, an adult person who consumes two liters of
water per day for 70 years).

If you have detections near the HAL, you may wish to test your water more frequently (for
example, 2 or 4 times per year).

For water systems with detections near the HAL, the Washington Department of Health is
not recommending at this time that customers should take action such as purchasing bottled
water or installing home treatment units.

However, there would be increased concern if there were
o a single very high detection of DCPA (significantly above the HAL), or
o persistent (over many years) elevated levels (above the HAL) of DCPA in your
drinking water.
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What’s being done to address this problem?

Washington State Department of Agriculture (WSDA) is implementing its Water
Quality Pesticide Management Strategy and conducting education and response
actions.

WSDA and Oregon Departments of Agriculture and Environmental Quality (ODA
and ODEQ) staff are working together to assess DCPA uses in the area south of
Walla Walla and conduct well monitoring in 2016 and 2017.

WSDA is coordinating with the manufacturer of DCPA, area dealers, and applicators
to assess potential DCPA label changes and/or restrictions in Washington.

EPA Region 10 staff in Seattle are coordinating with, and assisting, WSDA, ODA,
ODEQ, and DOH in the activities described above.
Can DCPA Be Removed From My Drinking Water?

Yes. DCPA acid metabolite concentrations in your water may be reduced or potentially
eliminated using treatment units that use reverse osmosis. If you wish to get more
information about water treatment, we recommend consulting with a home water treatment
expert or the manufacturer of the unit you would like to use. An expert can explain how the
treatment system should be used in your home, its effectiveness at removing DCPA acid
metabolites, and costs associated with operating and maintaining the system correctly.

Additional information from the National Sanitation Foundation about drinking water
treatment units is available on the internet at info.nsf.org/Certified/DWTU/.
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