Analysis of DEQ and DHS Pesticide Data in Oregon

December 2009

• LASAR returned over 120,000 records for the 187 pesticides evaluated in this analysis.  

Pesticides were detected in ~4,300 samples.  SDWIS had pesticides detected 67 times at 30

public water systems.  Sample dates for the LASAR/SDWIS detections were from 1982 to 2009. It

is important to note that the detection limits were fairly high in many sample results, especially

in sampling prior to 2007.

• The most commonly detected pesticides were:

o For all water samples (groundwater and surface water): Dacthal, Simazine, Atrazine,

Chlorpyrifos, Atrazine‐desethyl, Diuron, Guthion (axinphosmehtyl), and Metolachlor.  

For sample results in 2008 and 2009, the pesticides (mostly in surface water) ranked as

follows: Simazine, Atrazine, Diuron, Metolachlor, and Chlorpyrifos.

o In groundwater only:  Dacthal (DCPA), Atrazine and Atrazine‐desethyl, Acrolein (2‐

Propenal), MCPA, Simazine, Bromacil, 2,4‐D

o In surface water only:  Simazine, Atrazine, Chlorpyrifos, Diuron, Guthion

(Azinphosmethyl), Diazinon, Metolachlor, Malathion, Metribuzin

• Pesticides were detected at a total of 466 sampling locations (325 groundwater locations and

141 surface water locations). Note that sampling locations are focused in areas of known

problems (i.e. the GWMAs) and many waters of the state have not been tested.  
• Pesticides were most commonly detected in the Willamette, Middle Columbia, and Middle

Snake/Boise Basins. See attached table for details.

o In groundwater, pesticides were most commonly detected in the following basins and

subbasins: Willamette (Upper Willamette subbasin), Middle Snake/Boise (Lower

Malheur and Payette subbasins), Middle Columbia (Umatilla, Hood River and Lake

Wallula and Walla Walla subbasins) and Oregon Closed Basin (Summer Lake subbasin).

o In surface water, pesticides were most commonly detected in the following basins and

subbasins: Willamette (highest in Molalla/Pudding, Yamhill and Clackamas subbasins),

and Middle Columbia (Hood and Walla Walla subbasins)

• The types and quantities of pesticides applied in Oregon were reported by pesticide users in

2007 and 2008 under Oregon’s Pesticide Use Reporting System (PURS). The data is reported and

summarized at the Basin scale. Additional resources/time would be necessary to identify

pesticide use as a smaller scale, such as within subbasins or watersheds. Many current‐use

pesticide ingredients are not recognized as analytes in LASAR – for example, only 42 of the top

100 ingredients (in pounds) used statewide in 2008 are recognized as analytes in LASAR.  See

http://www.oregon.gov/ODA/PEST/purs_index.shtml  for more information and the annual

PURS reporting results.

• In this database query, the pesticides evaluated included:

o DEQ Priority Toxics Focus List of current use and legacy pesticides

o Current Use Pesticide Ingredients as reported in the 2007 and 2008 ODA Pesticide Use

Reporting System Report (Appendix A ‐ Top 100 Active ingredients) – Note that many of

the Current Use Pesticide ingredients were not recognized as analytes in LASAR  

o EPA Pesticides of Interest (POI) and Oregon P3 List (also called the Interagency

Pesticides of Interest List).

o Pesticides monitored under SDWA by PWSs (as reported in SDWIS data pull May 5,

2009)

o Combined, these lists include a total of 187 pesticides – 97 were identified as analytes in

LASAR or SDWIS  (reference:   jkh:  “Master List of Pesticides.xlsx”)