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OPP Guidance for Submission of State and Tribal Water Quality Monitoring Data

Inclusion of Water Quality Monitoring Data in OPP's Registration Review Risk Assessment & Management Process


This guidance describes the process for the submission of state and tribal surface and groundwater monitoring data, including but not limited to Clean Water Act (CWA) 303(d) & 305(b) data, for consideration in exposure characterizations for ecological and human health risk assessments and in risk management decisions for pesticide registration review.

Target Audience

  • State and tribal pesticide lead agencies.
  • State and tribal water agencies.


EPA's Office of Pesticide Programs (OPP) published the final rule for pesticide registration review on August 9, 2006 with an effective date of October 10, 2006. This program ensures that all pesticides continue to meet current health and safety standards. The Congressional goal is to review all existing pesticides every 15 years. To support this process OPP is interested in obtaining all available pesticide monitoring data that states and tribes may have for surface water and groundwater.

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How does OPP use water monitoring data from states and tribes?

Monitoring data provide snapshots of pesticide concentrations in time at specific locations. In order for us to make the best use of this data, we need supporting information that will allow us to put the results in context with the larger picture of pesticide exposures in the environment. The more likely the monitoring sites reflect areas that have a likelihood of pesticide occurrence in water (based on pesticide use as well as local runoff and/or leaching vulnerability), sampling occurs during the time frame in which pesticides are expected to be used, and the sampling is frequent enough to estimate exposures for the endpoints of concern, the more likely OPP will be able to incorporate that data quantitatively in its risk assessment.

Typically, monitoring data are screened to identify any detection above modeled values. We do not evaluate the data in a comprehensive manner unless the screening/Tier 1 assessments identify a risk of concern that triggers more refined/Tier 2 assessments.

For Tier 2 assessments, when we use monitoring data quantitatively it means that the data can be used as a direct measure of exposure in an ecological or human health dietary assessment. This is a high hurdle to clear because much of the monitoring data available are often not targeted to a particular use pattern or of sufficient frequency to capture durations of concern.

How we use monitoring data quantitatively depends on the ancillary data: key among these factors is sample frequency. Sample frequency relative to the duration of concern (e.g., daily peak vs. annual mean) is a key driver in determining how monitoring data can be used quantitatively. However, with adequate ancillary data, monitoring data may be used as direct inputs into risk assessment models. Also, it is possible that while a data set may not be national in scope, it may provide a quantitative measure on a regional or local scale in which case it could be used as a local refinement to national modeling.

If we cannot use a monitoring data set quantitatively, it may still be valuable in providing context to the exposure assessments. For instance, detections of a given pesticide can provide a measure of a lower bound estimate of exposure for purposes of risk assessment. While the data may not be robust enough to ensure a high-end exposure has been observed, the detections do indicate that transport has occurred in the study. At a minimum, qualitative data can provide a balance against modeled estimates and can be useful for characterization of risk conclusions. For example, refinements to modeling sometimes use alternative assumptions that may reduce predicted concentrations. However, if these predicted concentrations approach or are lower than those seen in monitoring data, then this may call into question the appropriateness of the refinement.

For more information on how we use water quality monitoring data in our aquatic exposure assessments, see Evaluation and Use of Water Monitoring Data in Pesticide Aquatic Exposure Assessments.

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What are the most important elements needed for OPP to use the data?

OPP recognizes that the types of water quality data collected might be different among monitoring programs. Water monitoring data would be most useful for risk assessment purposes if it included the following elements for surface water and groundwater:

  • Study objective (i.e., purpose and design of the monitoring study); a copy of a report describing the purpose and design of the monitoring study or internet web address leading to this information would be useful if available.
  • Location description (latitude & longitude, if possible, or other reliable location information).
  • Water body type (stream, river or other flowing body; lake, reservoir, or other static body; groundwater; nature of aquifer, e.g., surficial or confined).
  • Date sampled.
  • Sample media (e.g., water, filtered water, bed sediment, tissue).
  • Chemical analyzed and reported concentration.
  • Analytical method and detection limit (LOD) or limit of quantitation (LOQ).
  • Depth to water level for groundwater.
  • Well characteristics, such as well depth, screened interval, and aquifer type if known (e.g., confined vs. unconfined).
  • Well purpose (e.g., ambient vs. drinking water).

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What other important information aids in interpreting monitoring data?

  • Quality assurance (QA)/quality control for sample collection and analytical methods, including a discussion of any limitations of the data.
  • Time of sample [e.g., date, time; duration (if a composite), timing to stream hydrograph ( if flow-weighted sample)].
  • Sample collection method (e.g., grab or composite).
  • Time frame and duration of monitoring sampling.
  • Land use, including cropping pattern, agriculture/urban, etc. preferably in immediate vicinity of sample site though general information on specific pesticide use sites would be useful.
  • Pesticide usage that could affect water quality at sampling location.
  • Did the sampling methodology and analytical methods go through a formal QA process? If yes, is this process documented (e.g., in a report or on a website address)?
  • For pesticides that adsorb to sediments: percent organic carbon, bulk density, etc.
  • For some chemicals, environmental conditions (e.g., temperature, pH, hardness, turbidity) may affect mobility and persistence. If this is known to occur, information on the parameter would be helpful in interpreting the data.

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Should I submit data that are already publicly available?

As a matter of routine, OPP typically checks and reviews the following sources for pesticide monitoring data:

If a state’s or tribe’s monitoring data are already contained within these sources, then simply let OPP know. If your data are available on another publicly accessible website, please send us the link.

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How do I know which pesticides OPP is re-evaluating?

  • Federal Register (FR) Notification:
    • Registration Review Initial Docket Openings for Comment: At the beginning of a review cycle, OPP notifies the public of docket openings through an FR Notice and seeks comment on OPP’s anticipated chemical-specific work plans and data needs. Dockets are generally opened for comment in the months of September, December, March, and June.
    • Registration Review Draft Risk Assessments for Comment: In general, OPP expects to release draft risk assessments on a quarterly basis for public comment through an FR notice.
    • Registration Review Proposed Decisions: OPP will announce the release of proposed decisions for public comment through an FR notice. 
  • E-mail Notification: In addition to notification through the FR, OPP also notifies the EPA Office of Water (OW) and EPA Regional pesticides and water staff of pesticide cases undergoing re-evaluation in order to facilitate communication with state and tribal partners regarding these actions.

See the schedule for chemicals currently in review and those scheduled for review over the next four years.

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When should I submit data to OPP?

Data can be submitted to OPP at any time during the registration review process, which generally takes about six years. However, data are of most value approximately six months prior to initiating work on a draft risk assessment. OPP and OW will notify EPA Regional pesticides and water staff on a yearly basis, targeting the first quarter of the fiscal year, of the draft risk assessments that OPP intends to release for public comment that year. Regions will work with state and tribal water and pesticide agencies to submit identified data. OPP will publish draft risk assessments for public comment (generally for 60 days) and ask for comment, as well, on possible/practical risk management options for identified risks.

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Where should I submit the data?

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Who do I contact for further information?

EPA Headquarters

Tracy L. Perry (
Pesticide Re-Evaluation Division, Office of Pesticide Programs
Telephone number: (703) 308-0128; Fax number: (703) 308-8090

EPA Regions

Region 1 Rob Koethe (617) 918-1535
Region 2 Audrey Moore (732) 906-6809
Region 3 John Butler (215) 814-2127
  Christine Convery (215) 814-2249
  Courtenay Hoernemann (215) 814-2216
Region 4 Richard Corbett (404) 562-9008
Region 5 Bruce Wilkinson (312) 886-6002
Holly McDonald (312) 886-6012
Region 6 Jerry Collins (214) 665-7562
Region 7 Damon Frizzel (913) 551-7560
Region 8 Peg Perreault (303) 312-6286
Region 9 Patti TenBrook (415) 947-4223
Region 10 Gabriela Carvalho (206) 553-6698