Skip to main content

Assessment Methodology Updates

2022 Integrated Report

Oregon statute requires that DEQ publish the Integrated Report assessment methodology prior to the start of drafting the Integrated Report. The draft assessment methodology for Oregon’s 2022 Water Quality Report and List of Water Quality Limited Waters, describes how data will be evaluated at the assessment unit level and how DEQ will develop Oregon’s 2022 Integrated Report for Section 305(b) and 303(d). The draft methodology is consistent with the key elements of Oregon’s water quality standards and is the framework DEQ uses to assess water quality conditions. The methodology builds on DEQ’s protocols from previous 305(b)/303(d) assessments. 

​​​The public comment period for the draft assessment methodology for Oregon’s 2022 Water Quality Report and List of Water Quality Limited Waters closed on Monday, March 8, 2021. The following document was provided for stakeholder feedback: 2022 Draft Assessment Methodology 

DEQ reviewed the comments provided, incorporated any changes to the methodology document, and provided a summary of the comments received and responses to comments in the documents below. Please remember to Sign up for Water Quality Assessment Reporting and 303(d) GovDelivery​ to stay informed.

The next public comment opportunity will be for the draft 2022 Integrated Report in late 2021.​

Methodology updates

Before each reporting cycle, DEQ updates the assessment methodology which describes how each assessment unit will be evaluated. The 2022 Integrated Report Methodology update is currently in progress. DEQ priority methodology updates for the 2022 Integrated Report are below. 

Short-term updates

​​A delisting represents that a previously identified issue is no longer applicable for a given assessment unit. To ensure that an assessment unit is not prematurely delisted, a higher degree of certainty is needed to remove parameters from the 303(d) Impaired Waters list than the requirement to add assessment unit impairments to the list. Dissolved oxygen exhibits both seasonal and diurnal patterns that influence waterbody concentrations. Continuous dissolved oxygen data collection has become more widespread with the availability of less expensive data collection equipment. Developing a means to delist for dissolved oxygen using continuous data would provide a clear method to demonstrate attainment of dissolved oxygen criteria.

​As more continuous pH data is being collected throughout the state, DEQ needs to develop a way of evaluating that data against the pH standard.  This update will not replace, but will be in addition to, the current grab sample listing method.

​When the water quality standards for freshwater indicator bacteria were revised to E. coli from fecal coliform, no pathway for addressing historic freshwater fecal coliform listings was identified. DEQ is coordinating with EPA to replace freshwater fecal coliform listings with E.coli, the current indicator bacteria, to make the determination of impairment or attainment for the recreational use.  Through this methodology update, DEQ will work with EPA to correct any historical listings that continue to be propagated in the 303(d) list.

​Category 2 identifies waterbodies where beneficial uses are supported and water quality criteria are being attained. This methodology update would clarify minimum sample requirements for what constitutes "Attainment" of a criteria. This is especially relevant for attainment of Aquatic life toxics criteria, where currently, two samples in a Period of Record (POR = 5 to 10 years) that meet criteria are considered "Fully Supporting" their beneficial use.

​A new aluminum criteria based on total recoverable aluminum is expected to be promulgated by EPA and finalized in January 2021. A methodology to assess the new criteria is essential for the 2022 Integrated Report. This methodology will provide a clear assessment process for how DEQ will assess bioavailable aluminum against a total recoverable criterion. DEQ will work with the agency’s Water Quality programs including Standards, Permitting, Stormwater, and TMDL programs to develop this method.

​To provide more detail to watershed unit assessments and a clear rationale for listing, DEQ intends to assess watershed units at each individual monitoring station. Assessment conclusions will be reported at both the monitoring station and the watershed assessment unit level. If a Category 5 determination is made at the monitoring station level, the watershed assessment unit will be identified as Category 5.

Long-term updates

​DEQ is committed to making updates to the biocriteria methodology based on peer review recommendations received in 2018. DEQ has updated its reference screening protocols, identified additional reference site data, and incorporated new data into its reference screening process.  DEQ is exploring the option of a new or revised model, multimetric index, and additional supporting lines of evidence. This work fulfills DEQ’s commitment to EPA to pursue additional steps and lines of evidence to increase confidence in DEQ’s interpretation of its biocriteria narrative.

​DEQ has begun conversations with sister agencies about exploring methods to assess the impacts of marine hypoxia and ocean acidification with the objective of convening a scientific advisory group to develop assessment methodologies for marine territorial waters. 

​The current assessment method of the Narrative Criteria ORS 340-041-0007(9) lacks specific details and protocols. To support a determination of impairment by aquatic weeds or algae, terms such as “excessive growths” and “dominate the assemblage” must be clarified and a weight of evidence approach defined. This update will add clarity to the existing methodology.

​Oregon’s methodology for listing segments of waterbodies as “impaired” for toxics does not currently include a method for assessing toxics data in tissue. Category 5 listings are based on either water column concentrations of toxic pollutants, or on fish advisories issued by the Oregon Health Authority (OHA). Current method detection limits for many toxic pollutants are greater than existing water column criteria. OHA’s fish advisories are designed for the purpose recommending safe guidelines for consumption of fish harvested in Oregon, therefore the assumptions are different. DEQ is developing tissue concentration thresholds to include in its methodology document that identifies impairment of the “Fishing” use.

​​DEQ is coordinating with EPA to determine, where no numeric criteria exist (i.e. phosphorus, nutrients, sediment), whether attainment of TMDL targets/benchmarks may be used to identify where waterbodies have been restored and beneficial uses are currently being supported.

​DEQ historically listed waterbodies based on excessive amounts of algae (i.e. benthic/floating algae). DEQ is exploring multiple lines of evidence that may be used to assess attainment of this criteria. This update will provide clarity and a clear weight of evidence approach to remove “excessive algae” listings. Lines of evidence may include: methods for visual estimation of algae, periphyton biomass thresholds, algae community composition, and other supporting WQ information such as nutrients, diel dissolved oxygen and/or pH.

Public process

The 2022 reporting cycle will have a robust public process. DEQ hosted informational webinars and workshops for priority updates. Long-term updates will involve technical groups and stakeholder input. 

DEQ has initiated work on the Methodology for Oregon’s 2022 Water Quality Report and List of Water Quality Limited Waters. Oregon statute requires that DEQ publish the Integrated Report Assessment Methodology prior to the start of drafting the Integrated Report. The Assessment Methodology describes how data will be evaluated at the assessment unit level before each two-year reporting cycle. DEQ is evaluating high priority updates that will likely result in changes to 2022 Integrated Report Assessment Methodology. This is the first of several webinars on the Assessment Methodology update. This first webinar will focus on high-level discussions of the priorities for the Assessment Methodology update and opportunities for input on the methodologies. Subsequent webinars will discuss the technical details for specific methodology updates. DEQ anticipates at least one to two additional webinars for these additional discussions and input. DEQ intends to release the draft 2022 Assessment Methodology for public comment early next year.


For more information on the Integrated Report, please contact:

Connie Dou, 503-853-6517
WQ Assessment Manager

Sign up for Water Quality Assessment Reporting and 303(d) GovDelivery topic to stay up to date on public processes and data calls