State Water Board staff and advisory-group members presented updated methods on how the state will flag wastewater systems and treatment facilities as “inadequate” and assess risk, laying out separate formulas for collection systems regulated under the sanitary sewer system general order (SSS Go), NPDES-permitted plants and facilities subject to Waste Discharge Requirements (WDR).

The state team said the approach will treat inadequacy and risk as distinct analyses and calculate separate scores for each facility type, then share initial lists with regional boards, the Water Board executive team and the advisory group before any public release.

The updated collection-system (SSS Go) criteria would flag a system as inadequate if it met two or more conditions from categories that include high rates of sanitary sewer overflows (SSOs), spill recovery performance, missing plans or certifications, and enforcement history. "If a system has has met the inadequacy criteria for 2 or more of the criteria that is going to be presented, then that system would be flagged as inadequate," said staff member Grace Harrison during the presentation.

The NPDES and WDR approaches rely more heavily on federal and existing state designations. For NPDES-regulated plants, the advisory team will rely largely on EPA’s “significant noncompliance” (SNC) definition — including missing discharge monitoring reports (DMRs), missed compliance-schedule milestones and repeated effluent exceedances — while the WDR assessment combines chronic effluent violations, open enforcement orders and a weighted set of monitoring-and-reporting (M&R) violations.

Staff said some variables (for example, certain monitoring-reporting violations) will be weighted rather than treated as binary flags, and acknowledged the need to avoid labeling systems that are already actively addressing problems via enforcement orders or implementation plans. Staff described the process to refine the lists: model the criteria, share an initial list internally, then with the regional boards and finally with the advisory group before any public-facing publication in the final report.

Advisory-group members recommended banding or size-based thresholds so small systems are not unfairly classified for single events, combining multiple reporting measures into a single reporting variable to reduce false positives, and clarifying whether systems under active enforcement but making progress should remain on an inadequate list. Staff said those checks will be part of back-end filtering prior to public release.

The state also described a separate, multi-part risk assessment that will include socioeconomic indicators (household burden, DAC status, majority communities of color), operational metrics (percent cleaned annually, percent inspected by CCTV, system age) and environmental/public-health factors (proximity to impaired waters, drought/flood exposure, presence of constituents of emerging concern). Many of those thresholds are still under development and will be refined during upcoming office hours and advisory meetings.

Direction and next steps: staff will continue to refine thresholds and weighting, operationalize the criteria against the facilities database, share initial lists with regional boards for validation and then present results to the advisory group before publishing a final, public list in the phase 1 report.