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EPA predictive trash model (ETAP) aligns with observed data but not a replacement for monitoring, committee says
Summary
A committee member compared EPA's Escape Trash Assessment Protocol (ETAP) risk maps to multi-year trash observations in Central Coast cities and found spatial alignment; members said the model could direct monitoring but cannot replace field observations needed for compliance and permit evidence.
A comparison of EPA's Escape Trash Assessment Protocol (ETAP) predictive outputs and multi-year local trash observations showed similar spatial patterns in several Central Coast cities, a presenter said, but committee members cautioned that model outputs should augment, not replace, direct monitoring.
"So far so good," the presenter said after showing side‑by‑side screenshots for Santa Cruz, noting downtown and river-adjacent areas had higher modelled trash risk and matched observed hotspots. The presenter added the model uses a Bayesian framework and relies on factors such as land-cover development intensity and socioeconomic indices.
Participants discussed practical uses for the model. One committee member said the ETAP output could help cities "focus their efforts" by directing monitoring to predicted high‑risk areas but cautioned the model "is definitely not gonna help cities meet their compliance requirements" under the trash permit without direct observations. The group noted that model inputs (development intensity and socioeconomic variables) change slowly, suggesting updates might be infrequent unless the modelers incorporate new monitoring data.
Committee members also discussed the Trash Free Waters program's solicitation and a form for contributing data to annual model updates. One member volunteered to serve as a point of contact to submit an organizational indication of interest ahead of the spring deadline.
Speakers flagged open questions from the model documentation, including whether training data were kept separate for validation and how often outputs will be refreshed. The presenter said the ETAP documentation indicates they used observed survey data to tune their model but that details on dataset splits and raw data publication were unclear at the time of the meeting.
No formal votes occurred; participants requested follow-up with EPA and suggested continued comparisons of ETAP outputs with local monitoring datasets.
