Geostatistical assessment of environmental indicators guides habitat management opportunities in a Great Lakes embayment

• Guide delisting actions in Great Lakes AOCs with geostatistical mapping and visualization. • Set zone specific μ – 3σ thresholds to create sensitive “extremely poor” to “extremely good” classes. • Integrate physical characteristics, sediment chemistry, and habitat ranks to prioritize sites for restoration or protection. As sediment remediation nears completion in the St. Louis River Area of Concern (SLRAOC), managers need a post delisting framework that reaches beyond the original Remedial Action Plan (RAP). We ran estuary-wide geostatistical analyses on physical, chemical, and biological indicators, first trimming outliers below a zone-specific lower control limit (μ − 3σ) and then classifying each metric with quartile cutoff points (Q5, Q25, Q75, Q95) drawn from the remaining least-impaired data. The workflow flagged 1,717 ha of the 8,450 ha estuary for action: 285 ha for restoration and 1,430 ha for long-term protection or adaptive management. Two geomorphic zones illustrate application. In Allouez Bay, a 70-ha wave dampening shoal design would increase the Scaled Tri-Metric Index (s-TMI) from 0.45 to 0.68 and expand native vegetation cover. In Spirit Lake (Lower St. Louis River), a 67-ha sediment remediation footprint is projected to raise benthic habitat scores by 22 %. Because each threshold is recalculated from within estuary reference distributions, targets are stricter and zone specific relative to RAP benchmarks and can be refreshed whenever new monitoring data arrive. A co-developed management strategies with tribal nations, federal agencies, and local partners translated Thiessen polygon metric surfaces into a consensus priority list. Fewer than 6 % of 4,500 station results now classify as “extremely poor,” showing that severe impairment is confined to discrete locations where chemical and biological stressors overlap. The framework feeds directly into feasibility and cost benefit analyses, guides post construction monitoring and provides a transferable template for freshwater embayments seeking data driven, partner-validated restoration plans.