# Relationship history for MSHA mine 3503746

Current hierarchy: **Brent  Kerr → Columbia Northwest Recycling Inc. → Portable 1**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Columbia Northwest Recycling Inc. → Portable 1; 2010-04-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Brent  Kerr → Portable 1; 2010-04-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brent  Kerr → Columbia Northwest Recycling Inc.; 2010-04-14 to current/open; source msha-controller-operator-history