# Relationship history for MSHA mine 3500503

Current hierarchy: **Knife River Corporation → Knife River Corporation-Northwest → KEIZER PIT & PLANT**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Keizer Sand & Gravel → KEIZER PIT & PLANT; 1950-01-01 to 1989-07-14; source msha-controller-operator-history
- **controller_controls_mine:** Jack  Douglas → KEIZER PIT & PLANT; 1950-01-01 to 1989-07-14; source msha-controller-operator-history
- **controller_controls_operator:** Jack  Douglas → Keizer Sand & Gravel; 1950-01-01 to 1989-07-14; source msha-controller-operator-history
- **controller_controls_mine:** J Scott  Erickson → KEIZER PIT & PLANT; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Keizer Sand & Gravel → KEIZER PIT & PLANT; 1989-07-15 to 2005-05-31; source msha-controller-operator-history
- **controller_controls_mine:** D C Walker Enterprises Inc → KEIZER PIT & PLANT; 1989-07-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** D C Walker Enterprises Inc → Keizer Sand & Gravel; 1989-07-15 to 2005-05-31; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → KEIZER PIT & PLANT; 1998-03-05 to 2023-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Keizer Sand & Gravel LLC → KEIZER PIT & PLANT; 2005-06-01 to 2011-01-09; source msha-controller-operator-history
- **controller_controls_mine:** Donna L  Bebout → KEIZER PIT & PLANT; 2005-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Donna L  Bebout → Keizer Sand & Gravel LLC; 2005-06-01 to 2011-01-09; source msha-controller-operator-history
- **operator_operates_mine:** Viesko Redi Mix Inc → KEIZER PIT & PLANT; 2011-01-10 to 2019-03-04; source msha-controller-operator-history
- **controller_controls_operator:** J Scott  Erickson → Viesko Redi Mix Inc; 2011-01-10 to 2019-03-04; source msha-controller-operator-history
- **operator_operates_mine:** Knife River Corporation-Northwest → KEIZER PIT & PLANT; 2019-03-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Knife River Corporation-Northwest; 2019-03-05 to 2023-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Knife River Corporation → KEIZER PIT & PLANT; 2023-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Knife River Corporation → Knife River Corporation-Northwest; 2023-06-01 to current/open; source msha-controller-operator-history