# Relationship history for MSHA mine 0402786

Current hierarchy: **Karen J  Hay; William G  Hay → Bed Rock Products Inc → Twin Bridges**

- 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:** Gualala Ready Mix → Twin Bridges; 1950-01-01 to 1978-04-03; source msha-controller-operator-history
- **controller_controls_mine:** Gualala Ready Mix → Twin Bridges; 1950-01-01 to 1978-04-03; source msha-controller-operator-history
- **controller_controls_operator:** Gualala Ready Mix → Gualala Ready Mix; 1950-01-01 to 1978-04-03; source msha-controller-operator-history
- **operator_operates_mine:** Gualala Aggregates Inc → Twin Bridges; 1978-04-04 to 2003-09-23; source msha-controller-operator-history
- **controller_controls_mine:** Robert B  Swegle  et al → Twin Bridges; 1978-04-04 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert B  Swegle  et al → Gualala Aggregates Inc; 1978-04-04 to 2003-09-23; source msha-controller-operator-history
- **controller_controls_operator:** P Jean  Swegle  et al → Gualala Aggregates Inc; 1978-04-04 to 2003-09-23; source msha-controller-operator-history
- **operator_operates_mine:** Bed Rock Products Inc → Twin Bridges; 2003-09-24 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** William G  Hay  et al → Twin Bridges; 2003-09-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** William G  Hay  et al → Bed Rock Products Inc; 2003-09-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Karen J  Hay  et al → Bed Rock Products Inc; 2003-09-24 to current/open; source msha-controller-operator-history