2024: Warning signs were installed along trails accessing the former range.

2022 – 2023: Surface and subsurface clearance of munitions items were completed.

2021: The Remedial Design/Remedial Action Plan was completed.

2020: The Community Relations Plan was accepted.

2018: The Record of Decision was finalized.

2017: The Remedial Investigation, Feasibility Study, and Proposed Plan were all finalized.

2016: The Remedial Investigation Work Plan was submitted for ADEQ review.

2012: The Site Inspection was completed.

2011: The Preliminary Assessment was completed.

2008: The site is identified as a Non-Department of Defense, Non-Operational Defense Site and Munitions Response Site (MRS).

1948 – 1950: Arizona Army National Guard (ARNG) artillery training included 105-mm howitzers, 75-mm projectiles, 60-mm and 81-mm mortars, and machine guns. The firing points are unknown for the mortars and machine guns. Historical documents indicate the howitzer firing point was located on the western edge of the MRS and directed east toward an impact point on Maroon Crater.

1948: ARNG acquired a Special Use Permit from the U.S. Forest Service to conduct military training at Maroon Crater.