Idler Range Munitions Response Site

The three “R’s” of munitions safety


  • Recognizing when you may have encountered a munition is key to reducing the risk of injury or death.
  • If you encounter or suspect you’ve encountered a munition, consider it extremely dangerous.
  • Munitions are sometimes hard to see and identify. They may resemble:
    • A pointed pipe.
    • A soda can.
    • A baseball.
    • A muffler.
    • Other metal objects.
  • They may be:
    • Visible on the surface.
    • Buried.
    • Exposed by erosion or fires.
  • They may look new or old, be complete or in parts, be found alone or in groups.
  • Any suspect items should be considered dangerous, regardless of size or apparent age.


  • If you encounter or suspect you’ve encountered a munition, don’t touch, move or disturb it.
  • Immediately and carefully leave the area, following the same path on which you entered.
  • If you can, mark the general area — not the munition — in some manner (e.g., with a hat, piece of cloth, or tying a piece of plastic to a bush or tree branch).


  • Call 911 immediately.
  • Notify local law enforcement of what you saw and where you saw it.
  • If you or someone you know may have collected munitions-related items as souvenirs, please notify law enforcement immediately so trained professionals can remove the items safely.


The Idler Range Munitions Response Site (MRS) encompasses 153 acres and is located approximately four (4) miles south of Highway 50 and approximately six (6) miles southwest of Lamar in Prowers County, Colorado. The MRS is on privately owned land used for seasonal agricultural purposes and occasional hunting. The Idler Range MRS was used by the Colorado Army National Guard (COARNG) from 1950 until 1956. Training included infrequent use of M29 3.5-inch practice rockets and small arms ammunition (SAA) used at a 300-yard Known Distance Rifle Range (0.30-caliber). Idler Range is owned by one private landowner.

Remedial Activities
A CERCLA Site Inspection (SI) was conducted for the Idler Range MRS in 2012 to determine the presence or absence of munitions and explosives of concern (MEC) and munitions constituents (MC). The SI was based on the results of the Preliminary Assessment (PA) that identified a M29 3.5-inch practice rocket. No MEC were observed during the SI. Munitions debris (MD) from fully expended M29, 3.5-inch practice rockets with M405 dummy fuses, nose cones, and fin assemblies were encountered, as well as expended SAA cartridge casings near the firing lines.

A CERCLA Remedial Investigation (RI) was conducted over two (2) separate events in 2017 and 2018 to determine the nature and extent of potential MEC at the MRS and potential impacts to human health and the environment. The RI results did not identify any MEC present at the MRS. Additionally, no explosive hazards or munitions constituents were present at the MRS. 

In 2020, CDPHE concurred with the COARNG that no further action is necessary for the Idler Range MRS for the protection of human health and the environment.