This sign has been placed outside of Station #1 (in central Coal Creek Canyon) by Colorado Parks and Wildlife (formerly Colorado Division of Wildlife.) There have been multiple reports of mountain lions attacking (and killing) dogs in Coal Creek Canyon, even with humans present. The word on this is spreading, but since there have been (at least) 4 attacks on dogs it is important to share this information widely to allow Canyonites to make informed choices.
Here is what Colorado Parks & Wildlife say about living in Mountain Lion Country with the pets portions being:
Keep your pet under control. Roaming pets are easy prey and can attract lions. Bring pets in at night. If you leave your pet outside, keep it in a kennel with a secure top. Don’t feed pets outside; this can attract raccoons and other animals that are eaten by lions. Store all garbage securely.
Further, there is also risk to humans (young, old and in between) that we should pay attention to. Again, check this information from Colorado Parks and Wildlife on Living in Mountain Lion County.
For a few more details, see this posting on mountain lions in Coal Creek Canyon.