Montana · Area of Critical Environmental Concern
Azure Cave
BLM found a natural system and a wildlife resource here, and its plan calls for special management. BLM's records place no claim, lease or right of way inside the line today, and a grazing allotment covers part of it. It covers 143 acres and was designated September 19, 1994, in the HiLine RMP (2015). In the plan's name, RMP stands for resource management plan. The plan's name carries a later year than that date: BLM's map gives the date it records for the area, and a plan approved later can carry forward an area designated earlier.
One of the 1,120 places the Bureau of Land Management has designated an Area of Critical Environmental Concern. This page shows its line, what BLM found there and what sits inside it.
The line
Ground: USGS The National Map, topographic tiles. Boundaries: BLM's own, read Oct 20, 2026. The grazing allotment below isn't marked.Grazing allotments
A grazing allotment covers part of this line. Its permittee isn't named here yet.
- MT0563025,571acres
The nearest areas
- Zortman/Landusky Mine ReclamationMontana/Dakotas · 2,686 acres · at least 4 active mining claims, 17 rights of way, 2 grazing allotments covering part of it3miles
- Cow CreekMontana/Dakotas · 19,414 acres · 6 grazing allotments covering part of it20miles
- Acid Shale-Pine ForestMontana/Dakotas · 2,674 acres · 6 grazing allotments covering part of it55miles
- Malta GeologicMontana/Dakotas · 6,153 acres · 1 right of way, 4 grazing allotments covering part of it56miles
- Big Bend of the Milk RiverMontana/Dakotas · 1,992 acres · 1 right of way, 6 grazing allotments covering part of it58miles
More from BLM's Montana/Dakotas office
Every area BLM's Montana/Dakotas office holdsThe proposed rule
A proposed rule, RIN 1004-AF53, would change how BLM drafts every land use plan, and how it designates ACECs like Azure Cave. The comment window hasn't opened: the proposed rule wasn't in the Federal Register at our last check. The Watch sends one email the day it prints.
The rule's abstract
The purpose of this rulemaking is to establish in regulations an updated process for the approval of the development, revision, amendment, and maintenance of land use plans, as provided for by the Federal Land Policy and Management Act of 1976, for public lands administered by the Bureau of Land Management (BLM). Additionally, this rulemaking will provide clarification of the process the BLM uses for designating Areas of Critical Environmental Concern.Unified Agenda entry for RIN 1004-AF53, Publication ID 2026, reginfo.gov (OMB OIRA), read Oct 18, 2026