Montana · Area of Critical Environmental Concern
Muddy Creek/Big Sheep Creek
BLM found a natural system, a cultural value and a scenic value here, and its plan calls for special management. BLM's records place 1 oil and gas lease and 2 rights of way inside the line today, and 15 grazing allotments cover part of it. It covers 13,098 acres and was designated February 7, 2006, in the Dillon RMP (2006). In the plan's name, RMP stands for resource management plan.
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
The rights of way
2 rights of way sit inside the line. BLM files 2 under non-energy facilities.
- BUTTE FIELD OFFICE2rights of way
The oil and gas leases
1 active oil and gas lease sits inside the line. 0 of it took effect before the area was designated on February 7, 2006.
- LIMA EXPLORATION CO LLC1lease
Grazing allotments
15 grazing allotments cover part of this line. Their permittees aren't named here yet.
- MUDDY CREEK24,299acres
- Allotment USFS-GRZ-10044.01034922,432acres
- Allotment USFS-GRZ-10046.01034912,608acres
- Allotment USFS-GRZ-10035.01034910,427acres
- PHILIP UNIT10,317acres
- Allotment USFS-GRZ-10062.0103497,323acres
- FOUR EYES5,644acres
- RIO PUERCO5,567acres
- PINE CREEK4,851acres
- Allotment USFS-GRZ-10051.0103493,803acres
- Allotment USFS-GRZ-10057.0103493,260acres
- UNAVAILABLE_BSC3,175acres
- Allotment USFS-GRZ-39712.0103491,993acres
- FOUR EYES ISOLATED308acres
- UNLEASED_BSC274acres
The nearest areas
- Everson CreekMontana/Dakotas · 8,815 acres · at least 4 active mining claims, 5 rights of way, 8 grazing allotments covering part of it28miles
- Summit CreekIdaho · 116 acres · 1 right of way, a grazing allotment covering part of it41miles
- Summit Creek RNAIdaho · 194 acres · a grazing allotment covering part of it41miles
- Donkey HillsIdaho · 29,710 acres · 1 right of way, 7 grazing allotments covering part of it45miles
- Centennial MountainsMontana/Dakotas · 40,782 acres · 10 rights of way, 17 grazing allotments covering part of it48miles
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 Muddy Creek/Big Sheep Creek. 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