Wyoming · Area of Critical Environmental Concern
Sheep Mountain Anticline ACEC
BLM found a scenic value and a natural process here, and its plan calls for special management. BLM's records place at least 7 active mining claims inside the line today, and five grazing allotments cover part of it. It covers 13,316 acres and was designated November 8, 1990, in the Cody 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
Who holds the claims
At least 7 claims sit inside this line: 7 active, 1 with a holder BLM names. BLM lists 7 as Active.
- Several claimants on BLM's record6claims
- WYO-BEN INC1claim
BLM's mining rules list designated ACECs among the places where mining that disturbs the surface beyond casual use needs a plan of operations BLM approves. Exploration of five acres or less can go ahead on a notice instead.
Grazing allotments
5 grazing allotments cover part of this line. Their permittees aren't named here yet.
- Himes-Spence29,079acres
- West River22,636acres
- North Shell Group21,858acres
- Sheep Mountain 101414,789acres
- Big Horn River Riparian Tracts976acres
The nearest areas
- Five Springs Falls ACECWyoming · 160 acres · 2 rights of way, 2 grazing allotments covering part of it16miles
- Brown/Howe Dinosaur ACECWyoming · 5,521 acres · 9 rights of way, 4 grazing allotments covering part of it16miles
- Red Gulch Dinosaur Tracksite ACECWyoming · 1,795 acres · 2 grazing allotments covering part of it20miles
- Little Mountain ACECWyoming · 21,443 acres · 1 right of way, 6 grazing allotments covering part of it23miles
- Pryor FoothillsMontana/Dakotas · 2,606 acres · 3 grazing allotments covering part of it31miles
More from BLM's Wyoming office
Every area BLM's Wyoming 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 Sheep Mountain Anticline ACEC. 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