Arizona · Area of Critical Environmental Concern
Black Knolls
BLM found a natural system here, and its plan calls for special management. BLM's records place at least 1 active mining claim and 1 right of way inside the line today, and two grazing allotments cover part of it. It covers 428 acres and was designated January 29, 2008, in the Arizona Strip Field Office RMP and ROD. In the plan's name, RMP stands for resource management plan and ROD for record of decision.
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 1 claim sits inside this line: 1 active, 1 with a holder BLM names. BLM lists 1 as Active.
- WESTERN MINING & MINERALS1claim
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.
The rights of way
1 right of way sits inside the line. BLM files 1 under non-energy facilities.
- RIO VIRGIN TEL CO DBA RELIANCE CONNECTS1right of way
Grazing allotments
2 grazing allotments cover part of this line. Their permittees aren't named here yet.
- Curly Hollow28,055acres
- Lambing-Starvation13,417acres
The nearest areas
- StatelineUtah · 1,410 acres · 3 rights of way, 2 grazing allotments covering part of it2miles
- Lower Virgin RiverUtah · 1,806 acres · 3 grazing allotments covering part of it2miles
- Webb HillUtah · 520 acres · 8 rights of way6miles
- Red BluffUtah · 6,166 acres · 1 right of way, 3 grazing allotments covering part of it7miles
- Little Black MountainArizona · 241 acres · a grazing allotment covering part of it8miles
More from BLM's Arizona office
Every area BLM's Arizona 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 Black Knolls. 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