California · Area of Critical Environmental Concern
Lost Valley
BLM found a natural system, a wildlife resource and a natural process here, and its plan calls for special management. Nothing that BLM's records place sits inside the line today. It covers 39 acres and was designated September 25, 2006, in the Ukiah.
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.Inside the line
Nothing sits inside this line that BLM's records place: no mining claim, lease, right of way or grazing allotment.
The nearest areas
- Black ForestCalifornia · 254 acres · nothing placed inside19miles
- Indian ValleyCalifornia · 101 acres · nothing placed inside31miles
- Walker RidgeCalifornia · 3,433 acres · 2 rights of way32miles
- CedarsCalifornia · 1,558 acres · nothing placed inside32miles
- StornettaCalifornia · 885 acres · 1 right of way, 2 grazing allotments covering part of it35miles
More from BLM's California office
Every area BLM's California 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 Lost Valley. 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