Colorado · Area of Critical Environmental Concern
Rio Grande River Corridor ACEC
BLM found a wildlife resource here, and its plan calls for special management. BLM's records place at least 1 mining claim BLM lists as Filed and 1 right of way inside the line today, and six grazing allotments cover part of it. It covers 5,357 acres and was designated December 18, 1991, in the 1991 San Luis RMP. 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
Who holds the claims
At least 1 claim sits inside this line: 0 active and 1 filed and pending, 1 with a holder BLM names. BLM lists 1 as Filed. The claim wasn't located before the area was designated.
- ALMADEX AMERICA 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.
The rights of way
1 right of way sits inside the line. BLM files 1 under non-energy facilities.
- CO DEPT OF TRANS1right of way
Grazing allotments
6 grazing allotments cover part of this line. Their permittees aren't named here yet.
- Pinon Hills14,279acres
- Pinon10,713acres
- La Sauses6,255acres
- Flat Top6,102acres
- River2,561acres
- South Valley1,766acres
The nearest areas
- San Luis Hills ACECColorado · 36,472 acres · at least 3 active mining claims and 79 more BLM lists as Filed, 4 rights of way, 9 grazing allotments covering part of it7miles
- Cumbres and Toltec Scenic Railroad Corridor ACECColorado · 3,904 acres · 4 grazing allotments covering part of it19miles
- Los Mogotes ACECColorado · 33,447 acres · 2 rights of way, 10 grazing allotments covering part of it23miles
- Taos PlateauNew Mexico · 288,234 acres · at least 6 active mining claims, 26 rights of way, 74 grazing allotments covering part of it25miles
- Ra Jadero Canyon ACECColorado · 3,652 acres · 3 grazing allotments covering part of it29miles
More from BLM's Colorado office
Every area BLM's Colorado 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 Rio Grande River Corridor 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