Unit 52A 52A (Big Desert)
A vast BLM lava-and-sagebrush desert where pronghorn rule and desert elk hide in the lava flows.
South-central Idaho — Big Desert (Butte, Blaine & Minidoka Counties) · Last reviewed 2026-07-12
Area
1,741
sq mi
Public land
85%
approx.
Elevation
4,600–6,200
feet
Motorized
moderate
access
Overview
Unit 52A is the Big Desert — an enormous, largely roadless expanse of sagebrush steppe and basalt lava flows on the northern Snake River Plain, wrapping around the west and south sides of the Idaho National Laboratory and the Craters of the Moon lava fields. It is antelope country first: pronghorn thrive on the open sage flats and post the unit's best success. Mule deer are scattered across the sage and lava-edge brush, and a genuinely unusual desert elk herd uses the broken lava and kipuka islands for cover. This is big, dry, open BLM ground where glass, water knowledge, and a willingness to walk matter more than timber skills.
Terrain
High-desert plain of gently rolling sagebrush flats broken by jagged basalt lava flows, cinder buttes and vegetated kipukas. Little relief and almost no permanent surface water across most of the unit.
Cover: Wyoming big sagebrush, rabbitbrush and native bunchgrass steppe with greasewood in the flats; scattered juniper and denser brush along lava-flow margins and cinder buttes. Cheatgrass and old burns are common.
Landmarks: Big Desert / Great Rift lava flows · Craters of the Moon lava fields (east edge) · Big Southern Butte · Idaho National Laboratory boundary · Pioneer Mountains foothills (north)
Access
Overwhelmingly BLM public land laced with primitive two-track roads; navigation and fuel/water self-sufficiency are the real access limits, not ownership. The Idaho National Laboratory (INL) reservation is closed to public entry — its fenced boundary bounds the unit's northeast. Craters of the Moon National Monument's wilderness and monument core are closed to hunting (the adjacent National Preserve does allow hunting). Ag and ranch parcels line the wetter southern and western fringes.
Managers: BLM (Shoshone & Idaho Falls field offices), Idaho Department of Lands (IDL) endowment, Private ranch/agriculture (fringes), US Dept of Energy — INL (closed)
Access points: Arco (US-20/26) on the north · Aberdeen / Springfield area on the south · BLM Big Desert two-track network · Frenchman's Cabin / Big Butte roads · Atomic City off US-26
Species notes
Pronghorn
common qualityThe signature big game of the Big Desert and a controlled-hunt draw — pronghorn are spread across the open sage flats and post the unit's strongest success rates. Classic spot-and-stalk antelope country.
- →Glass the open sage basins from cinder buttes and rises at first light
- →Use terrain folds and lava rims to close the final stalk
- →Focus near the scarce water sources and greener draws in dry years
- →Bring a spotting scope — bucks are found by grinding glass over big country
Mule Deer
common opportunityDesert mule deer scattered through the sage and along the brushy lava margins; numbers are moderate and bucks are earned by covering ground in featureless country.
- →Hunt the lava-flow edges and kipukas where brush gives cover and thermal relief
- →Glass sage draws and old burns at dawn and dusk
- →Watch for deer holding tight to the broken basalt during warm early seasons
- →Cover miles — deer are thinly and unevenly distributed
Rocky Mountain Elk
limited opportunityAn unusual and prized desert elk herd uses the Big Desert lava and kipukas for cover — a controlled-hunt opportunity where elk behave nothing like their timbered mountain cousins.
- →Hunt the biggest, thickest lava flows and vegetated kipukas where elk bed
- →Glass at the very edges of shooting light — desert elk feed nocturnally
- →Locate scarce water and green feed, then watch the approaches
- →Be prepared for long stalks across open ground with almost no cover
Pro tips
- →This is an antelope unit first — build your hunt around pronghorn and the open sage, then take deer or a desert-elk tag as a bonus
- →Carry far more water and fuel than you think you need; there is none out there
- →Air down and carry two spares — lava rock shreds tires
- →Hunt the lava flows and kipukas for the deer and elk that everyone else glasses past
- →Watch your boundaries: the INL reservation and Craters of the Moon monument core are closed — know exactly where the lines are
Watch out for
- !Idaho National Laboratory (INL) is a closed federal security reservation — do not cross the fence
- !Craters of the Moon Monument/Wilderness is closed to hunting; only the National Preserve portion is open — verify before you hunt the east edge
- !No reliable water anywhere in the interior — dehydration and stranded vehicles are the real hazards
- !Wet weather turns desert roads to impassable gumbo that can trap a truck for days
- !Zero cell coverage and no services once off the highway — go self-sufficient with navigation and recovery gear
Logistics
Arco (US-20/26) anchors the north end with fuel, groceries and lodging; Aberdeen, American Falls and Blackfoot serve the south and east. Once off the highways you are on unsigned BLM two-tracks with no services, no cell coverage and no reliable water — carry everything, air down for the lava rock, and run a GPS. Rain turns the desert clays to impassable gumbo.
Nearest towns: Arco, Aberdeen, Atomic City, American Falls, Blackfoot
Seasons & regulations
This page carries no season dates or regulations. Get current rules from the official Idaho sources:
Research sources: IDFG Hunt Planner — Game Management Units · BLM Idaho — Shoshone Field Office (Big Desert) · NPS — Craters of the Moon National Monument & Preserve (hunting in preserve)
FAQ
- How big is Unit 52A in Idaho?
- Unit 52A (52A (Big Desert)) covers about 1,741 square miles, ranging from roughly 4,600 to 6,200 feet in elevation. Area is computed from the unit boundary polygon.
- How much public land is in Unit 52A?
- Approximately 85% of the unit is public land. Primary managers: BLM (Shoshone & Idaho Falls field offices), Idaho Department of Lands (IDL) endowment, Private ranch/agriculture (fringes), US Dept of Energy — INL (closed). Always verify ownership boundaries on the ground.
- What species does the catalog list for Unit 52A?
- Pronghorn, Mule Deer, Rocky Mountain Elk. For seasons, tags, and regulations, use the official Idaho agency resources linked on this page — this page carries no regulatory information.
Put Unit 52A on your map.
Boundary lines, public/private ownership, topo, and offline maps for this unit — in Baseline Maps, free for 14 days.