Carbondale's Radon Picture, Straight
Carbondale (population 6,434) is in Garfield County, which the EPA designates Zone 1 — the highest predicted-risk category — and the county's own numbers back the map up: about 40% of tested homes come back above the 4.0 pCi/L action level. The cause is the same as everywhere in the Roaring Fork drainage: uranium-bearing rock and soil throughout the Colorado Rockies, fractured rock that gives soil gas pathways upward, and a long heating season during which sealed, warm houses actively pull that gas indoors. Roughly two in five Carbondale tests find a problem. The good news: finding out costs nothing here, and fixing it is a one-day job for most homes.
One ZIP, Four Counties — Don't Let 81623 Confuse You
Carbondale's ZIP code, 81623, is enormous — it sprawls across four counties. The town itself is Garfield County, but the ZIP reaches deep into the Crystal River Valley, where a "Carbondale" mailing address in Redstone is actually in Pitkin County and one in Marble is in Gunnison County. That matters because free-kit programs, county health contacts, and risk statistics are organized by county, not ZIP. If you're not sure which county your parcel is in, call us — we'll tell you, and we'll point you at the right free-kit counter before we talk about anything that costs money.
Free Test Kits, Year-Round, In Town
Garfield County residents have the easiest free-kit access in the valley: CLEER at the Third Street Center (520 S 3rd St) stocks free kits year-round right in Carbondale, and Garfield County Public Health in Glenwood Springs (2014 Blake Ave) does the same — they'll even mail one (970-665-6383). Run the kit in winter under closed-house conditions for the most honest number. When the result matters legally — a home sale, a landlord disclosure, a number you need to defend — step up to a licensed professional continuous-monitor test.
High Number? Here's the Fix
Most Carbondale homes take the standard cure: a sub-slab depressurization system — diagnostics first, a sealed pipe run routed cleanly, a quiet fan outside the living space, a manometer, and a 48-hour verification test to prove the number dropped. Most Colorado systems run roughly $1,200–$3,000; homes with walkout basements, crawlspaces, or mixed foundations (common on the hillsides and older in-town blocks) can run more — see the cost guide for the full breakdown. Selling or buying? Colorado law requires sellers to disclose known radon results, and objection deadlines move fast — our real-estate radon guide covers how mitigation gets done on transaction timelines.
Up the Crystal: Redstone and Marble
We serve the Crystal River Valley from Carbondale, up CO-133 through Redstone (population 127 — technically Pitkin County, so its free-kit program runs through Pitkin's January distribution in Aspen) and on to Marble (population 133 — Gunnison County, where the practical free option is CDPHE's one-kit-per-household-per-year program). Many Crystal Valley homes are on private wells, and in Colorado mountain communities well water is a genuine second radon pathway — if that's your setup, read radon in well water before you test.