Buying land in San Juan County, Colorado: what to check
San Juan County covers 388 square miles of land in Colorado, with about 821 residents in 2024 (up 17.1% since 2020). The 2020 Census counted 100% of its land as rural and 0% of residents as living in urban areas. Below: how much of San Juan County floods, what its soils allow, what farmland is worth and how often it's in drought, from free public data with every source linked.
San Juan County at a glance
In the 100-year floodplain
under 1%
About the state's county median (under 1%)
Hydric (wetland-type) soils
1.7%
About the state's county median (1.7%)
What to check before buying land in San Juan County
Ordered by what San Juan County's numbers point to. Every parcel differs, so treat this as where to look first.
1.Check slope where you'd build and where the driveway goes
77% of San Juan County's mapped soils have an average slope over 15% (USDA SSURGO).
Steep ground means grading, retaining walls, longer driveways and erosion control. Compare the slope at the house site and along the access route, not just the parcel average.
2.Budget for a perc test and maybe an engineered septic
USDA rates 100% of San Juan County's mapped soils "very limited" for conventional septic absorption fields and 0% "not limited".
Without city sewer you need a septic permit from the county or state health department. Make the offer contingent on a passing soil or perc test; mound and aerobic systems can cost several times a conventional one.
3.Find out where the water comes from
At least half of San Juan County was in severe drought (D2) or worse in 20% of the 262 weekly U.S. Drought Monitor maps from 2021 to 2026. Colorado allocates water by permit or water right, so a well or pond isn't automatic.
Ask whether the land has a public water connection, an existing well (and its log and yield), or neighbors' well depths from the state well database. For a new well, check permits and typical depth with the state agency first.
4.Confirm legal road access and power
The 2020 Census classified 100% of San Juan County's land area as rural.
Rural tracts are often sold without recorded access or a power line nearby. Get the title company to confirm a recorded easement or public road frontage, and ask the electric co-op what a line extension costs.
5.Confirm the flood zone at your exact spot
under 1% of the county's area is in the 1%-annual-chance (100-year) floodplain FEMA's National Risk Index uses for inland flooding; 1.5% of its mapped soils flood occasionally or frequently.
Even where little of the county floods, creeks and low spots do. Check the FEMA zone at the building site and the driveway route.
6.Rule out wetlands on the part you'll use
About 1.7% of San Juan County's mapped soils are hydric (formed under saturated conditions, a federal wetland indicator) and 2% are poorly or very poorly drained (USDA SSURGO).
Open the National Wetlands Inventory mapper at the parcel. Filling or draining a wetland can need a Clean Water Act Section 404 permit, and wet ground limits septic fields and building pads.
Flood zones, wetlands and water in San Juan County
- Area in the 1%-annual-chance (100-year) floodplain
- under 1%, 11th lowest of 64 in Colorado FEMA National Risk Index
- Mapped soils that flood occasionally or frequently
- 1.5% USDA NRCS Web Soil Survey (SSURGO)
- Hydric soils (a federal wetland indicator)
- 1.7% USDA NRCS Web Soil Survey (SSURGO)
- Poorly or very poorly drained soils
- 2% USDA NRCS Web Soil Survey (SSURGO)
- Surface water (lakes, rivers, reservoirs)
- 1 sq mi Census 2024 Gazetteer Files
- Drought on 2026-10-27
- 0% moderate or worse, 0% severe or worse U.S. Drought Monitor county statistics
The floodplain share is the area FEMA's National Risk Index counts as exposed to inland flooding, mostly mapped 100-year flood zones. It says how common flood-prone land is in San Juan County, not whether a given parcel floods. For that, look up the zone at your exact point on the FEMA Flood Map Service Center or run the free check.
Soils and terrain
- Prime farmland
- 0% USDA NRCS Web Soil Survey (SSURGO)
- Prime only if drained, irrigated or protected
- under 1% USDA NRCS Web Soil Survey (SSURGO)
- Farmland of statewide importance
- under 1% USDA NRCS Web Soil Survey (SSURGO)
- Average slope over 15%
- 77% USDA NRCS Web Soil Survey (SSURGO)
- Very limited for septic absorption fields
- 100% USDA NRCS Web Soil Survey (SSURGO)
- Not limited for septic absorption fields
- 0% USDA NRCS Web Soil Survey (SSURGO)
Shares of San Juan County's soil-surveyed land (about 247,918 acres, open water excluded), using each map unit's dominant condition in USDA's SSURGO soil survey. Soils change within a few hundred feet, so the soil at your building site is what matters.
Natural hazard ratings
FEMA's National Risk Index rates each hazard for San Juan County relative to every other U.S. county. Overall risk: Very Low.
- LandslideRelatively Low
- LightningRelatively Low
- EarthquakeVery Low
- HailVery Low
- River and inland floodingVery Low
- Strong windVery Low
- TornadoVery Low
- WildfireVery Low
- Winter weatherVery Low
FEMA National Risk Index, December 2025
Questions about buying land in San Juan County
How much of San Juan County, CO is in a flood zone?
About under 1% of San Juan County's area is in the 1%-annual-chance (100-year) floodplain used by FEMA's National Risk Index (December 2025), 11th lowest of 64 counties in Colorado. Whether a given parcel is in a flood zone depends on its exact location, so check the FEMA map at your pin.
Will a septic system work on land in San Juan County?
Often, but test first. USDA soil surveys rate 100% of San Juan County's mapped soils very limited for conventional septic absorption fields, usually because of wetness, slow permeability, shallow rock or flooding. A perc or soil test on the parcel decides what system the health department will permit.
Is there good farmland in San Juan County?
0% of San Juan County's mapped soils are prime farmland, under 1% are prime only if drained, irrigated or protected from flooding, and under 1% are farmland of statewide importance (USDA SSURGO).
How often is San Juan County in drought?
Since 2021, at least half of the county was in severe drought or worse in 20% of weekly U.S. Drought Monitor maps, and in extreme drought in 11%. On 2026-10-27, 0% of the county was in moderate drought or worse.
Can I check a specific property in San Juan County?
Yes. Enter the address or drop a pin anywhere in San Juan County on the free check. It shows which checks return data at that exact point, and the full report costs $29: flood zone, slope, soils, wetlands, roads, power lines, wildfire and more, each with its source. It is a screen of public maps, not a survey, title search or perc test.
Check the parcel, not just the county
County numbers tell you what to look for. The free check looks at your exact point in San Juan County: flood zone, slope, soils, wetlands, roads, power and more. The full report is $29.
What these numbers can't tell you
- County shares describe San Juan County as a whole; a parcel can be entirely in or out of a flood zone, wetland or poor soil.
- It doesn't look at the whole parcel, its boundaries, title, easements, zoning or permits.
- It isn't a survey, appraisal, elevation certificate, soil or perc test, or Phase I environmental site assessment.
- It can't see local distribution power lines, driveways, legal access, wells or mineral rights.
- Maps lag behind the ground, and distances are straight-line, not driving distance.
Sources and vintages
- U.S. Census Bureau, 2024 Gazetteer Files: 2024 files
- U.S. Census Bureau, Vintage 2024 county population estimates: Vintage 2024 (July 1, 2024)
- U.S. Census Bureau, 2020 Census urban and rural classification: 2020 Census
- U.S. Census Bureau, 2024 county adjacency file: 2024
- FEMA National Risk Index: December 2025 release
- USDA NRCS Web Soil Survey (SSURGO): Soil Data Access, queried 2026-10-31
- U.S. Drought Monitor county statistics: weekly maps 2021-10-26 to 2026-10-27
- FEMA Flood Map Service Center: look up your own pin
- USFWS National Wetlands Inventory mapper: look up your own pin
Summarized per county by our build script on 2026-10-31. County figures cover the whole county; checks on the report are at your point.