Well water in Rio Blanco County, Colorado

Name: Private well water quality in Rio Blanco County, Colorado
Creator: Well Water Nerd
License: Public domain (US federal government data)

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Testing strongly recommended

tested well samples in Rio Blanco County exceeded the EPA limit for fluoride (4 mg/L), based on public data from USGS Water Quality Portal.

2,214 test results across 9 contaminants from at least 159 wells, 1951 to 2019; fluoride has the most at 390. Data refreshed September 15, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

An estimated 1,851 people in Rio Blanco County get their drinking water from a private well, per USGS 2015 county water use. That is about 28% of residents.

Separately, the USGS national arsenic model estimates that 1% of the 1,851 people on private wells in Rio Blanco County draw water above 10 ug/L (the model's range is 1% to 2%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Rio Blanco County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Above limit	Samples	Detected	Median	Highest	Limit
Fluoride 1958 to 2019	47%	390	99%	3.3	95	4 mg/L EPA limit
Arsenic 1971 to 2017	27%	278	83%	3.6	150	10 ug/L EPA limit
Lead 1971 to 2017	7%	229	55%	0	1,200	15 ug/L EPA limit
Copper 1971 to 2017	0%	122	48%	0	0.15	1.3 mg/L EPA limit
Uranium 2000 to 2017	0%	36	53%	0.006	8.64	30 ug/L EPA limit
Iron 1971 to 2019	no limit	386	91%	71.2	150,000	300 ug/L nuisance level
Chloride 1951 to 2019	no limit	386	99%	14	18,000	250 mg/L nuisance level
Manganese 1971 to 2019	no limit	384	79%	11.8	4,200	300 ug/L health guideline

Sampled fewer than 10 times, too few to summarize: Sodium (3).

Over time

Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.

Contaminant	before 2000	2000s	2010s	2020s
Fluoride	45%299 samples	65%20 samples	48%71 samples	n/a
Arsenic	29%242 samples	30%20 samples	0%16 samples	n/a
Lead	7%193 samples	10%20 samples	0%16 samples	n/a
Copper	0%86 samples	0%20 samples	0%16 samples	n/a
Uranium	n/a	0%20 samples	0%16 samples	n/a

Fluoride above the limit in Rio Blanco County fell from 65% of 20 samples in the 2000s to 48% of 71 in the 2010s.

Arsenic, lead, copper have held within a few points between the two most recent periods with enough samples.

Closer than the county

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

The contaminants most often above their limit here are fluoride (47% of 390 samples), arsenic (27% of 278 samples), and lead (7% of 229 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Iron, Chloride, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Rio Blanco County

1
Fluoride
47% of 390 local samples were above the limit.
2
Arsenic
27% of 278 local samples were above the limit.
3
Lead
7% of 229 local samples were above the limit.
4
Coliform bacteria
Recommended for every private well, every year.
5
Nitrate
Recommended for every private well, especially near farms or septic systems.
6
Chloride
Detected in 99% of local samples.
7
Iron
Detected in 91% of local samples.

Test your Rio Blanco County well for fluoride, arsenic and lead

Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.

Order the Tap Score well water test kit, from $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in Colorado: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Rio Blanco County numbers, $29. Every line explained, ranked by what matters, with the fix for each.

The rock under Rio Blanco County

Colorado Plateaus aquifers

Sandstone. Sandstone wells draw from pore space in the rock and tend to be dependable. Iron, manganese and hardness are common, and some sandstones carry arsenic or radium, so a first test should include both.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county centroid. A single well can sit in a different unit, especially near a boundary.

Official help in Colorado

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Private well water and your health, CDPHE
Drinking water lab certification, CDPHE

Contamination sources on record in Rio Blanco County

CDPHE operating landfills records 1 regulated sites in Rio Blanco County, among 1 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

1: lined landfill or transfer facility

Treatment that fits the local profile

Fluoride

Point-of-use reverse osmosis; Activated alumina; Distillation

Arsenic

Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange

Lead

Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching

Chloride

Point-of-use reverse osmosis; Distillation

Iron

Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration

Systems we would look at first

Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.

For fluoride

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For fluoride

Aquasana SmartFlow reverse osmosis

under-sink or countertop, about $225

Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.

For arsenic

Whole-house arsenic and uranium filter

whole-house, at the point of entry, about $2,500

Adsorptive iron-based media; sized to your well yield.

For lead

Aquasana Claryum 3-Stage under-sink filter

under-sink or countertop, about $175

Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.

For lead

Acid neutralizing filter

whole-house, at the point of entry, about $1,200

Raises pH so plumbing stops leaching lead and copper.

For iron

Iron and manganese oxidizing filter

whole-house, at the point of entry, about $1,800

Air-injection or greensand media; fixes staining at the source.

Free, no obligation

Get on the list for a free in-home water test in Rio Blanco County

No water treatment company serves Rio Blanco County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Rio Blanco County, and you get an email naming it first.

Common questions

Is there arsenic in well water in Rio Blanco County?

Arsenic was detected in 83% of 278 public well samples in Rio Blanco County, and 27% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How often should I test a private well in Rio Blanco County?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Counties near Rio Blanco County

Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.

Want the numbers themselves? Download the Colorado dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 2,214 samples in Rio Blanco County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
USGS national arsenic model (Ayotte 2017): estimated share of 1,851 people on private wells in Rio Blanco County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
CDPHE operating landfills: 1 regulated sites located in Rio Blanco County. Operating commercial landfills from the Colorado Department of Public Health and Environment. Retrieved September 18, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.