R
RadonVerdict
EPA Zone 2 - Moderate Risk

Radon Levels & Zone Map in Sauk County, WI

Direct Answer for basement and lowest-level tests: Sauk County is stronger than the EPA zone label suggests. Official county data shows 5.0 pCi/L and 39.7% at or above 4.0. Do the home test, and treat a confirmed 4.0+ result as mitigation-planning territory.

Pick My Next Step I Need to Test First
Quick Read

Treat this as a test-now county

The official source signal is strong enough that a first test is the minimum; a confirmed 4.0+ result should move into cost or credit planning.

County signal

Official measured data puts this county in a high-priority testing lane.

What the number changes

2.0-3.9 pCi/L usually means retest or track. 4.0+ is where EPA action and quote planning start to matter.

Fastest next move

No reading: test first. Borderline results often need retest or long-term tracking.

Measured Radon Data

Sauk County evidence before the next step

Sauk County, WI has more than the EPA map: Wisconsin Department of Health Services exposes 1,382 reported tests, 5.0 pCi/L county average, 39.7% of reported tests at or above 4.0 pCi/L, and 107.5 pCi/L high-end signal for 1995-2016.

Source window

1995-2016

County evidence type

High measured burden

County context only; your home test controls the decision.

Primary result

5.0 pCi/L

53rd percentile in-state

4.0+ signal

39.7%

51st percentile in-state

High-end signal

107.5 pCi/L

56th percentile in-state

Official evidence dossier

Source record for Sauk County, WI

Wisconsin values are long-period ZIP-level test summaries rolled into county context, so they are useful for local burden but not a current-year snapshot.

Open source dataset

Primary public source

Official county measurements

Measurement window

1995-2016

Retrieved / checked

2026-05-05

County FIPS

55111

Evidence stack

County source

Official county measurements

Primary source used for the county evidence row.

Federal map

EPA Map of Radon Zones

Zone 2 is context, not a property result.

Housing context

US Census ACS housing context

51.7% built before 1980; 30,907 housing units.

State follow-up

State radon program

Use the state source before hiring or interpreting local rules.

Primary field

5.0 pCi/L

Median field

Not available

4.0+ field

39.7%

Sample / volume

62.8 avg/year

Metric shape

This is the most useful setup: county average, 4.0+ share, high-end readings, and 1,382 reported tests/properties can be read together instead of relying on one number.

Source limitation

Wisconsin DHS ZIP-level summaries are based on indoor radon test results from 1995-2016 and are aggregated to county by RadonVerdict using test-count weighting.

Property-level limit

Not a property-level diagnosis. The county record explains local evidence; your home's own test result controls the next decision.

County-specific interpretation

Sauk County crosses the action threshold in the official county data.

Sauk County is a test-now case because 5.0 pCi/L average, and 39.7% of reported tests at or above 4.0. In-state rank: 53rd percentile for average, and 51st percentile for 4.0+ share. No reading means get the first number; a 4.0+ home result should move straight to mitigation quotes or seller-credit math.

Real-estate use

Buyer or seller use: ask for a fresh lowest-level test before inspection deadlines, tie any 4.0+ result to a contractor quote, and do not negotiate from the county signal alone.

Sauk County should be treated as a county where a first test is urgent and a 4.0+ result should move directly into mitigation pricing or seller-credit math.

Use This Evidence

Official state path

Open the state radon program

Use state rules and local program contacts before choosing a contractor.

EPA hiring guidance

Find a qualified radon provider

EPA points homeowners to state programs and national proficiency listings.

Certified professional search

Search NRPP-certified pros

Use this after you have a valid result or need professional testing.

High-risk intent answer

Is radon bad in Sauk County?

Sauk County should be treated as a high-priority testing market because 39.7% of reported tests at or above 4.0 pCi/L, 5.0 pCi/L primary measured result, and 107.5 pCi/L high-end signal in Wisconsin Department of Health Services data. A missing home reading means test now; a 4.0+ result means mitigation pricing or seller-credit math should start.

Home result translator

Enter the result. Pick the deal side. Get the route.

Official measured data puts this county in a high-priority testing lane.

County signal

5.0 pCi/L

At or above 4.0

39.7%

Decision side

Foundation clue

No reading yet? Test first. 2.0-3.9 usually means confirm the result. 4.0+ means budget local mitigation or seller-credit math before the conversation starts.
Start with testing steps Open local cost plan

Search intent router

Start from the exact job, not another generic radon article.

Pick the situation that matches Sauk County, WI. Each route keeps the reading, deal side, or foundation clue attached so the next page answers the search instead of resetting the user.

Failed inspection

I need a repair or seller credit number

Open the local credit path with a 4.0+ buyer scenario already selected.

Open negotiation route

4.0+ pCi/L

I have a high result and need the cost path

Go straight to the county estimate, quote context, and contractor checklist.

Open cost route

2.0-3.9 pCi/L

I need to know if this number is bad

Use the level explanation first, then decide whether to retest, monitor, or price mitigation.

Open level route

No test yet

I need the first valid result

Start with kit placement, timing, closed-house conditions, and result interpretation.

Open testing route

Foundation fast lanes

Basement Slab Crawlspace

Deal fast lanes

Buyer ask Seller response

Already got a bid?

Check quote fairness
Fastest Path

Pick the situation that matches you

You should not need to read the whole guide before clicking one of these. Start with the lane that matches your current stage, then come back for the deeper reference only if you still need it.

Jump into a prefilled Sauk County action plan based on the result you already have, instead of starting from a generic cost page.

No reading yet

I have not tested yet

Do not price mitigation blind. Get the first number, then decide whether you need monitoring, quotes, or nothing at all.

Read the testing guide first Check your state radon program
2.0-3.9 pCi/L

My result is 2.0-3.9

Usually confirm the reading first. If it keeps showing up, use the county evidence and official guidance before deciding whether pricing makes sense.

Plan the confirmatory test
4.0+ pCi/L

My result is 4.0+

This is the EPA action line. Use the local cost page before calling contractors so you know the likely scope, timing, and budget.

Budget mitigation before you call contractors
Buying or selling

I am buying or selling

Turn the reading into a credit or repair number before negotiation starts. This is the faster path than arguing from a generic article.

Turn the result into a seller-credit plan

Already tested once and need the cleanest follow-up path?

Review retesting steps
Pick My Next Step

County Evidence Snapshot

Sauk County testing context

County reference page

Sauk County should be treated as a testing-priority county because the official source signal is stronger than the EPA zone label suggests. Official county data shows 5.0 pCi/L and 39.7% at or above 4.0. Use the EPA map as context, but let the home test decide mitigation or credit planning.

EPA map signal

Zone 2

County-level predicted indoor screening range, not a home-level test result.

Housing base

30,907

68th percentile among 72 WI counties with data.

Older housing share

51.7%

88th percentile in-state; older homes often need clearer test placement decisions.

Median home value

$227,500

Used as context for whether mitigation is a small maintenance item or a negotiation issue.

Measured Radon Data

Wisconsin Department of Health Services Indoor Radon Test Results

1995-2016

Average result

5.0 pCi/L

At or above 4.0

39.7%

Maximum reported

107.5 pCi/L

Avg. tests/year

62.8

At or above 2.0 pCi/L: 68.9%.

Wisconsin DHS ZIP-level summaries are based on indoor radon test results from 1995-2016 and are aggregated to county by RadonVerdict using test-count weighting.

County evidence interpretation

High measured burden

Source-backed context Not a home-specific result

Primary result rank

53rd percentile

5.0 pCi/L

4.0+ rank

51st percentile

39.7% at or above 4.0

High-end rank

56th percentile

107.5 pCi/L

Test volume rank

67th percentile

62.8 avg/year

How to use this county data

Data source

Official county measurements

Wisconsin values are long-period ZIP-level test summaries rolled into county context, so they are useful for local burden but not a current-year snapshot.

What the numbers show

Fuller county picture

This is the most useful setup: county average, 4.0+ share, high-end readings, and 1,382 reported tests/properties can be read together instead of relying on one number.

Nearby comparison

Nearby comparison: Closest counties by share of tests at or above 4.0 pCi/L: Oconto County (39.3%) is just lower, and Eau Claire County (40.9%) is just higher.

How this helps

Use this to decide how urgently to test, retest, or plan mitigation after a 4.0+ result.

What the data says

Sauk County, WI is measurement-backed for 1995-2016. The measured average is 5.0 pCi/L, and 39.7% of reported results are at or above 4.0 pCi/L. The high-end signal reaches 107.5 pCi/L.

Sauk County, WI sits at the 53rd percentile for measured average, 51st percentile for 4.0+ share, 56th percentile for high-end readings, and 67th percentile for test volume among 72 measured counties in the state. Closest counties by county average: Ozaukee County (5.0 pCi/L) is just lower, and Milwaukee County (5.1 pCi/L) is just higher.

What to do with it

Sauk County should be treated as a county where a first test is urgent and a 4.0+ result should move directly into mitigation pricing or seller-credit math.

Retest trigger: a 2.0-3.9 pCi/L home result should be confirmed here because 5.0 pCi/L average, and 39.7% of reported tests at or above 4.0 keeps the county from being a dismiss-it signal.

Source-backed context from Wisconsin Department of Health Services based on about 1,382 reported tests/properties plus comparable county-level measurement fields.

No reading yet

No reading yet: run a short-term test now, then confirm or price mitigation quickly if the result is elevated.

2.0-3.9 result

2.0-3.9 pCi/L: retest or track longer-term rather than dismissing the result, because the county distribution has meaningful elevated readings.

4.0+ result

4.0+ pCi/L: use the result for mitigation quotes, repair scope, or seller-credit negotiation; the county signal is no longer the deciding input.

Source hierarchy: Wisconsin Department of Health Services is used for this county, with EPA zone and Census housing data kept as supporting context. Wisconsin values are long-period ZIP-level test summaries rolled into county context, so they are useful for local burden but not a current-year snapshot.

Direct Answer

Is radon bad in Sauk County?

Sauk County should be treated as a high-priority testing market because 39.7% of reported tests at or above 4.0 pCi/L, 5.0 pCi/L primary measured result, and 107.5 pCi/L high-end signal in Wisconsin Department of Health Services data. A missing home reading means test now; a 4.0+ result means mitigation pricing or seller-credit math should start.

Evidence Value
Area Sauk County, WI
EPA Zone Zone 2
Primary Recommendation Perform direct radon testing in the lowest livable level

Sources

Your Radon Reading

Enter your home's measured level; the starting value is only a planning example until you have your own result.

3.0 pCi/L
0 2.7 WHO 4.0 EPA 10 20+

Elevated - Consider Action

Your reading is below the US EPA action level (4.0 pCi/L), but this range still warrants follow-up testing. The World Health Organization uses 2.7 pCi/L as a tighter reference point.

If this was just a one-time snapshot, confirm it with another test or with longer tracking. If this level persists, planning mitigation is reasonable, especially for homes with frequent basement use, children, or pending real-estate transactions. Scroll down to see your estimated cost.

Review confirmatory testing Compare short-term vs long-term testing
pCi/L

Understanding Radon Levels: Complete Reference

<2.0

Below 2.0 pCi/L - Lower Concern, Keep Testing

Below both the EPA (4.0) and WHO (2.7) action reference levels. This usually means mitigation is not the next immediate step after a confirmed result. The average outdoor radon level is approximately 0.4 pCi/L, and there is no known risk-free indoor level. Periodic testing is still recommended because levels can change over time due to seasonal variations, changes in home ventilation, or foundation settling.

2.0
-4.0

2.0 - 4.0 pCi/L - Elevated, Consider Action

Exceeds the World Health Organization's reference level of 2.7 pCi/L but falls below the US EPA action threshold. The EPA states that homeowners should "consider fixing" homes in this range, especially if the home has a basement used as living space, if children are present, or in connection with a real estate transaction. Practical next step: run a confirmatory long-term test, then compare mitigation quotes if levels remain elevated.

4.0
-8.0

4.0 - 8.0 pCi/L - Action Recommended

Exceeds the EPA action level of 4.0 pCi/L. The EPA and Surgeon General strongly recommend mitigation within a few months. At this level, prioritize confirmatory testing and contractor planning. Standard sub-slab depressurization systems typically reduce indoor levels by 80-99%.

8.0+

Above 8.0 pCi/L - Urgent Action Required

At these levels, the EPA recommends expedited mitigation - ideally within weeks, not months. Occupants should minimize time in lower-level rooms until the system is installed. Use a certified mitigator and request priority scheduling to shorten high-exposure time. Many mitigators offer priority scheduling for homes above 8.0 pCi/L.

Why Radon is a Testing Priority in Sauk County

The EPA map is only the starting layer for Sauk County. Official county data shows 5.0 pCi/L and 39.7% at or above 4.0. That source-backed signal is why the practical move is testing or retesting before treating the county as low urgency.

This still is not a diagnosis for any single home. Foundation type, lowest-level use, pressure differences, and small geological changes can move one house above or below the county pattern.

If you do not have a reading yet, start with a short-term test in the lowest lived-in level. If the result is 2.0-3.9 pCi/L, confirm it; if it is 4.0+ pCi/L, move into mitigation pricing or seller-credit planning.

Radon & Health: What the Science Says

#2
Leading cause of
lung cancer
21K
US deaths per year
from radon
1 in 15
US homes above
4.0 pCi/L

Radon is a Class A carcinogen - the same classification as asbestos and tobacco smoke. The National Academy of Sciences estimates that radon causes approximately 21,000 lung cancer deaths annually in the United States, making it the leading environmental cause of cancer death.

Unlike smoking, radon exposure is involuntary and often invisible. There is no safe level of radon - risk increases linearly with exposure. The good news: radon mitigation systems are highly effective, typically reducing indoor levels by 80-99% within hours of activation.

Source: US Environmental Protection Agency, "A Citizen's Guide to Radon" (EPA 402/K-12/002). National Academy of Sciences, Biological Effects of Ionizing Radiation (BEIR VI) Report, 1999.

Step 1: Test Your Home

Testing is the only way to know your home's radon level. Zone and county data tell you the regional signal, but your home could be significantly higher or lower than the countywide pattern. Start with a valid test setup before using any cost path.

Testing first
Open the home testing guide
Short-term, long-term, retest, and real-estate setup
Need the official path?

State radon programs and EPA provider guidance are the right reference before hiring or confirming local requirements.

Open the state radon program

Already Know Your Level?

If your test shows 4.0 pCi/L or higher, get an itemized cost estimate specific to Sauk County - including regional labor rates and permit requirements.

Get Mitigation Cost Estimate ->

WI Radon Regulations

!
Seller Disclosure

Wisconsin requires sellers to complete a Real Estate Condition Report that includes known radon test results and environmental hazards.

-
Professional Licensing

Wisconsin does not require specific radon licensing. NRPP or AARST certification is recommended.

Official state radon program

How to Test for Radon in Sauk County

1

Buy a Test Kit

Purchase a short-term charcoal test kit online or from a local hardware store. Cost: $15-$30. Place it in the lowest livable level of your home.

2

Wait 2-7 Days

Keep doors and windows closed (except normal entry/exit) during the test period. Avoid running whole-house fans. Mail the kit to the lab provided.

3

Read Your Results

If results are below 4.0 pCi/L, re-test every 2 years or use a monitor for ongoing tracking. If above 4.0, use our cost calculator to see mitigation options.

Related Radon Resources for Sauk County

Radon Mitigation Cost Guide Use the national cost model before the county cost page is submitted for indexing. Radon Levels: 2.0 vs 4.0 vs 8.0 Understand what the numbers mean before comparing local next steps. WI Radon Levels Hub Compare measured 4.0+ share, high-end readings, and official source coverage. How to Test for Radon Closed-house protocol, kit placement, and retest intervals. DIY vs Professional Mitigation Decision framework for moderate-risk homes. Who Pays: Buyer or Seller? Use radon cost context for credits, repairs, and closing negotiation. Seller Credit Calculator Estimate a repair or credit ask without sending crawlers to a noindex county calculator. Measured-risk peer: Outagamie County Compare against a county with 49.8% of reported tests at or above 4.0 pCi/L and 5.0 pCi/L primary result. Measured-risk peer: Kenosha County Compare against a county with 50.1% of reported tests at or above 4.0 pCi/L and 5.3 pCi/L primary result. Manitowoc County Levels Compare against a county with 35.7% of reported tests at or above 4.0 pCi/L and 4.0 pCi/L primary result.

Explore Other WI Counties

Outagamie Zone 2 - Moderate Kenosha Zone 2 - Moderate Manitowoc Zone 2 - Moderate Jefferson Zone 1 - High Risk Brown Zone 2 - Moderate La Crosse Zone 2 - Moderate

Official State Resource

Wisconsin radon program and rules

Use the state program link to verify local radon guidance, disclosure language, and contractor credential expectations before you act on an estimate.

Open official WI resource

Disclosure rule tracked

Wisconsin requires sellers to complete a Real Estate Condition Report that includes known radon test results and environmental hazards.

Credential note

Wisconsin does not require specific radon licensing. NRPP or AARST certification is recommended.

Sources & Methodology

Radon zone classifications for Sauk County are sourced from the EPA's Map of Radon Zones, which uses geological surveys, indoor radon measurements, and soil permeability data to assign each county a risk tier.

Disclaimer: Zone data represents county-level screening ranges and cannot predict the radon level in any specific home. Testing is the only reliable method to determine your home's radon concentration. This content is for informational purposes and is not medical advice.

Content review: Source-level retrieval dates

Editorial and Data Transparency

Author
RadonVerdict Data Team (Public Data and Cost Modeling)
Content Review
Source-level dates shown below
Data Retrieved At
2026-02-24

Primary Sources