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Counties → Wisconsin

Jefferson County, Wisconsin

SDWIS compliance plate

Sheet WI055 · Jefferson County 194 sys · 2,740 viol · #623/3254

VIOL-SEVERE · HEALTH-MID · RANK-TOP · PHOTO-FINISH · PFAS-LOW · SRC-GW · SYS-LARGE · BOOK-FULL

  • VIOL-SEVERE 68.6% flagged
  • HEALTH-MID 39.1% health
  • RANK-TOP #623/3254
  • PHOTO-FINISH ±0.3 pp
  • PFAS-LOW 16.7% detect
  • SRC-GW GW lead 100%
  • SYS-LARGE 194 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Sawyer County ( -0.3 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Jefferson County ranks #623 of 3,254 counties by people served, and #17 of 71 counties in Wisconsin. See methodology · corpus placement.

Jefferson County standing, lower-flagged corpus third

Flagged-system rate 68.6% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 39.1% is health-based share above the upper third (> 24.5%) . UCMR5 detect rate 16.7% is UCMR5 detect rate in the tested-pool middle third (≤ 33.3%) . Population served ranks #623 of 3,254 · #17 of 71 in Wisconsin.

Flagged-rate neighbourhood around Jefferson County

Lowest/highest poles plus in-state counties nearest Jefferson County on % of SDWIS systems with ≥1 violation. Full ladder: /counties.

0% 20% 40% 60% 80% 100% Bayfield · lowest Lincoln · near Jefferson · this county Milwaukee · highest 52.1% 67.7% 68% 68.2% 68.6% 69% 95.3%

Source: EPA SDWIS (county aggregates) As of 2026-05-15

Water Systems

System Name Population Violations PFAS
Watertown Waterworks 23,945 35 Clean
Fort Atkinson Waterworks 12,390 30 Clean
Jefferson Waterworks 7,926 61 Clean
Lake Mills Waterworks 6,211 159 Clean
Waterloo Waterworks 3,520 50 Clean
Johnson Creek Waterworks 3,318 121 -
WI DOT Rest Area 14 Aztalan 3,204 47 -
WI DOT Rest Area 13 Aztalan 3,004 72 -
Palmyra Waterworks 1,756 57 Detected
River Bend Resort 1,520 5 -
T&s Buss Inc 864 0 -
Concord General Store 807 4 -
Olin-Sang-Ruby Union Institute - Main System 704 47 -
Olin-Sang-Ruby Union Institute - Bath House 700 0 -
Olin-Sang-Ruby Union Institute - Dining Hall 700 29 -
Lake Mills Travel Plaza 662 6 -
Hubbleton Brewing Taproom & Grill 610 6 -
Autumn Ridge Water System LLC 575 32 -
Faith Community Church/School 550 28 -
Spacious Acres Mobile Home Community 525 8 -
Tremain Mobile Home Park 475 36 -
Crawfish Junction 412 0 -
St Pauls Ev Lutheran Church 406 19 -
Station Ixonia 360 0 -
Silo Ridge Clubhouse 322 0 -
Ixonia Elementary School 310 108 -
Rons Market 308 0 -
Wishing Well RV Resort Lodge Well System 303 11 -
Grace Lutheran Church 302 6 -
First Congreg United Ch of Christ/Gingerbread Preschool 280 6 -
North Shore Chophouse 257 4 -
Wayside Tavern 251 18 -
Bark River Campground - Main Building System 250 2 -
WI DNR Glacial Drumlin Trail Sullivan Rst AR 250 107 -
Sullivan Elementary School 233 16 -
Immanuel Lutheran Church 231 3 -
Pernats of Ixonia 227 0 -
Rosy Lane Holsteins Farm Office 221 0 -
Lake Ripley Country Club - Clubhouse 208 8 -
Edge of Town Cafe 206 6 -
Lake Ripley Family Restaurant 206 0 -
Sullivan Saloon 205 0 -
Real Maccoy The 205 5 -
Koshkonong Mounds Country Club 204 3 -
Rome Riverside Campground 202 9 -
Bark River Lanes 201 27 -
Aztalan Inn 200 7 -
Wishing Well RV Resort Deep Well Syst 200 14 -
Von Loppys 177 3 -
Lakewood Village 160 13 -

Compare beyond Wisconsin

Lower-flagged peers for Jefferson County

Cross-state counties nearest Jefferson County on flagged-system share (68.6%) and cumulative violation count (2,740). In-state neighbours stay on the compliance plate above.

Similar flagged-system rate

Nearest cross-state counties by % of SDWIS systems with at least one violation on record.

4 peers

Similar violation load

Nearest cross-state counties by cumulative SDWIS violation count (all systems in the county).

4 peers

Read our methodology · Check your water system - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.