Chlorate in Michigan Drinking Water
Ranked by max chlorate detected (µg/L) · UCMR 3 data (2013–2015) · Data from EPA SDWIS & UCMR
Chlorate in Michigan: what the data shows
Michigan has 54 cities with chlorate data from the EPA's UCMR 3 program (2013–2015). Chlorate exceeded the 210 µg/L EPA lifetime health advisory in 32 of those cities. The state average max detected level is 424.8 µg/L. Chlorate is a disinfection byproduct that forms when chlorine dioxide or hypochlorite solutions are used to disinfect drinking water. It is most common in systems that use chlorine dioxide for taste-and-odor control or that store hypochlorite for extended periods. There is no federal MCL — the EPA lifetime health advisory is 210 µg/L. Chlorate can interfere with thyroid function by blocking iodide uptake, an effect of particular concern for pregnant women, infants, and people with thyroid conditions. Reverse osmosis and ion exchange (anion-specific) are effective at removing chlorate; standard activated carbon filters provide only modest reduction.
Cities exceeding 210 µg/L EPA lifetime HA (no MCL)
Chlorate data across Michigan
Each dot is a city with UCMR 3 chlorate testing data. Cities where chlorate exceeds the 210 µg/L EPA lifetime health advisory are highlighted. Size reflects population served.
Top 10 cities by chlorate level in Michigan
Highest Chlorate levels (µg/L)
All Michigan cities ranked by chlorate level
| # | City | Level | Level | Over HA? | Violations | Grade |
|---|---|---|---|---|---|---|
| 1 | Portage | 4256.1 µg/L | Over HA | 1 | B+ | |
| 2 | Clarkston | 2160.0 µg/L | Over HA | 10 | B+ | |
| 3 | Benton Harbor | 1500.0 µg/L | Over HA | 16 | D+ | |
| 4 | Bloomfield Township | 992.0 µg/L | Over HA | 0 | A+ | |
| 5 | Monroe | 976.0 µg/L | Over HA | 6 | C | |
| 6 | Mount Clemens | 797.0 µg/L | Over HA | 3 | B+ | |
| 7 | Mount Pleasant | 770.0 µg/L | Over HA | 1 | B+ | |
| 8 | Mt Pleasant | 580.0 µg/L | Over HA | 0 | C | |
| 9 | New Lothrop | 568.7 µg/L | Over HA | 1 | A- | |
| 10 | Brighton | 544.8 µg/L | Over HA | 25 | F | |
| 11 | Fenton | 445.1 µg/L | Over HA | 5 | D | |
| 12 | Auburn Hills | 442.2 µg/L | Over HA | 1 | B+ | |
| 13 | Traverse City | 440.0 µg/L | Over HA | 12 | D+ | |
| 14 | Ann Arbor | 400.0 µg/L | Over HA | 39 | D+ | |
| 15 | Grand Haven | 350.0 µg/L | Over HA | 1 | A- | |
| 16 | Wyandotte | 340.5 µg/L | Over HA | 0 | B+ | |
| 17 | Norton Shores | 332.0 µg/L | Over HA | 0 | A | |
| 18 | Lansing | 330.0 µg/L | Over HA | 13 | C- | |
| 19 | Saline | 322.3 µg/L | Over HA | 0 | B+ | |
| 20 | Fort Gratiot | 320.0 µg/L | Over HA | 1 | A | |
| 21 | Muskegon Heights | 319.0 µg/L | Over HA | 2 | B+ | |
| 22 | Adrian | 300.0 µg/L | Over HA | 46 | F | |
| 23 | Holland | 288.0 µg/L | Over HA | 20 | B- | |
| 24 | New Baltimore | 288.0 µg/L | Over HA | 1 | A | |
| 25 | Port Huron | 284.7 µg/L | Over HA | 0 | A- | |
| 26 | Corunna | 270.0 µg/L | Over HA | 0 | A | |
| 27 | Roosevelt Park | 266.0 µg/L | Over HA | 0 | A | |
| 28 | Muskgon | 238.9 µg/L | Over HA | 1 | A | |
| 29 | Bad Axe | 229.0 µg/L | Over HA | 3 | A | |
| 30 | Grandville | 225.1 µg/L | Over HA | 0 | A- | |
| 31 | Muskegon | 225.0 µg/L | Over HA | 3 | B | |
| 32 | Kentwood | 214.8 µg/L | Over HA | 3 | B | |
| 33 | Ionia | 210.0 µg/L | No | 3 | A | |
| 34 | Owosso | 196.0 µg/L | No | 15 | C+ | |
| 35 | Waterford | 190.0 µg/L | No | 11 | B | |
| 36 | Allendale | 190.0 µg/L | No | 0 | A- | |
| 37 | East Lansing | 180.0 µg/L | No | 12 | F | |
| 38 | Okemos | 180.0 µg/L | No | 10 | B- | |
| 39 | Alpena | 180.0 µg/L | No | 14 | C- | |
| 40 | Byron Center | 170.3 µg/L | No | 0 | A+ | |
| 41 | Jenison | 166.0 µg/L | No | 0 | A- | |
| 42 | Manistee | 160.7 µg/L | No | 3 | A- | |
| 43 | Flint | 150.0 µg/L | No | 29 | D | |
| 44 | Sturgis | 150.0 µg/L | No | 1 | A | |
| 45 | Bridgeport | 148.5 µg/L | No | 0 | A+ | |
| 46 | Grand Rapids | 130.0 µg/L | No | 10 | B- | |
| 47 | Saginaw | 114.8 µg/L | No | 3 | A- | |
| 48 | Bay City | 107.6 µg/L | No | 20 | B | |
| 49 | East Grand Rapids | 102.0 µg/L | No | 0 | B+ | |
| 50 | Big Rapids | 58.0 µg/L | No | 3 | B+ | |
| 51 | South Lyon | 44.0 µg/L | No | 1 | B | |
| 52 | Ypsilanti | 41.0 µg/L | No | 5 | B+ | |
| 53 | Marquette | 28.3 µg/L | No | 4 | F | |
| 54 | Southgate | 27.8 µg/L | No | 0 | A- |
Frequently asked questions about chlorate in Michigan
Is chlorate in Michigan tap water dangerous?
Chlorate has no federal MCL. The EPA lifetime health advisory is 210 µg/L. 32 cities in Michigan exceed this level. Chlorate can interfere with thyroid iodide uptake, which is a particular concern for infants, pregnant women, and people with hypothyroidism.
Where does chlorate in Michigan water come from?
Chlorate is a byproduct of chlorine-based disinfectants — particularly chlorine dioxide and hypochlorite (bleach) solutions. Levels tend to be higher in systems that use chlorine dioxide for taste-and-odor treatment or store sodium hypochlorite at high concentrations or for long periods. Levels vary seasonally with disinfectant use.
How can I reduce chlorate exposure?
Reverse osmosis is the most effective home treatment for chlorate, typically removing 80–95%. Anion exchange systems also work but require regeneration. Standard activated carbon filters provide only limited chlorate reduction. Boiling does NOT remove chlorate.