Lake County, Ohio: drinking water report. Lake County sits along Lake Erie northeast of Cleveland, with about 230,000 residents.
Lake County sits along Lake Erie northeast of Cleveland, with about 230,000 residents. The Mentor, Painesville, and Willoughby areas draw from Lake Erie through the Lake County Water Department and smaller municipal systems. The county's shoreline location provides access to Great Lakes water, but it also means exposure to the lake's documented quality challenges – seasonal algal blooms, legacy industrial contamination, and agricultural nutrient loading from tributaries.
Lake Erie's western basin regularly produces harmful algal blooms driven by phosphorus runoff from Ohio and Indiana farmland. While Lake County sits in the eastern basin where blooms are less frequent, microcystin – the toxin produced by cyanobacteria – has been detected at the county's intake during late summer. According to the Ohio EPA's 2024 drinking water surveillance report, Lake County's treatment plants successfully remove microcystin below the 1.0 ug/L standard, but raw water levels reached 2.8 ug/L during August 2024.
PFAS compounds have also been found in the Lake Erie supply. The EPA's UCMR5 data showed detections across multiple Lake County systems. Industrial legacy compounds from the nearby Painesville Township Industrial Park and former Diamond Shamrock chemical operations add TCE and other solvents to the groundwater profile.
The Lake Erie supply is treated effectively for most regulated contaminants, but late summer algal toxin risk and year-round trace PFAS exposure are factors worth addressing at the household level.
Check your water for current monitoring results. A quality carbon block filter handles microcystin and disinfection byproducts, while reverse osmosis adds PFAS protection. Our water filter guide covers systems suited to Great Lakes water. Pull your detailed report for seasonal data, and visit our Ohio page for statewide context.
Drinking water is one exposure route. These federal datasets also cover Lake County, OH.
The EPA places Lake County, OH in Zone 2 - a moderate-risk category, with a predicted average indoor radon level between 2 and 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
65% of homes in Lake County, OH were built before 1980, and 14% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Lake County, OH averages 8 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide