Allen County, Indiana: drinking water report. Allen County is the second-most populous county in Indiana, with Fort Wayne and about 385,000 residents.
Allen County is the second-most populous county in Indiana, with Fort Wayne and about 385,000 residents. Fort Wayne City Utilities draws water from the St. Joseph River and three major reservoirs. The county sits at the confluence of three rivers – the St. Joseph, St. Marys, and Maumee – and the flat agricultural landscape surrounding the city channels runoff directly into these waterways.
Nutrient loading drives the primary water quality concern in Allen County. The Maumee River watershed, which drains much of northwestern Ohio and northeastern Indiana, is the largest single contributor of phosphorus to Lake Erie. According to USGS monitoring data from 2024, the St. Marys River at the Fort Wayne gauge showed total phosphorus concentrations averaging 0.18 mg/L – well above the 0.07 mg/L threshold associated with algal bloom risk.
For drinking water specifically, the EPA's UCMR5 testing detected PFAS compounds in the Fort Wayne system. The former Baer Field Air National Guard Base (now Fort Wayne International Airport) used AFFF firefighting foam during military operations. Indiana has no state-level PFAS standard, so federal MCLs are the applicable benchmark.
Fort Wayne's water treatment plant manages most contaminants effectively, but the combination of agricultural runoff and military-related PFAS means emerging compounds deserve attention. Summer months, when runoff peaks and algal activity increases, tend to produce the most challenging raw water quality.
Start by checking your water for the latest results at your address. A carbon block filter handles taste and disinfection byproducts, while reverse osmosis adds PFAS protection. Our water filter guide breaks down which systems address which contaminants. Pull your detailed report for seasonal trends, and visit our Indiana page for the broader state picture.