The Ohio Environmental Protection Agency (OEPA) Source Water Assessment and Protection Program has invested millions of dollars to help create and implement protection plans for sources of drinking water that serve over 5.1 million people across the state.  

Tracking spreadsheets listing every municipal and non-municipal public water system with an OEPA-endorsed protection plan or checklist plan are regularly updated online. As of October 2018, OEPA has endorsed 231 municipal plans covering over 4.8 million people, and just over 1,500 checklist plans covering an additional 264,000 people. These spreadsheets also break down the population served by individual systems and provide the date that each plan was endorsed.