Over the past decade harmful algal blooms (HABs) have become a nationwide environmental concern. HABs are likely to increase in frequency and intensity due to rising summer temperatures caused by climate change and higher nutrient enrichment from increased urbanization. Policymakers need information on the economic costs of HABs to design optimal management policies in the face of limited budgets. Using a detailed, multi-lake hedonic analysis across 6 Ohio counties between 2009 and 2015 we show capitalization losses associated with near lake homes between 12% and 17% rising to over 30% for lake adjacent homes. In the case of Grand Lake Saint Marys, we find capitalization losses exceeding $48 million for near lake homes which dwarfs the State of Ohio’s cleanup expenditure of $26 million.