Lake Michigan reached record-high levels during 1985 and 1986 just 10 years after attaining its previous record highs of this century. The climate of the basin has become cloudier and cooler over the past 40 years, loading to decreased evaporation and transpiration, but the principal factor for the increased water in the basin is extremely heavy precipitation in the most recent 15 years. Precipitation in this 15-year period averaged 107 percent above the 90-year average, and since 1970 only two years have been dry and 10 have been classified as wet, or much above normal. No other prior period has experienced comparably wet conditions since quality basin-wide records began in 1895. The current record-high levels on Lake Michigan and all other Great Lakes are producing a mixture of impacts including advantages to shipping and hydropower generation and disadvantages to shorelines. Most of the impacts on Lake Michigan have been disastrous with beaches destroyed, shorelines eroded, mid near-shore stru... Abstract Lake Michigan reached record-high levels during 1985 and 1986 just 10 years after attaining its previous record highs of this century. The climate of the basin has become cloudier and cooler over the past 40 years, loading to decreased evaporation and transpiration, but the principal factor for the increased water in the basin is extremely heavy precipitation in the most recent 15 years. Precipitation in this 15-year period averaged 107 percent above the 90-year average, and since 1970 only two years have been dry and 10 have been classified as wet, or much above normal. No other prior period has experienced comparably wet conditions since quality basin-wide records began in 1895. The current record-high levels on Lake Michigan and all other Great Lakes are producing a mixture of impacts including advantages to shipping and hydropower generation and disadvantages to shorelines. Most of the impacts on Lake Michigan have been disastrous with beaches destroyed, shorelines eroded, mid near-shore stru...