The beginning of the modern environmental movement can be traced to multiple events, but one of the most significant is the publication of "Silent Spring" by Rachel Carson in 1962. This book raised public awareness about the dangers of pesticides and environmental pollution, leading to increased advocacy for environmental protection and regulations.
While the other events you mentioned, like the creation of the EPA in 1970, the Cuyahoga River fire, and the California oil spill of 1969, also played important roles in the environmental movement, "Silent Spring" is often credited for sparking widespread concern and action regarding environmental issues.