The site of the contamination is the 160-acre BF Goodrich industrial facility which produces fireworks, munitions and rocket motors.
Emhart Industries and the cities of Rialto and Colton are among the parties paying up.
Emhart will spend an estimated $43 million over the next 30 years for the first part of the cleanup.
Rialto and Colton will pay more than $4 million toward the remainder.
