The 200-acre Crego Park was closed in 1986 after industrial waste was found on the property.
The Lansing State Journal reports the city quietly reopened the park earlier this summer, but officially marked its rebirth at a ceremony Thursday.
Several current and former city officials, and more than a dozen relatives of ex-Mayor Ralph Crego took part in a ribbon-cutting.
City officials used a $500,000 grant from the Michigan Natural Resources Trust Fund and $250,000 from Lansing's parks millage fund to add a parking area, a fishing pier and a launching facility for canoes and kayaks.
Crego Park was closed after 200 drums of paint sludge and other toxic waste were found on the grounds.