SAN DIEGO -- San Diego voters approved a ballot measure requiring more revenue generated by leases at Mission Bay Park to be used to maintain the recreation area, according to election results released Wednesday.

With all of the precincts counted, 66.5 percent, or 235,563 voters, were in favor of Proposition C, while 33.5 percent, or 118,682 voters, were opposed.

Proposition C changes the city charter, requiring that 75 percent of lease revenues that exceed $23 million be spent on improvements to Mission Bay Park. The threshold would drop to $20 million after five years.

The remaining 25 percent of revenue would be spent on regional parks, including Chollas Lake, Balboa, Mission Trails, Otay River Valley, Presidio, San Diego River and various open spaces and beaches.

The measure expires after 30 years.

Only about 8 percent of the revenue generated from hotels, SeaWorld and other lease holders goes to Mission Bay Park. Much of that money is now diverted to the city's general fund.

Proposition C is expected to raise $5.3 million for Mission Bay Park in 2010 and $11.7 million by 2015. Other regional parks in San Diego would get between $2.5 million and $3.9 million annually over the same period.