In the latest in a series of policy proposals from Philadelphia mayoral candidates, former Councilman Michael Nutter yesterday unveiled a plan to improve Fairmount Park and boost City Hall's environmental credentials.

Nutter, one of five major candidates in the city's May 15 Democratic mayoral primary, called for building environmental concerns into the structure of governance by creating a "sustainability cabinet" that would write green requirements into new building, zoning and contracting policies.

And Nutter also vowed reforms to the city's foremost chunk of open space, Fairmount Park, which sits largely in his former City Council district and has been the subject of recent political wrangling.

Nutter wants to change the makeup of the Park Commission, whose members are currently picked by the city's Common Pleas judges. Nutter said the process is political and often leads to appointees whose only qualifications are that "they liked to go to the park when they were kids."

Instead, he called for a system where commissioners are nominated by the mayor and confirmed by City Council - but only after having their credentials vetted by a nominating committee.

Nutter also said he would work to raise the park's annual budget from $13 million to $30 million by letting the park hold on to new user fees and concession charges, by applying for new environmental grants, and by creating a transparent fund to help lure private and philanthropic gifts for the park.

Donors, he said, would view the fund as a "lock box" immune from the other political needs of City Hall.

Nutter said the proposed new user fees would not mean boosting charges on softball players or picnickers. Rather, he said, he hoped to build in new amenities such as roller-skate rental or bicycle rental and storage, and then make sure that all of the proceeds wind up in the park's coffers.

One possible place to increase revenues, according to Nutter's campaign: the park's Dell East Amphitheater, where in recent summers the vast majority of concertgoers have managed to avoid paying for their concert tickets, costing the city hundreds of thousands of dollars.

But the most generous source for Dell freebies, though, was one Nutter might remember: City Council offices. Council members - including, until last summer, Nutter himself - receive 102 free tickets, with an average price of $18, to each Dell concert, to hand out as they please.

Contact staff writer Michael Currie Schaffer at 215-854-4565 or mcschaffer@phillynews.com.