If the King County Parks levy doesn’t pass on the Aug. 6 primary-election ballot, popular trails and parks will close, county officials say.

The county parks system, which includes 200 parks, 175 miles of trails and 26,000 acres of open space, depends on the six-year tax levy for 70 percent of its operating funds. County parks generate the rest of their operating budget through ballfield rentals and commercial ventures, like having Cirque du Soleil at Marymoor Park.

The proposed levy would fund maintenance at Marymoor, Cougar Mountain and other big regional parks, as well as smaller parks in cities and unincorporated King County. It would fund new purchases of open space and development of new trails, including connecting an east-west trail in South King County.

About seven percent of the money goes toward the Woodland Park Zoo in Seattle.

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King County cut county parks and recreation out of its general fund in 2002, during a financial crisis. In 2004, voters approved an initial parks levy, which was renewed in 2007.

“There really is no alternative to it. No viable one,” said Charles Royer, a former mayor of Seattle who is on the committee to pass the levy.

King County residents currently pay 13.4 cents per $1,000 of home value — about $40 a year for the owner of a $300,000 home. The proposed increase is to 18.77 cents, to $56 a year for the owner of the same home.

The levy was split into two halves in 2007 — maintenance and operations, and, separately, new acquisitions. Both passed with about 60 percent of the vote.

This year’s ballots are due Aug. 6. There has been some controversy over the size of the levy and whether the county should buy more parkland when it has trouble maintaining what it owns.

But even Metropolitan King County Councilmember Kathy Lambert, who opposed the structure of the levy, plans to vote for it.

“It would be absolutely horrible to have to close parks,” she said.

Emily Heffter: 206-464-8246 or eheffter@seattletimes.com. On Twitter: @EmilyHeffter