A measure to use $23 million in bonds to buy and preserve an undeveloped parcel of open space in Tiburon was headed for approval by a comfortable margin, according to updated election figures released this week.

Measure M, which authorizes the purchase of the 110-acre “Martha Property” on the Tiburon Peninsula, had 78.67 percent of the vote as of Monday, according to the Marin County Registrar of Voters website.

It requires a two-thirds majority to pass.

A campaign logo for the Yes on M campaign. Supporters of the measure are celebrating the apparent success of their effort to purchase the 110-acre “Martha Property” on the Tiburon Peninsula. (Image courtesy of Tiburon Open Space Committee/Facebook)

“I am so happy that all the hard work by so many volunteers has paid off,” said Jerry Riesssen, president of the group Tiburon Open Space.

“The community support is fantastic,” Riessen said. “We await the final results but it looks very encouraging.”

In addition to the bond, the measure also creates an annual special tax of $335, which will increase by 2 percent every year until the bonds are repaid, for property owners in Tiburon east of Trestle Glen Boulevard and Belvedere.

The nonprofit Trust for Public Land will buy the land for $42 million and then sell it to Marin County for $26 million.

Additional funds will come from past bond measures and Measure A, which was approved by voters in June and raises money for parks and open spaces in Marin County.

The Marin County Open Space District will issue the bonds.