Sonoma's city attorney on Monday released a summary of a proposed ballot measure that would limit hotel development in the city, including the controversial Chateau Sonoma & Spa proposed near the Plaza.

Proponents of the measure can begin circulating petitions after they have advertised their intention to do so in a local newspaper.

To qualify for a special election, petitioners must gather 1,017 signatures, or 15 percent of the city's 6,782 registered voters.

The ballot measure would cap the number of rooms at a hotel at 25 unless the city's hotel occupancy rate over the previous calendar year exceeded 80 percent. In 2012, the rate was just under 65 percent. The limit would cover both expansion and new development.

In addition, the Planning Commission would have to determine that a qualifying project does not "adversely affect the historic, small town character of Sonoma" prior to issuing a use permit. That approval could be appealed to the City Council, but would require a four-fifth's vote for the project to go forward.

The Preserving Sonoma Committee, which includes former Mayor Larry Barnett and several political activists, contends that the measure is necessary to protect the city's quality of life from what the group considers to be major hotel development.

Barnett has said the measure is not aimed at Chateau Sonoma, which in its most recent incarnation included plans for a three-story, 59-room hotel, with two restaurants, a health club and spa, event center and 2,800 square feet of retail space.

However, the project is the only one currently in the city's planning process. It is proposed by Darius Anderson, a Sacramento lobbyist and principal of Sonoma Media Investments, which owns The Press Democrat.

Anderson has said that he has revised the plans to reflect community concerns, but has declined to provide details of the changes. The revised plan has not yet been submitted to City Hall.

If the measure qualifies for the ballot, a special election could be held in the fall. City officials have said the cost of such an election would be about $30,000.

The City Council would have the option of avoiding an election by adopting the proposal as written.