A fight between taxpayer advocates and proponents of an open space district in Napa County is headed to court Monday.

The skirmish is over the proposed Nov. 7 ballot argument opposing Measure I. The measure, if passed by voters, would create a parks and open space district encompassing all of Napa County.

Nan Vaaler, former Napa City-County Library director, filed suit against the Napa County Registrar of Voters, charging the ballot statement filed Measure I opponents is false and misleading. Vaaler is seeking a judgment that would block many of the statements from inclusion in the voter's pamphlet.

The Napa Valley Land Stewards Alliance and two Napa County Planning Commissioners, Rich Jager and Terry Scott, said in their ballot statement that the open space measure would create a "special interest bureaucracy that will suck up millions of tax dollars."

Opponents also say Measure I would give the open space district the ability to solicit property owners -- via a mail-in ballot -- for a property assessment tax hike to provide revenues. If enacted, they contend, this would circumvent a two-thirds voter majority requirement for property tax increases, put in place by Proposition 13.

Proponents say the measure is solely a question of forming an open space district and electing its officers, not levying assessments or bonds. The Napa County Board of Supervisors -- by a 3-2 vote -- approved the measure to go on the Nov. 7 ballot, knowing the agency would have about a quarter of a million dollars already budgeted. Supervisors Bill Dodd and Harold Moskowite are opposed to the measure.

In court papers, Vaaler took issue with most of the opposition ballot statement, saying the charges were not relevant to Measure I. Vaaler asked the court to throw out the statements, citing case law that requires ballot arguments to be germane to the measure in question.

An impartial analysis of Measure I approved the Local Agency Formation Commission of Napa County said if formed, the open space district would be financed at a level determined by the board of supervisors. But the analysis also said the district could get funding by collecting assessments and service fees, among other methods.

Still, it said Measure I does not specifically authorize the district to collect any assessments or bonds.

Michael Haley, a member of the Land Stewards, said his group is fighting Measure I in part because they feel mail-in property assessment ballots are ignored by most property owners.

Lester Hardy, a Napa attorney who is representing Vaaler, said the conflict over the ballot measures could prove significant in each sides' campaign on Measure I.

"For many voters, perhaps most voters, the ballot measure arguments are all they will read about it," he said.