The Sonoma-Marin commute rail district is negotiating with the Sonoma County Water Agency to purchase land near the county's airport as a potential site for an operations and maintenance facility.

Rail officials have been looking for a site to build a $20 million center where trains will be stored and serviced nightly and where computerized train controls can be located.

The 6.6 acres of vacant water-agency land are on the south side of Airport Boulevard along the rails where trains eventually would run between downtown Santa Rosa and Windsor.

The negotiations are to be discussed in closed sessions by the Sonoma County supervisors on Tuesday and by the board of the Sonoma-Marin Area Rail District on Wednesday.

SMART General Manager Farhad Mansourian said the district is still in negotiations with two other property owners on sites that could house the facility.

SMART Chairwoman Valerie Brown, who is also a Sonoma County supervisor, said she could not discuss items scheduled for closed session, but acknowledged SMART's search for an operations site.

"We are negotiating for an O&M (operations and maintenance) property. We have been looking for quite some time," Brown said. "We are looking at different options."

With rail cars expected to arrive in October 2013, Mansourian has stressed the need to get a facility under way soon.

SMART is building an initial 38.8-mile line from Guerneville Road in Santa Rosa to downtown San Rafael, at a cost of $360 million. Plans call for eventually running from Cloverdale to Larkspur.

The Airport Boulevard land is 4.5 miles north of Guerneville Road, the end of the initial segment, and just 3 miles from where a station will some day be located in Windsor.

"It bodes well for Windsor," said SMART Director Debora Fudge, who is Windsor's mayor.

Fudge said that presently there is not enough money to extend the line to Windsor, no time allotted in the train schedule and not enough rail cars on order.

There also has not been any decision on whether SMART would first extend the line northward, or south to Larkspur.

"It is cheaper to extend north to Windsor, but there is high demand to extend to the ferry," Fudge said.

You can reach Staff Writer Bob Norberg at 521-5206 or bob.norberg@<QA0>