After two years of public meetings, studies and impassioned arguments, the fate of the former Air Force radar tower on the summit of Mount Umunhum south of San Jose is set to be decided Wednesday evening.

And in what appears to be a last-minute attempt at compromise, the board of the Midpeninsula Regional Open Space District, a government agency that owns the 80-foot-high concrete structure, will weigh two options to leave the tower standing for five years while money can be raised to save it from demolition.

"At one time, we were saying the thing has pretty much got to go down," said Curt Riffle, chairman of the open space district's board. "We're an open space district. But now because of the public input we need to think about it in more of a regional context."

Veterans have come out in favor of keeping the radar tower, which once scanned the skies for Soviet bombers during the Cold War -- but today is known mostly for its distinct cube shape, visible to people across Silicon Valley who look south to the Santa Cruz Mountains.

"Like a lot of residents of the valley, we've grown accustomed to that tower," said Bob Watts of Morgan Hill, who served as a radar operator there from 1960 to 1962. "It brings back memories. It was a vital part to the West Coast defense of the United States."

At its peak, 120 Air Force personnel and their families lived at the Almaden Air Force Station , which had homes, a gymnasium, garages and even a bowling alley. The base operated from 1957 to 1980, when it was made obsolete by satellites. It was acquired in 1986 by the open space district, based in Los Altos.

Since then, the district has purchased 18,000 acres around the summit to create an area named the Sierra Azul Open Space Preserve, with trails for hiking, biking and horse riding. Still, the summit has remained behind locked gates. Over the past two years, with funds from Congress, the district removed lead paint, PCBs and other contaminants from 80 failing buildings. Demolition of those buildings is expected to begin next month and be completed by next summer.

The district hopes to eventually allow people to drive to the top of the 3,486-foot peak, after it comes up with $4 million to fix the road to the top. The summit of the mountain, which is named for the Ohlone Indian word for "resting place of the hummingbird," has breathtaking views of San Francisco Bay and Monterey Bay.

Originally, the district was considering three options for the radar tower. The first was tearing it down, at a cost of about $640,000. The second was tearing down all but a 10-foot-high foundation and making a public plaza, at a cost of about $817,000. The third was sealing and retrofitting it, for $1.1 million, with about $750,000 in maintenance costs over 40 years.

But last month, the Santa Clara County Historical Heritage Commission supported keeping the tower, which could make it problematic for the open space agency to obtain a county demolition permit. More troublesome, the open space district in 2014 is expected to go to voters seeking new tax funding. That measure will need a two-thirds majority to pass, and a clash with veterans groups could make that difficult.

On Friday, when the staff report for Wednesday's meeting came out, there were two new options: making some repairs and leaving it up for five years, at a cost of $414,000, or fencing it off at a cost of $74,500. In both cases, the agency would look for donors to help fund restoration costs.

Former Oakland A's owner Steve Schott has pledged $200,000. The exact total that would need to be raised will be among the subjects discussed at the board meeting.

"It's good that they are thinking of easing up and adding these interim actions that involve keeping the tower," said Basim Jaber, a San Jose historian who has gathered 2,200 signatures to do just that. "It means they have been listening to the public outcry and input. But it doesn't clearly define what their involvement is.

"It has to be a true partnership. They have to help raise money and want this to succeed."

Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN

IF YOU'RE INTERESTED
The Midpeninsula Regional Open Space District will consider the fate of Mount Umunhum's radar tower at 7 p.m. at the Historic Del Monte Building at 100 S. Murphy Avenue, Sunnyvale.
For more information, go to www.openspace.org