The Arlington County board yesterday unanimously adopted a $206.8 million capital improvement program for the next six years, and plans for a new jail brought the current election campaign for county sheriff into the debate.

Ronald B. Hager, who is challenging Sheriff James A. Gondles Jr., said the jail expansion proposal has not been studied adequately. Hager, who spoke during the meeting's public comment period, urged creation of an advisory group to help plan a new facility and asked to be named to it.

"Through sound criminal justice planning, Arlingtonians can be assured future jail projects will meet the needs of our community," he said.

Hager resigned as chief deputy sheriff in March to run as a Republican-backed independent against Gondles, a Democrat, in the Nov. 3 elections. Criticism of the planning for a new jail has been a key part of Hager's campaign.

The capital improvements plan was approved by the board yesterday with the expectation of putting before the voters in November 1988 a $20 million bond referendum for a new jail. The proposal is part of $56.4 million in spending planned for government buildings, including county offices under construction at Court House Plaza.

The jail plans call for building a 396-bed facility on the site of the county-owned Holmes building on Veitch Street across from the courthouse. The current jail was designed to hold 164 inmates but usually has about 197, officials said.

Hager's comments visibly irritated board member Mary Margaret Whipple, a Democrat. When Hager asked for extra time to speak, she responded with a sharp "No." Whipple said two studies of jail needs have been completed already.

Board Vice Chairman John G. Milliken, a Democrat, said jail planners have had to take into account changing national and state standards on the treatment of prisoners.

"Our sheriff has been involved in those issues, and I applaud him for it," said Milliken.

Gondles attended yesterday's board meeting but did not speak publicly. After the session, he defended the jail planning process. "I have done as much as I ought to, and more, to guarantee citizen input," he said.

Other parts of the capital improvements plan caused little controversy. The six-year proposal calls for spending $64.7 million for water and sewers, including upgrading and expanding the waste water treatment plant; $32.4 million for street improvements; $22.8 million for neighborhood conservation programs; $10.3 million for park acquisition, much of it in the Rosslyn-Ballston corridor; $12 million for school buildings; $4.6 million for storm drainage, and $3.6 million for regional programs.