The Arlington County Board works on the upcoming fiscal year's budget on Thursday. (Patricia Sullivan/The Washington Post)

Facing rising costs from Metro and higher school enrollment, the Arlington County Board is poised to pass a 1.5 cent increase in the property tax rate, one-half cent less than what the county manager proposed and the board advertised earlier this year.

The county budget, which the board will vote on Saturday, would grow 4.3 percent over the current year to about $1.2 billion. The tax rate, now 99.1 cents per $100 of assessed value, would climb to just over $1 for the first time since 2013. Combined with higher assessments for most homes, and a rise in a variety of separate fees, the average residential property owner is likely to see a tax increase of about $250.

Board Chairman Jay Fisette (D), who is completing his fifth four-year term this year, said all of the increase would go toward meeting the needs of Metro and the schools, which expect more than 1,000 new students to enroll in the fall.

Arlington Public Schools, Fisette said Thursday during the board’s last workshop session before the Saturday vote, would receive $800,000 more than requested, for a total of $490.3 million, although some of the money would be one-time, rather than ongoing, funds.

County Manager Mark Schwartz said 46.6 percent of all locally generated revenue in the county goes to the school system, not including about $7 million for personnel such as school nurses and crossing guards.

Funding for the Metro system would increase by $7.4 million.

Metro’s general manager on Wednesday called for new, dedicated funds from local governments to provide the troubled transit agency with $500 million a year for equipment and maintenance.

Elected officials in Arlington, which built the modern county around the idea of a transit­dependent lifestyle, supported the idea, but with a big gulp at the potential costs.

“Metro is an impossible lift unless the region comes up with a dedicated funding source,” Fisette said. “If they don’t find that, we’re all in a lot of trouble.”

Board members asked Schwartz last month to tell them which cuts they would have to make to raise the property tax by one cent, instead of two. Board members took his advice for some of those trims — reducing the amount spent on mowing and landscaping, delaying the hiring of some sheriff’s deputies, and reducing his proposed increase in the number of jobs dedicated to improving the county’s street lighting.

But in the end, the board decided to vote on raising the tax rate by 1.5 cents, to allow for additional spending on schools and Metro.

“If you can get the job done with less tax burden, then do it,” Fisette said. “We’re always looking for more efficient ways of accomplishing our goals.”

Board members debated how much money to devote to Columbia Pike improvements, as well as other expenditures, which would be offset by cuts in existing spending.

The board added $100,000 to create a fund for immigration services, which they described as intended to support nonprofit groups responding to “unrest and uncertainty” created by the Trump administration’s renewed focus on deportations.