Board of Education member Rebecca Smondrowski (Rebecca Smondrowski)

The Montgomery County Council tentatively approved $5 billion budget Thursday that increases education funding, expands library hours, fixes more roads and places 10 new police officers on high school campuses.

But the council, which will take final action on the spending plan next week, is also facing criticism for tapping “one-time” sources of cash to pay for ongoing expenses in the new fiscal year that begins July 1.

The fiscal 2015 budget represents a 3.3 percent increase in spending over the current year. But because of rising home assessments, triggered in part by the recovery from the recession, the average annual property tax bill will dip by about $17. The council voted to retain most of the $100 million increase in home and commercial energy taxes levied in 2010 during the economic downturn.

The spending plan keeps the budget proposed in March by County Executive Isiah Leggett (D) largely intact, including the second half of two-year labor contracts he negotiated with police, fire and general non-uniformed county workers. The pacts, with wage and longevity increases averaging 6.75 percent to 9.75 percent, will cost the county about $73 million over the next fiscal year.

Council member Phil Andrews (D-Rockville-Gaithersburg) said he would vote next week against the portion of the budget containing the contract provisions, calling them too costly and unsustainable. Andrews and former county executive Doug Duncan are challenging Leggett in the June 24 Democratic primary.

The new budget is likely to generate controversy because of the council’s decision to fully fund the public school system’s annual request through a series of unusual accounting maneuvers.

To help meet the school system’s request of $51 million over the state-mandated minimum, the county will draw surplus funds from health-care trust accounts for retired and current school system employees. The transaction will not trigger the requirements of the state law providing that any funding over the minimum be counted in next year’s budget “floor.”

The fix has sparked concern among some in the school system that the use of one-time money will create a serious hole in next year’s financial plan.

“By all accounts, this is a faith-based budget with no binding agreement to be fully funded next year,” said Board of Education member Rebecca Smondrowski. “And while it seems like a win right now, the continued greater use of one-time funding sources makes what was already going to be a large fiscal gap for next year even larger. I’m not sure how sustainable this is going to be and with a new council coming in next year ... this commitment just can’t be guaranteed.”

Aides to Leggett also expressed concern Thursday over the council’s decision to use $15 million from a reserve fund set aside in the event that the county loses a major tax case pending before the U.S. Supreme Court.