When the contingent reserve fund for Madison Metro Transit dipped below $125,000 at the end of 2006, staff recommended a series of funding changes to get the account back up to a more comfortable level.
The goal, staff wrote in a set of recommendations for city subcommittees in 2007, was a reserve fund of between $1 million and $3 million.
As Metro Transit navigated the Great Recession, the reserves fluctuated but never got to the low end of that target and even fell below $100,000 after 2010, less than 0.2 percent of that year's total expenditures.
Since then, however, the fund has taken off, surging past the goal to the point where it was projected to exceed $7 million at the end of last year, enough to cover 13 percent of expenditures.
In 2015 alone, a surplus of revenue minus expenditures added more than $2.4 million to the reserve account, according to projected figures in a 10-year financial picture presented to the city's Transit and Parking Commission on Wednesday.
A Metro Transit spokesperson called the size of the contingent reserve unusual, and commission chair Gary Poulson said he hasn't heard concern from other members about it.
"Initially when I heard the figure ... I was a little surprised that it was that high," Poulson said. "I guess I'm not alarmed by it because there's several unknowns in the future here."
Poulson cited the need for a new bus storage facility, for which Metro Transit is applying for a federal grant for a second time. It was denied last year.
Staffing that location and filling in potential city funding gaps in coming years also could draw down the reserves, Poulson said.
But the surplus comes as Metro Transit is preparing to ask for an increase of between 12 percent and 17 percent on some of its fares.
The hike, which would go into effect in September if approved by the Transit and Parking Commission, is planned for some monthly and per-ride plans but not on the $2 base fare or low-income and school-year student cards.
An adult 10-ride card would be $17.50, up from $15. An adult 31-day pass would rise from $58 to $67.50.
A public hearing on the proposed increases is scheduled for 6 p.m. on May 11 at Monona Terrace.
A notice of that hearing said the fare increases will help pay for a short-term bus storage facility; route expansions between the north and east transfer points on weekends and to the Owl Creek neighborhood at midday and evenings; and additional bus cleaners.
Hiking all fares probably would have been a non-starter for the Transit and Parking Commission, Poulson said.
"I don't think we could justify having that kind of contingency and asking across-the-board fare increases," he said. "It just wouldn't fly."
It's unusual for Metro Transit to have such a large reserve balance, said marketing and customer services manager Mick Rusch, who attributed it to recent increases in ridership and passenger revenues. In 2014, Metro Transit exceeded 15 million fixed-route rides for the first time, although boardings were then down 5.7 percent in 2015.
Using more fuel-efficient buses and locking in fuel costs also has helped add to the reserve account, Rusch said.
The balance, he said, has been tapped to pay for a Middleton satellite facility last year and to cover increased insurance costs in 2016. The Middleton location has helped to relieve overcrowding at Metro Transit's East Washington Avenue garage, but a new, east side location has been in the plans.
Metro Transit didn't get awarded a federal grant to help pay for the new facility, however, so plans for construction to start this year were put on hold.
Officials have described the new facility as key in expanding the city's bus fleet.