A Kent council is at risk of running out of emergency cash within four years if it carries on dipping into its reserves at such a rate, financial experts have warned.
Medway Council has spent 44% of the funds since April 2015, with the total falling from around £41 million to £27m at the beginning of last month.
Reserve savings are spent on special projects or emergencies, like flooding.
The authority said it had been forced to spend millions on an influx of appeals against the 2010 business rates at the end of the 2014/15 tax year.
While the vital capital had also been used to fund schemes like the community hub project, which has expanded services at five libraries in the Towns.
Despite Brexit being one challenge pointed to by local government experts as having the potential to drain savings pots, Medway is yet to spend any money preparing for a no-deal scenario.
Chief finance officer Phil Watts said: “Like many other local authorities, Medway Council’s reserves have not been maintained at historic levels due to reduced government funding over the years but we are committed to providing high quality services to Medway’s residents and will continue to do so.
“We are currently in the process of finalising our year end accounts including the final position in terms of council tax and business rates income, however, we would anticipate being able to increase general reserves this year.
“As always we have set a budget for 2019/20 without recourse to general reserves.
"Through the medium term financial planning process we will continue to set sustainable budgets every year.”
The Chartered Institute of Public Finance and Accountancy (Cipfa) have warned 11 local authorities will have fully exhausted their reserves in four years unless they are topped up.
While Cipfa did not name Medway, its spending marks it out as one of those.
Leader of Medway Labour Group Cllr Vince Maple said: "After almost a decade of Tory Austerity councils are facing a funding crisis.
"Medway has seen a 44% reduction in reserves since 2015, even after cutting vital community services such as Sure Start.
"Medway’s financial situation is not helped by the current administration’s poor record on budget priorities.
"It’s simply unacceptable for any council to spend council taxpayer’s money on vanity projects like fireworks displays, Japanese roundabouts, and Dynamic Bus Facilities that are completely unfit for purpose, at the expense of investing in basic services.
"The fact is that councils are unable to run decent services on a shoestring budget.
"It's simply unacceptable for any council to spend council taxpayer's money on vanity projects like fireworks displays, Japanese roundabouts, and Dynamic Bus Facilities that are completely unfit for purpose, at the expense of investing in basic services" - Cllr Vince Maple
"While the government shamelessly enables corporate tax avoidance, residents are expected to fill the funding gap though increasingly regressive council tax, putting more financial pressure on families and working people every year."
Councillor for Luton and Wayfield and Labour audit spokesman Cllr Tristan Osborne added the news is a "flashing red light" and "highlights that we are at huge headwind risk should Brexit result in a downturn in the economy, which will have to lead to increased council tax and parking fees to cover for any future budget black hole."
The Local Government Association said it was unacceptable councils faced the choice of cutting services or plugging gaps with reserve cash.
Medway's rate of spending was matched by Greenwich and Knowsley, with Isles of Scilly, Sutton, Stoke-on-Trent, Croydon, Thurrock, Rotherham and Somerset outspending them.
Northamptonshire County Council, which was forced to stop all but essential spending last year, topped the chart, draining its reservoir by 91%.