Facing the potential for service failure in the future, King County is considering placing a levy lid lift measure on the spring ballot to fund the estimated $225-million replacement of its regional radio system.

King County Radio Communications project manager David Mendel described the system as nearing a “position of peril” to the Bellevue City Council on Monday. Built using an excess property tax levy approved in 1992, the Puget Sound Emergency Radio Network faces will be at risk of losses in capacity and coverage by 2018, when its service vendor will stop supporting the nearly 20-year-old system, Mendel said. Its replacement will be King County’s most complex and expensive project of this decade, he added.

Rather than going to voters for funding first, Mendel said King County changed its approach with this project and will contract with a vendor for replacement of the system first, in order to know exactly how much funding will be needed.

The $225-million estimate had started at up to $500 million six months ago, before fully analyzing the scope of the project, Mendel said.The levy lid lift measure is likely to appear on April 2015 ballots and, if approved, is estimated to cost county residents between 6.5 to 7 cents per $1,000 of assessed property value over nine years, or about $32 to $35 a year.

The regional radio system is owned by four entities, including the city of Seattle, King County, Valley Communications Center in Kent and the Eastside Public Safety Communications Agency, which holds interlocal agreements with the cities of Bellevue, Redmond, Kirkland, Issaquah and Mercer Island.

Bellevue interim Fire Chief Mark Risen told the council Monday that interlocal agreements on how to fund and manage the system once built are expected to be produced over the next month. Mendel said another interlocal agreement is being developed that would create a new nonprofit to own and operate the system.

Site design work is expected to begin in November and last through June, with 2015-17 slated for site construction, followed by three years of equipment construction. The system is expected to become operational in April 2020.

“We’re actually borrowing from ourselves to do this, right now,” Mendel said, adding those reserve funds being used now are to be replaced through the lid lift.