Cities in King County should continue planning new jails in order to meet eventual demands for more jail space, according to a county report.

The report, part of a regional effort begun in 2006 to prepare for future jail needs, is tied to the county’s joint planning with cities whose contracts to use the county jail are scheduled to expire in 2012, officials said.

County Executive Ron Sims said the region’s collective jail space needs can’t be met within existing county facilities, even with a planned expansion of the Norm Maleng Regional Justice Center in Kent. He has called for accelerated discussions of alternatives, including moving forward with planning for an expansion of the Kent facilities.

King County is required by law to house individuals charged with felonies prior to trial, charged with or convicted of misdemeanors originating in unincorporated King County, and convicted of felonies and sentenced to serve less than one year. County officials predict that by 2024, space for roughly 300 more inmates than is currently available will be needed.

The 36 contract cities (all cities countywide except for Kent, Enumclaw and Milton), which are responsible for the detention of individuals charged with or sentenced for misdemeanor offenses originating within a city’s jurisdiction, project a total inmate population of 1,450 by 2026. This amount exceeds the total existing jail bed capacity at the contract cities’ existing municipal jails by over 1,200 inmates, according to county officials. When the current contract ends in 2012, there won’t be enough jail space for city and county inmates, and by 2026, city and county inmate populations will far exceed any regional jail capacity, officials said.