Members of the Prince George's County Council spent most of the day at a retreat to consider the ramifications of a huge casino that will be built here in the next three years.

The first thing the county council members learned: a decision on which of three competing proposals for a P.G.-based casino will come soon. The special state commission hopes to make its choice by December.

A panel of officials and business leaders from Detroit, which already has casino gaming, offered this warning: when a big casino first opens, expect patronage at existing restaurant and entertainment venues to drop off, initially.

Council Chair Andrea Harrison (D) wants to develop a strategy to help support existing businesses. Harrison told us in an interview: "One of the things that was suggested was that inside the casino, vouchers can be offered so that patrons of the casino can go an visit those other businesses outside of the casino facility."

The panel from Detroit also suggested that P.G. officials use their zoning authority to try to extract key concessions from the new casino operator.

The group from Michigan strongly urged the local officials to become solidly united on their priorities, noting that casino operators are huge corporations which are accustomed to dealing with individual cities and counties.

The forthcoming casino in Prince George's County could be huge. One of the proposals submitted to the state would include more than 4,700 electronic gaming machines on the site, plus another 170 table games with human dealers.

Maryland officials hope the new casino in Prince George's County will throw open its doors in July of 2016.