The Anne Arundel County Board of Appeals must apply a more stringent standard to determine whether a Crownsville community will be permitted to build a small marina, the state's highest court ruled yesterday.

Belvoir Farms Homeowners Association received permission in 1997 from the county board to build 18 boat slips, after arguing that denial of its request would prevent members from using the waterfront property. But the Court of Appeals said the association had not proven that a denial would result in undue hardship.

In exchange for approval to build slips at a community pier in Maynadier Creek, the Belvoir Farms group agreed not to use the mooring buoy sites in the creek. But the state's Critical Area Commission opposed 14 of the proposed slips, and took the case to the county Circuit Court.

The Court of Appeals said that Circuit Judge Joseph P. Manck should have sent the case back to the board of appeals and required the homeowners to prove undue hardship.