Clay dikes protecting the sister cities of Grand Forks, N.D., and East Grand Forks, Minn., turned mushy under heavy rain yesterday and flood fighters routed more residents threatened by the Red River's worst flood this centurey.

The river continued to surge through the area at about 20 feet above flood stage and a foot below the brim of the weakened makeshift levees.

The Neches River crested seven feet above flood stage at Beaumont, Tex., flooding more houses in Jefferson County where 500 families had already abandoned homes will water over the windows.

Barriers built with 50,000 sandbags prevented widespread damage and Beaumont police patrolled the Neches and Hillabrandt Bayou by boat to head off looters.

In Mississippi, the Pearl River was slowly dropping at Columbia, where half the town's 7,500 residents had fled. Civil Defense Director Jim Thornhill said it may be several days before many of the residents, forced out when the river crested 10 feet above flood stage on Saturday, can return home.

Just north of Mobile, at Saraland, about 75 families were evacuated and 200 were put on alert as Bayou Creek overflowed from floodwaters that last week routed 1,000 residents along th eTombigbee, Warrior and Alabama rivers farther upstate.