The State Gaming Commission refines the definition of river channel in determining how land-based a so-called riverboat casino can be. The law allows casinos to be built within one-thousand feet of the closest edge of a river’s main channel. The State Gaming Commission has decided “main channel” can include areas that are normaly dry unless the river is at flood stage. That clears the way for Pinnacle Entertainment to continue with efforts to build a casino in a man-made basin in north St. Louis. A spokesman for a competing company says the river cannot even be seen from the site Pinnacle wants to use. A challenge to the Commission’s ruling is being considered by Columbia Sussex Corporation, which is buying the Presidential Casino out of bankruptcy court. That casino is a few hundred yards downstream from the Pinnacle site.