Byram River, c.20 mi/32 km long, in N.Y. and Conn.; rises in Byram L. S of Mt. Kisco (N.Y.); flows S, through Conn., forming 1.5 mi/2.4 km of S state line, to L.I. Sound at Port Chester, N.Y. Diversion dam directs part of its flow into Kensico Reservoir.