 Hydrologically , the portion of the river upstream of the proposed dam drains about 200 @,@ 000 square miles ( 517 @,@ 998 km2 ) . On average , the Yukon flows at a rate of 118 @,@ 000 cubic feet per second ( 3 @,@ 341 m3 / s ) through the canyon , with the fastest flow occurring in the later part of May and the first part of June , and the slowest flow occurring after the river has frozen over . This occurs no later than early November and lasts until mid April . 
