Missouri River IA 06-WEM-1720

Assessment Comments

Assessment is based on (1) surveys of Nebraska fisheries biologists, (2) consultation with DNR staff and (3) fish tissue (RAFT) monitoring.

Basis for Assessment

Continued to assess support of the Class  B(WW) aquatic life uses as PS due to habitat alterations and  flow modifications that resulted from development of the river for navigation uses in the mid-Twentieth Century.   This assessment was presented to the Nebraska fisheries biologist for the Missouri River  and to DNR/EPD staff with historical involvement with Missouri River issues.   These professionals agreed with the assessment that aquatic life uses are "partially supported."  The habitat alterations are due to channelization of the river, while the flow modifications are due primarily to control of river flows  through the system of mainstem dams upriver from Sioux City.   Continued to assess support of the fish consumption uses as FS  based on results of 1991 RAFT monitoring near Sergeant Bluff that showed that levels of all contaminants were less than 1/2  of the respective FDA action levels in the composite samples of channel catfish fillets.   Waterbody included on Iowa's 1998 Section 303(d) list due to alterations of flow and habitat.