Flood information is reported for 207 miles of the main stem, 23 miles on the West Branch, and 23 miles on the East Branch, of the Iowa River. The information will be of use to those concerned with the design of bridges and other structures and the conduct of various operations on the flood plains of the streams. Included in the report are flood-peak records, gaging-station records, and water-surface profiles.
Outstanding floods treated in this report are the 1954 flood which is the greatest known in the upper reaches of the Iowa River, the 1969 flood which is the greatest flood in recent years in the central reach of the river, and the 1947 flood which is the greatest flood recorded, excepting the 1918 historic flood, in the lower reaches of the river. Selected data are also given for the 1918 flood, the greatest flood recorded on the Iowa River.
Flood profiles for the main stem include those for the 1947, 1954, 1969, the computed 25- and 50-year floods, and a partial profile for the June 1972 flood. On the West Branch Iowa River, profiles are shown for the 1944, 1969, the computed 25- and 50-year floods, and a partial profile for the June 1954 flood. On the East Branch Iowa River, profiles are shown for the 1954, 1969, the computed 25- and 50-year floods, and a partial profile for the June 1944 flood. Low-water profiles are shown for all reaches.