Suspended-sediment samples have been collected by the U.S. Geological Survey from 115 sites on Minnesota streams since October 1960. Data from 42 sites were sufficient for characterizing sediment concentrations and yields. Average concentrations ranged from 4.4 milligrams per liter on the Baptism River in northeastern Minnesota to 190 milligrams per liter on the Root River in the southeast.
Log-linear equations that describe the sediment-transport curve were developed for 33 daily sediment stations and used to estimate long-term sediment yields. Average annual yields ranged from less than 1.0 ton per square mile on the Pelican River, to more than 200 tons per square mile on the Root and Whitewater Rivers and Deer Creek. Estimates indicated that under extreme circumstances the average annual sediment load for 2 years could be transported in slightly more than one day.
Analysis showed that more than 90 percent of the annual sediment load was carried during 3 to 9 months of the year. On the average, almost 25 percent of the annual sediment load was transported during April. Generally, it was found that less than 4 percent of the average annual load was transported during December, January, and February, which indicates that sampling frequency could be reduced during winter.
