Sediment Reduction Strategy for the Minnesota River Basin and South Metro Mississippi River

High levels of suspended sediment flow through the Minnesota River Basin and subsequently into the Mississippi River. Consequently, many tributaries and river reaches do not meet water quality standards. The Minnesota River contributes approximately 75% of the total suspended solids (TSS) load in the Mississippi River between the Twin Cities and Lake Pepin. At the current sedimentation rate, scientists estimate that Lake Pepin will fill with sediment in approximately 340 years, a rate ten times faster than during pre-European settlement times and nearly four times faster than sediment accumulation rates in 1900. The Minnesota River Basin's geologic history makes the basin vulnerable to high sediment loads, which can increase further when land use changes occur. Near-channel sediment from bluffs, river banks and ravines has been identified as a dominant sediment source in many Minnesota River Basin Watersheds. While these sources are not new, increased river flows have led to near-channel erosion rates that significantly exceed pre-settlement rates. Factors contributing to the increased river flows include changes in precipitation patterns and widespread installation of artificial drainage networks, in addition to other possible contributing factors such as cropping changes. Upland areas, which are dominated by corn and soybean production, also contribute sediment to the river. Implementation of agricultural best management practices (BMPs) on numerous fields have helped reduce soil loss to waters, and further reductions are possible through additional BMPs.